Influence of atomic layer deposition parameters on the phase content of Ta2O5 films

Ta2O5 films were grown in atomic layer deposition (ALD) process on barium borosilicate glass substrates in the temperature range of 300-400 degrees C from TaCl5 and H2O. The film crystallinity was modified by precursor dosing and substrate temperature. The films deposited at temperatures somewhat above 300 degrees C were partly crystallized, showing XRD reflections of hexagonal delta-Ta-2 O-5 phase. The reflection intensities and film haziness demonstrated maxima at certain values of the TaCl5 pulse length. The film growth rate initially decreased with the increase in the pulse length. After exceeding the TaCl5 pulse length value corresponding to the maximum in the crystallinity, the Ta-2 O-5 growth rate was stabilized. The intermediate delta-Ta-2 O-5 was transformed into the conventional low-temperature orthorhombic beta-Ta-2 O-5 upon raising the growth temperature above 325 degrees C and increasing the TaCl5 doses. (C) 2000 Elsevier Science B.V. All rights reserved.