Semiconductor Wafer Temperature Controller with Dynamic Master-Slave Switching
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Solution Overview
Problem
The master-slave control method for temperature control in semiconductor wafers faces issues with throughput due to temperature gradient inversions and inverse setpoint responses, leading to prolonged stabilization times and reduced efficiency.
Innovation Solution
A temperature control device with a master-slave switching unit that dynamically switches the master loop to the loop with the lowest temperature setpoint during heating and the highest during cooling, and a master-slave cancellation unit that cancels the master-slave relationship when a three-level temperature gradient is inverted, ensuring consistent and stable temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the master-slave control method is used with a fixed master loop having the highest temperature setpoint during heating, then the temperature uniformity can be maintained, but the throughput is reduced due to inverse responses and prolonged stabilization times
Solution Approach 1:
The patent applies dynamics by making the master loop selection dynamic rather than fixed. The controller dynamically determines which control loop should be the master loop based on the current heating or cooling state and temperature gradient direction. This allows the system to adapt its control strategy in real-time, preventing inverse responses and reducing stabilization time while maintaining temperature uniformity.
Solution Approach 2:
The patent changes the parameter of master loop temperature setpoint assignment based on the operational state. During heating, the loop with the highest temperature setpoint becomes the master, while during cooling, the loop with the lowest temperature setpoint becomes the master. This parameter change eliminates inverse responses and improves throughput without sacrificing temperature control stability.
2Adaptability or versatility
If the temperature setpoints are inverted to achieve different temperature gradients, then the temperature distribution can be adjusted, but the stabilization time increases due to errors from master-slave relationship
Solution Approach 1:
The patent makes the master-slave relationship dynamic by allowing the master loop to switch between different control loops depending on the desired temperature gradient direction. When the temperature gradient needs to be inverted, the system seamlessly transitions the master loop designation, avoiding the errors and prolonged stabilization times associated with fixed master-slave relationships.
3Stability of the object's composition
If the slave loop is set with an offset temperature against the master loop, then the temperature gradient can be maintained, but inverse responses occur during heating and cooling transitions
Solution Approach 1:
The patent eliminates the fixed offset temperature problem by dynamically selecting which loop serves as the master. Instead of having slave loops permanently offset from a fixed master, the system adapts the master loop selection based on whether the system is heating or cooling, ensuring all loops respond consistently in the same direction and eliminating inverse responses.
Data Source
AI summary
A temperature controller for a semiconductor wafer is configured to perform a temperature control on a plurality of temperature adjusters including a reference temperature adjuster to perform a temperature adjustment of the semiconductor wafer, in which a manipulated variable calculator to give a manipulated variable to a master loop and a slave loop includes a master-slave switching unit configured to switch between the master loop and the slave loop and a master-slave cancellation unit configured to cancel a setting of the master loop and the slave loop when a temperature setpoint of the slave loop is set to have a temperature gradient against a temperature setpoint of the master loop.