Abstract: The invention relates to a computer implemented method for providing a fast sub-pixel alignment of an image of an object comprising integrated circuit patterns with a reference image, the method comprising: defining a search space comprising potential displacements between the image of the object and the reference image, wherein the search space depends on a preliminary alignment accuracy and a desired sub-pixel alignment accuracy; aligning the image of the object with the reference image by finding a potential displacement between the image of the object and the reference image within the search space that optimizes an alignment accuracy measure. The invention further relates to a corresponding system.

Abstract: A method for detecting printing defects in a photolithography mask that will print on a wafer when using the photolithography mask in a specific photolithography system to print semiconductor structures on the wafer, the method comprising: acquiring a first aerial image of the photolithography mask using a mask inspection system; generating a second aerial image of the photolithography mask by applying a machine learning model (26) to the first aerial image, wherein the machine learning model is trained to map a first aerial image acquired by a mask inspection system to a second aerial image that emulates the application of the specific photolithography system to the photolithography mask; and detecting printing defects in the photolithography mask by comparing the second aerial image to a reference image.

Abstract: The invention relates to a computer implemented method for generating an aerial image of a model of a photolithography mask under illumination by incident electromagnetic waves, the method comprising: a) Approximately simulating the propagation of the incident electromagnetic waves within a first section of the photolithography mask that comprises multiple structures; b) Simulating the propagation of the simulated electromagnetic waves from step a) within a second section of the photolithography mask analytically or numerically; c) Simulating a representation of an electromagnetic near field of the model of the photolithography mask by propagating the simulated electromagnetic waves from step b) to a near field plane; and d) Generating an aerial image of the photolithography mask.

Abstract: The invention relates to a computer implemented method for simulating an aerial image of a model of a photolithography mask illuminated by incident electromagnetic waves, the method comprising: obtaining the model of the photolithography mask, the model describing the photolithography mask at least partially in a dimension orthogonal to the mask carrier plane; simulating the propagation of the incident electromagnetic waves through the model of the photolithography mask using a machine learning model, wherein the machine learning model maps the model of the photolithography mask to a representation of an electromagnetic field generated by the incident electromagnetic waves on the photolithography mask; obtaining the aerial image of the model of the photolithography mask by applying a simulation of an imaging process. The invention also relates to corresponding computer programs, computer-readable media and systems.

Abstract: The invention relates to a computer implemented method for simulating an aerial image of a model of a photolithography mask illuminated by incident electromagnetic waves, the method comprising: obtaining the model of the photolithography mask; simulating the propagation of the incident electromagnetic waves through the model of the photolithography mask using a machine learning model, wherein the machine learning model maps the model of the photolithography mask to a representation of an electromagnetic field generated by the incident electromagnetic waves on the photolithography mask; obtaining the aerial image of the model of the photolithography mask by applying a simulation of an imaging process. The invention also relates to corresponding computer programs, computer-readable media and systems.

Abstract: A computer implemented method for simulating an aerial image of a design of a photolithography mask comprises: obtaining an illumination angle distribution in the pupil plane of the light source; selecting a number of illumination angles by solving an optimization problem; for each selected illumination angle, simulating an electromagnetic near field; for at least one further illumination angle of the illumination angle distribution in the pupil plane of the light source approximating an electromagnetic near field; and obtaining the simulated aerial image of the design of the photolithography mask by superimposing the intensities obtained by imaging the electromagnetic near fields into a wafer plane. Systems can detect defects or assess the relevance of defects or for aligning aerial images.