Variability Improvement by Si Surface Flattening of Electrical Characteristics in MOSFETs With High-k HfON Gate Insulator

Variability improvement of metal-oxide-semiconductor field-effect transistors (MOSFETs) characteristics with high-k HfON gate insulator by Si surface flattening was investigated. The Si surface flattening process was carried out by Ar/4.9%H2anneal utilizing rapid thermal annealing system. The HfON gate insulator was formed by the in-situ Ar/O2plasma oxidation of HfN utilizing electron cyclotron resonance plasma sputtering followed by the post deposition anneal at 600 °C for 1 min. The Si surface flattening was found to significantly improve the threshold voltage variability (ΔVTH) of MOSFET with HfON gate insulator for the first time. Furthermore, the stability of the device characteristics was improved up to the measurement temperature of 100 °C by introducing the Si surface flattening process.