Support posts for micro-mechanical devices

• US 5,485,304 A
• Filed: 07/29/1994
• Issued: 01/16/1996
• Est. Priority Date: 07/29/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Kaeriyama, Toshiyuki
• Primary Examiner(s): Lerner, Martin
• Assistant Examiner(s): Schuberg, Darren E.
• Application Number:
  US08/283,486
• Time in Patent Office: 536 Days
• Field of Search: 359/213, 359/221, 359/223, 359/224, 359/225, 359/230, 359/846, 359/849, 359/850, 359/855, 359/871, 359/900, 359/245, 359/259, 359/263, 359/267, 359/276, 359/277, 359/291 , 359/318, 359/296, 345/33, 345/48, 345/108
• US Class Current: 359/291
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: Y10S 359/90 Methods

Abstract

An improved support post (16, 23, 25) for micro-mechanical devices (10). A via (34a) that defines the outer surface of the support post (16) is etched into a spacer layer (34). An oxide layer (41) is conformally deposited over the spacer layer (34) and into the via (34a), and then etched back to the top surface of the spacer layer (34), leaving a sidewall ring (23a) on the inner surface of the via (34a). Next, a metal layer (61) is deposited over the spacer layer (34) and into the via (34a) so as to cover the sidewall ring (23a). This metal layer (61) is then etched to form a support post stem (23) inside the via (34a). The spacer layer (34) is removed, leaving the support post stem (23) and a sidewall ring (23a) around the stem (23).

Claims

1. An improved micro-mechanical device of a type having support posts for mechanical elements, wherein the improvement comprises a support post having:

a hollow support post stem, said stem made by depositing a stem material into a via in a spacer layer that is subsequently removed, said hollow support post stem being filled with material from another layer of said micro-mechanical device; and

a sidewall ring around the outer circumference of said stem, said sidewall ring made by depositing an oxide layer over said spacer layer and into said vias prior to the deposition of said stem material and etching back said oxide layer.

2. The device of claim 1, wherein the inner profile of said support post is rounded at the top edge of said via.

3. The device of claim 1, wherein the inner profile of said support post is slightly convex.

4. The device of claim 1, wherein the inner profile of said support post has an angle greater than 90 degrees at the bottom.

5. A digital micro-mirror device, comprising:

a substrate upon which the following elements are fabricated;

at least one address electrode, a support post, a hinge extending from said support post, a mirror attached to said hinge, wherein said mirror is deflectable so as to tilt upon being subjected to an applied force; and

wherein said support post is comprised of a hollow stem and a sidewall ring, both formed by depositing material into a via etched into a spacer layer that is subsequently removed, wherein said hollow stem is filled with a material from another layer of said micro-mirror device.

6. The digital micro-mirror device of claim 5, wherein said sidewall ring is at the outer surface of said support post.

7. The digital micro-mirror device of claim 5, wherein said sidewall ring is formed from an oxide material.

8. The digital micro-mirror device of claim 5, wherein the inner profile of said support post is rounded at the top edge of said via.

9. The digital micro-mirror device of claim 5, wherein the inner profile of said support post is slightly convex.

10. The digital micro-mirror device of claim 5, wherein the inner profile of said support post has an angle greater than 90 degrees at the bottom.