New Devices for the Production of Intense Pulsed Jets of CF2: Laser Spectroscopic Characterization

Abstract

AbstractWe report the development of two new sources for the production of intense pulsed jets of atomic and molecular free radicals. The present work applies these sources to the generation of the widely used semiconductor etchant, CF2, in each case characterizing the yield and internal energy distribution of this diradical by laser induced fluorescence. The methods employed modify a commercial high-vacuum compatible pulsed molecular beam valve to accept either a glow discharge or pyrolysis nozzle. The source compound for both systems is hexafluoropropylene oxide (HFPO). In each case measured yields of CF2 are high: For pyrolysis we find intensities as great as 5×1017 sr−1sec−1 representing nearly complete conversion of HFPO to CF2 + CF3CFO. The discharge source yields about an order of magnitude less CF2 intensity in a shorter beam-pulse which also contains ions and other atomic and molecular radicals. The vibrational energy distribution of the CF2 varies with source conditions, with the hottest CF2 produced by the pyrolysis source at high temperature.