Lithography Mark Measurement Using Sensitivity-Based Parameter Tuning

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Solution Overview

Problem

Existing lithography processes face challenges in achieving high measurement accuracy due to variations in mark physical properties and structures, leading to suboptimal detection signal intensity and quality when parameter values deviate from optimal settings.

Innovation Solution

A method involving preliminary measurement with varying parameter combinations to determine sensitivity distributions, followed by setting optimal parameter values for accurate main measurement, using a measuring apparatus with a wavelength variable unit to adjust light parameters for precise alignment and overlay detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If parameter values are fixed without optimization, then measurement process is simple, but measurement accuracy decreases due to suboptimal detection signal intensity and quality

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidmeasurement process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent performs preliminary measurement to obtain sensitivity distributions before conducting the actual measurement. This preliminary action identifies optimal parameter values in advance, ensuring that the main measurement process uses optimized settings that maximize detection signal intensity and quality, thereby resolving the contradiction between measurement accuracy and process complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent systematically varies measurement parameters (such as wavelength, numerical aperture, and illumination conditions) to construct sensitivity distributions. By analyzing how measurement values change with parameter variations, the system identifies optimal parameter combinations that maximize measurement accuracy while providing a systematic approach to handling the complexity of parameter optimization.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple parameter combinations are tested to find optimal settings, then measurement accuracy improves, but measurement time increases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The sensitivity distribution measurement is performed as a preliminary step that can be conducted once for a given mark type and measurement condition. Once obtained, this sensitivity distribution information can be reused for multiple measurements under similar conditions, reducing the need to repeatedly test multiple parameter combinations and thereby minimizing the time penalty while maintaining high measurement accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses the obtained sensitivity distribution to automatically determine optimal parameter values without requiring manual intervention or repeated trial-and-error measurements. This self-service approach allows the measurement system to autonomously select optimal parameters based on pre-acquired sensitivity information, significantly reducing measurement time while maintaining accuracy.

Inventive Principle:

Principle #25Self-service

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

Enhances measurement accuracy by optimizing parameter settings, ensuring high signal intensity and quality, thereby improving alignment and overlay precision in lithography processes.

Implementation Method 1

A measuring unit 50 performs preliminary measurement

Methodology Applied

Scientific EffectOptical detection:

Implementation Method 2

using a measuring apparatus with a wavelength variable unit to adjust light parameters

Methodology Applied

Scientific EffectWavelength adjustment:

Data Source

PatentUS12578181B2Measuring method, measuring apparatus, lithography apparatus, and article manufacturing method

Publication Date: 2026.03.17 CANON KK

AI summary

A measuring method includes performing preliminary measurement, while changing a combination of parameter values of at least two different measurement parameters, concerning each combination, performing processing to obtain a sensitivity distribution as a distribution of sensitivities indicating a change in measurement value with a change in parameter value concerning each of the at least two measurement parameters based on measurement values obtained in the performing preliminary measurement, determining a parameter value to be used concerning each of the at least two measurement parameters based on the sensitivity distribution concerning each of the at least two measurement parameters, and performing main measurement in accordance with the parameter value of each of the at least two measurement parameters determined in the determining.