Simulation Of Total Ionizing Dose Effect Of SOI CMOS Devices And Design Of The Irradiation Hardness Techniques

Research of radiation effects of SOI devices has kept being important to that of itsradiation-hardened technology, especially research of total dose effect, because it has multipleinsulating oxide layer vulnerable to the effects of radiation, which makes total dose effectes of SOIdevices more complex than bulk silicon devices. By systematic research of radiation-hardened SOIdevices developments at home and abroad, total dose effects of SOI devices is simulated in thispaper and its radiation-hardened technology is further researched.According to research and analysis of failure mechanism of total dose radiation, physicalmodel and TCAD simulation of SOI devices, several contents are researched mainly in this paperas follows:First, by investigating and researching the theory of total dose effects of SOI devices, a newnumerical model of total dose effects for TCAD simulation is proposed. On the basis of analysis ofphysical mechanism of total dose effects of SOI MOSFET, some equations which are description ofphysics process of device are established so that the numerical model of total dose effects isdeduced step by step with the method of directly solving equations, finally getting expressions forconcentration of capture charge of hole in the oxide and threshold voltage drift on total dose.During the process of the numerical model deduced, an important parameter Ntwhich isconcentration of hole trap in the oxidation layer is introduced. This parameter determines thesaturation concentration of capture charge of hole, but for itself it is determined only by its process,the properties of its oxide layer and temperature. Centring on Ntparameter, by using the measureddata of0.8μm SOI CMOS with typical process the new model of total dose effectes is numericallyverified. The result shows that the numerical model of total dose effectes is feasible, because in thecondition of process parameters having been given, the deviation of the theoretical calculations andthe measured values of concentration of capture charge of hole is within10%which is allowabledeviation.Second, based on methods of total dose radiation hardness having been presented，according toproper optimization, radiation-hardened device structure with better performance is obtained.Optimal design of three kinds of radiation-hardened structure such as BUSFET structure, H-shapegate structure and annular gate structure is done.Third, on the basis of the new numerical model of total dose effects having been established,total dose effects of PD SOI MOSFET device using0.8μm CMOS with typical process issimulated in TCAD. In the environment of TCAD Sentaurus software,0.8μm and1.6μm device were established. The process of simulation including process simulation of the devices andsimulation of electrical characteristics of the ones and the irradiated ones of total dose effects.Through the analysis of simulation data, the law of relation that electrical characteristics of PD SOIMOSFET device change along with total dose is summarized, providing reference for further designof new device structure of PD SOI MOSFET.