Quantitative strain mapping in nano electronic silicon dvices by convergent beam electron diffraction

Lattice deformations which are generated in thedifferent process steps of the current technology fornanoelectronic devices can affect either positively ornegatively their electrical performances. In both casesquantitative information on strains at the nanometerscale are necessary, and presently this can only beachieved by convergent beam electron diffraction(CBED), a technique available in any moderntransmission electron microscope (TEM). In this paper the basic principles of CBED, the method to extract the local strain tensorfrom an experimental diffraction pattern and its application to twodimensional strain mapping in the active silicon region of ultra-scaled isolation structures are reported. The limitations of this method, particularly in the case of high strain gradients along a direction perpendicular to the plane of the device TEM cross section, are discussed. Possible solutions to obtain the displacement field distribution, with reference to a practical case, are described.