Titanium isopropoxide as a precursor for atomic layer deposition:: characterization of titanium dioxide growth process

Atomic layer deposition (ALD) of titanium oxide from titanium isopropoxide (Ti(OCH(CH,),),) and water as well as from Ti(OCH(CH3)(2))(4) and hydrogen peroxide (H2O2) was studied. According to data of real-time quartz crystal microbalance (QCM) measurements, adsorption of Ti(OCH(CH,),), was a self-limited process at substrate temperatures 100-250 degrees C. At 200-250 degrees C, the growth rate was independent of whether water or H2O2 was used as the oxygen precursor. Insufficient reactivity of water vapor hindered the film growth at temperatures 100-150 degrees C. Incomplete removal of the precursor ligands from solid surface by water pulse was revealed as the main reason for limited deposition rate. The growth rate increased significantly and reached 0.12 nm per cycle at 100 degrees C when water was replaced with H2O2. The carbon contamination did not exceed 1 at.% and the refractive index was 2.3 in the films grown at temperatures as low as 100 degrees C. (C) 2000 Elsevier Science B.V. All rights reserved.