Improvement of 28HKMG NIO device HCI by implant scheme and sequence optimize doping profile and e-field

Hot-carrier injection (HCI) is a challenging work of every logic device generation. In this paper, there are two kinds of directions to improve NIO HCI based on 28nm HKMG logic process. The first one is the implant scheme optimization. In this paper implant species combination, tilt and twist angles were studied. The second one is different implant sequences which also have significant impact the doping profile and e-field. In this paper, we studied how different IO LDD implant positions (after LDD SPIKE anneal, after SiGe process, and after main spacer process) impacted substrate current and HCI performance. Extensive TCAD simulations and experiments revealed the optimized implant scheme combining with implant sequence can greatly improve substrate current ~46% and HCI life time ~3.4X. The reduced substrate and improved HCI life time are attributed to two mechanisms 1) less junction impact ionization with dopant profile optimization 2) moving impact ionization point away from Si/SiO2 interface.