本論文旨在探討將高熵合金材料應用於金屬-氧化物-半導體電容器金屬層之特性，利用電性與材料分析的方法研究金屬與氧化層介面氧化與擴散行為。研究的材料系統包括NbMoTaW、Nb0.15Mo0.15Ta0.35W0.35、Nb0.15Mo0.35Ta0.15W0.35、NbMoTaWRe、CrCoFeV和CrMnReFe高熵合金薄膜。NbMoTaW系列高熵合金之氧化擴散行為，以及退火溫度對NbMoTaW系列高熵合金MOS元件特性變化的影響，也做了研究與討論。
NbMoTaW分別使用800˚C及1000˚C之氧化退火，當800˚C持溫30分鐘和120分鐘時，膜厚從原來700 nm分別增加到727 nm和782 nm，而1000˚C持溫則分別增加為785 nm與 832 nm。隨持溫時間上升，NbMoTaW的氧化逐漸趨緩，這與大部分高熵合金氧化擴散行為相同。高熵合金之緩慢擴散效應作用在整個溫度範圍下，並且在高溫下，嚴重晶格畸變效應影響降低。
由電容-電壓特性計算之NbMoTaW、Nb0.15Mo0.35Ta0.15W0.35和NbMoTaWRe有效功函數分別為4.65±0.13 eV、4.66±0.08 eV及4.56±0.04 eV，顯示高熵合金有功函數調變的可能性。而高熵合金閘極MOS元件較一般Ti/Al閘極MOS元件，有更好的抗氧化擴散能力，使其能在450˚C真空退火1小時後，仍有穩定之電容-電壓特性曲線，並且隨真空退火溫度達600˚C時，其漏電流相較於Ti/Al閘極MOS元件小許多，這表明高熵合金作為MOS元件閘極之潛力。但在MOS元件變溫量測實驗中發現，電容特性曲線有較嚴重變形，因此有關NbMoTaW系列高熵合金的高溫擴散行為需做進一步深入研究。

In our study, the properties of high-entropy alloy (HEA) materials apply to metal-oxide-semiconductor (MOS) capacitor is explored to study the oxidation diffusion behavior between the metal gate and the oxide layer. It expects that the excellent stability of high-entropy alloys can improve the current breakdown of power semiconductor devices.

The oxidation annealing experiment of NbMoTaW is performed at 800˚C and 1000˚C respectively. It shows that as the holding time increases, the oxidation of NbMoTaW gradually slows down, which indicates that the high-entropy alloy has excellent resistance to oxidation diffusion. And HEA/SiO2/p-type silicon substrate multilayers MOS capacitors are also made to measure the capacitance-voltage characteristics, calculating the work function of HEA and the equivalent oxide thickness change.

The HEA/SiO2/p-type silicon substrate multilayers MOS capacitors are prepared by sputtering. According to our results, the oxidation diffusion behavior of high-entropy alloys is dominated by sluggish diffusion effects, and it shows that the effects of severe lattice-distortion are reduced at high temperatures. The effective work functions of NbMoTaW, Nb0.15Mo0.35Ta0.15W0.35 and NbMoTaWRe extracts from capacitance-voltage characteristics are 4.65±0.13 eV, 4.66±0.08 eV and 4.56±0.04 eV, respectively, which shows that HEA has the possibility of work function modulation. Compared with ordinary Ti/Al gate MOS devices, high-entropy alloy gate MOS devices have better oxidation diffusion resistance and smaller leakage current, which shows the potential of HEA as MOS device gate. However, in the variable temperature measurement experiment of MOS device, it shows that the capacitance characteristic curve is shifted. Therefore, the high temperature diffusion behavior of the NbMoTaW series of HEA is needed to be further studied.

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