Thermal analysis of extreme ultraviolet pellicle with metallic coatings

- The high exposure EUV heat can decrease the lifetime of the pellicle.
- The emissivity of the Ru coating is depending on the thickness.
- The temperature is dropped when the Ru coating thickness is increased.

In extreme ultraviolet lithography (EUVL), using the pellicle is one of the solution that can mitigate the defects on the mask focal plane. However, the high absorption at the EUV wavelength region leads to thermal damage at the pellicle. The increased thermal temperature could be lowered by the coating layer with high emissivity material. We analyzed the thermal temperature of the EUV pellicle by finite element method and compared with experimental Ru coating data. Thermal stress of the multi-stack pellicle is also calculated and the stress follows the peak thermal temperature change with coating layer thickness.

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