Measurement of Absolute Argon Excited State Populations and Electron Energy Distribution Functions in an Ar-a-Si Plasma

Deposition systems utilizing plasma are used for a variety of tasks, including tool coatings and creating thin-film materials. In order to have repeatable results, the internal conditions of a plasma chamber need to be known. This project centered on the use of data from optical emissions and a Langmuir probe from an argon plasma amorphous silicon depositing system. An electron energy distribution function (EEDF) was obtained from manipulation of the Langmuir probe data. This EEDF was then input to an argon collisional-radiative model (CRM) to obtain the electron population of the 4p level of the argon plasma. Through an absolute calibration, the same 4p population will be studied by the optical emissions experiment. The result from the Langmuir study was that the 4p population was 5x1013 m-3, while the optical emissions result was 2x1013 m-3. These are reasonably close values, well within a range of verification, but further study needs to be done to confirm these results.