Semiconductor profiling with sub-nm resolution: Challenges and solutions

The application of secondary ion mass spectrometry in recent semiconductor applications has highlighted the need for extremely high depth resolution. The depth resolution limitations arise from the high dose, energetic interactions of the primary ion with the sample, leading to profile distortions due to the primary incorporation process and the collision cascades. Evolutionary and revolutionary approaches are presently proposed as potential solutions to achieve the ultimate in depth resolution. Evolutionary concepts are based on using extremely low bombardment energies (∼100 eV) and/or cluster beams whereas revolutionary concepts such as zero-energy SIMS and the tomographic atomprobe remove the primary ion beam completely.