Foreign Substance Inspection Apparatus Edge Exclusion
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Solution Overview
Problem
Existing foreign substance inspection apparatuses face signal saturation issues in optical receivers due to strong light reflections from substrate edges, leading to inefficient detection and potential damage to the equipment.
Innovation Solution
A foreign substance inspection apparatus that employs a controller to exclude regions with steps on the substrate from detection, preventing light projection onto these areas to avoid signal saturation, using a projector and optical receiver with digital signal processing to detect foreign substances efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light is projected onto the entire surface including edges to perform comprehensive foreign substance inspection, then detection coverage is improved, but signal saturation occurs in the optical receiver due to strong light reflection from substrate edges
Solution Approach 1:
The substrate surface is divided into two distinct regions: a first region (edge area with steps) and a second region (central area without steps). The controller selectively projects light only onto the second region, excluding the first region from detection. This segmentation allows comprehensive inspection of the detectable area while avoiding signal saturation from edge reflections.
Solution Approach 2:
Different regions of the substrate are treated differently regarding light projection. The first region (edge) is excluded from light projection to prevent saturation, while the second region (center) receives light for detection. This local differentiation optimizes both detection accuracy and coverage by adapting the inspection approach to the specific characteristics of each region.
2Productivity
If light is continuously projected during scanning to maintain detection efficiency, then productivity is improved, but the optical receiver may be damaged by excessive anode current when strong reflected light enters
Solution Approach 1:
The controller pre-identifies the first region (edge area with steps) before light projection begins and configures the system to exclude this region from light projection. By performing this exclusion action in advance, the system maintains continuous light projection during scanning (preserving productivity) while preventing excessive current that would damage the optical receiver.
Solution Approach 2:
The strong light reflection from substrate edges, which normally causes signal saturation and potential damage, is converted into a beneficial exclusion criterion. The controller uses the presence of steps at the edges as a basis for excluding these regions from light projection, thereby transforming a harmful effect into a protective mechanism that preserves optical receiver reliability.
3Area of stationary object
If the inspection apparatus inspects the entire surface including edges like the prior art, then comprehensive coverage is achieved, but the system becomes inefficient by not executing detection during half of the scanning period
Solution Approach 1:
The light projection is made dynamic and adaptive rather than static and continuous. The controller dynamically adjusts light projection based on the scanning position, enabling detection during the entire scanning period over the second region while excluding the first region. This dynamic approach eliminates the inefficiency of halting detection during portions of the scan cycle.
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 solution enables efficient foreign substance detection while preventing signal saturation and potential damage to the optical receiver, allowing for accurate detection on a wider surface area without compromising equipment integrity.
Implementation Method 1
A foreign substance inspection apparatus will detect a foreign substance by irradiating a substrate with oblique incident light and causing an optical receiver to receive the scattered light from the foreign substance
Implementation Method 2
In a photomultiplier tube, after electrons generated in a photocathode by the light incidence are accelerated by a high voltage, the electrons are made to collide with a plurality of stages of dynodes which are configured to generate secondary electrons
Data Source
AI summary
A foreign substance inspection apparatus performs foreign substance detection processing of detecting a foreign substance present on a surface of a substrate. The apparatus includes a detector that includes a projector configured to project light onto the surface and an optical receiver configured to receive scattered light from the surface, a scanning mechanism configured to scan a position on the surface onto which the light is projected by the projector, and a controller configured to control the foreign substance detection processing so that detection of the foreign substance is performed on a detection region which is a region excluding, from the surface, an exclusion region where a step is present thereon, wherein the controller controls the projection by the projector so that light is not projected to the step.