Experimental Realization of a Ternary-Phase Alloy Through Microwave-Activated Annealing for Ge Schottky pMOSFETs

• Published in: IEEE transactions on electron devices Vol. 63; no. 7; pp. 2714 - 2721
• Main Authors: Hsu, Chung-Chun, Chi, Wei-Chun, Tsai, Yi-He, Chou, Chen-Han, Chen, Che-Wei, Chien, Hung-Pin, Chuang, Shang-Shiun, Luo, Guang-Li, Lee, Yao-Jen, Chien, Chao-Hsin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Agglomeration; Alloy development; Alloys; Annealing; Contact; Crystallinity; Devices; Electric potential; Germanium oxides; Junctions; microwave-activated annealing (MWA); MOSFET; MOSFETs; Nickel; NiGePt; p-channel MOSFET (pMOSFET); Schottky barrier height (SBH); Surface morphology; ternary-phase alloy; Thermal stability; p-channel MOSFET (pMOSFET); ternary-phase alloy; Crystallinity; Schottky barrier height (SBH); microwave-activated annealing (MWA); NiGePt
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2016.2570284

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 (ΦBn) of 0.59 eV, resulting in a high junction current ratio of more than 10 5 at an applied voltage of |V a | = 1 V. In addition, we exploited the advantages of low-temperature microwave annealing to fabricate the pMOSFET, which includes a GeO 2 passivation layer and a Schottky S/D. Our ternary Schottky Ge pMOSFET (L = 4μm) exhibited high I ON /I OFF ratios of approximately 3.7 × 10 3 (I D ) and 1.3 × 10 5 (I S ) and a moderate subthreshold swing of 126 mV/dec.