Lithographic apparatus and device manufacturing method

A method for configuring an illumination source of a lithographic apparatus, the method comprising:

• dividing the illumination source into pixel groups, each pixel group including one or more illumination source points;
• selecting an illumination shape to expose a pattern;
• calculating a plurality of responses for a plurality of changes in the illumination shape, each of the plurality of changes effected by a change of state of a pixel group;
• and
• adjusting the illumination shape based on the plurality of responses.

A computer product having machine executable instructions, the instructions being executable by a machine to perform a method for configuring an illumination source of a lithographic apparatus, the method comprising:

• dividing the illumination source into pixel groups, each pixel group including one or more illumination source points;
• selecting an illumination shape to expose a pattern, the illumination shape formed with at least one pixel group;
• iteratively calculating a lithographic metric as a result of a change of state of a pixel group in the illumination source, the change of the state of the pixel group creating a modified illumination shape;
• and
• adjusting the illumination shape based on the iterative results of calculations.

A lithographic apparatus comprising:

• an illumination system configured to condition a beam of radiation;
• a substrate table configured to hold a substrate;
• a projection system configured to project a beam of radiation patterned by a patterning device onto a surface of the substrate;
• and
• a processor configured to perform a method for configuring an illumination source of a lithographic apparatus, the method comprising
• dividing the illumination source into pixel groups, each pixel group including one or more illumination source points;
• selecting an illumination shape to expose a pattern, the illumination shape formed with at least one pixel group;
• iteratively calculating a lithographic metric as a result of a change of state of a pixel group in the illumination source, the change of the state of the pixel group creating a modified illumination shape;
• and
• adjusting the illumination shape based on the iterative results of calculations.