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27 August 1997 Low-energy BF2, BCl2, and BBr2 implants for ultrashallow P+-N junctions
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We have examined low energy BCl2 and BBr2 implants as a means of fabricating ultra-shallow P+-N junctions. Five keV and 9 keV BCl2 implants and 18 keV BBr2 implants have been compared to 5 keV BF2 implants to study the benefits of using these species. BCl2 and BBr2, being heavier species, have a lower projected range and produce more damage. The greater damage restricts channeling, resulting in shallower as-implanted profiles. The increased damage amorphizes the substrate at low implant doses which results in reduced transient enhanced diffusion (TED) during the post-implant anneal. Post-anneal SIMS profiles indicate a junction depth reduction of over 10 nm (at 5 X 1017 cm-3 background doping) for 5 keV BCl2 implants as compared to 5 keV BF2 implants. Annealed junctions as shallow as 10 nm have been obtained from the 18 keV BBr2 implants. The increased damage degrades the electrical properties of these junctions by enhancing the leakage current densities. BCl2 implanted junctions have leakage current densities of approximately 1 (mu) A/cm2 as compared to 10 nA/cm2 for the BF2 implants. BBr2 implants have a lower leakage density of approximately 50 nA/cm2. Low energy BBr2 implants offer an exciting alternative for fabricating low leakage, ultra-shallow P+-N junctions.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. Raghu Nandan, Vikas Agarwal, and Sanjay K. Banerjee "Low-energy BF2, BCl2, and BBr2 implants for ultrashallow P+-N junctions", Proc. SPIE 3212, Microelectronic Device Technology, (27 August 1997); doi: 10.1117/12.284586;

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