Metrology in the presence of CMOS under array (CUA) structures utilizing an effective medium model with classification of CUA structures

Patent metadata

Field	Value
Publication number	US-12372882-B2
Application number	US-202318217199-A
Country	US
Kind code	B2
Filing date	Jun 30, 2023
Priority date	Jun 30, 2023
Publication date	Jul 29, 2025
Grant date	Jul 29, 2025

Abstract

A system, may include a controller configured to cause the processors to implement a measurement recipe by: receiving optical measurement data for training samples after a first process step for fabricating complementary metal-oxide-semiconductor (CMOS) under array (CuA) devices, wherein the CuA devices include first structures with a non-uniform spatial distribution; classifying the first structures into spatially-continuous regions based on unsupervised clustering; receiving optical measurement data for the training samples after a second process step, wherein the CuA devices after the second process step include periodic second structures above the first structures; developing effective medium models for the first structures; developing measurement models for determining measurements of the CuA devices; receiving optical measurement data for test samples after the second process step; and generating values of the metrology measurements of the second structures based on the optical measurement data for the test samples and the measurement models.

First claim

What is claimed:

1. A system, comprising:
a controller including one or more processors configured to execute program instructions causing the one or more processors to implement a measurement recipe by:
receiving optical measurement data for one or more training samples after a first process step for fabricating complementary metal-oxide-semiconductor (CMOS) under array (CuA) devices, wherein the CuA devices include first structures with a non-uniform spatial distribution after the first process step;
classifying the first structures into spatially-continuous regions based on unsupervised clustering of the optical measurement data for the one or more training samples after the first process step;
receiving optical measurement data for the one or more training samples after a second process step for fabricating the CuA devices, wherein the CuA devices after the second process step include periodic second structures above the first structures;
developing effective medium models for the spatially-continuous regions of the first structures;
developing measurement models for determining one or more measurements of the CuA devices based on the effective medium models for the spatially-continuous regions of the first structures and the optical measurement data for the one or more training samples after the second process step;
receiving optical measurement data for one or more test samples after the second process step for fabricating the CuA devices; and
generating values of the one or more metrology measurements of the second structures on the one or more test samples based on the optical measurement data for the one or more test samples and the measurement models.

2. The system of claim 1 , wherein the first structures include CMOS structures.

3. The system of claim 1 , wherein the first structures include CMOS structures and mold structures, wherein the mold structures include precursors to the second structures.

4. The system of claim 1 , wherein the one or more measurements comprises:
an inspection measurement.

5. The system of claim 4 , wherein the inspection measurement comprises:
at least one of an identification or a classification of a defect in the second structures.

6. The system of claim 1 , wherein the first structures on the one or more test samples have a common spatial distribution as the first structures on the one or more training samples.

7. The system of claim 1 , wherein the first structures on the one or more test samples have a different spatial distribution than the first structures on the one or more training samples.

8. The system of claim 1 , wherein at least one of the effective dispersion models comprise:
at least one of a harmonic oscillator model, a Tauc-Lorentz model, a Cauchy model, a Bruggeman effective medium approximation (BEMA) model, or a nk-offset model.

9. The system of claim 1 , wherein a particular one of the effective medium models describes a portion of the plurality of the first structures in a particular one of the spatially-continuous regions as one or more films.

10. The system of claim 9 , wherein the one or more measurements comprises:
a metrology measurement.

11. The system of claim 10 , wherein the metrology measurement comprises:
at least one of an overlay measurement, a critical dimension (CD) measurement, a shape measurement, a stress measurement, a composition measurement, a bandgap measurement, a measurement of electrical properties, or a measurement of process conditions.

12. The system of claim 9 , wherein developing the effective medium model for at least one the spatially-continuous regions comprises:
determining at least one of dispersions or thicknesses of the one or more films through fitting to match the corresponding optical measurement data for the one or more training samples after the first process step.

13. The system of claim 1 , wherein the measurement models are based on light-matter interactions with the CuA devices.

14. The system of claim 1 , wherein the measurement models include machine learning models trained at least in part on synthesized data from models based on light-matter interactions with the CuA devices.

15. The system of claim 1 , wherein performing the unsupervised clustering of the optical measurement data for the one or more training samples after the first process step to identify the spatially-continuous regions is implemented using at least one of a k-nearest neighbor algorithm, a support vector machine, or a neural network.

16. The system of claim 1 , further comprising:
training a machine learning model based on the optical measurement data for the one or more training samples after the second process step and labels associated with the spatially-continuous regions based on unsupervised clustering of the optical measurement data for the one or more training samples after the first process step;
wherein generating the values of the one or more metrology measurements of the second structures on the one or more test samples based on the optical measurement data for the one or more test samples and the measurement models comprises:
selecting, for each location on the one or more test samples, one of the measurement models using the machine learning model with the associated optical measurement data from the locations on the one or more test samples; and
generating, for each location on the one or more test samples, values of the one or more metrology measurements based on the optical measurement data for the one or more test samples and the selected one of the measurement models.

17. The system of claim 1 , wherein the optical measurement data for at least one of the training samples after the first process step or after the second process step and the one or more test samples comprises:
at least one of ellipsometry data, reflectometry data, or scatterometry data.

18. A system, comprising:
an optical characterization system; and
a controller communicatively coupled with the optical characterization system, the controller including one or more processors configured to execute program instructions causing the one or more processors to implement a measurement recipe by:
receiving optical measurement data for one or more training samples after a first process step for fabricating complementary metal-oxide-semiconductor (CMOS) under array (CuA) devices from the optical characterization system, wherein the CuA devices include first structures with a non-uniform spatial distribution after the first process step;
classifying the first structures into spatially-continuous regions based on unsupervised clustering of the optical measurement data for the one or more training samples after the first process step;
receiving optical measurement data for the one or more training samples after a second process step for fabricating the CuA devices from the optical characterization system, wherein the CuA devices after the second process step include periodic second structures above the first structures;
developing effective medium models for the spatially-continuous regions of the first structures;
developing measurement models for determining one or more measurements of the CuA devices based on the effective medium models for the spatially-continuous regions of the first structures and the optical measurement data for the one or more training samples after the second process step;
receiving optical measurement data for one or more test samples after the second process step for fabricating the CuA devices from the optical characterization system; and
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Assignees

• Kla Corp

Inventors

• Kudyshev Zhaxylyk
• Chang Chao
• Shaughnessy Derrick A
• Chouaib Houssam

Classifications

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P72/0604 Primary

  Process monitoring, e.g. flow or thickness monitoring · CPC title

• G06F30/30

  Circuit design · CPC title

• G06F30/27

  using machine learning, e.g. artificial intelligence, neural networks, support vector machines [SVM] or training a model · CPC title