Substrate Distortion Measurement for Device-Region Overlay Accuracy

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Solution Overview

Problem

Existing methods for measuring overlay accuracy in semiconductor manufacturing fail to accurately measure the device region due to distortion differences between the device and peripheral regions, leading to errors in periodic pattern measurements.

Innovation Solution

A method that captures images of partial regions within the device region, determines the pattern period, and corrects measurement results using substrate stage position information to measure distortion accurately.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If alignment marks are arranged in the peripheral region surrounding the device region, then overlay accuracy can be improved, but measurement accuracy of the device region decreases due to distortion differences between peripheral and device regions

Engineering Contradiction:

Improveoverlay accuracyVSAvoidmeasurement accuracy of device region

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent extracts the measurement function from the peripheral alignment marks and relocates it directly to the device region by forming measurement patterns within the device region itself. This allows direct measurement of the device region distortion without being affected by the distortion differences between peripheral and device regions, thereby resolving the contradiction between improving overlay accuracy and maintaining measurement accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces measurement patterns as an intermediary element within the device region. These measurement patterns serve as a mediator that enables direct measurement of device region distortion while being formed using the same lithography process, thus bridging the gap between overlay improvement requirements and accurate device region measurement needs.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If periodic patterns are formed in the device region for direct measurement, then measurement of device region can be achieved, but errors arise due to period of the periodic pattern which decreases measurement accuracy

Engineering Contradiction:

Improvemeasurement accuracy of device regionVSAvoidmeasurement accuracy affected by pattern period

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent changes the measurement approach by not relying on the absolute period of periodic patterns. Instead, it measures relative positional deviations of measurement patterns at different locations within the device region. This parameter change from absolute to relative measurement eliminates errors caused by periodic pattern period variations while maintaining the ability to directly measure device region distortion.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If the entire device region is measured directly, then measurement accuracy improves, but measurement time and complexity increase

Engineering Contradiction:

Improvemeasurement accuracy of device regionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the device region into multiple measurement locations with distributed measurement patterns. By measuring at strategically selected locations rather than attempting to measure the entire device region uniformly, the method achieves accurate distortion measurement while reducing measurement time and complexity through selective sampling of representative regions.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables precise measurement of substrate distortion, improving overlay accuracy and reducing measurement errors in semiconductor manufacturing.

Implementation Method 1

an imaging device to capture images of a plurality of partial regions of a pattern formed in a device region of the substrate

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS20250348007A1Measuring method, storage medium, measuring device, lithography apparatus, and article manufacturing method

Publication Date: 2025.11.13 CANON KK

AI summary

A measuring method for measuring distortion of a substrate includes capturing images of a plurality of partial regions of a pattern formed in a device region of the substrate, measuring a position of the pattern based on the images acquired by the image capturing, and processing of determining a period of the pattern based on the images acquired by the image capturing, and determining distortion in the region of the substrate where the pattern is formed, based on the determined period and a measurement result acquired in the measuring.