Ionising radiation effects on MOSFET drain current

In these last years several works have been devoted to study the radiation effect in CMOS components with ultrathin gate oxide, showing that different types of leakage current can be produced by high-energy ionizing radiation. Radiation Induced Leakage Current (RILC) [1-2], Radiation Soft Breakdown (RSB) [3-5], and Single Event Gate Rupture (SEGR) [6] represent the most important degradation phenomena affecting ultra-thin oxides. Traditionally, oxide Hard Breakdown (and to a less certain degree, Soft Breakdown) marks the end of the MOSFET lifetime [7], [8], [9]. We found that heavy ions can affect the MOSFET characteristics in a new and unexpected way, representing a new challenge to the reliability of CMOS technologies in radiation harsh applications. In this work we used nMOSFETs with different W/L and tox = 2.5nm, irradiated with 65⋅10 I ions/cm. The devices have been supplied by ST Microelectronics, Agrate Brianza, Italy.