Micro-electro-mechanical device having low thermal expansion difference

• US 9,944,513 B2
• Filed: 10/23/2013
• Issued: 04/17/2018
• Est. Priority Date: 11/26/2012
• Status: Active Grant

• Current Assignee: PixArt Imaging Incorporated
• Original Assignee: PixArt Imaging Incorporated
• Inventors: Tsai, Ming-Han, Liu, Yu-Chia, Fang, Wei-Leun
• Primary Examiner(s): WILLIAMS, HEZRON
• Assistant Examiner(s): Sinha, Tarun
• Application Number:
  US14/061,698
• Publication Number:
  US 20140144234A1
• Time in Patent Office: 1,637 Days
• Field of Search: 7351432
• CPC Class Codes: B81B 3/0081 Thermal properties

Abstract

The invention provides a micro-electro-mechanical device which is manufactured by a CMOS manufacturing process. The micro-electro-mechanical device includes a stationary unit, a movable unit, and a connecting member. The stationary unit includes a first capacitive sensing region and a fixed structure region. The movable unit includes a second capacitive sensing region and a proof mass, wherein the first capacitive sensing region and the second capacitive sensing region form a capacitor, and the proof mass region consists of a single material. The connecting member is for connecting the movable unit in a way to allow a relative movement of the movable unit with respect to the stationary unit.

Claims

1. A micro-electro-mechanical device, comprising:

a substrate;

a stationary unit connected to the substrate, the stationary unit including a first capacitive sensing region and a fixed structure region;

a movable unit above the substrate, the movable unit including a second capacitive sensing region and a proof mass, the movable unit having a thickness direction which is normal to a bottom surface of the substrate, and a lateral direction which is in parallel to the bottom surface of the substrate, wherein the first capacitive sensing region and the second capacitive sensing region form a capacitor, and the proof mass consists of a single insulating material which occupies more than 50% of the volume of the movable unit, wherein the second capacitive sensing region includes a stacked multiple-metal-layer structure which includes a plurality of metal layers and a plurality of via layers which are respectively located between the neighboring metal layers in the stacked multiple-metal-layer structure at a side of the proof mass in the lateral direction, and the single insulating material forming the proof mass has a top surface and a bottom surface in the thickness direction, wherein the top surface and the bottom surface are exposed to an open space; and

a connecting member for connecting the movable unit while allowing a relative movement of the movable unit with respect to the stationary unit;

wherein from top view, more than 50% of the total area of the movable unit is formed by the single insulating material from top surface through bottom surface, and the single insulating material contacts lateral side surfaces of a plurality of layers of the stacked multiple-metal-layer structure at a saw teeth interface between one side of the single insulating material and the stacked multiple-metal-layer structure, wherein the lateral side surfaces of the layers of the stacked multiple-metal-layer are facing the lateral direction.

2. The micro-electro-mechanical device of claim 1, wherein the proof mass includes a plurality of through holes.

3. The micro-electro-mechanical device of claim 1, wherein the single material consists of silicon dioxide.

4. The micro-electro-mechanical device of claim 1, wherein the fixed structure region consists of a single material.