In this study, the characteristics of Ta/chemical SiO2/Si devices with their chemical oxides formed by various chemicals, including HNO3, SC1 and H2SO4+H2O2 solutions, were first investigated. We found the HNO3 split depicts the lowest leakage current and the best hysteresis behavior. Next, chemical oxide formed by HNO3 was applied to form the interfacial SiO 2 layer for metal-oxide-semiconductor (MOS) devices with Ta/HfAlO/chemical SiO2/Si structrue. The effects of a high-temperature spike anneal were then studied. We found that the spike-anneal process can effectively reduce the thickness of the chemical oxide from 10 to 7 Å, thus is beneficial in preserving the low effective oxide thickness (EOT) of the structure. Furthermore, both the gate leakage current and stress-induced leakage current (SILC) were also effectively suppressed by the high-temperature spike-anneal.
- Chemical oxide