Evaluation of two-dimensional strain distribution by STEM/NBD

We proposed a strain mapping technique by Nano Beam electron Diffraction (NBD) combined with an energy filter (EF) and a scanning transmission electron microscopy (STEM) function. The STEM function improves the accuracy of a position where a diffraction pattern is acquired. The EF excludes inelastic scattering and enables novel numerical processing for the appropriate measurement of distances between diffraction disks. Using this technique, strain distributions were measured for two different types of p-MOSFETs, i.e., source/drain regions of each MOSFET is composed of different types of silicide, and the difference of their strain distributions in the channel region was confirmed. The proposed method was able to clarify that the strain distributions are quite different depending on the silicide materials even if the exterior of the MOSFETs was almost identical.