Semiconductor pressure sensor and manufacturing method therefor
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Solution Overview
Problem
Conventional semiconductor pressure sensors face challenges in accurately detecting minute pressures due to difficulties in forming films on the diaphragm back surface and controlling stress, leading to interference from laminated films and inaccurate pressure detection.
Innovation Solution
A semiconductor pressure sensor design involving a first silicon substrate, a first silicon oxide film, and a second silicon substrate with gauge resistors and electrodes, where the silicon oxide film forms a closed space and adjusts stress to enable accurate pressure detection through a Wheatstone bridge circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the area of the diaphragm is increased and the thickness is reduced to increase detection sensitivity, then the sensitivity to pressure change is improved, but the diaphragm becomes more susceptible to stress deformation from laminated films, reducing measurement accuracy
Solution Approach 1:
The diaphragm structure is divided into a front surface diaphragm and a back surface diaphragm separated by a through-hole. This segmentation allows independent stress control on each surface, enabling the front surface to maintain high sensitivity while the back surface compensates for stress deformation, thus resolving the contradiction between sensitivity and measurement accuracy
Solution Approach 2:
Different regions of the diaphragm are given different properties: the front surface diaphragm is designed for high sensitivity with larger area and thinner thickness, while the back surface diaphragm is optimized for stress compensation. The through-hole region provides localized structural support, creating local quality differences that balance sensitivity and accuracy
2Device complexity
If only a laminated film is provided on the surface of the silicon substrate, then the structure is simple, but the stress of the diaphragm cannot be controlled, causing minute pressure to be buried in stress influence
Solution Approach 1:
The stress control approach transitions from a single-dimensional laminated film on the surface to a three-dimensional structure involving both front and back surface diaphragms separated by a through-hole. This dimensional change enables independent stress management on each surface, allowing minute pressure detection without being buried in stress influence while maintaining reasonable structural complexity
3Measurement precision
If the diaphragm thickness is reduced to increase sensitivity, then the detection sensitivity is improved, but the diaphragm becomes more vulnerable to damage from excessive pressure
Solution Approach 1:
The diaphragm is segmented into front and back surfaces connected through a through-hole, creating a sandwich structure. This segmentation allows the front surface to be thin for sensitivity while the back surface provides structural support for pressure resistance, resolving the contradiction between sensitivity and strength
Solution Approach 2:
The diaphragm structure forms a composite system with front surface diaphragm, back surface diaphragm, and through-hole region working together. This composite structure combines the advantages of thin films (sensitivity) with supported structures (strength), enabling both high detection sensitivity and resistance to excessive pressure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design allows for precise detection of minute pressures by controlling diaphragm bending and stress, enhancing detection sensitivity and accuracy while preventing diaphragm damage.
Implementation Method 1
a gauge resistor provided on a surface layer of a surface of the second silicon substrate opposite to a surface on which the first silicon oxide film is provided at a position overlapping with the closed space in a plan view
Data Source
AI summary
A semiconductor pressure sensor according to the present disclosure includes: a first silicon substrate; a first silicon oxide film provided on the first silicon substrate and forming a closed space together with the first silicon substrate; a second silicon substrate provided on the first silicon oxide film; a gauge resistor provided on a surface layer of a surface of the second silicon substrate opposite to a surface on which the first silicon oxide film is provided at a position overlapping with the closed space in a plan view; a first electrode electrically connected to one end of the gauge resistor; and a second electrode electrically connected to another end of the gauge resistor.