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

Claim 14:
15. 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 at least one of a fitted curve or a look-up table that 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 effect of the one or more calibration pixels comprises determining the change in the birefringence of the substrate as a function of a power of a laser beam of a laser system used for introducing the one or more calibration pixels into the substrate of the photolithographic mask, wherein the laser system has a wavelength that 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;
determining at least one of the fitted curve or the look-up table having information about a relationship between the change in the birefringence of the substrate and the power of the laser beam of the laser system used for introducing the one or more pixels into the substrate of the photolithographic mask; and
controlling the at least one laser beam parameter of the laser system based on the at least one of the fitted curve or the look-up table having information about the relationship between the change in the birefringence and the power of the laser beam of the laser system when writing one or more pixels into the substrate of the photolithographic mask in order to correct the one or more errors of the photolithographic mask.