Method for monitoring process endpoints in a plasma chamber and a

Abstract

Thin film deposition process endpoints and in situ-clean process endpoints are monitored using a single light filter and photodetector arrangement. The light filter has a peak transmission proximate a characteristic wavelength of the deposition plasma, such as Si, and one of the plurality of reaction products, such as NO, in the plasma chamber during in-situ cleaning. Emissions passing through the filter are converted to voltage measurements by a photodetector. In deposition endpoint monitoring, emission intensity of the Si emissions reflected off the surface of the substrate oscillate as deposition thickness increases, with each oscillation corresponding to a definite increase in thickness of the film. The endpoint of the deposition is reached when the number of oscillations in signal intensity versus time corresponds to a desired film thickness. Alternatively, a deposition rate for the film is calculated from the oscillation frequency of emissions reflected off the substrate. Endpoint occurs when the integrated deposition rate corresponds to the desired film thickness. In in-situ clean endpoint monitoring, the endpoint of the process is reached when emission intensity of the particular reaction product decreases to a substantially steady state value, meaning that the reaction is complete.