Substrate Heating Control for Vapor Phase Growth
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Solution Overview
Problem
Accurate temperature control of a substrate during vapor phase growth is challenging when a thin film causes thin-film interference, affecting the emissivity measured by radiation thermometers, leading to inaccurate temperature detection and feedback control.
Innovation Solution
Implementing a vapor phase growth method and device with a control unit that switches between temperature feedback control and constant output control, maintaining a consistent heating unit output despite changes in emissivity due to thin-film interference, ensuring precise temperature maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature feedback control is used to maintain substrate temperature, then temperature control accuracy is improved, but measurement accuracy deteriorates when thin film causes interference
Solution Approach 1:
The control method dynamically switches between temperature feedback control and constant output control based on the growth stage of the thin film. When the film thickness reaches a range that causes interference, the system transitions from feedback control to constant output control, adapting the control strategy to the current state to maintain reliability while avoiding measurement errors.
Solution Approach 2:
The system预先 identifies the film thickness range that causes interference and switches to constant output control before the interference significantly affects measurement accuracy. This preliminary action prevents the degradation of measurement reliability by proactively changing the control mode when the film reaches a critical thickness.
2Ease of operation
If radiation thermometer is used to measure substrate temperature, then temperature detection is enabled, but measurement accuracy deteriorates due to emissivity changes from thin film interference
Solution Approach 1:
The invention extracts the problematic thin film interference effect from the measurement system by switching to constant output control when the film thickness enters the interference range. This removes the source of measurement error by eliminating the feedback control loop that relies on inaccurate temperature readings during the interference regime.
Solution Approach 2:
The control system introduces an intermediary control mode (constant output control) that mediates between the radiation thermometer measurements and the heating unit. This intermediary mode allows the system to maintain stable heating without relying on inaccurate temperature measurements during thin film interference.
3Stability of the object's composition
If heating unit output is controlled based on temperature feedback, then temperature uniformity is improved, but control stability deteriorates when thin film interference occurs
Solution Approach 1:
The control system dynamically adjusts the heating strategy based on film thickness. During the interference-prone stage, it switches to constant output control which provides inherent stability by eliminating the feedback loop that would otherwise amplify measurement errors. This dynamic adaptation maintains temperature stability while accounting for the changing optical properties of the growing film.
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 allows for high-accuracy temperature control of the substrate even when thin-film interference occurs, maintaining uniform film thickness and quality by stabilizing the heating unit output, thereby overcoming the limitations of inaccurate temperature detection.
Implementation Method 1
measuring a temperature of the substrate with a radiation thermometer
Implementation Method 2
heating the substrate with a heating unit
Implementation Method 3
a first film causing thin-film interference at a measuring wavelength of the radiation thermometer
Data Source
AI summary
A vapor phase growth method of growing a film on a substrate by supplying material gases to the substrate while heating the substrate with a heating unit according to an embodiment, the method includes: measuring a temperature of the substrate with a radiation thermometer; executing a temperature feedback control to control an output of the heating unit to cause a measurement value of the radiation thermometer to have a set value when a film is not grown on the substrate; and executing a constant output control to maintain an output of the heating unit constant when a film causing thin-film interference in a wavelength measured by the radiation thermometer is grown on the substrate.