The study of atmospheric pressure plasma for surface cleaning

In this study, capillary dielectric-covered dielectric barrier discharge was used to generate atmospheric pressure plasmas. The effect of various gas combinations such as He+O2, (He+O2)/Ar, and (He+O2)/SF6 was studied with respect to the changes in contact angle, surface energy and photoresist etch rate (ER). By adding a small percentage of O2 (40 sccm) to He (4 slm), we observed the increase in photoresist ER and the reduction of contact angle compared with the as-received sample. The effect of adding SF6 to the optimized He/O2 did not show any improvement in the contact angle. When SF6 was added more than 40 sccm, deposition has occurred instead of etching. The contact angle of the glass surface was decreased from 30° to 9.5–11° after cleaning with He/O2 based plasmas for 5–30 s. The lowest contact angle of 9° with the higher photoresist ER of 210 nm/min was obtained with (4 slm He+40 sccm O2)/Ar (20 sccm) at 400 W of alternating current power. Using He/O2/Ar based plasma to treat indium tin oxide (ITO), Ag, and polycarbonate surface, the contact angle is decreased, while the surface energy is increased. The contact angle decreased 78% for ITO deposited on the glass, decreased 24% for Ag patterned on the ITO, and decreased 70% for polycarbonate as-received samples. And the surface energy increased 46% for ITO deposited on the glass, increased 7% for Ag patterned on the ITO, and increased 68% for polycarbonate.