Case 18: Tilt Dome Planets
In this example we examine a more rare kind of planetary-rotation coater: spherical and tilt domes as the planetary fixtures.
We copy the geometry of Case 17 except that the substrates are carried by spherical dome surfaces, as shown in the chamber diagram below. The radius of curvature of the dome is 50 cm; the rim-to-rim distance is also 50 cm. No masks are present.
After some optimization of the source location we obtain the outcome shown in the result panel below: the thickness nonuniformity across the entire surface is 0.09%; the material-collection efficiency is 50.8%.
The extraordinary thickness uniformity and material collection is obtained without the aid of any correction mask.
Like other types of tooling and fixturing that we analyzed previously, this coater has its own characteristic vapor-incident-angle histograms, which are displayed in the result panel shown above. These histograms hold clues to some of the important properties of the deposited layers, such as thickness distribution, step coverage and, in some case, physical properties of the deposited materials. Sometimes, the difference in the histograms may explain why certain physical properties of the deposited materials are different for substrates mounted at different locations of a fixture.
