面板型高遷移率微晶矽薄膜電晶體

Abstract

在資訊發達的現代，平面顯示器的需求越來越大，除了本來就有廣大市場的液晶顯示器外，舉凡日漸普及的智慧型手機、相機、以及筆記型電腦等等，使得軟性電子元件產業快速的崛起。軟性電子元件具備許多優點，輕量化、可饒式、耐用、可以因應更多自由的設計。目前最成熟也最常使用在液晶面板或是軟性電子元件材料為氫化非晶矽，氫化非晶矽擁有成本低、容易大面積生產等特性，因此被廣泛的應用。但是氫化非晶矽擁有許多缺點，其驅動電壓較高，載子遷移率較低，會有劣化等情形，因此，近來研究發展朝向微晶矽的材料，其材料中缺陷較少，場效載子移動率較非晶矽高，也可於低溫下成長，是具有取代氫化非晶矽成為新一代軟性電子及大面積面板中元件材料潛力。 本篇論文中，利用感應耦合電漿化學氣相沉積系統及熱燈絲化學氣相沉積系統在低溫200℃下沉積出高結晶性的氫化微晶矽薄膜以及低電阻率的n型氫化微晶矽薄膜，並且藉由XRD及SEM確認氫化微晶矽薄膜，使用共平面型以及堆疊型兩種不同結構，成功的製作出不需離子佈植、低成本、低溫、高結晶性的薄膜電晶體，開與關的電流差距超過106、開關速度達到S=0.34 V/decade，並且電子遷移率達到90 cm2/V-s以上，展現出極高的潛力。

The demands of flat panel displays have been increased in our modern which is full of information. The growing popularity of smartphones, cameras and notebooks proper the industry of flexible electronic devices rapidly. Flexible electronics possess several advantages, such as lightweight, flexibility, reliability and designed facility. Currently, a-Si:H TFTs have been widely used in AMLCD and are compatible with flexible substrate because of it’s low temperature process. However, low device mobility, higher driving voltage and electrical instability are the main disadvantages of a-Si :H TFTs. Therefore, micro-crystalline(μc-Si:H) or nano-crystalline silicon(nc-Si:H) become a very promising alternative for flexible displays and large area electronic applications. The charge carrier mobility exceeds the mobility of a-Si:H significantly and is also compatible with flexible substrate. In this thesis, high quality and low resistivity of intrinsic and n-type μc-Si:H films were developed at low temperature of 200oC by Inductively-coupled plasma chemical vapor deposition system(ICPCVD)、Hot-Wire chemical vapor deposition system (HWCVD) and very-high frequency CVD (VHF-CVD).The μc-Si:H films was analyzed by XRD to investigate the film crystallinity and SEM to demonstrate the grain size. Two structures, coplanar and staggered TFT, were demonstrated. Finally, we successfully fabricate μc-Si:H TFTs without source/drain implantation and with high electron mobility exceeding 90 cm2/V-s, low subthreshold swing of 0.34-0.38 V/decade and high current ON/OFF ratios of more than 106, Which is highly potential for flexible electronic applications.