Active Thermoelectric Vacuum Sensor Based on Frequency Modulation

Abstract

This paper introduces a thermoelectric-type sensor with a built-in heater as an alternative approach to the measurement of vacuum pressure based on frequency modulation. The proposed sensor is fabricated using the TSMC (Taiwan Semiconductor Manufacturing Company, Hsinchu, Taiwan) 0.35 μm complementary metal-oxide-semiconductor-microelectro-mechanical systems (CMOS–MEMS) process with thermocouples positioned central-symmetrically. The proposed frequency modulation technique involves locking the sensor output signal at a given frequency using a phase-lock-loop (PLL) amplifier to increase the signal-to-noise ratio (SNR) and thereby enhance the sensitivity of vacuum measurements. An improved first harmonic signal detection based on asymmetrical applied heating gives a precise measurement. Following calibration, the output voltage is in good agreement with the calibration values, resulting in an error of 0.25% under pressures between 0.1–10 Torr.

Research on a CMOS-MEMS Infrared Sensor with Reduced Graphene Oxide

“…In recent decades, with the development of complementary metal-oxide-semiconductor (CMOS)-MEMS technology, thermopile IR sensors can be very small in size, mass and volume, with low cost, very low power consumption and high sensitivity, and can be manufactured in batches [ 30 , 31 ]. Our research suggests that it will be more practical in thermal IR sensor applications and compatible with standard CMOS processes and more simplified signal processing.…”

A New Macro-Model of Gas Flow and Parameter Extraction for a CMOS-MEMS Vacuum Sensor

“…In the past several decades, numerous vacuum gauges with a drastic reduction of volume have been developed [1,2]. This development was promoted by mature technology in the semiconductor industry and micro-electro-mechanical systems (MEMS) based on the techniques of microfabrication.…”

“…This development was promoted by mature technology in the semiconductor industry and micro-electro-mechanical systems (MEMS) based on the techniques of microfabrication. Among these, CMOS-MEMS, with its batch fabrication techniques, enables vacuum sensing components to be manufactured with increased performance and reliability, combined with the obvious advantages of low consumed power, and reduced physic size, volume, and weight at a relatively low-cost level [2,3]. It is also easily integrated on the same chip with control or processing circuitry by using a commercial semiconductor device process [2][3][4].…”

“…Among these, CMOS-MEMS, with its batch fabrication techniques, enables vacuum sensing components to be manufactured with increased performance and reliability, combined with the obvious advantages of low consumed power, and reduced physic size, volume, and weight at a relatively low-cost level [2,3]. It is also easily integrated on the same chip with control or processing circuitry by using a commercial semiconductor device process [2][3][4]. Among these studies, thermal MEMS elements are widely used as thermal sensors and heating components, especially thermal-type vacuum sensors (Pirani pressure gauge), which can be used for pressure sensing [5][6][7].…”

“…Thermopile vacuum sensors, based on the Seebeck effect, are fully compatible with CMOS processes, thereby enabling high yield production with minimal post-MEMS processing [1][2][3][4][13][14][15][16][17]. Due to the multi-physics of MEMS devices, it is convenient to use a finite element method for modeling and simulation.…”