Semiconductor Substrate Position Detection Using Single Camera
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for detecting the position of a disc-shaped substrate in semiconductor manufacturing require equipment within the transport chamber, increasing chamber size and reducing throughput, and involve high costs due to the need for multiple cameras and large viewports, which also compromise the vacuum environment.
Innovation Solution
A position detecting device using a single imaging camera to capture the periphery of the substrate, with an edge extraction section and coordinate detection section to calculate the center position, allowing for precise detection without the need for multiple cameras or large viewports, thereby maintaining the vacuum environment and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotatable pedestal and line sensor are installed in the transport chamber to detect substrate position, then detection capability is improved, but the chamber size increases and throughput decreases
Solution Approach 1:
The detection function is extracted from the transport chamber environment and relocated to the external imaging system. The patent uses cameras and light sources positioned outside the vacuum chamber to capture substrate images through viewports, eliminating the need for internal detection equipment like rotatable pedestals and line sensors.
Solution Approach 2:
A transparent viewport serves as an intermediary between the vacuum-sealed transport chamber and the external imaging system. This allows optical signals to pass through while maintaining vacuum integrity, enabling non-contact position detection without compromising the chamber environment.
2Measurement precision
If multiple cameras and large viewports are used to capture the entire substrate periphery, then detection coverage is improved, but costs increase and vacuum environment is compromised
Solution Approach 1:
The substrate detection task is segmented into capturing only the necessary peripheral features rather than the entire substrate. The patent detects position information from localized edge features or notches on the substrate periphery, eliminating the need for multiple cameras to capture the full substrate area.
Solution Approach 2:
The patent applies partial action by capturing only the essential peripheral portion of the substrate that contains position information, rather than imaging the entire substrate. This reduces the number of cameras and viewports needed while maintaining sufficient detection accuracy.
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
Enables precise detection of the substrate's center position using a single camera, increasing detection precision and reducing costs by eliminating the need for high-resolution cameras and large viewports, while maintaining the vacuum environment within the transport chamber.
Implementation Method 1
a plurality of cameras are located on the upper surface outside the transport chamber and a light source is located on the undersurface outside the transport chamber opposing the cameras
Implementation Method 2
The cameras are positioned so as to pick up images of the peripheral part of the semiconductor wafer being transported in the transport chamber
Data Source
AI summary
Provided is a position detecting device that is capable of precisely detecting the coordinates of the center of a disc-shaped substrate from image data captured by one camera, calculating the amount of positional misalignment of the disc-shaped substrate on a support member as the disc-shaped substrate is being transported during processing, and correcting the position such that the substrate can be located at the precise loading position. Isosceles right triangles, each having the radius of the disc-shaped substrate as one side, are generated from the coordinates of two places on edge data extracted from the image data and the radius on the edge data, and the coordinates of the center position of the disc-shaped substrate are detected by using the Pythagorean theorem.