MEMS Inertial Sensor Monocrystalline Silicon Shielding

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Solution Overview

Problem

Existing MEMS inertial sensors face limitations due to high stress in polycrystalline silicon materials, leading to reduced reproducibility, sensitivity, and increased costs, as well as non-uniformity in etching technologies affecting sensor performance and production yield.

Innovation Solution

The use of monocrystalline semiconductor materials for forming thicker movable sensitive elements, combined with conductive layers for shielding and interconnecting structures, enhances sensitivity, reliability, and reproducibility, while simplifying the manufacturing process and reducing external interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polycrystalline silicon is used as structural material, then the manufacturing process is simple, but the material has high stress which affects device reproducibility and increases film thickness, limiting sensor size and sensitivity

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoiddevice reproducibility

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the material parameter from polycrystalline silicon to monocrystalline silicon, fundamentally altering the stress characteristics and enabling thinner film structures while maintaining manufacturing feasibility through established semiconductor processing techniques

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If polycrystalline silicon is used, then the manufacturing process is simple, but film thickness increases which limits sensor size and sensitivity

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidmovable element thickness

Core Design Contradiction:

Ease of manufactureVSLength of moving object

Solution Approach 1:

The patent changes the material parameter from polycrystalline silicon to monocrystalline silicon, enabling the movable element thickness to be reduced from several micrometers to sub-micrometer levels while maintaining structural integrity and enabling higher sensor sensitivity

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If etching technology is used to form sensor parts, then the sensor can be fabricated on a single wafer, but the non-uniformity of etching affects sensor performance and production yield

Engineering Contradiction:

Improvefabrication process integrationVSAvoidsensor uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent divides the sensor fabrication into separate deposition and bonding stages, avoiding the need for complex etching processes on a single wafer. Each substrate can be independently processed with high precision deposition, then bonded together, ensuring uniform sensor performance across production batches

Inventive Principle:

Principle #1Segmentation

4Ease of manufacture

If polycrystalline silicon method is used, then the process is simple, but production yield is reduced and cost is increased

Engineering Contradiction:

Improveprocess simplicityVSAvoidproduction yield

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent changes the material parameter from polycrystalline silicon to monocrystalline silicon, which eliminates the high stress and non-uniformity problems that lead to device failure, thereby increasing production yield despite the slightly more complex deposition process

Inventive Principle:

Principle #35Parameter changes

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

This approach improves the sensitivity and reliability of MEMS inertial sensors, increases production yield, and simplifies the manufacturing process, overcoming the limitations of polycrystalline silicon methods and etching non-uniformities.

Implementation Method 1

the at least one conductive layer comprises a shielding layer, and the shielding layer is located between the first base substrate and the first bonding interface

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Implementation Method 2

forming the at least one conductive layer comprises forming one or more of the at least one conductive layer via a deposition process

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS10591508B2MEMS inertial sensor and forming method therefor

Publication Date: 2020.03.17 MEMSEN ELECTRONICS

AI summary

A method for forming an MEMS inertial sensor is provided, comprising: providing a first substrate having a first surface and a second surface, wherein providing the first substrate comprises providing a first base substrate and forming at least one conductive layer; providing a second substrate having a third surface and a fourth surface; bonding the first surface of the first substrate and the third surface of the second substrate together to form a first bonding interface; thinning the first base substrate from the second surface of the first substrate to remove part of the first base substrate; and forming a movable element of the MEMS inertial sensor, wherein the at least one conductive layer comprises a shielding layer, and the shielding layer is located between the first base substrate and the first bonding interface.