Liquid Metal Composition Control in PVD Evaporators
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Solution Overview
Problem
In high-speed physical vapor deposition (PVD) processes, the composition of liquid metal in an evaporator changes due to differing vapor pressures of metals, leading to enrichment with impurities and instability in the metal coating on substrates, which is costly to address with high-purity feeding materials and inefficient with existing external feeding methods.
Innovation Solution
An apparatus and method using two vessels to control the composition of liquid metal in an evaporator, employing magnetohydrodynamic (MHD) pumps and induction heating to circulate and mix liquid metal, with level and flow sensors, and valves to maintain a stable composition by compensating for evaporation rates through controlled feeding from a secondary vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high purity feeding material is used to address impurity enrichment, then coating quality is improved, but manufacturing cost increases considerably
Solution Approach 1:
The invention extracts and removes impurities from the liquid metal composition in the evaporator by utilizing the vapor pressure differences between metals. The system continuously monitors composition and adjusts feeding rates to compensate for preferential evaporation of high vapor pressure metals, thereby extracting impurities without requiring high purity feeding materials.
Solution Approach 2:
The invention implements a feedback control system that continuously monitors the liquid metal composition in the evaporator and adjusts the feeding rates from multiple vessels accordingly. This closed-loop control maintains stable coating composition by compensating for changes in real-time, eliminating the need for expensive high purity materials.
2Stability of the object's composition
If the evaporator size is increased to control liquid metal composition changes, then composition stability is improved, but space requirements in the vacuum chamber increase
Solution Approach 1:
The invention divides the liquid metal supply system into multiple separate vessels, each containing different metal compositions. This segmentation allows independent control of each metal's feeding rate to the evaporator, enabling precise composition management without requiring a larger evaporator volume.
Solution Approach 2:
The invention implements dynamic control of metal feeding rates based on real-time composition monitoring. The system continuously adjusts the feeding rates from multiple vessels to compensate for preferential evaporation, maintaining composition stability through active control rather than relying on large evaporator volume.
3Duration of action of moving object
If external liquid metal source is used to feed the evaporator, then composition control time is extended, but device complexity increases
Solution Approach 1:
The invention combines multiple liquid metal vessels with different metal compositions into a unified feeding system. By coordinating the feeding from multiple vessels simultaneously, the system achieves extended composition control duration while managing complexity through integrated control of multiple sources.
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 maintains a stable vapor composition and coating quality by continuously adjusting the liquid metal composition in the evaporator, reducing impurity enrichment and composition changes, while minimizing space requirements and operational costs.
Implementation Method 1
the means to feed the liquid metal from the first vessel to the evaporator comprises a supply line provided with a magnetohydrodynamic (MHD) pump
Implementation Method 2
Such an evaporator is for instance used in a physical vapour deposition (PVD) process wherein a metal vapour is deposited on a substrate
Data Source
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AI summary
The invention relates to an apparatus and method for controlling the composition of liquid metal fed to an evaporator in a vacuum chamber used in a physical vapour deposition process.