使用微波退火處理大氣常壓電漿輔助化學氣相沉積製備非晶銦鎵鋅氧薄膜電晶體之研究

Abstract

傳統薄膜電晶體普遍具有較大的操作電壓、次臨界擺幅、臨界電壓與製程溫 度，也伴隨著低電子遷移率等等，明顯地，傳統薄膜電晶體已無法滿足現今顯示 器技術所需的高解析度、高電子遷移率或者低溫製程等需求。然而高解析度、高 幀率與大尺寸的螢幕是未來3D 顯示器中的趨勢，而非晶銦鎵鋅氧薄膜是非常有 潛力的材料，來達成高遷移率和良好均勻度的薄膜電晶體，相較於傳統非晶矽薄 膜電晶體（a-Si:H TFTs）有較大的電子遷移率(>10 cm2/V·S)、高穿透率及低製程 溫度，然而製程均勻度與製程步驟亦比低溫多晶矽薄膜電晶體(LTPS)來得均勻與 簡單。 本篇論文，使用了大氣壓電漿輔助化學氣相沉積(AP-PECVD)來製作銦鎵鋅 氧主動層，配合微波退火處理來提升非晶銦鎵鋅氧薄膜電晶體的特性。藉由大氣 電漿系統即可不用真空系統，便可沉積銦鎵鋅氧通道層，因此可降低維護真空系 統之成本，且配合大氣電漿之噴塗技術有利於大面積製造；此外，微波退火為快 IV 速且直接性的退火方式，使製程具有較低的熱預算、較短的時間，以滿足低溫製 程的需求。 我們成功製作出藉由大氣壓電漿輔助化學氣相沉積之銦鎵鋅氧主動層，且 經微波退火處理，在微波退火1200 瓦100 秒過的銦鎵鋅氧主動層之薄膜電晶體 效能有顯著地提升，其擁有最大的電子遷移率7.66cm2/V·s，最小的次臨界擺幅 200mV/decade；在600 瓦100 秒的微波退火下，有高的開關電流比 1.37×107 且 小的關閉電流 1.3×10-13 安培，明顯地，微波退火處理於大氣壓電漿輔助化學氣 相沉積之銦鎵鋅氧薄膜電晶體，有顯著地改善。

The conventional thin film transistors commonly are high operation voltage, high threshold voltage, poor subthreshold swing, high processes temperature, and lower field-effect mobility. Obviously, the conventional thin film transistors are not satisfied with the technology of display with high resolution, high field-effect mobility and low processes temperature etc. nowadays. However, high resolution, high frame rate and large size display are the trend of 3D display in the future and amorphous indium gallium zinc oxide (a-IGZO) has a great potentialities amount numerous materials to be thin film transistors (TFTs) with high field-effect mobility and good uniformity which possess high carriers mobility, high transparency and low processes temperature compared with amorphous silicon thin film transistors (a-Si:H TFTs). Furthermore, the process steps of a-IGZO TFTs are more simple than low temperature poly crystalline silicon thin film transistors (LTPS TFTs) and the uniformity of a-IGZO TFTs are better than LTPS TFTs. VI In this investigation, a-IGZO channel layer is fabricated by atmospheric-pressure PECVD (AP-PECVD) in atmosphere without vacuum system so that we could not only save a lot of cost to maintain it also apply to large area manufacturing and then it is treated by microwave annealing (MWA) to boost the performance of a-IGZO TFT. Moreover, MWA is not only a directly thermal convention but also a rapid thermal process so it could be claimed low thermal budget and rapid process to be compatible with low temperature process. Finally, we successfully fabricated a-IGZO TFT by AP-PECVD to deposit IGZO channel and annealing active layer by microwave. It reveals that lower off current improvement and better on/off current ratio are obtained from the case with 600W of microwave power for 100s and it has low off current of 1.3×10-13 A and better Ion/Ioff of 1.37×107. It exhibited highest mobility of 7.66cm2/V·s and smallest subthreshold swing of 200mV/decade under MWA 2P 100s. Obviously, amorphous InGaZnO thin film transistors fabricated by AP-PECVD have significantly improvement by microwave annealing treatment.