RECONSTRUCTED 2-DIMENSIONAL DOPING PROFILES FROM MULTIPLE ONE-DIMENSIONAL SECONDARY ION MASS-SPECTROMETRY MEASUREMENTS

Two-dimensional doping profiles can be determined from multiple one-dimensional secondary ion mass spectrometry (SIMS) profiles using computed tomography techniques. The chemical nature of SIMS enables the measurement of both as-implanted and annealed profiles with this technique. Mechanical lapping was done of multiple samples to expose different faces of the substrates followed by one-dimensional SIMS measurements. Doping profiles of 0.4-mu-m boron junctions have been measured and reconstructed using the maximum likelihood estimation algorithm. Issues of sample alignment, SIMS depth resolution and SIMS sensitivity are discussed with respect to the application of this technique to sub 100 nm junctions.