SYNCHROTRON X-RAY-IRRADIATION EFFECTS ON THE DEVICE CHARACTERISTICS AND THE RESISTANCE TO HOT-CARRIER DAMAGE OF MOSFETS WITH 4 NM THICK GATE OXIDES

The effects of synchrotron x-ray irradiation on the device characteris tics and hot-carrier resistance of n- and p-channel metal oxide semico nductor field effect transistors (MOSFETs) with 4 nm thick gate oxides are investigated. In p-channel MOSFETs, device characteristics were s ignificantly affected by the xray irradiation but completely recovered after annealing, while the device characteristics in n-channel MOSFET s were not noticeably affected by the irradiation. This difference app ears to be due to a difference in interface-state. generation. In p-ch annel MOSFETs, defects caused by boron-ion: penetration through the ga te oxides may be sensitive to x-ray irradiation, causing the generatio n of many interface states. These interface states are completely elim inated after annealing in hydrogen gas. The effects of irradiation on the resistance to hot-carrier degradation in annealed 4 nm thick gate- oxide MOSFETs were negligible even at an x-ray dose of 6000 mJ/cm(2).