Reticle ROI Processing to Reduce False Particle Detections
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Solution Overview
Problem
Lithographic patterning devices suffer from contamination and false positive particle detections, leading to inaccuracies and inefficiencies in the patterning process, which can result in device failure and increased costs.
Innovation Solution
An inspection system is developed with a radiation source that irradiates multiple surfaces of an object, using apodized apertures and structured light patterns to minimize false positives and accurately detect particle contamination, incorporating electro-optical and opto-mechanical modules for beam control and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional particle detection methods are used, then detection coverage is maintained, but false positive detections increase leading to reduced reliability
Solution Approach 1:
The inspection system divides the reticle surface into multiple regions of interest (ROIs) that are illuminated and inspected separately. This segmentation allows the system to distinguish between particles and pattern reflections by isolating specific areas for detection, thereby reducing false positives while maintaining comprehensive coverage
Solution Approach 2:
Different regions of the reticle are illuminated with different characteristics - pattern regions receive illumination that produces reflections, while ROI regions are illuminated to highlight particles. This local differentiation enables the system to accurately distinguish between legitimate pattern features and actual contaminants
2Productivity
If entire reticle surfaces are inspected simultaneously, then inspection time is reduced, but detection precision deteriorates due to increased false positives
Solution Approach 1:
The reticle is divided into multiple ROIs that can be inspected in parallel or sequence. This allows the system to maintain high throughput by processing multiple regions simultaneously while achieving high precision in each region through dedicated illumination and detection
Solution Approach 2:
The inspection system uses periodic illumination patterns where different regions are illuminated in alternating cycles. This periodic action enables comprehensive inspection of the entire reticle surface while maintaining the ability to distinguish particles from pattern reflections through temporal separation
3Measurement precision
If pattern regions are illuminated during inspection, then detection coverage is improved, but false positive detections increase due to reflected light
Solution Approach 1:
The inspection system separates pattern regions from ROI regions spatially and illuminates them differently. Pattern regions receive illumination that produces reflections for detection, while ROI regions receive particle-highlighting illumination. This segmentation eliminates the harmful reflections from pattern regions that would otherwise interfere with particle detection
Solution Approach 2:
The system uses specific illumination characteristics as intermediaries to distinguish between pattern reflections and particle scattering. By controlling the illumination angle, wavelength, and intensity, the system creates optical conditions where particles scatter light while pattern reflections are suppressed or differentiated
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system reduces false positive detections and enhances the accuracy of particle detection, improving the reliability and efficiency of the lithographic process by minimizing contamination-related errors.
Implementation Method 1
a radiation source that generates a beam of radiation to irradiate a first surface of an object
Implementation Method 2
receives radiation scattered from the region of the first surface
Data Source
AI summary
An inspection system includes a radiation source that generates a beam of radiation and irradiates a first surface of an object, defining a region of the first surface of the object. The radiation source also irradiates a second surface of the object, defining a region of the second surface, wherein the second surface is at a different depth level within the object than the first surface. The inspection system may also include a detector that defines a field of view (FOV) of the first surface including the region of the first surface, and receives radiation scattered from the region of the first surface and the region of the second surface. The inspection system may also include a processor that discards image data not received from the region of the first surface, and constructs a composite image comprising the image data from across the region of the first surface.