Effect of Process Pressure on Atomic Layer Deposition of Al2O3

Abstract

Aluminum oxide thin films have been prepared by the atomic layer deposition (ALD) using trimethylaluminum (TMA) and ozone as precursors. The process pressure was varied from at , and its effect on the film properties was compared to that of the deposition temperature change from . The film growth rate and film properties of thickness uniformity, impurity incorporation, and the step coverage in high aspect ratio features were characterized. It was found that the deposition temperature decrease led to film property deterioration and film growth rate increase. Increasing process pressure at lower temperature could not only help to retrieve the film properties, but also further increase the film growth rate. These improvements can be attributed to the change of surface saturation level, the enhancement of precursor diffusion condition, as well as the higher probability for surface reactions to occur at the active sites. The electrical and reliability performances on the dynamic random access memory capacitor confirmed the robustness of the high-pressure films. This study suggests that increasing process pressure may reduce the necessary cycle time/number to obtain the qualified film properties and the desired film thickness, which brings advantages of throughput for ALD semiconductor applications.