Effect of plasma cleanings on the characteristics of MgO layer for plasma display panel

In this study, the effects of plasma cleanings on the outgassing and surface characteristics of a MgO layer used for plasma display panel were investigated. As the plasma cleaning methods, an atmospheric pressure cleaning with He/O2/Ar/N2 and a low pressure inductively coupled plasma (ICP) cleaning with Ar/O2 were used. When the outgassing characteristics of the MgO layer cleaned by the plasmas were measured in a vacuum from room temperature to 673 K by a quadrupole mass spectrometer, a decrease in vapor pressures from the outgassing species such as H2O, CO2, CO and H2 could be observed due to the removal of the contamination such as H2O and organic materials from the MgO surface by the plasma cleanings. The MgO layer after the atmospheric pressure plasma cleaning showed lower outgassing compared to that after the low pressure ICP cleaning, however, the surface roughness of the MgO after the cleanings was lower for the low pressure ICP cleaning. Secondary electron emission coefficient (SEEC) of the MgO layers was increased approximately 1.5–2.5 times after the plasma cleanings for both the atmospheric pressure plasma cleaning with He/O2/Ar/N2 and the low pressure plasma cleaning with Ar/O2.