MEMS Switch Stiction Release via Resonant Voltage Pulses
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Solution Overview
Problem
As semiconductor devices shrink, micro-electromechanical systems (MEMS) face issues with adhesion forces becoming larger than restoring forces, causing devices to undesirably remain in contact with substrates, leading to stiction problems.
Innovation Solution
Applying pulses of voltage to move MEMS switches between high and low adhesion states, utilizing the spring constant and electrostatic forces to facilitate separation, without the need for additional electrodes, by exciting resonant vibrations and measuring resistance to ensure transition to a low adhesion state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If MEMS devices are shrunk to less than a few micrometers, then device size is reduced, but adhesion forces become larger than restoring forces causing stiction
Solution Approach 1:
The patent applies mechanical vibration to the MEMS device to reduce adhesion forces. By vibrating the device at its resonant frequency, the dynamic forces generated during vibration overcome the static adhesion forces between the MEMS structure and substrate, enabling the device to be released from stiction states without requiring additional electrodes or complex release mechanisms.
Solution Approach 2:
The patent employs periodic action through resonant frequency vibration. By applying vibrational energy at the device's natural resonant frequency, the system accumulates vibrational amplitude over time, creating periodic dynamic forces that systematically work to overcome adhesion forces. This periodic energy input is more efficient than continuous non-resonant vibration.
2Reliability
If adhesion forces are increased to improve contact reliability, then contact stability is improved, but device separation becomes difficult requiring higher forces
Solution Approach 1:
The patent uses mechanical vibration at resonant frequency to create dynamic forces that temporarily overcome static adhesion forces during separation. The vibration induces oscillatory motion that reduces the effective contact time and average adhesion force, allowing separation with much lower peak forces than would be required without vibration.
Solution Approach 2:
The patent changes the operational parameters by introducing vibrational frequency and amplitude as control variables. By tuning the vibration to the device's resonant frequency, the system exploits dynamic parameter changes to temporarily reduce adhesion strength during separation operations, while maintaining strong adhesion during normal contact operations.
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
Effectively reduces stiction forces, allowing MEMS devices to be reliably switched between adhesion states, enabling easier operation and maintenance with lower voltage requirements.
Implementation Method 1
electrostatic forces used to pull the MEMS device out of intimate contact with a substrate
Implementation Method 2
the spring restoring force of the MEMS device itself
Implementation Method 3
measuring the resistance through the switch at the second position
Data Source
AI summary
Embodiments disclosed herein generally solve a stiction problem in switching devices by using a series of pulses of force which take the switch from being strongly adhered to a landing electrode to the point where it is only weakly adhered. Once in the low adhesion state, the switch can then be pulled away from contact with a lower force provided by either the spring constant of the switch and/or the electrostatic forces resulting from low voltages applied to nearby electrodes.