MEMS structure with graphene component

Patent metadata

Field	Value
Publication number	US-10053358-B2
Application number	US-201615252637-A
Country	US
Kind code	B2
Filing date	Aug 31, 2016
Priority date	Aug 31, 2016
Publication date	Aug 21, 2018
Grant date	Aug 21, 2018

Abstract

A microelectromechanical systems (MEMS) structure includes a substrate, an epitaxial polysilicon cap located above the substrate, a first cavity portion defined between the substrate and the epitaxial polysilicon cap, and a first graphene component having at least one graphene surface immediately adjacent to the first cavity portion.

First claim

The invention claimed is:

1. A method of forming a microelectromechanical systems (MEMS) structure, comprising:
providing a substrate;
forming a first portion of an epitaxial polysilicon cap above the substrate;
forming a first cavity portion above the substrate by vapor release through at least one vent extending through the first portion of the epitaxial polysilicon cap;
converting a silicon carbide portion immediately adjacent to the first cavity portion to graphene using a hydrogen bake; and
sealing the at least one vent with a second portion of the epitaxial polysilicon cap after converting the silicon carbide portion.

2. The method of claim 1 , wherein:
providing the substrate comprises providing a silicon on insulator (SOI) wafer; and
the method further comprises, prior to forming the first portion of the epitaxial polysilicon cap:
trenching the SOI wafer to expose a silicon portion of the SOI wafer; and
conformally depositing the silicon carbide portion on the exposed silicon portion.

3. The method of claim 2 , wherein trenching the SOI wafer comprises:
deep reactive ion etching a trench completely through a silicon layer of the SOI wafer, the method further comprising
filling the trench with a sacrificial oxide portion after conformally depositing the silicon carbide portion, wherein forming the first cavity portion comprises:
using a hydrofluoric acid vapor to expose the silicon carbide portion.

4. The method of claim 3 , wherein:
conformally depositing the silicon carbide portion comprises conformally depositing the silicon carbide portion on a scalloped surface of the exposed silicon portion; and
converting the silicon carbide portion immediately adjacent to the first cavity portion to graphene using the hydrogen bake further comprises converting the silicon carbide portion to a scalloped graphene portion.

5. The method of claim 2 , wherein:
the hydrogen bake is conducted in an epitaxial reactor; and
the second portion of the epitaxial polysilicon cap is deposited in the epitaxial reactor.

6. The method of claim 1 , wherein:
providing the substrate comprises providing a silicon carbide layer on an insulator layer; and
the silicon carbide portion is a portion of the silicon carbide layer.

7. The method of claim 6 , further comprising, prior to forming the first portion of the epitaxial polysilicon cap:
deep reactive ion etching a trench completely through the silicon carbide layer to expose the silicon carbide portion; and
filling the trench with a sacrificial oxide portion, wherein forming the first cavity portion above the substrate by vapor release through the at least one vent extending through the first portion of the epitaxial polysilicon cap further comprises:
using a hydrofluoric acid vapor to re-expose the silicon carbide portion.

8. The method of claim 7 , wherein:
converting the silicon carbide portion immediately adjacent to the first cavity portion to graphene using the hydrogen bake further comprises completely converting the silicon carbide layer to graphene.

9. The method of claim 8 wherein forming the first cavity portion further comprises releasing a segment of the silicon carbide layer.

10. The method of claim 8 , wherein:
the hydrogen bake is conducted in an epitaxial reactor; and
the second portion of the epitaxial polysilicon cap is deposited in the epitaxial reactor.

Assignees

• Bosch Gmbh Robert

Inventors

• Yama Gary
• Yee Seow Yeun
• Laermer Franz
• Samarao Ashwin

Classifications

• B81B2201/0235

  Accelerometers · CPC title

• B81C2201/112

  Depositing an anti-stiction or passivation coating, e.g. on the elastic or moving parts · CPC title

• B81C1/00984

  Methods for avoiding stiction when the device is in use not provided for in groups B81C1/00968 - B81C1/00976 · CPC title

• B81C2203/0136

  Growing or depositing of a covering layer · CPC title

• B81C1/00206

  Processes for functionalising a surface, e.g. provide the surface with specific mechanical, chemical or biological properties · CPC title