Bearing arrangement for reaction mass in a controlled environment

A scanning apparatus used for lithographic processing within a controlled environment, comprising:

• lithographic exposure means;
• a baseframe;
• at least one counter balance movably coupled to said baseframe by at least three first bearings;
• a stage, coupled to said at least one counter balance by at least two second bearings and at least one drive;
• an enclosure, having a controlled environment and enclosing said lithographic exposure means, said stage, said at least two second bearings, said at least one drive, and said at least one counter balance;
• and
• a plurality of bellows, each bellows surrounding a corresponding one of said at least three first bearings and separating said corresponding first bearing from said controlled environment, and each bellows having a first end coupled to one of said at least one counter balance and a second end coupled to said enclosure.

A scanning apparatus used for lithographic processing within a controlled environment, comprising:

• lithographic exposure means;
• a baseframe;
• a stage;
• means for counter balancing movement of said stage;
• first coupling means for movably coupling said counter balancing means to said baseframe;
• second coupling means for movably coupling said stage to said counter balancing means;
• means for driving said stage;
• means for enclosing a controlled environment containing said lithographic exposure means, said stage, said second coupling means, said driving means, and said counter balancing means;
• and
• means for separating said first coupling means from said controlled environment, wherein a volume containing said first coupling means has a pressure independent of a volume containing said controlled environment.