主权项 |
1. A pellicle comprising a pellicle frame, a pellicle membrane bonded to an upper annular face of said pellicle frame, an air passage penetrating a bar of said pellicle frame for communicating a pellicle closed space with an external atmosphere, and a filter disposed to close at least part of said air passage, wherein at least one of the opening of said air passage that opens in said pellicle closed space and the opening of said air passage that opens outside said pellicle closed space is disposed to look either in an upward direction or in a downward direction; said upward direction being a direction facing a plane which includes said pellicle membrane. |