Semiconductor pressure sensor and method of manufacturing same

• US RE34,893 E
• Filed: 03/22/1993
• Issued: 04/04/1995
• Est. Priority Date: 06/08/1988
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Fujii, Tetsuo, Ina, Osamu, Kuroyanagi, Susumu, Gotoh, Yoshitaka
• Primary Examiner(s): Ngo, Ngan V.
• Application Number:
  US08/035,248
• Time in Patent Office: 743 Days
• Field of Search: 257/254, 257/417, 257/418, 257/419, 257/524, 257/619, 257/622, 257/701
• US Class Current: 257/419
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• 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: H01L 27/067 Lateral bipolar transistor in combination with diodes, or capacitors, or resistors
• CPC Class Codes: H01L 27/092 complementary MIS field-effect transistors

Abstract

A semiconductor pressure sensor of this invention is intended to provide a semiconductor pressure sensor having an excellent electrical isolation between the supporting means of the semiconductor pressure sensor and the semiconductor substrate, the semiconductor pressure sensor basically comprising a semiconductor substrate having a first semiconductor region in which at least a semiconductor device is formed, a second semiconductor region and an isolated layer buried between the first and second semiconductor regions, a cavity provided in the second semiconductor region, the opening thereof existing on the main surface of the second semiconductor region and a strain detecting portion consisting of the semiconductor device and provided in the first semiconductor region opposite to the cavity. The semiconductor pressure sensor is featured in that at least one of the outer peripheral side surfaces of the first and the second semiconductor regions is formed inside of the outermost peripheral side surface of the isolation layer.

Claims

1. A semiconductor pressure sensor comprising:

a first semiconductor substrate including therein semiconductor means for electronically processing a pressure;

an isolation layer formed on one surface of said first semiconductor substrate, having a first surface attached to said one surface of said first semiconductor substrate and a second surface opposite said first surface, and having an outer peripheral side surface portion,

a second semiconductor substrate formed on said second surface of said isolation layer, and provided with a portion into which a pressurized medium to be measured is introduced, said second semiconductor substrate being provided with an outer peripheral side surface portion, formed at a position apart from said outer peripheral side surface portion of said isolation layer by a predetermined length sufficient to remove electrical influences which effect said semiconductor means formed in said first semiconductor substrate, said electrical influences being from said outer peripheral side surface portion of said second semiconductor substrate,

a strain, detecting potion formed at a position in said first semiconductor substrate opposite to said pressurized medium introducing portion in said second semiconductor substrate, for detecting a pressure of a pressurized medium to be measured and introduced into said pressurized medium introducing portion and producing an indication to said semiconductor means indicative thereof.

2. A semiconductor pressure sensor according to claim 1, wherein said strain detecting portion is constituted by a piezoresistance layer formed in said first semiconductor substrate, and said semiconductor means is formed between said piezoresistance layer and said outer peripheral side surface portion of said first semiconductor substrate.

3. A semiconductor pressure sensor according to claim 1, wherein a distance between said outer peripheral side surface portion of said isolation layer and said outer peripheral side surface portion of said second semiconductor region is larger than a thickness of said isolation layer.

4. A semiconductor pressure sensor according to claim 3, wherein said distance is obtained by forming the outer peripheral side surface of said isolation layer in a tapered configuration.

5. A semiconductor pressure sensor according to claim 1, wherein said pressurized medium introducing portion is extended directly to a rear part of said strain detecting portion and extends through said second and first semiconductor substrates.

6. A semiconductor pressure sensor according to claim 1, wherein said first semiconductor substrate is made of a single crystal semiconductor.

7. A semiconductor pressure sensor according to claim 1, wherein said peripheral side surface of said second semiconductor substrate is located at least 2 μ

m inside of an outermost part of said peripheral side surface of said isolation layer.

17. A semiconductor pressure sensor according to one of claims 1 to 8, wherein at least one of the outer peripheral side surfaces of said fist and said second semiconductor substrates is located inside of an outermost peripheral side surface of said isolation layer by said predetermined length.

18. A semiconductor pressure sensor according to claim 17, wherein said predetermined length is determined in such a way that a distance between said outer peripheral side surface portion of said first and second semiconductor substrates is a length exceeding a thickness of said isolation layer.

19. A semiconductor pressure sensor according to claim 17, wherein said outer peripheral side surface portion of said isolation layer is formed in a tapered configuration to form said predetermined length.

20. A semiconductor pressure sensor according to claim 17, wherein said outer peripheral side surface portion of any one of said first and second semiconductor substrates is located at least 2 μ

m inside said outermost peripheral side surface portion of said isolation layer.

21. A semiconductor pressure sensor according to claim 17, wherein said isolation layer comprises an impurity region including mobile ions therein and said impurity region thereof is arranged such that it is not in direct contact with the atmosphere introduced into the vicinity of the pressure sensor.

8. A semiconductor pressure sensor comprising:

a first semiconductor substrate having an outer peripheral side surface portion and provided with a portion into which a pressurized medium to be measured is introduced.

an isolation layer formed on one surface of said first semiconductor substrate, having a first surface attached to said one surface of said first semiconductor substrate and a second surface opposite said first surface, and having an outer peripheral side surface portion,

a second semiconductor substrate formed on said second surface of said isolation layer and provided with a semiconductor structure for electrically processing a pressure detection, said second semiconductor substrate being provided with an outer peripheral side surface portion which is formed at a position apart from said outer peripheral side surface portion of said isolation layer by a predetermined length sufficient to remove electrical influences which affect said semiconductor structure formed in said second semiconductor substrate, which influences are through said outer peripheral side surface portion of said second semiconductor substrate and through said outer peripheral side surface portion of said isolation layer, and

a strain detecting portion formed at a position in said second semiconductor substrate opposite to said pressurized medium introduced portion formed in said first semiconductor substrate for detecting a pressure of a pressurized medium to be measured and introduced into said pressurized medium introducing portion and for producing an indication thereof to said semiconductor structure.

9. A semiconductor pressure sensor according to claim 8, wherein said strain detecting portion is constituted by a piezoresistance layer formed in an vicinity of said semiconductor structure formed in said second semiconductor substrate, and said semiconductor structure is formed between said piezoresistance layer and said outer peripheral side surface portion of said second semiconductor substrate.

10. A semiconductor pressure sensor according to claim 9, wherein said outer peripheral side surface portion of said second semiconductor substrate is exposed to the atmosphere, and further comprising an insulating film, on an upper surface of said second semiconductor substrate opposite to the surface on which said isolation layer is formed.

11. A semiconductor pressure sensor according to claim 9, further comprising an isolating film covering said outer peripheral side surface portion of said second semiconductor substrate.

12. A semiconductor pressure sensor according to claim 8, wherein said semiconductor pressure sensor further comprises:

a diaphragm structure formed on said second semiconductor substrate and at a position opposite to said pressurized medium introducing portion, and

wherein said pressurized medium introducing portion is formed by penetrating said first semiconductor substrate, said isolation layer and said second semiconductor substrate, to extend a tip portion thereof directly to a portion on which said diaphragm structure is located, and an inside surface of said pressurized medium introducing portion formed in said second semiconductor is covered with another isolating film, said strain detecting portion being formed on said portion on which said diaphragm structure is located, said diaphragm structure being provided thereon, and said semiconductor structure being formed between a portion on which said pressurized medium introducing portion is formed in said second semiconductor substrate and said outer peripheral side surface portion of said second semiconductor substrate.

22. A semiconductor pressure sensor according to claim 12, further comprising a polycrystalline silicon layer provided on a rear surface of said strain detecting portion and in said pressurized medium introducing device.

13. A semiconductor pressure sensor, directly mounted on a device related to an engine of an automobile, for detecting a pressure of a medium to be measured, used in said device, wherein said pressure sensor comprises:

a housing provided on said device and including a pressurized medium introducing device therein for introducing a pressurized medium to be measured therein;

a first semiconductor substrate having upper and lower surfaces and an outer peripheral side surface portion extending between said upper and lower surfaces, and provided with a pressurized medium introducing portion, wherein said lower surface of said first semiconductor substrate is connected to said pressurized medium introducing device, whereby said pressurized medium introduced by said pressurized medium introducing device is introduced into said pressurized medium introducing portion;

a second semiconductor substrate having upper and lower surfaces and an outer peripheral side surface portion extended between said upper and lower surfaces and provided with a semiconductor structure for electronically processing a pressure detection;

a strain detecting portion formed in a position in said second semiconductor substrate opposite to said pressurized medium introducing portion formed in said first semiconductor substrate, and detecting a pressure of a pressurized medium to be measured and introduced into said pressurized medium introducing portion; and

an isolating layer provided between said upper surface of said first semiconductor substrate and said lower surface of said second semiconductor substrate to serve as an electrical insulator, and having an outer peripheral side surface portion extending between a first surface coupled to said first semiconductor substrate and a second surface coupled to said second semiconductor substrate, wherein each location of the outer peripheral side surface portions of said isolation layer, said first semiconductor substrate and said second semiconductor substrate, is determined respectively so as to remove electrical influences which affect said semiconductor structure formed in said second semiconductor substrate, caused by influences .[.through.]. .Iadd.from .Iaddend.said outer peripheral side surface portion of said .[.second.]. .Iadd.first .Iaddend.semiconductor substrate and through said outer peripheral side surface portion of said isolation layer.

14. A semiconductor pressure sensor according to claim 13, wherein said device with relation to an engine is a surge tank, and said pressurized medium introducing device is a device for introducing a pressurized medium into said surge tank.

15. A semiconductor pressure sensor according to claim 14, wherein said pressurized medium introducing device is provided with means for preventing foreign particles introduced from said surge tank from entering said pressurized medium introducing portion formed in said first semiconductor substrate.

16. A semiconductor pressure sensor according to claim 14, wherein said outer peripheral side surface portion of said .[.second.]. .Iadd.first .Iaddend.semiconductor substrate is formed at a position apart from said outer peripheral side surface portion of said isolation layer by a predetermined length sufficient to remove electrical influences which affect said semiconductor structure formed in said second semiconductor substrate from said outer peripheral side surface portion of said .[.second.]. .Iadd.first .Iaddend.semiconductor substrate through said outer peripheral side surface portion of said isolation layer.