Patent ID: 11914289
Assignee: CARL ZEISS SMS LTD.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for determining an effect of one or more pixels to be introduced into a substrate of a photolithographic mask for at least partly correcting one or more errors of the photolithographic mask, the photolithographic mask having one or more pattern elements, wherein one or more calibration pixels serve to determine a calibration curve which can be used for controlling a pixel writing which at least partly corrects the one or more errors of the photolithographic mask, the method comprising:
determining the effect of the one or more calibration pixels by determining a change in birefringence of the substrate of the photolithographic mask having the one or more pattern elements, wherein determining the change in the birefringence comprises using a transmissive optical birefringence measurement system using a wavelength which is larger than an actinic wavelength of the photolithographic mask, the actinic wavelength being the wavelength the photolithographic mask is designed for illuminating a photoresist on a wafer;
establishing the calibration curve by using the determined change in birefringence of the substrate; and
controlling the pixel writing process for at least partly correcting the one or more errors of the photolithographic mask based on the calibration curve.