Sensor Positioning for Semiconductor Substrate Accuracy
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Solution Overview
Problem
Existing semiconductor substrate processing systems face challenges in precisely and reliably positioning articles, such as semiconductor wafers or hard disks, within article fixtures due to potential false positive indications during loading, which can lead to inaccurate placement.
Innovation Solution
A method involving a sensor and an article fixture where the sensor is moved at two speeds to establish contact with a reference position, allowing the article to be adjusted by a predetermined increment to achieve precise positioning in a target location, thereby reducing false positives and ensuring consistent, accurate placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor moves at a constant speed to detect the reference position, then the positioning process is simple, but false positive indications occur leading to inaccurate placement
Solution Approach 1:
The sensor movement system transitions from constant speed to variable speed operation. The controller dynamically adjusts the sensor speed based on proximity to the reference position, using a first (slower) speed when near the reference position and a second (faster) speed when farther away. This dynamic speed adjustment eliminates false positive indications while maintaining positioning accuracy, resolving the contradiction between reliability and operational simplicity.
2Measurement precision
If the sensor moves slowly to avoid false positives, then positioning accuracy improves, but processing time increases
Solution Approach 1:
The sensor movement employs periodic speed variation based on proximity to the reference position. The controller implements a periodic control strategy where the sensor alternates between first speed (when within a threshold distance) and second speed (when beyond the threshold). This periodic action pattern ensures precise detection at critical moments while minimizing overall positioning time, resolving the contradiction between measurement precision and time efficiency.
3Productivity
If the article is positioned without preliminary sensor adjustment, then the process is faster, but false positive indications reduce reliability
Solution Approach 1:
The system performs preliminary sensor positioning action before final article placement. The controller first moves the sensor to detect the reference position with high precision using the first speed, establishes accurate positional reference, and only then proceeds with article positioning at higher speed. This preliminary action ensures reliability is established before productivity is maximized, resolving the contradiction between productivity and reliability.
Data Source
AI summary
A method includes moving a sensor and an article at a first speed to position the sensor into a reference position relative to an article fixture. The sensor and the article are moved at a second speed as the sensor approaches the reference position. It is determined when the sensor is in the reference position, wherein the sensor is configured to be in the reference position when a contact is established between the sensor and a surface of the article fixture. The article is moved by a predetermined increment relative to the reference position to position the article in a target position in response to determining that the sensor is in the reference position.