以大氣電漿進行薄膜表面處理之研究

A Study on the Surface Treatment of the Thin Films by Atmospheric Pressure Plasma Jet

許翰林(Han-Lin Sheu)

指導教授 ： 鄧治東

中原大學/工學院/機械工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200901175

摘要

光阻為半導體業常見之材料，但近年半導體業者紛紛尋找替代原料降低成本，聚亞醯胺則取代光阻成為常見之有機材料。稍早於工業蝕刻聚亞醯胺多數採用濕式蝕刻法，即採用化學溶液之方式進行蝕刻動作，但此舉易產生等方向性、深寬比較小之情況發生，又會造成環境之汙染。近年來新興電漿技術取代溼式蝕刻為工業之新寵，傳統電漿以真空設備為主，須配置腔體、真空幫浦等昂貴且耗時器材，大氣電漿噴頭可免除繁雜手續節省製程時間、降低成本。

　　本文以大氣電漿噴頭為出發點，採用電源功率、製程氣體流量、掃描次數為製程參數，並以實驗設計法製作15組參數探討參數與參數之間對於蝕刻之影響，並利用掃描式電子顯微鏡、原子力學顯微鏡了解薄膜表面形態。結果顯示，當電源功率增加時可有效增加蝕刻速率，但過高之功率易造成電極與試片溫度過高。製程氣體流量呈現先升後降之趨勢，過大之氣體流量會稀釋電子能量，反而造成蝕刻速率緩慢。掃描次數為三者中影響較小者，因當前兩者配合適當時即可有效的取代多次數掃描。

　　以計算流體力學軟體CFD-RC進行噴射式大氣電漿源之數值模擬。於輔助氣體管路通入不同流量之氧氣，比較後發現當輔助氣體加入製程後對於電極區之散熱極有幫助，且噴射式電漿源之幾何設計得以改善製程氣體集中不擴散。因此本研究藉計算流體力學軟體，迅速修改混合區之幾何，探討擴大、縮小氣體混合區之差別。結果顯示當縮小氣體混合區後氣體流速變快，電極區散熱程度提升，但氣流場狀態則不穩定。放大氣體混合區則氣體密度下降、熱流場穩定但電子溫度為三者最低，因而不利於製程。

關鍵字

計算流體力學 ； 實驗設計法 ； 聚亞醯胺 ； 電漿蝕刻

並列摘要

Polyimides (PI) have been widely used for semiconductor and opto-electronic industries due to their stability and durability. A few years earlier, people used chemical wet-etching to etch thin films, but there are shortcomings such as isotropy, low value of depth to width ratio, and generation of pollutants. Recently, plasmas replace wet-etching and become new stars in industry. But there are a few flaws that low-pressure plasma cannot overcome: limited process area in the chamber and the need of a vacuum pump to achieve the required condition. Atmospheric pressure plasma jet (APPJ) has been developed to correct the shortcomings and change the situation. It’s not only cheaper but also more efficient than the traditional plasma.
Based on APPJ, three parameters were selected, including power, flow rate, scan-time, together with three levels for each parameter. To examine the experimental efficiencies, surface response methodology (SRM) was used to find out relation between parameters and impact of parameters to the outcome of the APPJ treatment of the surface. Later, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to determine the surface morphology of the samples being tested. The experimental results showed that as the power is increased so does the etching rate, but overheat takes place when the imposed power becomes too large. Besides, excessive amount of gaseous flow rate results in the dilution of electronic power density, leading to a reduced etching rate. Furthermore, scan time is the least important parameters among the three being considered. The number of scan time can be ignored by a proper combination of the other two parameters, resulting in saving time during the plasma processing.

Numerical simulations of AAPJ were done by using the CFC-RC software package. Various amounts of oxygen were used in the auxiliary gaseous tube to help improve the heat-removal in the region where electrode was located. Improvement of the geometrical configuration of the plasma source helps focus the process gas to prevent it from scattering. The numerical method used in this study expedited the revision of the configuration where mixing occurred. In addition, variations in the size of the gaseous mixing region could be evaluated. The results obtained from this study indicated that as a result of shrinking the size of the gaseous mixing region, the gaseous flow rate became larger, leading to an enhanced dissipation of heat in the electrode region with an unstable gaseous condition. On the other hand, expanding the size of gaseous mixing region would result in a decrease in the gaseous density. For this aspect, the thermal field was stable but the electronic temperature was the lowest for the three cases being considered, leading to the least favorable condition for processing.

並列關鍵字

Experimental designs ； Simulation ； Atmospheric pressure plasma jet ； Polyimide

參考文獻

【4】黃文鵬, “利用大氣電漿束蝕刻PI膜之研究”, 國立清華大學物理學系光物組 碩士論文 (2007).

膜製程之研究＂, 中原大學 化學工程學系 博士論文 (2005).

【18】陳崑約, “以二維流體模型模擬分析電感耦合式電漿源之電漿特性均勻度之研究”, 清華大學 工程系統學系 碩士論文 (2008)

【6】陳泰宏, “探討PI 膜液晶配向製程之研究”, 中原大學機械工程學系機械所 碩士論文 (2006)

【7】劉志宏, “應用實驗設計法與電漿診斷技術探討電漿沉積氟碳