Monocrystalline NEMS Actuator Structure With Reduced Gap Support

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Solution Overview

Problem

Existing nano-electromechanical systems (NEMS) electromechanical actuators face challenges such as incomplete removal of interlayers, large space requirements due to multi-point suspension, and reduced performance due to non-monocrystalline epitaxial silicon membranes, which affect their electromechanical performance and control.

Innovation Solution

A method for manufacturing an electromechanical actuator with a monocrystalline movable electrode, involving a stack of layers with a movable electrode anchored to a stack and a secondary stack, where the movable electrode is formed by etching and encapsulating pads, allowing for a reduced gap and improved electromechanical response by preserving a portion of the interlayer for support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an epitaxial silicon membrane is used for the movable electrode, then the device can be manufactured with suspended membrane structure, but the electromechanical performance is reduced due to non-monocrystalline structure

Engineering Contradiction:

ImprovemanufacturabilityVSAvoidelectromechanical performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The device is divided into two separate stacks: a first stack containing the monocrystalline movable electrode and a second stack containing the fixed electrodes. This segmentation allows the movable electrode to be formed from monocrystalline silicon via wafer bonding while maintaining the suspended membrane structure, thus resolving the contradiction between manufacturability and electromechanical performance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A sacrificial interlayer is introduced as an intermediary element between the monocrystalline movable electrode and the fixed electrodes. This interlayer enables the suspended structure to be formed by selective removal, allowing the movable electrode to be monocrystalline while maintaining the required suspended geometry for electrostatic actuation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Shape

If the interlayer is completely removed to release the movable electrode, then the suspended structure is achieved, but incomplete removal leads to performance degradation

Engineering Contradiction:

Improvesuspended structureVSAvoidinterlayer removal completeness

Core Design Contradiction:

ShapeVSManufacturing precision

Solution Approach 1:

The interlayer is differentially treated: it is completely removed in the region beneath the movable electrode to create the suspended structure, while being preserved in the anchoring region to provide mechanical support. This local differentiation resolves the contradiction between achieving suspended geometry and ensuring complete removal

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The interlayer is designed with different compositions or structures in different regions before removal, allowing selective etching. The sacrificial portion is prepared in advance to be removable while the support portion remains intact, enabling precise control over where the interlayer is removed

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the movable electrode is kept in suspension at multiple points, then the device structure is stable, but the space requirement increases

Engineering Contradiction:

Improvestructural stabilityVSAvoidspace requirement

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The suspension strategy transitions from multiple-point suspension in the planar direction to single-point suspension at the nanoscale, with the gap dimension optimized to 10 nm. This dimensional optimization reduces the overall device footprint while maintaining stability through precise nanoscale gap control rather than multiple suspension points

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 solution results in a nano-electromechanical actuator with enhanced electromechanical response, reliability, and durability due to the monocrystallinity of the movable electrode and reduced gap, enabling better control of bias voltages and flexibility in using various substrates and materials.

Implementation Method 1

the contact position corresponding to a contact between the movable portion of the movable electrode and the fixed contact electrode when a non-zero bias is applied between the movable electrode and the fixed actuation electrode

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS11799396B2Nanometric electromechanical actuator and method of manufacturing the same

Publication Date: 2023.10.24 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for manufacturing an electromechanical actuator includes providing a primary stack of layers comprising a monocrystalline layer, providing a secondary stack of layers, and forming, in the etching layer, at least three pads. The method further includes encapsulating the three pads by a first encapsulation layer, assembling the primary stack of layers with the secondary stack of layers, removing the first substrate, and forming a movable electrode in the monocrystalline layer.