Strain measurement for the semiconductor industry with nm-scale resolution by dark field electron holography and nanobeam electron diffraction

Dark field electron holography and Nanobeam electron diffraction (NBED) are two recently developed techniques that can be used to measure strain in semiconductor specimens with nm-scale resolution. Here we discuss the basics of these techniques and show how they have been applied to recessed source and drain SiGe device specimens in order to observe the strain in the channel region as a function of gate length and germanium content. We also show how these techniques have been used to observe the evolution of strain in devices during the salicidation process. Finally we discuss the advantages and disadvantages of using each technique.