Silicon-rich silicon nitrides as etch stops in MEMS manufacture

• US 8,064,124 B2
• Filed: 05/28/2008
• Issued: 11/22/2011
• Est. Priority Date: 01/18/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Zee, Steve, Chung, Wonsuk, Sasagawa, Teruo
• Primary Examiner(s): Choi; William
• Application Number:
  US12/128,469
• Publication Number:
  US 20080226929A1
• Time in Patent Office: 1,273 Days
• Field of Search: 359/197.1, 359/212.1, 359/223.1, 359/290, 359/291
• US Class Current: 359/291
• CPC Class Codes: B81B 2201/047 Optical MEMS not provided for in B81B2201/042 - B81B2201/045
• CPC Class Codes: B81C 1/00801 Avoid alteration of functional structures by etching, e.g. using a passivation layer or an etch stop layer B81C1/00595, B81C1/00468 take precedence
• CPC Class Codes: B81C 2201/014 by depositing an etch stop layer, e.g. silicon nitride, silicon oxide, metal
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

The fabrication of a MEMS device such as an interferometric modulator is improved by employing an etch stop layer between a sacrificial layer and a an electrode. The etch stop may reduce undesirable over-etching of the sacrificial layer and the electrode. The etch stop layer may also serve as a barrier layer, buffer layer, and/or template layer. The etch stop layer may include silicon-rich silicon nitride.

Claims

1. An unreleased interferometric modulator comprising:

an etch stop layer positioned between a sacrificial layer and a metal mirror layer, wherein the metal mirror layer is adapted to be movable upon removal of the sacrificial layer and the etch stop layer is adapted to be substantially completely removed upon exposure to XeF₂ for less than about 10 minutes, wherein the etch stop layer comprises a silicon nitride, and wherein the ratio of silicon to nitrogen in the silicon nitride layer is greater than about 1;

1.

2. The unreleased interferometric modulator of claim 1, wherein the sacrificial layer is also adapted to be substantially completely removed upon the exposure to XeF₂.

3. The unreleased interferometric modulator of claim 1, wherein the sacrificial layer comprises a material selected from the group consisting of molybdenum and amorphous silicon, and wherein the metal mirror layer comprises aluminum.