Browsing by Author "Chi, Wei-Chun"

Now showing 1 - 4 of 4

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.
High Performance Ge Schottky PMOSFETs with Ternary-Phase Alloy
(2016-01-01)
Hsu, Chung-Chun
;
Chi, Wei-Chun
;
Chou, Chen-Han
;
Chen, Che-Wei
;
Chien, Hung-Pin
This work demonstrates high-performance Ge p-channel metal-oxide-semiconductor field-effect transistors (PMOSFETs) [1] with ternary-phase NiGePt alloy Schottky source/drain (S/D) by low-temperature microwave-activated annealing (MWA) [2]. Process flow of Shcottky junctions is shown in Fig. 1. Interestingly, the formed NiGePt alloy is nearly single crystalline. We found the formation of ternary-phase alloy NiGePt seems very helpful in suppressing the off-leakage of junction, as shown in Fig. 2. The fabricated NiGePt/N-Ge Schottky junction depicted an impressive effective barrier height (Phi(Bn)) of similar to 0.59 eV for electrons, leading to a high junction current ratio of >10(5) at the applied voltage of vertical bar V-a vertical bar = 1 V. Slight increase with increasing deposited Pt thickness can be explained by the improved series resistance, as shown in Fig. 2. The lower process temperature of MWA as compared to the conventional thermal annealing is beneficial for eliminating surface roughness, reducing alloy agglomeration of Schottky contact S/D. As a consequence, we employed the advantages of low-temperature MWA to fabricate the Schottky S/D PMOSFETs. With forming gas annealing, the Ge PMOSFET (L = 4 mu m) showed a very high output current of 33.5 mu A/mu m at V-GS-V-T = -2.4 and V-DS = -2 V. Our ternary Schottky PMOSFET exhibited a high I-ON/I-OFF ratios of similar to 3.7 X 10(3)(I-D) and similar to 1.3 X 10(5)(I-S), and a moderate subthreshold swing of 126 mV/dec, as shown in Figs. 3.
Integration of microwave-annealed oxidation on germanium metal-oxide-semiconductor devices
(2018-09-01)
Hsu, Chung-Chun
;
Chi, Wei-Chun
;
Tsai, Yi-He
;
Tsai, Ming-Li
;
Wang, Shin-Yuan
In this paper, a method that entails using microwave thermal oxidation to form a high-quality gate dielectric on Ge through surface passivation at considerably low temperatures (<400 degrees C) is presented. Formation of the GeOx layer was confirmed by x-ray photoelectron spectroscopy. To reduce the bulk trap density and interface trap density (D-it), microwave thermal oxidation was employed for post-deposition microwave thermal oxidation after the deposition of Al2O3 through atomic layer deposition. Tiny frequency dispersion in capacitance measurement and a low D-it value of 5.9 x 10(11) cm(-2) eV(-1) near the midgap confirmed a desirable passivation effect, which was favorable in mitigating the formation of dangling bonds on the Ge surface. A small hysteresis in capacitance was also observed, suggesting that the bulk dielectric was of high quality. On the basis of these characteristics, microwave-activated GeOx is a promising passivation layer material for aggressively scaled Ge-related metal oxide semiconductor devices. Published by the AVS.
Phase-separation phenomenon of NiGePt alloy on n-Ge by microwave annealing
(2018-04-30)
Hsu, Chung-Chun
;
Lin, Kun-Lin
;
Chi, Wei-Chun
;
Chou, Chen-Han
;
Luo, Guang-Li
During the formation of distinct bilayer NiGePt alloy, a phase-separation phenomenon was observed using microwave annealing and structural engineering. The microstructures of bilayer NiGePt [PtGe(Ni)-NiGe(Pt)] alloys fabricated with 10-nm Ni and various thicknesses of Pt (5, 10, and 15 nm) were characterized. Within the same thermal budget as microwave annealing, the diffusion of Ni exhibited stronger alloy formation ability with Ge and drilled through the Pt layer without resistance. The higher diffusivity of Ni atoms dominated the diffusion of Ni through the Pt layer to form a stable crystalline layer, NiGe(Pt). Ge diffused outwardly toward the Pt layer to form a PtGe(Ni) layer. This special phenomenon of bilayer alloy formation was elucidated using nanobeam electron diffraction by transmission electron microscopy in conjunction with energy-dispersive spectrometry. Comparing the differences in metal alloys between microwave and rapid thermal annealing, microwave annealing formed a bilayer alloy more apparently than rapid thermal annealing. The results and electrical characteristics indicated that a thicker Pt layer for forming a bilayer NiGePt alloy with alloy separation could also effectively improve the leakage current of NiGePt [PtGe(Ni)- NiGe(Pt)]/n-Ge Schottky junctions. (c) 2018 Elsevier B.V. All rights reserved.