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SIMS: Secondary Ion Mass Spectrometry   Principle of measurement When ion beams (primary ions) of O2+ and Cs+ having energy of several tens of keV are emitted to a sample surface, the atoms on the sample surface are discharged in vacuum by sputtering. Although most of the sputtered area is electrically neutral, part of the area (normally 1% or less) is ionized positively or negatively (secondary ions). SIMS extracts the secondary ions by the electric field and analyzes the ions by mass spectrometry using the magnetic field and radiofrequency field to qualitatively and quantitatively determine the composition on the sample surface.

Major analytical applications for semiconductor materials  1.Dopant profile evaluation The in-depth distribution of density of N- and P-type dopants can be measured. The major evaluation items are shown below. Evaluation of dose, Rp and Xj Measurement of p/n junction depth Evaluation of profile changes after thermal processing Evaluation of channeling Evaluation of cross contamination Evaluation of energy contamination Comparison with SRP (spreading resistance profile) Comparison with results obtained by simulation, such as SUPREM Evaluation of ultra-low energy ion implantation   2. Evaluation of impurities and analysis of thin films The in-depth concentration distribution of impurities existing near the wafer surface, in the film and on the interface can be measured in various processes. The major evaluation items are shown below. Evaluation of metallic contamination during ion implantation Evaluation of impurities after dopant diffusion Evaluation of impurities in film deposited by sputtering and CVD Evaluation of impurities in CZ-Si and Epi-Si substrates Evaluation of changes in in-depth concentration of B and P in BPSG films Evaluation of segregation of C and O in various metallic interfaces Evaluation of diffusion on various metallic films Evaluation of nitrogen concentration in ultra-thin oxide film   3. Failure analysis and analysis of micro areas For failure analysis of actual devices, impurities in specific areas can be evaluated. For analysis of micro areas, image processing is used. The major evaluation items are shown below. Evaluation of impurities in transistor In-depth analysis of Al pad Evaluation of impurities in buried area Evaluation of B concentration in micro area   4. Other applications When the shape of the surface of a material is significantly deformed by sputtering or migration is caused during measurement by SIMS, the material is subjected to special analysis. The major evaluation items are shown below. Evaluation of diffusion on metallic film by backside SIMS Evaluation of behavior of impurities by cooling sample (measurement of elements that can cause migration easily) Conditions of channeling of As implanted wafers Evaluation of impurities in low-pressure CVD-SiN films Evaluation of concentration of B in MOS transistors In-depth distribution of Cu wiring structure Backside SIMS of polymetal gate

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