Low temperature silicon wafer bond process with bulk material bond strength

• US 6,423,613 B1
• Filed: 11/10/1998
• Issued: 07/23/2002
• Est. Priority Date: 11/10/1998
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Geusic, Joseph E.
• Primary Examiner(s): Sherry, Michael J.
• Assistant Examiner(s): PERT, EVAN T
• Application Number:
  US09/189,276
• Publication Number:
  US 20020076902A1
• Time in Patent Office: 1,351 Days
• Field of Search: 438/455, 438/799, 438/456, 438/457, 438/458, 438/459, 438/798
• US Class Current: 438/455
• CPC Class Codes: H01L 21/187 by direct bonding
• CPC Class Codes: H01L 21/76251 using bonding techniques

Abstract

The present invention includes a method for bonding one semiconductor surface to a second semiconductor surface. The method includes providing a first article that has a semiconductor surface and a second article that has a semiconductor surface. The semiconductor surfaces are annealed with an energy source wherein energy is confined to the semiconductor surfaces. The annealed surfaces are bonded to each other.

Claims

1. A method for bonding one semiconductor surface to a second semiconductor surface, comprising:

providing an article that has a semiconductor surface;

providing a second article that has a semiconductor surface;

annealing the semiconductor surfaces in a state of separation under a vacuum with an energy source wherein energy from the energy source is substantially confined to the semiconductor surfaces; and

contacting the semiconductor surface of the article to the second semiconductor surface of the second article to form a bond after annealing, while in a vacuum.

2. The method of claim 1 and further including fabricating an integrated circuit on or within a surface of the article which opposes the surface which is annealed.

3. The method of claim 2 wherein fabricating the integrated circuit is performed prior to annealing the semiconductor surfaces.

4. The method of claim 3 wherein the semiconductor surfaces are annealed at a temperature of at least about 600°

Centigrade while the integrated circuit temperature is within 15 to 25°

Centigrade of room temperature.

5. The method of claim 1 wherein the semiconductor surfaces are annealed with at least one laser pulse.

6. The method of claim 5 wherein the laser pulse is an incident optical pulse energy of approximately 243 joules, applied over the surface having a diameter of four inches.

7. The method of claim 5 wherein the laser pulse is generated by a q-switched ruby laser.

8. The method of claim 1 wherein annealing comprises exposing the energy source to the semiconductor surface incrementally over the semiconductor surface.

9. The method of claim 1 wherein annealing comprises exposing the energy source to the entire semiconductor surface in a single exposure.

10. The method of claim 1 and further including stripping any native oxide from at least one of the semiconductor surfaces prior to annealing.

11. The method of claim 1 wherein the articles are subjected to a temporary bonding prior to annealing.

12. The method of claim 11 wherein the articles are stored in an ultra clean environment prior to being subjected to a vacuum.

13. The method of claim 1 and further including treating at least one of the semiconductor surfaces to render the surface hydrophobic prior to annealing.

14. The method of claim 13 and further including temporarily bonding the treated surfaces to each other prior to annealing the surfaces.

15. The method of claim 14 wherein the bonded treated surfaces are subjected to an ultra-high vacuum.

16. The method of claim 15 and further including separating the surfaces prior to annealing, under a vacuum.

17. The method of claim 16 wherein the vacuum is approximately 3×

10<sup>−

9</sup> Torr.

18. A method for bonding one semiconductor wafer to another semiconductor wafer in order to maximize area and volume of a bonded wafer, comprising:

providing first and second semiconductor wafers;

annealing surfaces of the semiconductor wafers in a state of separation under vacuum with an energy source wherein energy from the energy source is substantially confined to the semiconductor surfaces and energy is sequentially applied to a fraction of each of the surfaces; and

bonding the annealed surfaces to each other, while under vacuum.

19. The method of claim 18 wherein the energy source is pulsed.

20. The method of claim 18 wherein the energy is sequentially applied so that a sum of the fractions comprises substantially an entire surface of the wafer.

21. The method of claim 18 wherein the energy is applied as a fraction of energy to a fraction of the wafer surface, as is applied to an entire wafer surface.

22. The method of claim 18 wherein each fraction to which energy is applied is approximately one-tenth of the surface of the wafer.

23. The method of claim 18 and further including mounting the silicon wafers on a stage.

24. The method of claim 23 wherein the stage is moveable in an x-axis and a y-axis in relation to a fixed energy source.

25. The method of claim 23 wherein the stage is fixed and the energy source is moveable.

26. The method of claim 23 and further including focusing energy from the energy source to impinge in a raster x and y movement across the wafer surface.