Fabrication of low interface dipole layer on Al2O3/SiO2/Si structure by densification of interfacial layer

Abstract

Interfacial defects and electrical characteristics were analyzed to confirm the formation of dipole due to the densification of the SiO2 buffer layer and the resulting movement of the flat-band voltage. Through the NAOS, the SiO2 layer was densified without any change in thickness, and the suboxide density after the NAOS decreased from 2.23 × 1014 atoms/cm2 (PE-CVD) to 1.33 × 1014 atoms/cm2 (PE-CVD+NAOS). In addition, both electrical and interfacial defects decreased after NAOS and PMA. From these results, the SiO2 buffer layer through the NAOS was densified and the interface defect state density was reduced. The PE-CVD sample with low atomic density had a dipole layer strength of 0.799 V before PMA, but it was 0.457 V in the case of PE-CVD+NAOS with high atomic density due to the densification of the SiO2 buffer layer. Also, both samples were reduced to 0.488 V and 0.422 V after PMA. Based on this, the leakage current of PE-CVD was measured to be 3.05 × 10−5 A/cm2, and the leakage current of PE-CVD+NAOS was measured that the difference in about four orders of magnitude was 1.64 × 10−9 A/cm2. Through the densification of the SiO2 layer, the interface atomic density increased, and consequently, the dipole layer strength decreased, thereby improving the electrical properties.