Lithography Process Window Tracker for Optics Deformation

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Solution Overview

Problem

Lithography processes face challenges in maintaining a stable process window due to variations in processing parameters such as deformation of projection optics caused by temperature changes and other environmental factors, leading to potential defects in pattern formation.

Innovation Solution

A computer-implemented method adjusts the first group of processing parameters, such as focus and dose, based on changes in the second group of parameters, including deformation of projection optics and temporal variations, to maintain the process window at or near its center, thereby ensuring robustness and enlarging the sub-process window.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If processing parameters are adjusted to compensate for environmental changes, then process window stability is improved, but system complexity increases

Engineering Contradiction:

Improveprocess window stabilityVSAvoidparameter adjustment system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system continuously monitors processing parameters and automatically adjusts them based on detected deviations from optimal values. Sensors detect changes in environmental conditions and processing parameters, and control algorithms compute and apply compensatory adjustments to maintain process window stability, creating a closed-loop feedback system that improves reliability without requiring manual intervention

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically modifies processing parameters such as focus, dose, and exposure conditions in response to detected environmental changes. By changing parameters adaptively rather than maintaining fixed values, the system compensates for variations in temperature, humidity, and equipment drift, thereby stabilizing the process window while managing complexity through automated parameter optimization

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the process window is maintained at optimal conditions, then manufacturing precision is improved, but adaptability to environmental changes deteriorates

Engineering Contradiction:

Improvepattern formation precisionVSAvoidenvironmental variation tolerance

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The system transitions from static, fixed process parameters to dynamic, adaptive parameters that automatically adjust to environmental conditions. By making the parameter set flexible and responsive rather than rigid and fixed, the system maintains manufacturing precision under varying conditions, effectively resolving the contradiction between precision and adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs real-time modification of processing parameters including focus offset, exposure dose, and illumination conditions to compensate for environmental variations. These parameter changes enable the system to adapt to changing conditions while maintaining pattern formation precision, as the parameters are continuously optimized rather than held constant

Inventive Principle:

Principle #35Parameter changes

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 helps maintain the process window at optimal conditions, reducing the likelihood of defects and enhancing the robustness of the lithography process by adjusting parameters to compensate for changes in the lithography environment.

Implementation Method 1

the deformation is caused by a temperature change of the projection optics of a lithography apparatus used in the lithography process. The temperature change is a result of exposure to radiation from a source of the lithography apparatus.

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10866523B2Process window tracker

Publication Date: 2020.12.15 ASML NETHERLANDS BV

AI summary

A method for adjusting a lithography process, wherein processing parameters of the lithography process include a first group of processing parameters and a second group of processing parameters, the method including: obtaining a change of the second group of processing parameters; determining a change of a sub-process window (sub-PW) as a result of the change of the second group of processing parameters, wherein the sub-PW is spanned by only the first group of processing parameters; and adjusting the first group of processing parameters based on the change of the sub-PW.