MEMS Shutter Sticking Prevention via Substrate Protrusion

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Solution Overview

Problem

MEMS shutter arrays in optical filtering devices tend to stick to the substrate due to static electricity and moisture, leading to unreliable operation.

Innovation Solution

Incorporating a protrusion on the substrate's wall surface within the shutter opening to prevent sticking, and applying a voltage to maintain the shutter's position without contact with the wall surface, ensuring reliable opening and closing control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a MEMS shutter is fully opened, then light transmission is maximized, but the shutter sticks to the substrate wall surface due to static electricity and moisture

Engineering Contradiction:

Improvelight transmissionVSAvoidshutter operation reliability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

A protrusion is introduced as an intermediary element between the shutter and the substrate wall. This protrusion prevents direct contact between the shutter and the substrate, thereby eliminating the sticking problem caused by static electricity and moisture while allowing full light transmission when the shutter is opened.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a protrusion is added to prevent sticking, then shutter operation reliability is improved, but device complexity increases

Engineering Contradiction:

Improveshutter operation reliabilityVSAvoidsubstrate structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of modifying the entire substrate structure, a localized protrusion is added only at the critical position where the shutter contacts the substrate wall. This localized modification prevents sticking while minimizing the increase in device complexity.

Inventive Principle:

Principle #3Local quality

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 solution enhances the reliability of optical filtering devices by preventing shutter sticking, thereby improving the performance of optical inspection apparatuses, dark field microscopes, and defect inspection systems.

Implementation Method 1

the opened shutter sticks to the wall surface of a shutter opening provided on the Si substrate due to the effects of static electricity and moisture in the atmosphere

Methodology Applied

Scientific EffectStatic electricity: Electrostatics

Implementation Method 2

applying, when the shutter is opened, a predetermined voltage so that the shutter remains stationary in a space of the shutter opening without contacting a wall surface of the shutter opening

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS20240231064A9Optical filtering device, method of controlling optical filtering device, and MEMS shutter

Publication Date: 2024.07.11 HITACHI HIGH TECH CORP

AI summary

Provided is a highly reliable optical filtering device used as a spatial filter for an optical inspection apparatus and configured to prevent a shutter from sticking to a wall surface of a shutter opening. The optical filtering device includes the shutter openable and closeable by voltage control and a substrate having the shutter opening serving as a movable range of the shutter, in which the substrate includes a sticking prevention part configured to prevent the shutter from sticking to the wall surface of the shutter opening when the shutter is opened.