Microelectromechanical systems, and devices having thin film encapsulated mechanical structures

• US 7,288,824 B2
• Filed: 12/30/2005
• Issued: 10/30/2007
• Est. Priority Date: 06/04/2003
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Partridge, Aaron, Lutz, Markus, Kronmueller, Silvia
• Primary Examiner(s): Lewis; Monica
• Application Number:
  US11/323,920
• Publication Number:
  US 20060108652A1
• Time in Patent Office: 669 Days
• Field of Search: 257414-420, 257/787, 257/788, 257/790, 257/E29.324
• US Class Current: 257/414
• CPC Class Codes: B81B 2207/015 the micromechanical device and the control or processing electronics being integrated on the same substrate
• CPC Class Codes: B81C 1/00261 Processes for packaging MEMS devices MEMS packages B81B7/0032, packaging of smart-MEMS B81C1/0023
• 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 2201/0176 Chemical vapour Deposition
• CPC Class Codes: B81C 2203/0136 Growing or depositing of a covering layer
• 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

Abstract

There are many inventions described and illustrated herein. In one aspect, the present invention is directed to a MEMS device, and technique of fabricating or manufacturing a MEMS device, having mechanical structures encapsulated in a chamber prior to final packaging. The material that encapsulates the mechanical structures, when deposited, includes one or more of the following attributes: low tensile stress, good step coverage, maintains its integrity when subjected to subsequent processing, does not significantly and/or adversely impact the performance characteristics of the mechanical structures in the chamber (if coated with the material during deposition), and/or facilitates integration with high-performance integrated circuits. In one embodiment, the material that encapsulates the mechanical structures is, for example, silicon (polycrystalline, amorphous or porous, whether doped or undoped), silicon carbide, silicon-germanium, germanium, or gallium-arsenide.

Claims

1. A microelectromechanical device comprising:

a chamber;

a first layer;

a first encapsulation layer comprising a permeable material, wherein first encapsulation layer forms at least a portion of a wall of the chamber;

a micromechanical structure, wherein;

(1) at least a portion of the micromechanical structure is formed in and/or from the first layer, and (2) at least a portion of the micromechanical structure is disposed in the chamber;

a second encapsulation layer, disposed on the first encapsulation layer to seal the chamber, wherein the second encapsulation layer is a semiconductor material and wherein the first and second encapsulation layers are different from the first layer; and

a field region disposed outside and above the chamber, wherein;

the field region includes monocrystalline silicon;

the first encapsulation layer is a semiconductor material;

a first portion of the first encapsulation layer includes monocrystalline silicon and a second portion of the first encapsulation layer includes a porous or amorphous silicon;

the second portion of the first encapsulation layer is a portion of the wall of the chamber;

a portion of the second encapsulation layer that is on the second portion of the first encapsulation layer includes polycrystalline silicon.

2. A microelectromechanical device comprising:

a chamber;

a first layer;

a first encapsulation layer comprising a permeable material, wherein first encapsulation layer forms at least a portion of a wall of the chamber;

a micromechanical structure, wherein;

(1) at least a portion of the micromechanical structure is formed in and/or from the first layer, and (2) at least a portion of the micromechanical structure is disposed in the chamber;

a second encapsulation layer, disposed on the first encapsulation layer to seal the chamber, wherein the second encapsulation layer is a semiconductor material and wherein the first and second encapsulation layers are different from the first layer;

a contact which is at least partially disposed outside the chamber; and

an insulation layer disposed on at least a portion of the second encapsulation layer, wherein the insulation layer includes an opening over the contact and wherein the microelectromechanical device further includes a highly electrically conductive layer that is disposed in the opening and on the contact and on at least a portion of the insulation layer.

3. A microelectromechanical device comprising:

a chamber;

a first layer;

a first encapsulation layer comprising a permeable material, wherein first encapsulation layer forms at least a portion of a wall of the chamber;

a micromechanical structure, wherein;

(1) at least a portion of the micromechanical structure is formed in and/or from the first layer, and (2) at least a portion of the micromechanical structure is disposed in the chamber;

a second encapsulation layer, disposed on the first encapsulation layer to seal the chamber, wherein the second encapsulation layer is a semiconductor material and wherein the first and second encapsulation layers are different from the first layer;

a contact which is at least partially disposed outside the chamber, wherein the contact includes a semiconductor material that is doped with an impurity to increase the electrical conductivity of the contact;

an insulation layer disposed on the second encapsulation layer; and

a third encapsulation layer disposed on the second encapsulation layer, wherein;

the first encapsulation layer includes a plurality of vents formed therein and a porous polycrystalline silicon or amorphous silicon;

the second encapsulation layer is disposed in the plurality of vents to seal the chamber and includes polycrystalline silicon, silicon carbide, silicon/germanium, germanium, and/or gallium arsenide; and

the third encapsulation layer includes an insulating material.

4. A microelectromechanical device comprising:

a chamber;

a first layer;

a first encapsulation layer comprising a permeable material, wherein first encapsulation layer forms at least a portion of a wall of the chamber and includes at least one vent;

a micromechanical structure, wherein;

(1) at least a portion of the micromechanical structure is formed in and/or from the first layer, and (2) at least a portion of the micromechanical structure is disposed in the chamber;

a second encapsulation layer, disposed on the first encapsulation layer to seal the chamber, wherein the second encapsulation layer is a semiconductor material and wherein the first and second encapsulation layers are different from the first layer;

a contact which is at least partially disposed outside the chamber;

an insulation layer disposed on at least the second encapsulation layer that is disposed in and/or on the at least one vent, wherein the insulation layer includes an opening over the contact; and

a highly electrically conductive layer that is disposed in the opening and on;

(i) the contact and (ii) at least a portion of the insulation layer;

wherein the second encapsulation layer includes polycrystalline silicon.