Paper PS1-ThA4
Investigation of Fluorocarbon PECVD During Processing of Si and ZrO₂ Surfaces

Thursday, November 12, 2009, 3:00 pm, Room A1

Films deposited from fluorocarbon (FC) plasmas exhibit low dielectric constants desirable for interlayers in ultra-large scale integrated circuits (ULSIs). The processing of ULSIs has involved the use of small monomer (CF₄, C₂F₆) FC precursors as an avenue for plasma-enhanced chemical vapor deposition (PECVD). To gain a broader understanding of both the FC plasma system and plasma-surface interactions, we have explored gas phase diagnostics and species-surface reactivity under varying plasma parameters. This presentation will reflect upon data obtained from optical emission spectroscopy (OES) concerning the role of excited state species present in FC plasmas. OES data show that during FC plasma treatment of Si and ZrO₂ wafers, CF₂* concentrations increase independent of feed gas and substrate type. The films deposited from such treatments do, indeed, consist of FC moieties and thus plasma-surface interactions are clearly influential in the overall process. We have studied the interaction of FC plasma species at the interface of depositing films using the imaging of radicals interacting with surfaces (IRIS) technique. IRIS data show that scatter probabilities for the CF₂ radical are greater than unity, indicating that CF₂ is produced from films at the surface during FC plasma processing of silicon. Furthermore, we have used quadrupole mass spectrometry to investigate mean ion energies of CF₂⁺ in FC plasmas and have discovered that ion energies increase with increasing applied rf power. We have previously demonstrated that IRIS scatter coefficients for CF₂ produced from larger precursors (C₃F₈ and C₄F₈) correlate directly with ion energy. Thus, we will explore the role of this radical during processing of Si and ZrO₂ with small FC precursors as monitored by IRIS studies and compare these results with the respective ion energies for CF₂⁺ in these systems.