Semiconductive structure useful as a pressure sensor

• US 4,945,769 A
• Filed: 03/06/1989
• Issued: 08/07/1990
• Est. Priority Date: 03/06/1989
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delco Electronics Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Yoder, Douglas J., Sidner, Diane W., Moss, David E.
• Primary Examiner(s): WOODIEL, DONALD
• Application Number:
  US07/319,023
• Time in Patent Office: 519 Days
• Field of Search: 73/727, 73/726, 73/724, 73/721, 73/720, 73/718, 73/DIG. 4, 73/754, 310/338, 29/621.1, 29/25.35, 338/4
• US Class Current: 73/727
• CPC Class Codes: G01L 9/0042 Constructional details associated with semiconductive diaphragm sensors, e.g. etching, or constructional details of non-semiconductive diaphragms details about the integration or bonding of piezoresistor in or on the diaphragm G01L9/0052 and G01L9/0057 respectively
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm

Abstract

A pressure sensor uses a monocrystalline silicon chip that has a diaphragm portion in which strain gages are formed that overlie a buried cavity. The cavity is formed by a single sided semiconductor fabrication process that includes a pair of preferential etching steps and an epitaxial deposition step.

Claims

1. A pressure sensor comprising:

a monocrystalline semiconductive chip including within its bulk a sealed buried cavity whose lateral extent defines a surface of an overlying diaphragm layer which includes an epitaxial moncrystalline portion and which extends to a first surface of the chip;

means forming at least one strain gage in a portion of the diaphragm layer; and

means in said surface surrounding the diaphragm layer for forming circuit elements for interconnection with said strain gage(s).

2. A semiconductive structure comprising:

a monocrystalline silicon chip including within its bulk an enclosed buried cavity whose lateral extent defines a surface of an overlying monocrystalline silicon diaphragm which includes an epitaxial monocrystalline silicon portion sealing the cavity, and which extends to a first surface of the chip;

means forming four piezoresistors in a portion of the diaphragm layer and interconnecting them to form a Wheatstone bridge; and

means in said chip surrounding said diaphragm layer for forming circuit elements for interconnection with the Wheatstone bridge.

3. A semiconductive pressure sensor structure comprising:

a monocrystalline silicon chip including within its bulk an enclosed buried cavity whose lateral extent defines a surface of an overlying silicon diaphragm layer, said diaphragm layer including an epitaxial monocrystalline silicon portion which seals said enclosed cavity, and said diaphragm layer extending to a first surface of the chip;

means forming at least one pressure sensitive device in a portion of the diaphragm layer; and

means in said surface surrounding the diaphragm layer for forming circuit elements for interconnection with the pressure sensitive device.