Pull-Up RF Micro-Machined Switch for Low Voltage Operation
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Solution Overview
Problem
Conventional micro-machined semiconductor switches require high DC voltage for operation and have a short lifespan due to material deformation, relying on the elastic restoring force of cantilevers for signal isolation, which limits their reliability and applicability in communication systems.
Innovation Solution
A micro-machined switch with a pull-up type electrostatic contact pad is manufactured using silicon substrates with silicon oxide or nitride films, metal wiring, dielectric films for electrostatic force generation, and a cover glass plate to achieve stable operation at low DC voltage, with the contact pad being thick and heavy to ensure reliable contact and detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high DC voltage is applied to generate electrostatic force for actuating the cantilever, then the contact reliability is improved, but the device complexity increases due to the need for a separate voltage boosting circuit
Solution Approach 1:
The patent replaces the mechanical elastic restoring force system with an electrostatic field-based system. Instead of relying on the cantilever's elastic force to restore contact, the invention uses electrostatic attraction between the contact pad and electrode to achieve both contact closure and opening, eliminating the need for high voltage boosting circuits and simplifying the overall device architecture.
2Ease of operation
If the cantilever is made thin to reduce actuation voltage, then the ease of operation is improved, but the reliability deteriorates due to material deformation and short usage life
Solution Approach 1:
The patent inverts the conventional pull-down cantilever design to a pull-up contact pad configuration. Instead of the cantilever being pulled down by electrostatic force and restored by elastic force, the contact pad is pulled up by electrostatic attraction to the electrode, with contact opening achieved through electrostatic repulsion or mechanical release, thereby improving reliability while maintaining low operating voltage.
3Reliability
If the contact pad is made thick and heavy to ensure stable operation, then the reliability is improved, but the actuation voltage required increases
Solution Approach 1:
The patent optimizes the contact pad parameters by making it thick and heavy for stability, but compensates by reducing the electrostatic gap distance and optimizing the electrode configuration. This allows the heavier contact pad to be actuated at lower voltages through enhanced electrostatic field strength, resolving the contradiction between stability and energy consumption.
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 switch operates effectively at low DC voltage, ensuring semi-permanent use with minimal deformation and high isolation characteristics, enabling miniaturization and reliability in communication systems without the need for a separate voltage booting circuit.
Implementation Method 1
laminating a dielectric film on said electrode to generate the electrostatic force for driving contact pad
Implementation Method 2
laminating the both surfaces of silicon substrate with silicon oxide or silicon nitride films to prevent the loss of signal to the interior of the silicon substrate
Implementation Method 3
the opening of the circuit can be facilitated by the relatively large weight of the contact pad by composing the contact pad in a thick metal form
Data Source
AI summary
The present invention relates to the manufacture of a semiconductor switch for use in a variety of communication systems, and particularly to the manufacture of a RF micro-machined switch of pull-up type, wherein an electrostatic electrode is used so as to cause the contact pad involved in the operation of the switch to be pulled upward from below.The RF micro-machined switch of pull-up type according to the invention has a high isolation characteristic for shorting and opening the circuit and needs a low driving voltage, so that miniaturization of communication system is possible because a circuit for booting driving voltage is not required within the system. Further, the characteristic of switch is little changed after a long use because the metal composing the contact pad experiences little deformation during operation, whereby the semi-permanent use of switch is possible.The present invention provides a pull-up type RF micro-machined switch, wherein the shorting of the contact pad with the transmission lines is possible with a low DC voltage by altering the conventional pull-down type electrostatic electrode into a pull-up structure and the opening of the circuit is facilitated by the weight of the contact pad by composing the contact pad in a thick metal layer.