Browsing by Author "Noda, Shuichi"

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AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications
(2016-11)
Lin, Yen-Ku
;
Noda, Shuichi
;
Lo, Hsiao-Chieh
;
Liu, Shih-Chien
;
Wu, Chia-Hsun
The electrical performances of gate-recessed AlGaN/GaN high-electron mobility transistors (HEMTs) fabricated using the damage-free neutral beam etching (NBE) method are demonstrated. The NBE method could eliminate the plasma-induced defects generated by irradiating ultraviolet/VUV photons in the conventional inductively coupled plasma reactive ion etching method. The AlGaN/GaN HEMT device fabricated using the new gate recess process exhibited superior electrical performances, including a maximum drain current density (I-DS,I-max) of 1.54 A/mm, low 1/f noise, a current-gain cutoff frequency (f(T)) of 153 GHz, a maximum frequency of oscillation (f(MAX)) of 167 GHz, and a minimum noise figure (NFmin) of 3.28 dB with an associated gain (G(AS)) of 5.06 dB at 54 GHz. Such superior characteristics confirm the inherent advantages of adopting the damage-free NBE process in fabricating GaN devices for millimeter-wave applications.
AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications (vol 37, pg 1395, 2016)
(2017-01)
Lin, Yen-Ku
;
Noda, Shuichi
;
Lo, Hsiao-Chieh
;
Liu, Shih-Chien
;
Wu, Chia-Hsun
AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications (vol 37, pg 1395, 2016)
(2017-01)
Lin, Yen-Ku
;
Noda, Shuichi
;
Lo, Hsiao-Chieh
;
Liu, Shih-Chien
;
Wu, Chia-Hsun
Atomic layer defect-free etching for germanium using HBr neutral beam
(2019-09-01)
Fujii, Takuya
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Ohori, Daisuke
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Noda, Shuichi
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Tanimoto, Yosuke
;
Sato, Daisuke
The authors developed extremely selective etching for making an atomically flat, defect-free germanium fin (Ge Fin) structure. The etching uses a hydrogen bromide (HBr) neutral beam (NB), and they investigated the etching reaction differences between the HBr NB and a Cl-2 NB. No sidewall etching by HBr NB occurred at 90 degrees C, although that by Cl-2 NB occurred at more than 90 degrees C. This was due to the different boiling points of GeBr4 and GeCl4 as the reacted layer was formed by NB irradiation on the Ge surface. As a result, the Ge sidewall etching by Cl-2 NB occurred above 90 degrees C, whereas that by HBr NB did not occur at 90 degrees C. Additionally, nonvolatile bromide protected layers, such as GeBr4 and SiBrxOy, were deposited on the Ge sidewall and the SiO2 top surface in case of using HBr, respectively. Then, the authors succeeded in fabricating the atomically flat, defect-free Ge Fin structure with the extremely selective HBr NB etching. This result shows that HBr NB can more precisely achieve sub-10-nm scale atomic layer Ge etching for 3D Fin-type MOSFETs.
Atomic layer germanium etching for 3D Fin-FET using chlorine neutral beam
(2019-03-01)
Ohori, Daisuke
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Fujii, Takuya
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Noda, Shuichi
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Mizubayashi, Wataru
;
Endo, Kazuhiko
In case of using pure chlorine chemistry, Ge etching reactivity is three times higher than Si etching reactivity because of the larger lattice spacing in Ge. As a result, during the chlorine plasma etching of a Ge Fin structure, there are serious problems such as a large side-etching and large surface roughness on the Ge sidewall. Conversely, the authors found that several-ten nanometer-width Ge Fin structures with defect-free, vertical, and smooth sidewalls were successively delineated by chlorine neutral beam etching. Based on these results, the problems caused by chlorine plasma etching are considered to be due to the enhancement of chemical reactivity caused by defect on the sidewall with the irradiation of ultraviolet/vacuum ultra violet (UV/VUV) photons. Namely, it is clarified that the neutral beam etching could achieve real atomic layer etching by controlling the defect without any UV/VUV photons on the sidewall surface for future nanoscale Ge Fin structures. Published by the AVS.
Enhancement-mode AlGaN/GaN MIS-HEMTs with Low Threshold Voltage Hysteresis Using Damage-free Neutral Beam Etched Gate Recess
(2016)
Lin, Yen-Ku
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Noda, Shuichi
;
Lee, Ruey-Bor
;
Huang, Chia-Ching
;
Quang Ho Luc
An enhancement- mode AlGaN/GaN MIS-HEMTs with low threshold voltage hysteresis using damage-free neutral beam etched (NBE) gate recess is reported. The NBE can eliminate the plasma-induced defects that generated by irradiating UV/VUV photons as encounted in the conventional inductively coupled plasma-reactive-ion etching (ICP-RIE). Combining the new gate recess process and PEALD-AlN interfacial passivation layer, the Al2O3/AlGaN/GaN enhancement- mode HEMT device shows a threshold voltage of 1.5 V and a current density of 449 mA/mm, and the three-terminal breakdown voltage was 432 V. The device also shows small hysteresis in threshold voltage at stable I-V curve.
High-Performance GaN MOSHEMTs Fabricated With ALD Al2O3 Dielectric and NBE Gate Recess Technology for High Frequency Power Applications
(2017-06-01)
Lin, Yen-Ku
;
Noda, Shuichi
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Huang, Chia-Ching
;
Lo, Hsiao-Chieh
;
Wu, Chia-Hsun
High-performance GaN metal-oxidesemi-conductor high-electron-mobility transistors (MOSHEMTs) using Al2O3 gate dielectric deposited by atomic layer deposition (ALD) and damage-free neutral beam etch (NBE) gate recess process for millimeter-wave power applications are demonstrated. The high-quality ALD Al2O3 reduces the gate leakage current of the device and the NBE method eliminates the plasma-induced defects in the nitride materials. The MOSHEMT device fabricated exhibits a high maximum drain current density (I-DS,I-max ) of 1.65 A/mm and a high peak extrinsic transconductance (g(m.ext) ) of 653 mS/mm. The MOSHEMT device also demonstrates excellent RF performances, including f(T)/f(MAX) = 183/191 GHz, NFmin = 2.56 dB with G(AS) = 5.61 dB at 54 GHz, and an output power density of 2.7 W/mm associated with a power-added efficiency of 20.9% and a linear power gain of 9.4 dB at 38 GHz. To the best of our knowledge, the noise performance at 54 GHz is the best reported so far for the AlGaN/GaN HEMTs.
Impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and device performance of Ge fin field-effect transistors
(2017-02-01)
Mizubayashi, Wataru
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Noda, Shuichi
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Ishikawa, Yuki
;
Nishi, Takashi
;
Kikuchi, Akio
We investigated the impacts of plasma-induced damage due to UV light irradiation during etching on Ge fin fabrication and the device performance of Ge fin field-effect transistors (Ge FinFETs). UV light irradiation during etching affected the shape of the Ge fin and the surface roughness of the Ge fin sidewall. A vertical and smooth Ge fin could be fabricated by neutral beam etching without UV light irradiation. The performances of Ge FinFETs fabricated by neutral beam etching were markedly improved as compared to those of Ge FinFETs fabricated by inductively coupled plasma etching, in which the UV light has an impact. (C) 2017 The Japan Society of Applied Physics