Monolithic micromechanical apparatus with suspended microstructure

• US 5,847,280 A
• Filed: 05/23/1995
• Issued: 12/08/1998
• Est. Priority Date: 08/17/1990
• Status: Expired due to Term

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Brokaw, A. Paul, Sherman, Steven J., Tsang, Robert W. K., Core, Theresa A.
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US08/448,181
• Time in Patent Office: 1,295 Days
• Field of Search: 73/514.18, 73/514.24, 73/514.32, 73/514.38, 361/280, 361/283.1, 361/283.3
• US Class Current: 73/514.32
• CPC Class Codes: B81B 3/001 Structures having a reduced contact area, e.g. with bumps or with a textured surface
• CPC Class Codes: B81C 1/00214 Processes for the simultaneaous manufacturing of a network or an array of similar microstructural devices
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 1/0092 For avoiding stiction during the manufacturing process of the device, e.g. during wet etching
• CPC Class Codes: B81C 2201/112 Depositing an anti-stiction or passivation coating, e.g. on the elastic or moving parts
• CPC Class Codes: B81C 2203/0735 Post-CMOS, i.e. forming the micromechanical structure after the CMOS circuit
• CPC Class Codes: B81C 2203/0742 Interleave, i.e. simultaneously forming the micromechanical structure and the CMOS circuit
• CPC Class Codes: B81C 99/0035 Testing
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/131 with electrostatic counterbalancing means
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

A monolithic capacitance-type microstructure includes a semiconductor substrate, a plurality of posts extending from the surface of the substrate, a bridge suspended from the posts, and an electrically-conductive, substantially stationary element anchored to the substrate. The bridge includes an element that is laterally movable with respect to the surface of the substrate. The substantially stationary element is positioned relative to the laterally movable element such that the laterally movable element and the substantially stationary element form a capacitor. Circuitry may be disposed on the substrate and operationally coupled to the movable element and the substantially stationary element for processing a signal based on a relative positioning of the movable element and the substantially stationary element. A method for fabricating the microstructure and the circuitry is disclosed.

Claims

1. A monolithic sensor comprising:

a semiconductor substrate;

a microstructure disposed above said substrate, said microstructure including a plurality of posts extending from a surface of said substrate and a silicon bridge suspended above said substrate by said posts, said bridge including a central beam and a plurality of generally parallel movable fingers extending transversely from said beam, said movable fingers being movable from a predetermined position relative to said substrate;

a plurality of generally parallel substantially stationary fingers anchored to said substrate, each of said substantially stationary fingers corresponding to one of said movable fingers and positioned adjacent and parallel to said corresponding movable finger such that said movable finger and said corresponding substantially stationary finger form first and second plates of a capacitor; and

circuitry for generating a signal based on movement of said movable fingers from the predetermined position, said circuitry being coupled to the said movable fingers and said substantially stationary fingers.

2. A monolithic sensor as defined in claim 1 wherein said movable fingers are transversely movable with respect to the surface of said substrate.

3. A monolithic micromechanical apparatus comprising:

a semiconductor substrate including a surface;

a microstructure disposed above said substrate, said microstructure including a plurality of posts extending from the surface of said substrate and a bridge suspended from said substrate by said posts, said bridge including a central beam and a plurality of generally parallel movable fingers extending transversely from said beam;

a plurality of generally parallel electrically conductive substantially stationary fingers anchored to said substrate, each of said substantially stationary fingers corresponding to one of said movable fingers and positioned relative to said corresponding movable finger such that said movable finger and said corresponding substantially stationary finger form a capacitor, with movement of said movable fingers relative to said substantially stationary fingers altering the capacitance between each of said movable fingers and said corresponding substantially stationary finger; and

circuitry disposed on said substrate and operationally coupled to said movable fingers and said substantially stationary fingers for processing a signal based on a relative positioning of said movable fingers and said substantially stationary fingers.

4. A monolithic micromechanical apparatus as defined in claim 3 wherein said movable fingers are transversely movable with respect to the surface of said substrate.

5. A monolithic capacitance-type micromechanical device comprising:

a semiconductor substrate including a surface;

a microstructure disposed above said substrate, said microstructure including a plurality of posts extending from the surface of said substrate and a bridge suspended from said substrate by said posts, said bridge including a central beam and a plurality of generally parallel movable fingers extending transversely from said beam; and

a plurality of generally parallel electrically conductive substantially stationary fingers anchored to said substrate, each of said substantially stationary fingers corresponding to one of said movable fingers and positioned relative to said corresponding movable finger such that said movable finger and said corresponding substantially stationary finger form a capacitor.

6. A monolithic capacitance-type micromechanical device as defined in claim 5 wherein said movable fingers are transversely movable with respect to the surface of said substrate.

7. A capacitance-type micromechanical device comprising:

a semiconductor substrate including a surface;

a microstructure disposed above said substrate, said microstructure including a plurality of posts extending from the surface of said substrate and a bridge suspended from said substrate by said posts, said bridge including a central beam and a plurality of generally parallel movable fingers extending transversely from said beam; and

a plurality of generally parallel electrically conductive substantially stationary fingers anchored to said substrate, each of said substantially stationary fingers corresponding to one of said movable fingers and positioned relative to said corresponding movable finger such that said movable finger and said corresponding substantially stationary finger form a capacitor.

8. A capacitance-type micromechanical device as defined in claim 7 wherein said movable fingers are transversely movable with respect to the surface of said substrate.