Support posts for micro-mechanical devices

• US 5,646,768 A
• Filed: 06/07/1995
• Issued: 07/08/1997
• 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): Dzierzynski, Paul M.
• Assistant Examiner(s): Schuberg, Darren E.
• Application Number:
  US08/476,959
• Time in Patent Office: 762 Days
• Field of Search: 359/196, 359/212, 359/223, 359/224, 359/225, 359/290, 359/291, 359/298, 359/299, 359/318, 359/846, 359/871, 359/872
• US Class Current: 359/224.1
• 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 support post stem, said stem made by depositing two layers of a stem material into a via in a spacer layer that is subsequently removed; and

a sidewall ring between said two layers, said sidewall ring made by depositing an oxide layer over said spacer layer and a first of said two layers and into said vias prior to the deposition of a second of said two layers of said stem material and etching back said oxide layer.

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

a support post stem, said stem made by depositing a stem material into a via in a spacer layer that is subsequently removed;

a sidewall ring covering the inner surface of said stem, wherein said sidewall ring is made by depositing an oxide layer after depositing said stem material; and

wherein said stem material is used to form at least one thin, flexible hinge extending from said support post operable to support said micromechanical element.

3. A digital micromirror 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 hinge is deformable so as to permit said mirror to tilt upon being subjected to an applied force; and

wherein said support post is comprised of a stem, a sidewall ring, and a mirror layer all formed by depositing material into a via etched into a spacer layer that is subsequently removed, wherein said sidewall ring is at the inner surface of said support post, surrounded by said stem and underneath said mirror layer, and wherein said stem material is used to form said hinge as a thin, flexible extension from said support post operable to support said mirror.