Temperature-compensated MOS dosimeter fully integrated in a high-voltage 0.35 µm CMOS process

Abstract

This article presents the design, fabrication, and characterization of an integrated differential dosimeter based on the mismatch of two identical field oxide MOS transistors (FOXFETs). This dosimeter was fabricated in a high-voltage 0.35μ {m} CMOS process, where the FOXFET and the biasing circuit were integrated in the same chip. The FOXFET as a single device and the whole circuit as an integrated differential sensor were characterized regarding its response to both radiation and temperature. The differential sensor showed low temperature sensitivity, 320 times lower than that of the single FOXFET, while it also showed a reduction in radiation sensitivity only in a factor of 1.6. These results drastically improved the temperature error factor (TEF), calculated to be 23 mrad/°C. Moreover, the bias-controlled cycled measurement technique was successfully implemented by improving the dose range up to 9.4 krad. Finally, the temperature rejection performance was assessed in real-time measurements during exposure to radiation, and the sensitivity of the dosimeter showed no change with temperature.