Thin Film Thickness Calculator

This calculator turns a deposition rate and time into a film thickness (thickness = rate × time) and then derives several properties useful for thin-film process control and optics. It also inverts the calculation to solve for the deposition time needed to hit a target thickness, which is handy for planning a run before you start the tool. Optical path length (n × thickness) and the first-order interference wavelength (2 × n × thickness) are computed from the film's refractive index — this is the simplified thin-film interference relationship for constructive reflection at normal incidence, useful for predicting the visible interference color of the film (the same physics behind oxide-color charts used to gauge silicon dioxide thickness by eye).

Note that this uses the basic 2nt relationship without accounting for any phase shift from the underlying substrate's refractive index, so treat the predicted color as an approximation. The atomic-layer count assumes a generic ~0.3 nm per monolayer, and the areal mass density calculation is hard-coded to silicon dioxide's density (2.2 g/cm³) regardless of what refractive index you enter — so if you're modeling a higher-index material like TiO2 or Si3N4, the mass-per-area figure will not match your actual film and should be ignored or recalculated separately. As always, calibrate your deposition rate against an actual ellipsometry or profilometry measurement rather than trusting rate specs alone, since real deposition rates drift with tool conditioning and target age.