Browsing by Author "Chuang, Shang-Shiun"

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Diamond-shaped Ge and Ge0.9Si0.1 Gate-All-Around Nanowire FETs with Four {111} Facets by Dry Etch Technology
(2015)
Lee, Yao-Jen
;
Hou, Fu-Ju
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Chuang, Shang-Shiun
;
Hsueh, Fu-Kuo
;
Kao, Kuo-Hsing
We propose a feasible pathway to scale the Ge MOSFET technology by using a novel diamond-shaped Ge and Ge0.9Si0.1 gate-all-around (GAA) nanowire (NW) FETs with four {111} facets. The device fabrication requires only simple top-down dry etching and blanket Ge epitaxy techniques readily available in mass production. The proposed dry etching process involves three isotropic/anisotropic etching steps with different Cl-2/HBr ratios for forming the suspended diamond-shaped channel. Taking advantages of the GAA configuration, favorable carrier mobility of the {111} surface, nearly defect-free suspended channel, and improved dopant activation by incorporating Si, nFET and pFET with excellent performance have been demonstrated, including an I-on/I-off ratio exceeding 10(8), the highest ever reported for Ge-based pFETs.
Dopant Activation in Single-Crystalline Germanium by Low-Temperature Microwave Annealing
(2011-02-01)
Lee, Yao-Jen
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Chuang, Shang-Shiun
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Hsueh, Fu-Kuo
;
Lin, Ho-Ming
;
Wu, Shich-Chuang
Phosphorus activated in germanium epitaxy atop Si wafer by low-temperature microwave annealing technique was investigated in this letter. Compared to the conventional RTA process, the temperature of phosphorus activation could be 120 degrees C to 140 degrees C which is an improvement in temperature reduction at the same sheet resistance. According to the SRP, up to 150 degrees C reduction in maximum temperature at the same activation concentration (about 2 x 10(19) cm(-3)) could be achieved. Through adjusting the microwave power and process time, sheet resistance could be decreased while suppressing dopant diffusion. In addition, the inserted susceptor wafers above and below the processing wafer also suppressed the dopant diffusion and improved film roughness.
Experimental Realization of a Ternary-Phase Alloy Through Microwave-Activated Annealing for Ge Schottky pMOSFETs
(2016-07)
Hsu, Chung-Chun
;
Chi, Wei-Chun
;
Tsai, Yi-He
;
Chou, Chen-Han
;
Chen, Che-Wei
This paper presents a high-performance Ge p-channel MOSFET (pMOSFET) with NiGePt as a ternary-phase alloy of Schottky source/drain (S/D) formed through low-temperature microwave-activated annealing (MWA). We fabricated a NiGePt alloy contact with uniform crystallinity through structural engineering and MWA. We clarified the phenomena of thermal reaction and diffusion for forming ternary-phase alloys using MWA properties such as thermal dynamics and ionic transportation. The ternary-phase NiGePt alloy is crucial for improving the off-leakage current of the junction. A lower process temperature is beneficial for eliminating surface roughness and reducing alloy agglomeration of the Schottky contact S/D. Consequently, the fabricated NiGePt/n-Ge Schottky junction exhibited a high effective barrier height (Phi(Bn)) of 0.59 eV, resulting in a high junction current ratio of more than 10(5) at an applied voltage of vertical bar V-a vertical bar = 1 V. In addition, we exploited the advantages of low-temperature microwave annealing to fabricate the pMOSFET, which includes a GeO2 passivation layer and a Schottky S/D. Our ternary Schottky Ge pMOSFET (L = 4 mu m) exhibited high I-ON/I-OFF ratios of approximately 3.7x10(3)(I-D) and 1.3x10(5)(I-S) and a moderate subthreshold swing of 126 mV/dec.
Low-Temperature Microwave Annealing Processes for Future IC Fabrication-A Review
(2014-03-01)
Lee, Yao-Jen
;
Cho, Ta-Chun
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Chuang, Shang-Shiun
;
Hsueh, Fu-Kuo
;
Lu, Yu-Lun
Microwave annealing (MWA) and rapid thermal annealing (RTA) of dopants in implanted Si are compared in their abilities to produce very shallow and highly activated junctions. First, arsenic (As), phosphorus (P), and BF2 implants in Si substrate were annealed by MWA at temperatures below 550 degrees C. Next, enhancing the substitutional carbon concentration ([C] sub) by cluster carbon implantation in (100) Si substrates with MWA or RTA techniques was investigated. Annealing temperatures and time effects were studied. Different formation mechanisms of SiCx layer were observed. In addition, substrate temperature is an important factor for dopant activation during MWA and in situ doped a-Si on oxide/Si substrate or glass were compared to elucidate the substrate temperature effect. After the discussion of dopant activation in Si substrates, low temperature formation of ultrathin NiGe layer is presented. Ultrathin NiGe films with low sheet resistance have been demonstrated with a novel two-step MWA process. In the two-step MWA process, the first step anneals the sample with low power MWA, and the second step applies higher power MWA for reducing sheet resistance. During fixed-frequency microwave heating, standing wave patterns may be present in the MWA chamber resulting in nodes and antinodes and thermal variations over the process wafer. Therefore, the effects of Si or quartz susceptor wafers on dopant activation and sheet resistance uniformity during fixed-frequency MWA were investigated.
Solid Solubility Limited Dopant Activation of Group III Dopants (B, Ga & In) in Ge Targeting sub-7nm Node Low p plus Contact Resistance
(2017-01-01)
Borland, John
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Lee, Yao-Jen
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Chuang, Shang-Shiun
;
Tseng, Tseung-Yuen
;
Liu, Chee-Wee
Ultra-Shallow Junction Formation by Monolayer Doping Process in Single Crystalline Si and Ge for Future CMOS Devices
(2017-01-01)
Chuang, Shang-Shiun
;
Cho, Ta-Chun
;
Sung, Po-Jung
;
Kao, Kuo-Hsing
;
Chen, Henry J. H.
We focused on the damage-free monolayer doping (MLD) method starting from a chemical reaction of molecules on Si and Ge surfaces and applied it to 3D MOSFET device fabrication. MLD methods were verified by different material analysis, such as XPS and Raman spectroscopy. For a Si-based FinFET structure, compared to the device with ion implantation, the short channel effect of source and drain (SD) extension regions formed by MLD are improved. The shallower SD extension regions formed by low-temperature microwave annealing (MWA) are expected to the device showing better electrical properties than deeper ones formed by RTA. In addition, formation of the n- and p-type doping in Ge by MLD was also investigated. Even after annealing at 800 degrees C for 300 sec by RTA, the p-type doping still exhibits a low surface doping concentration due to the low diffusion coefficient of B in Ge and surface diffusion limitations at the MLD/Ge interface. By using a combination of RTA and CO2 laser spike annealing (LSA), MLD n-type doping in Ge are formed with junction depths of approximate to 15 nm, and peak concentration of approximate to 6 x 10(20) atoms/cm(3). The dopant activation for the MLD-doped channels of Ge junctionless FinFETs (JLFinFETs) is improved after the additional CO2 LSA. (C) 2017 The Electrochemical Society. All rights reserved.