Method for the production of a microstructure comprising a vacuum cavity and a microstructure

• US 20050118920A1
• Filed: 04/01/2003
• Published: 06/02/2005
• Est. Priority Date: 04/12/2002
• Status: Abandoned Application

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Thomas, Isabelle, Lefort, Pierre-Olivier
• Application Number:
  US10/510,385
• Publication Number:
  US 20050118920A1
• Time in Patent Office: Days
• US Class Current: 445/24
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 2201/0115 Porous silicon

Abstract

The invention relates to a process for fabricating a microstructure containing a vacuum cavity. The invention includes producing, from a first silicon wafer, a porous silicon region intended to form, completely or partly, one wall of the cavity and capable of absorbing residual gases in the cavity and joins the first silicon wafer to a second wafer, so as to produce the cavity.

Claims

1. A process of fabricating a microstructure having a vacuum cavity, comprising the following steps:

a) producing, in the thickness of a first silicon wafer, a porous silicon region intended to format least a part of one wall of the cavity and capable of absorbing residual gases in the cavity; and

b) joining the first silicon wafer to a second wafer, so as to produce the cavity.

2. The process as claimed in claim 1, wherein step a) furthermore includes a step of impregnating the porous silicon region with another material that can also absorb residual gases in the cavity.

3. The process as claimed in claim 1, wherein when the cavity has a predetermined height, the joining operation of step b) is carried out by means of an intermediate wafer whose thickness contributes to the height of the cavity.

4. The process as claimed in claim 1, wherein prior to step b), the process includes a step of carrying out a physico-chemical preparation of the surfaces of the wafers used in step b).

5. The process as claimed in claim 1, wherein prior to step b), the process includes a step of outgasing the wafers used in step b).

6. The process as claimed in claim 1, wherein the joining operation of step b) is carried out under vacuum.

7. The process as claimed in claim 6, wherein the joining operation is carried out by bonding at ambient temperature.

8. The process as claimed in claim 7, wherein the process includes a step c) of annealing, at between 400 and 1000°

C., the microstructure obtained after step b) so as to strengthen the bond.

9. The process as claimed in claim 2, wherein the other material that can also absorb the residual gases in the cavity consists of titanium.

10. The process as claimed in claim 1, wherein the second wafer and/or the intermediate wafer are made of silicon or glass.

11. The process as claimed in claim 1, wherein the process is applied collectively to several micro structures.

12. A microstructure having a vacuum cavity, comprising:

at least two wafers that contribute to bounding the cavity, the first wafer of said two wafers, is made of silicon and includes a porous silicon region capable of absorbing residual gases in the cavity, the region being produced in the thickness of said silicon wafer.

13. The microstructure as claimed in claim 12, wherein the porous silicon region is impregnated with another material that can also absorb residual gases in the cavity.

14. The microstructure as claimed in claim 13, wherein the other material that can also absorb residual gases in the cavity is titanium.

15. The microstructure as claimed in claim 12, wherein the wafers other than the first wafer are made of silicon or glass, or a combination of silicon and glass.

16. The microstructure as claimed in claim 12, wherein said microstructure includes a resonator housed in the cavity.

17. A sensor having a microstructure as claimed in claim 12.

18. The sensor as claimed in claim 17, wherein the sensor is a resonant pressure sensor or a resonator accelerometer or a vibrating gyroscope or an electromechanical filter.