Effect of contaminants on pellicle lifetime for EUV lithography

The lifetime of the EUV pellicle might be reduced, if contaminant particles accumulate on the pellicle during the EUV lithography process. Through the simulation, the temperature change, deformation, and stress of the pellicle with the type, shape, size, number and location of contaminated particles were examined. And the lifetime expectancy of pellicles for EUV lithography of various structures was compared through a relative comparison of failure points due to thermal deformation. The difference in thermal properties such as heat capacity, thermal conductivity, emissivity, and thermal expansion coefficient of the pellicle and the contaminated particle generated thermal stress in the area where the pellicle and the contaminated particle abutted, and the thermal stress increased as the exposure was repeated. In addition, if exposure continued even after the convergence of temperature, deformation, and thermal stress, physical fatigue due to exposure and cooling could accumulate and shorten the lifetime of the pellicle.