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/ZrO2/p-Si metal-insulator-semiconductor structures were fabricated. Epitaxial crystallization of a high-k ZrO2 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-ZrO2 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 ZrO2 films that is induced by the low pulse duration ratio under the applied target power of 500W, 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 ZrO2 films, not only influence the crystallographic texture of ZrO2 films but also degrade the hysteretic characteristics.