Lithographic Apparatus Drift Compensation

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Solution Overview

Problem

Lithographic apparatuses face challenges in maintaining uniformity of the illumination beam due to drift caused by heat absorption and component expansion, leading to manufacturing defects and reduced imaging quality.

Innovation Solution

A system with at least two sensors measures properties of the illumination region, determining drift relative to a reference position, and a processor calculates drift corrections to be applied through a uniformity compensator system, adjusting the illumination beam to maintain uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the lithographic apparatus operates continuously to maximize manufacturing capacity, then productivity is improved, but thermal-induced drift and uniformity degradation occur

Engineering Contradiction:

Improvemanufacturing capacityVSAvoidillumination uniformity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where sensors continuously monitor the illumination beam properties, and the system automatically adjusts uniformity compensators based on detected drift. This closed-loop control enables continuous operation while maintaining uniformity through real-time corrections.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary drift compensation by detecting illumination variations and adjusting compensators before the drift significantly impacts imaging quality. This proactive approach allows continuous operation without compromising reliability.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If uniformity correction devices with larger actuating fingers are used to correct intensity variations, then manufacturing precision is improved, but the pupil formed by the radiation beam is compromised

Engineering Contradiction:

Improveintensity uniformity correctionVSAvoidpupil formation

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent uses multiple smaller actuating fingers distributed across the illumination beam rather than a single large finger. Each finger locally corrects intensity variations in its specific region, achieving overall uniformity without compromising the global pupil shape.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The uniformity correction system is segmented into multiple independent actuating fingers that can be controlled individually. This segmentation allows precise local adjustments without the mechanical constraints of a single large actuator, maintaining both correction effectiveness and pupil integrity.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If additional uniformity refreshes are performed per wafer to correct drift, then imaging quality is improved, but manufacturing time and costs increase

Engineering Contradiction:

Improveimaging qualityVSAvoidmanufacturing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent implements continuous drift monitoring and compensation during wafer exposure without interrupting the manufacturing process. The uniformity correction operates continuously in the background, eliminating the need for time-consuming uniformity refreshes between wafers while maintaining imaging quality.

Inventive Principle:

Principle #20Continuity of useful action

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 improves imaging quality by minimizing dose drift and maintaining desired uniformity, reducing manufacturing defects and costs by continuously correcting for thermal-induced drift without requiring additional uniformity refreshes per wafer.

Implementation Method 1

The uniformity correction devices may employ actuated fingers which are inserted into an edge of a radiation beam to correct intensity variations

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

the lithographic apparatus absorbs heat which causes expansion of the apparatus's components leading to drift, movement, and uniformity changes

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20230035511A1Lithographic apparatus and method for drift compensation

Publication Date: 2023.02.02 ASML HLDG NV

AI summary

A system, method, a lithographic apparatus and a software product configured to determine a drift in an attribute of an illumination and a corresponding drift correction. The system includes a lithographic apparatus that includes at least two sensors, each configured to measure a property related to an illumination region provided for imaging a substrate. Furthermore, a processor is configured to: determine, based on a ratio of the measured property, a drift of the illumination region with respect to a reference position; determine, based on the drift of the illumination region, a drift in an attribute related to the illumination upstream of the illumination region measured by the at least two sensors, and determine, based on the drift in the attribute, the drift correction to be applied to the attribute to compensate for the drift in the attribute.