Alignment Mark Positioning With Geometrical Deformation Correction

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Solution Overview

Problem

Current methods for determining the position of alignment marks in lithographic processes are inaccurate, leading to errors in substrate positioning and pattern reproduction, especially in low-k1 lithography where feature sizes approach the resolution limit, and require sophisticated fine-tuning and control loops to achieve desired electrical functionality and performance.

Innovation Solution

A method and apparatus that determine the position of alignment marks by obtaining an expected position and accounting for geometrical deformations caused by control actions, such as heating of lenses, reticles, or substrates, using metrology data and Advanced Process Control strategies to correct field geometry properties like overlay, allowing for precise alignment and positioning of substrates during lithographic processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If alignment mark positions are measured with an alignment sensor in a scanner reference grid and mapped to positions defined in the exposure job, then substrate positioning accuracy is improved, but errors remain due to geometrical deformations from control actions like heating

Engineering Contradiction:

Improvealignment mark position determination accuracyVSAvoidpattern reproduction accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by obtaining the geometrical deformation of the region due to control actions (such as heating of lenses, reticles, or substrates) before determining the final alignment mark position. The expected position is adjusted by the calculated translation resulting from geometrical deformation, proactively compensating for errors before they affect pattern reproduction accuracy.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If control actions are applied to correct lithographic process errors (such as heating corrections), then manufacturing precision is improved, but alignment mark positions become inaccurate due to geometrical deformation of the region

Engineering Contradiction:

Improvepattern reproduction precisionVSAvoidalignment mark position measurement accuracy

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The patent implements feedback by using metrology data to determine geometrical deformation of the region caused by control actions. This deformation information is fed back into the alignment mark position calculation, allowing the system to compensate for position shifts resulting from heating or other control actions, thereby maintaining both manufacturing precision and measurement accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies parameter changes by adjusting the expected position of the alignment mark based on the calculated translation from geometrical deformation. The position parameters are dynamically modified to account for thermal expansion or contraction and other deformation effects, ensuring accurate alignment despite changes in physical dimensions caused by control actions.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If static offsets are measured and corrected by an overlay feed-back control loop, then overlay accuracy is improved, but errors are still present due to dynamic geometrical deformations

Engineering Contradiction:

Improveoverlay accuracyVSAvoidalignment accuracy

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent transitions from static offset correction to dynamic correction by continuously accounting for geometrical deformation of the region caused by control actions. The system dynamically calculates the translation of alignment marks based on real-time or near-real-time deformation data, enabling accurate compensation for both static and dynamic position shifts throughout the lithographic process.

Inventive Principle:

Principle #15Dynamics

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 enhances the accuracy of alignment mark positioning, reducing errors and improving the reproduction of patterns on substrates, thereby maintaining process stability and achieving tighter control over feature dimensions and placement, even in low-k1 lithography.

Implementation Method 1

obtaining a geometrical deformation of the region due to a control action correcting the lithographic process... obtaining a translation of the alignment mark due to the geometrical deformation

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11294294B2Alignment mark positioning in a lithographic process

Publication Date: 2022.04.05 ASML NETHERLANDS BV

AI summary

Methods and apparatuses for determining a position of an alignment mark applied to a region of a first layer on a substrate using a lithographic process by: obtaining an expected position of the alignment mark; obtaining a geometrical deformation of the region due to a control action correcting the lithographic process; obtaining a translation of the alignment mark due to the geometrical deformation; and determining the position of the alignment mark based on the expected position and the translation.