Atmospheric Pressure Plasma Ashing for Display Manufacturing

Abstract

Due to the various advantages of the use of atmospheric pressure, recent studies on the ashing of organic materials are focused on the atmospheric pressure plasma rather than low pressure plasma. In this study, atmospheric pressure plasma was generated using dielectric covered electrodes and AC pulsed power supply (10 kV) driven at low frequency to remove organic materials on the surfaces of metal such as Cr. In such a configuration, the effects of process conditions and ashing gases on the ashing properties have been investigated. Nitrogen (N2) and oxygen (O2) were used for ignition and ashing, respectively. By adding small amount of O2 to N2, the photoresist ashing rate was increased due to the increment of oxygen radicals in the plasma. However, further addition of oxygen decreased the photoresist ashing rate, possibly because of the lower plasma density caused by the formation of negative ions between oxygen molecules and electrons in the plasma. Additionally, the effect of input voltage on ashing was investigated. The raised input voltage increased the ashing effect possibly due to the increased chemical reaction with organic materials resulting in the increased volatilization and detachment from the surface. In this paper, optimal process condition for gas flow rate and process gap will be discussed.