Fabrication method for digital micro-mirror devices using low temperature CVD

• US 5,526,951 A
• Filed: 09/30/1994
• Issued: 06/18/1996
• Est. Priority Date: 09/30/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Baker, James C., Bailey, Wayne E.
• Primary Examiner(s): Bowers, Jr., Charles L.
• Assistant Examiner(s): McPherson, John A.
• Application Number:
  US08/316,307
• Time in Patent Office: 627 Days
• Field of Search: 156/644.1, 216/24, 216/39, 430/321, 430/320, 437/228, 437/245, 427/162
• US Class Current: 216/24
• CPC Class Codes: C23C 16/04 Coating on selected surface areas, e.g. using masks
• CPC Class Codes: C23C 16/12 Deposition of aluminium only

Abstract

An improved support post (16, 23) for micro-mechanical devices (10). A conductive layer (33, 71) is deposited on a substrate at all places where the support posts (16, 23) are to be located. A spacer layer (41, 81) is then deposited and etched to form vias (41a, 81a). Each via (41a, 81a) defines the outer surface of a support post (16, 23). The bottom surface of each via is at the conductive layer (33, 71). This permits an aluminum CVD process to selectively fill the vias (41a, 81a), thereby forming the support posts (16, 23).

Claims

1. An improved method of fabricating a support post for a micro-mechanical device having at least one mechanical element supported by said support post, comprising the steps of:

depositing a conductive layer on a substrate;

depositing a spacer layer over said conductive layer;

etching vias into said spacer layer, each via defining an outer surface of a support post, said etching step being performed through said spacer layer such that each said via is bottomed by said conductive layer;

subjecting said spacer layer to an aluminum chemical vapor deposition on its surface; and

continuing said subjecting step until said vias are filled with aluminum to a desired height.

2. The method of claim 1, wherein said step of depositing a conductive layer is performed with a material that contains titanium.

3. The method of claim 1, wherein said step of depositing a conductive layer is performed such that said conductive layer is approximately 300 angstroms thick.

4. The method of claim 1, wherein said step of depositing a spacer layer is performed with photoresist.

5. The method of claim 1, wherein said subjecting step is performed at a temperature less than 400 degrees centigrade.

6. An improved method of fabricating a support for digital micro-mirror device, said device having a substrate upon which mirror elements having the following elements are fabricated:

a hinge support post, a hinge extending from said hinge support post, a mirror attached to said hinge, wherein said hinge is deformable so as to permit said mirror to deflect upon being subjected to an applied force, comprising the steps of;

depositing a conductive layer on the substrate;

depositing a spacer layer over said conductive layer;

etching vias into said spacer layer, each via defining an outer surface of a hinge support post, said etching step being performed through said spacer layer such that each said via is bottomed by said conductive layer;

subjecting said spacer layer to an aluminum chemical vapor deposition on its surface; and

continuing said subjecting step until said vials are filled with aluminum to a desired height.

7. The method of claim 6, wherein said step of depositing a conductive layer is performed with a material that contains titanium.

8. The method of claim 6, wherein said step of depositing a conductive layer is performed such that said conductive layer is approximately 300 angstroms thick.

9. The method of claim 6, wherein said step of depositing a spacer layer is performed with photoresist.

10. The method of claim 6, wherein said subjecting step is performed at a temperature less than 400 degrees centigrade.

11. The method of claim 6, further comprising the step of making the hinge by first depositing a thin conductive hinge layer, patterning and etching said hinge layer, and depositing aluminum by CVD over the patterned hinge layer, until a desired thickness of said hinges is achieved.

12. The method of claim 6, further comprising the step of making the mirrors by first depositing a thin conductive mirror layer, patterning and etching said mirror layer, and depositing aluminum by CVD over the patterned mirror layer, until a desired thickness of said mirrors is achieved.

13. An improved method of fabricating a support post for a digital micro-mirror device, said device having a substrate upon which mirror elements having the following elements are fabricated:

a hinge support post, a hinge extending from said support post, a yoke attached to said hinge, a mirror support post on said yoke, and a mirror mounted on said mirror support post, wherein said hinge is deformable so as to permit said mirror to deflect upon being subjected to an applied force, comprising the steps of;

fabricating the hinge support posts by depositing a conductive layer on the substrate;

depositing a first spacer layer over said conductive layer;

etching vias into said first spacer layer, each via defining an outer surface of a hinge support post, said etching step being performed through said first spacer layer such that each said via is bottomed by said conductive layer;

subjecting said first spacer layer to an aluminum chemical vapor deposition on its surface; and

continuing said exposing step until said vias are filled with aluminum to a desired height;

fabricating the hinges and the yokes; and

fabricating the mirror support posts by depositing a second spacer layer over said yokes;

etching vias into said second spacer layer, each via defining the outer surface of a mirror support post, said etching step being performed through said second spacer layer such that said yoke layer is at the bottom of each said via;

exposing the top of said second spacer layer to an aluminum chemical vapor deposition; and

continuing said exposing step until said vias arc filled with aluminum to a desired height.

14. The method of claim 13, wherein said step of depositing a conductive layer is performed with a material containing titanium.

15. The method of claim 13, wherein said step of depositing a conductive layer is performed such that said conductive layer is approximately 300 angstroms thick.

16. The method of claim 13, wherein said step of depositing a first spacer layer and said step of depositing a second spacer layer are performed with photoresist.

17. The method of claim 13, wherein said subjecting step is performed at a temperature less than 400 degrees centigrade.

18. The method of claim 13, further comprising the step of making the yokes by first depositing a thin conductive yoke layer, patterning and etching said yoke layer, and depositing aluminum by CVD, a desired thickness of said yokes is achieved.

19. The method of claim 13, further comprising the step of making the mirrors by first depositing a thin conductive mirror layer, patterning and etching said mirror layer, and depositing aluminum by CVD, until a desired thickness of said mirrors is achieved.