Drain-structure design for reduced band-to-band and band-to-defect tunneling leakage

The author investigates and models gate-induced drain leakage (GIDL) effects over a wide variety of drain structures, including <e1>n </e1>⁺-As/<e1>n</e1>^--P combinations, <e1>n</e1> ^- implant doses (<e1>N</e1>_n-), and spacer lengths (L_s). An analytical model taking account of nm-order As doping modulation is proposed to explain the enhanced GIDL for <e1>n</e1>⁺-As FETs and the suppressed B-B tunneling with increasing <e1>N</e1>_n- for large-tilt-angle implanted-drain devices. Band-to-defect tunneling via interface states is also simulated and found to limit device performance, as well as hot-carrier reliability, much more severely than B-B tunneling. Based on the above understanding, drain-structure design is discussed in view of both performance and reliability