Nanoscale strain distributions in embedded SiGe semiconductor devices revealed by precession electron diffraction and dual lens dark field electron holography

Abstract

International audienceThe detailed strain distributions produced by embedded SiGe stressor structures are measured at high spatial resolution with high precision, with dual lens dark field electron holography and precession electron diffraction. Shear strain and lattice rotation within the crystalline lattice are observed at the boundaries between the SiGe and Si regions. The experimental results are compared to micromechanical modeling simulations to understand the mechanisms of elastic relaxation on all the modes of deformation at a sub-micron length scale. (C) 2015 AIP Publishing LLC

Strain mapping at nanometer resolution using advanced nano-beam electron diffraction

“…Recently, a resolution of 2.5 nm measured from the full width half-maximum (FWHM) of the beam was demonstrated for strain mapping with PED. 11 The resolution of NBED can be significantly improved using a more convergent beam, 12 and the slow acquisition speeds of conventional CCD cameras can be overcome by using direct electron detectors, 13 but the application of NBED to large fields-ofview has not been demonstrated.…”

Two-dimensional strain mapping in semiconductors by nano-beam electron diffraction employing a delay-line detector

“…As to typical precisions for strain measurements by nano-beam electron diffraction 9,11,12,28,30 our values are nearly an order of magnitude larger. However, one must keep in mind that the present data has partly been acquired more than an order of magnitude faster in comparison to conventional CCDs and that the precisions found here are still a factor of 2 better than in conventional high-resolution TEM.…”

“…For example, Wang et al 28 report the acquisition of 5000 diffraction patterns in 75 min of which only 8 min correspond to the actual illumination of the CCD. Noting that the recording of the present dataset with these settings would have taken 2.5 h instead of 3-6 min, it is obvious that the DLD provides an efficient, simple, and fast principle to overcome read-out limited data acquisition.…”

Strain distributions in carbon-doped silicon nanowires along [110] and [100] investigated by X-ray diffraction

“…Local strains in nanostructures have been extensively studied by Raman spectroscopy, 2,4,8,13,16,17,20,21) microbeam X-ray diffraction, 3,7,9,10,12,14,15,19,23) electron backscattering pattern 16,17) and dark field electron holography. 5,6,18,22) These methods give excellent results with very fine spatial resolution but are not suitable for statistical investigations since local and individual characteristics are emphasized By observing samples with many nanowires periodically arranged within a 1.5 mm × 1.5 mm region with X-rays of sub-millimeter beam width, we obtained statistically averaged characteristics while eliminating the effects of individual nanowire differences, as previously reported. [32][33][34] Previously, we found an indication that [100] nanowires were more relaxed than [110] nanowires by assuming that all nanowires have uniform lattice spacings.…”