Hybrid MEMS RF Switch Using CMOS Wiring Layers

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Solution Overview

Problem

The existing methods for manufacturing MEMS switches in integrated circuits are costly and require additional processing steps, as they often rely on specialized processes and materials, increasing the overall manufacturing costs and complexity.

Innovation Solution

The method involves forming a forcing electrode from a lower wiring layer and a lower electrode from an upper wiring layer, with a flexible cantilever arm created using existing CMOS wiring levels, eliminating the need for specialized processes by integrating the MEMS switch fabrication into existing wiring layers, and hermetically sealing the structure using a SiN cap layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If specialized processes and materials are used to manufacture MEMS switches, then the isolation performance is improved, but the manufacturing cost and process complexity increase

Engineering Contradiction:

Improveisolation performanceVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines MEMS switch fabrication with existing CMOS wiring layers, merging two separate manufacturing processes into one. The forcing electrode is formed from a lower wiring layer and the lower electrode from an upper wiring layer of the CMOS device, eliminating the need for separate MEMS processing steps while maintaining switch performance

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The existing CMOS wiring layers are given dual functionality: they serve both as interconnect wiring for the CMOS circuit and as electrodes for the MEMS switch. This multi-functional use of the wiring layers eliminates the need for additional specialized MEMS manufacturing processes

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If additional processing steps are added to form MEMS switch after CMOS wiring completion, then the MEMS switch functionality is achieved, but the manufacturing cost increases

Engineering Contradiction:

ImproveMEMS switch functionalityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent merges MEMS switch formation with the CMOS wiring fabrication process. The forcing electrode is created from a lower wiring layer and the lower electrode from an upper wiring layer, both of which are formed during standard CMOS processing, eliminating additional manufacturing steps

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The CMOS wiring layers themselves serve as the MEMS electrodes, eliminating the need for separate electrode fabrication. The existing wiring structure is repurposed to provide the necessary electrical components for the MEMS switch functionality

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If existing wiring layers are utilized to form MEMS electrodes, then the manufacturing cost is reduced, but the switch performance may be compromised

Engineering Contradiction:

Improvemanufacturing costVSAvoidswitch performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by forming a flexible cantilever arm with specific mechanical properties over the wiring layer electrodes. The cantilever is designed with controlled thickness and material composition to provide the necessary flexibility and force for reliable switch operation, while the electrodes themselves use the existing high-quality CMOS wiring materials

Inventive Principle:

Principle #3Local quality

4Ease of operation

If a flexible cantilever arm is formed over the electrodes, then the switch closing mechanism is achieved, but the device complexity increases

Engineering Contradiction:

Improveswitch closing mechanismVSAvoiddevice structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent combines the cantilever arm function with the upper wiring layer structure. The flexible cantilever is formed by depositing material over the lower wiring layer and patterning it to extend toward the upper wiring layer, integrating the actuation mechanism with the existing wiring architecture rather than adding a completely separate component

Inventive Principle:

Principle #5Merging (Combining)

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 reduces manufacturing costs and simplifies the process by utilizing existing wiring layers, resulting in a cost-effective and efficient method for producing MEMS switches with improved integration into existing IC manufacturing processes.

Implementation Method 1

upon application of a voltage to the forcing electrode, the flexible cantilever arm will contact the lower electrode to close the MEMS switch

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS8748207B2Hybrid MEMS RF switch and method of fabricating same

Publication Date: 2014.06.10 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Structures having a hybrid MEMS RF switch and method of fabricating such structures using existing wiring layers of a device is provided. The method of manufacturing a MEMS switch includes forming a forcing electrode from a lower wiring layer of a device and forming a lower electrode from an upper wiring layer of the device. The method further includes forming a flexible cantilever arm over the forcing electrode and the lower electrode such that upon application of a voltage to the forcing electrode, the flexible cantilever arm will contact the lower electrode to close the MEMS switch.