In order to meet the technological requirements for the next generations of p-n junctions, highly promising methods consist of B and C ultra-low energy co-implantation in Ge pre-amorphized Si. We investigated the B diffusion and the activation phenomena occurring during post-annealing of ultra-shallow junctions (USJ) obtained by spike annealing Si samples pre-amorphized by 20 keV Ge and co-implanted with C at 4 keV and B at 500 eV. Isochronal (60 s) post-annealing processes were performed in inert atmosphere (N-2) by rapid thermal annealing (RTA) in the 500-1050 degrees C temperature range. We show that, contrary to what reported in the literature about C-free USJ, no B diffusion occurs up to 900 degrees C, and further B clustering is completely suppressed over the whole investigated temperature range. Moreover we observed an increase of the sheet resistance by increasing the temperature up to 900 degrees C followed by a subsequent decrease, that can be easily interpreted on the basis of B diffusion and segregation in native SiO2 and B cluster dissolution. Finally, we show that C significantly reduces up to two orders of magnitude the diffusion coefficient of B, that in our experiments is present in highly extrinsic conditions. (c) 2006 Elsevier B.V. All rights reserved.
B diffusion and activation phenomena during post-annealing of C co-implanted ultra-shallow junctions
Napolitani E;Mirabella S;Impellizzeri G;
2006
Abstract
In order to meet the technological requirements for the next generations of p-n junctions, highly promising methods consist of B and C ultra-low energy co-implantation in Ge pre-amorphized Si. We investigated the B diffusion and the activation phenomena occurring during post-annealing of ultra-shallow junctions (USJ) obtained by spike annealing Si samples pre-amorphized by 20 keV Ge and co-implanted with C at 4 keV and B at 500 eV. Isochronal (60 s) post-annealing processes were performed in inert atmosphere (N-2) by rapid thermal annealing (RTA) in the 500-1050 degrees C temperature range. We show that, contrary to what reported in the literature about C-free USJ, no B diffusion occurs up to 900 degrees C, and further B clustering is completely suppressed over the whole investigated temperature range. Moreover we observed an increase of the sheet resistance by increasing the temperature up to 900 degrees C followed by a subsequent decrease, that can be easily interpreted on the basis of B diffusion and segregation in native SiO2 and B cluster dissolution. Finally, we show that C significantly reduces up to two orders of magnitude the diffusion coefficient of B, that in our experiments is present in highly extrinsic conditions. (c) 2006 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.