Method for manufacturing a compound film

A method of manufacturing a compound film layer, comprising:

• forming the compound film layer composed of at least a first material and a second material on a first surface of a flexible substrate as the flexible substrate is transferred in a first direction relative to a first deposition source, a second deposition source and a third deposition source, wherein forming the compound film layer on first surface of the flexible substrate further comprises:
• heating an amount of the first material disposed in the first deposition source to form a first flux that is received by the first surface;
• heating an amount of the second material disposed in the second deposition source to form a second flux that is received by the first surface;
• and
• heating an amount of the first material disposed in the third deposition source to form a third flux that is received by the first surface, wherein the first material and the second material have a different composition, and the first, second and third deposition sources are disposed a distance apart along the first direction;
• measuring a property of the compound film layer using a fluorescence spectrometer that is positioned over a second surface of the flexible substrate, wherein the second surface is opposed to the first surface of the substrate, the substrate is disposed between the measurement device and the first, second and third deposition sources, and the property of the compound film layer is selected from a group of properties consisting of thickness and composition;
• and
• adjusting the first flux, the second flux or the third flux based on a comparison of the measured property and a predefined value.