氧化物半導體薄膜電晶體接觸電阻之研究

Abstract

氧化物半導體近年來相當迅速地發展，因為其同時具有透明、可室溫成長、高載子遷移率等等有趣特性，使得氧化物半導體具有許多應用上的高度潛力，其中又以非晶態氧化銦鎵鋅具有高均勻度、低製程溫度與再現性佳等優勢，為目前最被看好應用在顯示器工業的氧化物半導體材料，甚至有機會取代現有的非晶矽薄膜電晶體。 電晶體元件中，源極、汲極的導體電極與主動層半導體接觸，是一個標準的金屬─半導體接面，常會形成能障，降低甚至破壞元件的應有的性能，因此定量出介面的接觸電阻並設法避免接觸能障是相當重要的。 在本論文中，定量研究了非晶態氧化銦鎵鋅與各種電極材料之間的接觸電阻。首先，以TLM測詴結構量測分析了非晶態氧化銦鎵鋅與鉬、鈦、銅以及氧化銦錫電極之間的特徵接觸電阻率，比較不同電極材料的差異並探討載子濃度造成的影響，並分別探討了接觸型態、熱退火處理以及電漿處理的效應。接著，使用並討論了結合TLM與CER的量測架構以及一維與二維CBKR測詴結構分析萃取特徵接觸電阻率的方法，同時討論各種測詴結構與量測方式應用於氧化物半導體薄膜電晶體的實用性。論文的最後，應用了前面對於接觸電阻的各種結果，實際製作出使用不同接觸電極技術的非晶態氧化銦鎵鋅薄膜電晶體元件。

Oxide semiconductors have gained much attention in recent years due to their interesting characteristics such transparency, room-temperature growth and high mobility. These benefits render their highly potential for many applications. Amorphous indium gallium zinc oxide (a-IGZO) has the highly potential for applications in thin-film transistor (TFT) industry among all oxide semiconductor materials, because of its high uniformity, low fabrication temperature and good reproducibility. For TFT devices, energy barriers will exist at the interfaces of conductor- semiconductor contact like source/drain regions. High contact resistance will degrade the performance of devices. Therefore, it is important to be able to measure contact resistance and to avoid the conditions of poor contact. In this thesis, we measured the contact resistance between a-IGZO and electrode materials, such as Mo, Ti, Cu and indium tin oxide (ITO). First, we measured the specific contact resistivity by the TLM test structure. We discuss the influences of electrode materials, carrier concentrations, contact type, annealing treatment and plasma treatment. Then, we compared varies structures and methods of extracting specific contact resistivity, such as combination of TLM and CER, one dimension CBKR, and two dimension CBKR. Finally, we use the previous results to fabricate a-IGZO TFTs with different contact technologies.