Patent ID: 7161657

Claim:
A lithographic apparatus comprising: an illumination system configured to condition a beam of radiation; a patterning device holder configured to hold a patterning device, the patterning device serving to impart the beam of radiation with a pattern in its cross-section; a substrate holder configured to hold a substrate; a projection system configured to project the patterned beam of radiation onto a target portion of the substrate; and a positioning device configured to position at least one of said holders, said positioning device comprising: a first drive unit comprising a first part and a second part, the first part being connected to the holder to be positioned, said first part movable relative to the second part; and a second drive unit configured to displace said first drive unit in at least one direction, the second part of the first drive unit being connected to said second drive unit, wherein the second drive unit and the second part of the first drive unit are separated from the first part of the first drive unit by a wall.