Passivation performance improvement of ultrathin ALD-Al2O3 film by chemical oxidation

We investigated the passivation performance improvement of ultrathin Al2O3 tunnel oxide by chemical oxidation. The thickness of the Al2O3 tunnel oxide deposited by atomic layer deposition (ALD) was about 1 nm. The surface treatment was prepared as a function of chemical-oxidation time before ALD-Al2O3 growth. The Al2O3 films on surface-treated wafers showed improved passivation performance compared with the Al2O3 films on untreated wafers. The electrical characteristics showed that the surface-treated films, due to their enhanced initial ALD growth, enabled a low-interface-state defect and high film quality. In terms of tunneling and passivation performance, the optimal time of chemical oxidation was 2.5 min. The values of open-circuit voltage and carrier lifetime for the passivated tunnel oxide under this surface condition were 645 mV and 1 ms, respectively. A 1 nm ALD-Al2O3 films on surface treatment are applicable for passivated tunnel oxide.