Zernike Polynomial Substrate Reference Image Creation

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Solution Overview

Problem

Conventional defect inspection methods in semiconductor manufacturing are prone to false defects due to color unevenness, and the creation of a substrate reference image can vary based on operator skill, leading to inconsistent inspection results.

Innovation Solution

The method involves decomposing substrate images using Zernike polynomials to calculate coefficients, extracting median and deviated values, and combining specified images to create a reference image with filtering capabilities against color unevenness, ensuring consistent defect inspection regardless of operator skill.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If substrate images with color unevenness are combined to create a reference image, then false defects are filtered out, but the reference image creation becomes subjective and inconsistent

Engineering Contradiction:
Improvedefect inspection accuracyVSAvoidreference image consistency
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent transforms the subjective image selection process into an objective mathematical process by changing parameters from operator judgment to Zernike polynomial coefficients. By decomposing images into standardized mathematical components and using automated coefficient comparison, the system eliminates operator skill variability while maintaining the ability to filter false defects through systematic selection of images with representative color unevenness patterns.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/manual process of operator-based image selection with an automated computational system. Instead of operators manually selecting and combining images based on empirical rules, the system uses Zernike polynomial decomposition and automated coefficient analysis to objectively select and combine images, substituting human judgment with mathematical algorithms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If operator skill level varies, then reference image creation quality varies, but automation increases device complexity

Engineering Contradiction:
Improvereference image consistencyVSAvoidimage processing system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent introduces Zernike polynomials as an intermediary mathematical framework that bridges the gap between simple image combination and complex automated processing. The polynomials serve as a standardized intermediate representation that enables objective comparison and selection of substrate images through coefficient analysis, providing a systematic mediator between the input images and the final reference image.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the image processing task into distinct mathematical components using Zernike polynomial decomposition. By breaking down the complex image data into standardized polynomial coefficients representing different spatial frequencies and patterns, the system enables systematic and automated selection criteria, transforming a holistic subjective judgment into separable objective measurements.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS9146479B2Substrate reference image creation method, substrate defect inspection method, substrate reference image creation apparatus, substrate defect inspection unit and non-transitory computer storage medium
Publication Date: 2015.09.29 TOKYO ELECTRON LTD
  • US9146479B2 patent drawing
  • US9146479B2 patent drawing
  • US9146479B2 patent drawing

AI summary

In the present invention, a planar distribution of pixel values in a picked-up substrate image is decomposed into a plurality of pixel value distribution components through use of a Zernike polynomial for each of substrate images; Zernike coefficients of the pixel value distribution components decomposed through use of the Zernike polynomial are calculated; a median value and values deviated from the median value by a predetermined value or more are extracted for every Zernike coefficients having a same couple of degrees from the calculated Zernike coefficients; substrate images having the extracted values are specified; and a substrate image being a defect inspection reference is created by combining the specified substrate images.