電漿表面改質之橢圓偏光分析

Analysis of Plasma Surface Modification With Ellipsometry

陳信吉(Sing-Ji Chen)

指導教授 ： 陳恕行

崑山科技大學/工程學院/機械工程研究所/碩士(2003年)

摘要

在電子產業中為確保清潔度及結合性，應用電漿來進行清洗與表面改質的需求愈來愈普遍。許多生化材料也常用電漿改質使表面接上具有不同特性的官能基。對原本接著性較佳的表面，如金屬表面，電漿作用主要是去除有機污染膜，而對原本接著性的較差的表面，如高分子表面，電漿作用則是使表面活化。
對於電漿處理後的表面檢驗，可以水滴角計量測其表面自由能，電漿處理後表面極性會增加使接觸角減小。光學的方式可提供膜厚及折射率等資訊。另外ESCA、Auger等儀器可用來做表面微結構檢測及成份分析。由於電漿清洗與表面活化的效果通常不能持續很久，水滴角計與光學的方式較適合在現場對改質表面做量測。
本研究主要探討橢圓偏光的光學檢驗方式，橢圓偏光法是量測角度及相位的改變，與光強度無關，可得到很精準量測。本研究主要是要瞭解用在IC封裝中不同材料經電漿改質後的橢圓偏光Y、D 角度之變化，以作為線上量測之參考，所用的試片是黏於IC晶片背面的鋁製散熱片與塗有Epoxy防焊漆的BGA 基板。
橢圓偏光法對於有明顯分層的試片，曲線嚙合(curve fitting)可很容易完成。但電漿表面改質後的表面並無明顯分層，所以本研究探討如何利用誤差函數的分佈來做曲線嚙合。

關鍵字

橢圓偏光儀 ； 電漿表面改質

並列摘要

Low-pressure plasma is increasingly used in the IC industry for cleaning and the modification of interface for improved adhesion. Plasma processing, an effective, economic and environmentally safe method, is often used in the final cleaning procedure. For a metallic surface, plasma cleaning removes organic contamination or metal oxide. For polymers, plasma activates the surface for subsequent joining and molding procedures. Plasma are also used to obtain hydrophilic, hydrophobic, or bio-compatible surfaces for biomaterials.
The treated surface demonstrates a dramatic increase in surface energy, which can be easily determined with contact angle measurement. Ellipsometry, however, provides a way to further characterized the treated surface, e.g. film thickness, refraction index n and extinction coefficient k. Ellipsometry is sensitive since it is free from the disturbance of light amplitude by only taking into account of the change in the two angle Y and D, related to the ellipticity of polarized light. Ellipsometry can be adapted to in-situ measurement.
A major concern with the technique of ellipsometry is the best way to extract information from a data set. A single pair of ellipsometry parameters Y and D can be inverted analytically to determine two unknowns. But for plasma treated polymer surface, which does not have clear layered structure, a curve-fitting technique using the erf function profile is studied.
Experiments have been carried out for the treatment on BGA substrates and metallic heat sinks with a RF plasma source. The ellipsometry is measured with incident angles between 55° and 80°.

並列關鍵字

Ellipsometry ； Plasma Surface modification

參考文獻

4.彭崑彰,陳恕行,"錫球迴焊成型分析及動態顯示",第16屆全國技術及職業教育研討會研討會論文集

6.B. Kegel , H. Schmid , "Low-pressure plasma cleaning of metallic surfaces on industrial scale ," Surface and Coatings Technology 112 (1999) , 63–66.

7.C. Lee , R. Gopalakrishnan , K. Nyunt , A. Wong , R.C.-E. Tan,J.W.-L.Ong,"Plasma cleaning of plastic ball grid array package," Microelectronics Reliability 39 (1999),97-105.

8.E.I. Meletis , X. Nie , F.L. Wang , J.C. Jiang , "Electrolytic plasma processing for cleaning and metal-coating of steel surfaces ," Surface and Coatings Technology 150 (2002) , 246–256

9.H. Kupfer , G.K. Wolf , "Plasma and ion beam assisted metallization of polymers and their application ," Nuclear Instruments and Methods in Physics Research B 166-167 (2000) , 722-731.