Dual-Side Electrode Fabrication for Thin Film Devices

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Solution Overview

Problem

Conventional MEMS techniques for fabricating thin film devices with electrodes on both sides often result in device failure due to physical stress from bending or folding, which can cause metalized structures to crack and become open-circuited.

Innovation Solution

A method of fabricating thin film structures with conductive electrodes on both front and back sides by forming top-side cavities, depositing metal layers, and etching to create defined metal structures, followed by the deposition of dielectric layers, allowing for the exposure of both front and back electrodes without deforming the device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional MEMS techniques are used to fabricate thin film devices with electrodes on both sides, then electrodes can be positioned on opposite sides of the device, but the physical stress from bending or folding causes metalized structures to crack and fail

Engineering Contradiction:

Improveelectrode positioningVSAvoiddevice integrity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention transitions from a planar fabrication approach to a three-dimensional approach by forming cavities that extend through the dielectric layer and depositing metal at different depths. This allows electrodes to be positioned on both front and back sides of the device without requiring bending or folding, thereby maintaining device integrity while achieving dual-sided electrode connectivity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The invention segments the metal deposition process into multiple stages: forming cavities in the dielectric layer, depositing metal to fill cavities partially, and creating defined metal structures with portions exposed on the front side and portions exposed on the back side. This segmentation allows independent optimization of front and back electrodes without mechanical deformation.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the substrate is bent or folded to face two electrodes in opposite directions, then electrodes on opposite sides can be connected, but the metalized structures crack and become open-circuited

Engineering Contradiction:

Improveelectrode connectivityVSAvoidmetalized structure integrity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The invention performs preliminary actions during fabrication by pre-forming cavities and depositing metal in specific patterns before final device assembly. The metal is deposited to fill cavities and create defined structures with portions naturally exposed on both front and back sides, eliminating the need for post-fabrication bending or folding that would compromise metalized structure integrity.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If top-side electrodes are formed on opposite ends of the device, then electrical connections can be made, but the device must be manually bent or folded which leads to failure

Engineering Contradiction:

Improveelectrode formationVSAvoiddevice functionality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The invention moves from a two-dimensional top-side electrode configuration to a three-dimensional configuration where cavities extend through the dielectric layer and metal is deposited to create structures with portions exposed on both front and back sides. This dimensional change allows electrodes to be formed in their final positions during fabrication without requiring manual bending or folding, improving both ease of manufacture and device reliability.

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

This approach enables the integration of conductive electrodes on both sides of thin film devices, preventing the need for bending and reducing the risk of device failure, suitable for applications like neural stimulation and sensing, and allows for the fabrication of high-density, flexible, and durable electrode arrays.

Implementation Method 1

depositing a metal layer on the first dielectric layer so that a portion of the metal layer fills the cavity

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

ion mill-etched metal-on-polymer thin film devices

Methodology Applied

Scientific EffectIon Beam Etching: Ion Beam

Data Source

PatentUS8183111B1Method of fabricating conductive electrodes on the front and backside of a thin film structure

Publication Date: 2012.05.22 LAWRENCE LIVERMORE NAT SECURITY LLC

AI summary

A method of fabricating a thin film device having conductive front and backside electrodes or contacts. Top-side cavities are first formed on a first dielectric layer, followed by the deposition of a metal layer on the first dielectric layer to fill the cavities. Defined metal structures are etched from the metal layer to include the cavity-filled metal, followed by depositing a second dielectric layer over the metal structures. Additional levels of defined metal structures may be formed in a similar manner with vias connecting metal structures between levels. After a final dielectric layer is deposited, a top surface of a metal structure of an uppermost metal layer is exposed through the final dielectric layer to form a front-side electrode, and a bottom surface of a cavity-filled portion of a metal structure of a lowermost metal layer is also exposed through the first dielectric layer to form a back-side electrode.