小線寬金屬氧化物薄膜電晶體及複合式光偵測器

Abstract

本論文之主軸為將微影舉離製程(lift-off lithography)與非晶銦鎵氧化鋅薄膜電晶體(a-IGZO TFT)以及複合式光偵測器(hybrid photodetector)兩種元件作結合。第一部份，考量高透明度的薄膜電晶體可廣泛的用於顯示科技領域，且溶液製程成本低廉兩項大優勢，我們嘗試以氧化鋁作為閘極絕緣層，並成功地在玻璃基板上製作出載子遷移率(mobility)為10.33 cm2/Vs的高透明度的非晶銦鎵氧化鋅薄膜電晶體。此外我們也成功使用溶膠凝膠法(sol-gel process)，製作出不同原子莫耳比例的非晶銦鎵氧化鋅薄膜電晶體。由於小線寬製程的開發能夠使實驗室各項相關研究成果更加符合業界需求，因此本研究引入微影舉離製程(lift-off lithography)，成功地縮短了上述兩種非晶銦鎵氧化鋅薄膜電晶體之通道長度，讓高透明度非晶銦鎵氧化鋅薄膜電晶體及藉由溶膠凝膠法(sol-gel process)所製作的非晶銦鎵氧化鋅薄膜電晶體在通道長度10um下維持良好的電性，載子遷移率分別為9.8cm2/Vs及 3.31cm2/Vs，而臨界電壓(Vth)分別為0.26V及0.73V。 第二部分，光偵測器能廣泛的用於我們生活中，為了降低成本、簡化製程及增進光偵測器的感測靈敏度，我們將微影舉離製程與有機光偵測器做搭配。第一步，我們先成功地以溶液製程(solution processed)方式在玻璃基板上製作出外部量子效率達60%的有機光偵測器(organic photodetector)。接著，我們引入ZnO緩衝層覆蓋於有機層上方以減少微影製程對下方有機層之傷害，製作出外部量子效率30%的有機/無機複合式光偵測器。同時，我們也證實了微影舉離製程在複合式光偵測器上的可行性。

This dissertation aims to develop lithography lift-off process, and combine it with amorphous indium gallium zinc oxide semiconductor thin-film transistor (a-IGZO TFT) and organic photo detector (OPD). In the first part, Owing to the widely used of High transparency thin film transistor (TFT) in display technology and the advantage of low-cost in solution process, we are interest in fabricating high transparency a-IGZO TFT and sol-gel a-IGZO TFT. A high transparency a-IGZO TFT with the mobility of 10.33 cm2/Vs is fabricated on glass substrate by using Al2O3 as gate dielectric. Likewise, sol-gel a-IGZO TFTs with different atomic molar ratio is produced by solution process. Besides, to make our research applies to the requirements of the industry, the developing of lithography lift-off process is necessary. By utilizing the lift-off process, the channel length of high transparency a-IGZO TFT and sol-gel a-IGZO TFT can be shorten to 10um. In the second part, considering that photodetectors has been widely used in our life, we urge to develop and simplify the fabrication process as well as promote the resolution of photodetector, and the lithography lift-off process is induced. OPD (organic photodetector) with the EQE(External Quantum Efficiency) of 60% is fabricated successfully by solution process. Usually, the removal of photoresist in lithography process will damage the underlying organic semiconducting layer seriously. Hence, we propose a “hybrid” structure for achieving a small line width OPD by lithography process through inserting a ZnO buffer layer into conventional OPD. Hybrid OPD with the EQE(External Quantum Efficiency) of 30% is fabricated. With ZnO buffer layer on top of organic layers, metal electrode with resolution down to 10 um can be patterned on top of the hybrid film successfully.