Extreme ultraviolet (EUV) reticle incorporated with a pellicle has been widely used for worldwide EUV mask cores. The EUV reticle is typically stored in an EUV inner pod (EIP), in which the EUV pellicle is served to prevent particle contamination. The pellicle is easily deformed due to its structural weakness, thereby altering its transmission as well as impacting the yield of EUV fabrication. Since the mechanical stress induced by external forces in the EUV pellicle is compressively studied, the exploration of stress altered by the air flow through the pellicle frame and/or the inner topography of the EIP is relatively less studied. Here, we present a numerical simulation approach to elucidate the above issue. The derived pressure acting on the pellicle was significantly modulated by the flow conductance of pellicle frame. A air permeability of 90% lead the induced pellicle stress relatively less than the 10% permeability. It suggested that a higher air permeability of pellicle frame could stabilize the air flow between the inside and outside air domains of pellicle more than that using a lower air permeability. We further compared the pellicle stresses derived from the experiment and calculation during the pumping event (from atmosphere pressure to 5 Pa). Results showed a good agreement between the two models. Together, our study indicates that the mechanical stress with air flow through the pellicle frame may dominate the deflection of EUV pellicle in vacuum and the relevant improvement should be considered accordingly.
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