Reversed, double-helical bellows seal

A lithography system comprising:

• a reticle stage contained within a first chamber;
• an illumination source;
• an optical device contained within a second chamber;
• a wafer stage contained within a third chamber;
• a first reverse double bellows seal which includes,
• a plurality of rings including first and second end rings and a first middle ring, the first end ring being connected to the first chamber, and the second end ring being connected to the second chamber;
• a first bellows formed from a flexible material, the first bellows being sealingly connected between the first end ring and the first middle ring, the first bellows having a twist bias in a first rotational direction relative to an axis of the rings;
• and
• a second bellows formed from a flexible material, the second bellows being sealingly connected between the second end ring and the first middle ring, the second bellows having a twist bias in a second rotational direction relative to an axis of the rings that is opposite that of the first rotational direction;
• and
• a second reverse double bellows seal which includes,
• a plurality of rings including third and fourth end rings and a second middle ring, the third end ring being connected to the second chamber, and the fourth end ring being connected to the third chamber;
• a third bellows formed from a flexible material, the third bellows being sealingly connected between the third end ring and the second middle ring, the third bellows having a twist bias in a third rotational direction relative to an axis of the rings;
• and
• a fourth bellows formed from a flexible material, the fourth bellows being sealingly connected between the fourth end ring and the second middle ring, the fourth bellows having a twist bias in a fourth rotational direction relative to an axis of the rings that is opposite that of the third rotational direction.