Polyol-based precursors for producing nanoporous silica thin films

Claim 2

A nanoporous silica precursor composition which comprises at least one alkoxysilane; at least one relatively low volatility solvent composition comprising an ether of a C 1 to C 4 alkylene glycol which is miscible in water and alkoxysilanes, having a hydroxyl concentration of 0.021 mole/cm 3 or less, a boiling point of about 175° C. or more at atmospheric pressure and a weight average molecular weight of about 100 or more; at least one relatively high volatility solvent composition having a boiling point below that of the relatively low volatility solvent composition; optional water and an optional catalytic amount of an acid.

Claim 3

The composition of claim 1 which comprises water.

Claim 4

The composition of claim 1 which comprises a catalytic amount of an acid.

Claim 5

The composition of claim 1 which comprises both water and a catalytic amount of an acid.

Claim 6

The composition of claim 1 which is absent of water and absent of an acid catalyst.

Claim 7

The composition of claim 1 wherein the alkoxysilane comprises one or more components selected from the group consisting of alkoxysilanes having the formula: ##STR2## wherein at least 2 of the R groups are independently C 1 to C 4 alkQxy groups and the balance, if any, are independently selected from the group consisting of hydrogen, alkyl, phenyl, and halogen.

Claim 8

The composition of claim 6 wherein each R is methoxy, ethoxy or propoxy.

Claim 9

The composition of claim 1 wherein the alkoxysilane comprises one or more components selected from the group consisting of tetraethoxysilane and tetramethoxysilane.

Claim 10

The composition of claim 1 wherein the relatively high volatility solvent composition has a boiling point of about 120° C. or less.

Claim 11

The composition of claim 1 wherein the relatively high volatility solvent composition comprises one or more components selected form the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol and mixtures thereof.

Claim 12

The composition of claim 1 wherein the relatively low volatility solvent composition comprises di(ethylene)glycol, tri(ethylene)glycol, tetra(ethylene)glycol; penta(ethylene)glycol, di(propylene)glycol, hexa(ethylene)glycol or mixtures thereof.

Claim 13

The composition of claim 1 wherein the precursor composition has no more than about 250 parts per billion of trace metal impurities.

Claim 14

A process for forming a nanoporous dielectric coating on a substrate which comprises a) blending a nanoporous silica precursor composition comprising at least one alkoxysilane; at least one relatively low volatility solvent composition comprising an ether of a C 1 to C 4 alkylene glycol which is misciblc in water and alkoxysilanes, having a hydroxyl concentration of 0.021 mole/cm 3 or less, a boiling point of about 175° C. or more at atmospheric pressure and a weight average molecular weight of about 100 or more; at least one relatively high volatility solvent composition having a boiling point below that of the relatively low volatility solvent composition; optional water and an optional catalytic amount of an acid, thus forming a mixture and causing a partial hydrolysis and partial condensation of the alkoxysilane; b) depositing the composition onto a substrate while evaporating at least a portion of the relatively high volatility solvent composition; c) exposing the composition to a water vapor and a base vapor; and d) evaporating the relatively low volatility solvent composition, thereby forming a silicon containing polymer composition on the substrate, wherein the silicon containing polymer composition has a dielectric constant of from about 1.3 to about 3.5. and a density in the range of from about 0.25 to about 1.9 g/cm 3 .

Claim 15

A process for forming a nanoporous dielectric coating on a substrate which comprises a) blending a nanoporous silica precursor composition comprising at least one alkoxysilane; at least one relatively low volatility solvent composition comprising an ether of a C 1 to C 4 alkylene glycol which is misciblc in water and alkoxysilanes, having a hydroxyl concentration of 0.021 mole/cm 3 or less, a boiling point of about 175° C. or more at atmospheric pressure and a weight average molecular weight of about 100 or more; at least one relatively high volatility solvent composition having a boiling point below that of the relatively low volatility solvent composition; optional water and an optional catalytic amount of an acid, thus forming a mixture and causing a partial hydrolysis and partial condensation of the alkoxysilane; b) depositing the composition onto a substrate while evaporating at least a portion of the relatively high volatility solvent composition; c) exposing the composition to a water vapor and a base vapor; and d) evaporating the relatively low volatility solvent composition, thereby forming a silicon containing polymer composition on the substrate, wherein the silicon containing polymer composition has a dielectric constant of from about 1.3 to about 3.5. and a density in the range of from about 0.25 to about 1.9 g/cm 3 .

Claim 16

The process of claim 13 wherein step (a) comprises blending water in the composition.

Claim 17

The process of claim 13 wherein step (a) further comprises blending a catalytic amount of an acid in the composition.

Claim 18

The process of claim 13 wherein the alkoxysilane comprises one or more components selected from the group consisting of alkoxysilanes having the formula: ##STR3## wherein at least 2 of the R groups are independently C 1 to C 4 alkoxy groups and the balance, if any, are independently selected from the group consisting of hydrogen, allyl, phenyl, and halogen.

Claim 19

The process of claim 16 wherein each R is methoxy, ethoxy or propoxy.

Claim 20

The process of claim 13 wherein the alkoxysilane comprises one or more components selected from the group consisting of tetraethoxysilane and tetramethoxysilane.

Claim 21

The process of claim 13 wherein the relatively high volatility solvent composition has a boiling point of about 120° C. or less.

Claim 22

The process of claim 13 wherein the relatively high volatility solvent composition comprises one or more components selected form the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol and mixtures thereof.

Claim 23

The process of claim 13 wherein the relatively low volatility solvent composition comprises di(ethylene)glycol, tri(ethylene)glycol, tetra(ethylene)glycol; penta(ethylene)glycol, di(propylene)glycol, hexa(ethylene)glycol or mixtures thereof.

Claim 24

The process of claim 13 wherein the base vapor comprises one or more components selected from the group consisting of ammonia, amines and mixtures thereof.

Claim 25

The process of claim 13 wherein the mole ratio of water vapor to base vapor ranges from about 1:3 to about 1:100.

Claim 26

The process of claim 13 wherein the base vapor has a pKb of from about less than 0 to about 9.

Claim 27

The process of claim 13 wherein the substrate comprises raised pattern of lines comprising a metal, silica, silicon nitride, titanium nitride, tantalum nitride or silicon oxynitride.

Claim 28

The process of claim 13 wherein the substrate comprises a semiconductor material.

Claim 29

The process of claim 13 wherein the substrate comprises silicon or gallium arsenide.

Claim 30

The process of claim 13 wherein the mole ratio of water vapor to base vapor ranges from about 1:3 to about 1:100.

Claim 31

The process of claim 13 wherein the precursor composition has no more than about 250 parts per billion of trace metal impurities.