Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Physical deformation
Utility Patent
1999-04-06
2001-01-02
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Physical deformation
C257S783000, C257S417000
Utility Patent
active
06169316
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of Japanese Patent Application No. 10-93260, filed on Apr. 6, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor pressure sensor including a sensor chip fixed to a package by adhesive.
2. Description of the Related Art
Conventionally, a semiconductor pressure sensor includes a sensor chip fixed to a package by adhesive. In this constitution, when the adhesive is composed of silicone adhesive or epoxy adhesive, stream is produced by a difference in thermal expansion coefficient between the sensor chip and the package to deteriorate temperature characteristics of the sensor chip.
To solve this problem, JP-A-6-120527 proposes adhesive such as silicone system gel, which has flexibility after adhered, for fixing the sensor chip not to deteriorate the temperature characteristics of the sensor chip; however, in this case, pressure leakage is liable to occur.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problem. An object of the present invention is to provide a semiconductor pressure sensor that includes a sensor chip fixedly accomodated in a package to have desirable temperature characteristics of the sensor chip and not to cause pressure leakage.
According to the present invention, a semiconductor chip is fixed to an inside bottom wall of a package to define a specific space between a side wall thereof and a side wall of the package, and a first adhesive having a first Young's modulus of equal to or less than 1×10
4
Pa is disposed between the semiconductor chip and the inside bottom wall of the package. Further, a second adhesive having a second Young's modulus of equal to or larger than 1×10
6
Pa is disposed in the specific space to contact the semiconductor chip and the package.
As a result, temperature characteristics of the semiconductor chip is improved by the first adhesive, and simultaneously, sealing property between the semiconductor chip and the package is improved by the second adhesive. Therefore, when the semiconductor device is a pressure sensor, pressure leakage does not occur.
Preferably, the second adhesive has the second Young's modulus of less than 4×10
7
Pa so that the second adhesive does not adversely affect the temperature characteristics of the semiconductor chip. A silicone system gel may be used as the first adhesive, and one of a silicone system adhesive and an epoxy system adhesive may be used as the second adhesive to satisfy the relationships of the Young's moduli described above.
REFERENCES:
patent: 5604363 (1997-02-01), Ichihashi
patent: 5721446 (1998-02-01), Kobayashi
patent: 5828116 (1998-10-01), Ao
patent: 5891759 (1999-04-01), Otsuki
patent: 5948991 (1999-09-01), Nomura et al.
patent: 1-301180 (1989-12-01), None
patent: 6-120527 (1994-04-01), None
patent: 8-240498 (1996-09-01), None
patent: 410332505 (1998-12-01), None
patent: 411023396 (1999-01-01), None
Sakai Minekazu
Suzuki Yasutoshi
Clark Sheila V.
Denso Corporation
Pillsbury Madison & Sutro LLP
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