非晶矽薄膜製程於電子迴旋共振氣相沉積之電漿診斷研究

本研究使用光放射光譜儀(OES)監測電漿物種變化，蘭牟爾探針(Langmuir probe)監測電漿特性，四極柱質譜儀(QMS)監測物種濃度，於電子迴旋共振化學氣相沉積製備非晶矽薄膜之製程。調變的參數為微波功率、壓力、磁場共振位置、氫稀釋濃度比並輔以FTIR、Detek來探討薄膜的結構特性，以少數載子生命週期和微結構因子判斷薄膜品質的好壞。最後將電漿特性與薄膜特性相互比較，以期建構電漿診斷平台。經由實驗可得，考慮到電子密度及電子溫度的影響因此製程壓力選用5mTorr最為恰當；至於功率可選用低功率500W；綜合以上參數，可於磁場組態40/12/22、氫稀釋比0.2、厚度20nm下獲得品質穩定的非晶矽鈍化薄膜。本研究成功整合了OES、Langmuir probe、QMS，將SiH4消耗量、表面懸吊鍵數量作為預測薄膜沉積速率指標，使用SiH2/SiH3為薄膜品質之指標並將Si*/SiH*作為電子溫度指標。最後，以沉積非晶矽薄膜為例，解析ECR電漿沉膜機制。並可利用此結論，在尚未成長薄膜前，就先行營造出有利成長良好特性的薄膜生長環境，藉此減少製程之試誤時間。

關鍵字

電漿診斷；氫化非晶矽薄膜；四極柱質譜儀；光放射光譜儀；蘭牟爾探針

並列摘要

In this study, OES (Optical emission spectrometer), Langmuir probe, and QMS (Quadrupole mass spectrometer) were utilized as plasma diagnostics tools and a-Si:H (Hydrogenated amorphous silicon ) thin film was deposited by electron cyclotron resonance chemical vapor deposition (ECR-CVD). QMS and OES were used to identify active species in the plasma. Electron density, electron temperature and the energy of ion bombardment were obtained by Langmuir probe. The film quality such as microstructure fraction (R*), hydrogen content (CH), deposition rate, and lifetime were investigated by FT-IR and Detak. The relationship between the film quality and plasma characteristics with varying process parameters (microwave power, working pressure, magnetic field resonance position, and dilution ratio) was discussed. The result showed that high microwave power and high hydrogen flow rate injected would lead to higher electron temperature and more SiH2 generated in the plasma. Higher process pressure caused lower electron density and lower electron temperature. Therefore thin film with a low defect would be deposited by dilution ratio of 0.2, microwave power of 500W, working pressure of 5mTorr and the magnetic field configuration of 40A, 12A and 22A represented main coil, inner coil and outer coil current respectively. Consequently, we successfully demonstrate the mechanism of plasma in a-Si:H process and have some findings in which the consumption of SiH4 and the amount of dangling bond on the surface could be regarded as an indicator of deposition rate in a-Si:H process and the ratio of SiH2 to SiH3 from QMS could be considered as an indicator of film quality for microstructure fraction (R*) in films. Si*/SiH* from OES could be treated as an indicator for electron temperature in transport.

並列關鍵字

Plasma diagnostics ； hydrogenated amorphous silicon ； QMS ； OES ； Langmuir probe

參考文獻

[2]National renewable energy laboratory(USA), 2008, http://www.nrel.gov/.

[3]K. Arima, T. Shigetoshi, H. Kakiuchi, and M. Morita, “Surface photovoltage measurements of intrinsic hydrogenated amorphous Si films on Si wafers on the nanometer scale”, Physica B, Vol 376–377, pp. 893–896, 2006.

[4]Chapman, B., Glow Discharge Processes, John Wiley & Sons lnc, 1980.

[7]I. H. Hutchinson, Principles of Plasma Diagnostics 2nd, Cambridge University Press, 2002.

[10]J. Venables, “Nucleation and Growth of Thin films”, Rep. Prog. Phys., Vol 47, pp. 399, 1984.

國際替代計量

非晶矽薄膜製程於電子迴旋共振氣相沉積之電漿診斷研究

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