以超高頻(40.68 MHz)電漿輔助化學氣相沉積系統成長微晶矽薄膜之研究

Study on Very High Frequency (40.68 MHz) PECVD Growth of Microcrystalline Silicon Thin Films

金崇碩(Tsung-Shou Chin)

指導教授 ： 黃金花

國立清華大學/工學院/材料科學工程學系/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00287

摘要

本論文探討利用超高頻電漿化學氣相沉積(VHF-PECVD)在不同製程壓力、電漿功率、氫流量、矽甲烷流量與溫度下成長微晶矽薄膜，並分析微晶矽薄膜的鍍膜速率、結晶率、晶粒大小、能隙及電導率以利將來用於矽薄膜太陽能電池。
在微晶矽薄膜太陽能電池內，本質微晶矽薄膜為主要產生電子電洞對處，所以其薄膜特性對於矽薄膜太陽能電池極為重要，又因微晶矽薄膜吸收係數小，需要較厚的厚度才能產生較多的電子電洞對，所以沉積速率會影響微晶矽太陽能電池製造成本，在本實驗以本質微晶矽薄膜的沉積速率來看，最快速率發生在製程壓力4torr、電漿功率400W、氫流量600sccm、溫度200℃、矽甲烷流量40sccm時。本實驗中結晶率最大時發生在製程壓力7torr、電漿功率300W、氫流量1000sccm、溫度200℃、矽甲烷流量30sccm時。依據不同條件可調變能隙範圍在1.4eV~2.0eV。電導率愈高，使得在本質微晶矽薄膜的載子傳輸較不受阻而能達電極形成較大的光電流，電導率最高時發生在製程壓力2torr、電漿功率300W、氫流量400sccm、溫度300℃、矽甲烷流量15sccm時。由本實驗結果看來本質微晶矽薄膜在製程壓力4torr，電漿功率400W，氫流量600sccm，溫度200℃，矽甲烷流量15sccm時有較好的特性。

關鍵字

微晶矽 ； 超高頻電漿

並列摘要

In this thesis, the effects of process pressure, plasma power, hydrogen flow rate, silane flow rate and temperature on the growth of three kinds of silicon thin film, i.e. intrinsic microcrystalline, p-type and n-type silicon thin film via very-high-frequency PECVD (VHF-PECVD) were systematically discussed. Moreover, various electrical and structural properties such as deposition rate, crystallinity, grain size, energy band gap, conductivity, doping concentration and diffusion length were investigated thoroughly for the application of silicon thin film solar cells.
On the basis of literature, the deposition rate and crystallization are important factors to affect the performance of silicon thin film. Hence, these two parameters provide a starting-point in our study. The largest deposition rate was found to be a process pressure of 4 torr, plasma power of 400W, hydrogen flow rate of 600sccm, temperature of 200℃ and silane flow rate of 40sccm. Moreover, the best crystallization was found to be a process pressure of 7torr, plasma power of 300W, hydrogen flow rate of 1000sccm, temperature of 200℃ and silane flow rate of 30sccm. Energy band gap could be varied from 1.4eV to 2.0eV under different environment. The transportation of carriers between intrinsic microcrystalline silicon thin film and solar cell electrode is better for the higher electrical conductivity to generate large photo-current. The highest electrical conductivity was observed to be a process pressure of 2 torr, plasma power of 300W, hydrogen flow rate of 400sccm, temperature of 300℃ and silane flow rate of 15sccm. The optimum behavior was performed in a process pressure of 4 torr, plasma power at 300W, hydrogen flow rate of 600sccm, temperature of 200℃, silane flow rate of 15sccm.

並列關鍵字

microcrysatlline silicon ； VHF

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