Low temperature chemical vapor deposition of ZrO₂ on Si(100) using anhydrous zirconium(IV) nitrate

Anhydrous zirconium(IV) nitrate was used as a volatile, carbon-free precursor for the low pressure chemical vapor deposition of thin ZrO₂ films on silicon (100) substrates. Depositions were performed at substrate temperatures between 300 and 500 °C at total reactor pressures between 0.25 and 1.1 Torr. During deposition the N₂ carrier gas (flow rates = 20 or 100 sccm) was diverted through the precursor vessel which was maintained between 80 and 95 °C. Under these conditions typical growth rates reached 10.0 nm/min. The polycrystalline films were predominantly monoclinic ZrO₂ with compositions very near the ideal value. Cross-sectional transmission electron microscopy and medium energy ion scattering established that an interfacial layer of SiO₂ separates the silicon substrate from the ZrO₂. Electrical measurements made on capacitors constructed of 58 nm thick films of ZrO₂ with a platinum top electrode suggest that charge trapping occurs in the Si/ZrO₂ interfacial region.