Preparation by pulsed laser deposition and characterization of ZrO/sub 2/, HfO/sub 2/ and PrO/sub x/ thin films for high-k gate insulator

High-k thin films of ZrO/sub 2/, HfO/sub 2/ PrO/sub x/ of /spl sim/10 nm thickness have been prepared by pulsed laser deposition (PLD), and characterized in microscopic structure and electrical properties. Crystallization is promoted in ZrO/sub 2/ films deposited above 400/spl deg/C, but a significant XRD peak was not observed in the ZrO/sub 2/ film grown below 400/spl deg/C. Moreover, density of the film is confirmed to saturate above 400/spl deg/C by grazing incident angle X-ray reflectance. The leakage current is decreased by increasing growth temperature, but an equivalent-oxide thickness (EOT) obtained from accumulation capacitance of C - V characteristics becomes large. HfO/sub 2/ films show the similar behaviors to ZrO/sub 2/ films. The films deposited at 400/spl deg/C were annealed at 400/spl deg/C in O/sub 2/ gas to reduce the leakage, but the EOTs become large. So, these films were irradiated with oxygen radical at the pressure of 10/sup -3/ Pa both to prevent the growth of interfacial layer and to enhance the oxidation of only the films. Although the leakage of ZrO/sub 2/ films can be reduced by oxygen radical irradiation, only small improvement is observed in the PrO/sub x/ films.