Activation and dopant sites of ultra-shallow implanted boron and arsenic in silicon

Individual Atomic Imaging of Multiple Dopant Sites in As-Doped Si Using Spectro-Photoelectron Holography

“…As such, an understanding of the atomic structures of dopants in semiconductors would assist in the development of new process technologies for the fabrication of high-performance devices. For this reason, atomic level dopant structures have been investigated using both theoretical and experimental approaches, − although the direct observation of the three-dimensional (3D) structures of dopant arrangements has been difficult to achieve. X-ray diffraction (XRD) and electron diffraction are powerful methods of visualizing 3D atomic structures; however, these techniques are only applicable to crystalline structures and cannot be applied to the visualization of dopant structures because the dopants are not dispersed with a regular periodicity in the crystal.…”

“…X-ray diffraction (XRD) and electron diffraction are powerful methods of visualizing 3D atomic structures; however, these techniques are only applicable to crystalline structures and cannot be applied to the visualization of dopant structures because the dopants are not dispersed with a regular periodicity in the crystal. X-ray absorption fine structure (XAFS) can provide information regarding dopants, although only with respect to the atomic distance. ,, In addition, ion scattering can be used to detect the positions of target atoms relative to crystalline matrix channels. − High-resolution scanning transmission electron microscopy (STEM) has also been used to image individual dopant atoms in real space and has provided data regarding the formation of dopant clusters. , The determination of the 3D structure of the dopant has also been attempted . In principle, however, direct imaging for light elements or cases involving vacancies is difficult.…”

Thermal activation of As implanted in bulk Si and separation by implanted oxygen

“…The FA samples show a more pronounced effect due to the longer annealing time, which allows the formation of a larger number of these complexes. For longer annealing times the As n V complex concentration increases as well as the As fraction in them, which means increasing n. 10 As mentioned previously, 11 As atoms are electrically inactive when bound to a vacancy. This dopant deactivation process is most significant after the implantation damage has been removed by annealing and when the dopants start to form complexes with vacancies and clusters.…”

“…This dopant deactivation process is most significant after the implantation damage has been removed by annealing and when the dopants start to form complexes with vacancies and clusters. 10,11 Another interesting feature is the lower damage level in the SIMOX samples after RTA compared to bulk Si, as can be seen in the RBS channeled spectrum of the As peak in Fig. 2(a).…”

“…In other words, the diffusion of all As atoms closer than the ninth neighbor will be affected by the presence of that AsV complex. Experiments suggest that a large fraction of electrically inactive As atoms are either in substitutional lattice sites in the form of As clusters, 11 or, for high dopant concentrations, coherent crystalline precipitates. 12,13 The latter are expected to be present both in bulk Si and SIMOX, although the clusters containing vacancies should be favored in SIMOX compared to bulk Si due to the higher vacancy concentration in this type of substrate.…”