Workpiece Overlay Compensation via Local Z-Shape Measurement
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Solution Overview
Problem
Existing methods for manufacturing photomasks and other workpieces face challenges in achieving accurate overlay between layers due to workpiece deformation during patterning steps, which cannot be adequately compensated for using simple global parameters, especially in advanced multi-layer writing processes where precise alignment is critical.
Innovation Solution
The method involves acquiring the Z-shape of the workpiece before and after patterning, calculating compensation values based on these measurements, and updating the reference grid to compensate for distortions, allowing for improved alignment between layers without introducing additional alignment marks or affecting absolute registration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If simple global parameters are used for alignment compensation, then the process is simple, but overlay accuracy deteriorates due to workpiece deformation
Solution Approach 1:
The patent divides the workpiece surface into multiple measurement regions with local alignment marks, allowing separate measurement and compensation of deformation in each region. This segmentation enables accurate capture of local distortions that global parameters cannot detect, resolving the contradiction between simple process and high overlay accuracy.
Solution Approach 2:
The patent implements local measurement and compensation strategies where each region of the workpiece is measured and compensated independently based on its specific deformation characteristics. This local quality approach allows the system to adapt to varying deformation patterns across different areas, achieving high overlay accuracy without requiring complex global compensation models.
2Manufacturing precision
If additional alignment marks are introduced to improve measurement accuracy, then overlay precision improves, but device complexity and process complexity increase
Solution Approach 1:
The patent designs alignment marks that serve multiple functions: they act as both measurement references for deformation detection and as part of the functional pattern itself. This multi-functionality reduces the need for separate dedicated alignment marks, thereby improving overlay precision without significantly increasing device complexity.
Solution Approach 2:
The workpiece structure itself provides the alignment marks through its inherent features, eliminating the need for additional external alignment elements. The existing structural features are utilized as measurement references, allowing the workpiece to serve its own alignment needs without adding extra components.
3Device complexity
If rigid body assumption is made for workpiece, then calculation is simplified, but measurement precision deteriorates due to ignoring deformation
Solution Approach 1:
The patent transitions from assuming rigid body parameters to measuring and compensating for actual deformation parameters by acquiring Z-shape data at multiple points. This parameter change allows the system to account for workpiece deformation while maintaining manageable calculation complexity through systematic data acquisition and processing methods.
Data Source
AI summary
Methods and apparatuses for patterning workpieces are provided. The methods and apparatuses described herein improve overlay between subsequently patterned layers on a workpiece by introducing an improved alignment method that compensates for workpiece distortions.