Semiconductor chip transducer

• US 5,195,371 A
• Filed: 02/14/1990
• Issued: 03/23/1993
• Est. Priority Date: 01/13/1988
• Status: Expired due to Term

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Greiff, Paul
• Primary Examiner(s): Chapman, John E.
• Application Number:
  US07/479,854
• Time in Patent Office: 1,133 Days
• Field of Search: 73/505, 73/517 R, 73/517 AV, 73/514, 73/517 B, 73/DIG. 1, 331/280, 331/283, 357/26
• US Class Current: 73/514.35
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/0888 for indicating angular acceleration
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends

Abstract

A motion transducer fabricated from a semiconductor material by etched exposure and release of a resiliently suspended element. Electrical sensing and/or torquing is applied to the suspended element to produce mass or vibrational sensitivities to provide a transducer for various physical parameters. In the case of a gyroscopic transducer a mass is applied to the element and may be applied in a balanced configuration on either side. The semiconductor element and electrodes may be isolated by the use of buried PN junctions or dielectric layers, and a separately formed insulating dielectric bridge may be used to provide a support link between the suspended element and the remainder of the semiconductor material. A specific crystal orientation is useful in permitting etch control in freeing the suspended element from the remainder of the material. Suspension link stress relief is provided and a waffle construction achieved in the suspended element for use in motional transduction.

Claims

1. A semiconductor chip motion transducer assembly comprising:

a semiconductor transducer element resiliently supported and surrounded by a semiconductor frame;

said semiconductor frame and transducer element being substantially co-planar at a surface plane thereof, said surface plane being the <

100>

crystalline plane surface of the semiconductor material forming said frame and transducer element;

first and second flexures joining said transducer element to said frame to permit relative motion therebetween about an axis passing through said flexures;

said frame and transducer element being monocrystalline, with said frame comprising an etched portion surrounding said transducer element with peripheral walls of said etched portions substantially parallel to plural <

111>

orientation planes of the semiconductor material forming said frame and transducer element, wherein at least one of said frame and said transducer element defining at least one slot substantially adjacent the location at which at least one of said first flexure and said second flexure joins said transducer element to said frame, said at least one slot providing stress relief;

means for inducing relative motion of said transducer element with respect to said frame; and

means for sensing relative motion of said transducer element with respect to said frame, wherein

said means for inducing and said means for sensing each comprises at least one electrode disposed below said surface plane and extending under at least a portion of said transducer element, for providing application of forces to and detection of motion of said transducer element relative to said frame.

2. The assembly of claim 1 wherein said transducer element includes apertures provided to facilitate the etching of said frame under said transducer element, and to prevent etching being stopped under said transducer element at the <

111>

crystal orientation planes.

3. The assembly of claim 1 further including:

a mass supported by said transducer element, and responsive to said means for inducing, to enable relative motion of said transducer element and supported mass with respect to said frame, and wherein said relative motion enables gyroscopic sensitivity by said means for sensing.

4. The assembly of claim 1 further including:

a mass supported by said transducer element, and responsive to said means for inducing, to enable relative motion of said transducer element and supported mass with respect to said frame, and wherein said relative motion enables acceleration sensitivity by said means for sensing.

5. The assembly of claim 1, wherein:

said transducer element includes first and second transducer elements and third and fourth flexures flexibly joining said first and second transducer elements along an axis substantially orthogonal to said axis running through the first and second flexures joining said first transducer element and said frame.

6. The assembly of claim 1 further including a first and second mass applied to first and second opposite surfaces respectively of said transducer element along said axis passing through the first and second flexures joining said transducer element and said frame.