Matching Pupil Determination for Lithographic Apparatus
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Solution Overview
Problem
Lithographic apparatuses experience performance variations due to changes in pupil facet mirrors over time, leading to inconsistencies in critical dimension and overlay, which affect the quality and consistency of patterned substrates.
Innovation Solution
A method is implemented to determine a matching pupil by selecting initial leading degrees of freedom from pupil facet mirrors and adjusting their orientation and intensity based on exposure data, iteratively minimizing the difference between the apparatus' performance and a reference performance, thereby maintaining consistent output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pupil facet mirrors are used in the lithographic apparatus, then the apparatus can achieve high manufacturing precision for critical dimension and overlay, but the performance varies over time due to changes in the mirrors
Solution Approach 1:
The patent determines a matching pupil configuration before production runs to predict and prevent performance variations. By calculating the optimal pupil facet mirror orientations and intensities in advance based on reference apparatus data, the system prepares compensation parameters that will maintain manufacturing precision throughout production, addressing the reliability issue before it manifests.
Solution Approach 2:
The patent establishes a feedback mechanism where exposure data from actual production is compared against reference performance data. The system uses this feedback to determine updated matching pupil configurations that compensate for drift in pupil facet mirror performance, thereby maintaining consistent critical dimension and overlay precision over time.
2Reliability
If pupil facet mirror adjustments are made to match reference performance, then performance consistency is improved, but the complexity of the apparatus increases
Solution Approach 1:
The patent creates a virtual model or copy of the reference apparatus performance characteristics and uses this model to determine matching pupil configurations. By working with computational models rather than directly manipulating physical mirror adjustments, the system achieves performance matching while reducing the operational complexity of the physical apparatus.
Solution Approach 2:
The patent transforms the complex physical problem of pupil facet mirror alignment into a parameter optimization problem. By representing the pupil configuration as a set of adjustable parameters (orientations and intensities) and using computational methods to find optimal values, the system simplifies the control complexity while maintaining the ability to achieve precise performance matching.
3Manufacturing precision
If iterative adjustment of pupil facet mirrors is performed, then the difference between apparatus performance and reference performance is reduced, but the time required for setup and reconfiguration increases
Solution Approach 1:
The patent performs preliminary determination of the matching pupil configuration before production begins. By calculating the optimal pupil settings in advance using reference performance data and exposure data from initial runs, the system avoids time-consuming iterative adjustments during production, thus reducing setup time while maintaining high precision.
Solution Approach 2:
The patent implements a dynamic pupil determination system that can adapt to changing conditions. The system uses exposure data collected during production to update the matching pupil configuration when performance drift is detected, allowing the system to maintain high precision without requiring frequent manual reconfiguration, thus balancing accuracy with time efficiency.
Data Source
AI summary
A method for reducing apparatus performance variation. The method includes obtaining (i) a reference performance (e.g., CD) of a reference apparatus (e.g, a reference scanner), (ii) a set of initial leading degrees of freedom selected from a plurality of degrees of freedom of a plurality of pupil facet mirrors of an apparatus (e.g., to be matched scanner) that is selected to reproduce the reference performance, and (iii) exposure data related to one or more parameters (e.g., CD, overlay, focus, etc.) of the patterning process indicating a performance of the apparatus based on the set of initial leading degrees of freedom; and determining a matching pupil of the apparatus based on the set of initial leading degrees of freedom and the exposure data such that the matching pupil reduces a difference between the performance of the apparatus and the reference performance.