Improved interfacial and electrical properties of Ge MOS capacitor by using TaON/LaON dual passivation interlayer

Abstract

The effects of TaON/LaON dual passivation interlayer on the interfacial and electrical properties of Ge metal-oxide-semiconductor (MOS) capacitor with HfO2 gate dielectric are investigated. As compared to its counterpart with only LaON as passivation interlayer, the formation of HfGeOx and LaHfOx, which would degrade the interfacial quality, is effectively suppressed due to the strong blocking role of the TaON barrier layer against Hf diffusion. As a result, excellent interfacial and electrical properties are achieved for the Ge MOS device with the TaON/LaON dual passivation interlayer: high k value (20.9), low interface-state density (5.32 × 1011 cm−2 eV−1) and oxide-charge density (−3.90 × 1012 cm−2), low gate leakage current density (1.77 × 10−4 A/cm2 at Vg = Vfb + 1 V), and high reliability under high-field stress.