Dependence of Radiation Effects in Si02 at 77 K on

The flatband voltage (VFB) shifts induced by irradiation at 77 K and 300 K are measured at 77 K and 300 K on a MOS capacitor with several post-oxidation annealing (POA) temperatures and several oxide thicknesses. For irradiation at 77 K, as compared with irradiation at 300 K, VFS shifts are independent ofPOA temperature, which are measured at 77 K and 300 K. This characteristic is found regardless of total dose, oxide thickness, or gate bias. It shows that low-tempera-ture annealing is useless in fabricating rad-hard devices which operate at 77 K. As a result of these xperiments, we con-clude that the density of hole trap states in the oxide is not influenced by POA temperature. Ionizing radiation leads to a flatband voltage shift in a metal-oxide-semiconductor (MOS) capacitor and degrades the characteristics of MOS devices. It is well known that processing steps strongly affect the radiation tolerance of MOS devices. At room temperature, the POA temperature in addition to the oxide thickness influences radiation damage. According to recent work (1, 2), it was reported that a low-temperature POA and thin oxide reduced th