二硒化鎢薄膜電晶體之製程與分析

Abstract

在2004年石墨烯被成功製備之後，證實了此假設性的單原子層二維結構的確能夠單獨存在，此一成就為兩位物理學家Andre Geim 與 Konstantin Novoselov帶來了莫大的榮耀 - 2010年的諾貝爾獎，也引起了眾多科學家對二維材料的興趣，而過渡金屬硫屬化物也在此嶄露頭角，在這股潮流之中再度被科學家們重視，從不同角度出發研究，在奈米級電子與光電元件中極具發展潛力。 若要運用在集成電路上，大面積且高品質的薄膜製備能力是必須的趨勢，因此我們與中央研究院原子與分子科學研究所的李連忠博士研究室合作，由李博士研究室的研究人員們以化學氣相沉積(CVD)方式製備出大面積且高品質的單分子層二硒化鎢(WSe2)薄膜，再由我們運用國立交通大學奈米中心與國研院奈米元件實驗室的資源進行Top-Gate的薄膜電晶體元件製作。 在本論文中，我們確立了二硒化鎢薄膜電晶體的製作流程，針對不同種類氧化層沉積造成的影響做了大量的量測與統計分析，以及各種電性參數的萃取；在氧化層沉積的部分我們已有了初步的結果，目前最佳特性的元件是以150℃低溫ALD沉積的二氧化鉿，而以二氧化矽/高介電常數氧化層的雙氧化層能有效改善閘極漏電問題，但特性有所限制。儘管還有很多尚未找到解決之道的問題，但是本論文中的一系列實驗已經承先啟後地為未來更深入的研究奠定了基礎。

In 2004, the renowned 2D material, graphene, was successfully produced by Andre Geim and Konstantin Novoselov, the laureates of 2010 Nobel Prize in Physic. This amazing achievement has proved that the 2-D structured monolayer is not only a scientific hypothesis but a truly existing material system. It also inspired the explosive research on graphene and other 2-D materials, for example, Transition-Metal- Dichalcogenides (TMD). From bulk to few layers, TMD has shown promising potentials in electronic and optical devices. When it comes to Integrated Circuits (IC), large-area and high-quality TMD thin films are required. Therefore, we have coworked with the group led by Dr. Lance Li, Institute of Atomic and Molecular Sciences, Academia Sinica. The WSe2 film is produced using a CVD method at Academia Sinica. Then we produce top-gate WSe2 Thin Film Transistor (TFT) in Nano Facility Center, National Chiao Tung University and National Nano Device Laboratories. We have already constructed the basic process flow of making top-gate WSe2 TFT with reasonable characteristics. In this thesis, I will show our experiment results, including statistics of device parameters. We focus particularly on the different gate oxide deposition methods and their impacts on the device performance. The 150℃ low-temperature ALD deposited HfO2 is the best in our devices, and the SiO2/high-k dielectric bilayer oxide also improve yield but limited device performance. Although there are still many problems to be solved before realizing high-performance devices, the current study serves as a good starting point for future research on WSe2 TFT.