N. C. Su

High-Performance InGaZnO Thin-Film Transistors Using HfLaO Gate Dielectric

In this letter, we report a low-voltage-driven amorphous indium-gallium-zinc oxide thin-film transistor with a high-kappa-value HfLaO gate dielectric. Good characteristics were achieved including a low <i>VT</i> of 0.22 V, small subthreshold swing of 76 mV/dec, high mobility of 25 cm²/ Vmiddots, and large <i>I</i> _on/<i>I</i> _off ratio of 5 times 10⁷. These good performances are obtained at an operation voltage as low as 2 V. These characteristics are attractive for high-switching-speed and low-power applications.

Low-Voltage-Driven Flexible InGaZnO Thin-Film Transistor With Small Subthreshold Swing

A flexible thin-film transistor (TFT) was made by integrating a high- HfLaO gate dielectric and an amorphous-InGaZnO (a-IGZO) active layer on a polyimide substrate. This flexible HfLaO/a-IGZO TFT exhibits a low threshold voltage of 0.1 V, a small subthreshold swing of 0.18 V/dec, a high maximum saturation mobility of 22.1 cm2/V s, and an acceptable on/off current ratio of 2 × 10-5. The low threshold voltage and small subthreshold swing allow the device to operate at 1.5 V for low-power applications, which should enable significant future progress in energy efficiency.

A Nonvolatile InGaZnO Charge-Trapping-Engineered Flash Memory With Good Retention Characteristics

We report an amorphous indium gallium zinc oxide (a-IGZO) thin-film transistor nonvolatile memory (NVM). This NVM shows a large 1.2-V extrapolated ten-year memory window, along with low 10-V/-12-V program/erase voltage, fast 1-ms/100-¿s speed, and good endurance. This was achieved using a charge-trap-engineered structure and high- ¿ layers.

Very Low V t [Ir-Hf]/HfLaO CMOS Using Novel Self-Aligned Low Temperature Shallow Junctions

We report very low V_t [Ir-Hf]/HfLaO CMOS using novel self-aligned low-temperature ultra shallow junctions with gate-first process compatible with current VLSI. At 1.2 nm EOT, good Phi_m-eff of 5.3 and 4.1 eV, low V_t of +0.05 and 0.03 V, high mobility of 90 and 243 cm²/Vs, and small 85degC BTI <32 mV (10 MV/cm, 1 hr) are measured for p- and n-MOS.

A Low Operating Voltage ZnO Thin Film Transistor Using a High- κ HfLaO Gate Dielectric

This study demonstrates the feasibility of producing a ZnO thin film transistor (TFT) using hafnium-lanthanum-oxide (HfLaO) as the gate dielectric. By integrating high-κ HfLaO with an amorphous ZnO channel, the resulting HfLaO/ZnO TFTs display a low threshold voltage (V T ) of 0.28 V, a small subthreshold swing (SS) of 0.26 V/dec, an acceptable mobility (μ sat ) of 3.5 cm 2 /V s, and a good I on/ I off ratio of I × 10 6 . The SS heavily depends on the HfLaO/ZnO interface charges, a property which is related to the degree of crystallization of ZnO. The low V T and the small SS allow device voltage operation below 2 V for low power application.

High-Work-Function Ir/HfLaO

We report a high effective work function (Phim-eff) and a very low Vt Ir gate on HfLaO p-MOSFETs using novel self-aligned low-temperature shallow junctions. This gate-first process has shallow junctions of 9.6 or 20 nm that are formed by solid phase diffusion using SiO2-covered Ga or Ni/Ga. At 1.2-nm effective oxide thickness, good Phim-eff of 5.3 eV, low Vt of +0.05 V, high mobility of 90 cm2/V-s at -0.3 MV/cm, and small 85degC negative bias-temperature instability (NBTI) of 20 mV (10 MV/cm for 1 h) are measured for Ir/HfLaO p-MOSFETs.

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Thin-film transistors were fabricated using amorphous indium gallium zinc oxide (α-IGZO) as channels and high-к material HfSiO as gate dielectric by RF sputtering. The influence of high-к PDA temperature variation on device characteristics was investigated. The bottom-gate low voltage driven (≤ 2 V) TFTs operated in n-type enhancement mode with a field-effect mobility of 12.7cm²/V-s, on-off current ratio of 3×10⁵, threshold voltage of 0.005V, and subthreshold voltage swing of 0.11V/dec.

-MOSFETs Using Low-Temperature-Processed Shallow Junction

At a 1.2-nm equivalent oxide thickness, HfSi_x/Hf_0.7La_0.3ON n-MOSFETs showed an effective work function of 4.33 eV, a low threshold voltage of 0.18 V, and a peak electron mobility of 215 cm²/(Vldrs). These self-aligned and gate-first HfSi_x/Hf_0.7La_0.3ON n-MOSFETs were processed using standard ion implantation and 1000-degC rapid thermal annealing, making them fully compatible with current very large scale integration fabrication lines.

High performance and low driving voltage amorphous InGaZnO thin-film transistors using high-к HfSiO dielectrics

In this study, we demonstrate the role of a titanium hafnium oxide (TiHfO) gate dielectric in improving the overall electronic performance of a ZnO thin-film transistor (TFT). TixHf1-xO (x = 0.63) was fabricated by the rf co-sputtering technique. Using TiHfO as the gate dielectric, the device fabricated in this study exhibits a threshold voltage of 0.34 V, a subthreshold swing of 0.23 V/dec, a field-effect mobility of 2.1 cm2 V-1 s-1, and an ON/OFF current ratio of 105. The small subthreshold swing and low positive threshold voltage are attributed to the higher value of ? of 40 for the dielectric. This result enables device operation below 2 V, allowing its use in low-power driving circuits in display applications.

HfLaON n-MOSFETs Using a Low Work Function

Using excimer laser annealing and laser-reflective Al-covered gate, the self-aligned, gate-dielectric first and gate-electrode first Al/TaN/Ir/HfLaO p-MOSFET showed low threshold voltage (Vt) of -0.07 V and good peak hole mobility of 86 cm2/V-s at 1.5 nm equivalent-oxide thickness (EOT).