Reticle Repeater Defect Detection in EUV Lithography
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Solution Overview
Problem
Current repeater defect detection methods in semiconductor manufacturing are limited by high defect density and sensitivity issues, particularly in extreme ultraviolet (EUV) lithography, where existing systems cannot maintain high sensitivity due to overwhelming data pipelines and noise, leading to missed weak repeater defects.
Innovation Solution
The system moves repeater detection into the front end of the inspection process, using an inspection subsystem to generate images of wafers and computer subsystems to compare test images with reference images, identifying repeater defects by detecting defects in multiple images and applying hot thresholds to enhance sensitivity and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hot defect detection is performed to find weak repeater defects, then the sensitivity for detecting weak repeater defects is improved, but the data pipeline becomes overwhelmed and the system capacity for storing defects is exceeded
Solution Approach 1:
The inspection process is segmented into multiple stages: initial defect detection, repeater candidate identification, and final defect confirmation. By dividing the workflow into these segments, the system can process defects in manageable batches rather than attempting to store all possible defects simultaneously, thus reducing data pipeline capacity requirements while maintaining high sensitivity for weak repeater defects.
Solution Approach 2:
The system performs preliminary actions by pre-identifying repeater defect candidates before final defect confirmation. This preliminary screening allows the system to filter and prioritize defects that are likely to be repeaters, reducing the overall data volume that needs to be stored and processed in subsequent stages while maintaining the ability to detect weak repeater defects.
2Productivity
If a location filter is applied to eliminate non-repeater events, then the number of defects to process is reduced, but weak repeater defects are lost because the inspection cannot be run hot enough
Solution Approach 1:
The system performs preliminary repeater candidate identification by analyzing defect patterns and locations before applying the final location filter. This preliminary action allows weak repeater defects to be identified and preserved, as they can be distinguished from non-repeater events through their pattern recognition, thereby avoiding their loss during the filtering process.
Solution Approach 2:
The system implements feedback mechanisms that continuously monitor defect patterns and adjust the filtering criteria accordingly. By analyzing the distribution and patterns of detected defects, the system can refine its filtering algorithms to preserve weak repeater defects while still eliminating non-repeater events, thus maintaining both productivity and detection precision.
3Ease of manufacture
If repeater detection is performed as a post-processing operation, then the inspection tool can use existing defect detection capabilities, but the repeater detection cannot be performed concurrently with defect detection and reduces overall inspection throughput
Solution Approach 1:
The system merges repeater detection with the primary defect detection operation by integrating repeater analysis into the same inspection workflow. This merging allows both defect detection and repeater identification to be performed concurrently, utilizing existing inspection capabilities while maintaining high throughput, as the repeater detection is conducted in parallel rather than as a separate post-processing step.
Solution Approach 2:
The inspection tool is enhanced with multi-functionality to perform both defect detection and repeater identification using the same hardware and software framework. This universality allows the system to leverage existing inspection capabilities while adding repeater detection functionality, thereby avoiding the need for separate dedicated equipment and maintaining high inspection throughput.
Data Source
AI summary
Systems and methods for detecting defects on a reticle are provided. One system includes computer subsystem(s) configured for performing at least one repeater defect detection step in front-end processing during an inspection process performed on a wafer having features printed in a lithography process using a reticle. The at least one repeater defect detection step performed in the front-end processing includes identifying any defects detected at corresponding locations in two or more test images by double detection and any defects detected by stacked defect detection as first repeater defect candidates. One or more additional repeater defect detections may be performed on the first repeater defect candidates to generate final repeater defect candidates and identify defects on the reticle from the final repeater defect candidates.