Modeling of Complex Deposition Processes
Some physical vapor deposition (PVD) processes are more complex than others. Examples of complex processes may be found in manufacturing of OLED panels and the emerging thin-film anode batteries. 

To achieve high realism, a numerical model must include all the relevant elements of the process. The diagram below illustrates what a “real-world” process may entail. 

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Here, we call to attention the difference between cold and hot partition walls, either kind may be employed to confine the material vapor. While a cold wall simply condenses vapor particles, a hot wall reemits particles that it intercepts. 

Hot walls must be treated as secondary vapor sources in order for a numerical model to yield realistic thickness distributions and deposition rates. With suitable tools, such a model can be constructed in a straightforward fashion by noticing: 
The diagrams below show the differences between hot walls and cold walls in a deposition of metal indium, modeled with V-Grade 5S Pro tool set (Tin Model LLC). The metal is evaporated from a pan crucible to coat a substrate that transits through the deposition zone (50 cm wide) defined by four walls – they are either heated to prevent condensation or unheated to allow films to build up. In modeling, the heated walls are treated as secondary sources according to the equality shown above. 
Heated walls afford an advantage in deposition rate: the layers are 35% thicker than what result from cold walls, after the same transit. There is also a significant difference in the thickness distribution. One can employ a pair of correction masks to obtain thickness uniformity, with result shown in (b) of above diagrams. 

Sometimes the distinction between hot and cold walls may be unclear. This and other nuances should be properly handled in order for a numerical model to yield results with high accuracy and predictive value. Please visit a Tin Model webpage where some of these details are explained. 

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