Rectifying Plate Airflow Control for Substrate Cleanliness
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Solution Overview
Problem
Existing examination devices face challenges in preventing foreign matter adhesion to substrates due to turbulent airflow, which is exacerbated by the dominant rotating airflow in inspection units, leading to contamination risks.
Innovation Solution
The implementation of a rectifying plate that guides clean airflow downward around the substrate by blocking airflow toward the substrate, using a configuration with specific angles and openings to manage airflow and prevent turbulence, ensuring clean air movement without recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clean air is supplied to the inspection chamber using fan filter units, then the substrate can be inspected, but turbulent airflow generates foreign matter adhesion to the substrate
Solution Approach 1:
The airflow control system is divided into multiple independent components: a gas supply unit for introducing clean air, a suction unit for removing air, and an airflow guide for directing flow paths. This segmentation allows independent optimization of each function to achieve laminar flow while maintaining substrate cleanliness.
Solution Approach 2:
An airflow guide is introduced as an intermediary component between the gas supply unit and the substrate. This mediator directs the airflow in a controlled manner, preventing direct turbulent flow from reaching the substrate while still maintaining effective air circulation for inspection.
2Productivity
If the stage rotates at high speed to enable inspection, then inspection efficiency improves, but rotating airflow dominates and increases foreign matter hoisting
Solution Approach 1:
The suction unit creates a counteracting force to balance the dominant rotating airflow generated by high-speed stage rotation. By introducing a controlled suction force, the system offsets the harmful hoisting effect of turbulent rotating air while preserving the high-speed rotation needed for efficient inspection.
Solution Approach 2:
The system uses pneumatic control through the suction unit to manage airflow dynamics. By controlling air pressure and flow rates, the system can suppress foreign matter hoisting caused by high-speed rotation without reducing the rotational speed necessary for inspection productivity.
3Ease of operation
If airflow is guided to exhaust port using exhaust fan unit, then air circulation is established, but airflow may return onto the substrate increasing contamination risk
Solution Approach 1:
The airflow guide is positioned in advance to pre-direct the airflow path before it can reach the substrate. This preliminary action ensures that air flow is channeled away from the substrate area, preventing contamination while maintaining effective air circulation for inspection.
Solution Approach 2:
The airflow guide introduces a vertical component to airflow control by directing air flow both horizontally toward the exhaust port and vertically away from the substrate. This multi-dimensional flow control prevents air from returning onto the substrate while maintaining circulation efficiency.
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 suppresses the likelihood of foreign matter adhesion by ensuring clean air moves downward, maintaining substrate cleanliness and reducing contamination risks during inspections.
Implementation Method 1
guides an airflow from a gas supply unit downward from the outer peripheral portion of the stage, and is disposed between the gas supply unit and the stage to block an airflow toward the substrate
Data Source
AI summary
The purpose of the present invention is to allow a clean airflow around a substrate to reliably move downward of the substrate in an examination device in which clean air is supplied to an inspection chamber. This examination device is provided with a rectifying plate (see FIG. 4A) which covers a part of the upper surface of a stage for mounting a substrate, and is disposed between a gas supply unit and the stage to block an airflow toward the substrate.