EFFECTS OF IRRADIATION TEMPERATURE ON MOS RADIATION RESPONSE

Effects of irradiation and annealing temperature on radiation-induced charge trapping are explored for MOS transistors, Transistors were irr adiated with 10-keV x rays at temperatures from -25 to 100 degrees C a nd annealed at 100 degrees C for times up to 3.6x10(6) s. Transistor d ata were analyzed for the contributions of radiation-induced charge du e to oxide traps, border traps, and interface traps. Increased irradia tion temperature resulted in increased interface-trap and border-trap buildup and decreased oxide-trapped charge buildup during irradiation. Interface-trap buildup immediately following irradiation for transist ors irradiated at 100 degrees C was equivalent to the buildup of inter face traps in transistors irradiated at 27 degrees C and annealed for one week at 100 degrees C (standard rebound test). For the p-channel t ransistors, a one-to-one correlation was observed between the increase In interface-trap charge and the decrease in oxide-trapped charge dur ing irradiation. This may imply a link between increased interface-tra p buildup and the annealing of oxide-trapped charge in these devices. The observed data can be explained in terms of increased hydrogen ion transport rates to the Si/SiO2, interface during elevated temperature irradiations. These results have implications on hardness assurance te sting and potentially may be used to reduce costs associated with rebo und qualification.