Liquid injection atomic layer deposition of perovskite-type multi-component oxide thin films for ferroelectric and higher-k three dimensional capacitor structures

Quaternary Pb(Zr,Ti)Ox [PZT] films were deposited at 240°C by a combination of liquid injection atomic layer depositions (ALD) of binary PbO, TiOx, and ZrOx thin films. To find the optimum set of precursors different combinations of five precursors were tested: Pb(C11H19O2)2 [Pb(DPM)2], Ti(OC3H7)2(C11H19O2)2 [Ti(Oi-Pr)2(DPM)2] or Ti(OC3H7)4 [Ti(Oi-Pr)4], and Zr(C11H19O2)4 [Zr(DPM)4] or Zr(C9H15O2)4 [Zr(DIBM)4]. Each precursor was dissolved in ethylcyclohexane (ECH) and was separately injected into a vaporizer. Water vapor was used as oxidant. The deposition rates of the metal elements were investigated as a function of the input of the solutions. Using the set of 0.1M Pb(DPM)2, Ti(Oi-Pr)4, and Zr(DIBM)4 solutions resulted in PZT films with good uniformity on 3D structured substrates. The Zr to Ti ratio in the as-deposited PZT films could be adjusted in the range up to Zr/Ti =1. This study suggests that the multi-layer stacking liquid delivery ALD process is an effective method for building up homogeneous layers of multi-component materials on desired 3D structures.