TE模式電子迴旋共振化學氣相沉積之矽薄膜電漿光譜研究

The optical emission spectroscopic study of silicon thin film deposited by TE mode Electron Cyclotron Resonance Chemical Vapor Deposition

吳昭穎(Chao Ying)

指導教授 ： 利定東

國立中央大學/工學院/能源工程研究所/碩士(2011年)

摘要

本研究利用電漿放射光譜儀(Optical Emission Spectroscopy, OES)探測電子迴旋共振化學氣相沉積儀(ECR-CVD)之製程電漿光譜並試與沉積薄膜特性做對照分析找尋其相對關係。在不同電漿功率、操作壓力、溫度及氫稀釋濃度下利用電漿放射光譜儀(OES)探測不同本質矽薄膜製程中之關鍵電漿物種Si*(288nm)、SiH*(414nm)、Hβ*(486nm)、Hα*(656nm)之原始強度並與Ar比較其相對物種濃度變化；接著配合電漿光譜與沉積薄膜的特性及沉膜速率作對照分析。
光譜探測結果發現在所有製程參數中以功率為最主要影響電子密度的因素，電子溫度則無太明顯變化，並且控制主磁場改變不同共振區間可得不同物種濃度分布；壓力部分，Ar光譜隨壓力增加六倍而下降90%，顯示電子密度會隨製程壓力增加而持續下降，電子溫度則隨製程壓力增加先劇烈下降5mtorr後逐漸趨緩；由薄膜沉積速率隨溫度下降可知ECR的沉膜反應屬於質傳限制反應；氫稀釋率部分，氫氣濃度愈高結晶現象越明顯且Hα*/SiH*＞6.5微晶開始產生，氫離子的迴旋共振也對電漿解離造成影響。
實驗可得，於45/12/22磁場組態下，功率1400W、壓力5mtorr、溫度350℃可得氫含量小於20%、R* <0.13的非晶矽薄膜。

關鍵字

矽薄膜 ； 電子迴旋共振化學氣相沉積 ； 電漿光譜 ； 光放射光譜儀

並列摘要

This study utilized Optical Emission Spectroscopy (OES) to diagnose the plasma spectrum by electron cyclotron resonance chemical vapor deposition (ECR-CVD) and tried to find out the relationship with the deposition properties. Under varying process setting , characterization by OES reveals the original intensity of the pivotal radicals spectrum: Si*(288nm), SiH*(414nm), Hβ*(486nm), Hα*(656nm). Moreover, we use the Actinometry technique to compare the species concentration with Ar’s and then analyze the thin film properties and the deposition rate with plasma spectrum.
The result showed that power was the major effect of process parameters on plasma density, but not on the electron density. The different species distributions were obtained by controlling the main magnetic field. The Ar spectrum intensity decreased 90% with adding six times the pressure, which revealed that the electron density would decrease continually and the electron temperature tended to decrease seriously from 3mtorr to 5mtorr then at ease by increasing working pressure. Because of the deposition rate decreased followed by increasing the temperature, ECR belonged to mass transfer limited reaction. Since high hydrogen dilution ratio, the crystallization phenomenon was obvious and microcrystalline silicon started from Hα*/SiH* > 6.5. Incidentally, the cyclotron resonance of H+ will have an influence on plasma.
Therefore, seeing from the experiments that the amorphous silicon film with CH < 20% and R* <0.13 could be obtained under 45/12/22, 1400W, 5mtorr, 350℃.

並列關鍵字

ECR-CVD ； OES ； silicon thin film ； plasma spectrum

參考文獻

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