Effect of nitrogen content in HfxTayN metal gate on work function and thermal stability of advanced metal-oxide-semiconductor devices

Abstract

The effects of nitrogen composition in HfxTayN metal-gate electrodes and postmetal annealing (PMA) treatment on the electrical properties of metal-oxide-semiconductor (MOS) devices were investigated in this work. The work function of HfxTayN gate electrodes can be adjusted by incorporating various nitrogen contents. It is found that the HfxTayN metal gate with higher nitrogen content can achieve better electrical characteristics in terms of leakage current and reliability while with only a slight increase in equivalent-oxide-thickness value. The face that only slight variation on electrical characteristics of MOS device with HfxTayN gate electrodes is observed after various PMA temperatures designates the excellent thermal stability of HfxTayN gate electrodes. The present study indicates that HfxTayN is a promising metal-gate-electrode material for advanced MOS devices.