不同氧氣流量對非晶系銦鎵鋅氧薄膜電晶體製程之影響

Abstract

近年來，有許多關於非晶系氧化半導體(AOS)的研究著作產出，銦鎵鋅氧(IGZO)是AOS的其中一種，其物理特性相當適合於作為薄膜電晶體(TFT)的主動層，相對於非晶矽(a-Si)或多晶矽(p-Si)，銦鎵鋅氧具有許多優點如高載子漂移率、低製程溫度和屬於透明材質等；但是AOS本身也具有一些缺點，其對於環境中的氧氣、水氣、光源照射以及製程參數等都相當的敏感，根據過去關於AOS的文獻指出，以上的敏感要素皆能夠改變氧空缺的濃度使得製程的元件電性產生改變。本論文的實驗可分成兩個部分，分別為探討製程氣體Ar/O2比例對於元件的影響以及嘗試將元件製作於可撓式不鏽鋼基板上，利用XPS能譜的分析取得不同Ar/O2比例下金屬原子比例(銦、鎵、鋅)和氧空缺濃度的變化情形，我們推斷在不同製程氣體Ar/O2比例下因金屬原子的變化才導致氧空缺濃度改變間接使得臨限電壓(threshold voltage, Vth)產生偏移；另外在不鏽鋼基板製程方面，我們雖然將元件製作於基板上並且可在平面與彎曲情況下成功量測，但經過所有彎曲量測程序後元件便毀壞，所以減少元件所受的應力破壞將是未來研究的目標之一。

Recently, there are many researches about amorphous oxide semiconductors (AOSs). IGZO is one kind of AOSs and possesses physical characterictics that are suitable for TTFTs. Relative to a-Si or p-Si, IGZO have lots of advantages of high mobility, low fabrication temperature, viewing light transparency and so on. However, they are sensitive to oxygen, moisture, light illumination and fabrication parameters. According to many researches about IGZO, the key issue about unstable properties was caused by the variation of oxygen vacancy concentration. In this thesis, we made a study of the effects of Ar/O2 ratio in a-IGZO deposit processes and attempted to fabricate device on flexible stainless steel foils. The metal atomic ratios (In, Ga and Zn) and oxygen vacancy concentrations in different Ar/O2 ratio were presented by XPS spectra analysis. We inferred that the variations of oxygen vacancy concentration were caused by the varied metal atomic ratios and resulted threshold voltages shift indirectly. In devices on the SSFs, the TFT characteristics were obtained successfully in planar and bend state but failed after all bending measurement processes. The improvement stresses on devices is one of the future plans.