Search

CN-122003644-A - Method for determining sampling scheme and related measuring method

CN122003644ACN 122003644 ACN122003644 ACN 122003644ACN-122003644-A

Abstract

A method of determining a sampling plan for measuring at least one substrate or a portion thereof is disclosed, the substrate being subjected to a lithographic process to expose structures on the substrate using a lithographic apparatus comprising a measurement station for measuring the substrate and an exposure station for exposing the substrate. The method includes determining a correlation between a measurement action at the measurement station and an exposed portion of the at least one substrate, determining an expected variability of a parameter of interest associated with the lithographic process based on the correlation, and determining a sampling plan based on the expected variability.

Inventors

  • J - Salem
  • DING JINGQIAN
  • M. Hauptman
  • R. Walkman

Assignees

  • ASML荷兰有限公司

Dates

Publication Date
20260508
Application Date
20240911
Priority Date
20231011

Claims (15)

  1. 1. A method of determining a sampling plan for measuring at least one substrate or portion thereof, the substrate undergoing a lithographic process to expose structures on the substrate using a lithographic apparatus comprising a measurement station for measuring the substrate and an exposure station for exposing the substrate, the method comprising: Determining a correlation between a measurement action on the measurement station and an exposed portion of the at least one substrate; determining an expected variability of a parameter of interest associated with the lithographic process based on the correlation, and The sampling plan is determined based on the expected variability.
  2. 2. The method of claim 1, wherein the determining the correlation comprises determining which measurement actions the measurement station performs during exposure of each exposed portion of the at least one substrate by the exposure station.
  3. 3. The method of claim 1, wherein the determining a correlation comprises comparing timing data from the measurement station and the exposure station of the lithographic apparatus.
  4. 4. The method of claim 1, wherein a sample density of the sampling plan of a substrate or portion thereof is dependent on the expected variability.
  5. 5. The method of claim 1, wherein the sample density of the sampling plan is increased to increase expected variability.
  6. 6. The method of claim 1, further comprising, for a desired parameter model of interest, an expected parameter variation of interest for each region, and a budget for a total number of parameter measurements for each wafer: Determining uncertainty metrics for various sampling schemes, and The sampling scheme is determined as the sampling scheme that minimizes the uncertainty metric.
  7. 7. The method of claim 6, wherein the uncertainty measure is a normalized model uncertainty.
  8. 8. The method of claim 1, wherein the determining an expected variability comprises determining the expected variability with reference to historical variability data and/or calibration variability data associated with the lithographic process.
  9. 9. The method of claim 1, wherein the determining an expected variability comprises determining the expected variability based on a known motion associated with each measurement action.
  10. 10. The method of claim 1, wherein the parameter of interest is overlay.
  11. 11. The method of claim 1, comprising assessing whether the expected variability is representative or outliers, and excluding any metrology data related to substrates and/or portions thereof assessed as outliers for feedback control of the lithographic process.
  12. 12. The method of claim 11, wherein the excluding metrology data comprises not measuring substrates and/or portions thereof assessed as outliers.
  13. 13. The method of claim 11, wherein the excluding metrology data includes designating the substrate and/or portion thereof assessed as abnormal values for monitoring only, such that the substrate or portion thereof is measured, but the resulting metrology data is not used for the feedback control of the lithographic process.
  14. 14. The method of claim 13, wherein the resulting metrology data is evaluated to determine if the substrate requires rework.
  15. 15. A computer program comprising program instructions operable, when run on a suitable device, to perform the method of any one of claims 1 to 6.

Description

Method for determining sampling scheme and related measuring method Cross Reference to Related Applications The present application claims priority from EP application 23203062.7 filed on 10/11 of 2023, which is incorporated herein by reference in its entirety. Technical Field The present invention relates to a control apparatus and a control method, which can be used, for example, to maintain performance in device manufacturing by a patterning process such as photolithography. The invention also relates to a method of manufacturing a device using lithographic techniques. The invention also relates to a computer program product for implementing such a method. Background A lithographic process is a process in which a lithographic apparatus applies a desired pattern onto a substrate, typically onto a target portion of the substrate, and thereafter various processing chemical and/or physical processing steps create functional features of a complex product by patterning. Precise placement of patterns on a substrate is a major challenge in reducing the size of circuit components and other products that can be produced by photolithography. In particular, the challenge of accurately measuring features on already placed substrates is the key step of being able to stack successive feature layers with sufficient accuracy to produce a working device with high yield (yield). In general, in today's submicron semiconductor devices, so-called overlay should be realized within tens of nanometers, which can be as low as a few nanometers in the most critical layers. Thus, modern lithographic apparatus involve a large number of measurement or "mapping" operations prior to the step of actually exposing or otherwise patterning the substrate at the target location. So-called advanced alignment models have been and will continue to be developed to more accurately model and correct nonlinear distortions of the wafer 'grid' caused by the processing steps and/or the lithographic apparatus itself. Alignment is typically measured using an alignment sensor within the lithographic apparatus. The alignment sensor measures position information (alignment data) of the periodic structure or the alignment mark so that the alignment model can conform to the alignment data. Alignment metrology can be applied sequentially to the exposure (e.g., where the lithographic apparatus has only one stage for (alignment) measurement and exposure), or at least partially simultaneously to the exposure (e.g., where the lithographic apparatus has separate measurement and exposure stages). It is also known to use a separate alignment station for alignment measurement. Such independent alignment measurements may be performed online (e.g., prior to each wafer exposure) and/or offline (e.g., on a subset of the exposed wafers). In such lithographic processes, as well as other manufacturing processes, measurements of the created structure are often required, for example for process control and verification. Various tools for making such measurements are known, including scanning electron microscopes, which are commonly used to measure Critical Dimensions (CD), and specialized tools for measuring overlay, i.e., the accuracy of alignment of two layers in a device. Recently, various forms of scatterometers have been developed for use in the lithographic arts. The fabrication process may be, for example, photolithography, etching, deposition, chemical mechanical planarization, oxidation, ion implantation, diffusion, or a combination of two or more thereof. Examples of known scatterometers typically rely on providing a dedicated metrology target. For example, one approach may require a target in the form of a simple grating that is large enough that the measuring beam generates a spot that is smaller than the grating (i.e., the grating is not completely filled). In the so-called reconstruction method, the characteristics of the grating can be calculated by simulating the interaction of the scattered radiation with a mathematical model of the target structure. Parameters of the model are adjusted until the simulated interactions produce a diffraction pattern similar to that observed from a real target. In addition to measuring feature shapes by reconstruction, diffraction-based overlay can also be measured using such a device, as described in published patent application US2006066855 A1. Diffraction-based overlay metrology using dark field imaging of diffraction orders can make overlay measurements on smaller targets. These targets may be smaller than the irradiation point and may be surrounded by product structures on the wafer. Examples of dark field imaging metrology can be found in many published patent applications, for example US2011102753A1 and US20120044470a. Multiple gratings can be measured in one image using a composite grating target. Known scatterometers tend to use light in the visible or near Infrared (IR) bands, which requires that the pitch of the grati