Encapsulated microelectromechanical structure

• US 9,440,845 B2
• Filed: 12/07/2015
• Issued: 09/13/2016
• 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:
  US14/961,760
• Publication Number:
  US 20160167950A1
• Time in Patent Office: 281 Days
• Field of Search: 257/615, 257/616, 257/619, 257/621, 257/684, 257/698, 257/700, 257/777, 257/E23.128, 257/E23.067
• US Class Current: 1/1
• 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 microelectromechanical system (MEMS) device comprising:

a semiconductor layer disposed between first and second substrate layers and having an opening therein;

a MEMS resonator disposed within the opening in the semiconductor layer and encapsulated therein by the first and second substrate layers; and

an electrical contact extending from the opening to an exterior of the MEMS device and formed at least in part by the semiconductor layer and the first substrate layer.

2. The MEMS device of claim 1 wherein the first substrate layer comprises interior and exterior surfaces, the interior surface being disposed adjacent the semiconductor layer, and wherein the electrical contact 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 MEMS device of claim 1 wherein the MEMS resonator is formed at least in part by a semiconductor structure sufficiently freed from the semiconductor layer during device fabrication to enable the MEMS resonator to move relative to the semiconductor layer.

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

5. The MEMS device of claim 1 wherein the MEMS resonator is anchored to at least one of the semiconductor layer, the first substrate layer or the second substrate layer by an anchor structure that permits mechanical motion of the MEMS resonator relative to the semiconductor layer, first substrate layer and second substrate layer.

6. The MEMS device of claim 1 wherein the electrical contact forms a drive contact to impart energy that effects mechanical oscillation of the MEMS resonator.

7. The MEMS device of claim 1 wherein the electrical contact forms a sense contact to sense mechanical oscillation of MEMS resonator.

8. The MEMS device 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 MEMS device of claim 1 wherein the electrical contact is formed by at least one of a portion of the semiconductor layer rendered electrically conductive by impurity doping, or a portion of the first substrate layer rendered electrically conductive by impurity doping.

10. The MEMS device of claim 1 wherein the electrical contact is formed additionally from a metal structure disposed in electrical contact with an impurity-doped portion of first substrate layer.