容性耦合电负性氧等离子体的激光诱导光致剥离技术诊断研究
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摘要
采用波长532nm的高能脉冲激光束照射40.68MHz激发的容性耦合氧等离子体,并给处于激光束中央的探针施加一定的正偏压,由此诊断氧等离子体的空间电位和电负度。实验结果表明,探针偏压从0V逐渐增加时,探针搜集的电流波形从V型向倒U型转变,转变电压点正是电负性等离子体的空间电位。尝试着给出了运用激光诱导光致剥离技术诊断电负性等离子体空间电位的经验方法。另外,探针上施加的正偏压高于等离子体空间电位时,等离子体的电负度基本保持不变。实验还表明,氧等离子体的电负度随着射频输入功率的增加而呈现下降的趋势。
A high energy pulsed laser beam with wavelength of 532 nm was applied to irradiate the capacitively coupled O_2 plasma driven by 40.68 MHz. Spatial potential of the plasma and electro negativity are diagnosed by exerting a certain positive bias on the probe aligned with laser beam at the center. The experimental results show that a transition of signal wave shape on the probe occurs from V-shaped to invert U-shaped as increasing positive bias. The transition voltage point is just the spatial potential of electronegative plasma. An empirical method was given to obtain the spatial potential of negative plasma by using LIPD technique. Additionally, plasma electro negativity keeps a constant basically as increasing positive bias beyond the plasma spatial potential. The experiments still show a trend of decrease in electro negativity of O_2 plasma with increasing RF input power.
A high energy pulsed laser beam with wavelength of 532 nm was applied to irradiate the capacitively coupled O_2 plasma driven by 40.68 MHz. Spatial potential of the plasma and electro negativity are diagnosed by exerting a certain positive bias on the probe aligned with laser beam at the center. The experimental results show that a transition of signal wave shape on the probe occurs from V-shaped to invert U-shaped as increasing positive bias. The transition voltage point is just the spatial potential of electronegative plasma. An empirical method was given to obtain the spatial potential of negative plasma by using LIPD technique. Additionally, plasma electro negativity keeps a constant basically as increasing positive bias beyond the plasma spatial potential. The experiments still show a trend of decrease in electro negativity of O_2 plasma with increasing RF input power.
引文
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[3]Stamate E,Popa G,Ohe K.Test function for the determination of plasma parameters by electric probes[J].Rev.Sci.Instrum.,1999,70:58-62.
[4]Kang S Y,Chung T H,Chung K S.Three point method to characterize low-pressure electronegative discharges using electrostatic probe[J].Rev.Sci.Instrum.,2009,80:013502.
[5]Chabert P,Sheridan T E,Boswell R W,et al.Electrostatic probe measurement of the negative ion fraction in an SF6helicon discharge[J].Plasma sources Sci.Techn.,1999,8:561-566.
[6]Chung K-S,Kado S.Deduction of the absolute negative ion density by using planar and cylindrical electric probes simultaneously[J].Phys.Plasmas,2006,13:104509.
[7]Joh H M,Chung T H,Chung K S.Electrostatic probe measurement of low-pressure electronegative SF6discharges[J].Thin Solid Films 2010,518:6686-6689.
[8]Bacal M,Hamilton G W,Bruneteau A M,et al.Measurement of H density in plasma by photo detachment[J].Rev.Sci.Instrum.,1979,50:719-721.
[9]Bacal M,Berlemont P,Bruneteau A M,et al.Measurement of the H-thermal energy in a volume ion source plasma[J].J.Appl.Phys.,1991,70:1212-1219.
[10]Bacal M.Photo detachment diagnostic techniques for measuring negative ion densities and temperatures in plasmas[J].Rev.Sci.Instrum.,2000,71:3981-4006.
[11]Conway J,Sirse N,Karkari S K,et al.Using the resonance hairpin probe and pulsed photo detachment technique as a diagnostic for negative ions in oxygen plasma[J].Plasma Sources Sci.Techn.,2010,19:065002.
[12]Küllig C,Dittmann K,Meichsner J.A novel approach for negative ion analysis using 160 GHz microwave interferometer and laser photo detachment in oxygenicRF plasmas[J].Plasma Sources Sci.Techn.,2010,19:065011.
[13]Stoffels E,Stoffels W W,Vender D,et al.Negative ions in a radio-frequency oxygen plasma[J].Phys.Rev.E,1995,51:2425-2435.
[14]Dittmann K,Küllig C,Meichsner J.Electron and negative ion dynamics in electronegative cc-RF plasmas[J].Plasma Phys.Contr.Fusion,2012,54:124038.
[15]Katsch H M,Sturm T,Quandt E,et al.Negative ions and the role of detestable molecules in a capacitive coupled radiofrequency excited discharge in oxygen[J].Plasma Sources Sci.Techn.,2000,9:323-330.
[16]Vender D,Stoffels W W,Stoffels E,et al.Chargedspecies profiles in electronegative radio-frequency plasmas[J].Phys.Rev.E,1995,51:2436-2444.
[17]Dodd R,You S-D,Bryant P M,et al.Negative ion density measurements in a reactive dc magnetron using the eclipse photo detachment method[J].Plasma Sources Sci.Techn.,2010,19:015021.
[18]Oudini N,Taccogna F,Bendib A,et al.Numerical simulations used for a validity check on the laser induced photo detachment diagnostic method in electronegative plasmas[J].Phys.Plasmas,2014,21:063515.
[19]Oudini N,Sirse N,Benallal R,et al.Numerical experiment to estimate the validity of negative ion diagnostic using photo detachment combined with Langmuir probe[J].Phys.Plasmas,2015,22:073509.
[20]Sirse N,Karkari S K,Mujawar M A,et al.The temporal evolution in plasma potential during laser photodetachment used to diagnose electronegative plasma[J].Plasma Sources Sci.Techn.,2011,20:055003.