Articles you may be interested inConvergent beam electron diffraction measurements of relaxation in strained silicon using higher order Laue zone line splitting J. Appl. Phys. 105, 063526 (2009); 10.1063/1.3093693 Convergent beam electron diffraction investigation of strain induced by Ti self-aligned silicides in shallow trench Si isolation structures J. Appl. Phys. 99, 064504 (2006); 10.1063/1.2179136 Strain analysis in silicon substrates under uniaxial and biaxial stress by convergent beam electron diffraction J. Vac. Sci. Technol. B 23, 940 (2005); 10.1116/1.1924583Determining the relationship between local lattice strain and slip systems of dislocations around shallow trench isolation by convergent-beam electron diffraction Test structures consisting of shallow trench isolation ͑STI͒ structures are fabricated using advanced silicon ͑Si͒ technology. Different process parameters and geometrical features are implemented to investigate the residual mechanical stress in the structures. A technology computer aided design homemade tool, IMPACT, is upgraded and optimized to yield strain fields in deep submicron complementary metal-oxide-semiconductor devices. Residual strain in the silicon substrate is measured with micro-Raman spectroscopy ͑-RS͒ and/or convergent beam electron diffraction ͑CBED͒ for large ͑25 m͒ and medium size ͑2 m͒, while only CBED is used for deep submicron STI ͑0.22 m͒. We propose a methodology combining CBED and technology computer aided design ͑TCAD͒ with -RS to assess the accuracy of the CBED measurements and TCAD calculations on the widest structures. The method is extended to measure ͑by CBED͒ and calculate ͑by TCAD͒ the strain tensor in the smallest structures, out of the reach of the -RS technique. The capability of determining, by both measurement and calculation, the strain field distribution in the active regions of deep submicron devices is demonstrated. In particular, it is found that for these structures an elastoplastic model for Si relaxation must be assumed.

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The deformation induced onto silicon by the formation of Ti self-aligned silicides (salicides) in shallow trench isolation structures has been investigated by the convergent beam electron diffraction technique (CBED) in the transmission electron microscope (TEM). The splitting of the high order Laue zone (HOLZ) lines in the CBED patterns taken in TEM cross sections close to the salicide/silicon interface has been explained assuming that the salicide grains induce a local bending of the lattice planes of the underlying matrix. This bending, which affects in opposite sense the silicon areas below adjacent grains, decreases with the distance from the interface, eventually vanishing at a depth of 300–400nm. The proposed strain field has been implemented into a fully dynamical simulation of the CBED patterns and has proved to be able to reproduce both the asymmetry of the HOLZ line splitting and the associated subsidiary fringes. This model is confirmed by the shift of a Bragg contour observed in large angle CBED patterns, taken in a cross section cut along a perpendicular direction. The whole experimental results cannot be explained by just a strain relaxation of the TEM cross section, induced by the salicide film onto the underlying silicon.