A Comparative Study of Nitrogen Gas Flow Ratio Dependence on the Electrical Characteristics of Sputtered Titanium Nitride Gate Bulk Planar Metal–Oxide–Semiconductor Field-Effect Transistors and Fin-Type Metal–Oxide–Semiconductor Field-Effect Transistors

Abstract

Sputtered titanium nitride (TiN) metal gates fabricated at different nitrogen gas flow ratios [RN=N2/(N2+Ar)] from 17 to 100% have systematically been investigated, and the RN dependence on the electrical characteristics of fabricated TiN metal gate bulk planar metal–oxide–semiconductor field-effect transistors (MOSFETs) and fin-type MOSFETs (FinFETs) are clarified. It is experimentally found that the electrical characteristics of FinFETs such as subthreshold slope (S-slope) and mobility are almost independent of RN, while those of bulk planar MOSFETs markedly deteriorate with increasing RN. These experimental results are discussed from the viewpoint of the device structure differences and the direction of energetic nitrogen atoms in sputtering. The threshold voltage (Vth) of FinFETs can be adjusted to about 100 mV by controlling RN without device performance degradation. These results are very useful in setting an appropriate Vth for TiN gate-last FinFETs.