Additives to enhance the properties of dielectric films

Abstract

A method for improving the elastic modulus of dense organosilica dielectric films (k2.7) without negatively impacting the film's electrical properties and with minimal to no reduction in the carbon content of the film. The method comprising the steps of: providing a substrate within a reaction chamber; introducing into the reaction chamber a gaseous composition comprising a mixture of an alkyl-alkoxysilacyclic compound and 5% or less of certain bis(alkoxy)silanes or mono-alkoxysilanes; and applying energy to the gaseous composition comprising the mixture of the alkyl-alkoxysilacyclic compound and 5% or less of certain bis(alkoxy)silanes or mono-alkoxysilanes to deposit an organosilicon film on the substrate, wherein the organosilicon film has a dielectric constant from 2.70 to 3.30, an elastic modulus of from 6 to 30 GPa, and an at. % carbon from 10 to 45 as measured by XPS.

Claims

1. A method for making a dense organosilica film, the method comprising: providing a substrate within a reaction chamber; introducing into the reaction chamber a gaseous mixture comprising reagent a) an alkyl-alkoxysilacyclic compound of Formula (1) ##STR00002## wherein R.sup.1 is independently selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group; R.sup.2 is selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group; and R.sup.3 is selected from a C.sub.3 to C.sub.10 alkyl di-radical which forms a four-membered, five-membered, or six-membered cyclic ring with the Si atom, and reagent b) a bis-alkoxysilane having the structure given in Formula (2) or a mono-alkoxysilane having the structure given in Formula (3):
R.sup.6R.sup.5Si(OR.sup.4).sub.2(2)
HR.sup.6R.sup.5Si(OR.sup.4)(3) wherein R.sup.4 is selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group and R.sup.5 and R.sup.6 are independently selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group; applying energy to the gaseous mixture in the reaction chamber to induce reaction of the gaseous mixture and to thereby deposit the dense organosilica film on the substrate, wherein the mixture is introduced into the reaction chamber with flow rates for reagents a and b ranging between 5 and 5000 sccm, and with reagent b being no more than 5% of the mixture.

2. The method of claim 1, wherein the alkyl-alkoxysilacyclic compound of Formula (1) is substantially free of one or more impurities selected from the group consisting of a halide, water, metals, and combinations thereof.

3. The method of claim 1, wherein the bis-alkoxysilane having the structure given in Formula (2) is substantially free of one or more impurities selected from the group consisting of a halide, water, metals, and combinations thereof.

4. The method of claim 1, wherein the mono-alkoxysilane having the structure given in Formula (3) is substantially free of one or more impurities selected from the group consisting of a halide, water, metals, and combinations thereof.

5. The method of claim 1, wherein the organosilica film has a dielectric constant of from 2.70 to 3.30, an elastic modulus of from 6 to 30 GPa, and an XPS carbon content of 10 to 45%.

6. The method of claim 1 which is a chemical vapor deposition method.

7. The method of claim 1 which is a plasma enhanced chemical vapor deposition method.

8. The method of claim 1 wherein the gaseous composition further comprises at least one oxidant selected from the group consisting of O.sub.2, N.sub.2O, NO, NO.sub.2, CO.sub.2, CO, water, H.sub.2O.sub.2, ozone, alcohols, and combinations thereof.

9. The method of claim 1 wherein the gaseous composition does not comprise an oxidant.

10. The method of claim 1 wherein the reaction chamber in the applying step comprises at least one gas selected from the group consisting of He, Ar, N.sub.2, Kr, Xe, CO.sub.2, and CO.

11. The method of claim 1 wherein the organosilica film has a refractive index (RI) of from 1.3 to 1.7 at 632 nm.

12. The method of claim 1 wherein the organosilica film is deposited at a rate of from 5 nm/min to 600 nm/min.

13. A gaseous composition comprising reagent a) an alkyl-alkoxysilacyclic compound of Formula (1) ##STR00003## wherein R.sup.1 is independently selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group; R.sup.2 is selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group; and R.sup.3 is selected from a C.sub.3 to C.sub.10 alkyl di-radical which forms a four-membered, five-membered, or six-membered cyclic ring with the Si atom; and reagent b) a bis-alkoxysilane having the structure given in Formula (2) or a mono-alkoxysilane having the structure given in Formula (3):
R.sup.6R.sup.5Si(OR.sup.4).sub.2(2)
HR.sup.6R.sup.5Si(OR.sup.4)(3) wherein R.sup.4 is selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group and R.sup.5 and R.sup.6 are independently selected from hydrogen, a linear or branched C.sub.1 to C.sub.10 alkyl group, a linear or branched C.sub.2 to C.sub.10 alkenyl group, a linear or branched C.sub.2 to C.sub.10 alkynyl group, a C.sub.3 to C.sub.10 cyclic alkyl group, a C.sub.3 to C.sub.10 hetero-cyclic alkyl group, a C.sub.5 to C.sub.10 aryl group, and a C.sub.3 to C.sub.10 hetero-aryl group, wherein the mixture has no greater than 5% of reagent b.

14. The composition of claim 1, wherein the alkyl-alkoxysilacyclic compound of Formula (1) is substantially free of chloride ions.

15. The composition of claim 14, wherein chloride ions, if present, are present at a concentration of 50 ppm or less as measured by IC.

16. The composition of claim 15, wherein the chloride ions, if present, are present at a concentration of 10 ppm or less as measured by IC.

17. The composition of claim 16, wherein the chloride ions, if present, are present at a concentration of 5 ppm or less as measured by IC.

18. The composition of claim 13, the wherein the bis-alkoxysilane having the structure given in Formula (2) is substantially free of chloride ions.

19. The composition of claim 18, wherein the chloride ions, if present, are present at a concentration of 10 ppm or less as measured by IC.

20. The composition of claim 19, wherein the chloride ions, if present, are present at a concentration of 5 ppm or less as measured by IC.

21. The composition of claim 13, the wherein the mono-alkoxysilane having the structure given in Formula (3) is substantially free of chloride ions.

22. The composition of claim 21, wherein chloride ions, if present, are present at a concentration of 50 ppm or less as measured by IC.

23. The composition of claim 22, wherein the chloride ions, if present, are present at a concentration of 10 ppm or less as measured by IC.

24. The composition of claim 23, wherein the chloride ions, if present, are present at a concentration of 5 ppm or less as measured by IC.

Description

BRIEF SUMMARY OF THE DRAWINGS

(1) FIG. 1 shows the infrared spectrum of a comparative film deposited from 1-methyl-1-ethoxy-1-silacyclopentane (MPSCP) and a spectrum of a film deposited from a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane.

(2) FIG. 2 shows the leakage current density as a function of applied electric field for three different low k films: a comparative film deposited from DEMS, a comparative film deposited from a mixture of DEMS and TEOS, and a film deposited from a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane.

DETAILED DESCRIPTION OF THE INVENTION

(3) Described herein is a chemical vapor deposition method for making a dense organosilica film with improved mechanical properties, the method comprising the steps of: providing a substrate within a reaction chamber; introducing into the reaction chamber a gaseous mixture comprising an alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3), a gaseous oxidant such as O.sub.2 or N.sub.2O, and an inert gas such as He; and applying energy to the gaseous mixture comprising an alkyl-alkoxysilacyclic compound of Formula (1) and a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3) in the reaction chamber to induce reaction of the gaseous mixture comprising an alkyl-alkoxysilacyclic compound of Formula (1) and a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3) to deposit an organosilica film on the substrate, wherein the organosilica film has a dielectric constant of from 2.70 to 3.30, an elastic modulus from 6 to 30 GPa, and an atomic % carbon from 10 to 45 as measured by XPS, preferably a dielectric constant of from 2.80 to 3.20, an elastic modulus of from 7 to 27 GPa, and an atomic % carbon from 10 to 40 as measured by XPS. It is recognized that OSG films with the desired film properties can also be deposited using a gaseous composition that does not include an oxidant.

(4) The gaseous mixture comprising an alkyl-alkoxysilacyclic compound of Formula (1), such as 1-methyl-1-ethoxy-1-silacyclopentane (MPSCP), and 5% or less a bis-alkoxysilane compound having the structure given in Formula (2), such as bis(isopropoxy)-methyl-butylsilane, or a mono-alkoxysilane compound having the structure given in Formula (3), such as dimethyl-isopropoxysilane, provides unique attributes that make it possible to achieve a relatively low dielectric constant for a dense organosilica film with a higher elastic modulus compared to films deposited from an alkyl-alkoxysilacyclic compound in the absence of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3). While the addition of 5% or less of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3) to an alkyl-alkoxysilacyclic compound of Formula (1) increases the elastic modulus of the as deposited film, it has minimal to no change on the dielectric constant of the film, minimal to no change on the XPS carbon content of the film, is expected to result in minimal to no change in the films resistance to PID, and is expected to result in minimal to no change in the leakage current or initial breakdown field of the film relative to the equivalent film deposited in the absence of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3). The increase in the elastic modulus occurs for the as deposited film, that is without a post-deposition treatment such as a UV cure.

(5) It is unexpected that the addition of 5% or less of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3) to an alkyl-alkoxysilacyclic based deposition of Formula (1) would result in an increase in the elastic modulus without resulting in an increase in the dielectric constant, a lower XPS carbon content, an expected decrease in resistance to PID, an expected increase in leakage current, and an expected decrease in the initial breakdown field. To illustrate, the examples in U.S. Pat. No. 8,137,764 show that to achieve a measurable increase in the film's mechanical properties relative to a DEMS only based deposition a high percentage of hardening additive is required, between 25% to 75%. Further, as the percentage of hardening additive is increased the mechanical properties of the resulting film increase. As the hardening additive in U.S. Pat. No. 8,137,764 contains 3 to 4 silicon oxygen bonds per silicon atom and no silicon-carbon bonds (such as TEOS or triethoxysilane (TES)), it is dilutive to the carbon content of the low k film, resulting in a lower XPS carbon content and less resistance to PID. Thus, as the percentage of hardening additive is increased the mechanical properties of the film increase, the carbon content of the film decreases, and the oxygen content of the film increases. Similarly, the examples in U.S. Pat. Appl. No. 2019/0244810 show that to achieve a measurable increase in the film's mechanical properties relative to a DEMS based deposition a high percentage of hardening additive (isobutyl-triethoxysilane, iBTEOS) is required; between 66% to 80%. The triethoxysilane based hardening additive iBTEOS in U.S. Pat. Appl. No. 2019/0244810 has one silicon-carbon bond and three silicon-alkoxy groups per silicon and is thus dilutive to the carbon content of the film relative to contributions from the DEMS precursor, which has only two silicon-alkoxy groups per silicon. This is reflected in the low XPS carbon content (<11%) of all example films in U.S. Pat. Appl. No. 2019/0244810. The increased mechanical properties of the example films in U.S. Pat. No. 8,137,764 and U.S. Pat. Appl. No. 2019/0244810 is thus attributed to a higher oxygen content and a lower carbon content relative to DEMS based films deposited in the absence of a hardening additive at the same value of the dielectric constant. The increased oxygen content likely results in better three-dimensional network connectivity, and thus the improved mechanical properties. However, the lower carbon content in the example films in U.S. Pat. No. 8,137,764 and U.S. Pat. Appl. No. 2019/0244810 is expected to result in a decreased resistance to PID. It is thus unexpected that the addition of 5% or less of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3) to a mono-alkoxy alkyl-alkoxysilacyclic based deposition would result in an increase in the elastic modulus of the film with minimal to no increase in the dielectric constant, minimal to no increase in the XPS carbon content, minimal to no decrease in the resistance to PID, minimal to no increase in the leakage current, and minimal to no decrease in the initial breakdown field.

(6) Dense low k films deposited in accordance with U.S. Pat. No. 8,137,764 exhibit a higher leakage current and a lower initial breakdown field relative to films deposited in the absence of a hardening additive. That is films deposited using a mixture of a hardening additive containing no silicon carbon bonds (e.g., TEOS) and a low k precursor containing one or more silicon-carbon bonds (e.g., DEMS) have a higher leakage current and a lower initial breakdown field relative to DEMS based films deposited without a hardening additive. This is clearly not desirable as IC manufacturers are continually driving to decrease the leakage current and increase the initial breakdown field as device geometries continue to shrink, particularly for the lowest levels in the BEOL. In contrast, dense low k films deposited from a gaseous mixture comprising an alkyl-alkoxysilacyclic compound of Formula (1) such as MPSCP and 5% or less of a bis-alkoxysilane compound having the structure given in Formula (2), such as bis(isopropoxy)-methyl-butylsilane, or a mono-alkoxysilane compound having the structure given in Formula (3), such as dimethyl-isopropoxysilane, in accordance with this invention are expected to show minimal to no change in the leakage current and initial breakdown field relative to a film deposited from an alkyl-alkoxysilacyclic compound of Formula (1) in the absence of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3).

(7) Some of advantages over the prior art alkyl-alkoxysilacyclic based films achieved with this invention include, but are not limited to: an increase the elastic modulus of the film with minimal to no change in the dielectric constant of the film, minimal to no change in the XPS carbon content of the film, expected minimal to no reduction in the films resistance to PID, and expected minimal to no increase in the leakage current, and expected minimal to no decrease in the initial breakdown field of the film relative to an equivalent film deposited in the absence of a bis-alkoxysilane compound having the structure given in Formula (2) or a mono-alkoxysilane compound having the structure given in Formula (3).

(8) The alkyl-alkoxysilacyclic compounds of Formula (1), the bis-alkoxysilane compounds of Formula (2), and the mono-alkoxysilane compound of Formula (3) are preferably substantially free of halide ions. As used herein, the term substantially free as it relates to halide ions (or halides) such as, for example, chlorides (i.e. chloride-containing species such as HCl or silicon compounds having at least one SiCl bond) and fluorides, bromides, and iodides, means less than 5 ppm (by weight) measured by ion chromatography (IC), preferably less than 3 ppm measured by IC, and more preferably less than 1 ppm measured by IC, and most preferably 0 ppm measured by IC. Significant levels of chloride in the final product can cause the silicon precursor compounds to degrade. The gradual degradation of the silicon precursor compounds may directly impact the film deposition process making it difficult for the semiconductor manufacturer to meet film specifications. In addition, the shelf-life or stability is negatively impacted by the higher degradation rate of the silicon precursor compounds thereby making it difficult to guarantee a 1-2 year shelf-life. Therefore, the accelerated decomposition of the silicon precursor compounds presents safety and performance concerns related to the formation of these flammable and/or pyrophoric gaseous byproducts. The alkyl-alkoxysilacyclic compounds of Formula (1), the bis-alkoxysilane compounds of Formula (2), and the mono-alkoxysilane compound of Formula (3) are preferably substantially free of metal ions such as, Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, Ca.sup.2+, Al.sup.3+, Fe.sup.2+, Fe.sup.3+, Ni.sup.2+, Cr.sup.3+. As used herein, the term substantially free as it relates to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr means less than 5 ppm (by weight), preferably less than 3 ppm, and more preferably less than 1 ppm, and most preferably 0.1 ppm as measured by ICP-MS. In some embodiments, the alkyl-alkoxysilacyclic compounds of Formula (1), the bis-alkoxysilane compounds of Formula (2), and the mono-alkoxysilane compound of Formula (3) are free of metal ions such as, Li.sup.+, Na.sup.+, K.sup.+, Mg.sup.2+, Ca.sup.2+, Al.sup.3+, Fe.sup.2+, Fe.sup.3+, Ni.sup.2+, Cr.sup.3+. As used herein, the term free of metal impurities as it relates to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr, means less than 1 ppm, preferably 0.1 ppm (by weight) as measured by ICP-MS, most preferably 0.05 ppm (by weight) as measured by ICP-MS or other analytical method for measuring metals.

(9) The low k dielectric films are organosilica glass (OSG) films or materials. Organosilicates are employed in the electronics industry, for example, as low k materials. Material properties depend upon the chemical composition and structure of the film. Since the composition of the gaseous mixture of organosilicon precursors has a strong effect upon the films structure and composition, it is beneficial to use a mixture of organosilicon precursors that provide the required film properties to ensure that the addition of the needed amount of porosity to reach the desired dielectric constant does not produce films that are mechanically unsound. The method and composition described herein provide the means to generate low k dielectric films that have a desirable balance of electrical and mechanical properties as well as other beneficial film properties as high carbon content to provide improved integration plasma resistance.

(10) In certain embodiments of the method and composition described herein, a layer of silicon-containing dielectric material is deposited on at least a portion of a substrate via a chemical vapor deposition (CVD) process employing a reaction chamber. The method thus includes the step of providing a substrate within a reaction chamber. Suitable substrates include, but are not limited to, semiconductor materials such as gallium arsenide (GaAs), silicon, and compositions containing silicon such as crystalline silicon, polysilicon, amorphous silicon, epitaxial silicon, silicon dioxide (SiO.sub.2), silicon glass, silicon nitride, fused silica, glass, quartz, borosilicate glass, and combinations thereof. Other suitable materials include chromium, molybdenum, and other metals commonly employed in semi-conductor, integrated circuits, flat panel display, and flexible display applications. The substrate may have additional layers such as, for example, silicon, SiO.sub.2, organosilicate glass (OSG), fluorinated silicate glass (FSG), boron carbonitride, silicon carbide, hydrogenated silicon carbide, silicon nitride, hydrogenated silicon nitride, silicon carbonitride, hydrogenated silicon carbonitride, boronitride, organic-inorganic composite materials, photoresists, organic polymers, porous organic and inorganic materials and composites, metal oxides such as aluminum oxide, and germanium oxide. Still further layers can also be germanosilicates, aluminosilicates, copper and aluminum, and diffusion barrier materials such as, but not limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, or WN.

(11) The reaction chamber is typically, for example, a thermal CVD or a plasma enhanced CVD reactor or a batch furnace type reactor in a variety of ways. In one embodiment, a liquid delivery system may be utilized. In liquid delivery formulations, the precursor mixture comprised of an alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane Formula (2) or a mono-alkoxysilane compound of Formula (3) may be delivered in neat liquid form, or alternatively, may be employed in solvent formulations or compositions comprising same. Thus, in certain embodiments the precursor formulations may include solvent component(s) of suitable character as may be desirable and advantageous in a given end use application to form a film on a substrate.

(12) The method disclosed herein includes the step of introducing into the reaction chamber a gaseous composition comprising an alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane of Formula (2) or a mono-alkoxysilane compound of Formula (3). In some embodiments, the composition may include additional reactants such as, for example, oxygen-containing species such as, for example, O.sub.2, O.sub.3, and N.sub.2O, gaseous or liquid organic substances, alcohols, CO.sub.2, or CO. In one embodiment, the reaction mixture introduced into the reaction chamber comprises at least one oxidant selected from the group consisting of O.sub.2, N.sub.2O, NO, NO.sub.2, CO.sub.2, water, H.sub.2O.sub.2, ozone, and combinations thereof. In an alternative embodiment, the reaction mixture does not comprise an oxidant.

(13) The composition for depositing the dielectric film described herein comprises from about 95 to about 99.9 weight percent of an alkyl-alkoxysilacyclic compound of Formula (1)

(14) The composition for depositing the dielectric film described herein comprises from about 5 to about 0.1 weight percent of a bis-alkoxysilane of Formula (2).

(15) The composition for depositing the dielectric film described herein comprises from about 5 to about 0.1 weight percent of a mono-alkoxysilane compound of Formula (3).

(16) In embodiments, the gaseous composition comprising the alkyl-alkoxysilacyclic compound of Formula (1) is substantially free of or free of halides such as, for example, chlorides.

(17) In embodiments, the gaseous composition comprising the bis-alkoxysilane compound of Formula (2) is substantially free of or free of halides such as, for example, chlorides.

(18) In embodiments, the gaseous composition comprising the mono-alkoxysilane compound of Formula (3) is substantially free of or free of halides such as, for example, chlorides.

(19) In addition to the gaseous composition comprising an alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3), additional materials can be introduced into the reaction chamber prior to, during and/or after the deposition reaction. Such materials include, e.g., inert gas (e.g., He, Ar, N.sub.2, Kr, Xe, etc., which may be employed as a carrier gas for lesser volatile precursors and/or which can promote the curing of the as-deposited materials and potentially provide a more stable final film if desired). Excited states of the inert gas generated during the plasma based deposition process can also play an important role during the deposition process.

(20) Any reagent employed, including the alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3) can be carried into the reactor separately as distinct sources or as a mixture. The reagents can be delivered to the reactor system by any number of means, preferably using a pressurizable stainless steel vessel fitted with the proper valves and fittings to allow the delivery of liquid to the process reactor. Preferably, the precursor is delivered into the process vacuum chamber as a gas, that is, the liquid must be vaporized before it is delivered into the process chamber. Carrier gases such as N.sub.2, He, or Ar may be used to help vaporize and transport vapors into the reactor.

(21) The method disclosed herein includes the step of applying energy to the gaseous composition comprising the alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3) in the reaction chamber to induce reaction of the gaseous composition comprising the alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3) to deposit an organosilica film on the substrate, wherein the organosilica film has a dielectric constant of from 2.70 to 3.30 in some embodiments, 2.70 to 3.20 in other embodiments, and 2.80 to 3.10 in still preferred embodiments, an elastic modulus of from 6 to 30 GPa, and an at. % carbon of from 10 to 45 as measured by XPS. Energy is applied to the gaseous reagents to induce the alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3) and other reactants, if present, to react and to form the film on the substrate. Such energy can be provided by, e.g., plasma, pulsed plasma, helicon plasma, high density plasma, inductively coupled plasma, remote plasma, hot filament, and thermal (i.e., non-filament) and methods. A secondary RF frequency source can be used to modify the plasma characteristics at the substrate surface. Preferably, the film is formed by plasma enhanced chemical vapor deposition (PECVD).

(22) The flow rate for each of the gaseous reagents preferably ranges from 5 to 5000 sccm, more preferably from 10 to 3000 sccm, per single 300 mm wafer. The actual flow rates needed may depend upon wafer size and chamber configuration, and are in no way limited to 300 mm wafers or single wafer chambers.

(23) In certain embodiments, the film is deposited at a deposition rate of from about 5 to 600 nanometers (nm) per minute. In other embodiments, the film is deposited at a deposition rate of from about 20 to 200 nanometers (nm) per minute.

(24) The pressure in the reaction chamber during deposition typically ranges from about 0.01 to about 600 torr or from about 1 to 15 torr.

(25) The film is preferably deposited to a thickness of 0.001 to 500 microns, although the thickness can be varied as required. The blanket film deposited on a non-patterned surface has excellent uniformity, with a variation in thickness of less than 3% over 1 standard deviation across the substrate with a reasonable edge exclusion, wherein e.g., a 5 mm outermost edge of the substrate is not included in the statistical calculation of uniformity.

(26) In addition to the inventive OSG products, the present invention includes the process by which the products are made, methods of using the products and compounds and compositions useful for preparing the products. For example, a process for making an integrated circuit on a semiconductor device is disclosed in U.S. Pat. No. 6,583,049, which is herein incorporated by reference.

(27) The dense organosilica films produced by the disclosed methods exhibit excellent resistance to plasma induced damage, particularly during etch and photoresist strip processes.

(28) The dense organosilica films produced by the disclosed methods exhibit excellent mechanical properties for a given dielectric constant relative to dense organosilica films having the same dielectric constant but made from an alkyl-alkoxysilacyclic compound of Formula (1) in the absence of 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3). The resulting organosilica film (as deposited) typically has a dielectric constant of from 2.70 to 3.30 in some embodiments, 2.80 to 3.20 in other embodiments, and 2.70 to 3.10 in still other embodiments, an elastic modulus of from 6 to 30 GPa, and an at. % carbon of from 10 to 45 as measured by XPS. In other embodiments, the resulting organosilica film has a dielectric constant of from 2.70 to 3.30 in some embodiments, 2.80 to 3.20 in other embodiments, and 2.80 to 3.10 in still other embodiments, an elastic modulus of from 6 to 30 GPa, and an at. % carbon of from 10 to 45 as measured by XPS.

(29) The resultant dense organosilica films may also be subjected to a post treating process once deposited. Thus, the term post-treating as used herein denotes treating the film with energy (e.g., thermal, plasma, photon, electron, microwave, etc.) or chemicals to further enhance materials properties.

(30) The conditions under which post-treating are conducted can vary greatly. For example, post-treating can be conducted under high pressure or under a vacuum ambient.

(31) UV annealing is a preferred method conducted under the following conditions.

(32) The environment can be inert (e.g., nitrogen, CO.sub.2, noble gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygen environments, enriched oxygen environments, ozone, nitrous oxide, etc.) or reducing (dilute or concentrated hydrogen, hydrocarbons (saturated, unsaturated, linear or branched, aromatics), etc.). The pressure is preferably about 1 Torr to about 1000 Torr. However, a vacuum ambient is preferred for thermal annealing as well as any other post-treating means. The temperature is preferably 200-500 C., and the temperature ramp rate is from 0.1 to 100 deg C./min. The total UV annealing time is preferably from 0.01 min to 12 hours.

(33) The invention will be illustrated in more detail with reference to the following examples, but it should be understood that it is not deemed to be limited thereto. It is also recognized that the precursors described in this invention can also be used to deposit porous low k films with similar process advantages relative to existing porous low k films (that is a higher elastic modulus for a given value of the dielectric constant with little to no change in the films XPS carbon content, and little to no change expected in the resistance to PID, leakage current, or breakdown field).

EXAMPLES

(34) All experiments were performed on a 300 mm AMAT Producer SE, which deposits films on two wafers at the same time. Thus, the precursor and gas flow rates correspond to the flow rates required to deposit films on two wafers at the same time. The stated RF power per wafer is correct, as each wafer processing station has its own independent RF power supply. The stated deposition pressure is correct, as both wafer processing stations are maintained at the same pressure.

(35) Although illustrated and described above with reference to certain specific embodiments and examples, the present invention is nevertheless not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention. It is expressly intended, for example, that all ranges broadly recited in this document include within their scope all narrower ranges which fall within the broader ranges. It is also recognized that the gaseous compositions comprising an alkyl-alkoxysilacyclic compound of Formula (1) and 5% or less of a bis-alkoxysilane compound of Formula (2) or a mono-alkoxysilane compound of Formula (3) disclosed in this invention can be used as the structure former for the deposition of porous low k films with a high elastic modulus for a given value of the dielectric constant with little to no change in the films XPS carbon content, and little to no change expected in the resistance to PID, leakage current, or breakdown field.

(36) Thickness and refractive index were measured on a Woollam model M2000 Spectroscopic Ellipsometer. Electrical properties of the films (i.e., dielectric constant, leakage current, initial breakdown field) were determined using Hg probe technique on mid-resistivity p-type wafers (range 8-12 ohm-cm). FTIR spectra were measured using a Thermo Fisher Scientific Model iS50 spectrometer fitted with a nitrogen purged Pike Technologies Map300 for handling 12-inch wafers. FTIR spectra were used to calculate the relative density of various functional groups in the film, such as the relative density of bridging disilylmethylene groups (via the SiCH.sub.2Si IR band centered near 1360 cm.sup.1), terminal silicon methyl groups (via the Si(CH.sub.3).sub.x IR bands centered near 1270 cm.sup.1), and CH.sub.x (via the CH.sub.x IR bands between 2800 cm.sup.1 and 3000 cm.sup.1). To illustrate, the relative density of bridging disilylmethylene groups in the film (i.e., the SiCH.sub.2Si density), as determined by infrared spectroscopy, was calculated as 1E4 times the area of the SiCH.sub.2Si infrared band centered near 1360 cm.sup.1 divided by the area of the SiO.sub.x bands between approximately 1250 cm.sup.1 to 920 cm.sup.1. Mechanical properties were determined using a KLA iNano Nanoindenter.

(37) Compositional data were obtained by x-ray photoelectron spectroscopy (XPS) on either a PHI 5600 (73560, 73808) or a Thermo K-Alpha (73846) and are provided in atomic weight percent. The atomic weight percent (%) values reported in the table do not include hydrogen.

Comparative Example 1: Deposition of a Dense Low k Film Using the 1-Methyl-1-Isopropoxy-1-Silacyclopentane (MPSCP) Precursor

(38) A dense MPSCP based film was deposited using the following process conditions for 300 mm processing. The MPSCP precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 2000 mg/min using 1500 standard cubic centimeters per minute (sccm) of He carrier gas flow, oxygen was delivered to the reaction chamber via a mass flow controller (MFC) at a flow rate of 25 sccm, 380 milli-inch showerhead/heated pedestal spacing, 400 C. pedestal temperature, 7.5 Torr chamber pressure to which a 391 Watt 13.56 MHz plasma was applied. Various attributes of the film (e.g., dielectric constant (k), elastic modulus and hardness, infrared spectra, and atomic weight percent carbon (% C)) were obtained as described above and are provided in Table 1.

(39) TABLE-US-00001 TABLE 1 Comparative properties for films deposited using 1-Methyl- 1-Isopropoxy-1-silacyclopentane (MPSCP) and a mixture of 1-Methyl-1-Isopropoxy-1-silacyclopentane (MPSCP) and 0.9% bis(isopropoxy)-methyl-butylsilane. MPSCP and 0.9% Bis(isopropoxy)-methyl- MPSCP Based Property butylsilane Based Film Film Dielectric Constant, k 3.1 3.1 Elastic Modulus (GPa) 19 18 RI (632 nm) 1.487 1.490 XPS Carbon Content (at. %) 30 30 CH.sub.x/SiO.sub.x*1E2 3.9 3.9 Si(CH.sub.3).sub.x/SiO.sub.x*1E2 2.4 2.4 SiCH.sub.2Si/SiO.sub.x*1E4 18 18

Comparative Example 2: Deposition of a Dense Low k Film Using a Mixture of 1-Methyl-1-Isopropoxy-1-Silacyclopentane (MPSCP) and 0.9% bis(isopropoxy)-methyl-butylsilane

(40) A dense low k film was deposited using a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane using the following process conditions for 300 mm processing. The mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 2000 mg/min using 1500 sccm of He carrier gas flow, oxygen was delivered to the reaction chamber via a MFC at a flow rate of 25 sccm, 380 milli-inch showerhead/heated pedestal spacing, 400 C. pedestal temperature, 7.5 Torr chamber pressure to which a 391 Watt 13.56 MHz plasma was applied. Various attributes of the film (e.g., dielectric constant (k), elastic modulus and hardness, infrared spectra, and atomic weight percent carbon (% C)) were obtained as described above and are provided in Table 1.

Example 3: Deposition of a Dense Low k Film Using the DEMS Precursor

(41) A dense DEMS based film was deposited using the following process conditions for 300 mm processing. The DEMS precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 750 mg/min using 2250 sccm of He carrier gas flow, 380 milli-inch showerhead/heated pedestal spacing, 345 C. pedestal temperature, 10 Torr chamber pressure to which a 200 Watt 13.56 MHz plasma was applied. Various attributes of the film (e.g., dielectric constant (k) and infrared spectra) were obtained as described above and are provided in Table 2.

(42) TABLE-US-00002 TABLE 2 Comparative properties for films deposited using DEMS and a 50:50 mixture of DEMS and TEOS. DEMS and TEOS Based DEMS Based Property Film Film Dielectric Constant, k 3.2 3.2 RI (632 nm) 1.402 1.461 CH.sub.x/SiO.sub.x*1E2 1.3 1.6 Si(CH.sub.3).sub.x/SiO.sub.x*1E2 2.1 2.1 SiCH.sub.2Si/SiO.sub.x*1E4 1.0 13

Example 4: Deposition of a Dense Low k Film Using a Mixture of DEMS and TEOS

(43) A dense low k film was deposited using a mixture of DEMS and TEOS using the following process conditions for 300 mm processing. The DEMS precursor was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1625 mg/min using 1000 sccm of He carrier gas flow, TEOS was delivered to the reaction chamber via direct liquid injection (DLI) at a flow rate of 1750 mg/min using 1000 sccm of He carrier gas flow, oxygen was delivered to the reaction chamber via a MFC at a flow rate of 50 sccm, 380 milli-inch showerhead/heated pedestal spacing, 300 C. pedestal temperature, 7.0 Torr chamber pressure to which a 400 Watt 13.56 MHz plasma was applied. Various attributes of the film (e.g., dielectric constant (k) and infrared spectra) were obtained as described above and are provided in Table 2.

(44) Table 1 shows that the film deposited using a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane has an unexpectedly high elastic modulus relative to the film deposited using MPSCP. Within the uncertainty of the measurement, both films have the same dielectric constant, the same XPS carbon content, the same relative CH.sub.x density, Si(CH.sub.3).sub.x density, and Si(CH.sub.2)Si density as calculated via their individual IR spectra. Thus, relative to the MPSCP based film, the film deposited using a mixture MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane has a higher elastic modulus (+5%) and exhibits little to no change in its other film properties. Consequently, the film deposited using a mixture MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane would be expected to have the same strong resistance to PID as the film deposited from MPSCP only. The film deposited using a mixture MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane would also be expected to have the same low leakage current and high initial breakdown field as the film deposited from MPSCP only.

(45) FIG. 1 shows the infrared spectrum of a comparative film deposited from MPSCP and a spectrum of a film deposited from a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane. The IR spectra are nearly identical and show that the film deposited using a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane exhibits little to no change in the identity and the relative density of the IR active functional groups relative to the film deposited only from MPSCP.

(46) FIG. 2 shows the current density as a function of the applied electric field for three different low k films: a comparative film deposited from DEMS, a comparative film deposited from a mixture of DEMS and TEOS, and a comparative film deposited from MPSCP. The film deposited from the mixture of DEMS and TEOS has a higher leakage current (typically the current density at an electric field strength of 1 MV/cm or 2 MV/cm) and a lower initial breakdown field (typically the strength of the electric field where the current density rapidly increases by at least two orders of magnitude) relative to the film deposited from DEMS. In contrast, the films described in this invention deposited from a mixture of MPSCP and 0.9% bis(isopropoxy)-methyl-butylsilane have a higher elastic modulus (+5%) and are expected to have a leakage current and initial breakdown field strength that is nearly identical to that of the film deposited from MPSCP only.

(47) The properties of the film deposited from DEMS and the film deposited from a mixture of DEMS and TEOS shown in FIG. 2 are given in Table 2. Both films have the same dielectric constant, but the film deposited from a mixture of DEMS and TEOS has less total carbon content as indicated by the smaller relative IR densities of CH.sub.x and SiCH.sub.2Si. Note that for the film deposited from a mixture of DEMS and TEOS the relative density of the bridging disilylmethylene (SiCH.sub.2Si) groups is lower by an order of magnitude relative to the film deposited from DEMS. Thus, the film deposited from a mixture of DEMS and TEOS is expected to have less resistance to PID than the film deposited from DEMS only.