氦氣及氙氣之添加對電感偶合式六氟化硫電漿性質影響之研究

A Comparative Study on the Effect of Helium and Xenon Addition to Inductive-Coupled SF6 Plasma

林以穠(E-Non Lin)

指導教授 ： 魏大欽

中原大學/工學院/化學工程研究所/碩士(2009年)

https://doi.org/10.6840/cycu200900876

摘要

本研究利用電漿放射光譜儀，探討電感偶合式SF6/He和SF6/Xe電漿性質(各物種濃度、SF6解離率等)隨操作參數之變化，並在不同基板面積、電漿功率、操作壓力及氣體配比下對矽晶圓進行電漿蝕刻，探討蝕刻速率之差異及其與氟原子濃度之關連性。
在電漿蝕刻方面，不同矽晶圓面積下，SF6/He電漿之矽蝕刻速率皆與以放射光譜所測得之氟原子相對強度趨勢類似，但在SF6/Xe電漿時，選擇不同F及Ar特徵峰進行半定量分析時，會與蝕刻速率有很大之差異，所以必須慎選其特徵峰才能與蝕刻速率作一比較。此外，在改變電漿功率時，SF6電漿添加He之後其氟原子濃度皆維持不變；解離率隨著He添加比例而上升，蝕刻速率則與氟相對強度趨勢類似。添加Xe後則會使氟原子濃度下降；解離率則大致維持持平之趨勢，同時Xe比例增加會使離子轟擊效應增強使得氟原子濃度與蝕刻速率有較大差異。接著在探討惰性氣體流量對蝕刻速率之實驗中，發現在較低功率且高壓力下，電漿性質會因電子密度較低而較趨於CCP mode，使得蝕刻速率較低，添加惰性氣體後能使電漿穩定而轉變為ICP mode，進而使蝕刻速率有效提升。
最後為了進一步提升蝕刻速率，所以針對SF6/O2系統添加惰性氣體加一探討，結果顯示在較低功率下，添加惰性氣體會使SF6/O2系統之電漿趨於穩定，所以使得蝕刻速率上升，而在較高功率下，因電漿一直保持在ICP mode，使得蝕刻速率無明顯變化。

關鍵字

蝕刻速率 ； 電漿蝕刻 ； 放射光譜

並列摘要

In this study, the characteristics (species concentration and SF6 conversion) of inductively coupled SF6/He and SF6/Xe plasma were investigated using optical emission spectroscopy. The effects of operating parameters (wafer area, power, pressure, and gas ratio) on plasma etching of silicon are discussed.
The plasma etching results show that the Si etch rate in SF6/He plasma has the same trend with the relative fluorine OES intensity, but it is different in SF6/Xe plasma. Careful choice of the characteristic peak must be done in SF6/Xe plasma to compare fluorine intensity with Si etch rate. The relative fluorine intensity was constant when He was added to SF6 plasma, and SF6 conversion increased with fractional He flow rate. Whereas for SF6/Xe plasma, the SF6 conversion was nearly constant when Xe was added to SF6 plasma, and the relative fluorine intensity decreased with fractional Xe flow rate. Under low power and high pressure conditions, the pure SF6 plasma was in CCP mode. When helium of xenon was added to SF6 plasma, the plasma changed to ICP mode and the silicon etch rate increased effectively.
In order to further increase Si etch rate, oxygen was added to SF6 plasma. The results show that plasma became stable when adding inert gas to SF6/O2 plasma under low power conditions, and the etching rate was enhanced significantly.

並列關鍵字

etch rate ； plasma etching ； optical emission spectroscopy

參考文獻

【2】 龍柏華,何孝恆“乾蝕刻製程暨機台原理簡介”,2004.9.53期

【1】 Kurt J. Taylor, Seokmin Yun, and George R. Tynan,“Control of plasma parameter by using noble gas admixture”, J. Vac. Sci. Tecchnol. A 22,5(2004)

【3】 Brian Cpapman,“Glow Discharge Process”,﹙John Wiley & Sons, Canada, 1980﹚.

【4】 鄭立群“以非熱電漿處理CF4及SF6之效率探討”, 國立中央大學環工所 碩士論文(2006)

【13】 J. W. Coburn ,“Plasma Etching and Reactive Ion Etching”, AVS Short Course Note(1980)