System and method for bonding and sealing microfabricated wafers to form a single structure having a vacuum chamber therein

• US 6,090,687 A
• Filed: 07/29/1998
• Issued: 07/18/2000
• Est. Priority Date: 07/29/1998
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Hoen, Storrs, Merchant, Paul P.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): LATTIN, CHRISTOPHER W
• Application Number:
  US09/124,311
• Time in Patent Office: 720 Days
• Field of Search: 438/455, 438/456, 438/118, 438/106, 438/119, 438/127, 438/126, 438/650
• US Class Current: 438/455
• CPC Class Codes: H01L 21/50 Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01079 Gold [Au]

Abstract

A palladium contact and a gasket are formed on a first wafer. The gasket and contact are simultaneously engaged with a silicon layer of a second wafer. The wafers are then heated to a temperature that both forms a bond between the palladium contact of the first wafer with the silicon layer of the second wafer and that fuses the gasket to the second wafer. Therefore, when the temperature is decreased, the palladium-silicon bond maintains the alignment of the two wafers with respect to one another, and the gasket hardens to form seal around a periphery of the two wafers. By placing the two wafers in a vacuum environment prior to engaging the two wafers, the space encompassed by the gasket and the two wafers forms a sealed vacuum during the heating process. Therefore, the heating process not only forms a palladium-silicon bond between the two wafers, but it also forms a vacuum seal around selected components included within either of the two wafers.

Claims

1. A method, comprising steps of:

providing a first wafer having palladium on a surface of said first wafer;

providing a second wafer having silicon on a surface of said second wafer;

providing a gasket on one of said wafers;

engaging said gasket with the other one of said wafers;

engaging said palladium with said silicon; and

increasing a temperature of said wafers in order to form a bond between said palladium and said silicon and in order to form a seal between said first wafer and said second wafer.

2. The method of claim 1, further including a step of forming an eutectic between said gasket and said one of said wafers during said increasing step.

3. The method of claim 1, further including steps of:

increasing said temperature to a particular temperature;

forming said bond at said particular temperature; and

forming said seal at said particular temperature.

4. The method of claim 3, further including a step of creating a vacuum around said first and second wafers prior to said engaging said palladium step and said increasing step.

5. The method of claim 3, further including a step of engaging gold elements within said gasket to said other one of said wafers.

6. The method of claim 4, further including a step of deforming said gasket during said engaging said gasket step.

7. The method of claim 4, further including a step of maintaining an alignment of said second wafer with respect to said first wafer via said bond.

8. The method of claim 5, further comprising steps of:

providing a germanium layer on said other one of said wafers prior to said engaging said gasket step; and

engaging said germanium layer with said gasket.

9. The method of claim 7, further including a step of maintaining said vacuum around selected components of one of said wafers with said seal.

10. A method for evacuating a chamber within a structure, comprising steps of:

providing a first wafer including a contact on said first wafer;

engaging said contact with a second wafer;

engaging a gasket with one of said wafers;

forming a vacuum around said first and second wafers;

annealing said wafers subsequent to said forming a vacuum step in order to form a bond between said contact and said second wafer; and

melting eutectic material between said gasket and said one of said wafers during said annealing step.

11. The method of claim 10, further including a step of deforming said gasket.

12. The method of claim 10, further including steps of:

maintaining an alignment of said wafers via said bond; and

maintaining said vacuum within said structure via said seal.

13. The method of claim 10, wherein said eutectic includes gold.

14. The method of claim 13, wherein said eutectic includes germanium.

15. The method of claim 10, further including a step of bonding palladium to silicon to form said bond.

16. The method of claim 15, further including a step of fusing gold elements within said gasket to said one of said wafers.

17. The method of claim 16, further including a step of engaging material including germanium with said gasket during said engaging a gasket step.