Calibration method, inspection method and apparatus, lithographic apparatus, and lithographic processing cell

摘要

Disclosed are methods, apparatuses, and lithographic systems for calibrating an inspection apparatus. Radiation is projected onto a pattern in a target position of a substrate. By making a plurality of measurements of the pattern and comparing the measured first or higher diffraction orders of radiation reflected from the pattern of different measurements, a residual error indicative of the error in a scatterometer may be calculated. This error is an error in measurements of substrate parameters caused by irregularities of the scatterometer. The residual error may manifest itself as an asymmetry in the diffraction spectra.

主权项

1. A method comprising:
measuring at least two measurements of a patterned target on a substrate, wherein the substrate defines an x-y plane and at least one of the at least two measurements is made using an inspection apparatus, and each measurement comprises:
projecting a beam of radiation onto the patterned target, andmeasuring at least one diffraction order of radiation reflected from the patterned target,wherein the at least two measurements are made at two different rotation orientations of the patterned target; determining a first preliminary value of a parameter of the patterned target from the at least one of the at least two measurements; determining a second preliminary value of the parameter of the patterned target from the other one of the at least two measurements, wherein the first and second preliminary values comprise components in the x- and y-direction; and determining a residual error indicative of an error of the inspection apparatus including comparing the at least two measurements, wherein the residual error is a variation in intensity of the at least one diffraction order of radiation reflected from the patterned target caused by the error in the inspection apparatus, wherein the determining comprises using the x- and y-components from the first and second preliminary values of the parameter to calculate the residual error.