Substrate Transfer Arm Rotation Angle Compensation
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Solution Overview
Problem
Conventional substrate processing systems face challenges in accurately mounting substrates at a desired rotation angle due to thermal expansion and displacement changes, leading to misalignment issues during high-temperature processes.
Innovation Solution
A method and system that calculates and adjusts the rotation angle of the substrate with respect to the gripping part of the transfer arm before transfer, using sensors and thermal expansion calculations to ensure precise alignment at the transfer destination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-link type transfer arm is used to improve heat resistance, then the transfer arm can withstand high temperatures without bearings and driving belts, but the substrate may be rotated in excess of a predetermined rotation angle due to thermal expansion and displacement changes
Solution Approach 1:
The system performs preliminary calculation of thermal expansion and displacement changes before the transfer operation. The rotation angle of the substrate with respect to the gripping part is adjusted in advance based on predicted misalignment, so that when thermal expansion occurs during transfer, the substrate arrives at the transfer destination with the correct rotation angle.
Solution Approach 2:
The system calculates the misalignment of the substrate in the rotational direction at the transfer destination based on thermal expansion characteristics and displacement changes. This feedback information is used to adjust the rotation angle of the substrate with respect to the gripping part, creating a closed-loop control system that compensates for thermal effects.
2Measurement precision
If the extension amount of the transfer arm is changed to compensate for thermal expansion, then the substrate transfer distance is corrected, but the substrate rotation angle becomes excessive causing mounting errors
Solution Approach 1:
The system calculates the required rotation angle adjustment before the transfer operation based on expected thermal expansion. By pre-adjusting the substrate rotation angle with respect to the gripping part, the system ensures that when the transfer arm extends due to thermal expansion, the substrate arrives at the correct rotation angle without excessive rotation.
Solution Approach 2:
The system changes the rotation angle parameter of the substrate with respect to the gripping part based on calculated misalignment. This parameter adjustment compensates for the effects of thermal expansion and displacement changes, maintaining accurate rotation angle control despite changes in transfer arm extension.
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 approach effectively prevents rotational misalignment, allowing for accurate mounting of substrates at the desired rotation angle, simplifying the system configuration and maintaining throughput by eliminating the need for additional rotation mechanisms.
Implementation Method 1
it may be necessary to change a transfer amount of the wafer, namely an extension amount of the transfer arm, which may cause a problem in which the wafer cannot be accurately mounted on a mounting table at a desired rotation angle
Data Source
AI summary
Provided is a substrate transferring method which is capable of accurately mounting a substrate at a desired rotation angle. In order to eliminate a misalignment of a wafer W in a rotational direction in a vacuum process chamber, which is caused by a variation in a transfer distance of the wafer W, the wafer W is mounted on a stage while being offset from the center of the stage in a load lock chamber and an angle of rotation of the wafer W with respect to a fork when a transfer arm receives the wafer W is changed.