CONTAINING ALUMINUM

RELATED APPLICATIONS [0001] This application claims benefit of U.S. Provisional Application No. 62/349,333, entitled "CLEANING COMPOSITIONS FOR MICROELECTRONIC SUBSTRATES CONTAINING ALUMINUM" filed on June 13, 2016, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] This invention pertains to cleaning and stripping compositions for microelectronic substrates and particularly for cleaning metal-containing residues from aluminum-containing microelectronics components without causing undue aluminum corrosion.

BACKGROUND

[0003] During the manufacture of microelectronic devices photoresists are employed to transfer images to a microelectronic substrate to create the desired circuit layer. Many of the

microelectronic devices are metallized with aluminum. Such microelectronic substrates may also be composed of and/or employ metals such as titanium, titanium nitride, tungsten and the like as adhesion promoters and diffusion barriers.

[0004] Many alkaline microelectronic stripping and cleaning compositions have been proposed for the removal of cross-linked and hardened photoresists and other residues, such as post etch residues, from such microelectronic substrates. However, one problem with such stripping and cleaning composition is the possibility of metal corrosion occurring as a result of the use of such cleaning compositions. Such corrosion results in whiskers, pitting, notching of metal lines, due at least in part to the reaction of the metals in the device substrates with the alkaline strippers employed. One such alkaline microelectronic stripping and cleaning composition is that disclosed in U.S. Pat. No. 5,308,745. While the stripping and cleaning compositions of that patent have been commercially employed to strip hardened and cross-linked photoresist from substrates, it has been discovered that attempts to clean microelectronic substrates having aluminum metallization and containing residues of metals from layers such as layers of titanium, titanium nitride, tungsten and the like, with the cleaning composition of this patent has resulted in significant aluminum corrosion or insufficient cleaning of the metal residues. Therefore, there is a limitation on the use of the cleaning compositions of that patent in the cleaning of vias that punch-through underlying layers of titanium, titanium nitride, tungsten and the like.

[0005] Currently the semiconductor cleaning market for aluminum technologies is dominated by hydroxylamine (HA) and/or n-methyl-pyrrolidone (NMP) based chemistries. For safety, health, and cost reasons, the semiconductor industry is moving away from NMP and HA chemistries. Such technology is exemplified in U.S. Patent No. 8,178,482, which discloses stripping and cleaning compositions including N-methyl pyrrolidone (NMP). NMP is on the special health hazard substance list, and can adversely affect an employee when accidentally inhaled or absorbed through the skin, causing headache, stomach pain, nausea, and vomiting. NMP also may be a teratogen, i.e., a substance which could cause malformation of an embryo to a pregnant person. There therefore is a need for HA and NMP free cleaning compositions and methods that are effective at removing residue as well as negative and positive bulk photoresist from semiconductor devices containing Al.

[0006] There is therefore a need for microelectronic stripping and cleaning compositions that can effectively remove such metal residues and do so without any significant aluminum corrosion resulting from the stripping and cleaning composition. There is also a need for stripping and cleaning compositions that, in addition to cleaning these metal residues, will also effectively clean post-ash residues from other vias and from metal lines, as well as cleaning unashed photoresist residue from the substrate. There is also a need for such compositions which are free from NMP, HA, and other environmentally harmful and/or toxic substances.

SUMMARY

[0007] In accordance with this invention, there are provided stripping and cleaning compositions for cleaning microelectronics substrates, the composition including: about 30% to about 50 % by weight ethylene glycol butyl ether, about 20% to about 30% by weight sulfolane, about 10% to about 45% by weight monoethanolamine, about 3% to about 15% by weight diethylene glycol, about 0.5% to about 10% dihydroxybenzene, and about 0.5% to about 50% water. The compositions may additionally comprise one or more components such as metal- complexing/corrosion resisting compounds, other corrosion inhibitors and surfactants. [0008] In an embodiment, the composition of the invention is used for stripping and cleaning substrates containing aluminum. In an embodiment, the substrates include an aluminum metallized substrate having vias and containing metal residue. In another embodiment, the metal residue includes at least one layer selected from the group consisting of titanium and titanium nitride layers. In another embodiment, the stripping and cleaning compositions include about 35% to about 45% by weight ethylene glycol butyl ether, about 24% to about 27% by weight sulfolane, about 13% to about 15% by weight monoethanolamine, about 4% to about 10% by weight diethylene glycol, about 3% to about 8% of a dihydroxybenzene, and about 9% to about 13% water.

[0009] In an embodiment, the composition is used for stripping and cleaning substrates containing aluminum. In an embodiment, the inventive composition is substantially free of hydroxylamine. In yet another embodiment, the inventive composition is substantially free of n- methylpyrrolidone (NMP).

[0010] In another embodiment, the present invention includes a method for cleaning

microelectronic substrates without producing any substantial corrosion to an aluminum substrate, the process comprising contacting the substrate with a cleaning composition for a time sufficient to clean the substrate, wherein the cleaning composition comprises about 30% to about 50 % by weight ethylene glycol butyl ether, about 20% to about 30% by weight sulfolane, about 10% to about 45% by weight monoethanolamine, about 3% to about 15% by weight diethylene glycol, about 0.5% to about 10% dihydroxybenzene, and about 0.5% to about 50% water.

[0011] The method for cleaning microelectronic substrates according to this invention comprises a method for cleaning microelectronic substrates without producing any substantial metal corrosion, the substrate containing at least one photoresist polymeric material, etch residues and metal residues, the process comprising contacting the substrate with a cleaning composition for a time sufficient to clean the substrate, wherein the cleaning composition includes: about 30% to about 50 % by weight ethylene glycol butyl ether, about 20% to about 30% by weight sulfolane, about 10% to about 45% by weight monoethanolamine, about 5% to about 15% by weight diethylene glycol, about 0.5% to about 10% dihydroxybenzene, and about 0.5% to about 50% water. [0012] The compositions may additionally comprise one or more components such as metal- complexing/corrosion resisting compounds, other corrosion inhibitors and surfactants. The method of cleaning microelectronic substrates in accordance with this invention is particularly useful for cleaning substrate that comprises an aluminum metallized substrate having vias and containing metal residue, and in an embodiment the metal residue is from at least one of layers of titanium and/or titanium nitride.

DETAILED DESCRIPTION

[0013] The invention also relates to cleaning of vias that punch through metal layers of microelectronics components, such as titanium or titanium nitride layers, while being compatible with underlying aluminum structures, i.e., causing little or no metal corrosion in the

microelectronics components. The invention further relates to such cleaning compositions that also are able to clean post-ash residue from other vias and from metal lines as well as cleaning or stripping unashed photoresist from microelectronics substrates. A further aspect of this invention is a process of cleaning or stripping photoresist and residue from aluminum-containing microelectronics components without causing undue aluminum corrosion.

[0014] Dihydroxybenzene, as used herein, includes catechol, also known as pyrocatechol or 1,2- dihydroxybenzene, and has molecular formula of C ₆ H4(OH)2. It is the ortho isomer of the three isomeric benzenediols. About 20 million kg are now synthetically produced annually as a commodity organic chemical, mainly as a precursor to pesticides, flavors, and fragrances.

Derivatives of catechol may also be used, including 3-methylcatechol, 4-methylcatechol, and 4- tertbutylcatechol.

[0015] The compositions of this invention may also optionally contain other additional components. Such optional additional components include metal-complexing/corrosion resisting compounds, other corrosion inhibitors and surfactants.

[0016] Organic or inorganic chelating or metal complexing agents/corrosion inhibitors are not required, but may optionally be included in the compositions of this invention, but offer substantial benefits, such as for example, improved product stability when incorporated into the aqueous cleaning compositions of this invention. Examples of suitable chelating or complexing agents include but are not limited to trans- 1,2-cyclohexanediamine tetraacetic acid (CyDTA), ethylenediamine tetraacetic acid (EDTA), stannates, pyrophosphates, alkylidene-diphosphonic acid derivatives (e.g. ethane- 1 -hydroxy- 1,1-diphosphonate), phosphonates containing ethylenediamine, diethylenetriamine or triethylenetetramine functional moieties [e,g.

ethylenediamine tetra(methylene phosphonic acid) (EDTMP), diethylenetriamine

penta(methylene phosphonic acid), triethylenetetramine hexa(methylene phosphonic acid). The chelating agent will be present in the composition in an amount of from 0 to about 5 wt %, preferably from about 0.1 to about 2 wt % based on the weight of the composition.

[0017] The aqueous cleaning compositions of this invention can also optionally contain other corrosion inhibitors and similar non-corrosive components employed in microelectronic cleaner compositions. The compounds may include resorcinol, gallic acid, propyl gallate, pyrogallol, hydroquinone, benzotriazole and derivatives of benzotriazole, and polyfunctional carboxylic acids such as citric acid, tartaric acid, gluconic acid, saccharic acid, glyceric acid, oxalic acid, phthalic acid, maleic acid, mandelic acid, malonic acid, lactic acid, and salicylic acid. These other corrosion inhibitors may be present in any suitable amount, generally in an amount of from about 0 to about 5 wt %, preferably from about 0.1 to about 3 wt %, and more preferably from about 0.2 to about 2 wt %.

[0018] The compositions of the present invention may also optionally contain any suitable water-soluble amphoteric, non-ionic, cationic or anionic surfactant. The addition of a surfactant will reduce the surface tension of the formulation and improve the wetting of the surface to be cleaned and therefore improve the cleaning action of the composition. The surfactant may also be added to reduce aluminum corrosion rates if further aluminum corrosion inhibition is desired. Amphoteric surfactants useful in the compositions of the present invention include betaines and sulfobetaines such as alkyl betaines, amidoalkyl betaines, alkyl sulfobetaines and amidoalkyl sulfobetaines; aminocarboxylic acid derivatives such as amphoglycinates, amphopropionates, amphodiglycinates, and amphodipropionates; iminodiacids such as alkoxyalkyl iminodiacids or alkoxyalkyl iminodiacids; amine oxides such as alkyl amine oxides and alkylamido alkylamine oxides; fluoroalkyl sulfonates and fluorinated alkyl amphoterics; and mixtures thereof.

[0019] Preferably, the amphoteric surfactants are cocoamidopropyl betaine, cocoamidopropyl dimethyl betaine, cocoamidopropyl hydroxy sultaine, capryloamphodipropionate,

cocoamidodipropionate, cocoamphopropionate, cocoamphohydroxyethyl propionate, isodecyloxypropylimino dipropionic acid, laurylimino dipropionate, cocoamidopropylamine oxide and cocoamine oxide and fluorinated alkyl amphoterics. Non-ionic surfactants useful in the compositions of the present invention include acetylenic diols, ethoxylated acetylenic diols, fluorinated alkyl alkoxylates, fluorinated alkylesters, fluorinated polyoxyethylene alkanols, aliphatic acid esters of polyhydric alcohols, polyoxyethylene monoalkyl ethers, poiyoxyethylene diols, siloxane type surfactants, and alkylene glycol monoalkyl ethers. Preferably, the non-ionic surfactants are acetylenic diols or ethoxylated acetylenic diols. Anionic surfactants useful in the compositions of the present invention include carboxylates, N-acylsarcosinates, sulfonates, sulfates, and mono and diesters of orthophosphoric acid such as decyl phosphate.

[0020] Preferably, the anionic surfactants are metal-free surfactants. Cationic surfactants useful in the compositions of the present invention include amine ethoxylates,

dialkyldimethylammonium salts, dialkylmorpholinum salts, alkylbenzyldimethylammonium salts, alkyltrimethylammonium salts, and alkylpyridinium salts. Preferably, the cationic surfactants are halogen-free surfactants. Example of especially suitable surfactants include, but are not limited to 3,5-dimethyl-l-hexyn-3-ol (Surfynol-61), ethoxylated 2,4,7, 9-tetramethyl-5- decyne-4,7-diol (Surfynol-465), polytetrafluoroethylene cetoxypropylbetaine (Zonyl FSK), Zonyl FSH, Triton X-100, namely octylphenoxypolyethoxyethanol, and the like. The surfactant will generally be present in an amount of from 0 to about 5 wt %, preferably 0.001 to about 3 wt % based on the weight of the composition.

EXAMPLES

[0021] The present invention is further exemplified, but not limited, by the following representative examples, which are intended to illustrate the invention and are not to be construed as being limitations thereto.

Example 1

Formulation A of the present invention:

Dihydroxy benzene 5%

[0022] Important components for aluminum compatibility are MEA and water. Additionally, catechol is an important component for removal of residue and photoresist.

Example 2

[0023] The closest prior art, represented by U.S. Patent No. 5,308,745 includes a composition comprising a stripping solvent, a nucleophilic amine and a non-nitrogen containing weak acid in an amount sufficient to neutralize from about 19% to about 75% by weight of the nucleophilic amine. Data was collected to show adding acid (acetic acid) to the formulation of our invention does not contribute to photoresist stripping performance. In comparison to a composition with Catechol is specifically required to contribute to photoresist and residue removal performance.

[0024] The wafers tested included bulk photoresist on aluminum. The wafers were all processed in solutions at 65°C, for 20 minutes, and at 650 RPM. Cleaning was observed via SEM.

Solutions tested:

A: 40% EGBE, 25.4% Sulfolane, 5% DEG, 14% MEA, 10.6% Water, 5%

dihydroxybenzene (Inventive composition)

B: 51% NMP; 23% MEA; 13.28% DEG; 10% Water; 2.72% Acetic Acid (prior art comparative example)

C: 51% NMP; 23% MEA; 11.5% DEG; 10% Water; 5.5% Acetic Acid (prior art comparative example)

D. 24% DMSO; 46% MEA; 10% DEG; 10% Water; 10% Acetic Acid (prior art comparative example)

E. 24% DMSO; 46% MEA; 15% DEG; 10% Water; 5% Acetic Acid (prior art comparative example)

TABLE 1

D Poor

E Poor

[0025] Results of the composition performance are seen in Table 1. Irrespective of solvent, it is apparent dihydroxybenzene is required for cleaning performance. Addition of just a neutralizing acid, such as acetic acid to the solutions containing NMP and DMSO results in poor cleaning performance.

Example 3

[0026] Similarly close prior art is represented by U.S. Patent No. 8,178,482, which describes compositions consisting of: about 20% to about 80 wt % of the composition of N-methyl pyrrolidone, monoethanolamine in an amount of from about 10% to about 45% based on the weight of the composition, from about 5% to about 15% by weight of the composition of diethylene glycol as a metal removing compound, catechol in an amount sufficient to neutralize from about 3% to about 75% by weight of the monoethanolamine such that the stripping composition has an aqueous pH of from about 9.6 to about 10.9, and water. The data below shows by removing catechol and using a mix of EGBE and Sulfolane a cleaner can be obtained that can strip bulk photoresist just as well, shows improved cleaning for aluminum substrates, and does not have the environmental and health hazards associated with NMP.

[0027] For Al cleans, the semiconductor industry typically requires a solution to be able to clean a wide variety of processes. 5 different types of wafers were used to compare cleaning of different systems. The goal here was primarily to look at impact of different solvent systems.

[0028] Wafers tested included bulk photoresist without metal exposed, bulk photoresist with Al exposed, thin organic residue on Al, thick organic residue on Al, and Al via cleans. The wafers were all processed in solutions at 65°C, for 20 minutes, at 650 RPM. Cleaning was observed via SEM.

Solutions tested:

A. 40% EGBE, 25.4% Sulfolane, 5% DEG, 14% MEA, 10.6% Water, 5%

dihydroxybenzene

F. 50% Sulfolane, 23% MEA, 12% DEG, 10% water, 5% catechol

G. 50% EGBE, 23% MEA, 12% DEG, 10% water, 5% catechol 46% NMP, 23% MEA, 10% DEG, 15% water, 5% Catechol

TABLE 2

[0029] High levels of EGBE are effective at cleaning some residues in vias that NMP and Sulfolane chemistries cannot clean. Bulk PR removal requires the presence of either Sulfolane or NMP. Optimal cleaning solution for both bulk PR as w ell as most residue removal is a mix of high percentage of EGBE with some sulfolane. Catechol and MEA are required for all these cleans.

[0030] Thus while there have been described what are presently believed to be preferred embodiments of the invention, those skilled in the art will realize that changes and modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as fall within the true scope of the invention.