Positioning device in gantry type of construction having a position-measurement device for measuring the position of a carriage relative to a cross-member

1. A positioning device in a gantry type of construction, comprising:

a base;

a first cross member;

a second cross member;

two linear guides arranged parallel to each other on the base and supporting the first cross member and the second cross member in a manner allowing movement in a first direction;

a carriage having a functional element supported on the first cross member in a manner allowing movement in a second direction; and

a position-measurement device adapted to detect a position of the carriage relative to the second cross member, the position-measurement device disposed on the carriage and on the second cross member, and including a plurality of scales provided on the second cross member, and scanning heads provided on the carriage and adapted to scan the scales.

2. The positioning device according to claim 1 , wherein the position-measurement device is adapted to determine a spatial position of the carriage relative to the second cross member in all six degrees of freedom.

3. The positioning device according to claim 1 , wherein at least one of the scales on the second cross member includes a 1Dplus scale having a measuring track and a straightness track, scanning heads of the carriage being aligned with the measuring track and the straightness track to read position values in two directions that are linearly independent of each other.

4. The positioning device according to claim 1 , wherein the base is actively vibrationally-damped.

5. The positioning device according to claim 1 , further comprising a position-measurement system adapted to detect a position of the second cross member relative to an absolute reference system, so that the second cross member is used as a movable reference system to determine a spatial position of the carriage relative to the absolute reference system.

6. The positioning device according to claim 5 , wherein the position-measurement system includes at least one 1Dplus scale having a measuring track and a straightness track.

7. The positioning device according to claim 1 , further comprising fine-positioning drives between the carriage and the functional element adapted to permit a correction of a spatial position of the functional element at least in the following degrees of freedom: linear shift in a direction perpendicular to the first and second directions, rotation about the first direction, and rotation about the second direction.

8. The positioning device according to claim 7 , wherein the drives are controllable to adjust for incorrect positions of the carriage.

9. The positioning device according to claim 1 , wherein the functional element includes a table adapted to carry a wafer for processing and/or inspection by a tool mounted above the positioning device.