Study of Aluminum Oxide Films Deposited using Thermal ALD and Effect of Low Thermal Budget Annealing

Thermal ALD deposited Al2O3 films on silicon show marked difference in surface passivation quality as a function of annealing time (using rapid thermal process). An effective and quality passivation is realized in short anneal duration (~100s) which is reflected in the low surface recombination velocity (SRV <10 cm/s). The deduced values are close to the best reported SRV obtained by high thermal budget process (with annealing time between 10-30 min) conventionally used for improved surface passivation. Both as-deposited and low thermal budget annealed films show the presence of positive fixed charges and has never been reported in the literature before. The role of field and chemical passivation is also investigated in terms of fixed charge and interface defect densities. Further, the importance of anneal step sequence in MIS structure fabrication protocol is also investigated from the view point of its effect on nature of fixed changes.