感應式耦合電漿輔助化學氣相沉積法低溫生長石墨烯於金屬薄膜

Abstract

本論文主要是探討利用感應式電漿輔助化學氣相沉積法(ICP-PECVD)來優化石墨烯製程，是一種新式製程方法，其特點為可以直接將石墨烯沉積於金屬表面，且可於低溫環境下短時間成長石墨烯，相較於傳統化學氣相沉積法有更進一步的突破。 一開始先以金屬銅作為測試金屬，於銅箔上進行生長，之後將技術轉移至金屬薄膜上，接著調控石墨烯成長參數，以達到較佳的品質，並藉由掃描式電子顯微鏡觀測其生長形貌，最後量測其片電阻值進行分析，最終石墨烯的2D/G比例可達到0.39，片電阻值約1K歐姆。 之後將調整好之碳源流量參數應用於各試金屬薄膜上，並改變其生長時間以生長高品質石墨烯，如鈷、釕、鉬、鎢，各式金屬皆能生成出品質不錯的石墨烯，對於未來尺寸微縮後可能以其他金屬材料替代銅時，此成長方式依舊可以與製程匹配。之後我們將製程改良，透過提升初始石墨烯的生長溫度，突破了過往以電漿系統中多為垂直生長的石墨烯形貌，於鈷薄膜上成功生成出平坦無垂直狀的高品質石墨烯，於350 oC時2D/G可達0.4，若將射頻電源升高後於400 oC其2D/G之值可達0.6。 最後我們將石墨烯應用於金屬導線上，量測其崩潰電流。對於銅導線而言，覆蓋石墨烯的導線相較於未覆蓋石墨烯的銅導線，其可承載的電流提升了1.265倍，而在導線崩潰後石墨烯能承載電流為其提高可靠性；以鈷導線而言，覆蓋石墨烯的導線相較於未覆蓋石墨烯的電流值提升了1.67倍。

An innovative graphene growth method, inductively-coupled plasma chemical vapor deposition (ICP-PECVD), will be introduced in this article. Compared with the traditional chemical vapor deposition (CVD) method, graphene is able to be deposited on metal directly under ultra-low temperature and within short growth time in the new one, and this is definitely a breakthrough of graphene growth. In the beginning, Cu foil had acted as the experimental substrate to develop the process of this method, before the technique was utilized on Cu film. In this experiment, tuning parameters plays an influential role on growing excellent graphene. Therefore, the most proper parameters will be reported in this article. To ensure the quality of graphene, the layers, morphology, and electrical traits was measured by various instruments including Raman spectrum, scanning electron microscopy (SEM) and four-point probes method. In the end, the 2D/G ratio in Raman spectrum and sheet resistance turned out to be 0.39 and 1000 Ohm respectively. In the second part, the well-tuned precursor flow rate was utilized on a variety of metal films, and the growth time was tuned to receive high quality graphene. It is noticeable that optimal graphene was able to be grown on various metal films such as Co, Ru, Mo, and W. This consequence illustrated that this method was expected to stay valuable, although new metals will replace Cu in the advanced technique which has smaller nanowire size in the future. And afterwards a new approach was introduced. Raising the initial growth temperature in this process is able to overcome the challenge of the vertical structure in graphene grown by plasma. A totally horizontally structural graphene was successfully grown on Co by this enhanced method. The 2D/G ratio of this graphene become 0.4 at 350oC and 0.6 at 400oC. In the last part, the graphene can be applied and covered on Cu and Co nanowires to improve the breakdown current. Furthermore, the graphene layer can still carry current when the Cu nanowires breakdown. Take Cu nanowires for instance, the breakdown current of Cu nanowires with graphene increased to 1.265 times as high as that of the nanowires without graphene. As for Co nanowires, the breakdown current of the wires with graphene dramatically increased to 1.67 times higher as that of the one without graphene.