The National Technology Roadmap of Semiconductors (NTRS) shows that future semiconductor processing will require the formation of junctions less than 30nm deep with gate lengths approaching, and becoming less than, 0.lum. Techniques must be available to measure these in-depth, as well as spatial, distributions.
Secondary ion mass spectrometry (SIMS) has long been the technique of choice for measuring dopant profiles in semiconductors. The depth of the junctions formed has, up top now, always been sufficiently deep into the semiconductor that the effects of the analysis on the measured profile (i.e. atomic mixing) could be ignored for the most part. In addition, gate lengths have been sufficiently large that diffusion of LDD implants under the gate have not contributed significantly to short-channel effects. However, the relentless decrease in the required junction depths and gate lengths may mean that the situation may change in the near future.