Characteristic of a dielectric barrier discharges using capillary dielectric and its application to photoresist etching

In this study, atmospheric pressure plasmas were generated using a dielectric barrier discharge equipment using capillary dielectric materials and the characteristics of the plasmas and the surface cleaning rate were studied as a function of He/O₂ gas mixture and electrode material. The use of capillary dielectric instead of blank dielectric increased the plasma density by effectively using the voltage sustained in the dielectric for accelerating electrons at the capillary holes, therefore, by forming ion beam-like plasmas at the holes in addition to typical dielectric barrier discharges. The addition and increase of oxygen into He decreased the plasma density monotonically due to the increased charge neutralization; however, oxygen atoms increased initially and showed a maximum with the increase of oxygen. The etch trend of photoresist, therefore the cleaning rate of organic materials, was related to that of oxygen atoms in the plasma. As capillary dielectric materials, the use of ceramics instead of Teflon showed higher photoresist etch rate with higher radical and plasma densities due to the higher sustaining voltage at the air gap between the electrodes.