Electrical Characteristics and Temperature Response of Al2O3 Gate Dielectrics with and without Nitric Acid Compensation

Abstract

In this paper, the Al2O3 gate dielectrics prepared by the in situ oxidation of sputtered Al in Ar/O2 ambient at room temperature and then without and with HNO3 compensation are demonstrated. It was found that the saturation substrate injection currents of MOS capacitors with P-type Si substrate at the positive bias region exhibit perimeter-dependent characteristics due to the enhanced fringing field effect. The temperature responses of perimeter-dependent saturated currents are different between two samples. The sample with HNO3 compensation shows regular dependence of substrate current on ni, but the one without HNO3 compensation exhibits additional current components come from oxide nonuniformity and interface trap density. The gate leakage current density at the negative bias region and the time-dependent dielectric breakdown reliability at 25 oC and 125 oC of Al2O3 capacitors can be improved by utilizing HNO3 compensation. It is believed that the HNO3 compensation is beneficial to the improvement of the SiO2/Si interface and the quality of the Al2O3/SiO2 oxide stacks.