Simulation-Assisted Metrology Alignment for Lithography
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Solution Overview
Problem
Current methods for monitoring patterning processes in lithographic apparatuses face challenges in accurately measuring parameters like edge placement errors due to uncertainties in aligning metrology images with design layouts, especially when resolution enhancement techniques and patterning device inaccuracies introduce deviations.
Innovation Solution
A method that simulates images using design layout and patterning process characteristics, determines deviations, aligns metrology images with design layouts based on these deviations, and adjusts the design layout or patterning process to minimize errors, using techniques like resolution enhancement and assist features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional alignment methods are used between metrology images and design layouts, then the alignment process is simple, but measurement precision deteriorates due to uncertainties from resolution enhancement techniques and patterning device inaccuracies
Solution Approach 1:
The patent applies preliminary action by pre-simulating the patterning process to predict deviations between design layouts and actual patterned substrates before metrology measurement. This simulation step, performed using process models and design data, prepares correction information in advance that is then applied during alignment, improving measurement precision without adding complex real-time processing
Solution Approach 2:
The patent introduces an intermediary element - a simulation-based deviation model - that mediates between the design layout and the metrology image alignment process. This intermediary provides predicted deviation information that corrects the alignment between design and measurement data, resolving the contradiction by adding a computational layer that improves accuracy without requiring physical hardware changes
2Manufacturing precision
If resolution enhancement techniques are applied to improve patterning, then manufacturing precision improves, but deviations from design layout increase making alignment more difficult
Solution Approach 1:
The patent implements feedback by using simulation to predict the deviations introduced by resolution enhancement techniques, then applying this predicted deviation information to correct the alignment between design layouts and metrology images. This feedback loop compensates for the intentional deviations created by RET, maintaining both manufacturing precision and measurement accuracy
Solution Approach 2:
The patent applies parameter changes by modifying the alignment parameters based on simulated deviation data. Instead of assuming perfect alignment between design and measurement, the system adjusts alignment parameters to account for the specific deviations introduced by resolution enhancement techniques, thereby maintaining measurement precision despite manufacturing process modifications
Data Source
AI summary
A method including: simulating an image or characteristics thereof, using characteristics of a design layout and of a patterning process, determining deviations between the image or characteristics thereof and the design layout or characteristics thereof; aligning a metrology image obtained from a patterned substrate and the design layout based on the deviations, wherein the patterned substrate includes a pattern produced from the design layout using the patterning process; and determining a parameter of a patterned substrate from the metrology image aligned with the design layout.