Synthesis of nano-sized SiC precipitates in Si by simultaneous dual beam implantation of C+ and Si+ ions

Nanometer-sized SiC precipitates were in-situ synthesized in Si by simultaneous implantation of two ion beams, of C+ and Si+ ions. The results of simultaneous dual beam implantation were compared with those of sequential dual beam ion implantation and of single beam C+ ion implantation. Remarkable differences were observed regarding the content and the crystal perfection of SiC precipitates as well as the defect structure of the Si substrate. The SiC precipitation during dual beam synthesis was found to depend on the ion energy of the second beam and on the implantation mode, simultaneous or sequential. For suitable implantation conditions the simultaneous dual beam synthesis can improve the in-situ SiC formation in comparison to the single beam synthesis. A higher density of the SiC precipitates with better crystal perfection was observed whereas their size was not changed. The second ion beam enables to shift the dynamic equilibrium of constructive and destructive processes for the SiC formation.
A model is proposed assuming that SiC precipitation preferentially proceeds in regions with vacancy defects. The implantation process itself creates vacancy-dominated and also interstitial-dominated regions. The balance of the local point defect composition is shifted under the second ion beam. In this way the conditions for SiC precipitation can be modified.