Pattern Height Correction Using AFM Curved Surface Approximation

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Solution Overview

Problem

Existing systems for evaluating pattern height information in semiconductor manufacturing struggle to accurately exclude local shifts caused by atmospheric pressure variations and vibrations, which can superimpose on macro displacement corrections.

Innovation Solution

A pattern height information correction system that uses contour line information from atomic force microscope images, a design information database, and a computer system to divide patterns into regions, specify horizontal regions, create approximated curved surfaces, and correct height information using these surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If macro displacement correction is applied using Z-direction correction means, then macro variation in Z-direction is corrected, but local shift amount due to atmospheric pressure variation and vibration cannot be excluded

Engineering Contradiction:

Improveheight information accuracyVSAvoidlocal shift amount

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent segments the height information correction process into two distinct components: macro displacement correction (using Z-direction correction means) and local shift correction (using the invention's method). By dividing the correction task into separate steps, the system can address both macro variation and local shift caused by atmospheric pressure and vibration, thereby resolving the contradiction between correcting macro displacement and excluding local shift effects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by first performing macro displacement correction using Z-direction correction means, and then subsequently applying local shift correction based on the relationship between measured height information and design height information. This sequential approach ensures that both types of errors are corrected in order, improving overall measurement precision while accounting for both macro and local variations.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If Z-direction scanner drive amount is corrected based on correction data, then macro Z-direction variation is compensated, but local shift superimposed on macro displacement remains uncorrected

Engineering Contradiction:

Improvepattern height informationVSAvoidheight information accuracy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements feedback by comparing the measured height information with the design height information to detect local shifts, and then using this feedback to correct the height information. The system continuously monitors the discrepancy between measured and design values, and applies corrective adjustments accordingly, thereby improving manufacturing precision and reliability of height information even when local shifts are present.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces purely mechanical correction methods (Z-direction scanner adjustment) with a combined approach that includes computational correction. By substituting mechanical adjustment with a systematic method that uses design information and measured information comparison, the system can correct both macro displacement and local shift, thereby improving pattern height information accuracy and reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If inclined stage is used to correct inclination, then sample or scanner inclination is corrected, but local shift due to atmospheric pressure and vibration cannot be excluded

Engineering Contradiction:

Improveheight informationVSAvoidcorrection system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary computational method that processes the relationship between measured height information and design height information to identify and correct local shifts. This intermediary processing layer acts as a mediator between the physical measurement system and the final corrected output, enabling the system to exclude local shift effects without adding complex physical correction mechanisms, thereby maintaining measurement precision while avoiding increased device complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11448663B2Pattern height information correction system and pattern height information correction method

Publication Date: 2022.09.20 HITACHI HIGH TECH CORP

AI summary

This invention is directed to a pattern height information correction system which includes a contour line information of a pattern extracted from an acquired image including at least an AFM (atomic force microscope) module, a design information database that stores design information including at least layer information, and a computer system that divides the extracted pattern into regions based on the design information stored in the design information database relating to the extracted pattern and associates the divided regions with layer information, in which the computer system specifies a horizontal region designated as horizontal in advance from the divided regions, creates an approximated curved surface based on the specified horizontal region corresponding to the same layer information, and corrects height information of the extracted pattern using the approximated curved surface.