Optical Emission Spectroscopy of Hydrogen Plasma Inside Microwave Plasma CVD Reactor

Last few decades, with the increase of modern technology, hydrogen plasma has been extensively consumed in the semiconductor industries, thin film and coating industries for silicon and diamond deposition. In the current paper, hydrogen plasma characteristics were studied using optical emission spectroscopy (OES) by varying microwave power and pressure separately and simultaneously inside a quartz bell jar in a 915 MHz microwave plasma enhanced chemical vapor deposition (MPCVD) system for diamond deposition. Hα, Hβ lines and Fulcher α H2 band were detected at the wavelengths of 655.95 nm, 485.7 nm and 560 nm to 640 nm, respectively. The line intensities of Hα
and Hβ were decreased with increasing pressure at constant microwave (MW) power and these line intensities were increased with increasing MW power at a fixed pressure. The ion density initially increased and then decreased with increasing pressure further. When MW power and pressure were increased simultaneously, the intensities of Hα and Hβ lines were initially decreased and after a critical value of MW power and pressure Hα and Hβ intensities were increased. Atomic silicon emission lines were detected by using at 70 Torr pressure and 5000 W microwave power indicating that CH4 needed to be added before the silicon etching for the diamond deposition recipe.