Tool Workpiece Alignment Using Native Surface Features
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Solution Overview
Problem
Current alignment systems in lithography and other tool-based systems face challenges in achieving precise alignment, especially when dealing with continuous material flow and workpieces with minimal preprocessing steps, often resulting in misalignment and subsequent rework or field failures.
Innovation Solution
The proposed alignment system utilizes microscopic native features of the workpiece to align tools, capturing images at multiple locations and using pattern recognition to determine positioning information, which is then used to correct for displacement, rotation, and distortion errors, enabling precise alignment without the need for additional alignment marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional alignment systems use deposited target alignment patterns, then alignment can be performed, but the process complexity increases and additional preprocessing steps are required
Solution Approach 1:
The workpiece's own native surface features serve as alignment references, eliminating the need for externally deposited alignment patterns. The imaging system captures and analyzes these inherent features directly, allowing the workpiece to align itself without additional preprocessing steps or external alignment markers.
Solution Approach 2:
The invention extracts and utilizes the naturally occurring native surface features from the workpiece itself, removing the need for artificial alignment patterns. By focusing on these inherent features through magnified imaging, the system separates the alignment function from the manufacturing process, achieving alignment without added complexity.
2Measurement precision
If alignment marks are added to workpieces, then alignment precision improves, but the manufacturing time and process steps increase
Solution Approach 1:
The workpiece provides its own alignment features through its native surface texture, eliminating the need for separate alignment mark deposition steps. This self-service approach maintains high manufacturing throughput while achieving precise alignment, as no additional time-consuming preprocessing or postprocessing steps are required.
3Measurement precision
If multiple imaging locations are used to capture workpiece features, then positioning accuracy improves, but the alignment system complexity increases
Solution Approach 1:
The alignment process is segmented into multiple imaging stages at different locations along the workpiece path. Each imaging unit captures features at its specific location, and the controller integrates these segmented measurements to compute comprehensive positioning information, achieving high accuracy without requiring a single complex imaging system.
Solution Approach 2:
The system adds the spatial dimension of multiple imaging locations along the workpiece conveyance path. By capturing images at different positions and times, the system creates a multi-dimensional dataset that enables accurate tracking of workpiece movement and positioning, transforming a single-point measurement into a distributed measurement network.
4Ease of manufacture
If native surface features are used for alignment, then additional alignment marks are eliminated, but the difficulty of detecting and measuring features increases
Solution Approach 1:
The imaging system changes the magnification parameter to enhance the visibility and detectability of native surface features. By magnifying the captured images, features that are naturally present but difficult to detect become clearly measurable, allowing the system to use inherent workpiece features for alignment without increasing manufacturing complexity.
Data Source
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AI summary
A method and system for alignment of a tool to a workpiece in a continuous or discontinuous material flow are disclosed. The workpiece may be a portion of a web of material. An imaging system captures first and second images of the workpiece at first and second occasions respectively. Microscopic native features of the workpiece are selected, detected, tracked and/or compared in the first and second images. Based on the correspondence between, tracking or relative displacement of features as captured in the first and second images, an alignment to the workpiece is controlled. In embodiments, the workpiece and a tool, a projected image or a pattern to be imparted to the workpiece by a lithography or photolithography apparatus are aligned based upon positioning information determined from an analysis of correlated features or texture in the images. Positioning information may include a positioning error or a distortion indication.