Wafer Backside Detection Using Diffuse Reflection
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Solution Overview
Problem
Conventional substrate processing apparatuses face erroneous detection of wafer presence or absence due to shifts in reflection angles caused by wafer deformation, misalignment, or finger deformation, leading to incorrect reception of specularly reflected light by the light receiver.
Innovation Solution
A substrate processing apparatus with a holding structure and a light detector system that emits light towards the substrate's back surface, where the light receiver is positioned to receive diffusely reflected light without receiving specularly reflected light, and a controller determines the substrate's presence based on the light receiving state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the light receiver is arranged to receive specularly reflected light for wafer detection, then the detection method is simple, but erroneous detection occurs when the wafer is deformed, misaligned, or when the fingers are deformed
Solution Approach 1:
The patent changes the detection parameter from receiving specularly reflected light to receiving diffusely reflected light. The light receiver is arranged to receive diffusely reflected light from the wafer surface while avoiding specularly reflected light, thereby maintaining detection simplicity while improving reliability against wafer deformation and misalignment
Solution Approach 2:
The patent converts the harmful effect of specular reflection (which causes erroneous detection when reflection angle shifts) into a beneficial configuration by positioning the light receiver to specifically avoid the specular reflection path while capturing diffuse reflection, thus turning the reflection phenomenon itself into a reliable detection method
2Illumination intensity
If the light receiver receives any reflected light including specularly reflected light, then the light receiving state is strong, but erroneous detection occurs due to reflection angle shifts
Solution Approach 1:
The patent applies local quality by selectively receiving only diffusely reflected light while excluding specularly reflected light. The light receiver is positioned and configured to capture light from specific regions (diffuse reflection paths) while ignoring other regions (specular reflection paths), thereby maintaining sufficient light intensity while improving detection precision
Solution Approach 2:
The patent segments the reflected light into two distinct components: specularly reflected light (which is excluded) and diffusely reflected light (which is received). By separating these light components spatially and selectively receiving only the diffuse component, the system maintains adequate light intensity while eliminating erroneous detection
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 configuration effectively suppresses erroneous detection of the substrate by ensuring the light receiver only receives diffusely reflected light, improving the accuracy of wafer detection and enhancing production efficiency.
Implementation Method 1
a light receiver arranged to be capable of receiving a diffusely reflected light of the irradiation light irradiated from the light emitter without receiving a specularly reflected light of the irradiation light
Data Source
AI summary
According to the present disclosure, there is provided a technique capable of suppressing an erroneous detection of a presence or absence of a substrate caused by a light receiver receiving a specularly reflected light. There is provided a technique that includes: a holding structure provided with a placing surface capable of accommodating a substrate thereon; a light detector including: a light emitter arranged to irradiate an irradiation light toward a back surface of the substrate placed on the placing surface; and a light receiver arranged to be capable of receiving a diffusely reflected light of the irradiation light irradiated from the light emitter without receiving a specularly reflected light of the irradiation light; and a controller configured to be capable of determining a presence or absence of the substrate based on a light receiving state of the light receiver.