Effect of substrate-enhanced and inhibited growth on atomic layer deposition and properties of aluminum–titanium oxide films

Abstract Atomic layer deposition of aluminum–titanium oxide films from different precursor combinations was investigated. In addition to well-known TiCl 4 –H 2 O, AlCl 3 –H 2 O and Al(CH 3 ) 3 –H 2 O ALD processes, combination of hydrogen-free TiCl 4 –O 3 and AlCl 3 –O 3 processes was used. Most of the films were grown at 350 °C because this temperature ensured reliable growth of TiO 2 and Al 2 O 3 in all processes combined. The films were deposited using supercycles that contained 1–60 successive cycles for deposition of TiO 2 followed by 1–3 cycles for deposition of Al 2 O 3 . The films were amorphous, when 15 or less TiO 2 cycles per Al 2 O 3 cycle were applied in a supercycle, and contained anatase when ≥ 30 TiO 2 cycles were applied. A marked increase in the Al deposition per cycle was observed with the increase of the number of TiO 2 cycles per supercycle from 0 to 5–10. With the further increase of the number of TiO 2 cycles from 15 per supercycle to higher values, the Al deposition per cycle depended on the precursor combination used. The Ti deposition per cycle depended, in turn, on the precursor system used for deposition of Al 2 O 3 layers. Deposition of Ti was most significantly hindered on Al 2 O 3 -rich surface deposited from AlCl 3 –O 3 and markedly enhanced on Al 2 O 3 deposited from Al(CH 3 ) 3 –H 2 O. In addition, the phase composition markedly influenced the growth rate of both components as well as the mean growth rate and surface roughness of the films.