Combination of ultraviolet exposure and thermal post-treatment to obtain high quality HfO 2 thin films

The characteristics of HfO2 thin films obtained with and without ultraviolet (UV) exposure post-treatment are discussed. First, 30-nm-thick HfO2 thin films are deposited on silicon wafer substrates using atomic layer deposition followed by a combination of UV exposure and low-temperature thermal post-treatment. Compared with the samples without UV treatment, the HfO2 samples with post-treatment showed a smaller suboxide bond proportion of 2.59%, along with increased crystallinity. The use of a UV-treated gate dielectric HfO2 film in a MOS capacitor device results in lower interface trap and fixed charge densities. Furthermore, the dielectric constant of the HfO2 thin film with the treatment is 22.03, which is higher than that of the film without the treatment, that is, 14.98. In addition, the device capacitance was improved by 56% with the treatment. These results demonstrate the significant potential of the proposed post-treatment process in improving the quality of HfO2 thin films for semiconductor devices.