Method of forming a vacuum micro-chamber for encapsulating a microelectronics device

• US 5,354,714 A
• Filed: 08/26/1993
• Issued: 10/11/1994
• Est. Priority Date: 08/01/1991
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Boysel, R. Mark
• Primary Examiner(s): Thomas, Tom
• Assistant Examiner(s): Picardat, Kevin M.
• Application Number:
  US08/112,828
• Time in Patent Office: 411 Days
• Field of Search: 437/205, 437/214, 437/215, 437/216, 437/219, 437/21, 437/222, 437/223, 437/224, 437/65, 437/64
• US Class Current: 438/127
• CPC Class Codes: H01J 9/025 of field emission cathodes

Abstract

A method of forming a vacuum micro-chamber for encapsulating a microelectronics device in a vacuum processing chamber comprises the steps of forming a microelectronics device (14) on a substrate base (30). The next step is to cover microelectronics device (14) with an organic spacer such as photoresist in a form having a plurality of protrusions, such as a star shape form (36). The next step is to cover the organic spacer and substrate base (30) with the metal layer (24) so that the metal layer covers all of the organic spacer except for a predetermined number of access apertures (34) to the organic spacer. Next, the organic spacer is removed through access apertures (34) to cause metal layer (24) to form a shell over a vacuum chamber (20) between the microelectronics device (14) and metal layer (24). The next step is to seal vacuum chamber (20) by coating metal layer (24) and closing off access apertures (34). The method of the present invention has application to produce vacuum micro-diodes and micro-triodes, micro-mass spectrometers, micro-light bulbs, and micro-thermocouple gages, as well as numerous other applications.

Claims

1. A method of forming a vacuum micro-chamber for encapsulating a microelectronic device on a substrate, said method comprising the steps of:

a) forming a spacer material overlying said microelectronic device and a portion of said substrate adjacent to said microelectronic device;

b) forming a covering layer overlying and encompassing said spacer material except for at least one access aperture;

c) removing said spacer material through said at least one access aperture to form a chamber defined between said substrate and said covering layer; and

d) sealing said chamber by closing off said access aperture.

2. The method of claim 1 and further comprising the step of fixedly establishing a vacuum in said chamber by placing said chamber in an evacuated environment during said sealing step.

3. The method of claim 1 wherein said covering layer is a metal layer.

4. The method of claim 1 wherein said sealing step is accomplished by forming a metal seal over said access aperture.

5. The method of claim 1 wherein said metal layer is a low temperature metal layer.

6. The method of claim 1 wherein said metal layer is aluminum.

7. The method of claim 1 wherein said metal layer functions as the upper electrode of said microelectronic device to form a triode.

8. The method of claim 1 wherein said metal layer functions as the upper electrode of said microelectronic device to form a diode.

9. The method of claim 1 wherein said covering layer has a plurality of access apertures.

10. The method of claim 1 wherein said spacer material is an organic spacer.

11. The method of claim 1 wherein said spacer material is photoresist.

12. The method of claim 1 wherein said removing step is by isotropic plasma etching.

13. The method of claim 1 wherein said covering layer comprises lowered portions which are in contact with said substrate and a raised portion which is not in contact with said substrate, thereby forming said access aperture through said raised portion.

14. The method of claim 1 wherein said substrate is silicon.

15. The method of claim 1 wherein said substrate is gallium arsenide.

16. A method of forming a vacuum micro-chamber for encapsulating a microelectronic device on a substrate, said method comprising the steps of:

a) forming a spacer layer overlying said microelectronic device and said substrate;

b) patterning said spacer layer to form a spacer material overlying said microelectronic device and a portion of said substrate adjacent to said microelectronic device;

c) forming a metal layer overlying and encompassing said spacer material;

d) patterning said metal layer to form at least one access aperture therein;

e) removing said spacer material through said at least one access aperture by a isotropic plasma etch process to form a chamber defined between said substrate and said aluminum layer; and

f) fixedly establishing a vacuum in said chamber by sealing said chamber in an evacuated environment with a metal seal over said access aperture.

17. The method of claim 16 wherein said dry etch process is an isotropic plasma etch.

18. The method of claim 16 wherein said metal layer is aluminum.

19. The method of claim 16 wherein said patterned metal layer comprises lowered portions which are in contact with said substrate and a raised portion which is not in contact with said substrate, thereby forming said access aperture through said raised portion.

20. A method of forming a vacuum micro-chamber for encapsulating a microelectronic device on a substrate, said method comprising the steps of:

a) forming a spacer layer of photoresist overlying said microelectronic device and said substrate;

b) patterning said spacer layer to form a spacer material overlying said microelectronic device and a portion of said substrate adjacent to said microelectronic device;

c) forming a metal layer overlying and encompassing said spacer material;

d) patterning said metal layer to form at least one access aperture therein;

e) removing said spacer material through said at least one access aperture by a dry etch process to form a chamber defined between said substrate and said metal layer; and

f) fixedly establishing a vacuum in said chamber by sealing said chamber in an evacuated environment with a metal seal over said access aperture.