MEMS Diaphragm Stress Absorption via Segmented Trench Rings

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Solution Overview

Problem

The sensitivity of MEMS structures, such as microphones, is affected by residual stress in the diaphragm, which varies due to fabrication processes and environmental factors, and conventional methods like trench rings are inadequate for effective stress absorption.

Innovation Solution

A MEMS structure with a diaphragm featuring multiple discontinuous trench/ridge rings at the peripheral region and a corrugated central region, utilizing indent or ridge structures to absorb both horizontal and localized stress, improving stress management and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional trench rings are formed at the peripheral region of the diaphragm, then some residual stress is absorbed, but the sensitivity to air pressure is insufficient and stress absorption is inadequate

Engineering Contradiction:

Improvestress absorptionVSAvoidsensitivity to air pressure

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The diaphragm is segmented into multiple functional regions: peripheral region with discontinuous trench rings, intermediate region with corrugated structures, and central region with additional stress-absorbing features. This segmentation allows different regions to handle different types of stress while maintaining overall sensitivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the diaphragm are given different structural qualities: the peripheral region has trench rings for horizontal stress absorption, the intermediate region has corrugated structures for localized stress management, and the central region maintains openness for pressure sensitivity. Each region's structure is optimized for its specific function

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the diaphragm structure is simplified, then manufacturing is easier, but residual stress cannot be effectively absorbed

Engineering Contradiction:

Improvediaphragm fabricationVSAvoidresidual stress absorption

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The discontinuous trench rings and corrugated structures introduce controlled curvatures and three-dimensional features into the diaphragm planar structure. These curved features absorb residual stress through their geometric configuration while being fabricated using standard semiconductor processing techniques

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The stress-absorbing structures (trench rings and corrugated features) are pre-formed during the fabrication process before the diaphragm is fully assembled. This preliminary structuring ensures that stress absorption capability is built-in from the start, eliminating the need for additional post-processing steps

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8464589B2Micro-electromechanical systems (MEMS) structure

Publication Date: 2013.06.18 SOLID STATE SYST

AI summary

A MEMS structure includes a substrate, a structural dielectric layer, and a diaphragm. A structural dielectric layer is disposed over the substrate. The diaphragm is held by the structural dielectric layer at a peripheral end. The diaphragm includes multiple trench/ridge rings at a peripheral region surrounding a central region of the diaphragm. A corrugated structure is located at the central region of the diaphragm, surrounded by the trench/indent rings.