隨著數十年的發展，元件尺寸越來越接近物理極限，摩爾定律可能因此失效，半導體產業的發展也可能趨於平緩，此時元件結構的改變以及替代材料的研發就變得極為重要。2D材料因為其特殊的結構以及優秀的電性受到關注，其中的過渡金屬二硫族化物(TMDs)因為其原子級別厚度、無缺陷、在極小元件尺寸的適配性與不受短通道效應影響的特點，使得過渡金屬二硫族化物在半導體產業的應用備受期待。
本研究透過不同條件的微波退火、快速熱退火與合成氣體退火等處理方式，觀察後退火製程對背向閘極之二硫化鉬電晶體的影響。並藉由電性量測與電流開關比、臨界電壓、次臨界擺幅、載子遷移率與接觸電阻等參數萃取推斷出不同後退火製程在改善元件特性方面的表現。經過微波退火處理後的元件開關特性在最好的情況下可以提升至106，載子遷移率在經過不同功率的微波退火後接可提升至10-1〖cm〗^2/ V*s，並且接觸電阻下降至接近10kΩ-µm左右。雖然相比於目前2D材料元件最低的接觸電阻123Ω-µm仍然有相當大的差距，但還是有一定程度的改善。較高溫度下的快速熱退火因為雜質的過度擴散導致隊元件特性的改善效果相對有限。較低溫度的合成氣體退火對於元件特性的改善效果也相對不足，然而，不同溫度的合成氣體退火皆使得元件的臨界電壓產生正向偏移。另外，本研究也探討了化學氣相沉積(CVD)在晶圓上沉積二硫化鉬的均勻度對元件特性的影響，並比較經過後退火製程前後的變化。除此之外，也探討不同退火時間的微波退火對於元件特性的影響，長時間的微波退火導致原本修復的晶格結構再度被破壞，大幅度抑制了對元件特性的改善。最後，透過X射線光電子能譜儀(XPS)分析經過微波退火後的元件表面元素組成和化學鍵結狀況，得知微波退火有助於修復元件表面的晶格結構。

With decades of development, the size of semiconductor devices is approaching physical limits, potentially leading to the end of Moore's Law and a slowdown in the advancement of the semiconductor industry. At this point, changes in device structure and the development of alternative materials become crucial. Two-dimensional (2D) materials have attracted significant attention due to their unique structures and excellent electrical properties. Among them, transition metal dichalcogenides (TMDs) are particularly promising for the semiconductor industry. Their atomic-scale thickness, defect-free nature, compatibility with extremely small device sizes, and immunity to short-channel effects make TMDs highly anticipated for applications in the semiconductor industry.
This study investigates the effects of post-annealing processes on back-gate MoS2 transistors using different conditions of microwave annealing (MWA), rapid thermal annealing (RTA), and forming gas annealing (FGA). Electrical measurements, including current on/off ratio, threshold voltage, subthreshold swing, carrier mobility, and contact resistance, were utilized to evaluate and infer the performance of different post-annealing processes in improving device characteristics.
Devices treated with MWA exhibited an improvement in switching characteristics, achieving a current on/off ratio of up to 106 in the best case. Carrier mobility increased to approximately 10-1〖cm〗^2/ V*s after MWA at different power levels, and contact resistance decreased to around 10kΩ-µm. Although there is still a considerable gap compared to the lowest reported contact resistance of 123 Ω-µm in current 2D material devices, a certain degree of improvement has been achieved. The effect of high-temperature RTA on device improvement was limited due to excessive impurity diffusion. Similarly, low-temperature FGA was relatively insufficient in improving device characteristics, however, it caused a positive shift in the threshold voltage at all temperatures tested.
Additionally, this study examined the impact of the uniformity of MoS2 deposition on the wafer by chemical vapor deposition (CVD) on device performance, comparing changes before and after post-annealing processes. The influence of different MWA durations on device characteristics was also explored, revealing that prolonged MWA led to the re-damage of previously repaired lattice structures, significantly hindering device improvement.
Finally, X-ray photoelectron spectroscopy (XPS) was used to analyze the surface elemental composition and chemical bonding states of devices post-MWA, confirming that MWA aids in repairing the lattice structure on the device surface.

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