Semiconductor pressure sensor having strain gauge and circuit portion on semiconductor substrate

• US 6,653,702 B2
• Filed: 05/30/2001
• Issued: 11/25/2003
• Est. Priority Date: 06/13/2000
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Toyoda, Inao, Suzuki, Yasutoshi, Ishio, Seiichiro, Hamamoto, Kazuaki
• Primary Examiner(s): Lee, Eddie
• Assistant Examiner(s): Ortiz, Edgardo
• Application Number:
  US09/866,752
• Publication Number:
  US 20010052628A1
• Time in Patent Office: 909 Days
• Field of Search: 257/419, 257/417, 257/418, 257/420, 257/415, 438/50, 438/51, 438/52, 438/53
• US Class Current: 257/419
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81C 1/00246 Monolithic integration, i.e. micromechanical structure and electronic processing unit are integrated on the same substrate
• CPC Class Codes: B81C 2203/0778 Topology for facilitating the monolithic integration not provided for in B81C2203/0764 - B81C2203/0771
• CPC Class Codes: G01L 9/0054 integral with a semiconducting diaphragm
• CPC Class Codes: G01L 9/06 of piezo-resistive devices
• CPC Class Codes: H01L 21/84 the substrate being other than a semiconductor body, e.g. being an insulating body
• CPC Class Codes: H01L 27/1203 the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688

Abstract

A semiconductor pressure sensor includes a SOI substrate composed of first and second silicon substrates. A diaphragm portion is formed by the first silicon substrate as a bottom of a recess portion formed in the second silicon substrate. Strain gauges are formed on the diaphragm portion, and a circuit portion is formed on the first silicon substrate at a region other than the diaphragm portion. A LOCOS film for isolating the strain gauges from the circuit portion is formed on the first silicon substrate outside the outermost peripheral portion of the diaphragm portion.

Claims

1. A semiconductor pressure sensor comprising:

a semiconductor substrate including a first silicon substrate, a second silicon substrate, and an insulation film interposed between the first silicon substrate and the second silicon substrate, the second silicon substrate having a recess portion;

a diaphragm portion formed by the first silicon substrate as a bottom of the recess portion to be deformed by a pressure;

a strain gauge formed on the diaphragm portion for generating an electric signal in accordance with deformation of the diaphragm portion;

a circuit portion for detecting the electric signal from the strain gauge, formed on the first silicon substrate at a portion other than the diaphragm portion; and

a LOCOS film formed on a main surface of the first silicon substrate opposite to the second silicon substrate, the LOCOS film being located outside an outermost peripheral portion of and separated from a thin-wall portion of the diaphragm portion on the main surface of the first silicon substrate and electrically isolating the strain gauge from the circuit portion;

wherein;

the diaphragm portion and the circuit portion are covered with a protection film formed on the main surface of the first silicon substrate, the protection film including at least two SiN system insulation films and an oxide film between the at least two SiN system insulation films.

2. A semiconductor pressure sensor comprising:

a semiconductor substrate including a first silicon substrate, a second silicon substrate, and an insulation film interposed between the first silicon substrate and the second silicon substrate, the second silicon substrate having a recess portion;

a diaphragm portion formed by the first silicon substrate as a bottom of the recess portion to be deformed by a pressure;

a strain gauge formed on the diaphragm portion for generating an electric signal in accordance with deformation of the diaphragm portion;

a circuit portion for detecting the electric signal from the strain gauge, formed on the first silicon substrate at a portion other than the diaphragm portion, and composed of a plurality of circuit elements isolated from each other by a trench that penetrates the first silicon substrate in a thickness direction to reach the insulation film; and

a protection film formed on the first silicon substrate to cover the diaphragm portion and the circuit portion, and including at least two SiN system insulation films and an oxide film between the at least two SiN system insulation films.