Plasma and thermal ALD of Al2O3 in a commercial 200 mm ALD reactor

The deposition of Al2O3 by remote plasma atomic layer deposition (ALD) in the Oxford Instruments FlexAL reactor was studied and compared with results from thermal ALD in the same reactor. Trimethylaluminum [Al(CH3)3] was used as the metal precursor and O2 plasma and H2O were used as oxidizing agents for the plasma and thermal processes, respectively. For remote plasma ALD with a total cycle time of 4 s, the growth per cycle decreased monotonically with substrate temperature, from 1.7 Å/cycle at 25°C to 1.0 Å/cycle at 300°C. This growth per cycle was consistently higher than that obtained for thermal ALD. For the latter a maximum growth per cycle of ~1.0 Å/cycle was found at 200°C. The film properties investigated were nearly independent of oxidant source for temperatures between 100 and 300°C, with a slightly higher mass density for the remote plasma ALD Al2O3 films. Films deposited at 200 and 300°C were stoichiometric with a mass density of 3.0 g/cm3 and low C