MEMS Sensor Semiconductor Wiring Thermal Stress
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Solution Overview
Problem
Existing MEMS sensors face reliability issues due to stress generation between semiconductor substrates and connection wirings caused by thermal history, especially when using metal wirings with different linear expansion coefficients, leading to output changes and reduced sensor accuracy.
Innovation Solution
The MEMS sensor employs semiconductor wirings with linear expansion coefficients matching those of the silicon substrate, formed as diffusion or polycrystalline silicon wirings, to connect sensor units and pad units, ensuring consistent performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal wirings are used to connect sensor units and pad units, then electrical connectivity is achieved, but thermal stress is generated due to different linear expansion coefficients between metal and semiconductor substrate
Solution Approach 1:
The patent applies homogeneity by using semiconductor material (silicon) for both the substrate and the connection wiring. This ensures that both components have the same linear expansion coefficient, eliminating thermal stress generation during temperature changes. The wiring is formed as a semiconductor wiring layer integrated with the substrate, creating a homogeneous material system that prevents differential expansion.
Solution Approach 2:
The patent changes the material parameter (linear expansion coefficient) of the connection wiring to match that of the semiconductor substrate. By selecting semiconductor material instead of metal, the linear expansion coefficient parameter is adjusted to be equivalent, thereby preventing thermal stress. This parameter matching is achieved through material selection and integration processes.
2Object-generated harmful factors
If semiconductor wirings with matched linear expansion coefficients are used, then thermal stress is suppressed, but manufacturing complexity increases due to diffusion or polycrystalline silicon formation processes
Solution Approach 1:
The patent merges the connection wiring formation process with the existing semiconductor manufacturing工艺流程. The semiconductor wiring is formed using diffusion or polycrystalline silicon processes that are already part of standard MEMS fabrication, integrating the thermal stress solution into the conventional manufacturing flow without adding separate complex steps.
Solution Approach 2:
The semiconductor material inherently provides the matched linear expansion coefficient property, allowing the wiring to self-regulate thermal expansion without requiring additional compensation mechanisms. The material itself serves the dual function of electrical connectivity and thermal stress prevention.
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
This approach suppresses output changes caused by thermal stress, enhances sensor reliability, and improves accuracy by maintaining equivalent expansion coefficients between the substrate and connection wirings, even under varying thermal conditions.
Implementation Method 1
the connection wiring is a semiconductor wiring formed from a semiconductor material having a linear expansion coefficient equivalent to that of the semiconductor substrate
Implementation Method 2
a piezoresistive pressure sensor in which a diaphragm 3 is formed on a substrate 2 and a piezoresistive element is formed as a sensor element 4 on the diaphragm 3. The MEMS sensor 1 is configured to detect pressure by detecting deflection of the diaphragm 3 due to a pressure difference acting on both sides of the diaphragm 3 as a resistance value change of the piezoresistive element
Data Source
AI summary
AMEMS sensor includes a semiconductor substrate, a sensor unit formed on the semiconductor substrate, a pad unit formed on the semiconductor substrate, and a connection wiring formed on the semiconductor substrate and connecting the sensor unit and the pad unit. The connection wiring is a semiconductor wiring formed from a semiconductor material.