MEMS Pressure Sensor Stress Isolation via Segmentation
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Solution Overview
Problem
MEMS elements in pressure sensors face challenges in accurately detecting external air pressure changes due to external stress influences on the movable portion, leading to inaccurate output voltage readings.
Innovation Solution
The MEMS module design includes a MEMS element with a hollow portion and a movable portion on a shared substrate, where the electronic component is spaced apart from the MEMS element in a direction perpendicular to the thickness of the movable portion, and a stress relaxation material is used to minimize external stress effects, with the manufacturing process involving groove formation, heat treatment, and bonding of semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electronic component is integrated close to the MEMS element on the same substrate, then the device complexity is reduced and manufacturing is simplified, but external stress transmitted to the movable portion causes inaccurate pressure detection
Solution Approach 1:
The substrate is divided into distinct functional regions: a first region housing the MEMS element with its movable portion and hollow portion, and a second region housing the electronic component. This spatial segmentation allows the MEMS element to be isolated from stress generated by the electronic component, preventing stress interference while maintaining integration on the same substrate. The separation ensures that external stress does not transmit to the movable portion, thereby maintaining measurement precision while avoiding increased device complexity.
2Measurement precision
If the movable portion is made thinner to improve pressure sensitivity, then the detection capability is enhanced, but the movable portion becomes more susceptible to external stress and deformation
Solution Approach 1:
By separating the MEMS element into its own dedicated region on the substrate, isolated from the electronic component region, the movable portion can be designed with optimal thinness for pressure sensitivity without being subjected to stress from adjacent electronic components. This regional isolation protects the thin movable portion from external stress while maintaining its enhanced detection capability.
Solution Approach 2:
The substrate acts as an intermediary structure that provides mechanical support and stress isolation. By positioning the MEMS element and electronic component in separate regions of the substrate, the substrate itself serves as a mediator that prevents stress transmission from the electronic component to the sensitive movable portion, allowing the movable portion to remain thin and sensitive while maintaining structural integrity.
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 configuration allows for accurate derivation of external air pressure changes by isolating the MEMS element and electronic component, reducing external stress impacts and enhancing the accuracy of air pressure detection.
Implementation Method 1
performing a heat treatment on the semiconductor layer; and filling the grooves with a part of the semiconductor layer melted by the heat treatment
Data Source
AI summary
A MEMS module includes: a MEMS element provided with a substrate in which a hollow portion is formed, and including a movable portion, which is a part of the substrate, around the hollow portion, the movable portion having a thickness whose shape is changeable by an air pressure difference between an air pressure inside the hollow portion and an air pressure outside the substrate; and an electronic component, to which an output signal of the MEMS element is inputted, formed on the substrate, wherein the electronic component and the MEMS element are spaced apart from each other in a direction perpendicular to a thickness direction of the movable portion.