Contamination study on EUV exposure tools using SAGA Light Source (SAGA-LS)

Dedicate beam line for R&D on contamination of EUV exposure tools (BL18) was constructed at Saga Light Source (SAGA-LS) and its operation has been started. BL18 has an advantage of long time exposure, which gives accurate data compared with high-EUV-intensity and short-time experiments using an undulator beam line at New SUBARU synchrotron facility. Carbon contamination growth under low irradiance EUV radiation with fluorocarbon gas injection was examined using Mo/Si multilayer mirror samples. In the EUV intensity region from 11 W/cm 2 to 0.01 W/cm 2 , degradation rate of reflectivity did not depend on the EUV intensity. The degradation rate was proportional to the EUV intensity in the range of less than 0.01 W/cm 2 . Carbon contamination due to resist outgas during EUV exposure was also investigated.