The purpose of this project is to develop a high sensitivity vacuum gas sensor using Complementary Metal Oxide Silicon (CMOS) micromachining technology.

A CMOS optical micro-radiator vacuum sensor has been designed, tested and calibrated. The package is comprised of a micromachined radiator and a photodetector. The measurement technique for this device involves an automated system.

MEMS technology helps to lower the power consumption of the device and minimizes the characteristic dimension of the system. Monitoring the radiation improves the sensitivity of measurement by several orders of magnitude compared to the conventional technique of measuring the resistance variation. A power-switching scheme has been introduced to increase the pressure measurement range and extend the lifetime of the device.

A three-mode CMOS photodetector has been designed and tested for the purpose of integration of the system. Output of the photodetector is proportional to the sensitive area of the device and varies linearly with the intensity of incident light.

An automated system has been demonstrated for pressure sensing with constant photodetector output. Calibration of the system has been performed by comparison with secondary standards. Experimental results showed a measurement range from 10⁻³ Pa to 10⁵ Pa and relative error is less than 8% compared with secondary standards.

Analytical and numerical modeling packages have been used to obtain the photodetector response with the pressure variation and temperature distribution of the device. Simulation results demonstrated a good agreement with experimental data.