Research On Gamma Transient Ionizing Radiation Model Of SOI MOS Transistor

When the silicon based semiconductor circuits are exposed to high energy transient radiation, a large number of non equilibrium electron hole pairs will be generated which result to photocurrent. The photocurrent in the circuit causes the data to flip, signal shift, or even cause the circuit to burn down. So the circuit applied to radiation environment needs to be harden and in order to simulate the transient radiation response of large scale circuit the transient radiation, it is necessary to study the compact model of the device. For the SOI MOS transistor, the existing dose rate radiation model has the following problems:for different manufacturing process the model is not transplantable, in other processes, the peak photocurrent can not be calculated accurately; for different device structure the model is not transplantable, For example, it can not accurately calculate the peak photocurrent of complex gate structure devices; the model contains only MOS devices with no bias voltage at each end, so it can not be used to simulate the circuit under bias voltage.In this work, it based on the problem of the existing SOI MOS transistor dose rate radiation model to go on further studied. The relationship between the parameters of the analytic solution and the peak photocurrent was calculated and analyzed to puts forward an accuracy and small computational complexity PN junction dose rate radiation model. With different parameters the error of the peak photocurrent between model calculation results and TCAD simulation value is less than 5%. According to the model of PN junction with the aid of TCAD simulation, and analysis the relationship between doping, MOS device the size and other factors with the peak photocurrent of each electrode, through the way of sub circuit the dose rate radiation model of SOI MOS transistor off bias voltage was established. In different manufacturing process and for different device structure,the model parameter was adjusted and the correction term was added to the expression so as to improve the portability of the model. Based on the off bias voltage model through the analysis of the influence of the bias voltage on peak photocurrent of each electrode, a method through photocurrent distribution function for dose rate radiation model of SOI MOS transistor in the bias voltage was proposed and lay the foundation for the establishment of the bias voltage model to meet the needs of circuit simulation.The SOI MOS device chip was placed in an intense radiation environment, and test circuit was designed to measure the photocurrent in contrast to the model calculation value. The results showed a good agreement, thus indicating that the model is reliable and can be used for further circuit design of hardening or guide the selection of proper process and device parameters.