Arched MEMS Membrane Structure to Resist Warpage and Collapse
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Solution Overview
Problem
Micro Electro Mechanical System (MEMS) devices with thin membranes face challenges in achieving structural strength and stress resistance while maintaining sensitivity, as they are prone to warpage and collapsing due to their thinness.
Innovation Solution
A MEMS device with an arched opening is formed through multiple etching processes, including a first etching process to create a supporting substrate and a second etching process to form an arched opening in the semiconductor substrate, enhancing mechanical strength and reducing warpage by making the membrane's edge portions thicker and more resistant to stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the membrane is made thinner to increase sensitivity, then sensitivity is improved, but structural strength and stress resistance deteriorate
Solution Approach 1:
The membrane is designed with non-uniform thickness, featuring thicker edge portions and a thinner central region. This local quality variation allows the membrane to maintain high sensitivity in the central sensing area while the thicker edges provide enhanced structural strength and stress resistance, resolving the contradiction between sensitivity and structural integrity
2Measurement precision
If the membrane is made thinner to increase sensitivity, then sensitivity is improved, but stability and resistance to warpage and collapsing deteriorate
Solution Approach 1:
The membrane features localized thickness variation with thicker edges and thinner center, providing stability where needed while maintaining sensitivity in the sensing region
Solution Approach 2:
The membrane incorporates an arched or curved profile rather than being completely flat, with the arch extending vertically from the substrate. This curvature provides structural rigidity and resistance to collapsing while maintaining the thin profile needed for sensitivity in the central region
3Strength
If the membrane edge portions are made thicker to increase structural strength, then structural strength is improved, but manufacturing complexity increases
Solution Approach 1:
The manufacturing process utilizes parameter changes in the etching process, specifically adjusting etching conditions to create the desired thickness profile. The etch depth and duration are controlled to produce thicker edges and thinner center regions, achieving the strength enhancement through process parameter optimization rather than complex multi-step manufacturing
Data Source
AI summary
A method includes bonding a supporting substrate to a semiconductor substrate of a wafer. A bonding layer is between, and is bonded to both of, the supporting substrate and the semiconductor substrate. A first etching process is performed to etch the supporting substrate and to form an opening, which penetrates through the supporting substrate and stops on the bonding layer. The opening has substantially straight edges. The bonding layer is then etched. A second etching process is performed to extend the opening down into the semiconductor substrate. A bottom portion of the opening is curved.