MEMS Bump Structure with Teeth for Adhesion Prevention

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Solution Overview

Problem

Microelectromechanical Systems (MEMS) devices face challenges in preventing movable portions from adhering to substrates or breaking due to collisions, which can lead to mechanical failure and reduced operational lifespan.

Innovation Solution

Incorporating a bump structure with teeth on its surface, which is suspended above the substrate to create a buffer and reduce contact area, thereby preventing adhesion and damage during movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a movable portion is suspended close to the substrate to save space, then device integration is improved, but the movable portion may adhere to the substrate or break due to collision

Engineering Contradiction:

Improvedevice integrationVSAvoidmovable portion durability

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

A bump structure is introduced as an intermediary element between the movable portion and the substrate. The bump includes a body portion and a protruding tip that contacts the movable portion, serving as a mediator to prevent direct contact between the movable portion and substrate, thereby preventing adhesion and collision damage while maintaining compact device integration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The bump structure is positioned in advance to provide cushioning protection before collision occurs. The protruding tip of the bump extends toward the movable portion, creating a buffer zone that absorbs impact energy and prevents the movable portion from directly colliding with the substrate, thereby preventing breakage before it can occur.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Strength

If the movable portion contacts the substrate to prevent breaking, then mechanical strength is improved, but adhesion occurs leading to mechanical failure

Engineering Contradiction:

Improvemechanical strengthVSAvoidadhesion prevention

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The bump structure provides localized support at specific contact points rather than uniform contact across the entire movable portion. The protruding tip of the bump creates a localized contact point that provides mechanical support while minimizing the contact area between the movable portion and substrate, thereby reducing adhesion forces while maintaining necessary mechanical strength.

Inventive Principle:

Principle #3Local quality

3Reliability

If the movable portion is constrained to prevent adhesion, then reliability is improved, but mechanical stress increases leading to potential breakage

Engineering Contradiction:

Improveadhesion preventionVSAvoidmechanical stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The bump structure segments the contact interface into distinct regions: the bump body portion provides structural support while the protruding tip provides the actual contact point with the movable portion. This segmentation allows the constraint function to be distributed, reducing concentrated mechanical stress while maintaining adhesion prevention through the protruding tip.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20180334378A1Microelectromechanical system device and method for manufacturing the same

Publication Date: 2018.11.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A MEMS device includes a first structure including at least one first bump over a surface of the first structure, a second structure including a first side facing the surface of the first bump and a second side opposite to the first side, and a gap between the first structure and the second structure. The first structure and the second structure are configured to move in relation to each other. The first bump includes a plurality of first teeth over a stop surface of the first bump.