Temperature coefficient compensated pressure transducer

• US 4,726,232 A
• Filed: 06/02/1986
• Issued: 02/23/1988
• Est. Priority Date: 06/02/1986
• Status: Expired due to Fees

• Current Assignee: Ohmeda Pte Limited
• Original Assignee: Gould, Inc. (Transdigm Group Incorporated)
• Inventors: Koneval, Donald J.
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US06/869,744
• Time in Patent Office: 631 Days
• Field of Search: 73/708, 73/721, 73/727, 73/754, 73/DIG. 4, 338/4, 338/42, 338/3
• US Class Current: 73/708
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

A pressure transducer, which includes a silicon diaphragm with ion-implanted resistors in Wheatstone Bridge configuration and in insulating layer covering the diaphragm, is provided with temperature compensation for differences in thermal expansion coefficients of the layers by depositing a layer of aluminum onto the central portion of the diaphragm.

Claims

1. An integrated circuit pressure transducer comprising:

a diaphragm, said diaphragm being formed of a material having a first thermal expansion coefficient;

measuring means for measuring the displacement of said diaphragm in response to an applied pressure including four piezoresistive resistors disposed on said diaphragm and connected as the elements of a Wheatstone Bridge circuit, said resistors being positioned on each near the edges of said diaphragm;

an insulation layer covering said diaphragm and insulating said diaphragm from the circuit connections of said measuring means, said insulation layer being formed of a second material having a second thermal expansion coefficient; and

a compensation layer on said insulation layer, said compensation layer including a body of material having a third expansion coefficient and being of a volumetric dimension selected to produce a predetermined value of temperature compensation in said transducer, the peripheral edges of said body being displaced laterally inwardly from said resistors.

2. The pressure transducer of claim 1 wherein said diaphragm is formed of silicon.

3. The pressure transducer of claim 2 wherein said insulation layer is formed of silicon dioxide.

4. The pressure transducer of claim 3 wherein said compensation layer is formed of aluminum.

5. The pressure transducer of claim 4 wherein said resistors are ion implanted in said diaphragm.

6. The pressure transducer of claim 1 wherein said compensation layer is positioned on the central portion of said diaphragm.

7. The pressure transducer of claim 6 wherein said compensation layer body is rectangular in shape.

8. The pressure transducer of claim 7 wherein said compensation layer body shape is square.

9. The pressure transducer of claim 1 including a circuit metallization material electrically connecting said resistors and in which said compensation layer is formed of said circuit metallization material.