Electric Heater Ramp-Down Control for Runaway Zone Deviations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing thermal systems with resistive heating elements in semiconductor processes experience inefficiencies in temperature adjustment, leading to non-productive manufacturing time due to standard ramp rates and issues like zone-to-zone deviations and runaway conditions during temperature changes.
Innovation Solution
Implementing a variable ramp rate control system that adjusts power to resistive heating elements based on real-time monitoring, using weighted values to correct for runaway conditions such as zone-to-zone deviations and ramp setpoint deviations, ensuring coherent temperature profiles during both ramp-up and ramp-down processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a standard ramp rate is used to adjust temperature, then the heater reaches the temperature setpoint, but non-productive manufacturing time increases
Solution Approach 1:
The patent implements a variable ramp rate control system that dynamically adjusts the temperature change rate based on real-time monitoring of zone temperatures. Instead of using a fixed standard ramp rate, the system modifies the ramp rate adaptively to optimize heating efficiency while preventing runaway conditions, thereby reducing non-productive time without compromising safety.
Solution Approach 2:
The system continuously monitors zone temperatures and uses this feedback to adjust the ramp rate. When zone-to-zone deviations are detected, the control system modifies the ramp rate to correct the deviation, creating a closed-loop control mechanism that optimizes temperature adjustment speed while preventing thermal runaway.
2Loss of time
If a higher ramp rate is used to reduce non-productive time, then temperature adjustment speed increases, but runaway conditions occur
Solution Approach 1:
The system dynamically adjusts the ramp rate based on real-time thermal conditions. When the system operates normally, a higher ramp rate can be used to reduce non-productive time. When zone-to-zone deviations indicate approaching runaway conditions, the ramp rate is automatically reduced to maintain thermal stability, thus resolving the contradiction between speed and safety.
Solution Approach 2:
The control system detects early signs of runaway conditions through zone temperature monitoring and takes preliminary corrective action by adjusting the ramp rate before thermal runaway occurs. This preventive approach allows the system to maintain higher ramp rates during normal operation while preventing instability issues.
3Productivity
If variable ramp rate control is implemented to optimize temperature adjustment, then manufacturing efficiency improves, but system complexity increases
Solution Approach 1:
The variable ramp rate control system uses feedback from zone temperature sensors to automatically adjust the ramp rate. This feedback mechanism enables optimized temperature control without requiring complex manual intervention, as the system self-regulates based on real-time conditions, thereby improving efficiency while keeping the control architecture manageable.
Solution Approach 2:
The control system performs self-adjustment of the ramp rate based on zone temperature deviations. The system monitors its own thermal state and automatically modifies operating parameters to maintain optimal performance, reducing the need for external control complexity while improving manufacturing efficiency.
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 reduces non-productive time by optimizing temperature adjustments, maintaining consistent zone temperatures, and preventing thermal stress, thereby enhancing manufacturing efficiency.
Implementation Method 1
a heater having resistive heating elements
Data Source
AI summary
A method of controlling a temperature of a heater including a plurality of resistive heating elements that define a plurality of zones includes applying power to at least one resistive heating element of the plurality of resistive heating elements at a variable ramp rate to decrease the temperature of the heater to a temperature setpoint where the variable ramp rate is set to a desired ramp rate. The method further includes monitoring the temperature of the heater to detect at least one runaway condition and based on the detection of more than one of the at least one runaway condition, assigning a weighted value to a reduction amount associated with each of the at least one runaway condition. The method further includes adjusting the variable ramp rate from the desired ramp rate to a permitted ramp rate by the reduction amount.