Spring Pillar MEMS Membrane for Sensitivity and Load Robustness

Solution Overview

Problem

MEMS membrane structures face challenges in achieving optimal stiffness control for improved performance and reliability, particularly in responding to small pressure changes while withstanding large external loads, leading to design tradeoffs between device size, sensitivity, and robustness.

Innovation Solution

Incorporating a spring pillar or flexible pillar structure that supports the MEMS sensing membrane, allowing for adjustable stiffness based on lateral thickness and spring membrane area, facilitating controlled deformation and enhanced sensitivity without increasing device size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If the MEMS membrane structure is made larger to increase sensing area, then sensitivity to small pressure changes is improved, but robustness to large external loads deteriorates

Engineering Contradiction:

Improvesensing areaVSAvoidrobustness

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating a non-uniform pillar structure with varying cross-sectional areas along its length. The pillar has a larger cross-sectional area at the base for robustness and a smaller cross-sectional area toward the top for flexibility, allowing different regions to serve different functions - the base provides structural support while the upper portions allow membrane deflection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by designing the pillar with a gradient cross-sectional area that transitions from fixed to flexible characteristics. This dynamic structure allows the pillar to behave as rigid as needed at the base and as flexible as needed at the top, adapting its mechanical properties to the local requirements of supporting the membrane while enabling sensing.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the MEMS membrane structure is made smaller to improve robustness, then reliability under external loads is improved, but sensing area is reduced

Engineering Contradiction:

ImproverobustnessVSAvoidsensing area

Core Design Contradiction:

ReliabilityVSArea of moving object

Solution Approach 1:

The patent applies local quality by creating a non-uniform pillar structure with varying cross-sectional areas along its length. The pillar has a larger cross-sectional area at the base for robustness and a smaller cross-sectional area toward the top for flexibility, allowing different regions to serve different functions - the base provides structural support while the upper portions allow membrane deflection.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements dynamics by designing the pillar with a gradient cross-sectional area that transitions from fixed to flexible characteristics. This dynamic structure allows the pillar to behave as rigid as needed at the base and as flexible as needed at the top, adapting its mechanical properties to the local requirements of supporting the membrane while enabling sensing.

Inventive Principle:

Principle #15Dynamics

3Strength

If conventional fixed pillar structures are used to support the MEMS membrane, then structural support is provided, but stiffness control is limited and sensing performance is reduced

Engineering Contradiction:

Improvestructural supportVSAvoidsensing performance

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by systematically varying the cross-sectional area parameter of the pillar along its length. This geometric parameter variation allows precise control of the pillar's stiffness characteristics, enabling optimization of both structural support and sensing performance by adjusting the gradient profile of the cross-sectional area.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamics by designing the pillar with a gradient cross-sectional area that transitions from fixed to flexible characteristics. This dynamic structure allows the pillar to behave as rigid as needed at the base and as flexible as needed at the top, adapting its mechanical properties to the local requirements of supporting the membrane while enabling sensing.

Inventive Principle:

Principle #15Dynamics

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 spring pillar structure enables larger sensing area and robustness to external loads, while maintaining compact device size and sensitivity to small pressure variations, addressing the limitations of fixed pillar solutions.

Implementation Method 1

Incorporating a spring pillar or flexible pillar structure that supports the MEMS sensing membrane, allowing for adjustable stiffness based on lateral thickness and spring membrane area, facilitating controlled deformation

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20250326628A1Membrane connected to pillar with spring characteristics

Publication Date: 2025.10.23 INVENSENSE INC

AI summary

Microelectromechanical systems (MEMS) apparatuses and processes are described that can employ a spring pillar or flexible pillar coupled to a sensing membrane to enhance deformation of the sensing membrane while providing robust MEMS sensors or devices. Described MEMS sensors or devices can comprise an exemplary spring pillar or flexible pillar between the sensing membrane structure and the backplate structure. Exemplary spring pillar or flexible pillar can facilitate adjusting stiffness of the sensing membrane to provide MEMS sensors or devices having large sensing area and compact device size.