CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of Provisional Patent Application No.

62/202,641, filed on August 7, 2015, which is incorporated by reference herein.

BACKGROUND

FIELD OF THE INVENTION

[0002] The invention relates to reducing plasma damage in dielectric materials. RELATED ART

[0003] In an integrated circuit, transistors are connected by tiny copper wires called interconnects or vias. Interlayer dielectric materials are used to separate adjacent metallic lines. The proximity of these copper lines causes capacitance between them. As

semiconductor manufacturers move to smaller nodes, the capacitance between adjacent lines increases, causing delay in the circuit.

[0004] To prevent this capacitance delay, low dielectric constant materials may be used to reduce capacitance at a given spacing. State of the art \ow-k materials are made with as many non-polarizable bonds as possible, such as C-C, C-H, Si-C, Si-O, or Si-H. To further decrease the dielectric constant, porosity is introduced, since air / vacuum has a low dielectric constant of ~l .

[0005] Unfortunately, porosity in the \ow-k dielectric layer causes problems during integration. In particular, damage due to plasma etch increases with porosity. The goal of this invention is to provide a method to reduce damage to the \ow-k layer during plasma etch, post-etch clean, and barrier layer / Cu deposition.

Integration Steps and Patterning

[0006] To connect layers of an integrated circuit, it is necessary to form interconnects during the integration process. To do this, it is generally necessary to follow a series of steps that can include but are not limited to hard mask deposition, plasma etch, post-etch clean, pore seal, liner deposition, and Cu deposition, among others. Many of these steps can have a negative impact on the properties of the \ow-k film. Plasma Etch Damage

[0007] In a dual damascene process, a plasma dry etch is used to form trenches and vias in the previously deposited \ow-k dielectric material. The plasma etch process often (but not exclusively) uses fluorocarbon plasma (C4F8, CF4, CFIF3, etc.) combined with other gases such as Ar / N2 / He/H ₂ and 0 ₂ . The radicals, UV radiation, and other by-products cause damage to the \ow-k film, and this damage is increased due to the increased surface area caused by the porosity included in the \ow-k film. The damage alters the bonding in the \ow-k material, breaking stable, non-polarizable bonds and forming more reactive, polar bonds such as Si-F or Si-OH. These polar groups increase the dielectric constant of the \ow-k dielectric and leakage current vs. the original film. They are also hydrophilic. Adsorbed water further increases the dielectric constant vs. the pristine film. Furthermore, the damaged material can be lost during post-plasma etch wet cleans, causing a loss of fidelity to the original pattern. These two problems present a substantial hindrance that must be overcome to successfully integrate a \ow-k dielectric material into an integrated circuit.

Background Approaches

[0008] Damage to \ow-k films during plasma etch has been widely recognized as an issue during integration and a number of approaches have been taken to solve it. These approaches can variously be summarize as: 1) after plasma etch, pore damage repair using reactive molecules or by generating reactive molecules in-situ with ultraviolet excitation; 2) pore filling with organic polymers to prevent diffusion of plasma gases into the films, and 3) after plasma etch, pore sealing with reactive species that can bind to the pore surface.

Pore Repair

[0009] Numerous molecules with a variety of functional groups have been used to repair pores after plasma etch. These approaches have primarily used methyl- terminal groups but a variety of reactive functional groups have been used to bind to the damaged matrix material. One of the first approaches to pore repair used hexamethyldisilazane [Texas Instruments, US Patent 20040152296 Al]. Other approaches have used acetoxy or alkoxysilanes [Hacker, Thomas, Drage, METHOD TO RESTORE HYDROPHOBICITY IN DIELECTRIC FILMS AND MATERIALS, US Patent 7,029,826 B2(2006)], in particular methyltriacetoxysilane.

Dialkylaminosilanes, such as bis(dimethylamido)dimethylsilane represent another way to attach methyl groups to damaged film (Chakrapani, Colburn, Dimitrakopoulos, Nitta, Pfeiffer, Purushothaman WO Patent 2006/049595(2006) (IBM)], as do cyclic amino compounds like N-trimethylsilylpiperidine or N-trimethylsilylpyrrolidine. [McAndrew, Anderson, Dussarat US Patent 8999734, CYCLIC AMINO COMPOUNDS FOR LOW-K SILYLATION]. What all these approaches have in common is that they use a highly reactive but integration compatible functional group to bind methylsilanes to damaged \ow-k bonds.

[0010] Another method to repair \ow-k damage is to use less reactive precursors and irradiate them with UV light to assist bond formation. To date, this approach has used gas phase precursors. In one method, a short application of low- wavelength UV light at high temperature was used to seal pores with ethylene, acetylene, 1,3 -butadiene, and isoprene [Yim, Nowak, Xie, Demos, US Patent 8,216,861 B l (2012) DIELECTRIC RECOVERY OF PLASMA DAMAGED LOW-K FILMS BY UV-ASSISTED PHOTOCHEMICAL DEPOSITION]. Another approach was to bind silylating molecules such as bis(dimethylamino)dimethylsilane using a higher wavelength, cold plasma [Varadarajan, McLaughlin, van Schravendijk, CARBON CONTAINING LOW-K DIELECTRIC CONSTANT RECOVERY USING UV

TREATMENT US 8,465,991 B2 (2013)].

Pore Filling & Removal

[001 1] Unlike pore repair, the pore filling approach seeks to prevent plasma damage by limiting diffusion of the etch gases into the \ow-k pores. This is done by coating the surface of a fully-cured low-k dielectric layer with an organic polymer and then heating the film so the polymer melts and infiltrates the pores. The residual material on the surface or overburden is removed, most commonly by a solvent rinse. Finally, the polymer is removed from the film via thermal annealing. C.F.

1. Frot, T. et al "Application of the Protection/Deprotection Strategy to the Science of Porous Materials" Adv. Mater. 2011, 23, 2828-2832.

2. Theo Frot , Willi Volksen , Sampath Purushothaman , Robert L. Bruc , Teddie

Magbitang , Dolores C. Miller , Vaughn R. Deline , and Geraud Dubois. "Post Porosity Plasma Protection: Scaling of Efficiency with Porosity, "Adv Fund. Mat. 2012, 22, 3043-3050.

3. Bruce, Dubois, Frot, Volksen US 8,927,430 B2 (2015), OVERBURDEN REMOVAL FOR PORE FILL INTEGRATION APPROACH Pore Sealing

[0012] Another form of an unwanted effect that can occur during integration of a \ow-k film is diffusion of a liner material into the pore wall when it is deposited into the vias or trenches post-plasma etch. This can be avoided by sealing the pore walls to prevent movement of the material from the trench into the low-k. Pore sealing has been carried out using plasma bombardment to modify the \ow-k material as well as vapor- and liquid- phase deposition of capping layers.

[0013] For pores with small neck sizes, several plasma sealing approaches have been taken to seal the pore surface. In general, these techniques have been applied to seal small pores (<0.7 nm radius) produced by chemical vapor deposition. In one method, bias was increased in an etch tool using either He/N ₂ or Ar/N ₂ until ellipsometric porosimetry showed that toluene could no longer penetrate the film [Abell, Maex. Microelectron. Eng. 2004, 76, 16-19. DAMAGE MINIMIZED PLASMA PORE SEALF G OF MICROPOROUS LOW-K DIELECTRICS]. In other work, an Ar/0 ₂ plasma was used to similar effect [Chang, Pan, Chen. Microelectron. Eng. 2009, 86, 2241]. This plasma was hypothesized to produce a dense Si0 ₂ -like layer. A dense Si0 _2- like pore seal layer could also be made using UV-ozone [Caroline M. Whelana, Quoc Toan Lea, Francesca Cecchet, Alessandra Satta, Jean- Jacques Pireaux, Petra Rudolf, and Karen Maex. Electrochem. Solid-State Lett. 2004, 7, F8-F10. Sealing of Porous Low-k Dielectrics. Ellipsometric Porosimetry Study of Formula Oxidized Formula Films.]

[0014] An alternative approach is to apply a separate capping layer by either gas-phase or liquid phase process. One example of a gas phase process is the application of a thin layer of t-butoxysilanol and a trimethylaluminum catalyst by ALD [de Rouffignac, Li, Gordon. ECS Letters 2004, 7, G306-G308 "Sealing Porous Low-k Dielectrics with Silica." Other examples are spin-on materials such as hexaethoxytrisilacyclohexane and other carbosilane oligomers[Van Driessche A new procedure to seal the pores of mesoporous low-k films with precondensed organosilica oligomers. Chem. Commun., 2012,48, 2797-2799; Michalak, Blackwell, Biefeld, Clarke et al. US Patent App 2013/0320520 Al CHEMICALLY ALTERED CARBOSILANES FOR PORE SEALING APPLICATIONS].

[0015] All of the publications, patents and patent applications listed in the foregoing paragraphs are incorporated by reference herein. SUMMARY

[0016] In one aspect, a method of protecting a pore of a pore-containing low-k dielectric material is provided (called "Permanent Resident"), where the dielectric material is disposed over a substrate, and the pore is defined by a pore wall. The method includes: prior to plasma etching of the dielectric material, depositing one or more organosilicon compounds onto the pore wall, each organosilicon compound including at least one plasma-protective functional group that resists plasma damage and at least one reactive functional group that attaches to the pore wall; and reacting the at least one reactive functional group with the pore wall to produce a protective coating on the pore wall prior to plasma etching of the dielectric material.

[0017] In the method: a) each organosilicon compound can be an organosilane compound; b) the at least one plasma-protective functional group can be an alkyl, aryl, arylalkyl, or alkenyl group, or a polyhedral oligomeric silsesquioxane (POSS) moiety; c) the at least one reactive functional group can be a hydrido, hydroxyl, alkoxy, acyl, halogen, or dialkylamino silane group; d) each organosilicon compound can have the formula (I), (II) or (III):

R ¹ R ¹ R ¹

I i I

R ² - Si - X R ² — Si — X Z— Si - X

(I) (ID (H I)

where,

R ¹ . R ² and R ³ are each independently alkyl, aryl, arylalkyl, or alkenyl, or a POSS moiety; and

X, Y and Z are each independently

where R is alkyl, aryl or arylalkyl; in some embodiments, the POSS moiety has the formula (R"SiOi _. 5)n, where n is 8, 10 or 12, where one R" is a hydrocarbon group forming a bond with the Si atom of formula (I), (II) or (III), and where each remaining R" is independently hydrogen, or an alkyl, alkenyl, alkynyl, aryl, arylalkyl, cycloalkyl, or cycloalkenyl group; e) the depositing can include depositing each organosilicon compound in solution in a solvent; f) the reacting can include heating the one or more organosilicon compounds deposited onto the pore wall, in some embodiments, the heating is in the range of about 80 °C to about

400 °C; g) plasma etching the low-k dielectric material after producing the protective coating; or h) any combination of a) - g). The protecting coating can be described as a silicon- containing protective coating.

[0018] In another aspect, a low-k dielectric material disposed over a substrate is provided. The dielectric material includes pores defined by pore walls, and each pore wall includes a protective coating prepared by the method of protecting a pore of a pore-containing low-k dielectric material.

[0019] In a further aspect, a method of protecting a pore of a pore-containing low-k dielectric material disposed over a substrate is provided (called "Pore Filling"), where the pore is defined by a pore wall. The method includes: prior to plasma etching of the dielectric material, depositing one or more organosilicon compounds onto a surface of the dielectric material, each organosilicon compound including a polyhedral oligomeric silsesquioxane (POSS) compound; and filling the pore with the one or more organosilicon compounds prior to plasma etching of the dielectric material.

[0020] In the method: a) the POSS compound can be a T ₈ , T ₁₀ , or T ₁₂ POSS compound; b) the POSS compound can be fully condensed or partially condensed; c) the POSS compound can have the formula (R'"SiOi.5) _n , where n is 8, 10 or 12, and where each R" is independently hydrogen, alkyl, alkenyl, alkynyl, aryl, arylalkyl, cycloalkyl, or cycloalkenyl; d) only one R'" is an arylalkyl group; e) the one or more organosilicon compounds can be deposited as a solid or a liquid, or a combination thereof; f) the filling can include heating the one or more organosilicon compounds deposited onto the surface of the dielectric material; in some embodiments, the heating is in the range of about 80 °C to about 400 °C; g) plasma etching the low-k dielectric material after pore filling; or h) any combination of a) - g).

[0021] In another aspect, a low-k dielectric material disposed over a substrate is provided. The dielectric material includes filled pores, each pore being filled by the Pore Filling method of protecting a pore of a pore-containing low-k dielectric material described above. [0022] In a further aspect, a method of protecting a pore of a pore-containing low-k dielectric material disposed over a substrate is provided (called "Pore Sealing"), where the pore is defined by a pore wall. The method includes: after plasma etching of the dielectric material, depositing one or more organosilicon compounds onto the pore wall, each organosilicon compound including at least one reactive functional group that reacts with a reactive group produced in the dielectric material by the plasma etching, and further including at least one crosslinkable group or at least one bulky group that is larger than -CH ₃ , or a combination thereof; and reacting the at least one reactive functional group with the reactive group produced by the plasma etching to form a coating on the pore wall.

[0023] In the method: a) each organosilicon compound can be an organosilane compound, or can be an organosilicate oligomer, which can be formed by hydrolysis and polymerization of a silicon compound, or can be a polyhedral oligomeric silsesquioxane (POSS) compound, which can be a T ₈ , T ₁₀ , or T ₁₂ POSS compound; b) the at least one reactive functional group can be a hydrido, hydroxyl, alkoxy, acyl, halogen, or dialkylamino silane group; c) the at least one crosslinkable group or bulky group can be an alkyl, aryl, arylalkyl, alkenyl, or a polyhedral oligomeric silsesquioxane (POSS) moiety; d) each organosilicon compound can have the formula (I), (II) or (III):

R ¹ R ¹ R ¹

I I I

Si - X R ² — Si — X Z— Si

I I I

(I) (ID (H i) where,

R ¹ . R ² and R ³ are each independently alkyl, aryl, arylalkyl, or alkenyl, or a POSS moiety; and

X, Y and Z are each independently where R is alkyl, aryl or arylalkyl; in some embodiments, the POSS moiety has the formula (R"SiOi.5)n, where n is 8, 10 or 12, where one R" is a hydrocarbon group forming a bond with the Si atom of formula (I), (II) or (III), and where each remaining R" is independently hydrogen, or an alkyl, alkenyl, alkynyl, aryl, arylalkyl, cycloalkyl, or cycloalkenyl group; e) the depositing can include depositing each organosilicon compound in solution; f) the reacting can inlcude heating the one or more organosilicon compounds deposited onto the pore wall, or UV illuminating the one or more organosilicon compounds deposited onto the surface of the pore, or a combination thereof; g) the coating can increase modulus and/or hardness of the dielectric material compared to the dielectric material before coating; or h) any combination of a) - g). After coating the pore, the dielectric material can be subject to further processing such as deposition of a barrier layer, Cu deposition, or further processing of the dielectric material after producing the coating. The coating can be described as a silicon-containing coating.

[0024] In another aspect, a low-k dielectric material disposed over a substrate is provided. The dielectric material includes pores defined by pore walls, each pore wall comprising a coating prepared by the Pore Sealing method of protecting a pore of a pore-containing low-k dielectric material disposed over a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a panel of Fourier transform infrared (FTIR) spectra of a low-k film after HB, PhBuSi(OAc) ₃ PDM, and 10 min at 400 °C under N ₂ .

[0027] Figure 2 is a panel of FTIR spectra of another low-k film after HB, PhSi(OAc) ₃ PDM, and 10 min at 400 °C under N ₂ .

[0028] Figure 3 is a schematic drawing of pore coating and pore sealing examples.

[0029] Figures 4A-4D are schematic drawings of reactions of silicon compounds in pores.

[0030] Figures 5A-5C are schematic drawings of permanent residence, pore sealing and pore filling processes, respectively.

[0031] Figure 6 is a table providing stress test results of a dielectric material. [0032] Figure 7 is another table providing stress test results of a dielectric material. DETAILED DESCRIPTION

[0033] One or more chemical groups are included in different embodiments.

[0034] As used herein, the term "alkyl" refers to a branched or unbranched saturated hydrocarbon group such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. In some embodiments, the alky group is a C ₁ -C24 alkyl group, or a C4-C ₁₆ alkyl group .

[0035] The term "aryl" refers to an aromatic hydrocarbon group containing a single aromatic ring or multiple aromatic rings that are fused together, linked covalently, or linked to a common group such as a methylene or ethylene moiety. In some embodiments, aryl groups contain one aromatic ring or two fused or linked aromatic rings, e.g., phenyl, naphthyl, biphenyl, diphenylether, diphenylamine, benzophenone, and the like. In some embodiments, the aryl group is a C ₆ -Ci ₈ aryl group.

[0036] The term "alkenyl" refers to a branched or unbranched hydrocarbon group and at least one double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, and the like, as well as cycloalkenyl groups such as cyclobuienyl, cyclopentenyl and cyciohexenvl. and the like. In some embodiments, the alkenyl group is a C2-C24 alkenyl group, or a C4-C ₁₀ alkenyl group.

[0037] The term "arylalkyl," refers to an aryl group terminating with an aliphatic group, such as a benzyl, phenylethyl, phenylpropyl, phenylbutyl group, and the like. In some embodiments, the aryl portion is a C ₆ -Ci ₈ aryl and the alkyl portion is a Ci- C _i8 alkyl.

[0038] The term "alkoxy" refers to an alkyl group bound through a single, terminal ether linkage; that is, an "alkoxy" group may be represented as -O-alkyl where alkyl is as described above. Similarly, the term "aryloxy" refers to an aryl group bound through a single, terminal ether linkage, where aryl is as described above. The term "acyloxy" refers to the group -0-C(0)R, where R is an alkyl, aryl or arylal kyl group as described above. The term "acyr refers to the group -C(Q)R, where R is an alkyl, aryl or arylalkyl group as described above.

[0039] A dialkylamino silane has the formula R ₂ NSH ₃ , where R can be a C ₁ -C ₁₀ alkyl group. [0040] A polyhedral oligomeric silsesquioxane has the empirical formula [RSiOi sh, where n = 6-24, and R can be hydrogen, alkyl, alkenyl, alkynyl, aryl, arylalkyl, cycloalkyl, cycloalkenyl, heterocycloalkyl, or heterocycloalkenyl. Polyhedral oligomeric silsesquioxanes can form open structures or closed, cage-like structures, such as in the shape of cubes, hexagonal prisms, octagonal prisms, and decagonal and dodecagonal prisms. A polyhedral oligomeric silsesquioxane can be fully condensed or partially condensed. In some embodiments, n = 8, 10 or 12.

Characterization of Plasma Etch Damage

[0041] Plasma damage characterization techniques are necessary to determine the efficiency of different plasma damage mitigation approaches. These techniques include chemical removal of the damage layer, FTIR spectroscopy to show changes in the chemical makeup of the bulk film due to plasma damage, and electrical measurements to determine figures of merit such as dielectric constant and breakdown voltage.

Plasma-Induced Damage Layer Determination

[0042] Exposure to aggressive plasma breaks organic bonds and converts the surface into an Si0 ₂ -like material which is vulnerable to dissolution in dilute hydrofluoric acid. Blanket \ow-k films are deposited on a substrate. The films are either left pristine or coated with a plasma-damage reduction layer. The coupons are placed in a process boat, dipped in dilute (pref. 0.5 wt%) dHF for 5 min followed by DI water for 1 min. Thickness and RI are measured pre- and post-dHF etch. The loss due to dissolution is known as the "plasma- induced damage layer."

[0043] In some aspects, three types of embodiments are provided for plasma damage management (PDM) of dielectric materials. These embodiments can be applied to improve the performance of computing devices with microprocessors that contain integrated circuits packaged within a die or dies. In some implementations, the integrated circuit die contains devices such as transistors or interconnects that are separated by porous \ow-k material.

Permanent Resident Approach

[0044] In the first approach, which is called "Permanent Resident," prior to etch, the pore walls of the \ow-k material can be coated with a silane that has a plasma-protective functional group and a reactive functional group to bind to the low-k matrix. The plasma protective group can work in two ways: first, it can be less susceptible to plasma etch than the \ow-k material. Second, the by-products produced by its reaction with the plasma gases can be less polar and less reactive than the matrix. Therefore, changes in dielectric constant, leakage current, and material loss during post-etch clean can be minimized by the use of this material. Uniquely, this material can remain during the entire integration process with minimal impact on k

[0045] When designing the permanent resident molecule, the molecule chosen has one or more plasma damage resistant functional groups such as, but not limited to, alkyl, phenyl, phenyl-alkyl, vinyl, allyl, alkene, or silicone. Some examples include, but are not limited to, butyl, octyl, isooctyl, octadecyl, vinyl, 1-butenyl, 1-octenyl, 4-phenyl ethyl, 4-phenylbutyl, and phenyl. In addition, the molecule chosen has one or more reactive functional groups, such as, but are not limited to, acetoxy, methoxy, chloro-, hydrido-, ethoxy-, tbutoxy-, hydroxyl- or dialkylamino-silanes. These groups react with the \ow-k matrix and/or themselves to permanently attach the plasma damage resistant group to the \ow-k pore wall.

[0046] The formulation and plasma resistant molecule can meet one or several features for integration, including having a small impact on k (<0.1), thermal stability for further integration steps (preferably up to about 400 °C for 10 min), and/or a small impact on the plasma etch rate.

[0047] In some embodiments, the silane can have one of the following formulas (I), (II) or (III):

R ¹ R ¹ R ¹

I I I

St - X ² — Si — X Z— Si

I I I

(I) (I D (I II) where X, Y and Z are each independently OR, CI

R where R can be methyl, ethyl, a propyl isomer, a butyl isomer, phenyl, benzyl, phenyl alkyl, and the like.

[0048] In these embodiments, R ¹ . R ² and R ³ each independently can be: a) an alkyl such as, but not limited to, methyl, ethyl, a propyl isomer, a butyl isomer, and the like; b) an aryl such as, but not limited to, phenyl, naphthyl, biphenyl, anthracenyl, phenanthrenyl, and the like; c) an aryl alkyl such as, but not limited to, benzyl, phenylethyl, phenylpropyl, phenylbutyl, naphthylalkyl, biphenylalkyl, anthracenylalkyl, phenanthrenylalkyl, and the like; d); a cage organosilicate oligomer, commonly known as POSS, such as T ₈ , T ₁₀ , T ₁₂ embodiments, which correspond to the number of 8, 10, 12 Si atoms in the cage. In these embodiments, the POSS compounds can have pendant functional groups where one or more of the groups is chemically inequivalent to the other groups. Examples include, but are not limited to, R7S18O12CH2-, R7S18O12CH2CH2-, R7SisOi2(CH2)nCH2- , where n = 1-18, and the like. An example of a POSS compound of this embodiment is:

[0049] After being deposited onto a pore wall, an organosilicon compound can be reacted with the pore wall by heating in the range of about 80 °C to about 400 °C for about 0.5 minutes to about 30 minutes. This can be accomplished by a one- or two-step process. For example, in a two-step process, heating in the range of about 80 °C to about 200 °C can occur as the first step, and heating in the range of about 200 °C to about 400 °C can occur in the second step. In one embodiment, an about 150 °C 2 minute hot-plate bake followed by an about 400 °C oven bake for 10 minutes can be employed. In another embodiment, an about 150 °C 2 minute hot-plate bake followed an about 300 °C oven bake for 2 minutes can be employed, Additional bakes may be added to further stabilize the film if higher subsequent process temperatures are to be used. The ambient environment for the heat treatment can be air or an inert environment, such as in nitrogen, argon, helium, a vacuum, and the like.

[0050] An organosilicon compound can be deposited, for example, by spin coating, dipping into a solution of the silicon compound in an organic solvent, spray coating such a solution, or vapor deposition.

[0051] Examples of organic solvents that can be used for deposition of the silicon compounds include, but are not limited to, n-butyl acetate, tetrahydrofuran, propylene glycol methyl ether acetate (PGMEA), and the like.

[0052] In some embodiments, two or more of the organosilicon compounds can be deposited onto the pore wall.

[0053] Silicon molecules attached to the pore wall can remain and strengthen the film after etch. Any decomposition products may be removed, for example, with a post etch clean process that employs solvent to remove etch residue and heating to above 300 °C but below 500 °C, or by exposing to UV light and heat.

Pore Filling Approach

[0054] In the second approach, the pores of the \ow-k dielectric can be filled, partially or completely, with an organosilicate material prior to plasma etch. Because the pores are filled, plasma gases cannot readily diffuse into the \ow-k dielectric, reducing the damage to the surface of the trench or via. In some embodiments, the pore filler used is an organosilicate oligomer similar to the matrix. Unlike organic polymers previously used for this purpose, the pore filler can be thermally stable to high temperatures, which may be necessary during the hard mask process. Additionally, due to the similarity to the matrix material, etch and clean recipes similar to those used on the unprotected matrix can be used.

[0055] Suitable molecules can be selected from Polyhedral Oligomeric Silsesquioxanes (POSS). Particular examples include, but are not limited to: octakis(isobutyl)POSS

(1,3,5,7,9, 11, 13, 15-Octakis(isobutyl)pentacyclo[9.5.1.13,9.15, 15.17, 13]octasiloxane), octakis(isooctyl)POSS (1,3, 5,7,9,11, 13, 15-

Octakis(isooctyl)pentacyclo[9.5.1.13,9.15,15.17,13]octasi loxane), phenylbutyl-heptaphenyl- POSS, (l-(4-phenylbutyl)-3,5,7,9, l l,13, 15-phenylpentacyclo- [9.5.1.13,9.15, 15.17, 13]octasiloxane), isooctyl-heptaphenylPOSS and aminopropyl- heptaphenylPO S S ( 1 -(3 -aminopropyl)-3 ,5,7,9,11, 13, 15 -phenylpentacyclo- [9.5.1.13,9.15, 15.17, 13]octasiloxane). The molecules can be selected based on their thermal and plasma stability, solubility, and glass transition temperatures.

[0056] In some embodiments, the POSS molecule can be an arylalkylPOSS, which can be a T ₈ , Tio, To embodiment. Examples of such molecules include, but are not limited to, phenylbutylheptaphenyl POSS, phenylbutylheptamethyl POSS, other T ₈ derivatives, and the like. In some embodiments, the POSS molecule is

where R can be: a) an alkyl such as, but not limited to, methyl, ethyl, a propyl isomer, a butyl isomer, and the like; b) an aryl such as, but not limited to, phenyl, naphthyl, biphenyl, anthracenyl, phenanthrenyl, and the like; c) an aryl alkyl such as, but not limited to, benzyl, phenylethyl, phenylpropyl, phenylbutyl, naphthylalkyl, biphenylalkyl, anthracenylalkyl, phenanthrenylalkyl, and the like.

[0057] In some embodiments, the molecule can be a cage organosilicate oligomer with pendant functional groups all the same such as

[0058] where R can be: a) an alkyl such as, but not limited to, methyl, ethyl, a propyl isomer, a butyl isomer, and the like; b) an aryl such as, but not limited to, phenyl, naphthyl, biphenyl, anthracenyl, phenanthrenyl, and the like; c) an aryl alkyl such as, but not limited to, benzyl, phenylethyl, phenylpropyl, phenylbutyl, naphthylalkyl, biphenylalkyl, anthracenylalkyl, phenanthrenylalkyl, and the like.

[0059] In some embodiments, the molecule can be a partially condensed cage

organosilicate oligomer, including T ₈ , T ₁₀ , or T ₁₂ embodiments. Examples of the partially condensed molecules include, but are not limited to: a) Disilanol POSS (T8) derivatives such as, but not limited to, disilanolmethyl POSS, disilanol ethyl POSS, disilanolcyclohexyl POSS, disilanolphenyl POSS, and disilanolisobutyl POSS. For example, the disilanol POSS can be

b) Trisilanol POSS (T8) derivatives such as, but not limited to, trisilanolmethyl POSS, trisilanolethyl POSS, trisilanolcyclohexyl POSS, trisilanolphenyl POSS, and

trisilanolisobutyl POSS. For example, the trisilanol POSS can be

c) Tetrasilanol POSS (T8) derivatives such as, but not limited to, tetrasilanolmethyl POSS, tetrasilanolethyl POSS, tetrasilanolcyclohexyl POSS, tetrasilanolphenyl POSS, and tetrasilanolisobutyl POSS. For example, the tetrasilanol POSS can be

[0060] For these di-, tri- and tetrasilanol POSS derivatives, R can be: a) an alkyl such as, but not limited to, methyl, ethyl, a propyl isomer, a butyl isomer, and the like; b) an aryl such as, but not limited to, phenyl, naphthyl, biphenyl, anthracenyl, phenanthrenyl, and the like; c) an aryl alkyl such as, but not limited to, benzyl, phenylethyl, phenylpropyl, phenylbutyl, naphthylalkyl, biphenylalkyl, anthracenylalkyl, phenanthrenylalkyl, and the like.

[0061] For filling, a deposited organosilicon compound can be heated in a range of about 80 °C to about 400 °C for about 0.5 minutes to about 30 minutes.

[0062] For an organosilicon compound that is insoluble in a preferred coating solvent, or gives a pore coating as a solution, the compound can be deposited in a solid form (for example, isobutyl POSS and trisilanol-iBu POSS). Solid POSS materials can be heated, for example, at about 150 °C for about 10 minutes to give satisfactory fill. Some POSS materials which are mixtures of 8, 10 and 12 membered cages are viscous liquids. These materials can be coated directly without added solvent.

[0063] In some embodiments, two or more of the organosilicon compounds can be deposited onto the dielectric material and fill the pore.

[0064] Silicon molecules filling the pore may be removed with a post etch clean process that employs solvent to remove etch residue and heating to above 300 °C but below 500 °C, or by exposing to UV light and heat. Pore Sealing Approach

[0065] In the third approach to preventing plasma damage, after plasma etch, the pore surface is sealed with a thin layer of organosilicate material that simultaneously repairs the heavily damaged surface layer (reacting with the polar damaged groups to make a less polar bond that does not affect k substantially). The pore sealing can prevent the diffusion of the electromigration barrier layer and copper infiltration of the \ow-k dielectric when it is filled- into the trenches and vias that were plasma etched. The pore sealing layer can be selected to have one or more features such as a minimal thickness (< 2nm), low k impact (<0.1), and/or to be thermally stable to 400 °C. Furthermore, the pore sealing layer can be chosen so that it can react with and repair damaged layers without penetrating/reacting with the undamaged layer of the film. The compounds can be deposited by spin-coating a solution onto a \ow-k film that has already had vias and trenches formed in it by plasma etching. In some cases, the surface tension or polarity of the solvent can be chosen to prevent infiltration of the pores beyond the damaged surface layer.

[0066] Solutions for sealing can contain molecules or oligomers that have reactive functional groups such as, but not limited to, acetoxy, methoxy, chloro-, hydrido-, ethoxy-, tbutoxy-, hydroxyl- or dialkylamino-silanes. In the case of individual molecules, they can also contain a bulky or crosslinkable functional group that blocks the pores, such as, but not limited to, alkyl, phenyl, phenyl-alkyl, vinyl, allyl, alkene, or silicone. The oligomers can contain such a group but are also intrinsically bulky. Particular examples of suitable molecules for pore sealing include 1-butenyltriacetoxysilane, 1, 1-divinyldiacetoxysilane, phenylmethyldiacetoxysilane, phenyltriacetoxysilane, and octylmethyldiacetoxysilane. Particular examples of oligomers include sols/oligomers of tetraethoxysilane,

methyltriethoxysilane, methyl bis(triethoxysilane). After the solution is deposited, a soft-bake to evaporate solvent or further bind the material may be applied, and/or an ultraviolet exposure with or without heat may also be applied to further crosslink the pore sealing layer.

[0067] In some embodiments, the molecules for sealing can have one of the following formulas (I), (II) or (III): R ¹ R ¹ R ¹

I I I

Si - X R ² — Si — X Z— Si ^■

I I I

R ³ Y

(I) (I I) (in) where X, Y and Z are each independently

OH, , OR, CI

R where R can be methyl, ethyl, a propyl isomer, a butyl isomer, phenyl, benzyl, phenyl alkyl, and the like.

[0068] In these embodiments, R ¹ . R ² and R ³ each independently can be: a) an alkyl such as, but not limited to, methyl, ethyl, a propyl isomer, a butyl isomer, and the like; b) an aryl such as, but not limited to, phenyl, naphthyl, biphenyl, anthracenyl, phenanthrenyl, and the like; c) an aryl alkyl such as, but not limited to, benzyl, phenylethyl, phenylpropyl, phenylbutyl, naphthylalkyl, biphenylalkyl, anthracenylalkyl, phenanthrenylalkyl, and the like; d); a cage organosilicate oligomer, commonly known as POSS, such as T ₈ , T ₁₀ , To embodiments, which correspond to the number of 8, 10, 12 Si atoms in the cage. In these embodiments, the POSS compounds can have pendant functional groups where one or more of the groups is chemically inequivalent to the other groups. Examples include, but are not limited to, R7S18O12CH2-, R7S18O12CH2CH2-, R7SisOi2(CH2)nCH2- , where n = 1-18, and the like. An example of a POSS compound of this embodiment is:

[0069] After deposition, an organosilicon compound can be heated in the range of about 80 °C to about 400 °C for about 0.5 minutes to about 30 minutes. This can be accomplished by a one- or two-step process as described above for the Permanent Resident approach. UV irradiation can be performed, for example, with a mercury lamp under an inert atmosphere or vacuum with low levels of oxygen. Exposure time can be about 05 min to about 20 minutes, and can be less than about 10 minutes.

[0070] An organosilicon compound can be deposited, for example, by spin coating, dipping into a solution of the silicon compound in an organic solvent, spray coating such a solution, or vapor deposition.

[0071] Examples of organic solvents that can be used for deposition of the silicon compounds include, but are not limited to, n-butyl acetate, tetrahydrofuran, propylene glycol methyl ether acetate (PGMEA), and the like.

[0072] In some embodiments, two or more of the organosilicon compounds can be deposited onto the pore wall.

[0073] Silicon molecules attached to pore walls by the Pore Sealing approach can seal the pores for subsequent deposition of a barrier layer.

[0074] Referring now to Fig. 3, various ways an organosilicon compound can attach to a pore wall as part of the Permanent Resident approach or the Pore Sealing approach are described. Although not wishing to be bound by theory, it is believed that Fig. 3 describes reactions and processes that can occur inside a pore of a pore-containing dielectric material.

[0075] Fig. 4 describes various ways an organosilicon compound can attach to a pore wall and react within a pore as part of the Permanent Resident approach or the Pore Sealing approach. Although not wishing to be bound by theory, it is believed that Fig. 4 describes reactions and processes that can occur inside a pore of a pore-containing dielectric material. In Fig. 4A, reactions of various silane compounds are described. In Fig. 4B, reactions of trifunctional molecules with pore walls having 2 or 3 available silanols is described. In Fig. 4C, reactions of trifunctional molecules with a pore wall having 1 available silanol is described. Fig. 4D describes reactions of trifunctional molecules when a pore wall has no available silanol.

[0076] Fig. 5 describes ways to practice embodiments of the methods. Although not wishing to be bound by theory, it is believed that Fig. 5 also describes the results of practicing the embodiments. Fig. 5A relates to the Permanent Resident approach. Fig. 5B relates to the Pore Sealing approach. Fig. 5C relates to the Pore Filling approach.

[0077] The present invention may be better understood by referring to the accompanying examples, which are intended for illustration purposes only and should not in any sense be construed as limiting the scope of the invention.

EXAMPLE 1

PERMANENT RESIDENT Octylmethyldiacetoxysilane (OMDAS)

[0078] 1 mL of between 0.5 - 2 wt % solution in either THF or PGMEA was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. For a 500 nm thick film of -35% porosity, 1.0 wt. % was applied in PGMEA. FTIR showed the presence of methylene groups. For a 90 nm thick film, an 0.5% loading was required to achieve the same refractive index. After the permanent resident was applied, ARI = 0.03. The plasma etch rate was minimally effected, being 187 ±3 nm vs 200 ± 5 nm for an untreated sample. Meanwhile, the plasma induced damaged layer was only 13 ±2 nm vs 25 ± 5 nm for an untreated sample, suggesting a 50% reduction in plasma damage with the OMDAS material. The OMDAS permanent resident had minimal impact on the electrical properties of the film. A Ak = 0.04 ± 0.02 was obtained after application. The breakdown voltages were -1.82 MV / cm vs. -1.83 MV/cm for an untreated film. Ellipsometric porosimetry gave a total porosity of 26.2 %, a pore radius of 1.38 nm, and a neck size of 1.54 nm.

[0079] Additional data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1. 4-Phenylbutyltriacetoxysilane

[0080] 1 mL of between 0.5 - 1 wt% solution in either THF or PGMEA was spun onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. For a 500 nm thick film of -35% porosity, 1.0% was applied in PGMEA. FTIR showed the presence of methylene and phenyl groups, as shown in Figure 1. After the permanent resident was applied, ARI = 0.04±0.001. The plasma damaged layer measured by dFIF dissolution was 14 ±2 nm vs 25 ± 5 nm for an untreated film. Thermal stability up to 400 C for 10 min was confirmed by the remaining methylene and phenyl peaks in the FTIR.

4-Phenylethyltriacetoxysilane

[0081] 1 mL of between 0.5 - 5 wt % solution in THF was spin-cast onto fully cured low- k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

Octyltriacetoxysilane

[0082] 1 mL of 1-5% solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the low-& film can be found in Table 1. Ellipsometric porosimetry obtained on films coated with an 0.5 wt % solution gave a porosity of 22.3 %, pore radius of 1.49 nm, and a pore neck of 1.59 nm. z ^' so-Octyltriacetoxysilane

[0083] 1 mL of between 1 - 5 wt % solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1. Octadecyltriacetoxysilane

[0084] 1 mL of 1 wt% solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

Octadecylmethyldiacetoxysilane

[0085] 1 mL of 1 wt% solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

7-Octenyltriacetoxysilane

[0086] 1 mL of 1-5 wt% solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

Phenyltriacetoxysilane

[0087] 1 mL of 1 wt% solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 4 min soft-bake at 150 C. Solution concentration depended on film thickness and porosity. FTIR showed the presence of phenyl stretches as well as additional cage structure in the Si0 ₂ peak, as shown in Figure 2. After heating for 10 min at 400 C under N ₂ , these peaks remained, indicating the thermal stability of this compound in the pores.

PORE FILLING iso-ButylPOSS

(1,3,5,7,9, 11,13, 15 Octakis(isobutyl)pentacyclo[9.5.1.13,9.15, 15.17, 13]octasiloxane) [0088] Concentrated powder was applied to the surface of a fully cured low-k film and heated to 150 C for 10 min to melt it into the film. The remaining powder was removed from the surface.

[0089] The pore filler could be removed from the film by either solvent rinses or a thermal treatment. Solvent rinses with THF, butyl acetate, and toluene were most effective at removing the pore filler and restoring the original k. For low-& films with an original k of 2.16, the final k value after pore filling and removal via toluene rinse was 2.24.

[0090] Iso-butyl POSS proved highly effective at reducing the plasma damage layer, so the loss was only 20% of that obtained on the control films. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the low-& film can be found in Table 1. isoOctylPOSS

(1,3,5,7,9, 11, 13, 15-Octaisooctyl)pentacyclo[9.5.1.13,9.15,15.17,13]octasiloxa ne)

[0091] A droplet of viscous liquid was applied to the surface of a fully cured low-k film and heated to 150 C for 10 min to melt it into the film. The remaining liquid was removed from the surface. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the low-& film can be found in Table 1. isoOctylphenylPOSS

( 1 -i sooctyl)-3 ,5,7,9,11, 13, 15 -phenylpentacyclo- [9.5.1.13,9.15,15.17,13] octasil oxane)

[0092] 1 mL of 0.5-2 wt% solution in THF was spin-cast onto fully cured low-k films on Si substrate with a geometry of lxl inch at 1500 RPM for 90s, followed by a 10 min soft- bake at 250 C. For a 2 wt% loading, ellipsometric porosimetry gave a porosity of 11.9%, and substantially reduced pore radius of 0.48 nm and neck of 0.46 nm, indicating substantial pore filling.

Trisilanol-isoButylPOSS

(1,3,5,7,9, 1 l,14-Heptaisobutyltricyclo[7.3.3.15,1 l]heptasiloxane-3,7,14-triol)

[0093] Concentrated powder was applied to the surface of a fully cured low-& film and heated to 150 °C for 10 min to melt it into the film. The remaining powder was removed from the surface. [0094] Trisilanol-IbuPOSS proved highly effective at reducing the plasma damage layer. Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

Trisilanol-isoOctylPOSS

(l,3,5,7,9, l l,14-Heptaisooctyltricyclo[7.3.3.15,l l]heptasiloxane-3,7, 14-triol)

[0095] Concentrated powder was applied to the surface of a fully cured \ow-k film and heated to 150 °C for 10 min to melt it into the film. The remaining powder was removed from the surface.

[0096] Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

OctamethylPOSS

(1,3,5,7,9, 11,13, 15 Octamethyl)pentacyclo[9.5.1.13,9.15, 15.17, 13]octasiloxane

[0097] Concentrated powder was applied to the surface of a fully cured \ow-k film and heated to 150 °C for 10 min to melt it into the film. The remaining powder was removed from the surface.

[0098] Data on the effects of this permanent resident on the plasma damage layer, plasma etch rate, and refractive index of the \ow-k film can be found in Table 1.

Tetrasilanol-PhPOSS

[0099] Concentrated powder was applied to the surface of a fully cured \ow-k film and heated to 150 °C for 10 min to melt it into the film. The remaining powder was removed from the surface.

PLASMA ETCH

[00100] Plasma etch was carried on an Oxford Instruments Plasmalab Viper parallel -plate etcher. A C ₄ F ₈ / 0 ₂ / Ar plasma recipe was used.

[00101] Table 1 lists the plasma protective properties of permanent resident materials applied to \ow-k dielectric films, plasma etched, and plasma damaged layer removed by dHF. TABLE 1 Characterization of Low-k Films

Isooctyl- 1% in THF 1.30 60s 1.30 178 15.95 triacetoxysilane 5% in THF 1.39 1.37 145 12.61

Trisilanol- Cone. 1.41 60s 1.39 136.4 4.20 Isobutyl-POSS 90s 1.40 208.2 3.9

Trisilanol- Cone. 1.30 90s 1.29 278.4 16.6 Isooctyl-POSS

Octa-lsobutyl- Cone. 1.40 60s 1.38 142.6 6.83 POSS 90s 1.38 210.0 6.7

Octamethyl-POSS Cone. 1.31 60s 1.27 179.4 18.72

90s 1.28 243.0 23.2

Isooctyl-POSS Cone. 1.33 60s 1.33 241.1 12.09

Standard 60s 1.27 190.4 27.4

Standard 90s 1.27 296.2 22.6

PORE SEALING Phenylbutyltriacetoxysilane

[00102] 0.1% Phenylbutyltriacetoxysilane in PGMEA was spun onto a dehydrated \ow-k film at 1500 RPM for 90 s and soft-baked for 2 min at 150 °C. The pore seal layer thickness was 2 ± 1 nm and no refractive index change was observed in the underlying \ow-k, indicating the pore seal did not penetrate far into the film. Ellipsometric porosimetry with IP A and a 10 s delay between pressure steps showed that the poreneck size decreased from

0.8 nm for an unsealed sample to 0.6 nm for the PhBu-treated sample. Furthermore, hysteresis between the adsorption and desorption branches of the porosimetry isotherms increased from 0.08 to 0.14, indicating slower diffusion of IP A into the film. This further confirmed that phenylbutyltriacetoxysilane sealed the surface of the film.

EXAMPLE 2

PREPARATION OF COMPOUNDS

1. «-Octadecyldimethylacetoxysilane

[00103] 5.00g (14.6mmol) of «-Octadecyldimethylmethoxysilane, 1.86g (18.2mmol) of Acetic Anhydride and 1.37g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and stirred under N2 blanket for lh at 110-115°C. The warm reaction mixture is decanted from Dowex resin, and subjected to vacuum distillation of the side products (lh at 50→110°C, P 50mm Hg), giving 4.24g (78%) of I - uncolored transparent viscous liquid, which solidifies on cooling. Its structure is confirmed by FTIR and 1H NMR.

2. Trivinylacetoxysilane

[00104] 5.00g (35.7mmol) of Trivinylmethoxysilane, 4.55g (44.6mmol) of Acetic

Anhydride and 1.91g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in a 50mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 110-115°C. The reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (lh at 80→90°C, P 50mm Hg), giving 4.45g (74%) of uncolored transparent liquid stored in refrigerator. Its structure is confirmed by FTIR and 1H NMR. 3. «-Octylmethyldiacetoxysilane

[00105] 5.00g (22.9mmol) of «-Octylmethyldimetoxysilane, 5.84g (57.2mmol) of Acetic Anhydride and 2.17g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 115-125°C. The reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (lh at 80→90°C, P 55mm Hg), giving 5.28g (84%) of uncolored transparent liquid. Its structure is confirmed by FTIR and 1H MR.

4. Phenylmethyldiacetoxysilane

[00106] 5.00g (27.4mmol) of Phenylmethyldimethoxysilane, 7.00g (68.6mmol) of Acetic Anhydride and 2.40g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 120°C. Reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (lh at 80→120°C, P 60mm Hg), giving 4.70g (72%) of V - uncolored transparent liquid stored in refrigerator. Its structure is confirmed by FTIR and 1H NMR.

5. «-Octadecylmethyldiacetoxysilane

[00107] 5.00g (13.9mmol) of «-Octadecylmethyldimetoxysilane, 3.56g (34.9mmol) of Acetic Anhydride and 1.71g (20% of reagent's mixture) of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for lh at 130°C. Warm reaction mixture is decanted from Dowex resin, and subjected to vacuum distillation of the side products (lh at 50→105°C, P 50mm Hg), giving 4.24g (70%) of off-white solid. Its structure is confirmed by FTIR and 1H NMR.

6. «-Octyltriacetoxysilane

[00108] 5.00g (21.3mmol) of «-Octyltrimethoxysilane, 8.17g (80.0mmol) of Acetic Anhydride and 2.63g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 6h at 125-130°C. Reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (lh at 80→90°C, P 45mm Hg), giving 6.06g (89%) of light beige transparent liquid. Its structure is confirmed by FTIR and 1H NMR. 7. «-Octadecyltriacetoxysilane

[00109] 5.00g (13.3mmol) of «-Octadecyltrimethoxysilane, 5.1 lg (50.0mmol) of Acetic Anhydride and 2.00g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 6h at 130°C. Warm reaction mixture is decanted from Dowex resin, and subjected to vacuum distillation of the side products (lh at 50→100°C, P 45mm Hg), giving 3.60g (59%) of an off-white solid. Its structure is confirmed by FTIR and 1H MR.

8. 4-Phenylbutyltriacetoxysilane

[00110] 5.00g (19.6mmol) of «-Phenylbutyltrimethoxysilane, 8.17g (88.4mmol) of Acetic Anhydride and 2.90g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred for 2h gradually increasing temperature from 115 to 200°C. Cooled reaction mixture is filtered from Dowex resin, giving 4.14g (62%) of a light beige transparent viscous liquid stored in refrigerator. Its structure is confirmed by FTIR and 1H NMR.

[00111] 20.00g (78.6mmol) of 4-Phenylbutyltrimethoxysilane, 36.1 lg (353.8mmol) of Acetic Anhydride and 11.22g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 200mL flask connected with direct condenser, and well stirred under N2 blanket for 2.5h at 135°C. Cooled reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (55min at 40→82°C, P 0.2-0.4 mm Hg giving 21.86g (82%) of a light beige transparent viscous liquid stored in refrigerator. Its structure is confirmed by FTIR, 1H and ²⁹ Si NMR.

9. 2-Phenylethyltriacetoxysilane

[00112] lO.OOg (44.2mmol) of 4-Phenylethyltrimethoxysilane, 20.30g (198.8mmol) of Acetic Anhydride and 6.06g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 100 mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 135°C. Cooled reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (35min at 40→90°C, P 0.2mm Hg giving 11.17g (81%)) of a light beige transparent viscous liquid stored in refrigerator. Its structure is confirmed by FTIR, 1H and ²⁹ Si NMR. 10. Divinyldiacetoxysilane

[00113] 5.00g (32.7mmol) of Divinyldichlorosilane and 8.33g (81,7mmol) of Acetic Anhydride are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 2.5h at 110°C.Then reaction mixture is subjected to vacuum distillation of the side products (lh at 80→110°C, P 55 (mm Hg), giving 5.83g (89%) of a light yellow transparent liquid. Its structure is confirmed by FTIR and 1H MR.

11. «-Octylmethyldiacetoxysilane

[00114] 5.00g (22.9mmol) of n-Octylmethyldimethoxysilane and 5.84g (57.2mmol) of Acetic Anhydride and 2.17g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 125°C. Cooled reaction mixture is filtered from Dowex resin and subjected to vacuum distillation of the side products (lh at 40→115°C, P 55mm Hg), giving 5.74g (91%) of a light yellow transparent liquid. Its structure is confirmed by FTIR and 1H NMR.

12. 4-Phenylbutyldimethylacetoxysilane

[00115] 5.00g (22.04mmol) of 4-Phenylbutyldimethylchlorosilane and 2.70g (26.5mmol) of Acetic Anhydride are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 9h at 100— >150°C. Then reaction mixture is subjected to vacuum distillation of the side products (25min at 65→140°C, P 55mm Hg), giving 3.99g (72%) of a light yellow transparent liquid. Its structure is confirmed by FTIR, 1H and ²⁹ Si NMR.

13. Bis(triacetoxysilyl)methane

[00116] 5.00g (14.7mmol) of Bis(trimethoxysilyl)methane , 13.49g (132. lmmol) of Acetic Anhydride and 3.70g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 135°C. Cooled reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (30min at 50→130°C, P 60mm Hg giving 4.32g (69%) of a light brown transparent viscous liquid stored in refrigerator. Its structure is confirmed by FTIR, 1H and ²⁹ Si NMR. 14. 4-Phenylbutyltributyroxysilane

[00117] lO.OOg (39.3mmol) of 4-Phenylbutyltrimethoxysilane, 27.98g (176.9mmol) of Acetic Anhydride and 7.60g of "Dowex Monosphere 650C UPW" acid resin (dried at 120°C) are mixed in 50mL flask connected with direct condenser, and well stirred under N2 blanket for 3h at 135-140°C. Cooled reaction mixture is filtered from Dowex resin, and subjected to vacuum distillation of the side products (50min at 40→80°C, P 0.2mm Hg) giving 12.39g (75%) of a light beige transparent viscous liquid stored in refrigerator. Its structure is confirmed by FTIR, 1H and ²⁹ Si NMR.

[00118] Other triacetoxysilanes, including Butyl-, Butenyl-, 7-Octenyl-, Iso-Octyl-, 4-Phenylethyl- , Phenyl-, 2-(Diphenylphosphino)ethyl-, Naphthyl-, Naphthylmethyl- , and (9)-Anthracenyl- were prepared via similar procedures, with atm. distillation up to 170-200C.

II. CORNER CAPPED HEPTAPHENYL POSS MATERIALS, T8Ph ₇ R

15. HeptaphenylAminopropyl POSS (l-(3-aminopropyl)-3,5,7,9,l 1, 13,15- phenylpentacyclo-[9.5.1.13,9.15,15.17,13 ]octasiloxane)

[00119] To a stirred mixture of 5.00g (5.37mmol) of TriSilanolPhenyl POSS and 8mL of Toluene (cooled to -57°C) 1.21g (6.76mmol) of aminopropyltrimethoxysilane is added in lmin, reaction mixture is let to warm to RT, and is stirred overnight, solid precipitate is filtered, mixed with 5mL Ethanol, vigorously stirred for lOmin, filtered and dried at RT in vacuum, P 50mm Hg, giving 2.50g (46%) of white powder. Its structure is confirmed by 1H and ²⁹ Si NMR.

16. HeptaphenylPhenylbutyl POSS (l-(4-phenylbutyl)-3,5,7,9, l 1,13, 15-phenylpentacyclo- [9.5.1.13,9.15, 15.17, 13]octasiloxane)

[00120] To a solution of 4.00g (4.30mmol) of TriSilanolPhenyl POSS and 1.207g

(4.51mmol) Phenylbutyltrichlorosilane in 50mL THF, a THF (lOmL) solution of 1.434g Triethylamine is added dropwise for 20min, reaction mixture is stirred overnight,

triethylammonium hydrochloride is filtered out, and filtrate vac. evaporated to dryness. The solid was extracted by 44mL of Diethyl Ether, undissolved solid filtered out and dried at RT giving 2.1 lg (45%) of white powder. Its structure is confirmed by 1H and ²⁹ Si NMR. [00121] Other Corner Capped POSS materials were prepared via similar procedures:

Hepta-iso-butylPhenylbutyl POSS, HeptaphenylChloromethyl POSS, Hepta-iso- butylChloromethyl POSS.

17. POSS from TetrasilanolPhenylPOSS and Divinyldichlorosilane

[00122] To a solution of 5.00g (4.68mmol) of TetrasilanolPhenyl POSS and 1.750g (11.4mmol) Divinyldichlorosilane (90%-th) in 75mL THF, a solution of 2.08g Triethylamine (20.6mmol) in 8mL of THF is added dropwise for 20min, reaction mixture is stirred overnight, Triethylammonium hydrochloride is filtered out, and filtrate vac. evaporated to dryness. The solid (5.4g) was extracted by 30mL of Diethyl Ether, undissolved solid filtered out and dried at RT giving 3.22g (56%) of white powder. Its structure is confirmed by 1H and ²⁹ Si NMR.

18. POSS from TetrasilanolPhenylPOSS and Vinyltrichlorosilane

[00123] To a solution of lO.OOg (9.35mmol) of TetrasilanolPhenyl POSS and 3.17g (19.6mmol) Vinyltrichlorosilane in 150mL THF, a solution of 4.16g Triethylamine

(41.1mmol) in lOmL of THF is added dropwise for 20min, reaction mixture is stirred overnight, Triethylammonium hydrochloride is filtered out, and filtrate vac. evaporated to dryness, giving 11.3g (97%) of the product. Its structure is confirmed by 1H and ²⁹ Si NMR.

19. CL2Si<02Si[T8Ph8]02>SiCL2

[00124] To a solution of 20.00g (18.7mmol) of TetrasilanolPhenyl POSS and 6.99g (41.1mmol) Tetrachlorosilane in 312mL THF, a solution of 8.33g Triethylamine (82.3mmol) in 8mL of THF is added dropwise for 20min, reaction mixture is stirred overnight,

Triethylammonium hydrochloride is filtered out, and filtrate vac. evaporated to dryness giving 23.34g (99%) of the product. Its structure is confirmed by 1H and ²⁹ Si NMR.

20. (BuO)2Si<02Si[T8Ph8]02>Si(OBu)2

[00125] To a solution of 5.00g (3.96mmol) of CL2Si<02Si[T8Ph8]02>SiCL2 (item 19) and 1.29g (17.4mmol) n-Butanol in 25mL THF, a solution of 1.76g Triethylamine

(17.4mmol) in 4mL of THF is added dropwise for 15min, reaction mixture is stirred overnight, Triethylammonium hydrochloride is filtered out, and filtrate vac. evaporated to dryness giving 4.97g (89%) of the product. Its structure is confirmed by 1H and ²⁹ Si NMR. 21. (OctO)2Si<02Si[T8Ph8]02>Si(OOct)2

[00126] (OctO)2Si<02Si[T8Ph8]02>Si(OOct)2 (yield 94%) was obtained similarly to item 20.

22. T8/-Bu802>Si(OEt)2

[00127] To a solution of 5.00g (5.61mmol) of Disilanolisobutyl POSS and 1.25g

(12.3mmol) of Triethylamine in 38mL THF, a solution of 1.24g Diethoxydichlorosilane (6.54mmol) in 6mL of THF is added dropwise for 6min at 24-28°C, reaction mixture is stirred overnight, Triethylammonium hydrochloride is filtered out, and filtrate vac.

evaporated to dryness giving 4.96g (88%) of the product. Its structure is confirmed by 1H and ²⁹ Si MR.

EXAMPLE 3

[00128] Films were prepared from phenylbutyltriacetoxysilane 1% in n-butylacetate and subjected to stress testing as follows:

1. Spin coat 1,500 rpm

2. Hot plate # 1 150 °C 2 minutes

3. Hotplate # 2 300 or 350 °C 2 minutes

4. Stress Test 400 °C 30 minutes

[00129] 1 ml of liquid was dispensed on to a lxl" Si coupon and spun at 1500 rpm for 90 seconds. The coupon was transferred to a hot-plate and heated in air at 150°C for 2 minutes. The coupon was then transferred to a second hot-plate and heated under nitrogen for 2 minutes. The stress test was performed in a furnace under nitrogen for 30 minutes. Film thickness, refractive index, were measured by ellipsometry. K value was measured using a mercury probe. Modulus and hardness were measure by nanoindentation. Ellipsometric Porosimetry (EP) was used to measure porosity.

[00130] Results of testing are shown in Fig. 6, Table 2.

EXAMPLE 4

[00131] Films were prepared from phenylbutyltriacetoxysilane 1% in n-butylacetate and subjected to stress testing as follows: 1. Spin coat 1,500 rpm

2. Hot plate # 1 : 150 °C 2 minutes

3. Heat Treatment # 2: 400 °C for 10 minutes; 300 °C for 1 minute or 300 °C for 2 minutes

4. Stress Test 400 °C 30 minutes

[00132] 1 ml of liquid was dispensed on to a lxl" Si coupon and spun at 1500 rpm for 90 seconds. The coupon was transferred to a hot-plate and heated in air at 150°C for 2 minutes. The coupon was then transferred to a second hot-plate and heated under nitrogen for 2 minutes. The stress test was performed in a furnace under nitrogen for 30 minutes. Film thickness, refractive index, were measured by ellipsometry. K value was measured using a mercury probe. Modulus and hardness were measure by nanoindentation. Ellipsometric Porosimetry (EP) was used to measure porosity

[00133] Results of testing are shown in Fig. 7, Table 3.

[00134] Although the present invention has been described in connection with the preferred embodiments, it is to be understood that modifications and variations may be utilized without departing from the principles and scope of the invention, as those skilled in the art will readily understand. Accordingly, such modifications may be practiced within the scope of the invention and the following claims.