Case S14: Dual rotatory magnetron source for web coating
High material utilization and long target life make rotatory cylindrical sources ideal for coating of rolled substrates. Here we consider a process in which two rotatory cylindrical targets are employed to coat a web substrate conformed on a continuously rotating drum.
Two 120-cm-long cylindrical and rotatory targets, as in Case 13S, are employed here for coating of the 1-meter-wide web substrate. The magnets of the cathodes are rotated by a few degrees towards the drum axis to gain slightly in vapor collection and uniformity.
Similar to linear motions, the uncorrected thickness distribution across the substrate width exhibits a bow curve, as shown by the red points in the diagram below. The uncorrected distribution has a non-uniformity of +/-3.5%.
To improve the thickness uniformity, a correction mask pair can be installed. V-Grade 5S allows you to create a mask shape, free hand, in a trial-and-error process to obtain one that suppresses the non-uniformity; for further optimization you can engage the automated mask optimizer (a standard feature of V-Grade 5S). With a mask optimized in V-Grade 5S, the thickness non-uniformity is reduced to +/-0.31%, shown by the blue points in the above diagram.
With numerical aid, such as V-Grade 5S, in mask design one can achieve excellent thickness uniformity while blocking the least amount of material vapor, which means the lowest material waste and highest deposition rate.
