Effect of Al inclusion in HfO/sub 2/ on the physical and electrical properties of the dielectrics

This authors present the effect of Al inclusion in HfO/sub 2/ on the crystallization temperature, leakage current, band gap, dielectric constant, and border traps. It has been found that the crystallization temperature is significantly increased by adding Al into the HfO/sub 2/ film. With an addition of 31.7% Al, the crystallization temperature is about 400-500/spl deg/C higher than that without Al. This additional Al also results an increase of the band gap of the dielectric from 5.8 eV for HfO/sub 2/ without Al to 6.5 eV for HfAlO with 45.5% Al and a reduced dielectric constant from 19.6 for HfO/sub 2/ without Al to 7.4 for Al/sub 2/O/sub 3/ without Hf. Considering the tradeoff among the crystallization temperature, band gap, and dielectric constant, we have concluded that the optimum Al concentration is about 30% for conventional self-aligned CMOS gate processing technology.