本研究旨在探討將高熵合金材料應用於金屬-氧化物-半導體電容器金屬閘極層之特性研究及將高熵合金薄膜應用在擴散阻障層的可行性。利用電性與材料分析的方法研究金屬與氧化層介面的熱穩定性。研究的材料包括Nb25Mo25Ta25W25、Nb15Mo15Ta35W35、Nb15Mo35Ta15W35高熵合金薄膜，以及高溫退火對NbMoTaW高熵合金MOS元件特性的影響。
由電容-電壓特性曲線計算出Nb25Mo25Ta25W25、Nb15Mo15Ta35W35、Nb15Mo35Ta15W35有效功函數分別為4.63±0.03 eV、4.78±0.04 eV及4.67±0.11 eV，顯示高熵合金功函數調變的可能性。而高熵合金閘極MOS元件較Ti/Al閘極MOS元件，有更好的熱穩定性。能在500˚C真空退火後，仍有穩定之電容值，漏電流相較於500˚C真空退火後的Ti/Al閘極MOS元件小了50~100倍。退火後的NbMoTaW高熵合金MOS元件功函數可維持與未退火前接近的值，這表明高熵合金作為MOS元件閘極之潛力。
Ti/Al閘極MOS元件的熱穩定性不佳，使用Nb25Mo25Ta25W25將Al取代，形成Ti/Nb25Mo25Ta25W25 閘極MOS元件。Ti/Nb25Mo25Ta25W25 MOS元件熱穩定變好，在經過500˚C真空退火後，電容值變得穩定，漏電流小了50~100倍，功函數則是能維持在定值。熱穩定性較Ti/Al閘極MOS元件好，這表明將Nb25Mo25Ta25W25取代熱穩定不佳的Al可以有效改善熱穩定性。
NbMoTaW皆是由耐火金屬所組成，而熱穩定性較佳的金屬，其擴散阻障能力也會很好。因此將其應用在擴散阻障層，Si/NbMoTaW/Cu樣品在500˚C真空退火後，在樣品表面只檢測到銅元素，表示尚未發生銅矽相互擴散的行為。在700˚C真空退火後，則在表面檢測到許多Nb、Mo、Ta及W的矽化物，代表NbMoTaW薄膜作為擴散阻障層能在500˚C時，有效的阻障銅的擴散。

The purpose of this research is to explore the characteristics of applying high-entropy alloy materials to the metal gate of metal-oxide-semiconductor capacitors and the feasibility of applying high-entropy alloy films to the diffusion barrier layer. Use electrical and material analysis methods to study the thermal stability of the interface between the metal gate and the oxide layer. The material studied include Nb25Mo25Ta25W25, Nb15Mo15Ta35W35, and Nb15Mo35Ta15W35 high-entropy alloys,and the effect of high-temperature annealing on the characteristics of NbMoTaW high-entropy alloy MOS devices
The effective work functions of Nb25Mo25Ta25W25,Nb15Mo15Ta35W35 and Nb15Mo35Ta15W35 calculated from the Capacitance-Voltage(C-V) characteristic curves are 4.63±0.03 eV, 4.78±0.04 eV and 4.67±0.11 eV, respectively, showing the possibility of high-entropy alloy work function modulation. The high-entropy alloy gate MOS device has better thermal stability than Ti/Al metal gate MOS device. After vacuum annealing at 500˚C, there is still a stable Capacitance-Voltage(C-V) characteristic curve, and the leakage current is 50-100 times smaller than that of Ti/Al gate MOS devices after vacuum annealing at 500˚C. The work function of the annealed NbMoTaW high-entropy alloy MOS device can maintain a value close to that before the annealing, which indicates the potential of the high-entropy alloy as a gate for MOS devices.
The thermal stability of Ti/Al metal gate MOS components is not good. Use Nb25Mo25Ta25W25 to replace Al to form Ti/ Nb25Mo25Ta25W25 metal gate MOS. The thermal stability of Ti/Nb25Mo25Ta25W25 MOS becomes better. After 500˚C vacuum annealing, the Capacitance-Voltage(C-V) characteristic curve becomes stable, the leakage current is also 50~100 times smaller than the Ti/Al MOS, the work function can be maintained at a constant value.The thermal stability is better than that of the Ti/Al MOS device, which shows that the Nb25Mo25Ta25W25 replacing Al can effectively improve thermal stability.
NbMoTaW is composed of refractory metals, and thermally stable metals have good diffusion barrier capabilities. Therefore, it can be used in the diffusion barrier layer..Si/NbMoTaW/Cu sample after annealing at 500°C, only copper will be detected on the surface of the sample,which means that there is no mutual diffusion of copper and silicon. After annealing at 700°C, non-copper substanceis detected on the surface, which means that the NbMoTaW thin film diffusion barrier layer can effectively block the diffusion of copper at 500°C.

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