An auto-focusing system is disclosed. The system includes an illumination source. The system includes an aperture. The system includes a projection mask. The system includes a detector assembly. The system includes a relay system, the relay system being configured to optically couple illumination transmitted through the projection mask to an imaging system. The relay system also being configured to project one or more patterns from the projection mask onto a specimen and transmit an image of the projection mask from the specimen to the detector assembly. The system includes a controller including one or more processors configured to execute a set of program instructions. The program instructions being configured to cause the one or more processors to: receive one or more images of the projection mask from the detector assembly and determine quality of the one or more images of the projection mask.

A method for clustering based on unsupervised learning according to an embodiment of the invention enables clustering for newly generated patterns and is robust against noise, and does not require tagging for training data. According to one or more embodiments of the invention, noise is accurately removed using three-dimensional stacked spatial auto-correlation, and multivariate spatial probability distribution values and polar coordinate system spatial probability distribution values are used as learning features for clustering model generation, making them robust to noise, rotation, and fine unusual shapes. In addition, clusters resulting from clustering are classified into multi-level clusters, and stochastic automatic evaluation of normal/defect clusters is possible only with measurement data without a label.

Methods and systems for determining one or more characteristics of light in an optical system are provided. One system includes first detector(s) configured to detect light having one or more wavelengths shorter than 190 nm emitted from a light source at one or more first angles mutually exclusive of one or more second angles at which the light is collected from the light source by an optical system for illumination of a specimen and to generate first output responsive to the light detected by the first detector(s). In addition, the system includes a control subsystem configured for determining one or more characteristics of the light at one or more planes in the optical system based on the first output.

Methods and systems for detecting defects on a mask are provided. One method includes generating a database reference image for a multi-die mask by simulation and detecting first defects on the mask by comparing the database reference image to images of the mask generated by an imaging subsystem for a first of the multiple dies. The method also includes generating a die reference image for the first of the multiple dies by applying one or more parameters of the imaging subsystem learned by generating the database reference image to the images generated by the imaging subsystem of one or more of the multiple dies other than the first multiple die. In addition, the method includes detecting second defects on the mask by comparing the die reference image to the images of the mask generated by the imaging subsystem for the first of the multiple dies.

The present disclosure generally provides for a system and method for measuring one or more characteristics of one or more substrates in a multi-station processing system using one or more metrology modules at a plurality of metrology stations. In one embodiment, a system controller is configured to cause the multi-station processing system to perform a method that includes processing a plurality of substrates at a plurality of processing stations, advancing one or more of the plurality of substrates to a respective metrology station, measuring one or more characteristics of the plurality of substrates at the respective metrology station, determining a processing performance metric based on the one or more characteristics, comparing the processing performance metric to a tolerance limit to determine if an out of tolerance condition has occurred, and adjusting one or more processing parameters when it is determined that an out of tolerance condition has occurred.

A method for evaluating images of a printed pattern. The method includes obtaining a first averaged image of the printed pattern, where the first averaged image is generated by averaging raw images of the printed pattern. The method also includes identifying one or more features of the first averaged image. The method further includes evaluating the first averaged image, using an image quality classification model and based at least on the one or more features. The evaluating includes determining, by the image quality classification model, whether the first averaged image satisfies a metric.

A substrate inspection apparatus includes: a storage configured to store inspection image data obtained from a captured image of a periphery of a substrate on which a plurality of films is formed, and an inspection recipe; and an edge detector configured to detect a target edge as an edge of an inspection target film among the films on the basis of the inspection image data stored in the storage by using the inspection recipe stored in the storage. Each of edges of the films extends along the periphery of the substrate. The inspection recipe is configured by combining parameters each of which has one option specified among a plurality of options.

Described herein is a method of training a model configured to predict whether a feature associated with an imaged substrate will be defective after etching of the imaged substrate and determining etch conditions based on the trained model. The method includes obtaining, via a metrology tool, (i) an after development image of the imaged substrate at a given location, the after development image including a plurality of features, and (ii) an after etch image of the imaged substrate at the given location; and training, using the after development image and the after etch image, the model configured to determine defectiveness of a given feature of the plurality of features in the after development image. In an embodiment, the determining of defectiveness is based on comparing the given feature in the after development image with a corresponding etch feature in the after etch image.

A method for in-situ wave front detection within an inspection system is disclosed. The method includes generating light with a light source and directing the light to a stage-level reflective mask grating structure disposed on a mask stage. The method includes directing light reflected from the stage-level reflective structure to a detector-level mask structure disposed in a plane of a detector and then collecting, with an optical element, light reflected from the detector-level mask structure. The method includes forming a pupil image on the detector and laterally shifting the stage-level reflective mask, with the mask stage, across a grating period of the stage-level reflective mask grating structure to provide phase reconstruction for lateral shearing interferometry. The method includes selectively impinging light reflected from the optical element on the one or more sensors of the detector.

A method for in-situ wave front detection within an inspection system is disclosed. The method includes generating light with a light source and directing the light to a stage-level reflective mask grating structure disposed on a mask stage. The method includes directing light reflected from the stage-level reflective structure to a detector-level mask structure disposed in a plane of a detector and then collecting, with an optical element, light reflected from the detector-level mask structure. The method includes forming a pupil image on the detector and laterally shifting the stage-level reflective mask, with the mask stage, across a grating period of the stage-level reflective mask grating structure to provide phase reconstruction for lateral shearing interferometry. The method includes selectively impinging light reflected from the optical element on the one or more sensors of the detector.