Process for preparing an epitaxial alpha-quartz layer on a solid support, material obtained and uses thereof

Patent metadata

Field	Value
Publication number	US-10053795-B2
Application number	US-201314416098-A
Country	US
Kind code	B2
Filing date	Jul 22, 2013
Priority date	Jul 23, 2012
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

The present invention relates to a process for preparing epitaxial α-quartz layers on a solid substrate, to the material obtained according to this process, and to the various uses thereof, especially in the electronics field.

First claim

The invention claimed is:

1. Process for preparing an epitaxial α-quartz layer on a solid support, comprising the following steps:
i) a step of preparing a composition containing, in a solvent, at least one silica and/or colloidal silica precursor;
ii) a step of depositing a layer of the composition obtained above in step i) onto at least part of the surface of a substrate and the formation of an amorphous silica matrix layer;
iii) a step of heat treatment of the amorphous silica matrix layer obtained in step ii) to obtain an epitaxial α-quartz layer,
wherein:
the substrate is a self-supporting mono-oriented crystalline silicon substrate comprising a layer of native amorphous SiO 2 , and in that
the step of heat treatment of the amorphous silica layer is performed at a temperature of greater than or equal to 800° C., in the presence of at least one catalyst based on one of the following elements in oxidation state (+2): strontium, barium, calcium, magnesium, beryllium, or one of the following elements in oxidation state (+1): caesium, rubidium, lithium, sodium or potassium, or capable of generating one of the following elements in oxidation state (+2): strontium, barium, calcium, magnesium, beryllium, or one of the following elements in oxidation state (+1): caesium, rubidium, sodium, potassium or lithium, said catalyst being present in said amorphous silica matrix.

2. Process according to claim 1 , wherein the heat treatment step is performed in the presence of oxygen.

3. Process according to claim 1 , wherein the catalyst is present in the composition prepared in step i) and represents from 0.2 mol % to 30 mol % relative to the silica precursor and/or the colloidal silica precursor.

4. Process according to claim 1 , wherein the catalyst is introduced into the amorphous silica matrix at the end of step ii) and before performing the heat treatment step iii) and the amorphous silica matrix layer is impregnated with an impregnation solution containing at least said catalyst in a solvent.

5. Process according to claim 4 , wherein the concentration of catalyst in said impregnation solution ranges from 0.2 mol % to 50 mol %.

6. Process according to claim 1 , wherein the catalyst(s) present in the composition prepared in step i) or in the impregnation solution for the amorphous silica matrix layer are strontium, barium, calcium, magnesium or beryllium salts, chosen from the nitrates, sulfates, carbonates, hydroxides, chlorides, acetates, perchlorates, oxides and alkoxides.

7. Process according to claim 1 , wherein the catalyst(s) present in the composition prepared in step i) or in the impregnation solution for the amorphous silica matrix layer are caesium, rubidium, sodium, potassium or lithium salts chosen from the nitrates, sulfates, carbonates, hydroxides, chlorides, acetates, perchlorates, oxides and alkoxides.

8. Process according to claim 1 , wherein the silica precursor(s) that may be used in the composition prepared in step i) are chosen from silicon alkoxides, silicon tetrachloride, silicates and silicic acid, and mixtures thereof.

9. Process according to claim 8 , wherein the silicon alkoxides are chosen from tetramethoxysilane, tetraethoxyorthosilane, (3-mercaptopropyl)-trimethoxysilane, (3-aminopropyl)triethoxysilane, N-(3-trimethoxysilylpropyl)pyrrole, 3-(2,4-dinitrophenylamino)propyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, phenyltriethoxysilane and methyltriethoxysilane.

10. Process according to claim 1 , wherein the silica and/or colloidal silica precursor(s) represent from 0.01% to 95% by mass relative to the total mass of the composition prepared in step i).

11. Process according to claim 1 , wherein the composition prepared in step i) also contains one or more additives chosen from pH regulators, structuring or modifying agents, and porosity promoters.

12. Process according to claim 1 , wherein the heat treatment step iii) is performed at a temperature ranging from 800 to 1200° C.

13. Process according to claim 1 , wherein steps i) to iii) are repeated one or more times on the same substrate so as to form successive quartz layers superposed one on the other, or else on different zones of the same substrate.

14. Process according to claim 1 , wherein the process is a sol-gel process in which:
the composition used in step i) is a sol-gel composition containing, in a solvent, at least one silica precursor,
the formation of the amorphous silica matrix layer on the surface of the substrate is performed by evaporating the solvent contained in the sol-gel composition,
the substrate is a mono-oriented crystalline silicon substrate,
the step of heat treatment of the silica layer is performed in the presence of oxygen and at atmospheric pressure, and
the catalyst is a catalyst based on strontium, barium or calcium in oxidation state (+2) or which is capable of generating strontium, barium or calcium in oxidation state (+2).

15. Process according to claim 14 , wherein the catalyst is a catalyst based on strontium or barium in oxidation state (+2) or capable of generating strontium or barium in oxidation state (+2).

16. Process according to claim 14 , wherein the catalyst is present in the composition prepared in step i), and said composition also contains one or more surfactants.

17. Process according to claim 16 , wherein the surfactant(s) are chosen from cationic surfactants chosen from tetradecyltrimethylammonium bromide, dodecyltrimethylammonium bromide and cetyltrimethylammonium bromide; anionic surfactants chosen from sodium dodecyl sulfate, sodium dodecylsulfonate and sodium dioctylsulfosuccinate; and nonionic surfactants chosen from block copolymers of ethylene glycol and of propylene glycol.

Assignees

• Centre Nat Rech Scient
• Consejo Superior Investigacion
• Univ Pierre Et Marie Curie Paris 6

Inventors

• Boissiere Cedric
• Carretero-Genevrier Adrien
• Gich Marti
• Grosso David
• Sanchez Clement

Classifications

• C30B29/18

  Quartz · CPC title

• C30B1/023 Primary

  from solids with amorphous structure · CPC title

• Y10T428/249969

  Of silicon-containing material [e.g., glass, etc.] · CPC title

• C30B1/00

  Single-crystal growth directly from the solid state (unidirectional demixing of eutectoid materials C30B3/00; under a protective fluid C30B27/00) · CPC title

• C30B1/026

  Solid phase epitaxial growth through a disordered intermediate layer · CPC title