化學氣相沉積鑽石之新技術研究

Abstract

本計畫主要探討新的化學氣相沉積技術，用以增加鑽石薄膜沉積的品質。計畫分三 年執行，目標分為兩大部分:一是利用金剛烷增加成核密度於表面平整之矽基板上，另一 則是利用金屬改進同質磊晶鑽石成長的品質與厚度。 金剛烷(C10H16)的碳原子互相之間是sp3 鍵結，最外圍則是氫原子包覆所有碳原子， 可視為具有最小鑽石單位的分子，亦可做為薄膜形成所需之核種。室溫下，金剛烷為固 態，但具有高揮發性，且價格不貴。因此，本計畫擬開發適當的溶液溶解金剛烷，然後 以浸潤塗佈(dip coating)方式，使金剛烷附著於矽晶片上，做為晶種，再置入微波電漿中 沉積出鑽石。另外，將以金剛烷氣體為碳源，導入微波電漿中沉積鑽石於基板之上，並 研究成核與成長的可行性。計劃從電漿光譜與材料分析之結果，研究各種不同的製程條 件下金剛烷可能發生的變化以及對鑽石沉蹟之影響，主要關鍵著重在成核階段，因此高 解析之電子顯微鏡將是重要的觀察與分析技術。 同質磊晶鑽石成長之研究，則是在(111)單晶鑽石上，鍍上20-100 nm 之金，微波電 漿化學氣相沉積仍可以同質磊晶方式成長，並有助於磊晶薄膜的成長。本計畫擬使用 金、銅、鎳等不形成碳化物之金屬，將其鍍於單晶鑽石之上，並加以熱處理，然後觀察 與分析這些金屬對微波電漿化學氣相沉積鑽石的影響。金屬熱處理的主要目的，期望使 其成為島狀顆粒，具有各種不同尺寸與密度，對磊晶鑽石膜的應力、缺陷、厚度可能有 不同程度的影響。除此之外，將利用電子顯微鏡、高解析X 光繞射及拉曼光譜等分析技 術分析鑽石薄膜與金屬之特徵。最後綜合三種不同金屬的效應，研究鑽石磊晶成長的過 程與形成連續膜的合併機制。

Newly developed techniques for diamond growth by chemical vapor deposition (CVD) will be explored to improve the film quality. This proposal for three years study includes two major topics. One is to apply adamantane for enhanced diamond nucleation on smooth substrate. The other one is to use metal coating for improvement on the quality of homoepitaxial diamond with increasing film thickness. Adamantane (C10H16) as solid at room temperature has carbon atoms in sp3 bonding with each other and all hydrogen atoms on the outer shell surround carbon atoms. Therefore, it can be considered as the smallest unit of diamond which could be used as nucleus for film growth. Adamantane is easily evaporated and commercially available with reasonable cost. Appropriate solution of adamantane will be developed in this study for dip coating of adamantane on substrate to enhanced diamond nucleation in CVD. Alternatively, adamantane as carbon gas source will be introduced into microwave plasma as nuclei in gas phase for diamond deposition. Optical emission spectroscopy measured from plasma and material analytical techniques will be used to study the possible change of adamantane and its effect on deposition under various CVD conditions. As diamond nucleation plays a critical role in diamond formation, high resolution electron microscopy observations will be essential. It is feasible to have homoepitaxial growth of diamond in microwave plasma CVD if a coating of gold in 20-100 nm is applied to on (111) single crystal diamond. In this study, gold, copper, and nickel which are not carbide forming elements will be coated on single crystal diamond substrates, and heat treatment of coated metals will be applied to change their sizes and densities. The effects of such treated metals on CVD diamond homoepitaxy will be examined in terms of stress and defects in diamond film with thickness using characterization techniques of electron microscopy, high-resolution x-ray diffraction, and Raman spectroscopy. In addition, evaluation of the effects of all these three metal coating will be carried out to study the evolution of film growth and the mechanism for formation of continuous film in coalescence.