Sensor and method of use

• US 6,105,428 A
• Filed: 12/10/1998
• Issued: 08/22/2000
• Est. Priority Date: 12/10/1998
• Status: Expired due to Fees

• Current Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Foerstner, Juergen A., Bergstrom, Paul L., Li, Guang X., Schmiesing, John E., Shemansky, Frank A. Jr., Ger, Muh-Ling
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US09/209,116
• Time in Patent Office: 621 Days
• Field of Search: 73/514.32, 73/514.36, 73/514.38, 73/514.21, 73/514.24, 361/280, 361/283.1, 361/283.3
• US Class Current: 73/514.32
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type

Abstract

A sensor has an electrode (120) that is movable along three mutually perpendicular axes (10, 11, 12). The sensor also has stationary over-travel limiting structures that restrict the movement of the electrode (120) along the three axes (10, 11, 12).

Claims

1. A sensor comprising:

a semiconductor substrate with a surface;

a doped silicon anchor overlying and coupled to the surface of the semiconductor substrate and having protrusions;

a doped silicon beam coupled to the doped silicon anchor and having protrusions;

first and second doped silicon electrodes overlying and coupled to the surface of the semiconductor substrate, each of the first and second doped silicon electrodes having a surface substantially perpendicular to the surface of the semiconductor substrate, the surfaces facing towards each other, and each of the surfaces having protrusions extending toward the other surface, the first and second doped silicon electrodes being stationary relative to the semiconductor substrate;

a doped silicon structure overlying and coupled to the surface of the semiconductor substrate and located between the first and second doped silicon electrodes, the doped silicon structure being stationary relative to the semiconductor substrate, the doped silicon structure having a side surface with a recess and having a flap covering a top portion of the recess; and

a third doped silicon electrode coupled to the doped silicon beam, overlying the surface of the semiconductor substrate, and movable relative to the semiconductor substrate, the doped silicon structure, and the first and second doped silicon electrodes in response to an acceleration force, the third doped silicon electrode having a finger extending from a body, the finger located between the first and second doped silicon electrodes and located between the protrusions of the first and second doped silicon electrodes, wherein a distal end of the finger is located in the recess of the doped silicon structure and under the flap of the doped silicon structure, and wherein the protrusions of the doped silicon anchor, the protrusions of the doped silicon beam, the protrusions of the first and second doped silicon electrodes, the doped silicon structure, and the finger limit movement of the third doped silicon electrode along three axes substantially perpendicular to each other wherein first and second ones of the three axes are substantially parallel to the surface of the semiconductor substrate and wherein a third one of the three axes is substantially perpendicular to the surface of the semiconductor substrate.