Integrated getter area for wafer level encapsulated microelectromechanical systems

• US 8,372,676 B2
• Filed: 03/17/2011
• Issued: 02/12/2013
• Est. Priority Date: 02/12/2004
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Lutz, Markus, Partridge, Aaron
• Primary Examiner(s): Toledo, Fernando L
• Assistant Examiner(s): Newton, Valerie N
• Application Number:
  US13/050,099
• Publication Number:
  US 20110165718A1
• Time in Patent Office: 698 Days
• Field of Search: None
• US Class Current: 438/50
• CPC Class Codes: B81B 7/0038 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 1/00285 using materials for controlling the level of pressure, contaminants or moisture inside of the package, e.g. getters
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details

Abstract

There are many inventions described and illustrated herein. In one aspect, present invention is directed to a thin film encapsulated MEMS, and technique of fabricating or manufacturing a thin film encapsulated MEMS including an integrated getter area and/or an increased chamber volume, which causes little to no increase in overall dimension(s) from the perspective of the mechanical structure and chamber. The integrated getter area is disposed within the chamber and is capable of (i) “capturing” impurities, atoms and/or molecules that are out-gassed from surrounding materials and/or (ii) reducing and/or minimizing the adverse impact of such impurities, atoms and/or molecules (for example, reducing the probability of adding mass to a resonator which would thereby change the resonator'"'"'s frequency). In this way, the thin film wafer level packaged MEMS of the present invention includes a relatively stable, controlled pressure environment within the chamber to provide, for example, a more stable predetermined, desired and/or selected mechanical damping of the mechanical structure.

Claims

1. A method of manufacturing a microelectromechanical device having a mechanical structure, a periphery area and a fixed electrode that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming the periphery area disposed over the substrate;

forming a plurality of gaps in the periphery area, wherein the plurality of gaps is disposed in the chamber and exposed to the fluid, and wherein the plurality of gaps increase a volume of the chamber; and

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber, wherein the fluid is contained in the chamber after the chamber is sealed;

wherein;

the mechanical structure and the periphery area are formed within a single layer that extends over the substrate; and

the plurality of gaps and the mechanical structure are etched in a same etching process.

2. The method of claim 1, wherein the increase of the volume of the chamber is by at least 10 times a volume without the gaps.

3. A method of manufacturing a microelectromechanical device including a mechanical structure, a periphery area and a fixed electrode that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming the periphery area disposed over the substrate;

forming a plurality of gaps in the periphery area, wherein the plurality of gaps is disposed in the chamber and exposed to the fluid;

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber, wherein the fluid is contained in the chamber after the chamber is sealed;

wherein the mechanical structure and the periphery area are formed within a single layer that extends over the substrate.

4. A method of manufacturing a microelectromechanical device including a mechanical structure, a periphery area and a fixed electrode that are disposed over or in a substrate and in a chamber which is formed, at least in part, by a thin film encapsulation structure, the method comprising:

forming the mechanical structure disposed over the substrate wherein at least a portion of the mechanical structure is disposed in the chamber;

depositing a fluid in the chamber;

forming the periphery area disposed over the substrate;

forming a plurality of gaps in the periphery area, wherein the plurality of gaps is disposed in the chamber and exposed to the fluid;

sealing the chamber by depositing the thin film encapsulation structure over the mechanical structure and the periphery area, to partially define and seal the chamber, wherein the fluid is contained in the chamber after the chamber is sealed;

wherein the plurality of gaps and the mechanical structure are etched in a same etching process.