Characteristics of He/O-2 atmospheric pressure glow discharge and its dry etching properties of organic materials

In this study, the characteristics of atmospheric low temperature plasmas g enerated by capillary electrodes with capillary dielectrics were investigat ed for the application of microelectronic cleaning processes. The character istics of the plasmas were studied as a function of capillary aspect ratios , input power, electrode distance. He/O-2 gas flow rate, etc., using a high voltage probe, current probe, and optical emission spectroscopy (OES). The voltage between the electrodes increased with the increase of input power, the increase of electrode distance, the decrease of He flow rate, and the increase of O-2 flow rate. The increase of the voltage has led to unstable filamentary discharge from the stable capillary discharge. The use of elect rodes with capillary dielectrics instead of a conventional dielectric barri er electrode (the electrode covered with non-capillary dielectric) not only decreased the electrode voltage, therefore, increased the stability of the plasma but also increased the discharge current and, therefore, the intens ity of the plasma. Increased ionization and dissociation of the plasma spec ies could be observed by OES with the increase of input power in He/O-2 mix tures. However, with the increase of O-2 flow rate in a constant He flow ra te, the emission peaks from He decreased due to the increased electron cons umption by oxygen while the emission peaks from O-2(+) and O increased due to the increased ionization and dissociation rates with the increase of oxy gen concentration in the He/O-2 gas mixtures. Also, using a He/O-2 gas mixt ure, organic materials such as photoresist could be successfully removed wi th the average etch rates higher than 200 nm/min. (C) 2001 Elsevier Science BN All rights reserved.