Investigation of gate sidewall spacer optimization from OFF-state leakage current perspective in 3-nm node device

In this paper, the structural and material optimization of gate sidewall spacer in the perspective of OFF-state leakage current was performed in a 3-nm node nanoplate FET (NPFET). Gate-induced drain leakage (GIDL) current, a dominant factor of OFF-state leakage current, and active performance (ON-current, ON/OFF current ratio, and dynamic performance) were co-optimized according to the structural correlation of gate sidewall spacer with other structural components such as gate, source, and drain length. By optimizing the structure for gate and spacer, intrinsic delay was improved by 9.8%, GIDL current was reduced by 78%, and then on/off current ratio (I_ON/I_OFF) was enhanced by 4.2 times. On-current (I_ON) according to contact resistance (R_con) and dynamic performance was analyzed in relation to source/drain (S/D) and spacer. Consequently, the intrinsic delay was improved by 10% and GIDL current reduced by about 92%, which enhanced I_ON/I_OFF by 7.9 times accordingly. Furthermore, by comparing structural relations between gate spacer and S/D spacer, a better structural optimization method was proposed.