Micromechanical Layer Structure Manufacturing with Protective Layers

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Solution Overview

Problem

The manufacturing of micromechanical resonators faces challenges in achieving low power consumption and high quality due to the electrical resistance of RC-elements, which is influenced by the materials used for electrodes and leads, and the process of removing sacrificial layers can contaminate equipment and require costly cleaning and recalibration.

Innovation Solution

The method involves using protective layers made of inert materials like silicon, which are patterned to create openings that allow for the selective removal of sacrificial layers via gas-phase etching, protecting the functional layers and equipment from contamination, and allowing for the use of metal-containing piezoelectric materials to reduce electrical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gas-phase etching methods are used to remove sacrificial layers, then the sacrificial layers can be effectively removed, but the process equipment becomes contaminated and requires costly cleaning and recalibration

Engineering Contradiction:

Improvesacrificial layer removal effectivenessVSAvoidequipment contamination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces a protective layer as an intermediary between the sacrificial layer and the etching environment. This protective layer is selectively removed to expose the sacrificial layer for etching, then restored afterward. The intermediary layer protects the functional layers and equipment from contamination during the etching process, allowing effective sacrificial layer removal without the harmful side effect of equipment contamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Use of energy by moving object

If metal-containing piezoelectric materials are used to reduce electrical resistance, then power consumption decreases and quality increases, but the manufacturing process becomes more complex and costly

Engineering Contradiction:

Improvepower consumptionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by depositing the protective layer before the sacrificial layer, and then performing selective removal and restoration operations. This preliminary setup enables the use of metal-containing piezoelectric materials in the functional layer without compromising the manufacturing process. The protective layer acts as a shield during subsequent processing steps, allowing complex materials to be handled through standardized procedures.

Inventive Principle:

Principle #10Preliminary action

3Object-generated harmful factors

If protective layers are deposited to protect functional layers during etching, then contamination is prevented, but additional manufacturing steps are required

Engineering Contradiction:

Improvecontamination preventionVSAvoidnumber of manufacturing steps

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The protective layer serves multiple functions: it protects the functional layer during deposition, shields against contamination during sacrificial layer removal, and can be selectively removed and restored. This multi-functionality reduces the need for separate protective measures at each stage, making the additional steps more efficient and justifying the increased process complexity through consolidated functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 results in higher-quality resonators with lower power consumption, reduced contamination risks, and cost savings by eliminating the need for complex cleaning and recalibration of equipment, while enabling precise and effective release of functional layers.

Implementation Method 1

Gas-phase etching methods are often used for removing the sacrificial layers

Methodology Applied

Scientific EffectGas-phase etching:

Implementation Method 2

depositing a functional-layer layer structure on the first protective layer

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Implementation Method 3

polycrystalline silicon and silicon oxide are deposited

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS11405010B2Method for manufacturing a micromechanical layer structure

Publication Date: 2022.08.02 ROBERT BOSCH GMBH

AI summary

A method for manufacturing a micromechanical layer structure, including: providing a first protective layer patterned to have at least one opening which is filled with sacrificial layer material; depositing a functional-layer layer structure; producing a first opening in the functional-layer layer structure to at least one opening of the first protective layer, so that in at least one of the layers of the functional-layer layer structure; depositing a second protective layer so that the first opening is filled with material of the second protective layer; patterning the second protective layer and the filled first opening to have a second opening to the first protective layer, the second opening having the same or a lesser width than the first opening; removing sacrificial layer material at least in the opening of the first protective layer; and removing protective layer material at least in the second opening.