EP0775669A2
Expired / Lapsed
EP
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Low volatility solvent-based precursors for nanoporous aerogels
Assignee: Texas Instruments Inc
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Filing: 1996-11-14
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Granted: —
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Expires: 2016-11-14
Abstract
Abstract An aerogel precursor sol is disclosed herein. This aerogel precursor sol comprises a metal-based aerogel precursor reactant and a first solvent comprising a polyol; wherein, the molar ratio of the first solvent molecules to the metal atoms in the reactant is at least 1 : 16 . Preferably, the first solvent is glycerol. Preferably, the aerogel precursor reactant may selected from the group consisting of metal alkoxides, at least partially hydrolyzed metal alkoxides, particulate metal oxides, and combinations thereof. Typically, the molar ratio of the first solvent molecules to the metal atoms in the reactant is no greater than 12 : 1, and preferably, the molar ratio of the first solvent molecules to the metal atoms in the reactant is between 1 : 2 and 12 : 1. In some embodiments, the molar ratio of the first solvent molecules to the metal atoms in the reactant is between 2.5 :1 and 12:1. In some embodiments, the first solvent comprises a glycol. In some embodiments, the reactant is tetraethoxysilane that may be at least partially hydrolyzed. In some embodiments, the first polyol is selected from the group consisting of 1,2,4-butanetriol; 1,2,3- butanetriol; 2 methyl-propanetriol; and 2-(hydroxymethyl)-1,3-propanediol; 1-4, 1-4, butanediol; and 2-methyl-1,3-propanediol, and combinations thereof. This invention allows controlled porosity thin film nanoporous aerogels to be deposited, gelled, aged, and dried without atmospheric controls. In another aspect, this invention allows controlled porosity thin film nanoporous aerogels to be deposited, gelled, rapidly aged at an elevated temperature, and dried with only passive atmospheric controls, such as limiting the volume of the aging chamber.
Inventors
- 👤 Douglas M. Smith
- 👤 Gregory P. Johnston
- 👤 William C. Ackerman
- 👤 Shin-Puu Jeng
- 👤 Bruce E. Gnade
- 👤 Richard A. Stoltz
- 👤 Alok Maskara
- 👤 Teresa Ramos
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 04:47
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/69; H10P14/692; H10P14/6921; H10P14/6922; B; B01; B01J; B01J13/00; B01J13/0091; C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/14; C01B33/157; C01B33/158; C01B33/1585; C03; C03C; C03C1/00; C03C1/006; C03C1/008; C03C17/00; C03C17/22; C03C17/23; C03C17/25; H10P14/63; H10P14/6326; H10P14/6342; H10P14/65; H10P14/6516; H10P14/6529; H10P14/6534; H10P14/6546; H10P14/66; H10P14/665; H10P14/668; H10P14/6681; H10P14/6684; H10P14/6686; C03C2217/00; C03C2217/20; C03C2217/21; C03C2217/213; C03C2218/00; C03C2218/10; C03C2218/11; C03C2218/113
Claims Analysis
Total Claims: 79
Claim 1
Independent Claim
40 words
A metal-based nanoporous aerogel precursor sol, comprising an aerogel precursor reactant, and a first solvent comprising a polyol; wherein, the molar ratio of said first solvent molecules to the metal atoms in said reactant is at least 1 : 16.
Claim 2
Dependent Claim
59 words
A metal-based aerogel precursor sol, comprising an aerogel precursor reactant selected from the group consisting of metal alkoxides, at least partially hydrolyzed metal alkoxides, particulate metal oxides, and combinations thereof, and a first solvent comprising a polyol; wherein, the molar ratio of said first solvent molecules to the metal atoms in said reactant is at least 1 : 16.
Claim 3
Dependent Claim
13 words
The aerogel precursor sol according to Claim 2, wherein said polyol is glycerol.
Claim 4
Dependent Claim
31 words
The aerogel precursor sol according to Claim 2, wherein the molar ratio of said first solvent molecules to the metal atoms in said reactant is no greater than 12 : 1.
Claim 5
Dependent Claim
33 words
The aerogel precursor sol according to Claim 2, wherein the molar ratio of said first solvent molecules to the metal atoms in said reactant is between 1 : 2 and 12 : 1.
Claim 6
Dependent Claim
33 words
The aerogel precursor sol according to Claim 2, wherein the molar ratio of said first solvent molecules to the metal atoms in said reactant is between 1 : 4 and 4 : 1.
Claim 7
Dependent Claim
33 words
The aerogel precursor sol according to Claim 2, wherein the molar ratio of said first solvent molecules to the metal atoms in said reactant is between 2.5 : 1 and 12 : 1.
Claim 8
Dependent Claim
28 words
The aerogel precursor sol according to Claim 2, wherein said reactant is a metal alkoxide selected from the group consisting of tetraethoxysilane, tetramethoxysilane, methyltriethoxysilane, 1,2-Bis(trimethoxysilyl)ethane and combinations thereof.
Claim 9
Dependent Claim
13 words
The aerogel precursor sol according to Claim 2, wherein said reactant is tetraethoxysilane.
Claim 10
Dependent Claim
16 words
The aerogel precursor sol according to Claim 9, wherein said tetraethoxysilane is at least partially hydrolyzed.
Claim 11
Dependent Claim
11 words
The aerogel precursor sol according to Claim 2, further comprising water.
Claim 12
Dependent Claim
15 words
The aerogel precursor sol according to Claim 2, wherein said first solvent is ethylene glycol.
Claim 13
Dependent Claim
13 words
The aerogel precursor sol according to Claim 2, further comprising a second solvent.
Claim 14
Dependent Claim
15 words
The aerogel precursor sol according to Claim 13, wherein said second solvent is an alcohol.
Claim 15
Dependent Claim
14 words
The aerogel precursor sol according to Claim 13, wherein said second solvent is ethanol.
Claim 16
Dependent Claim
14 words
The aerogel precursor sol according to Claim 2, further comprising a pH modification agent.
Claim 17
Dependent Claim
12 words
The aerogel precursor sol according to Claim 2, further comprising an acid.
Claim 18
Dependent Claim
14 words
The aerogel precursor sol according to Claim 17, wherein said acid is nitric acid.
Claim 19
Dependent Claim
19 words
The aerogel precursor sol according to Claim 2, wherein the pH of said sol is between 3 and 5.
Claim 20
Dependent Claim
13 words
The aerogel precursor sol according to Claim 2, further comprising a gelation catalyst.
Claim 21
Dependent Claim
15 words
The aerogel precursor sol according to Claim 20, wherein said gelation catalyst is ammonium hydroxide.
Claim 22
Dependent Claim
19 words
The aerogel precursor sol according to Claim 20, wherein the pH of said sol is between 7 and 9.
Claim 23
Dependent Claim
20 words
The aerogel precursor sol according to Claim 2, wherein the viscosity of said sol is between 1 and 12 centipoise.
Claim 24
Dependent Claim
20 words
The aerogel precursor sol according to Claim 2, wherein the viscosity of said sol is between 1 and 5 centipoise.
Claim 25
Dependent Claim
25 words
The aerogel precursor sol according to Claim 2, wherein said reactant is selected from the group consisting of pyrogenic silica, colloidal silica, and combinations thereof.
Claim 26
Dependent Claim
13 words
An aerogel precursor sol, comprising At least partially hydrolyzed tetraethoxysilane and ethylene glycol.
Claim 27
Dependent Claim
26 words
The aerogel precursor sol according to Claim 26, wherein the molar ratio of ethylene glycol to tetraethoxysilane is between 1 : 16 and 12 : 1.
Claim 28
Dependent Claim
40 words
A silicon-based aerogel precursor sol, comprising a silicon based aerogel precursor, and a first solvent comprising a polyol; wherein, the molar ratio of said first solvent molecules to the silicon atoms in said reactant is at least 1 : 16.
Claim 29
Dependent Claim
31 words
The aerogel precursor sol according to Claim 28, wherein the molar ratio of said first solvent molecules to the metal atoms in said reactant is no greater than 12 : 1.
Claim 30
Dependent Claim
12 words
An aerogel precursor sol, comprising at least partially hydrolyzed tetraethoxysilane and glycerol.
Claim 31
Dependent Claim
25 words
The aerogel precursor sol according to Claim 30, wherein the molar ratio of glycerol to tetraethoxysilane is between 1 : 16 and 12 : 1.
Claim 32
Dependent Claim
25 words
The aerogel precursor sol according to Claim 30, wherein the molar ratio of glycerol to tetraethoxysilane is between 1 : 4 and 4 : 1.
Claim 33
Dependent Claim
142 words
A non-supercritical method of forming a nanoporous aerogel, said method comprising the steps of: providing an aerogel precursor sol, said sol comprising an at least partially hydrolyzed metal alkoxide dispersed in a first solvent and a second solvent, evaporating substantially all of said second solvent while preventing substantial evaporation of said first solvent, and allowing the sol to create a gel, wherein the gel comprises a porous solid and a pore fluid; continuing to prevent substantial evaporation of said first solvent from said sol until a drying step, wherein said drying step comprises forming a dry aerogel by removing the pore fluid in a non-supercritical drying atmosphere without substantial collapse of the porous solid; whereby the skeletal density of the dry aerogel is determined approximately by the volume ratio of said metal alkoxide to said first solvent in said aerogel precursor sol.
Claim 34
Dependent Claim
15 words
The method of claim 33, wherein said gel is created before said evaporating step completes.
Claim 35
Dependent Claim
14 words
The method of claim 33, wherein said drying step further comprises a solvent exchange.
Claim 36
Dependent Claim
14 words
The method of claim 33, further comprising aging said gel before said drying step.
Claim 37
Dependent Claim
71 words
A non-supercritical method of forming an aerogel film on a substrate, said method comprising the steps of: depositing a film of an aerogel precursor sol on a substrate, said sol comprising a first solvent and a second solvent; preferentially evaporating substantially all of said second solvent from said film; and allowing said deposited sol to cross-link to form a wet gel having pores arranged in an open-pored structure on said substrate.
Claim 38
Dependent Claim
17 words
The method of claim 37, wherein said second solvent comprises a reaction product of said cross-linking step.
Claim 39
Dependent Claim
25 words
The method of claim 37, wherein said second solvent has a vapor pressure which is at least twice the vapor pressure of said first solvent.
Claim 40
Dependent Claim
21 words
The method of claim 37, wherein said depositing a thin film step comprises spin-coating said aerogel precursor sol onto said substrate.
Claim 41
Dependent Claim
22 words
The method of claim 37, further comprising drying said wet gel in a non-supercritical atmosphere without substantial densification of said open-pored structure.
Claim 42
Dependent Claim
16 words
The method of claim 37, wherein said wet gel is formed before said evaporating step completes.
Claim 43
Dependent Claim
18 words
The method of claim 37, further comprising aging said wet gel without substantial evaporation of said first solvent.
Claim 44
Dependent Claim
116 words
A non-supercritical method for forming a thin film aerogel on a semiconductor substrate, the method comprising the steps of: a) providing a semiconductor substrate comprising a microelectronic circuit; b) depositing an aerogel precursor sol upon the substrate; wherein the aerogel precursor sol comprises a metal-based aerogel precursor reactant, a first solvent comprising glycerol, and a second solvent; wherein, the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is at least 1 : 16. c) allowing the deposited sol to create a gel, wherein the gel comprises a porous solid and a pore fluid; and d) forming a dry aerogel by removing the pore fluid in a non-supercritical drying atmosphere.
Claim 45
Dependent Claim
13 words
The method of claim 44, wherein the first solvent also comprises a polyol.
Claim 46
Dependent Claim
11 words
The method of claim 45, wherein the polyol is a glycol.
Claim 47
Dependent Claim
119 words
A non-supercritical method for forming a thin film nanoporous dielectric on a semiconductor substrate, the method comprising the steps of: a) providing a semiconductor substrate comprising a microelectronic circuit; b) depositing an aerogel precursor sol upon the substrate; wherein the aerogel precursor sol comprises a metal-based aerogel precursor reactant, and a first solvent comprising glycerol, and a second solvent; wherein, the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is at least 1 : 16. c) allowing the deposited sol to create a gel, wherein the gel comprises a porous solid and a pore fluid; and d) forming a dry, nanoporous dielectric by removing the pore fluid in a non-supercritical drying atmosphere.
Claim 48
Dependent Claim
166 words
A non-supercritical method for forming a thin film nanoporous dielectric on a semiconductor substrate, the method comprising the steps of: a) providing a semiconductor substrate comprising a microelectronic circuit; b) depositing an aerogel precursor sol upon the substrate; wherein the aerogel precursor sol comprises an aerogel precursor reactant selected from the group consisting of metal alkoxides, at least partially hydrolyzed metal alkoxides, particulate metal oxides, and combinations thereof, and a first solvent comprising glycerol; wherein, the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is at least 1 : 16. c) allowing the deposited sol to create a gel, wherein the gel comprises a porous solid and a pore fluid; and d) forming a dry, nanoporous dielectric by removing the pore fluid without substantially collapsing the porous solid; wherein, the forming step is performed in a drying atmosphere, and the pressure of the drying atmosphere during the forming step is less than the critical pressure of the pore fluid.
Claim 49
Dependent Claim
29 words
The method of claim 48, wherein the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is no greater than 12 : 1.
Claim 50
Dependent Claim
31 words
The method of claim 48, wherein the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is between 1 : 2 and 12 : 1.
Claim 51
Dependent Claim
31 words
The method of claim 48, wherein the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is between 1 : 4 and 4 : 1.
Claim 52
Dependent Claim
31 words
The method of claim 48, wherein the molar ratio of the molecules of the glycerol to the metal atoms in the reactant is between 2.5 : 1 and 12 : 1.
Claim 53
Dependent Claim
24 words
The method of claim 48, wherein the nanoporous dielectric has a porosity greater than 60% and an average pore diameter less than 20 nm.
Claim 54
Dependent Claim
16 words
The method of claim 48, wherein the nanoporous dielectric has a dielectric constant less than 2.0.
Claim 55
Dependent Claim
16 words
The method of claim 48, wherein the nanoporous dielectric has a dielectric constant less than 1.8.
Claim 56
Dependent Claim
16 words
The method of claim 48, wherein the nanoporous dielectric has a dielectric constant less than 1.4.
Claim 57
Dependent Claim
24 words
The method of claim 48, wherein the temperature of the substrate during the forming step is above the freezing temperature of the pore fluid.
Claim 58
Dependent Claim
43 words
The method of claim 48, wherein the temperature of the substrate during the forming step is above the freezing temperature of the pore fluid, and wherein, the method does not comprise the step of adding a surface modification agent before the forming step.
Claim 59
Dependent Claim
61 words
The method of claim 48, wherein the temperature of the substrate during the forming step is above the freezing temperature of the pore fluid, and the nanoporous dielectric has a porosity greater than 60% and an average pore diameter less than 20 nm; wherein, the method does not comprise the step of adding a surface modification agent before the forming step.
Claim 60
Dependent Claim
13 words
The method of claim 48, further comprising the step of aging the gel.
Claim 61
Dependent Claim
20 words
The method of claim 60, wherein at least part of the aging step is performed in a substantially closed container.
Claim 62
Dependent Claim
20 words
The method of claim 60, wherein the temperature of the gel during the aging is greater than 30 degrees C.
Claim 63
Dependent Claim
20 words
The method of claim 60, wherein the temperature of the gel during the aging is greater than 80 degrees C.
Claim 64
Dependent Claim
20 words
The method of claim 60, wherein the temperature of the gel during the aging is greater than 130 degrees C.
Claim 65
Dependent Claim
21 words
The method of claim 48, wherein the porous solid has less than 2% permanent volume reduction during the pore fluid removal.
Claim 66
Dependent Claim
17 words
The method of claim 48, wherein the porous solid remains substantially uncollapsed after the pore fluid removal.
Claim 67
Dependent Claim
20 words
The method of claim 48, wherein the porous solid has less than 5% volume reduction during the pore fluid removal.
Claim 68
Dependent Claim
20 words
The method of claim 48, wherein the porous solid has less than 1% volume reduction during the pore fluid removal.
Claim 69
Dependent Claim
33 words
The method of claim 48, wherein the allowing step is performed in a gelation atmosphere, wherein the concentration of a vapor of the first solvent in the gelation atmosphere is not actively controlled.
Claim 70
Dependent Claim
32 words
The method of claim 48, wherein the allowing step is performed in a gelation atmosphere, wherein the concentration of a vapor of the first solvent in the gelation atmosphere is substantially uncontrolled.
Claim 71
Dependent Claim
25 words
The method of claim 48, wherein the reactant is a metal alkoxide selected from the group consisting of tetraethoxysilane, tetramethoxysilane, methyltriethoxysilane, 1,2-Bis(trimethoxysilyl)ethane and combinations thereof.
Claim 72
Dependent Claim
10 words
The method of claim 48, wherein the reactant is tetraethoxysilane.
Claim 73
Dependent Claim
16 words
The method of claim 48, wherein the dry, porous dielectric has a porosity greater than 60%.
Claim 74
Dependent Claim
18 words
The method of claim 48, wherein the dry, porous dielectric has a porosity between 60 % and 90%.
Claim 75
Dependent Claim
16 words
The method of claim 48, wherein the dry, porous dielectric has a porosity greater than 80%.
Claim 76
Dependent Claim
27 words
The method of claim 48, further comprising the step of replacing at least part of the pore fluid with a liquid before the removing pore fluid step.
Claim 77
Dependent Claim
10 words
The method of claim 76, wherein the liquid comprises hexanol.
Claim 78
Dependent Claim
15 words
The method of claim 48, further comprising the step of annealing the dry, porous dielectric.
Claim 79
Dependent Claim
21 words
The method of claim 48, wherein the pressure of the drying atmosphere during the forming step is less than 3 MPa.
References Cited (Backward Citations)
US5470802A
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