ZrO2 film prepared by atomic layer deposition using less viscous cocktail CpZr[N(CH3)2]3/C7H8 precursor and ozone

Abstract

The precursor consists of a mixture of CpZr(NMe2)3 (Cp = C5H5, Me = CH3) and cycloheptatriene (C7H8), CpZr(NMe2)3/C7H8, is introduced as a precursor in the atomic layer deposition (ALD) of zirconium oxide (ZrO2). The cocktail CpZr(NMe2)3/C7H8 chemical exhibits a higher vapor pressure of 1.2 torr and a lower viscosity of 7.0 cP at 100 °C than the pure CpZr(NMe2)3. In the ALD of ZrO2 films, CpZr(NMe2)3/C7H8 and O3 act as the metal precursor and oxidant, respectively. Self-limited growth of ZrO2 films occurs after a 2 s pulse of CpZr(NMe2)3/C7H8, and a growth rate of 0.8–0.9 Å/cycle is obtained over a wide temperature range of 250–400 °C. ZrO2 film formed at 300 °C is stoichiometric with a lower impurity level of carbon and shows a tetragonal polycrystalline phase dominantly. The fabricated TiN/ZrO2/TiN capacitors exhibit compatible capacitance and leakage current properties with a quadratic voltage coefficient, inversely proportional to the dielectric film thickness (t) according to α∼t−1.8.