Basic Research On Characteristics And Maskless Etching Of Atmospheric Pressure Cold Micro-plasma Jets

Atmospheric pressure micro-cold plasma jet is no-equilibrium plasma jet, which diameter size is from few millimeters to few sub-millimeters. On the basis of summarizing the research status of atmospheric pressure cold plasma jets and their applications on semiconductor etching, and learning the principles and properties of gas discharge, four micro-cold plasma jet sources of different structure are designed, and the characteristics of the plasma jets and their using on the SiC maskless etching are also studied.On the basis of analyzing the discharge characteristics of corona discharge and DBD under atmospheric pressure, the paper did the comparison among the cold plasma jets generated by different power supplies and working gases (N2, Ar and He). The results show that cold plasma jets of N2with bare electrode, Ar and He with DBD can be long, thin and stable.To find the effects on jets’size and temperature, various discharge parameters are tested on needle-cylinder and capillary-hole bare electrode configurations. The length and temperature of the jets generated by needle-cylinder configuration are10mm and15～19℃while the capillary-hole’s jet are20mm and28～67℃. And the preferable parameters of needle-cylinder are:the distance of electrodes is1.5mm. the diameter of central hole of nozzle is3mm, nitrogen flow rate is13L/min and discharge voltage is1.65～2.45kV; the preferable parameters of capillary-hole are:the distance of electrodes is1mm, nitrogen flow rate is3.3L/min and discharge voltage is1.47～1.82kV.The characteristics of cold plasma jets generated by capillary-ring and needle-ring DBD configurations with different parameters are studied. To the capillary-ring configuration, when the distance of electrodes is0.9mm, the distance between ring electrode and nozzle is3mm, the flow rate of Ar and He is respectively0.4L/min and1.2L/min, the discharge voltage is respectively1.0～3.2kV and0.7～3.1kV, it can produce stable micro-cold plasma jets of which length and temperatures are respectively15mm,19～52℃and18mm,20～29℃. To the needle-ring configuration, when the distance of electrodes is0.9mm, the flow rate of Ar and He is respectively0.2L/min and0.6L/min, the discharge voltage is respectively1.1～3.2kV and0.9～3.15kV, it can produce stable micro-cold plasma jets of which length and temperatures are respectively17mm,19～43℃and18mm.20～47℃.Under the assistance of mixed etching gas which composed by SF6and O2, the N2cold plasma jets generated by needle-cylinder bare electrode, Ar and He cold plasma jets generated by capillary-ring DBD are used to etch SiC without mask. The results show that the N2plasma jets can’t etch effectively, while the DBD plasma jets can obtain a micro-pit which diameter is less than0.8mm and the etching rate is nearly200nm/min.