THE STUDY OF ATMOSPHERIC PRESSURE PLASMA BY CAPILLARY DIELECTRIC COVERED ELECTRODE AND ITS APPLICATION TO PHOTORESIST ETCHING AND SURFACE CLEANING

In this study, capillary dielectric covered dielectric barrier discharge was used to generate the atmospheric plasmas and the effect of various gas combinations such as He+0₂, (He+O₂)/Ar, and (He+O₂)/SF₆ on the photoresist etch rate and the change of contact angle were studied. By adding a small percent of O₂ (40sccm) to He(4000sccm), the maximum photoresist etch rate of 170nm/min could be obtained using 400Watts of AC power and the highest photoresist etch rate of 210nm/min could be obtained by adding 20sccm of Ar to the optimized He(4000sccm)/O₂(40sccm). The addition of SF₆ to the optimized He/O₂ did not show any improvement in photoresist etching, instead, when SF₆ was added more than 40sccm, deposition instead of etching has occurred. The contact angle of the glass surface was decreased from 30° to 10°~ 14° after the cleaning with those He/O₂ based plasmas for 0.5 minutes and the lowest contact angle of 10° could be obtained with (4000sccm He + 40sccm O₂)/Ar(20sccm) possibly due to the highest photoresist etch rate. The exposure of He/O₂ based plasma to photoresist surface also decreased the contact angle and X-ray photoelectron spectroscopy data showed that the decrease of contact angle was related to the increase of oxygen content on the surface.