Optical Coating Parameter Correction for Thickness Accuracy

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Solution Overview

Problem

Coating systems face challenges in maintaining stable coating rates over the life of a target due to environmental changes and target geometry, leading to inaccurate layer deposition and reduced throughput, as existing methods like reverse engineering and leapfrogging are time-consuming and prone to errors.

Innovation Solution

Implementing forward parameter correction and enhanced reverse engineering based on expected deterministic process parameter drifts, using historic relationships between coating rate and target life to adjust run parameters dynamically, allowing for more accurate and consistent coating thickness control across multiple runs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If coating systems operate over the life of a target without parameter correction, then productivity is maintained through continuous operation, but manufacturing precision deteriorates due to coating rate drift and target geometry changes

Engineering Contradiction:

Improvecontinuous operationVSAvoidcoating thickness accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary characterization of target geometry changes and coating rate drift before actual coating runs. By pre-determining correction factors based on target life stage and geometric changes, the system can apply forward parameter corrections proactively, preventing thickness deviations before they occur during production runs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback loops where actual coating results and target geometry measurements are continuously fed back to adjust run parameters. This closed-loop control allows the system to compensate for drift in coating rates by dynamically modifying deposition parameters based on real-time and historical data, maintaining precision throughout target life.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If calibration runs are performed frequently to maintain accuracy, then manufacturing precision is improved, but productivity decreases due to reduced throughput

Engineering Contradiction:

Improvelayer thickness accuracyVSAvoidthroughput

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

Instead of performing calibration runs periodically during production, the system performs preliminary characterization and establishes correction models before production begins. This upfront preparation eliminates the need for frequent interruptive calibration runs, maintaining both accuracy and continuous throughput.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses its own operational data and target geometry information to self-correct parameters without requiring external calibration standards or interruptive calibration procedures. By leveraging process data and predictive models, the system maintains accuracy autonomously during continuous operation.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If run parameters are adjusted dynamically based on target life, then manufacturing precision is improved through consistent coating thickness, but device complexity increases

Engineering Contradiction:

Improvecoating thickness consistencyVSAvoidparameter correction system

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system systematically varies run parameters based on target life stage and characterized geometry changes. By establishing predetermined parameter adjustment schedules based on target age and measured geometric drift, the system maintains coating precision through controlled parameter evolution rather than complex real-time adjustments.

Inventive Principle:

Principle #35Parameter changes

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 improves the accuracy and consistency of coating rates, enabling more frequent and reliable leapfrogging, reducing the need for calibration runs, and maintaining desired values, thus enhancing the overall efficiency and quality of the coating process.

Implementation Method 1

A coating system may be used to coat a substrate with a particular material. For example, a sputtering system may be used for deposition of thin film layers, thick film layers

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

a sputtering system may be used for deposition of thin film layers, thick film layers

Methodology Applied

Scientific EffectSputtering: Sputtering

Data Source

PatentUS20210332474A1Coating control using forward parameter correction and adapted reverse engineering

Publication Date: 2021.10.28 VIAVI SOLUTIONS INC(US)

AI summary

A device may include one or more memories and one or more processors, communicatively coupled to the one or more memories, to receive design information, wherein the design information identifies desired values for a set of layers of an optical element to be generated during one or more runs; receive or obtain historic information identifying a relationship between a parameter for the one or more runs and an observed value relating to the one or more runs or the optical element; determine layer information for the one or more runs based on the historic information, wherein the layer information identifies run parameters, for the set of layers, to achieve the desired values; and cause the one or more runs to be performed based on the layer information.