Rapid thermal chemical vapor deposition of zirconium oxide for metal-oxide-semiconductor field effect transistor application

${\mathrm{ZrO}}_2$ is investigated in this work to replace ${\mathrm{SiO}}_2$ as the gate dielectric material in metal-oxide-semiconductor devices for its high dielectric constant, good thermal stability on silicon, and large band gap. ${\mathrm{ZrO}}_2$ films were deposited on $\mathrm{p-}\mathrm{Si}\text{(100)}$ wafers by a rapid thermal chemical vapor deposition process using a zirconium (IV) t-butoxide ${\mathrm{Zr(OC}}_{\mathrm{4}}{\mathrm{H}}_9{)}_4$ precursor and oxygen. At temperatures between 300 and 400 °C, the reaction was thermally activated with an activation energy of 29 kcal/mol, consistent with a β-hydride elimination mechanism leading to ${\mathrm{ZrO}}_2$ deposition. In this regime at substrate temperatures below 350 °C, one atomic layer of ${\mathrm{ZrO}}_2$ can be deposited after each alternating exposure to the precursor and oxygen, ideal for achieving conformal coverage of ${\mathrm{ZrO}}_2$ over high aspect ratio features. Stoichiometric, uniform, and amorphous ${\mathrm{ZrO}}_2$ was obtained, and highly conformal step coverage of the deposited ${\mathrm{ZrO}}_2$ was observed on 300 nm features with an aspect ratio of 4. The dielectric constant of ${\mathrm{ZrO}}_2$ achieved in this work ranged from 15 to 18 depending upon process conditions and small $\mathrm{C–V}$ hysteresis and low interfacial state density were observed, ideal for metal-oxide-semiconductor field effect transistor application.