類鑽碳膜應用於抗反射及疏水、疏油行為之研究

A Study of DLC Films for Coatings Application in terms of Anti-reflection and Water and Oil Repellent

張建國(Chien-Kuo Chang)

指導教授 ： 林啟瑞 ； 魏大華

國立臺北科技大學/機電學院/機電科技研究所/博士(2011年)

摘要

近年來在表面抗反射及疏水、疏油的工程技術是研究熱門的科學之一。其中，這些技術可能應用包含於顯示器、個人電腦(PC)、筆記型電腦及智慧型手機等。為了改善基板表面的光反射及同時具有疏水、疏油的特性，本論文以光學玻璃(D263T)作為實驗基板，並在其表面披覆類鑽碳(Diamond-Like Carbon, DLC)膜、氫氟醚(Hydrofluoroether, HFE)及表面次微米化(sub-micro-structures surface)之處理。在本研究過程中主要分為四個階段進行：(1)利用自製奈米鑽石靶材，並搭配RF非平衡磁控濺鍍系統（RF unbalanced magnetron sputtering），以低溫及大面積的方式製備出碳鑽碳膜。其中，本研究中為了有效找出最佳化的濺鍍製程參數，利用田口實驗設計法找出RF功率、工作距離、工作壓力及沉積時間等參數對類鑽碳膜的光穿透率的影響；(2) 將氫氟醚溶液，以沉浸法(dip coating )製作氟化層；(3) 利用CF4電漿蝕刻法製作次微米結構表面的類鑽碳膜；(4)將完成次微米結構的類鑽碳膜表面披覆一層氟化層。為了探討在不同製程參數及製程方法，對薄膜性質的影響，本研究利用掃描式電子顯微鏡(SEM)、X光光電子能譜儀(XPS)、奈米壓痕儀(NIP)、拉曼光譜(Raman spectrometer)、原子力顯微鏡(AFM)、紫外光/可見光光譜儀(UV/vis spectrometer)及接觸角分析儀等，分析其結構與機械性質及光學性質。本論文之研究結果，由SEM觀察在D263T玻璃的表面披覆單層的類鑽碳膜後，其表面形貌仍然相當平整，不會因類鑽碳膜本身內應力較大的缺點，所造成濺鍍的類鑽碳膜產生裂痕。AFM分析範圍為30× 30 μm2條件下，D263T玻璃基板經披覆類鑽碳膜後其表面平均粗糙度(rms)均小於1.86 nm；利用NIP測試D263T玻璃基板經披覆類鑽碳膜的奈米壓痕硬度值範圍介於13.2至22.5 GPa，其硬度值均高於未鍍膜基板的6.86 GPa；由去離水(DI water)作為液滴，所測得類鑽碳膜的接觸角均高於未鍍膜D263T玻璃基板，接觸角增加145%。由本實驗結果發現，類鑽碳膜的硬度及疏水性，隨著薄膜的sp3含量的增加而增加。更進一步， 利用田口實驗設計法找出最佳化類鑽碳膜的sp3含量、表面粗糙度(rms)、疏水性及光學特性。在最佳化實驗設計中，沉積時間10分鐘條件下，D263T玻璃基板經披覆單層的類鑽碳膜後，其sp3含量高於56%、表面粗糙度(rms)及疏水性分別為1.925 nm與94o。光平均穿透率在可見光範圍為90%。在氟化層及次米化結構表面的類鑽碳膜，其疏水及疏油的接觸角分別高於115o及68o，但表面經次米化結構的類鑽碳膜之光穿透率，隨著四氟甲烷(carbon tetrafluoride)蝕刻的時間增加而光穿透率降低。為了提昇光穿透率，本論文利用Essential Macleod光學軟體，設計抗反射的多層漸變式折射率的類鑽碳膜。由模擬結果顯示，兩層的類鑽碳膜在波長500 至950 nm之間，平均光穿透率為93.97%；三層漸變式折射率的類鑽碳膜，平均光穿透率為97.14%。因此，利用四分之一及二分之一波長，折射率範圍從1.56至2.09，膜厚在355 nm之多層漸變式折射率的類鑽碳膜披覆在玻璃上，在理想設計上可達到抗反射的效果。本實驗中在D263T 玻璃表面上披覆類鑽碳膜的濺鍍製程參數，對其物理及光學特性有顯著的影響。其中，以濺鍍的功率及沉積時間為主要影響類鑽碳膜的特性因素。從本論文之研究結果，類鑽碳膜可提供其在光電元件應用的可行性。

關鍵字

類鑽碳膜 ； 抗反射膜 ； 疏水 ； 疏油 ； 氫氟醚 ； 次微米結構表面 ； 田口實驗設計法 ； D263T玻璃

並列摘要

It is important that recent researches and technology focus on keeping the surface water and oil repellent as well as improving the surface lower reflection, and their potential applications in optoelectronic devices, for instance, monitors, personal computers (PCs), notebooks, smartphones and so on. This research aims to improve the surface lower reflection along with the surface water and oil repellent. Diamond-like carbon (DLC) films, Hydrofluoroether (HFE), and sub-micro- structures surface of DLC film are coated onto D263T glass which was used as the substrate. This dissertation describes here a four-step method for anti-reflection and water and oil repellent coatings. First, hydrogen-free DLC films were deposited on substrates at room temperature by rf magnetron sputtering system with a pure diamond powder target in an Ar plasma. To find the parametric optimization of DLC Films for a high light transmission, this study employs Taguchi methods to design the experiment of the as-deposited hydrogen-free DLC films. The surface of substrates is then fluorinated by dip coating in Hydrofluoroether (HFE) solvent. Third, as sub-micro-structures surface, the textured surfaces of DLC films are formed by using the CF4 plasma etching. Finally, sub-micro-structures surface of DLC films are deposited on the surface of predeposited fluorination layer. Purposing this work is to deposit hydrogen-free DLC films on substrates at various process parameters to tune the properties of the DLC films. The corresponding microstructure, optical performance, and mechanical properties of DLC films were identified by scanning electron microscope (SEM), X-ray photoemission spectroscopy (XPS), NIP, Raman spectroscopy, Atomic force microscopy (AFM), UV/vis spectrometer, contact angle goniometry, and fractal analysis measurements, respectively. From SEM results, the plan view surface of DLC films are smooth morphology and those films do not affect the cark on the surfaces, owing to as-deposited DLC films easily form the high internal stresses. AFM surface topography for DLC/D263T glass indicates that the average rms roughness is 1.86 nm below with scanning area of 30×30 μm2. The NIP test results show that the hardness behaviors of all as-deposited single layer DLC films onto D263T glass are ranging from 13.2 to 22.5 GPa, and its hardness is larger than that of the non-coated of 6.86 GPa. Also, it is found that the water contact angle of single layer DLC films on coated D263T glass are improved significantly with an increase of 145% via DI water droplets. The aforementioned hardness and wetting test results showed that the hardness and hydrophobic behaviors of all as-deposited DLC films improved significantly with the increase of the sp3 content. Moreover, the sp3 content, surface roughness (rms), water contact angle (CA) , and optical properties of the optimized parameters of single-layer DLC film with using Taguchi methods could be controlled by regulating deposition time. The DLC films deposited at deposition time of 10 mins with a high sp3 content of as high as 56% were realized with a surface roughness and contact angle of 1.925 nm (rms) and 94°, respectively. Ultraviolet/visible (UV/vis) spectrophotometry of single-layer DLC films showed a high transmissive ability (＞90%) in the visible wavelengths. The water and oil contact angles of the HFE/Sub-micro-structures surface of DLC films are above 115o and 68o, respectively. However, the low transmittance shows the etching time of carbon tetrafluoride (CF4) plasma treatment increased accordingly. Furthermore, the high transmittance of DLC film was designed by Essential Macleod software. In this research, simulated multilayer anti-reflection coatings based on the refractive index limits of DLC films on glass are presented. From simulated results, the double-layer anti-reflection coatings show that the average transmittance of 93.97 %, the absorption wavelength (λ) is between 500 nm and 950 nm. The best structure design of three layers DLC films resulting in the average transmittance of 97.14%. Therefore, good results are designed the quarter-half-quarter coating. In this case of three layers DLC films obtained with values of the index in the range 1.56-2.09 and the total thickness of 355 nm. The quarter-half-quarter coating is certainly the most significant of the multilayer coatings for low-index glass. Above results confirm that sputtering process parameters are an important factor in the nanotribological characteristics and fractal analysis of DLC films deposited on D263T glass substrate. The investigations reported here show the importance of deposition power and deposition time in tuning the properties of the DLC films. These results suggest useful information for the development of modern applications of optoelectronic devices.

並列關鍵字

Diamond-like carbon ； anti-reflection ； water and oil repellent ； Hydrofluoroether ； sub-micro-structures surface ； Taguchi method ； D263T glass

參考文獻

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