MEMS Support Structures for Stress-Resistant Sensing

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Solution Overview

Problem

Microelectromechanical system (MEMS) devices face challenges in providing cost-effective measurement results due to external mechanical stresses that cause parasitic signals and defects in movable structures, leading to inaccurate readings.

Innovation Solution

A MEMS device design featuring a movable structure with a first support structure and a second support structure within a cavity, where the second support structure is attached to the edge of the MEMS structure to mechanically stabilize it, reducing stress sensitivity and enhancing robustness by forming a cavity bounded by the MEMS and first support structures, and a method involving a sacrificial layer deposition and removal process to create these structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a movable MEMS structure is used to sense physical variables, then measurement capability is improved, but susceptibility to external mechanical stresses causing parasitic signals increases

Engineering Contradiction:

Improvemeasurement capabilityVSAvoidstress sensitivity

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The support structure is divided into two distinct parts: a first support structure attached to the substrate and a second support structure attached to the movable MEMS structure. This segmentation allows each support structure to perform specific functions - the first providing stable anchoring while the second provides mechanical support to the movable structure, thereby reducing stress sensitivity while maintaining measurement capability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second support structure acts as an intermediary element between the substrate and the movable MEMS structure. It mechanically couples the movable structure to the support system while isolating it from harmful external stresses, thus reducing parasitic signals without compromising measurement functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the movable MEMS structure is simplified for cost-effective production, then manufacturing cost is reduced, but robustness against defects decreases

Engineering Contradiction:

Improveproduction costVSAvoidrobustness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The second support structure is designed beforehand to provide mechanical support and stabilize the movable MEMS structure. This prior cushioning against potential defects and stresses ensures that even if defects occur during production or operation, the device maintains robustness and reliability without requiring complex additional protective measures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If additional support structures are added to reduce stress sensitivity, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidstructure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The second support structure is strategically positioned only where needed - attached to the edge or corner of the movable MEMS structure rather than covering the entire structure. This localized approach provides stress relief and improves measurement accuracy while minimizing the increase in overall device complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of providing full support across the entire movable structure, the second support structure provides partial support at critical locations (edge or corner). This partial action is sufficient to reduce stress sensitivity and improve measurement accuracy without the complexity of comprehensive support systems.

Inventive Principle:

Principle #16Partial or excessive action

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 design reduces stress sensitivity and increases the robustness of MEMS devices, allowing for more accurate pressure sensing and reduced impact of defects on capacitance, thereby improving measurement reliability and cost-effectiveness.

Implementation Method 1

depositing a sacrificial layer and forming at least one opening in the sacrificial layer... removing the sacrificial layer, wherein a cavity which is bounded by the MEMS structure and the first support structure is formed

Methodology Applied

Scientific EffectSacrificial layer deposition and removal:

Implementation Method 2

depositing a first material in the at least one opening in the sacrificial layer and depositing a second material over the sacrificial layer... the material which is deposited in the least one opening forms a second support structure

Methodology Applied

Scientific EffectMaterial deposition: Deposition (physical)

Data Source

PatentUS12195325B2MEMS devices with support structures and associated production methods

Publication Date: 2025.01.14 INFINEON TECHNOLOGIES AG

AI summary

A microelectromechanical system (MEMS) device contains a movable MEMS structure, a first support structure in which an edge of the MEMS structure is attached, a cavity which is bounded by the MEMS structure and the first support structure, and a second support structure which is attached in the cavity and at the edge of the MEMS structure and is configured so as to support the edge of the MEMS structure mechanically.