Characteristics of metal-gate metal-insulator-semiconductor capacitor with ZrN capping layer fabricated by high-power impulse magnetron sputtering
Abstract Metal-gate Al/TiN/ZrN/ZrO 2 /p-Si metal-insulator-semiconductor structures were fabricated. Epitaxial crystallization of a high-k ZrO 2 thin-film was induced by conventional direct current magnetron sputtering (DCMS) or high-power impulse magnetron sputtering (HIPIMS) to enable the subsequent deposition of a ZrN capping layer on it. The HIPIMS-deposited ZrN samples have more favorable physicochemical and capacitance-voltage characteristics than DCMS- deposited ZrN samples. The insufficient power density and the ionization rate of the sputtered metallic atoms during ZrN thin film deposition may cause the (111) planes of t-ZrO 2 to disappear in samples with DCMS-deposited ZrN thin films. The more crystalline texture and higher interface trap density arise from the formation of silicate in the ZrO 2 films that is induced by the low pulse duration ratio under the applied target power of 500 W, which corresponds to a high peak power density in the HIPIMS system. HIPIMS samples with a higher pulse duration exhibit greater hysteresis, strongly suggesting that the structural defects, such as oxygen vacancies in ZrO 2 films, not only influence the crystallographic texture of ZrO 2 films but also degrade the hysteretic characteristics.