SiC Substrate Temperature Control via Stepwise Emission Current
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Solution Overview
Problem
Large-diameter silicon carbide (SiC) substrates require stable and rapid heating for activation annealing, but existing PID control methods lead to temperature instability and lower throughput due to increased heat capacity and responsiveness issues in substrate heat treatment apparatuses.
Innovation Solution
A temperature control method that reduces the emission current value in a stepwise manner after reaching a preset temperature, maintaining the treatment temperature at a fixed value until the annealing process is complete, enhancing temperature responsiveness and stability during rapid heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the heat capacity of the heater is increased to handle large-diameter SiC substrates, then the substrate treatment capability is improved, but the temperature responsiveness deteriorates
Solution Approach 1:
The patent applies dynamic control by switching between constant emission current control and PID control based on temperature stages. During rapid heating phase, constant emission current provides aggressive heating power; during stabilization phase, PID control provides precise temperature maintenance, optimizing both heating speed and temperature stability for large-diameter substrates
Solution Approach 2:
The patent changes the control parameter from emission current to PID control parameters at a specific temperature threshold. This parameter transition allows the system to exploit the advantages of both control methods: high-power rapid heating followed by precise temperature stabilization, effectively resolving the responsiveness-stability tradeoff
2Stability of the object's composition
If PID control is used for temperature stabilization, then temperature stability is improved, but the heating speed deteriorates due to hunting occurrence
Solution Approach 1:
The patent segments the heating process into two distinct stages: rapid heating stage using constant emission current control, and stabilization stage using PID control. This temporal segmentation allows each control mode to operate in its optimal performance range, achieving both high heating speed and stable temperature control without the hunting phenomenon that plagues continuous PID control during rapid heating
3Stability of the object's composition
If the temperature is increased slowly to avoid hunting, then temperature stability is improved, but the throughput deteriorates
Solution Approach 1:
The patent implements periodic control action by switching between two control modes at a defined temperature threshold. The system periodically transitions from aggressive constant current control to gentle PID control, achieving rapid heating followed by stable maintenance, thereby maximizing throughput while ensuring temperature stability throughout the annealing process
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 ensures high throughput and stability in the activation annealing treatment of large-diameter SiC substrates by improving temperature control responsiveness, allowing for efficient semiconductor device manufacturing.
Implementation Method 1
thermal electrons generated from the filament being accelerated by an accelerating voltage applied between the filament and the heating container from an accelerating power source
Implementation Method 2
the heating container being heated by causing the accelerated thermal electrons to collide with the heating container
Data Source
AI summary
The present invention provides a temperature control method for a substrate heat treatment apparatus that achieves high throughput while securing stability in rapid heating where a large-diameter silicon carbide (SiC) substrate having impurity ions implanted thereinto is subjected to an activation annealing treatment.A temperature control method for a substrate heat treatment apparatus (1) that includes a heating element includes: increasing the treatment temperature; continuing the temperature increase by reducing the value of power in a stepwise manner after the treatment temperature reaches a preset temperature (T1) before reaching the annealing temperature, the power being applied to heat the heating element; and maintaining the treatment temperature at a fixed value until an annealing treatment is completed after the treatment temperature reaches the annealing temperature (TA).