Abstract
Effects of nitrogen concentration near the HfO x N y /Si interface on the charge trapping properties of metal-oxide-semiconductor (MOS) capacitors were investigated. The nitrogen concentration in HfO x N y gate dielectric was adjusted by sputtering the Hf target in a nitrogen-flow-modulated ambient. The trapped charges in the HfO x N y dielectric are positive. The mechanism related to the relatively large stress-induced leakage current (SILC) at low electrical fields can be explained using trap-assisted tunneling. On the other hand, the relatively small leakage current found at high electric fields can be attributed to the electron trapping in bulk defects. A small flat-band voltage shift and SILC are observed for devices with a HfO x N y dielectric containing a higher nitrogen at the dielectric/Si interface, which possesses less strain near the interface.