Two-regime property dependence on plasma power of plasma-enhanced atomic layer-deposited In2O3 thin films and underlying mechanism

As the dimensions of electron devices are scaling down, the growth of high-quality thin film on high-aspect-ratio substrate conformally is in increasing demand. Atomic layer deposition (ALD) offers a solution for depositing conformal thin film. In this work, indium oxide (In2O3) thin film with high electron mobility and wide band gap was prepared by ALD. O2 plasma was used to enhance the growth rate to a reasonable level, which is difficult to achieved for In2O3 film grown by thermal ALD. The film properties and deposition mechanisms under different plasma power were investigated. A two-regime property dependence on plasma power was observed and explained by a two-reaction-mode mechanism. When deposited with a lower plasma power of 2000-2500 W, the adsorbed In-precursor ligands were not completely oxidized due to the less energetic oxygen radicals, resulting in lower growth rate, lower crystallinity and lower carrier mobility. When deposited with a higher plasma power of 2750-3000 W, the oxygen radicals were energetic enough to completely oxidize the In-precursor ligands, resulting in higher growth rate, higher crystallinity and higher carrier mobility. The results implied that deposition at higher plasma power is beneficial for enhancing the film growth rate and film properties.

Automated summary

As the dimensions of electron devices are scaling down, there is an increasing demand for high-quality thin film on high-aspect-ratio substrate. Atomic layer deposition (ALD) provides a solution for conformal thin film deposition. In this work, indium oxide (In2O3) thin film with high electron mobility and wide band gap was prepared by ALD. O2 plasma was used to enhance the growth rate, and the film properties and deposition mechanisms under different plasma power were investigated. A two-regime property dependence on plasma power was observed and explained by a two-reaction-mode mechanism. Higher plasma power was found to be beneficial for enhancing the film growth rate and properties.