Flat Panel Contamination Detection Using Beam Trimming
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Solution Overview
Problem
Existing apparatuses for detecting particulate contamination on flat panels suffer from crosstalk issues due to mirrored particles and pattern reflections, leading to degraded signal-to-noise ratio and inaccurate detection, especially when the angle of collection is close to the angle of reflection, which complicates system alignment and compatibility.
Innovation Solution
An apparatus with a beam trimmer, comprising a reflecting prism or optical members, separates scattered radiation from reflected radiation, ensuring the reflected radiation does not reach the detector, and the detector's radiation collection surface is perpendicular to the flat panel, improving adaptability and detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dark-field scattering technique is used for contamination detection, then the detection capability is provided, but crosstalk from mirrored particles and pattern reflections degrades the signal-to-noise ratio
Solution Approach 1:
The patent segments the radiation detection by using multiple detectors positioned at different angles. The first detector collects scattered radiation at a first angle, while the second detector collects scattered radiation at a second angle. This angular segmentation allows the system to distinguish between scattered radiation from contaminants and reflected radiation from the substrate, thereby reducing crosstalk and improving detection accuracy.
Solution Approach 2:
The patent introduces an intermediary approach by using angle-selective detection. Instead of directly measuring all scattered radiation, the system uses multiple detectors at specific angles to selectively measure scattered radiation components. This intermediary angular selection filters out the harmful reflected radiation component that would otherwise contaminate the measurement signal.
2Measurement precision
If the angle of collection is set close to the angle of reflection to improve detection sensitivity, then the detection capability is enhanced, but reflected radiation overlaps with the field of view and intensifies scattered radiation leading to inaccurate determination
Solution Approach 1:
The patent divides the detection into multiple angular segments using separate detectors. By positioning detectors at specific angles that avoid the reflection angle, the system can collect scattered radiation without contamination from reflected radiation. This angular segmentation resolves the contradiction by allowing sensitive detection while excluding the harmful reflected component through geometric separation.
3Measurement precision
If the optical axis of the imaging module must be aligned with the angle of collection, then the detection geometry is constrained, but system alignment complexity increases and compatibility decreases
Solution Approach 1:
The patent employs a universal detection geometry where multiple detectors can be positioned at different angles relative to a common illumination source. This multi-functional arrangement allows the same basic optical configuration to achieve detection at various angles without requiring complex realignment of the entire optical system, thereby reducing alignment complexity while maintaining detection precision.
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
This solution effectively separates reflected radiation from scattered radiation, enhancing detection accuracy and adaptability to different system configurations, thereby improving the signal-to-noise ratio and ensuring accurate detection of particulate contamination without requiring adjustments in system alignment.
Implementation Method 1
a radiation beam scattered by contaminants on a surface of a flat panel under test and resulting in a scattered radiation
Implementation Method 2
a radiation beam reflected by a surface of a flat panel under test and resulting in a reflected radiation
Data Source
AI summary
An apparatus for detecting a degree of particulate contamination on a flat panel is disclosed, including: an illuminator for producing a radiation beam which results in scattered radiation from its scattering by contaminants on a surface of the flat panel under test and reflected radiation from its reflection by the surface of the flat panel under test; a detector for collecting the scattered radiation, the detector having a radiation collection surface perpendicular to a normal of the surface of the flat panel under test; and a beam trimmer for separating the reflected radiation from the scattered radiation, the beam trimmer including a first optical member, disposed in correspondence with the scattered radiation and configured for directing the scattered radiation to be collected by the detector, and a second optical member disposed in correspondence with the reflected radiation and configured for directing the reflected radiation not to be collected by the detector.