EP-4741926-A1 - METHOD OF DETERMINING A PERFORMANCE PARAMETER DISTRIBUTION

EP4741926A1EP 4741926 A1EP4741926 A1EP 4741926A1EP-4741926-A1

Abstract

Provided is a method of determining a performance parameter comprising determining a plurality of regions on a substrate; determining a plurality of performance parameter estimation models corresponding to the plurality of regions; determining performance parameter estimation model parameters for the plurality of performance parameter estimation models and applying at least one of the plurality of performance parameter estimation models with the determined model parameters to determine the performance parameter for the corresponding region of the plurality of regions.

Inventors

URBANCZYK, Adam, Jan

Assignees

ASML Netherlands B.V.

Dates

Publication Date: 20260513
Application Date: 20241107

Claims (15)

A method of determining a performance parameter, comprising: determining a plurality of regions on a substrate; determining a plurality of performance parameter estimation models corresponding to the plurality of regions; determining performance parameter estimation model parameters for the plurality of performance parameter estimation models; and applying at least one of the plurality of performance parameter estimation models with the determined model parameters to determine the performance parameter for the corresponding region of the plurality of regions.
The method of claim 1, wherein the plurality of regions and corresponding plurality of performance parameter estimation models are determined based on a previous processing step of the substrate.
The method of any previous claim, wherein the plurality of regions and the corresponding plurality of performance parameter estimation models are determined based on a parameter describing a property of each region of the plurality of regions; wherein the property is location, scale, skewness and/or kurtosis of measurement data corresponding to each region or the plurality of regions.
The method of claim 3, wherein the step of determining the plurality of performance parameter estimation models further comprises: measuring a plurality of measurement locations on the substrate to obtain the measurement data; evaluating a performance parameter estimation model for each of the plurality of measurement locations based on the measurement data so as to obtain the plurality of performance parameter estimation models, wherein the plurality of regions are determined based on the plurality of performance estimation models; and applying spatial filtering to remove noise in the plurality of performance estimation models across the substrate.
The method of any previous claim, wherein the model parameters of the plurality of performance parameter estimation models are determined by hyperparameter fitting for each one of the parameters comprised in each performance parameter estimation model.
The method of any previous claim, further comprising configuring a property of a measurement apparatus based on the determined plurality of regions, wherein the property of the measurement apparatus is a field of view and/or a sampling scheme.
The method of any previous claim, wherein the performance parameter is edge placement error, overlay, critical dimension and/or the local statistical distribution of said performance parameters.
The method of any previous claim, wherein each of said plurality of performance estimation models comprises a respective distribution model.
The method of any previous claim, wherein model parameters comprise one or more of location, scale, skew and/or kurtosis.
The method of any previous claim, wherein the plurality of performance estimation models comprise a model family, wherein the higher order distributions in the model family can be reduced to lower order distributions by setting one or more of the model parameters to a neutral value; and wherein the method further comprises evaluating the family of models for each of the plurality of locations based on an evaluation criterion, wherein said evaluation criterion determines an estimation accuracy metric.
A non-transient computer program carrier comprising program instructions operable to perform the method of any preceding claim, when run on a suitable apparatus.
A processing arrangement comprising: the non-transient computer program carrier of claim 11; and a processor operable to run the computer program comprised on said non-transient computer program carrier.
A metrology apparatus comprising the processing arrangement of claim 12.
The metrology apparatus of claim 13, operable to measure the substrate to obtain said measurement data.
The metrology apparatus of claim 13 or 14, wherein the processing arrangement is further operable to determine corrections for controlling a property of said metrology apparatus based on the determined performance parameter, wherein the property of the metrology apparatus is a field of view and/or a sampling scheme.

Description

BACKGROUND Field of the Invention 0001 The present invention relates to a metrology apparatus and methods usable, for example, to perform metrology in the manufacture of devices by lithographic techniques. The invention further relates to such methods for determining a performance parameter in a lithographic process. Background Art 0002 A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., including part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. 0003 In lithographic processes, it is desirable frequently to make measurements of the structures created, e.g., for process control and verification. Various tools for making such measurements are known, including scanning electron microscopes, which are often used to measure critical dimension (CD), and specialized tools to measure overlay, the accuracy of alignment of two layers in a device. Recently, various forms of scatterometers have been developed for use in the lithographic field. These devices direct a beam of radiation onto a target and measure one or more properties of the scattered radiation - e.g., intensity at a single angle of reflection as a function of wavelength; intensity at one or more wavelengths as a function of reflected angle; or polarization as a function of reflected angle - to obtain a diffraction "spectrum" from which a property of interest of the target can be determined. 0004 Examples of known scatterometers include angle-resolved scatterometers of the type described in US2006033921A1 and US2010201963A1. The targets used by such scatterometers are relatively large, e.g., 40µm by 40µm, gratings and the measurement beam generates a spot that is smaller than the grating (i.e., the grating is underfilled). Examples of dark field imaging metrology can be found in international patent applications US20100328655A1 and US2011069292A1 which documents are hereby incorporated by reference in their entirety. Further developments of the technique have been described in published patent publications US20110027704A, US20110043791A, US2011102753A1, US20120044470A, US20120123581A, US20130258310A, US20130271740A and WO2013178422A1. These targets can be smaller than the illumination spot and may be surrounded by product structures on a wafer. Multiple gratings can be measured in one image, using a composite grating target. The contents of all these applications are also incorporated herein by reference. 0005 Today's patterning performance may be characterized by edge placement errors (EPE). The position error of the edge of a feature is determined by the features lateral position error (overlay, pattern shift) and the error in size of the feature (CD error). Part of the feature dimension and position errors is very local and stochastic in nature; e.g., dependent on local placement errors relating to local overlay (LOVL), local CD uniformity (LCDU), Line Edge Roughness (LER) and line width roughness (LWR). All of these may be important contributors to the EPE performance. 0006 Owing to the local and stochastic nature of the EPE metric, measuring EPE is metrology intensive, in particular across a substrate. Thus, modelling is typically used to determine EPE distribution. Currently, only a single distribution model is used to describe EPE distribution across a substrate. It may be desirable to provide improved methods of determining performance parameter distribution across a substrate, e.g., EPE. SUMMARY OF THE INVENTION 0007 The invention in a first aspect provides a method of determining a performance parameter comprising determining a plurality of regions on a substrate; determining a plurality of performance parameter estimation models corresponding to the plurality of regions; determining performance parameter estimation model parameters for the plurality of performance parameter estimation models and applying at least one of the plurality of performance parameter estimation models with the determined model parameters to determine the performance parameter for the corresponding region of the plurality of regions. 0008 In a further embodiments, the invention provides a computer implemented invention comprising the features of the method of the first aspect of the invention. Additionally, the invention provides a computer program comprising program instructions operabl