Lithographic Apparatus and Method for Illumination Uniformity Correction and Uniformity Drift Compensation

A device manufacturing method comprising:

• focusing a beam of radiation at a first plane so as to form a substantially constant pupil at the first plane;
• adjusting intensity of the beam of radiation at the first plane by moving fingers located in the first plane into and out of a path of the beam of radiation, wherein a width of a tip of each of the fingers is half that of corresponding actuating devices used to move each corresponding one of the fingers;
• directing the beam of radiation beam onto a patterning device to pattern the beam of radiation;
• and
• projecting the patterned radiation beam onto a substrate.

A method comprising:

• providing fingers located at a first plane, the first plane receiving a substantially constant pupil when illuminated with a beam of radiation;
• and
• providing actuating devices coupled to corresponding ones of the fingers that adjusts an intensity of the beam of radiation at the first plane by moving the fingers located at the first plane into and out of a path of the beam of radiation;
• wherein a width of a tip of each of the fingers is half a width of corresponding ones of the actuating devices used to move each of the corresponding one s of the fingers.