Deuterium pressure dependence of characteristics and hot-carrier reliability of CMOS devices

Deuterium annealing has been widely demonstrated to be an effective way to improve the hot-carrier reliability of MOS devices. In this paper, we present a thorough study of the effect of deuterium pressure on the characteristics and hot-carrier reliability of MOS devices. N-channel submicron MOS transistors were annealed in deuterium with various pressures, temperatures and annealing times. It is found that device reliability initially improves as deuterium pressure is increased. It reaches a maximum and then begins to degrade with further increase of pressure. For the devices after hydrogen anneal, device reliability constantly degrades as the hydrogen pressure increases. It is concluded that the benefit of high pressure deuterium processing on device reliability is attributed to improved deuterium incorporation, while annealing-induced interface trap creation can negate the benefit at extreme high pressure. It is further shown that the processing temperature can be lowered with high pressure while still maintaining the deuteration benefit. This is particularly significant for future CMOS technology that requires a reduced thermal budget.