Thermal Evaporation Control via Reflected Radiation Feedback
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Solution Overview
Problem
The evaporation rate and flux distribution of source materials in thermal evaporation systems using electromagnetic radiation are inherently unstable due to changes in the source surface shape and orientation, making it difficult to achieve consistent coating of target materials.
Innovation Solution
A method and system that control the evaporation rate by measuring reflected electromagnetic radiation, adjusting the position and power of the electromagnetic radiation source, and modifying the beam cross-section to maintain a consistent energy deposit on the source surface, allowing for closed-loop control of the evaporation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electromagnetic radiation is used for thermal evaporation of source material, then deposition of thin films at low pressures is achieved, but the evaporation rate and flux distribution become inherently unstable due to source surface shape changes
Solution Approach 1:
A detector measures the intensity of reflected electromagnetic radiation from the source surface and feeds this information back to a control system. The control system adjusts the electromagnetic radiation power or source position to maintain constant evaporation rate despite surface shape changes, resolving the instability problem while preserving high deposition productivity
Solution Approach 2:
The patent replaces mechanical monitoring of source surface shape with optical measurement of reflected radiation intensity. This substitution provides a non-contact, real-time measurement method that enables dynamic control without mechanical interference, maintaining both productivity and reliability
2Quantity of substance
If the source surface shape changes during evaporation, then material depletion occurs, but the evaporation rate and flux distribution become unstable
Solution Approach 1:
The detector continuously monitors reflected radiation intensity as the source surface depletes and changes shape. The control system uses this feedback to adjust radiation power or source positioning in real-time, maintaining consistent flux distribution to the target despite ongoing material depletion and surface morphology changes
Solution Approach 2:
The system dynamically changes operating parameters (radiation power, source-to-target distance, or beam focus) in response to detected surface changes. This allows the evaporation process to adapt to material depletion, maintaining manufacturing precision throughout the source material consumption cycle
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 enables precise adjustment of the evaporation rate, ensuring a stable and consistent coating of target materials by actively monitoring and adapting to changes in the source surface conditions, thereby improving the coating process efficiency.
Implementation Method 1
electromagnetic radiation impinges at an angle, preferably at an angle of 45°, on a source surface of the source material for a thermal evaporation and/or sublimation of the source material below the plasma threshold
Implementation Method 2
electromagnetic radiation impinges at an angle, preferably at an angle of 45°, on a source surface of the source material for a thermal evaporation and/or sublimation of the source material below the plasma threshold
Implementation Method 3
main detector for measuring electromagnetic radiation is arranged such that electromagnetic radiation reflected on the source surface reaches the main detector
Implementation Method 4
absorption body comprising an absorption surface for at least partly absorbing the electromagnetic radiation
Implementation Method 5
heat sensing element for measuring a temperature of the absorption body for detecting an absolute temperature and/or a temperature change caused in the absorption body by the absorbed electromagnetic radiation
Data Source
AI summary
The present invention relates to a method for controlling an evaporation rate of source material (20) in a system (10) for thermal evaporation with electromagnetic radiation (120), wherein the system (10) comprises an electromagnetic radiation source (110) for providing an electromagnetic radiation (120), a vacuum chamber (12) containing a reaction atmosphere (16) and a main detector (40, 100) for measuring electromagnetic radiation (120), wherein a source material (20) and a target material (18) to be coated are arranged in the vacuum chamber (12) and the electromagnetic radiation source (110) is arranged such that its electromagnetic radiation (120) impinges at an angle, preferably at an angle of 45°, on a source surface (22) of the source material (20) for a thermal evaporation and/or sublimation of the source material (20) below the plasma threshold, and wherein the main detector (40, 100) for measuring electromagnetic radiation (120) is arranged such that electromagnetic radiation (120) reflected on the source surface (22) reaches the main detector (40, 100), further wherein the source material (20) is provided by a source element (24), wherein the source surface (22) is located accessible for the electromagnetic radiation (120) at the source element (24), whereby the source element (24) is arranged in a holding structure (28) and movable by the holding structure (28) perpendicular to the source surface (22). Further, the present invention relates to a detector (40) for measuring electromagnetic radiation (120), the detector (40) preferably suitable for a method according to the present invention, and additionally to a system (10) for thermal evaporation with electromagnetic radiation (120) suitable for the method according to the present invention.