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

Abstract

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.