Aberration Sensitivity Mapping for Process Window Limiting Patterns

Solution Overview

Problem

Existing methods for determining aberration sensitivity of patterns in lithographic processes are computationally intensive and require significant pre-processing, limiting their efficiency and accuracy in identifying hotspots and optimizing patterning processes.

Innovation Solution

The method involves obtaining first and second sets of Zernike cross coefficient (ZCC) kernels associated with the aberration wavefront of a patterning apparatus, and using these kernels to determine an aberration sensitivity map for a design layout. This map indicates the sensitivity of pattern portions to individual aberrations and their interactions, allowing for the identification of process window limiting patterns (PWLP).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing methods for determining aberration sensitivity are used, then measurement precision is improved, but computational complexity and processing time increase significantly

Engineering Contradiction:

Improveaberration sensitivity measurement precisionVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the aberration sensitivity determination into distinct computational stages: (1) obtaining Zernike coefficients representing wavefront aberrations, (2) calculating sensitivity metrics for different pattern features, (3) identifying hotspots based on sensitivity thresholds. This segmentation allows each stage to be optimized independently and enables early termination when sufficient precision is achieved, reducing overall computational complexity while maintaining measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary calculations of Zernike coefficients and aberration characteristics before analyzing specific design layouts. By pre-computing the wavefront aberration parameters and sensitivity models, the method avoids redundant calculations during the actual hotspot identification process, significantly reducing processing time while preserving measurement accuracy.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If existing methods for determining aberration sensitivity are used, then measurement precision is improved, but processing time increases significantly

Engineering Contradiction:

Improveaberration sensitivity measurement precisionVSAvoidprocessing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary calculations of Zernike coefficients and aberration characteristics before analyzing specific design layouts. By pre-computing the wavefront aberration parameters and sensitivity models, the method avoids redundant calculations during the actual hotspot identification process, significantly reducing processing time while preserving measurement accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a tiered analysis approach where only the most sensitive pattern features are analyzed in detail, while less sensitive features are evaluated with simplified models or excluded from detailed analysis. This partial action strategy focuses computational resources on critical areas, reducing overall processing time while maintaining precision where it matters most for hotspot identification.

Inventive Principle:

Principle #16Partial or excessive action

3Manufacturing precision

If comprehensive aberration sensitivity analysis is performed, then manufacturing precision is improved, but computational resources required increase

Engineering Contradiction:

Improvepatterning process precisionVSAvoidcomputational resources

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements a tiered analysis approach where only the most sensitive pattern features are analyzed in detail, while less sensitive features are evaluated with simplified models or excluded from detailed analysis. This partial action strategy focuses computational resources on critical areas, reducing overall processing time while maintaining precision where it matters most for hotspot identification.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent applies different levels of analysis depth to different regions of the design layout based on their sensitivity characteristics. High-sensitivity regions receive comprehensive analysis with full aberration models, while low-sensitivity regions use simplified evaluation. This local quality approach optimizes computational resource allocation by matching analysis intensity to actual manufacturing precision requirements in each local area.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20250155824A1Method for determining aberration sensitivity of patterns

Publication Date: 2025.05.15 ASML NETHERLANDS BV

AI summary

A method for determining process window limiting patterns based on aberration sensitivity associated with a patterning apparatus. The method includes obtaining (i) a first set of kernels and a second set of kernels associated with an aberration wavefront of the patterning apparatus and (ii) a design layout to be printed on a substrate via the patterning apparatus; and determining, via a process simulation using the design layout, the first set of kernels, and the second set of kernels, an aberration sensitivity map associated with the aberration wavefront, the aberration sensitivity map indicating how sensitive one or more portions of the design layout are to an individual aberrations and an interaction between different aberrations; determining, based on the aberration sensitivity map, the process window limiting pattern associated with the design layout having relatively high sensitivity compared to other portions of the design layout.