Atomic layer deposition of $ZrO2$ on W for metal–insulator–metal capacitor application

A metal–insulator–metal (MIM) capacitor using $ZrO2$ on tungsten (W) metal bottom electrode was demonstrated and characterized in this letter. Both $ZrO2$ and W metal were synthesized by an atomic layer deposition (ALD) method. High-quality $110∼115 Å$ $ZrO2$ films were grown uniformly on ALD W using $ZrCl4$ and $H2O$ precursors at 300 °C, and polycrystalline $ZrO2$ in the ALD regime could be obtained. A $13∼14-Å$-thick interfacial layer between $ZrO2$ and W was observed after fabrication, and it was identified as $WOx$ through angle-resolved x-ray photoelectron spectroscopy analysis with wet chemical etching. The apparent equivalent oxide thickness was $20∼21 Å.$ An effective dielectric constant of $22∼25$ including an interfacial $WOx$ layer was obtained by measuring capacitance and thickness of MIM capacitors with Pt top electrodes. High capacitance per area $(16∼17 fF/μm2)$ and low leakage current $(10−7 A/cm2$ at ±1 V) were achieved.