Switching type dual wafer stage

A dual stage assembly, comprising:

• a base;
• a plurality of interferometers mounted on said base for determination of stage positions, said interferometers each including at least one interferometer axis directed towards a moveable mirror;
• a first stage moveable in a plane between multiple positions on said base and having at least a first moveable mirror mounted thereon;
• and
• a second stage moveable in said plane between multiple positions on said base and having at least a second moveable mirror mounted thereon, said first and second stages being moveable to positions wherein the first stage eclipses the second stage with respect to said at least one said interferometer;
• wherein said first and second moveable mirrors are configured to reflect to a common subset of interferometer axes, said second moveable mirror having a reflecting surface that cooperates with said interferometers in said eclipsing positions such that the position of said second stage is continuously determinable.

A dual wafer stage assembly, comprising:

• a base;
• a first stage movable in a plane on said base;
• a second stage movable in said plane on said base;
• and
• a plurality of interferometers mounted along one side of said base which are directed to a first moveable minor mounted on said first stage and a second moveable minor mounted on said second stage where said plurality of interferometers and moveable mirrors cooperate to continuously determine the position of both said stages such that if said first stage is interposed between second said stage and at least one of said interferometers said second stage position is determined by at least one other of said interferometers.

A dual wafer stage assembly, comprising:

• a base;
• a first stage movable in a plane on said base;
• a second stage movable in said plane on said base wherein said second stage is larger than said first stage in at least one dimension of said plane;
• and
• a plurality of interferometers and moveable mirrors wherein said interferometers are mounted on said base and said moveable mirrors are mounted on said first and said second stages and said interferometers and said moveable mirrors are configured to facilitate the continuous determination of the positions of said stages, and where one or more portions of said moveable mirrors mounted on said second stage are located on said second stage where said second stage is larger than said first stage.

A method of utilizing a dual stage assembly where stage position is determined using interferometers, the method comprising:

• sizing a first stage and a second stage based on a determined size and exposure apparatus parameters;
• providing a plurality of interferometers directed in parallel at said stages and dispersed along one side of an area in which said stages will travel such that each of said stages' positions intersect an axis created by at least one of said plurality of interferometers at all times during the movement of said stages;
• equipping said first stage with a first movable mirror dimensioned to allow said interferometers to determine said first stage's position in a first desired direction;
• equipping said second stage with a second movable mirror dimensioned to allow at least one of said plurality of interferometers to determine said second stage's position in said first desired direction even if said first stage should be positioned between said second stage and said dispersed interferometers;
• moving said first and said second stages in said area;
• and
• determining said first stage's position and said second stage's position in said first direction using at least one of said plurality of interferometers for each of said stages' positions at all times.

An exposure apparatus that forms an image on a substrate, comprising:

• a base;
• a first operation area comprising a first optical device that performs a first operation on a first substrate;
• a second operation area being adjacent to the first operational area, the second operational area comprising a second optical device that performs a second operation on a second substrate, the second substrate having previously had the first operation performed on the second substrate in the first operation area;
• a stage system comprising a first stage and a second stage, the first and the second stages holding one of the first substrate and the second substrate and being movable on the base between the first operation area and the second operation area, respectively;
• and
• an interferometer system including a plurality of interferometers, the interferometer system constantly monitoring the position of the each of the first stage and the second stage at all times during the movement of the each stage from the second operation area to the first operation area
• wherein each stage that moves from the second operation area to the first operation area holds the second substrate that has had the second operation performed thereon in the second operation area.