Grid refinement method

A method of lithographically exposing a substrate, the method comprising:

• receiving, at a pattern generator, pixel values for a first pixel row and a second pixel row, wherein the second pixel row is offset from the first pixel row in a first direction by an amount less than a pixel width;
• exposing a portion of the substrate by scanning a beam across the portion during a first pass, wherein the intensity of the beam varies according to the pixel values of the first pixel row;
• and
• exposing the portion of the substrate by scanning the beam across the portion during a second pass, wherein the intensity of the beam varies according to the pixel values of the second pixel row.

A method for a lithographic process, the method comprising:

• receiving a circuit pattern to be formed on a substrate by a pattern generator,
• determining pixel values for a first pixel row and a second row of the pattern generator such that a collective exposure dose that includes a dose from the first pixel row and a dose from the second pixel row satisfies an exposure dose specified by the circuit pattern;
• exposing the substrate according to the first pixel row;
• and
• exposing the substrate according to the second pixel row using a time delay such that the second pixel row is offset from the first pixel row by an amount less than a pixel size in a first direction and such that a portion of the substrate is exposed according to each of the first pixel row and the second pixel row.