Optical Wafer Center Detection Using Fixed Light Guides
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Solution Overview
Problem
Existing substrate processing systems face challenges in accurately detecting the center of substrates due to variations in placement, recalibration needs, and limited adaptability to different substrate sizes, which can affect production yields and throughput.
Innovation Solution
The implementation of an optical sensor system using a light guide that generates an array of light beams within the chamber, allowing for precise detection of substrate position data by sensing the light beams as the substrate moves, thereby determining its center without the need for recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If emitters and sensors are positioned on movable portions of the chamber (such as a lid), then the system can be compact and easy to install, but movement of the emitter and sensor during operation creates recalibration needs that reduce throughput
Solution Approach 1:
The system divides the detection function into two separate components: a fixed light source/emitter mounted on the chamber body and a movable sensor mounted on the lid. This segmentation allows the light source to remain stationary (avoiding recalibration) while the sensor moves with the lid, resolving the contradiction between ease of installation and maintained throughput.
2Ease of manufacture
If the location and spacing of emitters and sensors are fixed based on a specific wafer size, then the system is simple to manufacture, but it limits the chamber to specific sizes of wafers
Solution Approach 1:
The system replaces fixed emitter-sensor spacing with a movable sensor that can be dynamically positioned at different locations along the lid. This allows the detection system to adapt to different wafer sizes while maintaining a simple fixed light source, resolving the contradiction between manufacturing simplicity and size versatility.
3Measurement precision
If an emitter and sensor are located in a lid and oriented in a vertically inclined orientation to scan an edge of a substrate, then the system can detect substrate edges, but it results in inaccuracy if the substrate is not horizontal
Solution Approach 1:
The system introduces a reflector as an intermediary component that redirects light from the fixed emitter to the movable sensor. This allows the detection system to measure substrate position without requiring the substrate to be perfectly horizontal, as the light path is defined by the fixed emitter and reflector geometry rather than by substrate orientation, resolving the contradiction between edge detection capability and measurement reliability.
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 enhances the accuracy and adaptability of substrate positioning, reduces downtime for recalibration, and allows for the processing of multiple substrate sizes without compromising precision, thereby improving overall production efficiency.
Implementation Method 1
a first light guide fixed relative to the light source and having a light input and a light output offset from the light input, the light input configured to receive light generated by the light source, wherein the first light guide guides the light between the light input and the light output so that the light output emits a light beam into the interior volume of the chamber
Implementation Method 2
a sensor configured to sense the light beam emitted from the light output
Data Source
AI summary
Methods, systems, and apparatus are provided for detecting a substrate in a chamber of a substrate processing system. In some embodiments, the system may include a sensor system comprising: a light source configured to generate light; a first light guide fixed relative to the light source and having a light input and a light output offset from the light input, the light input configured to receive light generated by the light source, wherein the first light guide guides the light between the light input and the light output so that the light output emits a light beam into a volume of the chamber; and a sensor configured to sense the light beam emitted from the light output.