利用過濾式陰極電弧蒸鍍法製備奈米多層硬膜之研究

Abstract

電子封裝製程的微縮化與高頻化使封裝基板從傳統的FR4發展至BT樹脂基板、氧化鋁（Al2O3）、氮化鋁（AlN）等特用基板，由於元件特性及環保需求，電路板加工製程須以乾式切削完成之，故精密機械加工的需求也日趨嚴苛，傳統碳化物及氮化物燒結工具已不敷使用。奈米多層薄膜比單層薄膜具有更佳的硬度與高溫抗氧化性，本論文利用過濾式陰極電弧蒸鍍技術製備奈米多層薄膜以供電路板鑽頭表面硬化之應用。 奈米多層薄膜係將不同鈦鋁（TiAl）成分比例的靶材以及鉻（Cr）、鋯（Zr）靶材相對錯置於蒸鍍腔體的電極之間，同時導入四甲基矽烷（Tetramethylsilane，TMS；Si(CH3)4）做為碳（C）與矽（Si）的摻雜前驅物製備而成，並利用奈米硬度儀、磨耗試驗機及刮痕試驗評估膜層的機械特性，膜層之微觀結構與組成則採用電子微探儀、X光繞射、X光光電子光譜、掃描式電子顯微鏡與高解析穿透式電子顯微鏡等分析之。 實驗結果顯示，利用Ti0.33Al0.66高鋁鈦比靶搭配傳統工業使用的Ti0.5Al0.5鈦鋁靶可製備出Ti0.5Al0.5N/Ti0.33Al0.66N奈米多層氮化物薄膜，並可有效提升薄膜硬度達43.9 GPa，此一多層薄膜同時保有原始TiAlN膜的高溫硬度特性。利用Zr及Cr靶並藉由試片的轉速與電弧電流的控制可製備不同雙層週期厚度與層間比例的奈米多層氮化物薄膜，過去實驗結果顯示CrN/ZrN奈米多層薄膜在雙層週期厚度達到16 nm時有最佳硬度表現；同時C摻雜的最佳製程空間介於3.5-3.7 at.%。利用TMS做為C與Si的摻雜前趨物導入電弧蒸鍍腔中可成功製備出摻雜C與Si之CrSiCN/ZrSiCN奈米多層薄膜，並有效提昇先前CrN/ZrN奈米多層薄膜的硬度（25.2 GPa）與耐刮強度，透過工作壓力與氬氣（Ar）的流量調整同時可提升奈米薄膜的附着性與硬度（31.1 GPa）。

Due to the miniaturization and high-frequency applications of microelectronics, the substrates for electronic package have evolved from conventional FR4 printed circuit board to advanced substrates such as BT resin, Al2O3 and AlN substrates. Presently, the dry machining is the mainstream of substrate manufacture due to the requirements of product functionality and environmental issues. Development of new materials and surface hardening methods for drilling tools is hence critical since traditional cement metal tools such as WC-Co and surface coatings can no longer fulfill the precision of advanced substrate production. Nano-multilayered coatings are known to possess high hardness and high-temperature oxidation resistance in comparison with traditional single layered coatings. This thesis work investigates the nano-multilayered thin films prepared by filtered cathodic arc evaporation (CAE) method so as to explore their applicability to the surface hardening of cutting tools for dry machining. Nano-multilayered thin films were prepared by interleaving the Ti-Al targets with various composition ratios and Zr/Cr targets at different cathode locations of CAE system. Meanwhile, acetylene (C2H2) and tetramethylsilane (TMS, Si(CH3)4) was introduced during the deposition to supply of carbon (C) and/or silicon (Si) dopants in coating layers. The mechanical properties of coatings were evaluated by nano-indentaion, wear test and scratch test. Microstructures and compositions of samples were characterized by electron probe micro-analyzer, x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy and high-resolution transmission electron microscopy. Experimental results indicated that the Ti0.33Al0.66N/Ti0.55Al0.55N nano-multilayered thin film with the hardness as high as 43.9 GPa can be achieved by using a combination of an Al-rich Ti0.33Al0.66 target and a traditional Ti0.55Al0.55 target. Notably, such a hard coating layer provided a high hot hardness behavior compared with conventional TiAlN coating. The CrN/ZrN multilayered coatings with different bilayered thicknesses were also prepared by varying the substrate rotation speeds and the arc currents of the Cr/Zr target, and the best properties are achieved when the bilayered thickness is 16 nm and coatings containing 3.5 to 3.7 at.% of C. Bases on previous results, this thesis investigated the effects of TMS as the precursors of C and Si dopants. The process window using TMS was found to be wider than that of the acetylene method. The optimal hardness value (31.1 GPa) was achieved at the coating layer with the composition of 20.2% Cr-26.4% Zr-48.1% N-1.3% Si-2.2% C-1.8% O (in the unit of at.%) prepared at the 50 sccm flow rate of TMS. Meanwhile, the investigation on the influence of working pressure and argon (Ar) flow rate on hardness, adhesion and friction properties of coatings indicated that the lower friction could be achieved by increasing the Ar flow rate and the adhesion could be improved by slightly increasing the working pressure.