YELLOW EMISSION BANDS PRODUCED DURING GOLD ETCHING IN O2-CF4 RF GLOW-DISCHARGE PLASMAS - EVIDENCE FOR GAS-PHASE AUF

Distinctive optical emission bands have been observed during the etching of gold films in O2-CF4 and O2-SF6 rf glow-discharge plasmas. We suggest that the emission originates from gas-phase AuF, although AuO and the molecular ions AuF+ and AuO+ cannot be definitively ruled out as the emitting species. No optical spectra have previously been reported for any of these species in the gas phase. Conditions for producing the emission bands are outlined, and a representative spectrum is provided. Band positions for the tentatively identified (upsilon' = upsilon", upsilon") and (upsilon' = upsilon" -1, upsilon") progressions could be reproduced with a (0,0) band origin nu(00) = 17 757 cm-1, vibration frequencies omega(e)' = 529.5 cm-1 and omega(e)" = 560 cm-1, and vibrational anharmonicities omega(e)'x(e)' = 2.5 cm-1 and omega(e)"x(e)" = 1.0 cm-1, where the vibrational energies relative to the upsilon = 0 levels are given by G0(upsilon) = (omega(e) - omega(e)x(e))upsilon - (omega(e)x(e))upsilon(2). The band structure could be qualitatively accounted for by a (1)PI - (1)SIGMA band system with an assumed B(e)" of 0.24 cm-1, B(e)' = B(e)" + 2.75 x 10(-3) cm-1, alpha(e)' = 4.5 x 10(-3) cm-1, and alpha(e)" = 1.0 x 10(-3) cm-1, where the rotation constants are given by B(upsilon) = B(e) - alpha(e) (upsilon + 1/2).