Lithographic apparatus with adjusted exposure slit shape enabling reduction of focus errors due to substrate topology and device manufacturing method

A device manufacturing method comprising:

• conditioning a radiation beam;
• imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam;
• projecting the patterned radiation beam in a scanning exposure along a scanning direction onto a target portion of a substrate;
• and
• forming a slit shaped image, the slit shaped image having a length in the scanning direction and a width substantially perpendicular to the scanning direction, the slit shaped image having a curved shape with a slit curvature in the scanning direction, the slit shaped image formed to create a curved pattern image portion of the patterned radiation beam in an image plane of the projection system.

A computer program on a computer-readable medium to be loaded by a computer, the computer comprising a processor and a memory, the memory being connected to the processor, the computer being interfaced with a lithographic apparatus comprising:

• an illumination system configured to condition a radiation beam;
• a patterning device support configured to support a patterning device, the patterning device capable of imparting the radiation beam with a pattern in its cross-section to form a patterned radiation beam;
• a substrate table constructed to hold a substrate;
• and
• a projection system configured to project the patterned radiation beam in a scanning exposure along a scanning direction onto a target portion of the substrate,
• wherein the illumination system is configured to form in a plane of the patterning device a slit shaped image having a curved shape with a slit curvature in the scanning direction and having a length in the scanning direction and a width substantially perpendicular to the scanning direction;
• wherein the computer is arranged as a control system to control at least the illumination system;
• and
• wherein the computer program, after being loaded, is adapted to allow the processor to control the illumination system to:
• form the slit shaped image, and
• arrange the slit shaped image to create a curved pattern image portion of the patterned radiation beam in an image plane of the projection system.

A lithographic apparatus comprising:

• a patterning device support configured to support a patterning device, the patterning device capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam;
• a substrate table constructed to hold a substrate;
• a projection system configured to project the patterned radiation beam in a scanning exposure along a scanning direction onto a target portion of the substrate;
• and
• an illumination system configured to form in a plane of the patterning device an exposure slit to illuminate the patterning device, the exposure slit having a curved shape with a slit curvature in the scanning direction and a length in the scanning direction and a width substantially perpendicular to the scanning direction.