Effect of Si surface roughness on electrical characteristics of HfON gate insulator formed by ECR plasma sputtering

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In this paper, the effect of Si surface roughness on electrical characteristics of HfON gate insulator formed by the electron cyclotron resonance (ECR) plasma sputtering was investigated. In order to improve the electrical characteristics of HfON gate insulator, interface roughness between HfON and Si substrate should be reduced. The surface roughness of Si substrate was reduced by 1 μm-thick wet oxidation followed by the wet etching (HCl:HF=19:1). The obtained R_<MS> roughness was 0.11 nm (as-cleaned: 0.21 nm). The HfON was formed by 1 nm-thick HfN deposition utilizing ECR plasma sputtering followed by the Ar/O_2 plasma oxidation. The 600℃ PDA was carried out for 1 min in N_2 ambient. It was found that the leakage current was decreased from 2 x 10^<-3> A/cm^2 to 3 x 10^<-4> A/cm^2 at V_<FB>-1 V by reducing the Si surface roughness.
2011-10-13