Browsing by Author "Shen, SW"

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A novel methodology for extracting effective density-of-states in poly-Si thin-film transistors
(2004)
Lin, HC
;
Yeh, KL
;
Lee, MH
;
Su, YC
;
Huang, TY
A novel methodology that greatly simplifies the procedure of extracting the effective density-of-states (DOS) in polycrystalline-Si thin-film transistors (poly-Si TFTs) is proposed and demonstrated. The characterization is performed on a Schottky barrier (SB) TFT with electrical source/drain extensions induced by a field-plate. Only one single device and two simple subthreshold I-V measurements at room temperature are needed for full band-gap DOS extraction. Impacts of different process treatments are clearly resolved using this methodology.
Improvements on electrical characteristics of p-channel metal-oxide-semiconductor field effect transistors with HfO(2) gate stacks by post deposition N(2)O plasma treatment
(2005-11-01)
Lu, WT
;
Chien, CH
;
Lan, WT
;
Lee, TC
;
Yang, MJ
In this work, we found that employing a post deposition N(2)O plasma treatment following the deposition of HfO(2) film can effectively improve the electrical characteristics of p-type channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with a HfO(2) gate stack in terms of lower gate leakage current, lower interface state density, superior subthreshold swing, higher normalized transconductance and enhanced driving current even though it had led to a slightly higher equivalent oxide thickness (EOT) value of the HfO(2) gate stack by around 0.3 nm. In order to clarify the attributes of the improvements, we used charge pumping (CP) measurement to analyze the densities of interface states and bulk traps in the HfO(2) gate stacks. The improvements are then ascribed to the higher interface quality offered by the post deposition N(2)O plasma treatment. Moreover, we found that to more accurately estimate the bulk traps from the CP measurement, the leakage should be taken into account especially at low frequencies. Finally, it was found that the levels of the bulk traps and interface states can be reduced by the N(2)O plasma treatment, which also helps significantly eliminate the degradation of the gate stack during the subsequent voltage stress.
Improvements on electrical characteristics of p-channel metal-oxide-semiconductor field effect transistors with HfO2 gate stacks by post deposition N2O plasma treatment
(2005-11-01)
Lu, WT
;
Chien, CH
;
Lan, WT
;
Lee, TC
;
Yang, MJ
In this work, we found that employing a post deposition N2O plasma treatment following the deposition of HfO2 film can effectively improve the electrical characteristics of p-type channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with a HfO2 gate stack in terms of lower gate leakage current, lower interface state density, superior subthreshold swing, higher normalized transconductance and enhanced driving current even though it had led to a slightly higher equivalent oxide thickness (EOT) value of the HfO2 gate stack by around 0.3 nm. In order to clarify the attributes of the improvements, we used charge pumping (CP) measurement to analyze the densities of interface states and bulk traps in the HfO2 gate stacks. The improvements are then ascribed to the higher interface quality offered by the post deposition N2O plasma treatment. Moreover, we found that to more accurately estimate the bulk traps from the CP measurement, the leakage should be taken into account especially at low frequencies. Finally, it was found that the levels of the bulk traps and interface states can be reduced by the N2O plasma treatment, which also helps significantly eliminate the degradation of the gate stack during the subsequent voltage stress.
Low-temperature growth of polycrystalline ge films on SiO2 substrate by HDPCVD
(2005)
Yang, MJ
;
Shieh, J
;
Hsu, SL
;
Huang, IJ
;
Leu, CC
Pure and high-quality polycrystalline Ge films have been deposited directly onto fully SiO2 covered substrates by high-density plasma chemical vapor deposition (HDPCVD) system. Only a tiny amount of O and C near the surface has been observed from X-ray photoelectron spectroscopy and Auger electron spectroscopy data, which may come from surface oxidation and contamination. Very pure Ge composition has been achieved in the bulk of the films. The cubic structure with primarily (111), (220), and (311) orientations of the Ge films is mainly composed of fine grains and can be unambiguously identified from X-ray diffraction patterns. Furthermore, successful Ge film depositions with nearly no incubation time are demonstrated using a mixture of GeH4/H-2 as process gas at 400 degrees C. Thickness vs. time analysis was performed by high-resolution transmission electron microscopy. The HDPCVD technique used was able to provide a simple, powerful, and reliable approach in the fabrication of polycrystalline Ge thin film transistors. (C) 2005 The Electrochemical Society.
Study of thermal stability of nickel monogermanide on single- and polycrystalline germanium substrates
(2005-06-20)
Hsu, SL
;
Chien, CH
;
Yang, MJ
;
Huang, RH
;
Leu, CC
We have investigated the thermal stability of nickel monogermanide (NiGe) films formed by rapid thermal annealing on both single- and polycrystalline Ge substrates. We found that the NiGe phase is the only one present after nickel germanidation in the temperature range 400-700 degrees C. A fairly uniform NiGe film formed on the single-crystalline Ge; it possessed excellent resistivity (15.6 mu Omega cm) and was thermally stable up to 550 degrees C, but it degraded rapidly at higher temperatures as a result of agglomeration. In contrast, the NiGe film formed on the polycrystalline Ge exhibited much poorer thermal stability, possibly because of polycrystalline Ge grain growth, which resulted in columnar NiGe grains interlaced with Ge grains that had a dramatically increased sheet resistance. As a result, we observed that the sheet resistances of NiGe lines subjected to annealing at 500 degrees C depended strongly on the linewidth when this width was comparable with the grain size of the polycrystalline Ge. (c) 2005 American Institute of Physic's.