直流脈衝大氣壓電漿噴流薄膜塗布線上監控

In‐process Monitoring of Atmospheric Pressure Pulsed Plasma Jet on Thin Film Deposition

姜愷傑(Kai-Chieh Chiang)

指導教授 ： 蔡曜陽

國立臺灣大學/工學院/機械工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201700190

摘要

本研究為利用直流脈衝驅動的大氣壓電漿噴流系統(Atmospheric pressure pulsed plasma jet, APPJ)塗布氧化鋅摻鎵薄膜(GZO)。此系統有別於以往的在低壓下 的電漿輔助化學氣相沉積(PECVD)鍍膜，本系統在大氣壓環境下省去昂貴的真空設 備。透過柵型掃描平台，本系統可以對小面積到大面積的試片進行鍍膜。本研究針 對製程間進行品質監控，擷取進入電漿噴頭的電壓與電流進行分析來估算電漿密 度，也量測電漿餘輝的溫度及出口長度判斷電漿品質，透過電漿密度及餘輝觀察來 對最後的鍍膜品質進行評估，另外我們也發現電壓電流之間的相位角亦可當作品 質的判斷參考，最後整合以上資料能夠做到在製程間進行監控。
針對影響電漿狀況的主氣流、輸入電壓及輸入脈衝進行電訊號診斷，發現當主 氣流越小時，估算的電漿密度最高，此時餘輝長度也最長溫度也最高，而相位角最 低，最後片電阻值最低。而調整脈衝組合發現脈衝開啟時間 Ton 越長估算的電漿密 度越高，此時餘輝溫度也越高噴出長度也越長，最後所得片電阻越低。輸入頻率因 涉及脈衝關閉時間 Toff，其較不與利用開啟時間的電壓電流來估算的電漿密度有關 聯。不過越高的頻率其相位角越低，且相位角低於 1°時片電阻值最低。輸入電壓 的部分本研究發現電壓與輸入頻率為相依關係，不同的頻率下有最好的輸入電壓 能得到最佳片電阻。在輸入電壓為 160、180 及 200V 時改變頻率所量測到的相位 角與最後薄膜片電阻成相同消漲趨勢，最低片電阻都出現在相位角最低時的頻率， 此時電漿餘輝溫度也最高，噴出長度也最長，而當下的頻率為該輸入電壓下的製程 最佳頻率。改變 pins 實驗中顯示 pins 全部退出後可以得到較佳片電阻，但此時因 氣流通過較快，估算出來的電漿密度反而較低。最後大面積長時間鍍膜穩定度觀察 實驗，估算的電漿密度的波動僅 7%，且最後的片電阻值符合工業標準。

關鍵字

大氣壓電漿噴流 ； 氧化鋅薄膜 ； 電漿密度 ； 相位角 ； 電漿餘輝

並列摘要

This study is focused on atmospheric pressure plasma jet (APPJ) system which is driven by direct current pulses and deposits thin film of zinc oxide doped with gallium. This system, however, is different from low pressure plasma‐enhanced chemical vapor deposition (PECVD). This works under atmospheric environment; therefore, cost of vacuum pump system is avoided. With the grid‐shaped path, this system is covered varying size of thin film area. This study aims on in‐time monitoring of the process. Plasma density is estimated by analyzing the voltage and current signals into nozzle head. Plasma status is also determined by plasma afterglow with temperature and outlet length. Plasma density and afterglow are used to evaluate the quality of thin films. Moreover, phase angles between voltage and current is observed to be a reference to the processing quality. With all the data combined, it is able to establish in‐time process monitoring.
Plasma diagnose by input main gas, voltage and pulses is focused in this thesis. While lower the main gas flow rate, the estimated plasma density is higher and same to the afterglow length and temperature. On the other hand, phase angle is lower and thus the sheet resistant is lower. As for the input pulses, while pulse‐on time, Ton, is longer, the estimated plasma density is higher, as well as the afterglow length and temperature is higher. Therefore, the sheet resistant is lower. However, the pulse frequency is not related to the estimated plasma density, which is analyzed by electrical signals during Ton while frequency is associated with Toff, the pulse‐off time. Despite this, as the input frequency increasing, the phase angle decreases. The lowest sheet resistance is
observed while the phase angle is under 1°. The input voltage is found to be related with the input frequency in this study, as that the pulse frequency for lowest sheet resistant varies with the different input voltage. While the input voltage is 160, 180 or 200V, as the different frequency input, the phase angles and sheet resistances are in the same trend. The lowest resistances of thin films are all found under the lowest phase angle of electrical signals, the hottest afterglow and the longest length of afterglow. The frequency at this moment is seen to be the best for the process. At the experiment of pins, the lowest sheet resistance is found when pins are out of the nozzle. Nevertheless, the gas flow rate is high when without pins, thus, the estimated plasma density is low. At the end of the study, the steady of process is examined with large area deposition. The estimated plasma density varies within 7% and the result of sheet resistance meets the manufacturing standard.

並列關鍵字

Atmospheric pressure plasma jet ； Zinc oxide thin film ； Plasma density ； Phase angle ； Plasma afterglow

參考文獻

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