Abstract

The depth profiling of dopant concentrations across ultrathin device structures is critical to microelectronic device design and fabrication. Secondary Ion Mass Spectrometry (SIMS) remains an extremely important technique for semiconductor characterization. However, secondary ion production during sputtering is extremely dependent on matrix composition, complicating the characterization of elemental concentrations at or near the interfaces of two materials. For this reason, complementary analytical techniques referred to as Sputtered Neutrals Mass Spectrometry (SNMS) have been developed. In SNMS, a laser beam is used to ionize the neutral species in the gas phase above the sample after ion beam sputtering. These "post-ionization" techniques can accomplish surface analysis and depth profiling with high sensitivity and relative freedom from matrix effects. The application of ultra-high intensity lasers (>10¹⁴ W / cm²) to the post-ionization technique creates the possibility that all the sputtered species, regardless of electronic structure, will be non-resonantly ionized with high efficiency¹. Uniform ionization of all the sputtered species within the laser volume will greatly simplify the quantification of unknown materials.

© 1996 Optical Society of America