Searching Optimal Growth Parameters for HfO₂ Applied by Plasma-Enhanced Atomic Layer Deposition Method

The properties of thin HfO
2
films grown by plasma-enhanced atomic layer deposition on Si substrates at various temperatures 80,120, and $160^{\circ} \mathrm{C}$ are studied in this work. For each temperature, the dependences of the growth rate per cycle on the post-plasma pumping time were determined. For the majority of temperatures, saturation of the growth rate per cycle depend of the post-plasma purge time was observed. Accordingly, the optimal times of growth stages were determined for temperatures 80,120, and $160^{\circ} \mathrm{C}$. Studies of the chemical composition of the HfO
2
film by the XPS method showed that hafnium is bound to oxygen,and increasing of the post-plasma purge time reduces the content of suchimpurities as nitrogen and carbon. The electrophysical properties of HfO
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films have been measured: such asthe capacitance, the dielectric constant and theleakage current density. The values of the built-in charge in HfO
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film were 2.92 and $2.08 \times 10^{-7} \mathrm{C} / \mathrm{cm}^{2}$ for growth temperaturesof $120^{\circ} \mathrm{C}$ and $160^{\circ} \mathrm{C}$, respectively. The dielectric constant for the HfO
2
film was 10.8 and 11.8 for temperatures of 120 and $160^{\circ} \mathrm{C}$, respectively.