| 摘要: | 鑽石擁有許多優異的物理、化學、光學、力學與電學特性，例如它擁有最高的熱傳導係數、具化學惰性、具有最高硬度、高楊氏係數與低摩擦係數、具有寬能隙與寬的光學穿透頻域。因此，鑽石膜可以用來解決目前許多工程上難解的問題。雖然鑽石擁有這些極佳的性質，但是天然鑽石高成本與產量的限制，使得工業應用大為受限。然而，現今使用化學氣相沉積(chemical vapor deposition, CVD)法來成長鑽石膜，已經是相當成熟且普遍的方法。然而，由於鑽石晶體成長時，晶粒間柱狀成長競爭之特性使然，所以當鑽石膜厚度愈厚、晶粒愈大時，所得到的表面粗糙度也愈高。根據所沉積的厚度與成長參數之不同，表面粗糙度值(Ra)可以從數十μm到數μm。然而，低表面粗糙度與平滑的表面幾乎是許多工業應用的基本需求。目前有許多研究者以各種方法試圖降低多晶鑽石膜的表面粗糙度，像是以機械拋光、化學拋光、熱化學拋光、化學輔助機械拋光、雷射拋光、離子束拋光、電子迴旋共振電漿拋光與反應離子蝕刻等方式。在這些方法當中並沒有一種可以達到快速且有效的拋光。
在本論文中，CVD多晶鑽石膜將分別以常用的熱化學拋光、雷射拋光、感應耦合電漿蝕刻、熱氧化蝕刻與反應離子蝕刻等方式來進行實驗，除探討拋光或蝕刻機制對表面粗糙度的影響外，並分別以掃描式電子顯微鏡與微拉曼頻譜分析儀來觀察其表面形貌的改變與微結構成分分析。透過一系列的實驗，提出最有效率的快速複合拋光鑽石膜的加工方法。
Diamond has many outstanding physical, chemical, optical, mechanical, and electrical properties such as the highest thermal conductivity, the extreme chemical inertness, the highest known hardness, the lowest compressibility of known material, high in Young’s modulus, low in friction coefficient, wide in band gap, and a wide optical transparency bandwidth. Thus, diamond can be a potential solution to many advanced engineering problems. Though diamond possesses all those excellent properties, high cost and difficulty in machining have hindered its industrial applications. Nowadays, using CVD method to synthesize high quality diamond film is a rather mature and stable technology. Diamond grains normally get bigger and the surface gets rougher when the film gets thicker as the result of competition growth. Depending on the film thickness and growing conditions, the surface roughness can vary from tens micrometer to a few micrometers. However, a smooth surface in many industrial applications is a necessity. Many researches have been conducted to improve the surface roughness of CVD diamond film by various approaches such as by mechanical polishing, chemical polishing, thermo-chemical polishing, chemical- assisted mechanical polishing, laser ablation, ion beam irradiation, ECR plasma polishing, and reactive ion etching. Unfortunately, none of them could quickly and efficiently lower the surface roughness, especially in terms of large area and thick CVD diamond film.
In this thesis, the CVD diamond film was conducted with the thermo-chemical polishing, laser ablation, inducted coupling plasma, and reactive ion etching, respectively. The research aimed to improve the surface roughness and to investigate the mechanism of material removal. The SEM micrographs and micro-Raman were used to analyze the morphology and microstructure of the obtained surface. The results showed that the compound polish method could effectively shorten the processing time needed to polish the CVD diamond by weakening its surface structure. |
