In-situ Atomic-Layer-Deposited Al2O3 on In0.53Ga0.47As – Push of High Performance Inversion-Channel MOSFET
H. W. Wan1*, Y. C. Chang1, T. D. Lin1, M. H. Chen2, K. Y. Lin1, S. H. Chen3, T. W. Pi4, J. Kwo5, M. Hong1
1Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei, Taiwan
2Graduate Institute of Electronic Engineering, National Taiwan University, Taipei, Taiwan
3National Device Laboratories, Hsinchu, Taiwan
4National Synchrotron Radiation Research Center, Hsinchu, Taiwan
5Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Hsien-Wen Wan,
Driven by the demands of high-speed and low-power digital electronic devices, InGaAs is a promising channel candidate to replace silicon for the nMOSFET due to its intrinsic high electron mobility. However, the high interfacial trap densities (Dit) at the dielectric/InGaAs interface have caused the poor electrical performance of the corresponding inversion-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). In this work, Al2O3 has been deposited on In0.53Ga0.47As using atomic-layer-deposition (ALD) via in-situ and ex-situ approaches; in the former method, Al2O3 was directly deposited on freshly molecular-beam-epitaxy (MBE) grown In0.53Ga0.47As with the wafer transfer being in ultra-high vacuum, while in the latter, In0.53Ga0.47As was exposed to air prior to the oxide deposition. Frequency dispersion of 10.8% and 21.5% in the accumulation were obtained in the in-situ and ex-situ samples using the capacitance-voltage (CV) measurements, respectively. Interfacial trap densities (Dit) of 2 x 1012 and 4.5 x 1012 cm-2eV-1, respectively, were measured from the in-situ and ex-situ samples using the conductance method. The in-situ process has improved the interfacial electronic characteristics and greatly enhanced the device performances; it has given extrinsic drain currents (Id) of 1.84 mA/μm, transconductance (Gm) of 0.98 mS/μm, SS of 128mV/dec, and effective electron mobility (μeff) of > 1,250 cm2/Vs, while the ex-situ approach gave the respective device performances of 0.56 mA/μm, 0.28 mS/μm, and 410 cm2/Vs in the 1 μm gate length (Lg) self-aligned inversion-channel MOSFETs. Moreover, employment of Rsd of 122 Ω-μm (a targeted International Technological Road for Semiconductor (ITRS) value in 2019) and a Dit of 2 x 1012 cm-2eV-1 (already attained in the MOSCAPs from the same wafer by the conductance method) would lead to an SS of 79 mV/dec, an Id of > 3mA/μm at Vd = 0.7V, and Vg -Vth= 0.77V.

Keywords: Atomic Layer Deposition, InGaAs, MOSFET, Drain Current