Patent ID: 7006208

Claim:
A method for dynamic pre-compensation of focus and tilt, comprising: estimating the error correction over a full wafer surface, including all scan fields, the estimating including exposing a grating reticle with predetermined tilt and defocus in order to provide a numeric readout of focus and tilt variation in all individual fields, exposing the grating using the real product file of the particular layer being illuminated, reading-out the test pattern for a single standard test wafer and track sequence with the dose changed in the product file, estimating defocus using the formula ΔZ=ΔX*θ, where ΔZ is estimated defocus, ΔX is deviation of a printed band from its expected position (left edge, right edge, or centerline), and θ being the user-controlled tilt, obtaining the deviation of data and comparing the printed bands' with baseline expected positions, and compiling a focus compensation table by measuring the focus deviations at two bands per field, enabling equal but opposite defocus to be incorporated at the time of exposure; applying the correction over the same wafer surfaces; and obtaining the read-out of the focus error and its compensation made on the congruent domains.