Image Evaluation Apparatus for Semiconductor Defect Classification

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Solution Overview

Problem

Convolutional Neural Networks (CNN) used in semiconductor inspection often misrecognize unknown defects due to limited training data, leading to potential overlooking of fatal defects and reduced yield.

Innovation Solution

An image evaluation apparatus and method that utilizes multiple classifiers and an evaluation unit to classify defect information by comparing image-of-interest information with defect region information, preventing misrecognition by machine learning models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If CNN is used for defect classification in semiconductor inspection, then classification accuracy for known defects is improved, but misrecognition of unknown defects occurs frequently

Engineering Contradiction:
Improveclassification accuracyVSAvoidmisrecognition rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an evaluation unit as an intermediary component that assesses the reliability of CNN classification results. This evaluation unit detects uncertain classifications and refers them to alternative processing methods, preventing misrecognition of unknown defects while maintaining high accuracy for known defects.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system dynamically adjusts its classification approach based on the confidence level of the CNN. For high-confidence predictions, the CNN result is accepted; for low-confidence predictions, the system switches to alternative processing methods, optimizing both accuracy and reliability adaptively.

Inventive Principle:
Principle #15Dynamics

2Productivity

If training data is limited to common defect types, then CNN learning efficiency is improved, but detection of rare defects becomes difficult

Engineering Contradiction:
Improvelearning efficiencyVSAvoiddefect type coverage
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The evaluation unit serves multiple functions: it identifies unknown defects, assesses classification confidence, and routes uncertain cases to alternative processing. This multi-functional component enables the system to handle both common and rare defects effectively without requiring extensive retraining.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system performs preliminary evaluation of classification confidence before finalizing defect identification. By pre-assessing the reliability of CNN predictions, the system can prepare alternative processing methods in advance for uncertain cases, improving detection of rare defects without sacrificing learning efficiency.

Inventive Principle:
Principle #10Preliminary action

3Speed

If machine learning model confidence is high, then classification speed is improved, but misrecognition of unknown defects increases

Engineering Contradiction:
Improveclassification speedVSAvoidmisrecognition rate
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The evaluation unit provides feedback on the reliability of CNN classification results. This feedback mechanism allows the system to identify and correct potential misrecognitions while maintaining fast processing for reliable classifications, balancing speed and accuracy.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts its processing path based on confidence assessment. High-confidence predictions are processed quickly through the CNN, while low-confidence predictions trigger additional evaluation steps, optimizing the trade-off between speed and reliability.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS12100133B2Image evaluation apparatus and image evaluation method
Publication Date: 2024.09.24 HITACHI HIGH TECH CORP
  • US12100133B2 patent drawing
  • US12100133B2 patent drawing
  • US12100133B2 patent drawing

AI summary

The purpose of the present invention is to provide an image evaluation device and method which can detect unknown defects and which can prevent misrecognition by a machine learning model. This image evaluation device, which uses a machine learning classifier to classify defect information in a defect image of an electronic device, is characterized by being provided with: an image storage unit which stores a defect image of an electronic device; a defect region storage unit which stores defect region information that is in the defect image; a classifier which classifies the defect information with machine learning; an image extraction unit which, in the course of the defect image classification processing, extracts image-of-interest information which the classifier will focus on; and an evaluation unit which compares the image-of-interest information and the defect region information to evaluate the classifiability of the defect image.