Topology-Preserved Reference Rendering for Beam Inspection Alignment
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Solution Overview
Problem
Existing die-to-database alignment techniques face challenges in achieving high precision and repeatability for aligning features in complex semiconductor structures due to high variance and poor repeatability, particularly in devices like DRAM and FinFETs, where edge placement error (EPE) needs to be within 0.5 nm or less.
Innovation Solution
An image alignment method that modifies rendered reference images by preserving their topology through blurring or downsampling based on specific characteristics, allowing for precise alignment of inspection images with reference images, thereby improving alignment precision and reducing EPE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing die-to-database alignment techniques (edge-based and correlation-based) are used, then high throughput is achieved, but alignment precision and repeatability deteriorate due to high variance and poor repeatability in complex device structures
Solution Approach 1:
The patent creates a modified rendered image that copies the topological structure of the reference image while adapting it to match the inspection image characteristics. This modified copy serves as an intermediate reference that maintains the benefits of database alignment while improving precision by preserving topological relationships rather than relying on edge detection or correlation methods that fail in complex structures
Solution Approach 2:
The patent transforms the reference image into a modified rendered image by changing rendering parameters to preserve topology. This parameter transformation allows the reference image to be adapted to different inspection conditions while maintaining its structural integrity, thereby improving alignment precision without sacrificing throughput
2Productivity
If existing die-to-database alignment techniques are used, then high throughput is achieved, but repeatability deteriorates due to poor repeatability in complex device structures
Solution Approach 1:
The modified rendered image acts as a reliable copy that preserves topological relationships, providing a consistent reference for alignment across multiple inspections. This topological copying ensures repeatability by maintaining structural relationships that are invariant to variations in inspection conditions, unlike edge-based or correlation-based methods
3Measurement precision
If topology is preserved during rendering modification, then alignment precision improves, but image modification complexity increases
Solution Approach 1:
The patent applies systematic parameter changes to the rendering process to preserve topology. By modifying rendering parameters rather than manually adjusting image features, the method achieves precise alignment while keeping the modification process automated and manageable, reducing the effective complexity despite the sophisticated topological preservation requirements
Data Source
AI summary
Systems and methods of image alignment are disclosed herein. The method of image alignment may comprise obtaining an image of a sample, obtaining information associated with a corresponding reference image, generating a modified rendered image by blurring a rendered image of the corresponding reference image such that a topology of the rendered image is substantially preserved, wherein a degree of blurring is based on a characteristic of the topology, and aligning the image of the sample with the blurred rendered image. The method may further comprise aligning the image of the sample with the corresponding reference image based on an alignment between the image of the sample and the blurred rendered image.