MEMS Switch Interconnect Layout for Corrosion-Resistant Signal Paths

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Solution Overview

Problem

Conventional MEMS switch devices fabricated using surface micromachining techniques face issues with unreliable interconnects due to surface corrosion and leakage currents between adjacent interconnects.

Innovation Solution

The MEMS switch device features conductive pathways buried beneath the insulating layer, with conductive vias extending to the surface, and includes a switch beam with a resistive circuit element formed within the insulating layer, using materials like aluminum and tungsten, and is encapsulated with a protective cap to prevent corrosion and mechanical damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional surface micromachining techniques are used to form interconnects on the surface of the substrate, then the manufacturing process is simple and familiar, but the interconnects become unreliable due to surface corrosion and leakage currents

Engineering Contradiction:
Improveinterconnect reliabilityVSAvoidsurface corrosion and leakage currents
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent moves interconnects from the surface (2D) to subsurface (3D) by embedding conductive pathways within the substrate. This dimensional transition protects interconnects from surface corrosion and leakage currents while maintaining electrical connectivity through the substrate structure.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces an insulating layer as an intermediary between the substrate and surface structures. This layer acts as a barrier that prevents harmful surface effects from reaching the conductive pathways, while still allowing electrical connections to be made through controlled vias.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If interconnects are formed on the surface using conventional techniques, then the fabrication process is straightforward, but signal loss occurs due to corrosion and leakage

Engineering Contradiction:
Improvesignal lossVSAvoidsurface corrosion
Core Design Contradiction:
Loss of energyVSObject-affected harmful factors

Solution Approach 1:

By relocating interconnects from surface to subsurface positions, the patent eliminates exposure to corrosive environmental factors that cause signal loss. The embedded pathways maintain stable electrical properties over time and across operating conditions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The insulating layer serves as a protective intermediary that isolates conductive pathways from harmful surface effects. This barrier prevents corrosion-induced signal degradation while allowing the device to operate reliably in various environments.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If conductive pathways are buried beneath the insulating layer, then protection from corrosion is improved, but the fabrication complexity increases

Engineering Contradiction:
Improveinterconnect protectionVSAvoidfabrication complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent performs preliminary actions by forming conductive pathways within the substrate before adding the insulating layer. This sequence simplifies subsequent processing steps and allows for more straightforward integration of surface structures without requiring complex post-fabrication modifications.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2833388B1A MEMS Switch Device and Method of Fabrication
Publication Date: 2023.12.13 ANALOG DEVICES INT UNLTD CO
  • EP2833388B1 patent drawingFigure 1
  • EP2833388B1 patent drawingFigure 2~3
  • EP2833388B1 patent drawingFigure 4

AI summary

A MEMS switch device including: a substrate layer; an insulating layer formed over the substrate layer; and a MEMS switch module having a plurality of contacts formed on the surface of the insulating layer, wherein the insulating layer includes a number of conductive pathways formed within the insulating layer, the conductive pathways being configured to interconnect selected contacts of the MEMS switch module.