Reflector Element Illumination for FOUP Interior Inspection

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Solution Overview

Problem

There is a need for an efficient method to inspect substrate containers, such as front opening unified pods (FOUPs), for damage, dimensional conformity, and contamination, as existing systems are inadequate in identifying and removing defective or non-conforming containers that can cause wafer damage and contamination during semiconductor processing.

Innovation Solution

The method employs reflector elements within the container to provide effective illumination of interior surfaces using diffuse reflection, allowing cameras to generate images that can be analyzed for damage, dimensional accuracy, and contamination, using line scan or area scan cameras and adjustable reflector elements to optimize illumination and viewing angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light source is positioned outside the container to illuminate interior surfaces, then the illumination coverage is limited and shadows are cast on textured surfaces, but the system complexity is reduced

Engineering Contradiction:

Improveillumination of interior surfacesVSAvoidsystem complexity

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The reflector element is positioned inside the container body, nested within the inspection system structure. This internal placement allows the reflector to utilize the container's own geometry and brings the illumination function directly to the interior surfaces, eliminating shadows cast by external lighting while maintaining system compactness

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The reflector element acts as an intermediary between the light source and the interior surfaces. It receives light from the source and redirects it through diffuse reflection to illuminate textured surfaces uniformly, preventing shadow formation while the system remains relatively simple in structure

Inventive Principle:

Principle #24Intermediary (Mediator)

2Area of stationary object

If the light source is moved to illuminate all regions of interest, then complete coverage is achieved, but the inspection time and system complexity increase

Engineering Contradiction:

Improvecoverage of interior surfacesVSAvoidinspection time

Core Design Contradiction:

Area of stationary objectVSLoss of time

Solution Approach 1:

The reflector element provides continuous illumination across all interior surfaces simultaneously through diffuse reflection. This eliminates the need for sequential scanning or moving the light source to different positions, achieving complete area coverage while maintaining constant inspection time and reducing system complexity

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The reflector element changes the parameters of light propagation by converting direct light into diffuse reflection. This parameter change allows a single stationary light source to illuminate the entire interior surface area uniformly, achieving complete coverage without requiring multiple light sources or movement mechanisms

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If direct lighting is used on textured surfaces, then the setup is simple, but shadows are cast that obscure defect detection

Engineering Contradiction:

Improveillumination setup simplicityVSAvoiddefect detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The reflector element converts the potentially harmful effect of direct lighting (which creates shadows on textured surfaces) into a beneficial diffuse reflection. This transforms the lighting behavior to eliminate shadows while maintaining ease of setup, thereby improving defect detection accuracy without sacrificing manufacturing simplicity

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 approach enables thorough and efficient evaluation of container states, preventing wafer mishandling and contamination by identifying defects and non-conformities, ensuring secure and clean storage conditions for substrates.

Implementation Method 1

the light from the light source is reflected by the reflector element in a diffuse manner. Such a diffuse reflection of light leads to an homogeneous illumination of interior surfaces of the container body

Methodology Applied

Scientific EffectDiffuse reflection: Reflection

Data Source

PatentUS11569107B2Method for inspecting a container and inspection system

Publication Date: 2023.01.31 BROOKS AUTOMATION US LLC

AI summary

The present disclosure relates to a method for inspecting a container body adapted and configured to hold substrates, comprising the steps of directing light from a light source onto a reflector element positioned within an interior space of the container body, such that the light is reflected to illuminate at least one interior surface of the container body, wherein the light is reflected by the reflector element in a diffuse manner and generating at least one image of the at least one interior surface by means of at least one camera, and evaluating the state of the container body on the basis of the at least one image.