Dual-Stage Wafer Chuck for Flatness at High Rotation Speed
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Solution Overview
Problem
Existing optical inspection devices face challenges in maintaining sample flatness during high-speed rotation, leading to potential undulation and reduced inspection accuracy due to centrifugal forces, especially in miniaturized semiconductor manufacturing where higher sensitivity and shallow focal depth are required.
Innovation Solution
A sample stage design featuring an outer circumference stage with a first adsorption surface and a pressure receiving chamber, along with an inner circumference stage housed within, and pneumatic channels for loading and unloading samples, ensuring stable adhesion and support during high-speed rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sample stage rotates at high speed during inspection, then the inspection time is shortened and productivity is improved, but centrifugal force causes undulation of the sample outer circumference and flatness deteriorates
Solution Approach 1:
The sample stage is divided into two independent adsorption surfaces: a first adsorption surface for the outer circumference and a second adsorption surface for the inner circumference. This segmentation allows each surface to independently control and maintain adsorption pressure on different regions of the sample, preventing undulation caused by centrifugal force during high-speed rotation while maintaining productivity.
2Ease of operation
If a fork-shaped arm with two claws supports the outer edge of the sample, then the sample can be transferred without interference from the sample stage, but the outside diameter of the sample stage must be smaller than the distance between the claws, preventing adsorption of the outer circumference
Solution Approach 1:
The invention adds a vertical dimension to the adsorption system by providing a second adsorption surface that can project upward from the first adsorption surface. This allows the sample stage to adsorb the outer circumference of the sample through the first adsorption surface while maintaining clearance for the transfer arm, resolving the spatial conflict between transfer arm clearance and adsorption area.
3Strength
If the outer circumference stage has a large adsorption area, then the sample outer circumference can be firmly adsorbed, but the transfer arm cannot move freely for loading and unloading operations
Solution Approach 1:
The second adsorption surface is designed to be movable relative to the first adsorption surface, capable of projecting upward and retracting. During transfer operations, the second adsorption surface retracts to provide clearance for the transfer arm. During inspection, it projects upward to provide additional adsorption force on the outer circumference, dynamically adapting to different operational requirements.
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
Improves sample flatness and increases inspection sensitivity by maintaining sample stability during high-speed rotation, enhancing the accuracy of defect detection in semiconductor wafers.
Implementation Method 1
a first adsorption surface... a second adsorption surface... adsorbs and holds a sample
Data Source
AI summary
In this sample stage that adsorbs and holds a sample, the configuration includes: an outer circumference stage that has a first adsorption surface and a pressure receiving chamber that is a recess formed in the center thereof; an inner circumference stage that has a second adsorption surface, and that is housed in the pressure receiving chamber and can project upward from the outer circumference stage; a first flow channel for a sample desorption operation that is formed on the outer circumference stage and is opened on the first adsorption surface; a second flow channel for the sample desorption operation that is formed on the outer circumference stage and the inner circumference stage and is opened on the second adsorption surface; and a third flow channel for inner circumference stage elevating driving that is formed on the outer circumference stage and is opened in the pressure receiving chamber.