Encapsulated microelectromechanical structure

• US 9,758,371 B2
• Filed: 08/19/2016
• Issued: 09/12/2017
• Est. Priority Date: 01/20/2006
• Status: Active Grant

• Current Assignee: SiTime Corporation (Megachips Corporation)
• Original Assignee: SiTime Corporation (Megachips Corporation)
• Inventors: Partridge, Aaron, Lutz, Markus, Gupta, Pavan
• Primary Examiner(s): FOURSON III, GEORGE R
• Application Number:
  US15/242,437
• Publication Number:
  US 20170101310A1
• Time in Patent Office: 389 Days
• Field of Search: 257417, 257684, 257773, 438 52, 438 98
• CPC Class Codes: B81B 2201/0271 Resonators; ultrasonic resonators
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81B 2203/04 Electrodes
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81B 7/0035 for maintaining a controlled atmosphere inside of the chamber containing the MEMS
• CPC Class Codes: B81B 7/0058 for protecting against damages due to external chemical or mechanical influences, e.g. shocks or vibrations
• CPC Class Codes: B81B 7/007 Interconnections between the MEMS and external electrical signals
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 1/00277 for maintaining a controlled atmosphere inside of the cavity containing the MEMS
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: B81C 2201/0171 Doping materials
• CPC Class Codes: B81C 2203/031 Anodic bondings
• CPC Class Codes: B81C 2203/036 Fusion bonding
• CPC Class Codes: B81C 2203/037 Thermal bonding techniques not provided for in B81C2203/035 - B81C2203/036
• CPC Class Codes: B81C 2203/038 Bonding techniques not provided for in B81C2203/031 - B81C2203/037
• CPC Class Codes: H01L 23/051 another lead being formed by a cover plate parallel to the base plate, e.g. sandwich type
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H10N 30/306 Cantilevers

Abstract

A semiconductor layer having an opening and a MEMS resonator formed in the opening is disposed between first and second substrates to encapsulate the MEMS resonator. An electrical contact that extends from the opening to an exterior of the MEMS device is formed at least in part within the semiconductor layer and at least in part within the first substrate.

Claims

1. A method of fabricating a microelectromechanical system (MEMS) device, the method comprising:

forming a MEMS resonator within an opening in a semiconductor layer;

disposing the semiconductor layer between first and second substrate layers such that the MEMS resonator is encapsulated within the opening; and

forming, at least in part within the semiconductor layer and at least in part within the first substrate layer, an electrical contact that extends from the opening to an exterior of the MEMS device.

2. The method of claim 1 wherein the first substrate layer comprises interior and exterior surfaces, the interior surface being disposed adjacent the semiconductor layer, and wherein forming the electrical contact comprises forming an electrical contact that extends at least from the exterior surface of the first substrate layer to a region of the semiconductor layer adjacent the MEMS resonator.

3. The method of claim 1 wherein forming a MEMS resonator within an opening in a semiconductor layer comprises freeing a portion of the semiconductor layer sufficiently from a remainder of the semiconductor layer to enable resonant motion of the freed portion relative to the remainder of the semiconductor layer, the freed portion forming at least part of the MEMS resonator.

4. The method of claim 1 further comprising disposing an insulator layer between the second substrate layer and the semiconductor layer, the semiconductor layer and insulator layer forming a semiconductor-on-insulator (SOI) structure.

5. The method of claim 1 wherein forming the MEMS resonator within the opening comprises forming an anchor structure that anchors the MEMS resonator to at least one of the semiconductor layer, the first substrate layer or the second substrate layer, the anchor structure permitting mechanical motion of the MEMS resonator relative to the semiconductor layer, first substrate layer and second substrate layer.

6. The method of claim 1 wherein forming the electrical contact comprises forming a drive contact that enables energy to be imparted to the MEMS resonator to effect mechanical oscillation thereof.

7. The method of claim 1 wherein forming the electrical contact comprises forming a sense contact that enables mechanical oscillation of MEMS resonator to be sensed.

8. The method of claim 1 wherein the perimeter of the opening in the semiconductor layer and interior surfaces of the first and second substrate layers define, at least in part, surfaces of a sealed chamber in which the MEMS resonator is disposed.

9. The method of claim 1 wherein forming the electrical contact at least in part within the semiconductor layer and at least in part within the first substrate layer comprises at least one of rendering a portion of the semiconductor layer electrically conductive by impurity doping, or rendering a portion of the first substrate layer electrically conductive by impurity doping.

10. The method of claim 1 forming the electrical contact further comprises disposing a metal structure in electrical contact with an impurity-doped portion of first substrate layer.