Suppression of Boron Transient Enhanced Diffusion by C Trapping

摘要

In this work the carbon ability to stop Si-interstitials is investigated in detail. We show that a Si_(1-y)C_y layer (y = 0.01 - 0.1 %) located between an interstitial source (produced near the surface by a Si 20 keV implant) and a deep B spike, can intercept the interstitial wind, behaving as a membrane, and can suppress the expected transient enhanced diffusion (TED) in the B spike. In particular, this trapping mechanism is studied as a function of the total carbon dose, and it is shown that a carbon dose equal to the implant dose is able to stop the self-interstitials and suppress the B-TED totally. These results suggest a one-one interaction between the carbon and the self-interstitial in the trapping mechanism. Moreover, experimental evidence for carbon clustering is reported when carbon atoms have trapped Si-interstitials. Finally, an application for the ultra-shallow junctions fabrication is shown, in which a Si_(1-y)C_y layer prevents the B-TED due to the backflow of interstitials from the end of range damage in a preamorphized B-implanted silicon sample.