Plasma-assisted ALD of Al2O3 at low temperatures : reaction mechanism and material properties

Multiple in situ diagnostics have been employed to study the reaction mechanism of plasma-assisted ALD of Al2O3 and the influence of the substrate temperature on the material properties obtained. The results demonstrate that the ALD mechanism is governed by the formation of -CH3 surface groups and CH4 byproducts upon A1(CH 3)3 adsorption, while -OH surface groups and H 2O, CO, and CO2 by-products are formed during the remote O2 plasma step. It has been observed that the amount of-OH involved in the ALD process increases with decreasing substrate temperatures which can account for the increase in growth per cycle at lower substrate temperatures. Moreover for substrate at 25 °C, it has been found that a prolonged plasma exposure in the ALD cycle is effective in improving the film quality by a reduction of the impurity content and an increase in the mass density. © The Electrochemical Society