高介電係數介電質於五苯有機薄膜電晶體及金氧半場效電晶體之研究

Abstract

由於以五苯(pentacene)為主動層之有機薄膜電晶體可廣泛的應用於無線射頻身分識別標籤、邏輯電路、顯示器驅動元件、感測元件，因此五苯有機薄膜電晶體成為世界上各研發單位的重要研究課題之ㄧ，且在元件性能上屢有重大的突破與進展。在本研究論文中，我們將探討高介電系數介電層在有機薄膜電晶體的應用，並研究分析高介電系數介電層對於元件特性的改善。 首先我們製作與整合高介電系數氧化鉿鑭(HfLaO)介電層與氮化鉭(TaN)金屬閘極於五苯有機薄膜電晶體，此元件量測到低的操作電壓、小的次臨界擺幅、低的臨限電壓、良好的場效遷移率。此良好的元件特性可以說明氧化鉿鑭介電層適合應用於有機薄膜電晶體。 為了達到未來可撓式電子的需求，我們降低製程溫度在可撓的聚亞醯胺基板上製作氧化鉿鑭/五苯有機薄膜電晶體。此元件也展現良好的元件特性，在低的2.5伏操作電壓下，量測到0.13 V/decade的次臨界擺幅、-1.24伏的臨限電壓、0.13 cm2/V•s的場效遷移率。 根據製作高介電系數氧化鉿鑭為介電層之五苯有機薄膜電晶體所得到的良好電性，我們進一步發展使用高介電系數氮氧化鉿(HfON)為電荷捕捉層，在可撓的聚亞醯胺基板上製作非揮發性五苯有機薄膜電晶體記憶體元件。利用高介電系數介電材料氮氧化鉿為電荷捕捉層、氧化鉿鑭為電荷阻擋層和二氧化鉿(HfO2)為電荷穿隧層，五苯有機薄膜電晶體記憶體元件可以得到低的寫入與抹除電壓。 最後我們探討在氮氧化矽(SiON)上，以高介電系數氧化鉿鋁(HfAlO)介電層為覆蓋層去調變臨界電壓，使其適用於p型金氧半場效電晶體，我們也分析調變臨界電壓的物理機制。在最佳1.5奈米厚的氮氧化矽，氮化鉬(MoN)/氧化鉿鋁/氮氧化矽p型金氧半場效電晶體可得到0.85奈米的等效氧化層厚度、低的臨界電壓、良好的次臨界擺幅、高的場效遷移率。平帶電壓朝正電壓方向改變被證明是由於氧化鋁(Al2O3)與氮氧化矽的交互擴散與反應，形成氧化矽鋁(AlSiO)矽化物並造成帶電的氧空缺。

Due to the widespread applications such as radio frequency identification tags, logic circuits, display driver and sensors, the pentacene-based organic thin film transistors (OTFTs) are widely investigated and have many remarkable breakthroughs in performance. In this dissertation, we investigate the application of high dielectric constant (κ) dielectric to improve the performance and function of OTFTs. First of all, we demonstrate the integration of HfLaO high-κ dielectric and TaN metal gate into pentacene OTFTs to get low operation voltage, small sub-threshold swing (SS), low threshold voltage (VT) and good field effect mobility (μ). Theses results indicate HfLaO is a good dielectric for OTFTs. In order to meet the requirements of future flexible electronics, we decrease the process temperature to develop HfLaO/pentacene OTFT on flexible polyimide substrates. This device also shows good device integrity of a small SS of 0.13 V/decade and a VT of −1.25 V and a good μ of 0.13 cm2/V•s at a low operating voltage of 2.5 V. Based on the good electrical characteristics of pentacene OTFT incorporated with high-κ HfLaO dielectrics, we further use high-κ HfON as a charge trapping layer to develop organic pentacene non-volatile OTFT memory fabricated on flexible polyimide substrate. By using high-κ HfON□ □as a charge trapping layer, HfLaO as a blocking layers and HfO2 as a tunneling layer, the pentacene OTFT memory shows record low program/erase voltage. Finally, we study the High-κ HfAlO as a capping layer on SiON to modulate VT for p-MOSFET application. The mechanisms of VT modulation also have been investigated. Under the optimized 1.5 nm SiON, good device integrity of small 0.85 nm equivalent-oxide-thickness, low Vt, good SS and high mobility are obtained in the MoN/HfAlO/SiON p-MOSFETs. The large positive flatband voltage shift is explained due to the forming charged oxygen vacancies in AlSiO silicate, which is originated from diffusion and interaction of Al2O3 and SiON.