Prediction of ultraviolet-induced damage during plasma processes in dielectric films using on-wafer monitoring techniques

We measured electron-hole pairs generated in dielectric film using our developed on-wafer monitoring technique to detect electrical currents in the film during the plasma etching processes. The electron-hole pairs were generated by plasma induced ultraviolet (UV) photons, and the number of electron-hole pairs depends on the UV wavelength. In SiO2 film, UV light, which has a wavelength of less than 140nm, generates electron-hole pairs, because the band gap energy of the film is 8.8eV. On the other hand, in Si3N4 film, which has a band gap energy level of 5.0eV, UV light below 250nm induces the electron-hole pairs. Additionally, we evaluated the fluorocarbon gas plasma process that induces UV radiation damage using multilayer sensors that consisted of both SiO2 and Si3N4 stacked films. In these cases, electron-hole pair generation depended on the dielectric film structure. There were more electron-hole pairs generated in the SiO2 deposited on the Si3N4 film than in the Si3N4 deposited on the SiO2 film. As a...