Deposition Source Rate Filtering for Stable Film Thickness Control
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Solution Overview
Problem
Existing deposition systems for thin films in display devices face challenges in maintaining a stable film thickness due to temperature fluctuations of the heater, leading to deviations from the reference thickness, which affects the quality and efficiency of the deposition process.
Innovation Solution
A control system for the deposition source that includes a sensor to detect the deposition material, a rate calculator to calculate the deposition rate, a filter to remove noise from the rate, and a PID controller to adjust the heater power based on the filtered rate, ensuring the deposition rate remains within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a sensor detects deposition material amount and calculates deposition rate, then film thickness control is improved, but noise in the deposition rate signal causes instability in the control signal
Solution Approach 1:
A filter is introduced as an intermediary component between the deposition rate calculator and the controller. The filter processes the noisy deposition rate signal to generate a filtered deposition rate, which serves as a stable input for the controller. This mediator resolves the contradiction by allowing precise film thickness control through real-time monitoring while eliminating signal noise that would otherwise cause control instability.
Solution Approach 2:
The harmful noise component is extracted and removed from the deposition rate signal through the filter. By separating the useful deposition rate information from the noisy signal, the system achieves both precise film thickness control and stable control signals. The filter extracts only the meaningful deposition rate data while discarding the noise that would cause control instability.
2Reliability
If noise removal filter is applied to deposition rate signal, then control signal stability is improved, but control delay may occur
Solution Approach 1:
The filter applies noise removal selectively rather than uniformly to all signal conditions. By processing only the necessary portions of the signal and using appropriate filtering intensity, the system achieves control signal stability while minimizing the introduction of control delays. This partial action approach balances noise removal effectiveness with real-time control requirements.
3Manufacturing precision
If heater temperature is maintained within predetermined range, then film thickness precision is improved, but energy consumption increases
Solution Approach 1:
The system implements a closed-loop feedback control mechanism where the controller continuously monitors the filtered deposition rate and adjusts the heater power accordingly. When the deposition rate deviates from the target, the controller modifies heater power to correct the deviation, maintaining film thickness precision while optimizing energy consumption by applying heater power only when necessary rather than maintaining constant high power.
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
The control system stabilizes the deposition process by maintaining the film thickness close to the reference value, reducing thickness distribution and improving the quality of the display device while preventing control delays from noise removal.
Implementation Method 1
A deposition apparatus for performing the vacuum deposition method may include a deposition source
Implementation Method 2
a heater that heats the crucible
Implementation Method 3
the sensor may be a quartz crystal microbalance (QCM)
Data Source
AI summary
A control system of a deposition source includes a deposition source that includes a heater and provides a deposition material on a substrate, a sensor that detects an amount of the deposition material provided to the substrate, a rate calculator that calculates a first deposition rate based on the amount of the deposition material provided to the substrate, and a filter that calculates a second deposition rate by removing a noise from the first deposition rate. The control system of the deposition source may improve deposition quality by a stabilized signal by removing noise.