MEMS Diaphragm with Compressive Stress and Support Post
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Solution Overview
Problem
Micro-electromechanical systems (MEMS)-based acoustic sensors with diaphragms under net compressive stress tend to buckle during operation, as existing technologies prioritize tensile stress to prevent buckling, making it difficult and costly to manufacture diaphragms with tensile stress.
Innovation Solution
A MEMS device with a diaphragm having a net compressive stress, where the diaphragm is constrained and features a post extending from the backplate to limit maximum deflection, allowing for easier and less expensive manufacturing while preventing buckling through an electrostatic field-induced stress gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diaphragm is made with net tensile stress to prevent buckling, then the stability and reliability of the MEMS device is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the stress parameter from tensile to net compressive stress in the diaphragm. This parameter change allows the use of simpler, more cost-effective manufacturing processes (such as standard semiconductor fabrication techniques) while maintaining device functionality through the introduction of a support post that prevents buckling under compressive load
Solution Approach 2:
The patent introduces a support post as an intermediary element between the diaphragm and the substrate. This post acts as a mechanical mediator that provides localized support to prevent buckling of the compressively-stressed diaphragm, enabling the use of compressive stress without sacrificing structural stability
2Ease of manufacture
If a diaphragm with net compressive stress is used to reduce manufacturing cost, then the ease of manufacture is improved, but the diaphragm tends to buckle during operation reducing reliability
Solution Approach 1:
The patent changes the stress parameter from tensile to net compressive stress in the diaphragm. This parameter change allows the use of simpler, more cost-effective manufacturing processes (such as standard semiconductor fabrication techniques) while maintaining device functionality through the introduction of a support post that prevents buckling under compressive load
Solution Approach 2:
The patent introduces a support post as an intermediary element between the diaphragm and the substrate. This post acts as a mechanical mediator that provides localized support to prevent buckling of the compressively-stressed diaphragm, enabling the use of compressive stress without sacrificing structural stability
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 solution enables the production of MEMS devices with diaphragms that can operate without buckling, maintaining sensitivity and reducing manufacturing costs by utilizing a diaphragm with net compressive stress, which is easier to achieve, while the post limits deflection and prevents sticking issues.
Implementation Method 1
allowing for easier and less expensive manufacturing while preventing buckling through an electrostatic field-induced stress gradient
Data Source
AI summary
An implementation of a MEMS device includes a constrained diaphragm comprising a surface, the diaphragm having a net compressive stress; and a backplate comprising a surface facing the surface of the diaphragm, the surface of the backplate having a center, and a post extending from the surface of the backplate, wherein the post is located at or near a center of the surface and limits a maximum deflection of the diaphragm.