Vacuum Coating Feedback Control for Uniform Layer Properties
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Solution Overview
Problem
Vacuum coating processes face challenges in controlling the properties of single or multilayer coatings on substrates, particularly in achieving uniformity over large areas and real-time monitoring and correction of manufacturing variances, leading to yield loss and sub-optimal product quality.
Innovation Solution
A feedback system that employs multiple measurement techniques, including spectral transmission and other non-contact methods, to monitor layer properties in real-time, using a processing unit to determine actual values and deviations from desired values, and a controller to adjust process parameters based on a layer model, ensuring properties lie within predetermined tolerance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurement techniques are used to monitor layer properties, then measurement precision and control capability are improved, but device complexity increases
Solution Approach 1:
The measurement system is segmented into multiple independent measurement techniques, each targeting specific layer properties. Different measurement techniques are applied to different locations on the substrate, allowing specialized measurement of thickness, optical constants, and other properties without requiring a single complex universal measurement device.
Solution Approach 2:
The feedback control system is designed to be universal by integrating multiple measurement techniques and a layer model that can handle various layer properties. The system can monitor and control different properties (thickness, optical constants, composition) using a unified control architecture that processes data from diverse measurement sources.
2Manufacturing precision
If real-time monitoring and control is implemented, then manufacturing precision and product quality are improved, but device complexity and measurement requirements increase
Solution Approach 1:
A feedback control system is implemented where measurement data from multiple techniques is continuously monitored and fed back to adjust deposition parameters in real-time. The system compares measured layer properties with target values and automatically adjusts process parameters to maintain manufacturing precision within specified tolerances.
Solution Approach 2:
A layer model is developed beforehand that expresses layer properties as a function of deposition parameters. This model is used in advance to predict the relationship between process settings and layer outcomes, enabling the feedback system to make informed adjustments and anticipate required parameter changes before deviations occur.
3Productivity
If in-line measurements are performed during the coating process, then productivity and yield are improved, but measurement system complexity and process control difficulty increase
Solution Approach 1:
Measurement techniques are selected and configured before the coating process begins, with measurement locations and parameters predetermined based on the layer stack design. This preliminary setup enables seamless in-line measurements during production without requiring complex real-time decision-making about what to measure and where.
Solution Approach 2:
Traditional mechanical contact measurement methods are replaced with non-contact optical and electromagnetic measurement techniques that can operate in-line during the vacuum coating process. These substitution methods enable measurement without breaking vacuum or physically contacting the substrate, maintaining productivity while reducing measurement complexity.
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 solution enables real-time control and uniformity of layer properties, reducing yield loss and improving product quality by allowing immediate correction of deviations during the vacuum coating process.
Implementation Method 1
at least two distinct measurement techniques for determining measurement signals at each of a plurality of locations spatially distributed over the coated substrate, whereby a first measurement technique is adapted for being applied simultaneously to a plurality of locations, and a second measurement technique is adapted for being applied to at least one location, one of the first and second measurement techniques being a spectral transmission measurement
Implementation Method 2
Some gas atoms are ionised and the sputtering target is bombarded with these ions, causing atoms to be detached from the sputtering target, and deposited on the substrate
Data Source
AI summary
A feedback system for controlling properties of a single layer or multiple layer stack is applied on a substrate by means of a vacuum coating process controlled by a plurality of process controlling means. The system includes at least one monitoring device for at least implementing at least two distinct measurement techniques for determining measurement signals at each of a plurality of locations spatially distributed over the coated substrate; at least one processing unit adapted for at least receiving the measurement signals; and a controller for at least providing actuation signals for actuating the plurality of process controlling means.