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The diffusion of ion implanted F in Si has been studied by the use of secondary ion mass spectroscopy and thermal desorption spectroscopy. In the dose range studied (below amorphization threshold), F exhibits an anomalous out-diffusion behavior which is characterized by the depletion of F in Si substrate at temperatures ≥550 °C with complete suppression of diffusion deeper into the bulk of Si. F species which migrate to the surface react with native oxide and Si to form volatile Si oxyfluoride and Si fluoride, which then evaporate from the surface. There is clear evidence that the formation of Si oxyfluoride correlates strongly with the thermally activated anomalous migration of F. While the driving force for the anomalous F migration has not yet been identified, it appears that the electric field is not a dominant mechanism.

Interconnect delay is shown to be a performance-limiting factor for ULSI circuits when feature size is scaled into the deep submicron region, due to a rapid increase in interconnect resistivity and capacitance. Dielectric materials with lower values of permittivity are needed to reduce the line-to-line capacitance as metal spacing decreases. However, the challenge is to successfully integrate these materials into on-chip interconnects. A new multilevel interconnect scheme has been developed that gives improved performance through insertion of a low-dielectric-constant material between metal leads. A novel polymer/Si02 composite dielectric structure provides lower line-to-line capacitance while alleviating many of the integration and reliability problems associated with polymers in standard interconnect processing.

The satellite structure in both core-level and valence-band photoemission spectra from singlecrystal MnO{100) has been studied by using both x-ray photoemission spectra and resonant photoemission. Only very weak satellites are present in the Mn 2p core-level spectra, while no satellite structure is evident in the Mn 3p and 3s core-level spectra. The small intensity of the satellite peaks in MnO is consistent with the trend predicted by a recent ligand charge-transfer screening model; such screening is quite weak in MnO in comparison to the heavier transition-metal oxides. The valence-band spectrum, however, exhibits a stronger satellite peak than predicted by the model, and its origin has been uncertain. We have found that, while the satellite in the valence-band spectrum can be resonantly enhanced across the Mn 3p -+3d optical excitation threshold, its intensity depends strongly upon surface treatment. The satellite disappears with only 0.2 -1-langmuir exposure of oxygen at 340 C, confirming that it is essentially a surface-related feature. We suggest that it is associated with point defects on the surface, presumably surface Mn vacancies.

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