Effect of Processing Conditions on the Electrical Characteristics of Atomic Layer Deposited Al2O3 and HfO2 Films

Abstract

An extensive mercury-probe capacitance-voltage characterization is carried out on Al2O3 and HfO2 films deposited on silicon by atomic layer deposition (ALD) at different temperatures and subjected to various high-temperature post-deposition thermal treatments. For the case of the Al2O3 layers, higher flat-band voltages (Vfb) for higher deposition temperatures are obtained and positive Vfb shifts are always registered after the different thermal annealing conditions studied; however, the impact is found to be significantly different depending on the deposition temperature. On the contrary, smaller changes are observed for the case of the studied HfO2 layers. Interestingly for practical applications, the hystereses, as well as the Vfb shifts, clearly diminish for higher deposition temperatures or after a thermal annealing treatment. The results obtained from ellipsometry suggest that significant physical changes occur under the highest temperature treatments in either, the ALD Al2O3 or HfO2 layers and/or its interface with the silicon substrate.