MEMS structures and methods for forming the same

• US 8,836,055 B2
• Filed: 09/30/2011
• Issued: 09/16/2014
• Est. Priority Date: 09/30/2011
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Pan, Lung Yuan, Chao, Lan-Lin, Tsai, Chia-Shiung
• Primary Examiner(s): REAMES, MATTHEW L
• Application Number:
  US13/250,078
• Publication Number:
  US 20130082338A1
• Time in Patent Office: 1,082 Days
• Field of Search: 257416-420, 257/E29.324
• US Class Current: 257/420
• CPC Class Codes: B81B 2201/0221 Variable capacitors
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• CPC Class Codes: H01G 5/18 due to change in inclination, e.g. by flexing, by spiral wrapping
• CPC Class Codes: H01L 28/60 Electrodes

Abstract

A device includes a micro-electro-mechanical system (MEMS) device, which includes a movable element and a fixed element. The movable element and the fixed element form two capacitor plates of a capacitor, with an air-gap between the movable element and the fixed element acting as a capacitor insulator of the capacitor. At least one of the movable element and the fixed element has a rugged surface.

Claims

1. A device comprising:

a micro-electro-mechanical system (MEMS) device comprising;

a movable element; and

a fixed element, wherein the movable element and the fixed element form two capacitor plates of a capacitor, with an air-gap between the movable element and the fixed element acting as a capacitor insulator of the capacitor, and wherein the fixed element comprises;

a first silicon-containing layer comprising a rugged surface having a root mean square deviation greater than about 10 nm; and

a second silicon-containing layer adjoining the first silicon-containing layer, wherein one of the first silicon-containing layer and the second silicon-containing layer comprises polysilicon, and another one of the first silicon-containing layer and the second silicon-containing layer comprises amorphous silicon, and wherein a first surface of the first silicon-containing layer has a smaller roughness than the rugged surface, with the first surface of the first silicon-containing layer contacting a second surface of the second silicon-containing layer.

2. The device of claim 1, wherein the second silicon-containing layer comprises polysilicon, and wherein the first silicon-containing layer comprises amorphous silicon.

3. The device of claim 1, wherein the second silicon-containing layer comprises amorphous silicon, and wherein the first silicon-containing layer comprises polysilicon.

4. The device of claim 1, wherein the rugged surface comprises bumps, and wherein the bumps do not have repeated patterns.

5. The device of claim 1 further comprising:

a substrate; and

a dielectric layer over and contacting the substrate, wherein the fixed element has a bottom surface contacting a top surface of the dielectric layer.

6. The device of claim 1 further comprising:

a substrate;

a complementary metal-oxide-semiconductor (CMOS) device at a surface of the substrate; and

a plurality of metal layers over the CMOS device and under the MEMS device.