2017年第78回応用物理学会秋季学術講演会

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一般セッション(口頭講演)

13 半導体 » 13.5 デバイス/集積化技術

[8a-C18-1~12] 13.5 デバイス/集積化技術

6.1と13.3と13.5のコードシェアセッションあり

2017年9月8日(金) 09:00 〜 12:15 C18 (C18)

西村 知紀(東大)、森 貴洋(産総研)

11:45 〜 12:00

[8a-C18-11] Variability Characterictics of Gate-All-Around Polycrystalline Silicon Nanowire Transistors with 10nm-Scale Width

Kihyun Jang1、Takuya Saraya1、Masaharu Kobayashi1、Naomi Sawamoto2、Atsushi Ogura2、Toshiro Hiramoto1 (1.The University of Tokyo、2.Meiji University)

キーワード:Gate-All-Around, Polycrystalline Silicon Nanowire, Variability Characterictics

[Introduction] Poly-Si nanowire (NW) transistors have attracted attention for 3D multilayer stack integrated circuits and NAND flash memory applications [1]. Most of reported poly-Si NW transistors have width larger than 30nm but few transistors with width of 10nm scale have been reported. In this work, GAA poly-Si NW transistors with 10nm scale width have been fabricated in very controllable manner using electron-beam (EB) lithography. The variability characteristics of threshold voltage (Vth) and drain current (Id) are evaluated [2].
[Fabrication] The EB conditions were carefully optimized so that the actual NW width just after RIE (before gate oxidation) is the same as design width (Wd). Fig. 1 shows cross-section TEM images of a fabricated NW transistor. The trapezoid-shaped GAA structure is confirmed. The width of top and bottom are ~5nm and 15nm, respectively.
[Results] Fig. 2 shows I-V characteristics of a planar transistor and the NW transistor (Wd=15nm, L=300nm, the specific transistor whose cross-section is shown in Fig. 1). In the NW transistor, electrical properties are improved because the total number of grain boundaries and traps are reduced by scaling poly-Si film. Fig. 3 shows variability characteristics. To make a fair comparison with reported data [3], the Pelgrom plot is shown in Fig. 4. σVth/Tinv is evaluated to cancel the effect of Tinv for Vth variability [3] and overdrive voltage (Vg–Vth) is fixed for Id variability [3]. Smaller or comparable variability than that of reported poly-Si NW transistors [3] is confirmed.
[Summary] GAA Poly-Si NW transistors with width of 10 nm scale were fabricated under precise width control and small variability is confirmed.