Rotation rate sensor

• US 5,438,870 A
• Filed: 12/30/1993
• Issued: 08/08/1995
• Est. Priority Date: 10/13/1990
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Marek, Jiri, Zabler, Erich
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US08/175,595
• Time in Patent Office: 586 Days
• Field of Search: 73/505, 73/510
• US Class Current: 73/504.02
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass

Abstract

A rotation rate sensor has a multi-layer structure including a monocrystalline silicon layer (10) which forms a carrier structure and a polysilicon layer (21), forming a second layer, and which includes a structural element (30) which acts as an oscillatory body. This structural element (30) is supported on the carrier structure (10) by a plurality of support strips (31), and is deflectable (2) perpendicularly to the major surface of the carrier structure (10). Capacitative or piezo-resistive detecting elements are formed from the second layer for detecting Coriolis force deflections (2), perpendicular to the major surface of said carrier (10) of the structural element (30).

Claims

1. Rotation rate sensor with a multi-layer sensor element having first and second layers (10, 21), wherein

said first layer is a generally planar carrier (10) of monocrystalline silicon having a major surface;

said second layer (21) comprises polysilicon and defines at least one structural element (30) which acts as an oscillatory body, being capable of oscillation in at least a first oscillation direction (1) oriented parallel to said major surface of said planar carrier (10),

said structural element (30) is supported on said major surface of said planar carrier (10) by a plurality of support strips (31),

said structural element (30) is deflectable (2) normal to said major surface of said carrier (10); and

further comprising capacitive or piezoresistive detecting means (17, 181;

21,

     182) for detecting Coriolis force deflections (2), perpendicular to said major surface of said carrier (10), of said structural element (30), formed from said second layer.

2. Sensor according to claim 1,

wherein said carrier (10) consists essentially of a material selected from the group consisting of (110)-oriented monocrystalline silicon and (100)-oriented monocrystalline silicon.

3. Sensor according to claim 1, wherein said structural element (21, 30) is a product made by the process of

depositing a polysilicon layer on portions of the surface of said carrier to form an auxiliary layer, and

subsequently underetching the thus-deposited auxiliary layer.

4. Rotation rate sensor with a multi-layer sensor element having first and second layers (10, 21), wherein

said first layer is a generally planar carrier (10) of monocrystalline silicon having a major surface;

a charge carrier diffusion (11) is formed in a portion of said major surface;

said second layer (21) comprises polysilicon and defines at least one structural element (30) which acts as an oscillatory body, being capable of oscillation in at least a first oscillation direction (1) oriented parallel to said major surface of said planar carrier (10), and

said charge carrier diffusion (11) and said oscillatory body define respective plates of a capacitor which serves to measure movement of said oscillatory body (30) in a direction normal to said major surface of said carrier (10).