Exposure Evaluation Device for High-Precision Focal Position Measurement

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Solution Overview

Problem

Conventional focal position evaluation methods in exposure devices are affected by variations in dose quantities and require dedicated evaluation patterns, making it difficult to precisely evaluate exposure conditions, especially when evaluating actual device patterns.

Innovation Solution

An evaluation device and method that illuminates a substrate with formed processing conditions, detects light from the substrate, and estimates exposure conditions using differing illumination and detection conditions, allowing for precise evaluation of processing conditions without the need for dedicated patterns.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional focal position evaluation method using a dedicated evaluation pattern is used, then the focal position can be evaluated, but the measurement results are affected by variations in dose quantities and other exposure conditions, reducing measurement precision

Engineering Contradiction:

Improvefocal position evaluation precisionVSAvoidevaluation reliability under varying exposure conditions

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention extracts and isolates the focal position information from the complex exposure process by using multiple illumination conditions. By taking measurements under different illumination angles and wavelengths, the method separates focal position effects from dose quantity variations, enabling precise focal position evaluation independent of other exposure condition variations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes multiple parameters including illumination angle, wavelength, and polarization state to perform measurements. By varying these parameters and analyzing the changes in reflected light characteristics, the system can determine focal position while compensating for variations in dose quantity and other exposure conditions.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a dedicated evaluation pattern is used for focal position evaluation, then evaluation can be performed, but it becomes difficult to evaluate actual device patterns

Engineering Contradiction:

Improveevaluation applicability to actual device patternsVSAvoidfocal position evaluation precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The invention creates a universal evaluation method that works for both dedicated evaluation patterns and actual device patterns. The multiple illumination condition approach is applicable to any pattern type, allowing the same measurement technique to be used across different evaluation scenarios without sacrificing precision or requiring pattern-specific procedures.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If multiple exposure conditions are managed with high precision, then exposure quality improves, but the complexity of evaluation increases

Engineering Contradiction:

Improveexposure condition control precisionVSAvoidevaluation system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention uses reflected light characteristics as an intermediary to indirectly measure focal position and other exposure conditions. Instead of directly measuring each parameter, the system measures the optical properties of reflected light under multiple illumination conditions, which contain encoded information about the exposure conditions, simplifying the evaluation process.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 high-precision evaluation of exposure conditions by suppressing the influence of other exposure conditions and allowing evaluation of actual device patterns, improving the accuracy and efficiency of exposure device settings.

Implementation Method 1

an illumination unit that illuminates, with illumination light, a substrate on which a structure has been formed with a plurality of sets of processing conditions... a detection unit that detects light coming from a processed surface of the substrate due to the illumination light

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS10274835B2Evaluation method and device, processing method, and exposure system

Publication Date: 2019.04.30 NIKON CORP

AI summary

Using a substrate on which a structure has been formed with a plurality of sets of processing conditions, the present disclosure provides an evaluation device that evaluates one of said sets of processing conditions with high precision. This evaluation device is provided with an illumination system that uses illuminating light to illuminate a wafer on which a pattern has been provided via exposure using a plurality of sets of exposure conditions, including first exposure conditions and second exposure conditions; a light-receiving system and an imaging unit the detect light coming from the surface of the wafer; and a computation unit that, on the basis of detection results obtained by the imaging unit using first diffraction conditions and second diffraction conditions that differ in terms of illumination conditions and/or detection conditions, and that estimates the first exposure conditions used when the wafer is exposed.