Perpendicular-flow, single-wafer atomic layer deposition reactor chamber design for use with in situ diagnostics

A description is given of the design and performance of a diagnostic-accessible, perpendicular-flow, single-wafer deposition reactor for use with 50 mm wafers. The reactor chamber design is based on a simple flow tube, with diagnostic access achieved by replacing sections of the reactor chamber wall with recessed diagnostic ports. Reactor chamber performance is evaluated for the purpose of performing optical measurements during atomic layer deposition (ALD). Computational fluid dynamics simulations predict that the when used with windows the diagnostic port design produces minimal perturbations to the gas flow under typical deposition conditions, as compared to a design without diagnostic ports. Temperature measurements of the inside surface of a window installed in a diagnostic port suggest that for reactor chamber operation at 110 °C, under typical deposition conditions, the inside surface window temperature is approximately equal to or greater than the surrounding reactor chamber temperature, thereby minimizing possible species condensation on the window surface. As a consequence of using recessed diagnostic ports, an increase in the amplitude of optical intensity fluctuations was generally observed when performing measurements at elevated chamber temperatures. These intensity fluctuations could be readily reduced by enclosing the optical path to the exterior side of the windows. The performance of two straight-forward methods to reduce these intensity fluctuations is presented. The results outlined above demonstrate that this reactor design can be operated with short gas residence times and with all reactor surfaces at elevated temperatures, making it useful for simulating a wide range of gas flow conditions with relevance to microelectronics-related ALD processes.