藉由大氣壓電漿輔助化學氣相沉積系統將氫導入非晶銦鎵鋅氧主動層之薄膜電晶體之研究

Abstract

近幾年來，由於相對傳統非晶矽薄膜電晶體，非晶銦鎵鋅氧薄膜電晶體有較佳的電子遷移率(>10 cm2/V•S)，較大的開關電流比(>106)，較小的次臨界擺幅，且不需像低溫多晶矽薄膜電晶體(LTPS)得經過再結晶，活化摻雜等高溫的製程步驟，因此在近幾年得到了相當大的注目。而低製程溫度及高穿透率使得非晶銦鎵鋅氧薄膜電晶體可以用來製造透明且具可撓性的顯示器。 在這次的研究論文裡，我們採用了大氣壓電漿輔助化學氣相沉積(AP-PECVD)來沉積我們的銦鎵鋅氧主動層。藉由大氣壓電漿輔助化學氣相沉積的幫助，我們可以不需要真空腔體或真空系統便可以沉積我們的銦鎵鋅氧主動層，因此可以降低我們的成本，提高產率，並且利用在大面積的製造上。 藉由在沉積時混入氫氣當沉積氣體，我們成功的改善了利用大氣壓電漿輔助化學氣相沉積製作出的非晶銦鎵鋅氧薄膜電晶體，沉積時以氮氣當沉積氣體的薄膜電晶體的電子遷移率有3.36 cm2/(V•S)，臨界電壓 2.36 伏特，次臨界擺幅 131 mV/decade，開關電流比 2.67×106。而沉積時加入氫的非晶銦鎵鋅氧薄膜電晶體表現出更佳的電性，它擁有更高的電子遷移率18.9 cm2/V•S，臨界電壓 1.9伏特，更小的次臨界擺幅 112 mV/decade，更高的開關電流比 2.54×107。

Recently, compared with the conventional a-Si TFTs, amorphous In-Ga-Zn-O (IGZO) thin film transistors have attracted attention that due to its better field-effect mobility (>10 cm2/V．S), larger Ion/Ioff ratio (>106), smaller subthreshold swing (SS) and better stability against electrical stress. Besides, compare with low temperature ploy-Si (LTPS) TFTs, the a-IGZO TFT do not need high temperature process to recrystallize and activate the dopant. Furthermore, the a-IGZO TFTs have low process temperature, high transmittance that can be applied to fabricate the full transparent TFT on flexible substrate. In this investigation, we used atmospheric-pressure PECVD (AP-PECVD) to deposit our IGZO active layer. With AP-PECVD, we could deposit IGZO thin film without vacuum system, thus, it could lower our cost, improved the throughput, and applied to large area manufacturing. We improved the a-IGZO TFT with AP-PECVD by adding the hydrogen while the deposition successfully. The electrical characteristics of a- IGZO TFT with active layer deposited with N2 as follow: the mobility was 3.36 cm2/V•S, the VT was 2.36 V, the subthreshold swing was 131 mV/decade, and the Ion/Ioff was 2.67×106. The TFT of a-IGZO active layer deposited with Ar+H2 gas exhibits higher mobility of 18.9 cm2/V•S, VT of 1.9 V, lower subthreshold swing of 112 mV/decade, higher Ion/Ioff of 2.54×107.