Frog-leg Transfer Mechanism Thermal Expansion Correction
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Solution Overview
Problem
Conventional substrate processing techniques face challenges in achieving high accuracy in transferring substrates to processing modules due to thermal expansion of multi-joint arms, particularly in frog-leg type double-arm mechanisms, which complicates positioning and correction of substrate transfer positions.
Innovation Solution
A substrate processing apparatus with a frog-leg type substrate transfer mechanism featuring bilaterally symmetric link mechanisms, including driving and driven arms, uses a rotation angle measuring part and holding body detection to acquire and correct the rotation angle of the driving arms, employing a moving average calculation to ensure accurate positioning by comparing measured angles with reference values, thus compensating for thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a frog-leg type double-arm transfer mechanism is used for substrate transfer, then the structural complexity is reduced and weight is decreased compared to single-arm mechanisms, but thermal expansion causes positioning accuracy to deteriorate
Solution Approach 1:
The patent applies asymmetry by introducing different correction approaches for each arm of the symmetric mechanism. Although the frog-leg type mechanism has bilaterally symmetric link mechanisms, the correction amounts for rotation angles are determined independently for each arm based on their respective thermal expansion characteristics, creating an asymmetric correction strategy that accounts for potential differences in thermal behavior between arms
Solution Approach 2:
The patent changes the parameter of rotation angle correction amounts based on temperature. By measuring the temperature of each arm and calculating correction amounts according to thermal expansion coefficients and temperature differences, the system dynamically adjusts the rotation angle parameters to compensate for thermal expansion effects, thereby maintaining positioning accuracy despite temperature variations
2Weight of moving object
If aluminum material is used for the arm to reduce weight and increase versatility, then the weight is decreased, but the coefficient of thermal expansion increases causing positioning to deteriorate
Solution Approach 1:
The patent implements feedback by measuring the temperature of each arm using temperature sensors and using this information to calculate and apply correction amounts to the rotation angles. This closed-loop feedback mechanism continuously monitors thermal conditions and adjusts positioning parameters accordingly, compensating for the high thermal expansion coefficient of aluminum material
Solution Approach 2:
The patent changes the rotation angle parameters based on temperature measurements and thermal expansion calculations. By dynamically adjusting the rotation angle correction amounts according to the actual temperature conditions and the known thermal expansion coefficient of aluminum, the system maintains positioning accuracy despite using lightweight aluminum material with high thermal expansion
3Manufacturing precision
If position deviation correction is performed using one-arm type multi-joint arm, then positioning accuracy is improved, but the device complexity increases and the symmetric frog-leg type mechanism cannot be utilized
Solution Approach 1:
The patent applies segmentation by dividing the correction process into independent segments for each arm of the frog-leg mechanism. Instead of using a single centralized correction system, the patent calculates and applies correction amounts independently for the left and right arms based on their respective temperature measurements and thermal expansion characteristics, allowing the symmetric mechanism to maintain its structural advantages while achieving accurate positioning
4Manufacturing precision
If thermal expansion correction is applied to frog-leg type double-arm mechanism, then positioning accuracy is improved, but the system complexity increases due to additional measurement and calculation requirements
Solution Approach 1:
The patent applies partial action by focusing correction efforts on the critical parameter of rotation angle rather than attempting to correct all possible positioning deviations. By calculating and applying correction amounts specifically for the rotation angles of the driving arms based on temperature measurements, the system achieves effective positioning correction without implementing overly complex comprehensive correction systems for all degrees of freedom
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 enables high-accuracy substrate transfer by accounting for thermal expansion, reducing positional bias and improving reliability in correcting the transfer position, even in the initial stages of operation.
Implementation Method 1
the coefficient of thermal expansion is larger than that of the holding member made of ceramic or the like. Therefore, it is regarded that it is important to consider elongation or strain of the arm for the positioning
Implementation Method 2
a moving average of a preset sampling number for the measurement value of the rotation angle based on time series data of the measurement value of the rotation angle acquired in the step of acquiring the measurement value
Data Source
AI summary
A substrate processing apparatus, includes: a substrate transfer mechanism configured to advance and retreat a holding body that holds a substrate by symmetrically arranging two link mechanisms each including a driving arm and a driven arm; a processing module; a rotation angle measuring part configured to measure a rotation angle the driving arms; a holding body detection part configured to detect that a specific portion of the holding body is located at a predetermined position; and a controller configured to execute a step of acquiring a measurement value of the rotation angle of the driving arm, a step of obtaining a moving average of the measurement value of the rotation angle, and a step of obtaining a correction amount of the rotation angle so that a substrate transfer position of the holding body of the substrate transfer mechanism for the processing module becomes a reference position.