CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/837,356, filed June 20, 2013 and U.S. Provisional Patent Application No. 61/894,666, filed October 23, 2013, the contents of which are hereby incorporated by reference in its entirety.

BRIEF SUMMARY OF THE INVENTION

[0002] This disclosure relates generally to processes for removing silicone resins from a substrate. More specifically, this disclosure relates to methods for removing cured resin coatings from a resin-coated substrate by soaking a resin-coated substrate in (i) concentrated sulfuric acid or (ii) a mixture of concentrated sulfuric acid mixed with one or more organic compounds wherein the total sulfuric acid concentration of the mixture is at least 20 weight percent, where the resin of the cured resin coating is an Si-O-Si containing silicone resin; washing away the degraded resin coating from the resin-coated substrate with select organic solvent(s) and washing the resulting substrate with water to remove the organic solvent(s) and/or contaminants and form a cleaned substrate substantially lacking the cured resin coating (or a reaction product thereof) and substantially lacking the degraded resin coating (or a reaction product thereof). The amount of any residue remaining on the cleaned substrate is from 0 to less than 0.20 weight percent in embodiments of the method where the resin-coated substrate is soaked in the (i) concentrated sulfuric acid and from 0 to less than 0.26 weight percent in embodiments of the method where the resin-coated substrate is soaked in the (ii) a mixture of concentrated sulfuric acid mixed with one or more organic compounds. The methods disclosed herein provide high throughput and speed of removal of the cured resin coating from the substrate using chemicals that do not damage the substrate.

DETAILED DESCRIPTION OF THE INVENTION

[0003] Silicone resin materials have been widely used in the microelectronics packaging industry due to their excellent thermal stability, hydrophobicity, good adhesion, and excellent elastic properties. In many instances, it is highly desired that the cured silicone coating or layer on the substrate be removed for reclaiming of the substrate, e.g., if the cured silicone layer is used as a sacrificial layer or material, or for reworkability of a device substrate. Methods which can readily facilitate removal of a cured silicone resin from a substrate for substrate reclaim or from a device substrate are desired. Theoretically, silicone resin can be degraded under acid and basic conditions. However, removal of silicone resin is very challenging. Some silicone removal chemicals are commercially available, such as DIGESIL® NC Xtra (available from RPM Technology, LLC, Reno, NV) and DYNASOLVE (available from Dynaloy, LLC, Indianapolis, Indiana) materials. With these chemicals, however, the stripping time is unacceptably long, particularly for industries such as the microelectronics packaging industry which requires very short silicone removal times (e.g., less than two hours) and high throughput. A prolonged silicone removal process is not viable for the mass production required in the microelectronics industry. Additionally, some silicones cannot be completely removed with these commercial chemicals; consequently, these commercial chemicals are unsuitable for producing microelectronics devices with strict limits on surface residue contamination. Therefore, it is highly desirable to develop a method to remove silicone resins from substrates in very short periods of time (e.g., less than two hours) to meet the microelectronics industry requirements for high throughput, low cost of ownership, and high surface clean quality.

[0004] According to the inventive methods, a cured resin material is removed from a resin- coated substrate formed of a substrate having the cured resin coating thereon by a method comprising soaking the resin-coated substrate in a concentrated sulfuric acid-based reagent (that is, the (i) an aqueous, concentrated sulfuric acid or the (ii) a mixture (e.g., solution) of concentrated sulfuric acid mixed with one or more organic compounds, wherein in some embodiments the mixture may be a solution), where the resin is a cured Si-O-Si containing silicone resin. In other embodiments, the mixture (ii) may alternatively be a suspension or alternatively be a colloid. The resin of the cured resin coating is used to form the resin- coated substrate.

[0005] According to the inventive methods, the sulfuric acid of the aqueous, concentrated sulfuric acid is at a concentration that is effective for producing a degraded resin coating and, ultimately, completely removing any resin residue from the resin-coated substrate or removing resin residue from the resin-coated substrate such that any silicone residue remaining on the substrate is from 0 to less than 0.20 weight percent (wt.%). In some embodiments, the sulfuric acid of the (i) aqueous, concentrated sulfuric acid is at a concentration of at least 95 wt.% and, in some embodiments, at a concentration of at least 96 wt.%. The concentration level of the sulfuric acid of the (i) aqueous, concentrated sulfuric acid is determined by dilution of commercially available concentrated sulfuric acid with the appropriate amount of water to reach the desired sulfuric acid concentration level (for example, dilution of 99.999 wt.% commercially available concentrated sulfuric acid to reach a desired 95% wt.% concentration). The aqueous, concentrated sulfuric acid levels detailed herein may be prepared by any suitable method such as methods known for preparing same and, alternatively, may be purchased from a commercial supplier thereof such as Sigma- Aldrich Chemical Company (St. Louis, MO) (product no. 339741 ) and used as supplied or by diluting to the sulfuric acid concentration level.

[0006] In some embodiments, the concentration of sulfuric acid of the (i) aqueous, concentrated sulfuric acid may be 96 wt.%, 97 wt.%, 98 wt.%, 99 wt.%, or 99.9 wt.%. In still further embodiments, the concentration of sulfuric acid of the (i) aqueous, concentrated sulfuric acid may alternatively be 96 wt.%, 97 wt.%, 98 wt.%, 99 wt.%, or 99.9 wt.% except wherein any one of the concentrations 96 wt.%, 97 wt.%, 98 wt.%, 99 wt.%, and 99.9 wt.% is excluded therefrom.

[0007] In yet further embodiments, the sulfuric acid of the (i) aqueous, concentrated sulfuric acid is at a concentration of 95 to < 100 wt.%; alternatively, at a concentration of 96 to < 100 wt.%; alternatively, at a concentration of 97 to < 100 wt.%; alternatively, at a concentration of 97 to < 100 wt.%; alternatively, at a concentration of 98 to < 100 wt.%; and alternatively, at a concentration of 99 to < 100 wt.%.

[0008] In yet further embodiments, the sulfuric acid of the (i) aqueous, concentrated sulfuric acid is at a concentration of at least 95.5 wt.%; alternatively, at least 96.5 wt.% in other embodiments; alternatively, at least 97.5 wt.% in further embodiments; alternatively, at least 98.5 wt.% in still further embodiments; and alternatively, at least 99.5 wt.% in yet further embodiments.

[0009] In some embodiments, the sulfuric acid of the (i) aqueous, concentrated sulfuric acid may be at most 99.999 wt.%. In yet other embodiments, the sulfuric acid of the concentrated sulfuric acid may be 100 wt.%.

[0010] It is also alternatively contemplated that the (ii) a mixture of concentrated sulfuric acid mixed with one or more organic compounds may be used. The mixture may be a solution, a suspension, or a colloid. In other words, the mixture (ii) may be just a solution, alternatively just a suspension, or alternatively just a colloid. Where the (ii) a mixture of concentrated sulfuric acid mixed with one or more organic compounds (also referred to herein as "the sulfuric acid-organic compound mixture," wherein the hyphen does not represent a covalent bond) is used, the sulfuric acid-organic compound mixture includes (1 ) concentrated sulfuric acid having a starting concentration (i.e., the concentration prior to mixing the concentrated sulfuric acid ingredient with the one or more organic compounds to form the sulfuric acid- organic compound mixture) of at least 95 wt.% and, in some embodiments, at a concentration of at least 96 wt.%, (2) an alkane solvent having 5 or more carbons and combination(s) thereof, and (3) optionally, an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, or any combination(s) thereof (i.e., a combination of any two or more of an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, and a carboxylic acid salt). The total concentration of the sulfuric acid in the sulfuric acid-organic compound mixture is at least 20 wt.% and, in some embodiments, the total concentration of the sulfuric acid is at least 30 wt.%. In some embodiments, the total concentration of the sulfuric acid in the sulfuric acid- organic compound mixture is at least 20 wt.% to 80 wt.%. The total concentration of the sulfuric acid in the sulfuric acid-organic compound mixture is calculated by measuring the weight of concentrated sulfuric acid divided by the total weight of the mixture, expressed as a percent. According to the inventive methods, where a sulfuric acid-organic compound mixture is used, the sulfuric acid of the sulfuric acid-organic compound mixture is at a concentration that is effective for producing a degraded resin coating and, ultimately, completely removing any resin residue from the resin-coated substrate or removing resin residue from the resin-coated substrate such that any silicone residue remaining on the substrate is less than 0.26 wt.% (that is, from 0 to less than 0.26 wt.%).

[0011] In some embodiments, the starting concentration of sulfuric acid used to prepare the (ii) sulfuric acid-organic compound mixture may be 96 wt.%, 97 wt.%, 98 wt.%, 99 wt.%, or 99.9 wt.%. In still further embodiments, the starting concentration of sulfuric acid used to prepare the (ii) sulfuric acid-organic compound mixture may alternatively be 96 wt.%, 97 wt.%, 98 wt.%, 99 wt.%, or 99.9 wt.% except wherein any one of the starting concentrations 96 wt.%, 97 wt.%, 98 wt.%, 99 wt.%, and 99.9 wt.% is excluded therefrom.

[0012] In yet further embodiments, the sulfuric acid used to prepare the (ii) sulfuric acid- organic compound mixture is at a starting concentration of 95 to < 100 wt.%; alternatively, at a starting concentration of 96 to < 100 wt.%; alternatively, at a starting concentration of 97 to < 100 wt.%; alternatively, at a starting concentration of 97 to < 100 wt.%; alternatively, at a starting concentration of 98 to < 100 wt.%; and alternatively, at a starting concentration of 99 to < 100 wt.%.

[0013] In yet further embodiments, the sulfuric acid used to prepare the (ii) sulfuric acid- organic compound mixture is at a starting concentration of at least 95.5 wt.%; alternatively, at least 96.5 wt.% in other embodiments; alternatively, at least 97.5 wt.% in further embodiments; alternatively, at least 98.5 wt.% in still further embodiments; and alternatively, at least 99.5 wt.% in yet further embodiments.

[0014] In some embodiments, the sulfuric acid used to prepare the (ii) sulfuric acid-organic compound mixture may be at a starting concentration of at most 99.999 wt.%. In yet other embodiments, the sulfuric acid of the (ii) sulfuric acid-organic compound mixture may be at a starting concentration of 100 wt.%.

[0015] In some embodiments, the total concentration of sulfuric acid used to prepare the (ii) sulfuric acid-organic compound mixture may be at least 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.% or 30 wt.%. In further embodiments, the total concentration of sulfuric acid of the (ii) sulfuric acid-organic compound mixture may be at least 31 wt.%, 32 wt.%, 33 wt.%, 34 wt.%, 35 wt.%, 36 wt.%, 37 wt.%, 38 wt.%, 39 wt.% or 40 wt.%. In still further embodiments, the total concentration of sulfuric acid in the (ii) sulfuric acid-organic compound mixture may alternatively be 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.% or 30 wt.% except wherein any one of the starting concentrations 20 wt.%, 21 wt.%, 22 wt.%, 23 wt.%, 24 wt.%, 25 wt.%, 26 wt.%, 27 wt.%, 28 wt.%, 29 wt.% or 30 wt.% is excluded therefrom. In still further embodiments, the total concentration of sulfuric acid in the (ii) sulfuric acid-organic compound mixture may alternatively be 31 wt.%, 32 wt.%, 33 wt.%, 34 wt.%, 35 wt.%, 36 wt.%, 37 wt.%, 38 wt.%, 39 wt.% or 40 wt.% except wherein any one of the starting concentrations 31 wt.%, 32 wt.%, 33 wt.%, 34 wt.%, 35 wt.%, 36 wt.%, 37 wt.%, 38 wt.%, 39 wt.% or 40 wt.% is excluded therefrom.

[0016] In yet further embodiments, the sulfuric acid of the (ii) sulfuric acid-organic compound mixture is at a total concentration of at least 20.5 wt.%; alternatively, at least 21.5 wt.% in other embodiments; alternatively, at least 22.5 wt.% in further embodiments; alternatively, at least 23.5 wt.% in still further embodiments; alternatively, at least 24.5 wt.% in yet further embodiments; alternatively, at least 25.5 wt.% in yet further embodiments; alternatively, at least 26.5 wt.% in still further embodiments; alternatively, at least 27.5 wt.% in yet further embodiments; alternatively, at least 28.5 wt.% in still further embodiments; and alternatively, at least 29.5 wt.% in yet further embodiments. It is also contemplated that the sulfuric acid of the (ii) sulfuric acid-organic compound mixture is at a total concentration of at least 30.5 wt.%; alternatively, at least 31.5 wt.% in other embodiments; alternatively, at least 32.5 wt.% in further embodiments; alternatively, at least 33.5 wt.% in still further embodiments; alternatively, at least 34.5 wt.% in yet further embodiments; alternatively, at least 35.5 wt.% in still further embodiments; alternatively, at least 36.5 wt.% in yet further embodiments; alternatively, at least 37.5 wt.% in still further embodiments; alternatively, at least 38.5 wt.% in yet further embodiments; and alternatively, at least 39.5 wt.% in still further embodiments.

[0017] Suitable safety and environmental protection precautions for handling, using and disposing concentrated sulfuric acid should be taken when performing the methods described herein.

[0018] According to the inventive methods, the degraded resin coating resulting from the soaking step is washed away with a first organic solvent or mixtures thereof. The washed substrate may optionally be further washed with a second organic solvent or mixtures thereof following the washing with the first organic solvent or mixtures thereof. The substrate resulting from the organic solvent washing step(s) is then washed with water to remove the first organic solvent(s) (and, if used, the second organic solvent(s)) and form a cleaned substrate substantially lacking the cured resin coating (or a reaction product thereof) and substantially lacking the degraded resin coating (or a reaction product thereof). Contaminants present on the substrate will also be removed from the organic solvent(s) washing and water washing steps. The substrate substantially lacking the cured resin coating and substantially lacking the degraded resin coating may be dried with air, argon, nitrogen or mixtures thereof. Upon drying, the substrate may also lack the organic solvent(s).

[0019] The resin-coated substrate is formed by coating a curable Si-O-Si containing silicone resin onto the substrate to a resin coating thickness of from greater than 0 millimeter up to about 1 millimeter (mm) to form a curable resin-coated substrate. The curable Si-O-Si containing silicone resin of the coating is cured to yield a cured form of the resin-coated substrate. The curable resin including the curable Si-O-Si containing silicone resin used for coating the substrate to form the curable resin-coated substrate may be partially cured prior to application onto the substrate and/or cured after or upon application onto the substrate. The curable Si-O-Si containing silicone resin is cured prior to soaking the resin-coated substrate in the concentrated sulfuric acid-based reagent. The curable resin used for coating the substrate to form the curable resin-coated substrate may be partially cured prior to application onto the substrate and/or cured after or upon application onto the substrate.

[0020] Coating the Resin on the Substrate

[0021] According to the inventive methods, a resin is coated onto a substrate to a resin thickness of from greater than 0 mm up to about 1 mm. The resin is a curable resin. In some embodiments, the resin is coated onto the substrate to a resin thickness of from greater than 0 mm up to about 500 microns. In further embodiments, the resin is coated onto the substrate to a resin thickness from about 2 microns to about 500 microns. In still further embodiments, the resin is coated onto the substrate from about 5 microns to about 200 microns.

[0022] The resin used for coating the substrate to form the resin-coated substrate is a curable Si-O-Si containing silicone resin. In some embodiments, the resin may be a polymer comprising macromolecules with Si-O-Si in the main chain (i.e., the Si-O-Si is in or part of the backbone). In other words, the resin of the cured resin coating is a polymer comprising macromolecules with Si-O-Si, where the Si-O-Si is part of backbones of the macromolecules.

[0023] In still further embodiments, the curable resin may contain the following structural unit:

R R

Si— O— Si

R R wherein each R is independently an organic group selected from alkyl and aryl substituents such as, but not limited to, methyl, ethyl, phenyl, and trifluoropropyl groups. The resin may be a curable polydimethylsiloxane-based resin. The polydimethylsiloxane-based resin may comprise a vinyl-functionalized polydimethylsiloxane polymer, an Si-H functional polydimethylsiloxane crosslinker, an alkenyl functional filler, and a metal catalyst. The metal catalyst is effective for enhancing a reaction between the vinyl-functionalized polydimethylsiloxane polymer and an Si-H functional polydimethylsiloxane crosslinker and between the Si-H functional polydimethylsiloxane crosslinker and the alkenyl functional filler. The reaction may be a hydrosilylation reaction, and the metal catalyst may be a hydrosilylation reaction catalyst such as a Pt-based hydrosilylation reaction catalyst. The curable resin used for coating the substrate to form the curable resin-coated substrate may be partially cured prior to application onto the substrate and/or cured after or upon application onto the substrate.

[0024] The substrate used in the inventive methods can be a silicon wafer, a silicon plate, a glass wafer, a glass plate, a silicon carbide wafer, a silicon carbide plate, a patterned silicon wafer, a patterned glass wafer, a patterned silicon carbide wafer, a device wafer, a device plate, or any other suitable substrate. The term "silicon wafer" (also referred to as a slice or substrate) refers to a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices; the "silicon wafer" serves as the substrate for microelectronic devices built in and over the wafer and undergoes a number of microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. The term "silicon plate" refers to a thin slice of semiconductor material with shapes, e.g., rectangle, square and other shapes other than a circle, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices; the "silicon plate" serves as the substrate for microelectronic devices built in and over the plate and undergoes a number of microfabrication process steps such as doping or ion implantation, etching, deposition of various materials, and photolithographic patterning. The substrate can be a bare substrate (a substrate without any coating thereon or any treatment on its surface) or a substrate coated with one or more protective coatings. Furthermore, the substrate can be a patterned device substrate. Nonlimiting examples of suitable substrates include bare silicon wafers, bare glass wafers, patterned silicon wafers, patterned glass wafers and patterned silicon carbide wafers.

[0025] The surface of the substrate which is directly in contact with the concentrated sulfuric acid should be highly non-reactive with the concentrated sulfuric acid (or, if used, the sulfuric acid-organic compound mixture) within a time frame of about 10 to about 60 minutes. The substrate may be coated with a protective layer that is highly non-reactive with the concentrated sulfuric acid (or, if used, the sulfuric acid-organic compound mixture). By the phrase "highly non-reactive with the concentrated sulfuric acid" or "highly non-reactive with the sulfuric acid-organic compound mixture," it is intended that the surface of the substrate or the protective layer/coating on the substrate (where one is employed) will not be damaged by the sulfuric acid within 1 or 2 hours (e.g., < 120 minutes, alternatively < 90 minutes, and alternatively < 60 minutes) during the silicone stripping process. The protective layer is coated onto a patterned wafer of silicon, glass or silicon carbide or a patterned plate of silicon, glass or silicon carbide prior to coating the silicone resin. This protects the pattern of the patterned wafer or plate from corrosion and/or deterioration caused by the concentrated sulfuric acid. In some embodiments, the protective layer is in direct physical contact with the substrate. In alternative embodiments, the protective layer is in direct physical contact with the cured resin coating of the Si-O-Si containing silicone resin. In still further embodiments, the protective layer is in direct physical contact with both the substrate and the Si-O-Si containing silicone resin. In some embodiments, the protective layer is disposed between the substrate and the Si-O-Si containing silicone resin of the cured resin coating. The protective layer can be made from a variety of materials such as, but not limited to, polyimide, silicon nitride, etc.

[0026] Curing of the Resin-Coated Substrate

[0027] Upon formation of the resin-coated substrate, the coated resin on the substrate is cured. The curing may be, for example, a thermal cure or a photochemical cure. The curing mechanism may include condensation cure or addition cure. By way of example, condensation curing may be catalyzed by a variety of things such as titanium or tin compounds. Also by way of example, addition curing may include hydrosilylation cure, often with a platinum- or rhodium-based catalyst, or free radical cure, often with a free radical initiator/photo radical initiator, or a thermal acid generator/photo acid generator. Any suitable curing technique which results in suitable crosslinking may be employed. The curing occurs prior to soaking the resin-coated substrate in the concentrated sulfuric acid-based reagent.

[0028] Soaking of the Resin-Coated Substrate

[0029] According to the inventive methods, the resin-coated substrate is soaked in a concentrated sulfuric acid-based reagent (that is, the (i) an aqueous, concentrated sulfuric acid or the (ii) a mixture (e.g., solution) of concentrated sulfuric acid mixed with one or more organic compounds as detailed below).

[0030] Soaking in (i) Aqueous, Concentrated Sulfuric Acid

[0031] According to the inventive methods, where the aqueous, concentrated sulfuric acid (i) is used, the aqueous, concentrated sulfuric acid is at a concentration of at least 95 weight percent (wt.%). In some embodiments, where the aqueous, concentrated sulfuric acid is used, the aqueous, concentrated sulfuric acid is at a concentration of at least 96 wt.%. In further embodiments, where the aqueous, concentrated sulfuric acid is used, the aqueous, concentrated sulfuric acid is at a concentration of at least 97 wt.%. In still further embodiments, where the aqueous, concentrated sulfuric acid is used, the aqueous, concentrated sulfuric acid is at a concentration of at least 98 wt.%. In yet further embodiments, where the aqueous, concentrated sulfuric acid is used, the aqueous, concentrated sulfuric acid is at a concentration of at least 99 wt.%. In still further embodiments, where the aqueous, concentrated sulfuric acid is used, the aqueous, concentrated sulfuric acid is at a concentration of at least 100 wt.%.

[0032] Soaking in the (ii) Mixture (e.g., Solution) of Concentrated Sulfuric Acid Mixed with One or More Organic Compounds

[0033] Where the mixture (e.g., solution) of concentrated sulfuric acid mixed with one or more organic compounds (ii) (also referred to herein as "the sulfuric acid-organic compound mixture") is used, the sulfuric acid-organic compound mixture includes (1 ) concentrated sulfuric acid having a starting concentration of at least 95 wt.%, (2) an alkane solvent having 5 or more carbons and combination(s) thereof, and (3) optionally, an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, or any combination thereof. In further embodiments, the concentrated sulfuric acid in the sulfuric acid-organic compound mixture is at a starting concentration of at least 96 wt.%. In yet further embodiments, the concentrated sulfuric acid in the sulfuric acid-organic compound mixture is at a starting concentration of at least 97 wt.%. In still further embodiments, the concentrated sulfuric acid in the sulfuric acid-organic compound mixture is at a starting concentration of at least 98 wt.%. In yet further embodiments, the concentrated sulfuric acid in the sulfuric acid-organic compound mixture is at a starting concentration of at least 99 wt.%. In some embodiments, the concentrated sulfuric acid in the sulfuric acid-organic compound mixture is at a starting concentration of at most < 100 wt.%, alternatively < 99.99 wt.%, alternatively < 99.9 wt.%.

[0034] Where the sulfuric acid-organic compound mixture is used, the total concentration of the sulfuric acid in the mixture (e.g., solution) is at least 20 wt.%. In yet further embodiments, the total concentration of the sulfuric acid in the mixture (e.g., solution) is at least 30 wt.%. In still further embodiments, the total concentration of the sulfuric acid in the mixture (e.g., solution) is at least 40 wt.%. In yet further embodiments, the total concentration of the sulfuric acid in the mixture (e.g., solution) is at least 50 wt.%. In some embodiments, the total concentration of the sulfuric acid in the mixture (e.g., solution) is at most 90 wt.%, alternatively, at most 80 wt.%, alternatively at most < 70 wt.%. In some embodiments, the total concentration of the sulfuric acid in the mixture (e.g., solution) is at least 20 wt.% to 80 wt.%.

[0035] As detailed above, the sulfuric acid-organic compound mixture includes (2) an alkane solvent having 5 or more carbons. Examples of alkane solvents having 5 or more carbons include, but are not limited to, heptanes, octanes, nonanes, decanes, undecanes, dodecanes, tetradecanes, and cyclic alkanes (such as cyclohexane). The sulfuric acid- organic compound mixture may include more than one alkane solvent(s) having 5 or more carbons. Each alkane solvent independently may have 30 carbons or fewer, alternatively 25 carbons or fewer, alternatively 20 carbons or fewer, alternatively 15 carbons or fewer. The number of carbon atoms in the alkane solvent(s) is on average per molecule. Alternatively or additionally, the alkane solvent(s) may be described by its boiling point or, for mixtures of alkane solvents, boiling point range. In some embodiments, the alkane solvent(s) may have a boiling point of at least 36 degrees Celsius (°C), alternatively at least 100°C, alternatively at least 150°C. Alternatively or additionally, the alkane solvent(s) may have a boiling point of at most 400°C, alternatively at most 350°C, alternatively at most 300°C, alternatively at most 250°C.

[0036] As detailed above, the sulfuric acid-organic compound mixture optionally includes (3) an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, or any combination(s) thereof. Examples of aromatic sulfonic acids include, but are not limited to, dodecyl benzenesulfonic acid, benzenesulfonic acid, toluene sulfonic acid, decyl benzyl sulfonic acid, 4-dodecyl benzyl sulfonic acid (DBSA), and salts thereof. Examples of aliphatic sulfonic acids include, but are not limited to, methane sulfonic acid, ethane sulfonic acid, butane sulfonic acid, decane sulfonic acid, dodecanesulfonic acid, and salts thereof. Examples of carboxylic acids include, but are not limited to, formic acid, acetic acid, propionic acid, butanoic acid, and salts thereof.

[0037] In still further embodiments, where the sulfuric acid-organic compound mixture is used, commercially available materials containing an alkane solvent(s) having 5 or more carbons and, optionally, aromatic sulfonic acid(s), aliphatic sulfonic acid(s), and/or carboxylic acid(s) and/or salts thereof may be used. Two such suitable commercially available materials include DIGESIL® NC Xtra and DYNASOLVE. DIGESIL® NC Xtra contains mid petroleum distillates and dodecylbenzene sulfonic acid. Petroleum distillates other than DIGESIL® NC Xtra may be used, particularly middle petroleum distillates (for example, fuel oils, gas oils) containing paraffins with a distillation range of between 150°C and 450°C (using ASTM D 86-67 titled "Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure"). In some embodiments, the petroleum distillates contemplated for use herein have a distillation range from an initial boiling point of between 160°C and 190°C to a cut point of between 350°C and 390°C. DYNASOLVE contains synthetic isoparaffinic hydrocarbon or hydrogenated petroleum naphtha and dodecylbenzene sulfonic acid. Petroleum naphtha is an intermediate hydrocarbon liquid stream derived from the refining of crude oil. Examples of commercially available DYNASOLVE products suitable for the sulfuric acid-organic compound mixture include, but are not limited to, DYNASOLVE 218, DYNASOLVE 220, DYNASOLVE 225, and DYNASOLVE 230. [0038] The soaking of the resin-coated substrate in the concentrated sulfuric acid-based reagent (that is, (i) the aqueous, concentrated sulfuric acid or (ii) the sulfuric acid-organic compound mixture) is for from greater than 0 to about 60 minutes. By soaking the resin- coated substrate in the concentrated sulfuric acid-based reagent, a significant amount of the cured resin coating is degraded from the substrate within approximately 10 to 20 minutes. Using the inventive methods, silicone resins are removed from the substrates described herein in a manner suitable for the microelectronics industry at high throughput levels, low cost of ownership levels, and with high surface clean quality in less than two hours. The desired length of the soaking time depends on the thickness of the resin and the crosslink density of the resin. If the film thickness is low, very short soaking time is needed to remove the resin from the resin-coated substrate. The soaking process may be carried out at room temperature or a higher temperature as needed. For example, the soaking process may be carried out at a temperature ranging from about 23°C to about 150°C. Higher temperature may accelerate the silicone resin removal rate.

[0039] During the soaking process, heating, mechanical stirring, ultrasound, magsound or other suitable techniques to aid in degradation or removal of the cured resin coating from the substrate may be employed to expedite the resin removal process.

[0040] After the substrate is soaked in the concentrated sulfuric acid-based reagent, residual resin or residue may remain attached to the substrate. To remove any remaining resin from the substrate, the substrate is washed as detailed below.

[0041] Washing Away the Degraded Resin Coating with Organic Solvent(s)

[0042] Due to the high dynamic viscosity of the silicone resin (1 ,000-1 ,000,000 centiPoise (cP) at 20°C) and the concentrated sulfuric acid (26.7 cP at 20°C) as well as the limited solubility of the degraded resin in the concentrated sulfuric acid, the degraded resin resulting from the soaking step is washed with a first organic solvent or mixtures thereof. The washing process can be simple flushing, soaking into the first organic solvent(s), or any suitable technique for washing or rinsing away the degraded resin coating from the substrate. The first organic solvent(s) are carbon-based, water miscible liquids that are effective for washing the high dynamic viscosity, limited solubility silicone-based materials. The first organic solvent(s) are polar, organic solvents suitable for removing the degraded resin coating from the substrate selected from isopropyl alcohol (I PA), acetone, 2-butanone, 1-propanol, 2-propanol, 1 -butanol, 2-butanol, dimethyl sulfoxide (DMSO), propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether, or mixtures thereof. In some embodiments, the first organic solvent is isopropyl alcohol, acetone or a mixture of isopropyl alcohol and acetone. The solvent(s) selected for the first organic solvent(s) should be highly non-reactive with the concentrated sulfuric acid and should not interact with the damaged/decomposed resin. [0043] Following the washing with the first organic solvent(s), an optional second washing with a second organic solvent or mixtures thereof may be employed to further wash or rinse away the degraded resin coating from the substrate. Here, too, the washing process can be simple flushing, soaking into the second organic solvent, or any suitable technique for washing or rinsing away the degraded resin coating from the substrate. The second organic solvent(s) is any carbon-based liquid that is effective for washing the first organic solvent. The second organic solvent(s) is an organic solvent selected from alkanes, aromatic hydrocarbons, carboxylic esters, alcohols, ketones, ethers, or mixture(s) of these solvents suitable for removing the degraded coating from the substrate. Suitable representative examples of the optional second organic solvent include I PA, n-butanol, 1 -butanol, 2- butanol, acetone, acetonitrile, 2-methoxy ethanol, 2-ethoxy ethanol, propylene glycol monomethyl ether, propylene glycol methyl ether acetate (PGMEA), 2-butanone, 1 -propanol, 2-propanol, DMSO, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, and butyl acetate. In some embodiments, the second organic solvent is isopropyl alcohol, acetone or a mixture of isopropyl alcohol and acetone. As with the first organic solvent, the solvent(s) selected for the second organic solvent(s) should not be highly reactive with the concentrated sulfuric acid and should not interact with the damaged/decomposed resin. Furthermore, if the optional second organic solvent is hydrophobic, the wafer is dried with a gas, such as with air, argon, nitrogen, or mixtures thereof.

[0044] Washing Away the Degraded Resin Coating with Water

[0045] Following the washing with the first organic solvent(s) and the optional washing with the second organic solvent(s), the resulting washed substrate is further washed with water to remove the first organic solvent(s) (and, if used, the second organic solvent(s)) and form a cleaned substrate substantially lacking the cured resin coating (or a reaction product thereof) and substantially lacking the degraded resin coating (or a reaction product thereof). Contaminants present on the substrate will also be removed from the organic solvent(s) washing and water washing steps. Where the first organic solvent(s) (and, if used, the second organic solvent(s)) is isopropyl alcohol, acetone or a mixture of isopropyl alcohol and acetone, the washing with water to remove the first organic solvent(s) (and, if used, the second organic solvent(s)) forms a cleaned substrate substantially lacking isopropyl alcohol and/or acetone.

[0046] The water may be purified water such as deionized (Dl) water, which is particularly desirable for electronics end uses. Where a nonpolar (or water immiscible) solvent is used for the second organic solvent washing step, the nonpolar solvent is desirably removed prior to washing with water. The removal can be, for example, by drying with air, argon, and/or nitrogen. [0047] Using the inventive methods of removing silicone resins from various substrates detailed herein, where the resin-coated substrate is soaked in the (i) concentrated sulfuric acid, the amount of resin residue remaining on the wafer following the soaking and washing steps using the sulfuric acid soaking concentration levels described herein is less than 0.20 wt.% and, in many instances, the silicone is completely removed from the wafer. In some instances, the amount of resin residue remaining on the wafer following the soaking and washing steps using the sulfuric acid soaking concentration levels described herein is 0.19 wt.% or less; in some embodiments, 0.18 wt.% or less; in other embodiments, 0.17 wt.% or less; in further embodiments, 0.16 wt.% or less; in still further embodiments, 0.15 wt.% or less; in some embodiments, 0.14 wt.% or less; in other embodiments, 0.13 wt.% or less; in further embodiments, 0.12 wt.% or less; in still further embodiments, 0.1 1 wt.% or less; in some embodiments, 0.10 wt.% or less; in other embodiments, 0.09 wt.% or less; in further embodiments, 0.08 wt.% or less; in still further embodiments, 0.07 wt.% or less; in some embodiments, 0.06 wt.% or less; in other embodiments, 0.05 wt.% or less; in further embodiments, 0.04 wt.% or less; in still further embodiments, 0.03 wt.% or less; in some embodiments, 0.02 wt.% or less; in other embodiments, 0.01 wt.% or less, based on weight of the cured resin coating; and in still further embodiments, 0 wt.% or less, based on weight of the cured resin coating.

[0048] Using the inventive methods of removing silicone resins from various substrates detailed herein, where the resin-coated substrate is soaked in the (ii) a mixture (e.g., solution) of concentrated sulfuric acid mixed with one or more organic compounds (the sulfuric acid-organic compound mixture), the amount of resin residue remaining on the wafer following the soaking and washing steps using the sulfuric acid soaking concentration levels described herein is less than 0.26 wt.% and, in many instances, the silicone is completely removed from the wafer. In some instances, the amount of resin residue remaining on the wafer following the soaking and washing steps using the sulfuric acid soaking concentration levels described herein is 0.25 wt.% or less; in some embodiments, 0.24 wt.% or less; in other embodiments, 0.23 wt.% or less; in some other embodiments, 0.22 wt.% or less; in further embodiments, 0.21 wt.% or less; in still further embodiments, 0.20 wt.% or less; in some embodiments, 0.19 wt.% or less; in some embodiments, 0.18 wt.% or less; in other embodiments, 0.17 wt.% or less; in further embodiments, 0.16 wt.% or less; in still further embodiments, 0.15 wt.% or less; in some embodiments, 0.14 wt.% or less; in other embodiments, 0.13 wt.% or less; in further embodiments, 0.12 wt.% or less; in still further embodiments, 0.1 1 wt.% or less; in some embodiments, 0.10 wt.% or less; in other embodiments, 0.09 wt.% or less; in further embodiments, 0.08 wt.% or less; in still further embodiments, 0.07 wt.% or less; in some embodiments, 0.06 wt.% or less; in other embodiments, 0.05 wt.% or less; in further embodiments, 0.04 wt.% or less; in still further embodiments, 0.03 wt.% or less; in some embodiments, 0.02 wt.% or less; in other embodiments, 0.01 wt.% or less, based on weight of the cured resin coating; and in still further embodiments, 0 wt.% or less, based on weight of the cured resin coating.

[0049] The inventive methods of removing silicone resins from various substrates are advantageous in that they provide high throughput and high speed of removal of the cured resin coating (and any reaction product thereof) and the degraded resin coating (and any reaction product thereof) from the substrate as the methods described herein facilitate wafer treating within only 2 or 3 hours, which is particularly desirable for electronics end uses. Additionally, the chemicals deployed in the inventive methods have minimal or no impact on the substrate (as concentrated sulfuric acid does not etch silicon or glass wafers) and are low cost (due to the ready availability of sulfuric acid).

[0050] Drying the Cleaned Substrate

[0051] The cleaned substrate (e.g., the substrate substantially lacking the cured resin coating (or a reaction product thereof) and substantially lacking the degraded resin coating (or a reaction product thereof)) may be dried with a gas such as with air, argon and/or nitrogen. Any other suitable methods used for drying substrate surfaces at a reasonable temperature in the microelectronics industry can also and/or alternatively be employed.

[0052] End Uses of the Washed, Cleaned and Dried Substrate

[0053] Depending on the requirement of the applications, the washed, cleaned and dried substrate may be directly used for subsequent processing steps or subjected to further cleaning processes known in the art and adopted in the microelectronics industry such as, but not limited to, RCA clean. The inventive methods readily facilitate removal of a cured silicone resin from a substrate for substrate reclaim.

EXAMPLES

[0054] All parts and percentages in the examples are on a weight basis and all measurements were indicated at about 23°C, unless indicated to the contrary. The dynamic viscosity of the uncured silicone resin was measured using a Brookfield LV DV-E Viscometer with an LV spindle probe. The test method used was ASTM D2196 and D1084. The dynamic viscosity of the uncured silicone was in the range of 1 ,000-20,000 cP.

[0055] The Comparative Examples (CE) that follow are not to be deemed prior art. They are non-invention examples that may help illustrate some advantages of the invention. The non- limiting examples listed below and labeled as Invention Example (Ex) that follow illustrate embodiments of the invention.

Comparative Examples (CE) 1 a-1 e: Film Forming on and Film Removal from Wafers: Effect of Sulfuric Acid Concentration on Silicone Resin Removal

[0056] A polydimethylsiloxane-based resin with a dynamic viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers. The thin film materials with thickness of around 50 μηι (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0057] The silicone resin-coated substrates were soaked in concentrated sulfuric acid (30 wt.% - 90 wt.%) at room temperature for 30 minutes, respectively. Afterwards, the wafers were first thoroughly washed with I PA and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone removed from CE 1 a-1 e (1 a to 1 e) was calculated as detailed below. The test results are reported later in Table 1.

[0058] The weight percent of silicone removed from the wafer was calculated using the following formula:

Wt% of Silicone Removed =—— ^-x 100%

W, - W _a

where W ₀ is the weight of the silicon wafer prior to spin coating, W-, is the weight of the silicon wafer after spin-coating with silicone; and W ₂ is the weight of the silicone-coated silicon wafer upon removal of the silicone. The residual silicone remaining on the wafer was calculated using the following formula:

Residua! Slfcone m sfer ^™ —— 100% where W ₀ is the weight of the silicon wafer prior to spin coating, W-, is the weight of the silicon wafer after spin-coating with silicone; and W ₂ is the weight of the silicone-coated silicon wafer upon removal of the silicone.

[0059] The test results for Comparative Examples CE 1 a-1 e reveal that, despite soaking of these substrates in concentrated sulfuric acid for 30 minutes each, virtually no silicone removal occurred at sulfuric acid concentration levels of 80 wt.% and below. Substantially increased, though not complete, silicone removal occurred at a sulfuric acid concentration level of 90 wt.%.

Invention Example (Ex) 1 : Film Forming on and Film Removal from a Wafer: Effect of Sulfuric Acid Concentration on Silicone Resin Removal

[0060] The protocol for CE 1 a-1 e was replicated except that the silicone resin-coated substrate of Ex 1 was soaked in a sulfuric acid concentration level of 96 wt.% at room temperature for 30 minutes. The test results are reported later in Table 1.

[0061] The test results for Invention Example Ex 1 reveal that complete (100 wt.%) silicone removal occurred at a sulfuric acid concentration level of 96 wt.%.

Table 1 : Effect of Sulfuric Acid Concentration on Removal of 50 urn Thick Silicone Resin

Film after Treatment with Concentrated Sulfuric Acid

Comparative Example (CE) 2a: Film Forming on and Film Removal from a Wafer: Effect of Sulfuric Acid Treatment Time on Silicone Resin Removal

[0062] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto a pre-weighed 4" silicon wafer. The thin film material with thickness of around 50 μηη (about 550 mg) was cured at 150°C. The wafer was further treated to 250°C for 1 hr as noted in Table 2. The wafer was weighed again after cure to calculate the amount of resin coated on the wafer for the silicone resin-coated substrate which was formed.

[0063] The silicone resin-coated substrate was soaked in concentrated sulfuric acid (about 96 wt.%) at room temperature for 5 minutes. Afterwards, the wafer was first thoroughly washed with I PA and then washed with Dl water. The wafer was weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated as detailed below. The test results are reported later in Table 2.

[0064] The test results for Comparative Example CE 2a reveal a silicone removal level above 0.20 wt.% following soaking in about 96 wt.% sulfuric acid after 5 minutes.

Invention Examples (Ex) 2a-2d: Film Forming on and Film Removal from Wafers: Effect of Sulfuric Acid Treatment Time on Silicone Resin Removal

[0065] The protocol for CE 2a was replicated except that for Invention Examples Ex 2a-2d, a polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto silicon wafers (Ex 2a-2c) and a glass wafer (Ex 2d), respectively. Additionally, the silicone resin- coated substrates (Ex 2a-2c) and the glass resin-coated substrate (Ex 2d) were soaked in concentrated sulfuric acid (about 96 wt.%) at room temperature for 10, 20, 15 and 15 minutes, respectively. Additionally, some of the wafers (Ex 2c-2d) were further treated to 250°C for 1 hr as noted in Table 2. The test results are reported later in Table 2.

[0066] The test results for Invention Examples Ex 2a-2b reveal a silicone removal level at less than 0.20 wt.% following soaking in about 96 wt.% sulfuric acid after 10 and 20 minutes, respectively. The test results for Invention Examples Ex 2c-2d reveal complete (100 wt.%) silicone removal following soaking in about 96 wt.% sulfuric acid after 15 minutes for the silicon wafer (Ex 2c) and after 15 minutes for the glass wafer (Ex 2d) and further treatment to

250°C for 1 hr, respectively.

Table 2: Efficiency of Removal of the 50 urn Thick Silicone Resin Film with

Concentrated Sulfuric Acid by Varying Treatment Time

Invention Example (Ex) 3a-3b: Film Forming on and Film Removal from Wafers: Effect of Washing Solvent on Silicone Resin Removal

[0067] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers. The thin film materials with thickness of around 50 μηη (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0068] The silicone resin-coated substrates were soaked in concentrated sulfuric acid (95 wt.% - 98 wt.% (i.e., 95 to 98 wt.%)) at room temperature for 30 minutes. Afterwards, the wafers were first thoroughly washed with I PA for Ex 3a and with acetone for Ex 3b as shown in Table 3 and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated according to the calculation detailed in CE 2 and Ex 2a-2d. The surface appearance of the wafers after solvent washing was noted. The test results are reported later in Table 3. [0069] The test results for Invention Examples Exs 3a-3b reveal complete (100 wt.%) silicone removal following soaking in concentrated sulfuric acid for 30 minutes and washing with both I PA as and acetone as the respective washing solvent.

Table 3: Effect of Washing Solvent on Removal of 50 urn Thick Silicone Resin

Film after Treatment with Concentrated Sulfuric Acid

Comparative Examples (CE) 4a-4c: Film Forming on and Film Removal from Wafers: Effect of Various Washing Solvents on Silicone Resin Removal

[0070] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers. The thin film materials with thickness of around 50 μηη (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0071] The silicone resin-coated substrates were soaked in concentrated sulfuric acid (95 wt.% - 98 wt.%) at room temperature for 30 minutes. Afterwards, the silicone resin-coated substrates were washed with ethanol and 1-pentanol or not washed at all and then washed with Dl water, respectively, as shown in Table 4. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated according to the calculation detailed in CE 2 and Ex 2a-2d. The surface appearance of the wafers after solvent washing was noted. The test results are reported later in Table 4.

[0072] The test results for Comparative Examples CE 4a-4c reveal a silicone removal level at 0.20 wt.% following soaking in 95 wt.% - 98 wt.% sulfuric acid for 30 minutes (for CE 4c) and a silicone removal level at slightly greater than 0.20 wt.% (0.30 wt.% following an ethanol wash for CE 4a and 0.80 wt.% following a 1-pentanol wash for CE 4b) following soaking in 95 wt.% - 98 wt.% sulfuric acid for 30 minutes.

Table 4: Effect of Washing Solvent on Removal of 50 um Thick Silicone Resin

Film after Treatment with Concentrated Sulfuric Acid

CE 4a 150°C/2 30 Ethanol 0.30 Obvious min Residue

CE 4b 150°C/2 30 1-Pentanol 0.80 Obvious min Residue

CE 4c 150°C/2 30 None 0.20 Obvious min Residue

Invention Examples (Ex) 5a-5c: Repeating/Reclaiming of Wafers after Removing the Silicone

Resin Multiple Times

[0073] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers and a glass wafer, respectively. The thin film materials with thickness of around 50 μηι (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0074] The silicone resin-coated substrates were soaked in concentrated sulfuric acid (about 96 wt.%) at room temperature for 30 minutes, respectively. Afterwards, the wafers were first thoroughly washed with I PA and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer.

[0075] After the wafers were subjected to the above cleaning process, the same wafers were subjected to the above coating and cleaning processes two additional times to demonstrate the reclaimability or reuseability of the wafers. The percentage of silicone removed from the wafer was calculated according to the calculation detailed in CE 1 a-1 e and Ex 1 . The test results are reported later in Table 5.

[0076] As shown in Table 5, the silicone removal methods in Invention Examples Ex 5a-5c facilitated the reclaimability of the wafers upon subjecting the wafers to multiple silicone removal and cleaning steps. Complete (100 wt.%) silicone removal was observed following soaking in about 96 wt.% sulfuric acid for 30 minutes and washing with I PA even with the three steps of coating the wafer with the silicone. The silicone removal methods did not change the properties of the wafer.

Table 5: Wafer Reclaim after Removing the Silicone Resin Multiple Times

Comparative Examples (CE) 6a-6d: Effect of Different Comparative Acids on Silicone Resin Removal

[0077] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers. The thin film materials with thickness of around 50 μηι (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0078] The silicone resin-coated substrates were soaked in selected acids shown below at room temperature for 120 minutes. Afterwards, the wafers were first thoroughly washed with I PA and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone removed from the wafer was calculated according to the calculation detailed in CE 1 a-1 e and Ex 1. The overall test results are reported later in Table 6.

[0079] As shown in Table 6, the test results for Comparative Examples Exs 6a-6d reveal virtually no silicone removal upon soaking in 65% nitric acid and 85% phosphoric acid, even with the soaking time extended to 120 minutes, and very limited silicone removal upon soaking in DYNASOLVE 218 and DIGESIL® NC Xtra (71.84 wt.% for CE 6a and 71 .79 wt.% for CE 6d), even with the soaking time extended to 120 minutes.

Table 6: Effect of Different Acids on Silicone Resin Removal

[0080] Comparative Examples (CE) 7a-3c: Film Forming on and Film Removal from Wafers: Effect of Different Sulfuric Acid-Organic Compound Mixtures on Silicone Resin Removal

[0081] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers. The thin film materials with thickness of around 50 μηι (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0082] The silicone resin-coated substrates were soaked at room temperature for 30 minutes in mixtures of 96 wt.% sulfuric acid/octane/4-dodecyl benzyl sulfonic acid at varying final concentrations as shown below for CE 7a-7c as listed in Table 7. Afterwards, the wafers were first thoroughly washed with I PA as shown in Table 7 and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated according to the calculation detailed in CE 2 and Ex 2a-2d. The surface appearance of the wafers after solvent washing was noted. The test results are reported later in Table 7.

[0083] As shown in Table 7, the test results for Comparative Examples Exs 7a-7c reveal very little silicone removal upon soaking in 4-dodecyl benzyl sulfonic acid alone (CE 7a), little silicone removal in the presence of an octane and 4-dodecyl benzyl sulfonic acid combination (CE 7b), and more significant, but not substantial enough, silicone removal in the presence of a 50 wt.% sulfuric acid and 50 wt.% 4-dodecyl benzyl sulfonic acid combination (CE 7c).

[0084] Invention Examples (Ex) 7a-7g: Film Forming on and Film Removal from Wafers: Effect of Different Sulfuric Acid-Organic Compound Mixtures on Silicone Resin Removal

[0085] The protocol for CE 7a-7c was replicated to form the respective silicone resin-coated substrates. The silicone resin-coated substrates were soaked at room temperature for 30 minutes in mixtures of 96 wt.% sulfuric acid/octane/4-dodecyl benzyl sulfonic acid at varying final concentrations as shown below for Ex 7a-7d and in mixtures of 96 wt.% sulfuric acid/tetradecane/4-dodecyl benzyl sulfonic acid at varying final concentrations as shown below for Ex 7e-7g in Table 7. Afterwards, the wafers were first thoroughly washed with I PA as shown in Table 7 and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated according to the calculation detailed in CE 2 and Ex 2a-2d. The surface appearance of the wafers after solvent washing was noted. The overall test results are reported below in Table 7.

[0086] As shown in Table 7, the test results for Invention Examples Exs 7a-7g reveal complete (100 wt.%) silicone removal (Exs 7c-7f) and virtually complete silicone removal (99.89 wt.% for Ex 7a, 99.93 wt.% for Ex 7b, and 99.91 wt.% for Ex 7g) upon soaking in mixtures containing a combination of sulfuric acid and an alkane having 5 or more carbons (here, octane and tetradecane) and, optionally, a sulfonic acid (here, 4-dodecyl benzyl sulfonic acid) where the total concentration of the sulfuric acid in the mixture is 20 wt.% or greater.

Table 7: Effect of Different Soaking Mixtures on Removal of 50 urn Thick Silicone Resin Film

[0087] Comparative Examples (CE) 8a-8b: Film Forming on and Film Removal from Wafers: Effect of Different Commercial Sulfuric Acid-Organic Compounds on Silicone Resin Removal

[0088] A polydimethylsiloxane-based resin with a viscosity of 5,000 cP was spin coated onto pre-weighed 4" silicon wafers. The thin film materials with thickness of around 50 μηι (about 550 mg) were cured at 150°C. All of the wafers were weighed again after cure to calculate the amount of resin coated on the respective wafers for the silicone resin-coated substrates which were formed.

[0089] The silicone resin-coated substrates were soaked at room temperature for 30 minutes in DYNASOLVE 218 (CE 8a) and DIGESIL® NC Xtra (CE 8b) as listed in Table 8. Afterwards, the wafers were first thoroughly washed with I PA as shown in Table 8 and then washed with Dl water. All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated according to the calculation detailed in CE 2 and Ex 2a-2d. The surface appearance of the wafers after solvent washing was noted. The test results are reported later in Table 8.

[0090] As shown in Table 8, the test results for Comparative Examples Exs 8a-b reveal little silicone removal upon soaking in Dynasolve 218 alone (CE 8a) and DIGESIL® NC Xtra alone (CE 8b).

[0091] Invention Examples (Ex) 8a-8n: Film Forming on and Film Removal from Wafers: Effect of Concentration of Different Commercial Sulfuric Acid-Organic Compounds on Silicone Resin Removal

[0092] The protocol for CE 8a-8b was replicated to form the respective silicone resin-coated substrates. The silicone resin-coated substrates were soaked at room temperature for 30 minutes in mixtures of either 96 wt.% sulfuric acid/DYNASOLVE 218 at varying final concentrations as shown below for Ex 8a-8g or 96 wt.% sulfuric acid/DIGESIL® NC Xtra at varying final concentrations as shown below for Ex 8h-8n in Table 8. Afterwards, the wafers were first thoroughly washed with I PA as shown in Table 8 and then washed with Dl water.

All of the wafers were weighed again to calculate the percentage of silicone removed from the wafer. The percentage of silicone residue remaining on the wafer was calculated according to the calculation detailed in CE 2 and Ex 2a-2d. The surface appearance of the wafers after solvent washing was noted. The test results are reported below in Table 8.

[0093] As shown in Table 8, the test results for Invention Examples Exs 8a-8n reveal complete (100 wt.%) silicone removal (Exs 8b-8g, 8k) and virtually complete silicone removal

(99.78 wt.% for Ex 8a, 99.75 wt.% for Ex 8h, 99.98 wt.% for Ex 8i, 99.98 wt.% for Ex 8j,

99.91 wt.% for Ex 8I, 99.89 wt.% for Ex 8m, and 99.93 wt.% for Ex 8n) upon soaking in a combination of sulfuric acid and either DYNASOLVE 218 or DIGESIL® NC Xtra (both mixtures of alkanes having 5 or more carbons and sulfonic acids) where the total concentration of the sulfuric acid in the mixture is 20 wt.% or greater.

Table 8: Effect of Different Soaking Mixtures on Removal of 50 um Thick

Silicone Resin Film

CE 8a 150°C/2 min None DYNASOLVE 218 100 I PA 34.01 Significant

Residue

CE 8b 150°C/2 min None DIGESIL® NC Xtra 100 I PA 31.50 Significant

Residue

Ex 8a 150°C/2 min None 96 wt.% sulfuric 20/80 I PA 0.22 Barely Seen acid/DYNASOLVE Residue 218

Ex 8b 150°C/2 min None 96 wt.% sulfuric 25/75 I PA 0.00 Shiny, Clean acid/DYNASOLVE

218

Ex 8c 150°C/2 min None 96 wt.% sulfuric 30/70 I PA 0.00 Shiny, Clean acid/DYNASOLVE

218

Ex 8d 150°C/2 min None 96 wt.% sulfuric 35/65 I PA 0.00 Shiny, Clean acid/DYNASOLVE

218

Ex 8e 150°C/2 min None 96 wt.% sulfuric 40/60 I PA 0.00 Shiny, Clean acid/DYNASOLVE

218

Ex 8f 150°C/2 min None 96 wt.% sulfuric 50/50 I PA 0.00 Shiny, Clean acid/DYNASOLVE

218

Ex 8g 150°C/2 min None 96 wt.% sulfuric 70/30 I PA 0.00 Shiny, Clean acid/DYNASOLVE

218

Ex 8h 150°C/2 min None 96 wt.% sulfuric 20/80 I PA 0.25 Barely Seen acid/DIGESIL® NC Residue Xtra

Ex 8i 150°C/2 min None 96 wt.% sulfuric 25/75 I PA 0.02 Shiny, Clean acid/DIGESIL® NC

Xtra

Ex 8j 150°C/2 min None 96 wt.% sulfuric 30/70 I PA 0.02 Shiny, Clean acid/DIGESIL® NC

Xtra

Ex 8k 150°C/2 min None 96 wt.% sulfuric 35/65 I PA 0.00 Shiny, Clean acid/DIGESIL® NC

Xtra

Ex 81 150°C/2 min None 96 wt.% sulfuric 40/60 I PA 0.09 Shiny, Clean acid/DIGESIL® NC

Xtra

Ex 8m 150°C/2 min None 96 wt.% sulfuric 50/50 I PA 0.1 1 Shiny, Clean acid/DIGESIL® NC

Xtra

Ex 8n 150°C/2 min None 96 wt.% sulfuric 70/30 I PA 0.07 Shiny, Clean acid/DIGESIL® NC

Xtra

[0094] Alternative Aspects

[0095] 1. A method of removing a cured resin coating from a resin-coated substrate formed of a substrate having the cured resin coating thereon, the method comprising: (a) soaking the resin-coated substrate in a sulfuric acid-based reagent for from greater than 0 to 60 minutes to degrade the cured resin coating on the substrate, wherein the resin of the cured resin coating is an Si-O-Si containing silicone resin and the sulfuric acid-based reagent is (i) an aqueous, concentrated sulfuric acid with a sulfuric acid concentration of at least 95 weight percent or (ii) a mixture of concentrated sulfuric acid mixed with one or more alkanes having 5 or more carbons such that the total sulfuric acid concentration of the mixture is at least 20 weight percent, wherein the concentrated sulfuric acid used to prepare the mixture (ii) has a starting concentration of at least 95 weight percent, (b) washing away the degraded resin coating from step (a) with a first organic solvent selected from isopropyl alcohol, acetone, 2- butanone, 1-propanol, 2-propanol, 1-butanol, 2-butanol, dimethyl sulfoxide, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether, or mixtures thereof to remove the degraded resin coating from the substrate; and (c) washing the substrate from step (b) with water to remove the first organic solvent and form a cleaned substrate substantially lacking the cured resin coating or a reaction product thereof and substantially lacking the degraded resin coating or a reaction product thereof, wherein the amount of any residue remaining on the cleaned substrate is less than 0.26 weight percent.

[0096] 2. The method according to aspect 1 , wherein the amount of any residue remaining on the cleaned substrate is less than 0.20 weight percent.

[0097] 3. The method according to aspect 1 or aspect 2, wherein the mixture of (ii) further includes an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, or any combination thereof.

[0098] 4. The method according to aspect 3, wherein the aromatic sulfonic acid is dodecyl benzenesulfonic acid, dodecyl benzenesulfonic acid salt, benzenesulfonic acid, benzenesulfonic acid salt, toluene sulfonic acid, toluene sulfonic acid salt, decyl benzyl sulfonic acid, decyl benzyl sulfonic acid salt, 4-dodecyl benzyl sulfonic acid, 4-dodecyl benzyl sulfonic acid salt, or any combination thereof.

[0099] 5. The method according to aspect 3 or 4, wherein the aliphatic sulfonic acid is methane sulfonic acid, methane sulfonic acid salt, ethane sulfonic acid, ethane sulfonic acid salt, butane sulfonic acid, butane sulfonic acid salt, decane sulfonic acid, decane sulfonic acid salt, dodecanesulfonic acid, dodecanesulfonic acid salt, or any combination thereof.

[00100] 6. The method according to any one of aspects 3 to 5, wherein the carboxylic acid is formic acid, formic acid salt, acetic acid, acetic acid salt, propionic acid, propionic acid salt, butanoic acid, butanoic acid salt, or any combination thereof.

[00101] 7. The method according to any one of the preceding aspects, wherein the cured resin coating is a cured Si-O-Si containing silicone resin and the resin-coated substrate is formed prior to step (a) by a method comprising: coating a curable Si-O-Si containing silicone resin onto the substrate to a resin coating thickness from greater than 0 millimeter up to about 1 millimeter to form a curable resin-coated substrate; and curing the curable Si- O-Si containing silicone resin to form a cured form of the resin-coated substrate.

[00102] 8. The method according to any one of the preceding aspects, further comprising a second washing step following step (b), wherein the second washing step involves washing with a second organic solvent, the second organic solvent is selected from an alkane, an aromatic hydrocarbon, a carboxylic ester, an alcohol, a ketone, an ether or mixtures thereof, wherein the second organic solvent is removed by drying with a gas prior to the washing step of step (c), wherein the drying involves the use of air, argon, nitrogen, or mixtures thereof.

[00103] 9. The method according to any one of the preceding aspects, wherein the first organic solvent is isopropyl alcohol or acetone.

[00104] 10. The method according to any one of the preceding aspects, wherein the resin of the cured resin coating is a curable resin containing the following structural unit:

R R

Si— O Si

R ^R wherein each R is independently an organic group selected from alkyl and aryl substituents.

[00105] 1 1. The method according to any one of the preceding aspects, wherein the resin of the cured resin coating is a polymer comprising macromolecules with Si-O-Si, wherein the Si-O-Si is part of backbones of the macromolecules.

[00106] 12. The method according to any one of the preceding aspects, wherein the substrate is coated with a protective layer that is highly non-reactive with the concentrated sulfuric acid and wherein the protective layer is disposed between the substrate and the Si- O-Si containing silicone resin of the cured resin coating.

[00107] 13. The method according to any one of the preceding aspects, wherein the Si-O-Si containing silicone resin of the cured resin coating has a thickness of from greater than 0 micron up to about 500 microns.

[00108] 14. The method according to any one of the preceding aspects, wherein the Si-O-Si containing silicone resin of the cured resin coating is a curable polydimethylsiloxane-based resin.

[00109] 15. The method according to any one of the preceding aspects, further comprising drying the substrate after step (c) with air, argon, nitrogen, or mixtures thereof.

[00110] 16. A method of removing a cured resin coating from a resin-coated substrate formed of a substrate having the cured resin coating thereon, the method comprising: (a) coating a curable Si-O-Si containing silicone resin onto the substrate to a resin coating thickness from greater than 0 millimeter up to about 1 millimeter to form a curable resin- coated substrate; (b) curing the curable Si-O-Si containing silicone resin to form a cured form of the resin-coated substrate; (c) soaking the cured form of the resin-coated substrate in a sulfuric acid-based reagent for from greater than 0 to 60 minutes to degrade the cured resin coating on the substrate, wherein the sulfuric acid-based reagent is (i) an aqueous, concentrated sulfuric acid with a sulfuric acid concentration of at least 95 weight percent or (ii) a mixture of concentrated sulfuric acid mixed with one or more alkanes having 5 or more carbons such that the total sulfuric acid concentration of the mixture is at least 20 weight percent, wherein the concentrated sulfuric acid used to prepare the mixture (ii) has a starting concentration of at least 95 weight percent; (d) washing away the degraded resin coating from step (c) with a first organic solvent selected from isopropyl alcohol, acetone, 2- butanone, 1-propanol, 2-propanol, 1-butanol, 2-butanol, dimethyl sulfoxide, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, and ethylene glycol dimethyl ether, or mixtures thereof to remove the degraded resin coating from the substrate; and (e) washing the substrate from step (d) with water to remove the first organic solvent and form a cleaned substrate substantially lacking the cured resin coating or a reaction product thereof and substantially lacking the degraded resin coating or a reaction product thereof, wherein the amount of any residue remaining on the cleaned substrate is less than 0.26 weight percent.

[00111] 17. The method according to aspect 16, wherein the amount of any residue remaining on the cleaned substrate is less than 0.20 weight percent.

[00112] 18. The method according to aspect 16 or aspect 17, wherein the mixture of (ii) further includes an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, or any combination thereof.

[00113] 19. A method of removing a cured resin coating from a resin-coated substrate formed of a substrate having the cured resin coating thereon, the method comprising: soaking the resin-coated substrate in a sulfuric acid-based reagent for from greater than 0 to 60 minutes to degrade the cured resin coating on the substrate, wherein the resin of the cured resin coating is a curable polydimethylsiloxane-based resin and wherein the sulfuric acid-based reagent is (i) an aqueous, concentrated sulfuric acid with a sulfuric acid concentration of at least 95 weight percent or (ii) a mixture of concentrated sulfuric acid mixed with one or more alkanes having 5 or more carbons such that the total sulfuric acid concentration of the mixture is at least 20 weight percent, wherein the concentrated sulfuric acid used to prepare the mixture (ii) has a starting concentration of at least 95 weight percent; washing away the degraded resin coating from step (a) with isopropyl alcohol, acetone or a mixture of isopropyl alcohol and acetone to remove the degraded resin coating from the substrate; and washing the substrate from step (b) with water to remove the isopropyl alcohol or the acetone and form a cleaned substrate substantially lacking the cured resin coating or a reaction product thereof and substantially lacking the degraded resin coating or a reaction product thereof, wherein the amount of any residue remaining on the cleaned substrate is less than 0.26 weight percent.

[00114] 20. The method according to aspect 19, wherein the amount of any residue remaining on the cleaned substrate is less than 0.20 weight percent.

[00115] 21. The method according to any one of the preceding aspects, wherein the mixture of (ii) further includes an aromatic sulfonic acid, an aromatic sulfonic acid salt, an aliphatic sulfonic acid, an aliphatic sulfonic acid salt, a carboxylic acid, a carboxylic acid salt, or any combination thereof.

[00116] 22. The method according to any one of the preceding aspects, wherein the resin- coated substrate is formed by a method comprising: coating a curable polydimethylsiloxane- based resin onto the substrate to a resin coating thickness from greater than 0 millimeter up to about 1 millimeter to form a curable resin-coated substrate; and curing the curable polydimethylsiloxane-based resin to form a cured form of the resin-coated substrate.

[00117] 23. The method according to any one of the preceding aspects, wherein the substrate is a silicon wafer, a silicon plate, a glass wafer, a glass plate, a silicon carbide wafer, a silicon carbide plate, a patterned silicon wafer, a patterned glass wafer, a patterned silicon carbide wafer, a device wafer, or a device plate.

[00118] 24. The method according to any one of the preceding aspects, wherein the water is purified water.

[00119] 25. The method according to any one of aspects 1 to 15 or aspects 19-24, wherein the soaking step (a) comprises soaking the resin-coated substrate in the sulfuric acid-based reagent for from greater than 0 to 60 minutes to degrade the cured resin coating on the substrate, wherein the resin of the cured resin coating is an Si-O-Si containing silicone resin and the sulfuric acid-based reagent is the (i) an aqueous, concentrated sulfuric acid with a sulfuric acid concentration of at least 95 weight percent.

[00120] 26. The method according to any one of aspects 1 to 15 or aspects 19-24, wherein the soaking step (a) comprises soaking the resin-coated substrate in the sulfuric acid-based reagent for from greater than 0 to 60 minutes to degrade the cured resin coating on the substrate, wherein the resin of the cured resin coating is an Si-O-Si containing silicone resin and the sulfuric acid-based reagent is the (ii) a mixture of concentrated sulfuric acid mixed with one or more alkanes having 5 or more carbons such that the total sulfuric acid concentration of the mixture is at least 20 weight percent, wherein the concentrated sulfuric acid used to prepare the mixture (ii) has a starting concentration of at least 95 weight percent.

[00121] While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.