Adhesive of a silicon and silica composite particularly useful for joining silicon parts

• US 20040213955A1
• Filed: 09/25/2003
• Published: 10/28/2004
• Est. Priority Date: 04/23/2003
• Status: Active Grant

• Current Assignee: Hangzhou Dunyuanjuxin Semiconductor Technology Company Limited
• Original Assignee: Integrated Materials, Inc. (Ferrotec Holdings Corporation)
• Inventors: Boyle, James E., Zehavi, Raanan, Chalzel, Amnon
• Granted Patent: US 7,083,694 B2
• Time in Patent Office: Days
• US Class Current: 428/119
• CPC Class Codes: H01L 21/67306 characterized by a material, a roughness, a coating or the like
• CPC Class Codes: Y10T 428/24174 including sheet or component perpendicular to plane of web or sheet
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/252 Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension

Abstract

A method of joining two silicon members, the adhesive used for the method, and the joined product, especially a silicon tower for supporting multiple silicon wafers. A flowable adhesive is prepared comprising silicon particles of size less than 100 μm and preferably less than 100 nm and a silica bridging agent, such as a spin-on glass. Nano-silicon crystallites of about 20 nm size may be formed by CVD. Larger particles may be milled from virgin polysilicon. If necessary, a retardant such as a heavy, preferably water-insoluble alcohol such as terpineol is added to slow setting of the adhesive at room temperature. The mixture is applied to the joining areas. The silicon parts are assembled and annealed at a temperature sufficient to link the silica, preferably at 900° C. to 1100° C. for nano-silicon but higher for milled silicon.

Claims

1. A method of joining two silicon parts along respective joining areas, comprising the step:

providing a flowable mixture of a silicon powder and a silica bridging agent;

applying said flowable mixture to at least one of said joining areas;

assembling said two silicon parts with said respective joining areas in juxtaposition; and

annealing said assembled parts at an annealing temperature sufficient to convert said silica bridging agent to a silica network.

2. The method of claim 1, wherein said annealing temperature is at least 400°

C.

3. The method of claim 2, wherein said annealing temperature is between 900°

C. and 1100°

C.

4. The method of claim 2, wherein said annealing temperature is at least 1200°

C.

5. The method of claim 4, wherein said annealing temperature is at least 1300°

C.

6. The method of claim 1, wherein said silicon powder comprises virgin polysilicon.

7. The method of claim 1, wherein said silicon powder has a size of less than 100 μ

m.

8. The method of claim 7, wherein said size is between 1 and 50 μ

m.

9. The method of claim 1, wherein said silicon powder has a size distribution with a median size in a range of 10 nm to 25 nm.

10. The method of claim 1, wherein said silicon powder has a size distribution with at least 99% of particles having a size of less than 100 nm.

11. The method of claim 1, wherein said silicon powder is formed by a CVD process creating particles of silicon.

12. The method of claim 1, wherein said silica bridging agent comprises a silicone-containing material.

13. The method of claim 1, wherein said silica bridging agent comprises a spin-on glass.

14. The method of claim 13, wherein said flowable mixture consists of said spin-on glass and said silicon powder.

15. The method of claim 14, wherein said silicon powder has a size distribution with at least 99% of particles having a size of less than 100 nm.

16. The method of claim 13, wherein said flowable mixture further comprises a retardant to slow setting of said silica bridging agent at room temperature.

17. The method of claim 16, wherein said silica bridging agent comprises a spin-on glass and said retardant comprises an alcohol including less than 1% water.

18. The method of claim 1, wherein said parts form part of a wafer support fixture.

19. A joined silicon assembly, comprising:

at least two silicon parts juxtaposed across respective pairs of joining areas separated by respective gaps; and

a composite bridging said gaps and comprising silicon crystallites having sizes of less than 100 μ

m embedded in a matrix of silica.

20. The assembly of claim 19, wherein said crystallites have a size distribution with at least 99% of particles of size of less than 100 nm.

21. The assembly of claim 19 configured as a support fixture for supporting a plurality of substrates in parallel orientations spaced along an axis of the fixture.

22. A substrate support fixture, comprising:

a plurality of silicon legs including teeth for supporting a plurality of substrate in parallel orientations;

two silicon bases joined to opposing ends of said legs across respective joints with respective gaps between a respective one of said bases and a respective one of said legs;

silicon crystallites having sizes of less than 100 μ

m occupying at least 50% of said gaps; and

a silica network in each of said gaps joining said silicon crystallites and said legs and said bases.

23. The fixture of claim 22, wherein said sizes are between 1 and 751 μ

m.

24. The fixture of claim 22, wherein said silicon crystallites have a size distribution with at least 99% of particles having a size of less than 100 nm.

25. The fixture of claim 22, wherein said legs comprise an arcuate back side opposite said tips of said teeth supporting said substrates.

26. A silicon support tower, comprising:

two silicon bases; and

at least three silicon legs joined to said bases, each comprising on a front side a plurality of teeth having support surfaces for supporting a plurality of substrates in parallel orientation and on a back side an arcuate surface about a median plane of said teeth matching arcuate surfaces formed in said bases.

27. The tower of claim 26, further comprising a silicon and silica composite joining said bases and said legs.

28. An adhesive for joining two parts, comprising a mixture flowable a room-temperature application temperature composed of:

silicon particles having sizes of less than 100 μ

m; and

a silica bridging agent in which said particles are dispersed and which chemically reacts to form a silica network when annealed at an elevated temperature above said application temperature.

29. The adhesive of claim 28, wherein said silica bridging agent is a silicon-containing material.

30. The adhesive of claim 28, wherein said silica bridging agent is a spin-on glass.

31. The adhesive of claim 28, wherein 99% of said particles have a size of less than 100 nm.

32. The adhesive of claim 28, wherein said particles have size distribution with a median size in a range of 10 to 25 nm.