Pointed Stopper Design for MEMS Microphone Adhesion
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Solution Overview
Problem
Conventional stoppers in capacitive MEMS microphones are prone to adhesion between the vibration membrane and the fixed plate due to their shape, which can lead to malfunction when they break during vibration, and existing methods to minimize adhesion probability by reducing the stopper's surface area result in structural weaknesses.
Innovation Solution
A method for manufacturing a semiconductor device with a stopper having a pointed end, achieved by forming a sacrificial layer with a recess and adjusting the thickness and aspect ratio of openings to create a support layer that forms a stopper with a pointed end, enhancing structural integrity and preventing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface area of the stopper is reduced to minimize adhesion probability, then the adhesion probability between vibration membrane and fixed plate decreases, but the stopper becomes structurally weak and prone to breakage
Solution Approach 1:
The stopper is designed with a pointed tip instead of a flat or rounded end, creating a geometric shape that reduces contact area while maintaining structural integrity. The pointed configuration allows the stopper to effectively prevent adhesion between the vibration membrane and fixed plate without requiring large surface area, thus resolving the contradiction between adhesion prevention and structural strength.
2Reliability
If the stopper surface area is minimized to prevent adhesion, then adhesion probability decreases, but manufacturing precision becomes more difficult to achieve
Solution Approach 1:
The pointed tip geometry provides well-defined manufacturing parameters that can be precisely controlled during fabrication. The specific angular and dimensional characteristics of the pointed end allow for consistent reproduction and quality control, making it easier to achieve manufacturing precision compared to other geometries that would provide equivalent adhesion prevention.
Data Source
AI summary
A method for manufacturing a semiconductor device includes providing a semiconductor structure including a first electrode layer, forming a sacrificial layer on the first electrode layer, the sacrificial layer including a recess having a pointed bottom defining a depth, forming a second electrode layer on the sacrificial layer, the second electrode layer including a first opening exposing the recess, and forming a support layer filling the recess, the first opening, and on the second electrode layer. A portion of the support layer filling the recess forms a stopper having a height equal to the depth of the recess. The method also includes forming a second opening extending through the support layer and the second electrode layer and exposing a surface of the sacrificial layer, and removing a portion of the sacrificial layer to form a cavity.