Patent ID: 6869739

Claim:
A method of modeling dose and focus response in lithographic imaging to simulate an optical critical dimension (OCD) metrology system comprising: providing a pattern of an object to be lithographically printed on a substrate; using imaging conditions to be employed in a metrology imaging system, creating simulated aerial images of the object pattern to be transferred to a resist film on the substrate at different focus settings of the metrology imaging system; using characteristics of the resist film on the substrate, creating simulated images of the latent image of the object pattern in the resist film on the substrate at different exposure dose and focus settings of the metrology imaging system; optionally, using characteristics of the latent image of the object pattern, creating simulated images of the developed image of the object pattern in the resist film on the substrate at different exposure dose and focus settings of the metrology imaging system; optionally, using characteristics of the developed image of the object pattern, creating simulated images of the etched image of the object pattern in the substrate at different exposure dose and focus settings of the metrology imaging system; converting the simulated images of the latent image, developed image, or etched image of the object pattern at different exposure dose and focus settings to polygons having more than four sides; determining the Fourier spectrum of the polygons simulating the images of the object pattern at different exposure dose and focus settings; using the spectrum of the polygons simulating the images of the object pattern, creating simulated aerial images of the object pattern developed in the resist film, at different dose and focus settings, as viewed by the OCD metrology system; and evaluating critical characteristics of the simulated object pattern viewed by the OCD metrology system.