Apparatus and method to control vacuum at porous material using multiple porous materials

An immersion liquid confinement apparatus for confining an immersion liquid in an immersion area that includes a gap between a projection system and an object of exposure in an immersion lithography system, the apparatus also recovering the immersion liquid from the immersion area, the apparatus comprising:

• a confinement member that includes an outlet and an aperture through which a patterned image is projected onto the object;
• a first porous member covering the outlet and having a first surface that faces the object and a second surface opposite the first surface, the second surface contacting a first chamber and the immersion liquid being recovered to the first chamber through the first porous member;
• and
• a second porous member having first and second oppositely-facing surfaces, the first surface of the second porous member contacting the first chamber, the second surface of the second porous member contacting a second chamber that is different from the first chamber and the immersion liquid being recovered through the second porous member from the first chamber to the second chamber.

An immersion lithography apparatus comprising:

• a projection system having a final optical element;
• a movable stage that is movable to a position below the projection system such that a gap exists between the final optical element and a surface of the movable stage, an immersion liquid being filled in the gap between the surface and the final optical element;
• and
• a confinement member that maintains the immersion liquid in the gap between the surface and the final optical element, the confinement member including:
• an outlet;
• an aperture through which a patterned image is projected by the projection system through the immersion liquid onto the movable stage;
• a first porous member covering the outlet and having a first surface that faces the surface of the stage and a second surface opposite the first surface, the second surface contacting a first chamber and the immersion liquid being recovered through the first porous member to the first chamber;
• and
• a second porous member disposed adjacent to and spaced from the second surface of the first porous member, the second porous member having a first surface that faces the second surface of the first porous member and a second surface opposite the first surface of the second porous member, the second surface of the second porous member contacting a second chamber that is different from the first chamber and the immersion liquid being recovered through the second porous member from the first chamber to the second chamber.