Atomic layer deposition in traveling-wave reactor: In situ diagnostics by optical reflection

The traveling-wave reactor is an effective instrument for performing atomic layer deposition (ALD). In this paper, the use of a Brewster-angle interferometric reflectance technique for in situ real-time monitoring of ALD growth of transparent thin films on transparent and non-transparent substrates in suited traveling-wave reactors is proposed and analyzed on the basis of a classical four-phase approximation. An appropriate experimental reactor system is described. The technique is applied to the diagnostics of TiO2 growth from TiCl4 and H2O. Features of the reflectance signal in the conditions of time-homogeneous ALD growth are discussed.