Metrology Data Correction via Invariant Transform

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current metrology techniques in the lithographic process face challenges in accurately measuring small features due to the limitations of existing radiation wavelengths, leading to inaccurate measurements and inefficiencies in process control, particularly with the drift of parameters such as detector position and illumination angles.

Innovation Solution

A method involving the use of measurement data correction based on an approximately invariant transformation of structure response metrics, combined with a trained forward model to infer parameter values from scattered radiation, allowing for precise measurements even with varying drift parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing radiation wavelengths are used for metrology measurements, then the measurement process is simple, but the measurement precision of small features deteriorates

Engineering Contradiction:

Improvemeasurement precisionVSAvoidmeasurement process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by transforming the measurement data using an approximately invariant transformation that accounts for drift parameters. This transformation adjusts the measurement data based on variations in detector position, illumination angles, and other drift parameters, thereby maintaining measurement precision without requiring changes to the physical measurement setup or radiation wavelength.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If drift parameters such as detector position and illumination angles are not corrected, then the measurement process is fast, but the measurement precision deteriorates

Engineering Contradiction:

Improvemeasurement precisionVSAvoidmeasurement time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements preliminary action by pre-calculating and storing the approximately invariant transformation parameters for various drift parameter combinations. During actual measurements, the system quickly retrieves and applies the appropriate transformation based on measured drift parameters, avoiding time-consuming real-time calculations while maintaining measurement precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system employs feedback by continuously monitoring drift parameters such as detector position and illumination angles, and using this information to correct measurement data through the approximately invariant transformation. This closed-loop approach ensures measurement precision is maintained despite parameter drift, while the efficient transformation algorithm minimizes correction time.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If dedicated metrology targets are used, then the measurement process is straightforward, but the adaptability to different feature sizes deteriorates

Engineering Contradiction:

ImproveadaptabilityVSAvoidmeasurement setup complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent achieves universality by developing an approximately invariant transformation method that can correct measurement data for various feature sizes and types using the same fundamental approach. The transformation framework is adaptable to different metrology target configurations and feature dimensions, eliminating the need for specialized measurement procedures for each target type while maintaining measurement accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This approach enables more accurate and reliable measurements of small features by mitigating the impact of drift parameters, improving the precision of process control and reducing measurement inaccuracies.

Implementation Method 1

obtaining measurement data relating to at least one measurement of each of one or more structures on a substrate; correcting the measurement data based on an approximately invariant transformation

Methodology Applied

Scientific EffectScattered radiation detection: Scattering

Data Source

PatentUS20230040124A1Method for correcting measurements in the manufacture of integrated circuits and associated apparatuses

Publication Date: 2023.02.09 ASML NETHERLANDS BV

AI summary

Disclosed is a method of metrology. The method comprises illuminating a radiation onto a substrate; obtaining measurement data relating to at least one measurement of each of one or more structures on the substrate; using a Fourier-related transform to transform the measurement data into a transformed measurement data; and extracting a feature of the substrate from the transformed measurement data, or eliminating an impact of a nuisance parameter.