Ion and substrate effects on surface reactions of CF2 using C2F6, C2F6/H-2, and hexafluoropropylene oxide plasmas

The surface reactivity of CF2 radicals has been characterized during plasma processing of a variety of substrates using the imaging of radicals intera cting with surfaces technique. The plasma molecular beam sources are 100% C 2F6, 50/50 C2F6/H-2 and 100% hexafluoropropylene oxide (HFPO) gas mixtures. Simulation of spatially resolved laser-induced fluorescence images in the 100% C2F6, system shows that CF2 has a scatter value, S, >1.0 with SiO2, po lyimide and photoresist substrates. A scatter of >1.0 indicates that CF2 mo lecules are generated at the surface during plasma processing. With the 50/ 50 C2F6/H-2 plasma, CF2 exhibits a lower scatter value (similar to0.85) on Si, SiO2, and polyimide substrates. With the HFPO plasma source, S greater than or equal to1 for all continuous wave powers and substrates processed. Values of S similar to0.8 are obtained for ion-free and pulsed plasmas, how ever, revealing ion collisions with the substrate play an important role in the surface generation of CF2. The radical-surface interaction data are co rrelated with data from surface characterization by x-ray photoelectron spe ctroscopy and Fourier transform infrared spectroscopy of the substrates. Th e key finding is that our results suggest the surface reactivity behavior o f CF2 radicals correlates well to the overall plasma process (etching or de position). (C) 2000 American Vacuum Society. [S0734-2101(00)02406-4].