A low temperature fabrication of HfO{sub 2} films with supercritical CO{sub 2} fluid treatment

To improve the dielectric properties of sputter-deposited hafnium oxide (HfO{sub 2}) films, the supercritical CO{sub 2} (SCCO{sub 2}) fluid technology is introduced as a low temperature treatment. The ultrathin HfO{sub 2} films were deposited on p-type (100) silicon wafer by dc sputtering at room temperature and subsequently treated with SCCO{sub 2} fluids at 150 deg. C to diminish the traps in the HfO{sub 2} films. After SCCO{sub 2} treatment, the interfacial parasitic oxide between the Si substrate and HfO{sub 2} layer is only about 5 A, and the oxygen content of the HfO{sub 2} films apparently increased. From current-voltage (I-V) and capacitance-voltage (C-V) measurements, the leakage current density of the SCCO{sub 2}-treated HfO{sub 2} films is repressed from 10{sup -2} to 10{sup -7} A/cm{sup 2} at electric field=3 MV/cm due to the reduction of traps in the HfO{sub 2} films. The equivalent oxide thickness also obviously decreased. Besides, the efficiency of terminating traps is relative to the pressure of the SCCO{sub 2} fluids.