Temperature compensated piezoresistive transducer

• US 4,166,269 A
• Filed: 03/06/1978
• Issued: 08/28/1979
• Est. Priority Date: 03/06/1978
• Status: Expired due to Term

• Current Assignee: Signetics Corporation
• Original Assignee: Signetics Corporation
• Inventors: Gray, Paul R., Stephens, Mark L.
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/883,486
• Time in Patent Office: 540 Days
• Field of Search: 338/3, 338/2, 338/5, 338/47, 338/4, 357/26
• US Class Current: 338/3
• CPC Class Codes: G01L 1/18 using properties of piezo-resistive materials, i.e. materials of which the ohmic resistance varies according to changes in magnitude or direction of force applied to the material
• CPC Class Codes: G01L 9/065 with temperature compensating means non electric temperature compensating means G01L19/04

Abstract

A temperature compensated piezoresistive transducer includes a silicon body having a major top surface and an under surface. The body has generally parallel spaced first and second elongate slots formed therein extending through said top and under surfaces to define a center portion between said slots and first and second outer portions at the outward edge of the respective slots. The center portion is adapted to receive pressure to be measured. The body has an additional slot extending through the top and bottom surfaces and extending around the first, second and center portions to define the outer periphery of a transducer membrane with portions of the body remaining to integrally support the membrane. Plural piezoresistive elements having elongate and transverse dimensions are formed on the membrane. The elements are arrayed to receive compressive and tensile stress when pressure is applied.

Claims

1. A temperature compensated piezoresistive transducer comprising,

a semiconductor body having a major top surface and a bottom surface, said body having generally parallel spaced first and second elongate slots formed therein extending through said top and bottom surfaces to define a center portion extending between said elongate slots and first and second outer portions extending from the outward edge respectively of each of said elongate slots, said center portion being adapted to receive pressure to be measured, said body having two additional opposing U-shaped slots extending through said top and bottom surfaces and extending around said first, second and center portions to define the outer periphery of a transducer membrane with portions of said body between said U-shaped slots remaining to integrally support the membrane,

at least four piezoresistive elements having elongate and transverse dimensions formed on said membrane, said piezoresistive elements being arrayed to receive compressive and tensile stress when pressure is applied and being connected as arms of a piezoresistive transducer bridge in which two opposing arms of the bridge are constituted by two of said piezoresistive elements which experience compression when a force is applied to the center portion of said membrane and in which the other two opposing arms of the bridge are constituted by the remaining two of said piezoresistive elements which experience tension when said force is applied to said center portion, all of said four piezoresistive elements having their elongate dimensions parallel to each other.

2. A transducer as in claim 1 wherein said elongate slots are formed along one crystalline axis of said body and said elements'"'"' elongate dimensions are positioned along a second axis at right angles to said one axis.

3. A transducer as in claim 1 wherein said elongate slots are formed along one crystalline axis of said body and said elements'"'"' elongate dimensions are parallel to said one axis.

4. A transducer as in claim 3, wherein a first pair of said piezoresistive elements are positioned on opposite sides of one of said elongate slots near an end portion thereof and a second pair of said piezoresistive elements are positioned on opposite sides of the other one of said elongate slots near an end portion thereof.