PAPER Special Section on Fundamentals and Applications of Advanced Semiconductor Devices Influence of Si Surface Roughness on Electrical Characteristics of MOSFET with HfON Gate Insulator Formed by ECR Plasma Sputtering

SUMMARY To improve metal oxide semiconductor field effect tran-sistors (MOSFET) performance, flat interface between gate insulator andsilicon (Si) should be realized. In this paper, the influence of Si surfaceroughness on electrical characteristics of MOSFET with hafnium oxyni-tride (HfON) gate insulator formed by electron cyclotron resonance (ECR)plasma sputtering was investigated for the first time. The surface roughnessof Si substrate was reduced by Ar/4.9%H 2 annealing utilizing conventionalrapid thermal annealing (RTA) system. The obtained root-mean-square(RMS) roughness was 0.07nm (without annealed: 0.18nm). The HfONwas formed by 2nm-thick HfN deposition followed by the Ar/O 2 plasmaoxidation. The electrical properties of HfON gate insulator were improvedby reducing Si surface roughness. It was found that the current drivabilityof fabricated nMOSFETs was remarkably increased by reducing Si surfaceroughness. Furthermore, the reduction of Si surface roughness also leadsto decrease of the 1/