脈衝線性電感式耦合電漿源研製與實驗量測分析

Experimental Analysis of a Pulsed Inductively Coupled Linear Plasma Source

蕭偉銘

指導教授 ： 柳克強

國立清華大學/原子科學院/工程與系統科學系/碩士(2013年)

https://doi.org/10.6843/NTHU.2013.00459

摘要

本論文之研究目的，在於研製脈衝線性電感式耦合電漿源，並對此線性電漿源系統進行各項電漿參數的量測，由隨時變之電漿特性參數分析脈衝線性電漿源的物理機制與特性。
本研究成功研製出脈衝線性電感式耦合電漿源，並修改與使用脈衝電漿源的量測系統。以蘭牟爾探針量測在不同操作條件下的隨時變電漿特性參數，使用射頻阻抗計量測脈衝電漿之射頻電性。
由射頻阻抗計量測結果顯示，射頻電壓中，隨工作比例、脈衝頻率增加沒有明顯關係，隨壓力增加有明顯的下降關係；射頻電流中，隨脈衝頻率改變沒有明顯變化趨勢，隨著工作比例、壓力的增加而下降。在脈衝開的初期，阻抗有一個峰值，是因為剛開始時是由電容式耦合轉變到電感式耦合的關係。
蘭牟爾探針量測結果顯示，脈衝電漿密度隨與天線距離增加時會有先增後減的現象，靠近天線會比較低是因為擴散損失(diffusion loss)較多，而脈衝電漿密度在工作比例為70%時有最大值，為9.24 × 10^10 cm^-3，其平均電漿密度為7.87 × 10^10 cm^-3。另一方面，脈衝電漿在相同的吸收功率下，有較高的平均電漿密度(連率電漿：吸收功率為192 W，電漿密度為6 × 10^10 cm^-3)。
在電子溫度方面，脈衝開時有一個較大的峰值，是因為脈衝開的瞬間，功率大幅增加的影響，電子溫度在靠近天線的位置有最大值，隨著與天線距離增加而減少，這樣的趨勢與文獻、預期符合，但電子溫度的值卻過大，比較不合理，是因為射頻信號干擾影響，使分析產生誤差。

關鍵字

脈衝線性電漿 ； 電感式耦合電漿源 ； 脈衝電漿

並列摘要

The purpose of this study is to develop a pulsed inductively coupled linear plasma source, and analyze the temporal and spatial behavior of plasma characteristic parameters. In this research, we has successfully developed a pulsed inductively coupled linear plasma source. We modify and use measurement systems for a pulsed plasma source. We measure the temporal and spatial behavior of plasma parameters by using Langmuir probe and measure the rf parameters by using rf impedance meter (VI probe).
In the results of rf impedance meter measurement, the magnitude of rf voltage didn't change significantly as the duty cycle or pulsed frequency increases, rf voltage decreases as the pressure increases. The magnitude of rf current didn't change significantly as pulsed frequency increases, rf current decreases as the duty cycle or pressure increases. A spike of the real part rf impedance due to the transition from capacitive to inductive coupling is observed in the beginning of the modulation pulse.
In the results of Langmuir probe measurement, plasma density first increases and then decreases if the probe is moved away from the antenna, because there are more diffusion loss near the linear antenna. In the results, the plasma density at pulse mode is higher than that at continuous wave mode when they are operated at the same average power. In pulse mode, the highest average plasma density is 7.87 × 1010 cm-3 (10 mtorr, 70%, 10 kHz ). A spike of electron temperature due to the power increases substantially in the beginning of the modulation pulse. The magnitude of electron temperature has maximum, the electron temperature decreases if the probe is moved away from the antenna. Because there are interference of rf fieid in rf plasma, it make more error in electron temperature.

並列關鍵字

pulsed linear plasma ； inductively ； pulse plasma

參考文獻

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