Micromechanical Mirror Device Anti-Stiction Support Structure

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Solution Overview

Problem

Existing micromechanical mirror devices for Fabry-Perot interferometers face challenges in maintaining high parallelism and preventing sticking issues, which affect their spectral tunability and optical performance across a wide wavelength range.

Innovation Solution

The introduction of a support structure with protruding sections acting as anti-stiction bumps, made from electrically insulating materials, which also provides mechanical rigidity and allows for electrical insulation of mirror elements, enabling better mechanical and electrical control of the mirror devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mirror elements are made highly reflective using high-refractive-index materials, then optical performance is improved, but the risk of sticking between mirror elements increases

Engineering Contradiction:
Improveoptical performanceVSAvoidsticking risk
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An electrically insulating intermediate layer is introduced between the high-refractive-index mirror elements. This intermediary layer prevents direct contact and sticking between the mirror elements while maintaining the optical performance provided by the high-refractive-index materials.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

A sacrificial layer is used during manufacturing that can be selectively removed to create spacing between mirror elements. This disposable layer prevents sticking during operation after being removed to define the final cavity geometry.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Stability of the object's composition

If support structures are added to maintain parallelism, then mechanical stability is improved, but device complexity increases

Engineering Contradiction:
ImproveparallelismVSAvoidstructure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The support structure is merged with the electrically insulating layer, combining mechanical support functionality with electrical insulation in a single integrated component, thereby reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The support structure serves multiple functions simultaneously: it maintains the parallelism of mirror elements, provides electrical insulation between high-refractive-index layers, and defines the cavity geometry. This multi-functionality reduces the need for separate components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of manufacture

If mirror elements are bonded to the same substrate, then manufacturing is simplified, but control over individual mirror element positioning is reduced

Engineering Contradiction:
Improvefabrication simplicityVSAvoidpositioning control
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The support structure is segmented into multiple regions with different thicknesses, allowing differential positioning control of mirror elements. This segmentation enables independent adjustment of cavity geometry while maintaining the benefit of bonding to a common substrate.

Inventive Principle:
Principle #1Segmentation

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 design enhances the robustness and optical performance of the mirror devices by preventing sticking, maintaining parallelism, and allowing for spectral tuning, thereby improving the wavelength range and reflectivity of the Fabry-Perot interferometer.

Implementation Method 1

The at least one support structure has at least one section that protrudes from an outer surface of the first and/or the second mirror element. This section thus functions as a stop or as an anti-static friction bump.

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

at least the relevant section of the at least one support structure acting as a stop is made of an electrically insulating material (insulator). This prevents electrodes from welding to the mirror elements during use of the mirror device

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Implementation Method 3

a cavity consisting of two plane-parallel, highly reflective mirrors spaced apart (cavity length) in the optical wavelength range exhibits strong transmission only for wavelengths where the cavity length is an integer multiple of half the wavelength

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 4

A commonly used design of mirror devices in miniaturized interferometers are dielectric layer systems made of alternating layers of high- and low-refractive-index materials, in particular distributed Bragg reflectors (DBRs)

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 5

dielectric layer systems made of alternating layers of high- and low-refractive-index materials

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3746833B1Micromechanical mirror device, mirror system, and method for producing a micromechanical mirror device
Publication Date: 2023.09.27 ROBERT BOSCH GMBH
  • EP3746833B1 patent drawingFigure 1~3
  • EP3746833B1 patent drawingFigure 4~5
  • EP3746833B1 patent drawingFigure 6~7

AI summary

The invention relates to a micromechanical mirror device, a mirror system, and a method for producing a micromechanical mirror device. The mirror device comprises a first mirror element (10), which is flat, and a second mirror element (20), which is flat, wherein: - the first and second mirror elements (10, 20) are arranged substantially plane-parallel; - an intermediate space (40) between the first and second mirror elements (10, 20) has a lower index of refraction than the first and/or the second mirror element (10, 20); - the first and second mirror elements (10, 20) are locally spaced apart from each other by at least one support structure (130); - the at least one support structure (130) overlaps with the first and second mirror elements (10, 20) in an axial direction (A), which is perpendicular to the first and second mirror elements (10, 20); and - the at least one support structure (130) has a material or is formed from a material that is different from a material from which the first and/or the second mirror element (10, 20) is formed.