Al 2 O 3 /InGaAs Metal-Oxide-Semiconductor Interface Properties: Impact of Gd 2 O 3 and Sc 2 O 3 Interfacial Layers by Atomic Layer Deposition

Abstract

© 2014 The Electrochemical Society. The use of InGaAs as a high carrier mobility CMOS-channel material requires a proper electrical passivation of its interface with the gate dielectric. We investigate InGaAs passivation by Atomic Layer Deposition (ALD) of Al 2 O 3 , Gd 2 O 3 , and Sc 2 O 3 using tri-methylaluminum (TMA), ( i PrCp) 3 Gd, (MeCp) 3 Sc, and H 2 O as precursors. We discuss the impact of the starting precursor and TMA exposure during the initial cycles of Al 2 O 3 on the interface trap density (D it ), frequency dispersion, leakage current, and breakdown field. Increasing the TMA pulse time to five seconds during the first five cycles reduce the D it to 1.8×10 12 eV -1 cm -2 , while frequency dispersion, leakage current and breakdown field generally improve. Gd 2 O 3 and Sc 2 O 3 interfacial layers between InGaAs and Al 2 O 3 are examined. The initial growth study of Gd 2 O 3 ALD on InGaAs indicates growth inhibition as compared to the hydrophilic SiO 2 /Si substrate. Gd 2 O 3 and Sc 2 O 3 improve the interface in terms of D it and border traps. The improvement depends on the initial precursor pulse lengths, and on the Gd- or Sc-content. The lowest D it values, 2.5×10 12 eV -1 cm -2 and 1.8×10 12 eV -1 cm -2 , are obtained for four cycles of Sc 2 O 3 and Gd 2 O 3 , respectively. Interfacial self-cleaning by TMA, ( i PrCp) 3 Gd, and (MeCp) 3 Sc is demonstrated by X-ray Photo-electron Spectroscopy and Time-of-flight secondary ion mass Spectroscopy.