Fabrication of n-metal–oxide semiconductor field effect transistor with Ta2O5 gate oxide prepared by plasma enhanced metalorganic chemical vapor deposition

Abstract

n-metal–oxide semiconductor field effect transistors (MOSFETs) were fabricated with plasma enhanced metalorganic chemical vapor deposited Ta2O5 gate oxide on Czochralski grown Si wafers using localized oxidation of silicon isolation technology by the conventional Si-based process. The Ta2O5 gate oxide n-MOSFETs showed excellent electrical characteristics such as subthreshold swing of 68–74 mV/dec, transconductance of 4 μS/μm for 4 μm gate length, and carrier mobility of 400 cm2/V s at the saturation region. The large Cox of the gate oxide with the high dielectric constant, εr=20–25, allowed the higher drain current of the device. During the whole process of n-MOSFET fabrication, the cross sectional transmission electron microscopy analysis of the Ta2O5/Si interface showed SiO2 interfacial oxide formation of about 35 Å thick. The Ta2O5 gate oxide n-MOSFET showed good performance compared to the high-temperature silicon oxide gate devices and thus has great potential for applications in the electronic devices.