Browsing by Author "Yeo, YC"

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Electron mobility in Ge and strained-Si channel ultrathin-body metal-oxide semi conductor field-effect transistors
(2004-09-20)
Low, T
;
Li, MF
;
Shen, C
;
Yeo, YC
;
Hou, YT
Electron mobility in strained silicon and various surface oriented germanium ultrathin-body (UTB) metal-oxide semiconductor field-effect transistors (MOSFETs) with sub-10-nm-body thickness are systematically studied. For biaxial tensile strained-Si UTB MOSFETs, strain effects offer mobility enhancement down to a body thickness of 3 nm, below which strong quantum confinement effect renders further valley splitting via application of strain redundant. For Ge channel UTB MOSFETs, electron mobility is found to be highly dependent on surface orientation. Ge<100> and Ge<110> surfaces have low quantization mass that leads to a lower mobility than that of Si in aggressively scaled UTB MOSFETs. (C) 2004 American Institute of Physics.
Formation of dual-phase HfO2-HfxSi1-xO2 dielectric and its application in memory devices
(2005-07-01)
Wang, YQ
;
Chen, JH
;
Yoo, WJ
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Yeo, YC
;
Yeo, YC
In this paper, we studied the phase-separation phenomenon of Hf0.5Si0.5O2 film deposited on SiO2 or sandwiched by SiO2, by x-ray photoelectron spectroscopy and transmission electron microscopy. The Hf0.5Si0.5O2 film underwent phase separation to form a doublet-phase HfO2-HfxSi1-xO2 (x < 0.5) film, and was used as a trapping layer in a metal-blocking oxide-silicon nitride-tunnel oxide-silicon-type memory structure, where the dual-phase HfO2-HfxSi1-xO2 (DPHSO) film replaces the conventional silicon nitride (Si3N4) trapping layer. The charge storage properties of the DPHSO film were investigated and compared with HfO2 and Si3N4. It was found that for a given electric field applied to the tunnel oxide, the programming speed of memory devices using a DPHSO or HfO2 film as a trapping layer is faster than that using SiA. This indicates the higher electron-capture efficiency of the DPHSO and HfO2 films. In addition, the double-phase microstructure of the DPHSO film also provided better retention property than pure HfO2. (c) 2005 American Institute of Physics.
Fully silicided NiSi gate on La2O3 MOSFETs
(2003-05-01)
Lin, CY
;
Ma, MW
;
Chin, A
;
Yeo, YC
;
Zhu, CX
We have fabricated the fully silicided NiSi on La2O3 for n- and p-MOSFETs. For 900 degreesC fully silicided CoSi2 on La2O3 gate dielectric with 1.5 mn EOT, the, gate dielectric has large leakage current by possible excess Co diffusion at high silicidation temperature. In sharp contrast, very low gat e leakage current density of 2 x 10(-4) A/cm(2) at 1 V is measured for 400 degreesC formed fully silicided NiSi and comparable with Al gate. The extracted work function of NiSi was 4.42 eV, and the corresponding threshold voltages are 0.12 and -0.70 V for respective n- and p-MOSFETs. Electron and hole mobilities of 156 and 44 cm(2)/V-s are obtained for respective n- and p-MOSFETs, which are comparable with the HfO2 MOSFETs without using H-2 annealing.