Atomic ordering effect on SiGe electronic structureIn this paper, a realistic atomic model is used to study the atomic ordering effect on electronic structures of Si 0.5 Ge 0.5 . The hybrid density functional theory (DFT), HSE06, is chosen as the methodology. The calculated bandgap and effective masses of Si and Ge at various symmetry points are first validated by the reported experimental data and empirical pseudo-potential method (EPM) calculations. The study of two different Si 0.5 Ge 0.5 atomic configurations shows that the SiSi-GeGe case is more stable than SiGe-SiGe (RS2 structure). In addition, the electron effective masses of the former one are larger than those of the latter one, and those calculated by EPM with virtual crystal approximation (VCA). This large electron effective mass is attributed to the localized electron orbital of the lowest anti-bonding state in the SiSi-GeGe case which leads to a flat E-k curve. However, no obvious ordering effect on hole effective mass is found.
InAs Hole Inversion and Bandgap Interface State Density of 2x1011 cm-2 eV-1 at HfO2/InAs InterfacesHigh-k/InAs interfaces have been manufactured using InAs surface oxygen termination and low temperature atomic layer deposition of HfO2. Capacitance–voltage (C–V) curves revert to essentially classical shape revealing mobile carrier response in accumulation and depletion, hole inversion is observed, and predicted minority carrier response frequency in the hundred kHz range is experimentally confirmed; reference samples using conventional techniques show a trap dominated capacitance response. C–V curves have been fitted using advanced models including nonparabolicity and Fermi-Dirac distribution. For an equivalent oxide thickness of 1.3 nm, an interface state density Dit = 2.2 × 1011 cm−2 eV−1 has been obtained throughout the InAs bandgap. The authors would like to thank Y. C. Sun of TSMC and L. Samuelson of Lund University for their support.
Electrical Characterization and Materials Stability Analysis of La2O3/HfO2 Composite Oxides on n-In0.53Ga0.47As MOS Capacitors With Different Annealing TemperaturesIn this letter, a high-k composite oxide composed of La 2 O 3 and HfO 2 is investigated for n-In 0.53 Ga 0.47 As metal-oxide-semiconductor (MOS) capacitor application. The composite oxide was formed by depositing five layers of La 2 O 3 (0.8 nm)/HfO 2 (0.8 nm) on InGaAs with post deposition annealing at 500°C. The MOS capacitors fabricated show good inversion behavior, high capacitance, low leakage current, with excellent interface trap density (D it ) of 7.0×10 11 cm -2 eV -1 , small hysteresis of 200 mV and low capacitance equivalent thickness of 2.2 nm at 1 kHz were also achieved.
InAs N-MOSFETs with record performance of Ion = 600 uA/um at Ioff = 100 nA/um (Vd = 0.5 V)Record setting III-V MOSFETs are reported. For the first time performance better than state-of-the-art HEMTs is demonstrated. For a MOSFET with 10 nm unstrained InAs surface channel and L g = 130 nm operating at 0.5 V, on-current as high as I on = 601 μA/μm (at fixed I off = 100 nA/μm) is achieved. This record performance is enabled by g m, ext = 2.72 mS/μm and S = 85 mV/dec, DIBL = 40 mV/V, resulting from breakthroughs in epitaxy and III-V/dielectric interface engineering. Measured mobility is 7100 cm 2 /V.s at n s = 6.7×10 12 cm -2 . Device simulations further elucidate the performance potential of III-V N-MOSFETs.
Scaled p-channel Ge FinFET with optimized gate stack and record performance integrated on 300mm Si wafersWe demonstrate scaled, replacement gate high-k/metal gate p-channel Ge FinFETs integrated onto 300mm Si wafers for which the best device shows record peak g m, ext =2.7mS/μm (g m, int =3.3mS/μm), Q (≡g m, ext /SS sat ) = 32.4 and I on = 497μA/μm at I off = 100nA/μm, all at V ds = -0.5V. The high performance is a result of successful integration of <;110> oriented, highly scaled Ge fins on silicon substrates and of a low D it gate stack with capacitance equivalent thickness=8Å. This optimized gate stack supports the highest hole mobility ever reported at sub-10Å CET. Furthermore, Ge FinFETs in the present work outperform any other reported Ge devices by more than ~2.5× (g m /SS metric) and ~2× (I on /I off metric) at shortest gate lengths (down to 20nm) to the best of our knowledge.
Electrical Characteristics of Al2O3/InSb MOSCAPs and the Effect of Postdeposition Annealing TemperaturesThe characteristics of Al2O3/InSb MOSCAPs processed with different postdeposition annealing (PDA) temperatures are investigated. X-ray photoelectron spectroscopy analysis shows a significant reduction of InSb-oxides after HCl plus trimethyl aluminum treatment and oxide deposition. Multifrequency capacitance-voltage (C–V) characteristics exhibit low-frequency and asymmetrical C–V behaviors, in which capacitance in the InSb conduction band side is lower than in the valence band side. The electrical properties of the MOSCAPs are sensitive to PDA temperature and degraded significantly at PDA temperature > 300 °C. This degradation is closely related to the diffusion of In, Sb into Al2O3 as indicated by transmission electron microscopy analyses.
Electrostatics and ballistic transport studies in junctionless nanowire transistorsIn this work a drift-diffusion simulator is utilized to study the electrostatics of a cylindrical gate-all-around junctionless nanowire transistor. For carrier transport properties such as carrier scattering and velocity in channel, a full band Monte Carlo is adopted to simulate non-equilibrium and ballistic behaviors. Two major cases: different S/D extension schemes and channel doping effects are examined in this study. It is observed that S/D extension underlap can benefit short-channel control and carrier velocity. In addition, channel doping is found to play an import role to increase carrier injection velocity in the junctionless nanowire transistors.
Quantum confinement point of view for mobility and stress responses on (100) and (110) SingleGate and double-gate nMOSFETsImpact of quantum confinement on electron mobility and its stress responses for (100) and (110)-orientated single-gate (SG) and double-gate (DG) nMOSFETs is studied. Unstrained electron mobility in (110) DG nMOSFETs is found to be significantly higher than that of (110) SG devices. This paper discusses another physical explanation to the experimentally observed higher electron mobility in (110) FinFET sidewall channels as compared to that observed in planar (110) devices. It is also found that the electron mobility increases faster under uniaxial tensile stress for (110) devices than for (100) ones. The higher mobility in (110) DG devices is attributed to the lighter confinement effective mass of Δ4 valleys and the non-parabolicity of Δ2 valleys along the <;110> directions. With high enough tensile strain, DG nMOSFETs with (110) surface orientation are expected to outperform these on (100).
MOVPE-grown InAs/AlAs0.16Sb0.84/InAs and InAs/AlAs0.16Sb0.84/GaSb heterostructuresWe demonstrate MOVPE-growth of InAs/AlAs0.16Sb0.84/GaSb and InAs/AlAs0.16Sb0.84/InAs heterostructures of excellent quality as observed by transmission electron microscopy and x-ray diffraction 2-theta-omega and rocking curve scans with full width at half maximum routinely below 100″. Key points regarding interface control for heteroepitaxial nucleation are reviewed and the choice of suitable precursors to minimize the incorporation of C and O are discussed.
Growth of Heterostructures on InAs for High Mobility Device ApplicationsThe growth of heterostructures lattice matched to InAs(100) substrates for high mobility electronic devices has been investigated. The oxide removal process and homoepitaxial nucleation depends on the deposition parameters to avoid the formation of surface defects that can propagate through the structure during growth which can result in degraded device performance. The growth parameters for InAs homoepitaxy were found to be within an extremely narrow range when using As4 with a slight increase using As2. High structural quality lattice matched AlAsxSb1−x buffer layer was grown on InAs(100) substrates using a digital growth technique with the AlAs mole fraction adjusted by varying the incident As flux. Using the AlAsxSb1−x buffer layer, the transport properties of thin InAs channel layers were determined on conducting native substrates.
TSMC has been at the forefront of advanced CMOS logic technologies for which dense transistors are one of the two essential building blocks, the other being dense interconnect stacks. The intrinsic computing capability of a given logic technology is directly related to the number of interconnected transistors and their switching speed under representative loads originating from both the transistor or gates being driven and the related interconnect resistive and capacitive circuit loads.
TSMC research and development is continuously exploring novel and scalable transistor concepts to ensure sustainable, cost-effective, leading-edge logic technology performance and energy efficiency. We invite you to explore some of TSMC research areas in transistor structure, high-mobility channel, and low-dimensional materials and devices.