CHARACTERIZATION OF SI3N4 SURFACE AFTER E XCIMER-LASER RADIATION

The effect of excimer laser radiation to silicon nitride ceramic surfa ce morphology was investigated, The response of the surface at irradia tion to different laser fluences and in-vacuo measurements of the part icle emission due to laser irradiation were examined. The irradiated s urface showed pillar-like features at low fluence (20kJ/m(2)), however , hat surfaces were produced at high fluence (100kJ/m(2)). Quadrupole mass spectrometry during laser irradiation showed that the emitted par ticles were Si+, Y+, O and N, It is thought that the surface silicon n itride and/or grain boundary crystal phase (Si3N4 . Y2O3) was decompos ed during laser irradiation, and the resulting Si+ to form SiO2 layers and/or pillars on the surface. These surface features degrated the st rength of the specimens due to pore formation just under the surface.