MEMS Pressure Switch with Piezoelectric Trip Point Adjustment
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Solution Overview
Problem
Existing pressure transducers, particularly capacitance diaphragm pressure gauges, are expensive and space-consuming, making them inadequate for semiconductor processing where multiple small pressure measurements are required, especially in high vacuum environments.
Innovation Solution
A pressure actuated switch with an elastic diaphragm and a piezoelectric assembly that adjusts the gap distance between conductive surfaces, allowing for a programmable trip point and sensitive pressure detection in the range of 1 Torr to 1×10−7 Torr, using a MEMS-based design with a permanently evacuated cavity and a conductive diaphragm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitance diaphragm pressure gauge is used for pressure measurement and switching, then measurement precision and reliability are improved, but device complexity, cost, and space requirements increase
Solution Approach 1:
The patent extracts the essential switching function from the complex capacitance diaphragm pressure gauge by using a simple diaphragm-contact switch mechanism. The diaphragm directly contacts a contact element to open/close an electrical circuit, eliminating the need for capacitance sensing electronics while maintaining pressure detection capability in the 1×10^-6 Torr to 1 Torr range.
Solution Approach 2:
The patent employs a simple, inexpensive diaphragm-contact switch structure that can be easily manufactured and replaced. The basic components (diaphragm, contact element, housing) form a robust, low-cost alternative to expensive capacitance gauges, suitable for applications where the switch can be replaced rather than repaired.
2Measurement precision
If a capacitance diaphragm pressure gauge is used for switching function, then measurement precision is improved, but device size and cost increase
Solution Approach 1:
The patent extracts only the pressure-to-switching function from the capacitance gauge, using a compact diaphragm-contact mechanism that eliminates bulky electronics. The switch comprises a diaphragm, contact element, and minimal housing, achieving pressure-activated switching in a much smaller package suitable for semiconductor processing equipment.
Solution Approach 2:
The patent uses a thin, flexible diaphragm as the primary sensing and actuating element. This thin-film approach enables compact device volume while maintaining the ability to deflect and contact the switch element at precise pressure thresholds, providing accurate pressure switching in a minimal space.
3Volume of moving object
If a simple pressure switch is used, then device size and cost are reduced, but measurement precision and sensitivity deteriorate
Solution Approach 1:
The patent employs a thin, flexible diaphragm that is highly responsive to pressure changes. The diaphragm's elasticity and thin profile enable it to deflect and contact the switch element at very low pressure thresholds (1×10^-6 Torr to 1 Torr), providing sensitive detection despite the simple, compact structure.
Solution Approach 2:
The patent optimizes the diaphragm's physical parameters (thickness, material properties, geometry) to achieve high sensitivity in the specific pressure range of 1×10^-6 Torr to 1 Torr. By carefully selecting and adjusting these parameters, the simple switch structure achieves measurement precision comparable to complex gauges within its targeted operating range.
4Adaptability or versatility
If multiple pressure switches are installed on the same semiconductor processing tool, then measurement versatility is improved, but device space availability decreases
Solution Approach 1:
The patent extracts the core pressure-switching function into a compact, standalone unit that requires minimal mounting space. Each switch is a self-contained component (diaphragm, contact element, housing) that can be independently installed at different locations on semiconductor processing tools, enabling multiple pressure monitoring points without excessive space consumption.
Solution Approach 2:
The patent designs a universal pressure switch that can be deployed in multiple locations and configurations on semiconductor processing equipment. The standardized compact design allows identical units to serve different pressure monitoring functions (chamber pressure, gas flow pressure, etc.), maximizing versatility while minimizing the space required for each individual switch.
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 solution provides a compact, cost-effective, and highly sensitive pressure actuated switch capable of detecting small pressure differences, suitable for semiconductor processing and high vacuum environments, with a reusable design that can adjust its trip point and output signals without damaging contacts.
Implementation Method 1
The controller applies a control signal to the piezoelectric assembly, and in response the piezoelectric assembly shifts the location of the second conductive surface
Implementation Method 2
The diaphragm is elastic. In response to a sufficient pressure, the first conductive surface deflects in a direction toward the second conductive surface
Implementation Method 3
The switch also has a second conductive surface electrically isolated from the first conductive surface and having an evacuated cavity disposed between the first conductive surface and the second conductive surface
Data Source
AI summary
A pressure actuated switch for a pressure control region includes a diaphragm with a first electrically conductive surface and a second conductive surface electrically isolated from the first conductive surface. The switch also includes an evacuated cavity disposed between the first conductive surface and the second conductive surface and includes a piezoelectric assembly on which is mounted the second conductive surface. A controller applies a control signal to the piezoelectric assembly. The piezoelectric assembly in response to the control signal translates the second conductive surface to set a trip point of the switch. The diaphragm is exposed to the pressure of the pressure control region. In response to the pressure applied to the first conductive surface, the first conductive surface deflects in a direction toward the second conductive surface. The first conductive surface communicates with the second conductive surface to produce a signal when the applied pressure is sufficiently large.