Design and Optimization of MOS Capacitor based Radiation Sensor for Space Applications

This paper proposes a unique sensor for detecting total ionizing dose (TID) on metal-oxide-semiconductor (MOS) devices. The proposed capacitive radiation sensor is based on commercial 180 nm complementary metal-oxide semiconductor (CMOS) technology. The sensor parameters of 180 nm length (L) and 20 nm oxide thickness (TOX) have been finalized based on simulation and mathematical analysis. Low and high radiation doses ranging from 100 rad to 1 Mrad are used to characterize it. The sensor's sensitivity for 0-10 krad is 20 mV/krad, 10 krad-100 krad is 3.9 mV/krad, and 100 krad-1 Mrad is 0.6 mV/krad when threshold shift is considered into account. Analysis of fixed oxide charge and interface trap charge generation due to ionizing radiation is done. Because interface traps are crucial to device performance, this device is evaluates using traps between 1 E06 cm-3 and 1 E14 cm-3 for realistic performance. Every interface trap exhibits a threshold voltage (VT) shift. Visual technology computer-aided design (TCAD) simulator was used to build, study, and evaluate a capacitive radiation sensor that might be used as a dosimeter for TID monitoring.