Liquid injection atomic layer deposition of Ti Ox films using Ti [OCH (C H3) 2] 4

Ti Ox films were prepared by liquid injection atomic layer deposition using titanium tetraisopropoxide (TTIP), Ti [OCH (C H3) 2] 4, dissolved in ethylcyclohexane (ECH). We analyzed the residual water content and the reaction with the TTIP for several solvents, choosing ECH for dissolving the TTIP because of the lowest residual water level and no ligand exchange reaction with the TTIP. Ti Ox films were deposited at 240°C with a wide range of the TTIP solution injections per cycle. However, an ideal self-regulated growth was not achieved for the Ti Ox films due to a slow catalytic decomposition of the TTIP molecules followed by the exchange reaction with the underling layer. The contribution of the catalytic decompositions to the deposition rates was suppressed by increasing the injection frequency of the TTIP solution into the vaporizer. A rather independent deposition rate of the input of the TTIP solution was achieved by increasing the injection frequency to 4 Hz, while Ti Ox films deposited with a low injection frequency of 0.25 Hz showed almost linear film growth rate to the input of the TTIP solution. The deposited Ti Ox films were amorphous and clearly showed both unipolar and bipolar resistive switching behaviors, which are applicable to nonvolatile memory applications.