Trans-projected-range gettering of copper in high-energy ion-implanted silicon

Strong gettering of Cu atoms beyond the projected ion range RP has been found in single-crystal Si implanted with P+ and As+ ions at MeV energies. We call this phenomenon the "trans-RP effect". The formation of a separate Cu gettering band below RP, as detected by secondary ion mass spectrometry, indicates the presence of a significant amount of defects therein. These defects are not detectable by transmission electron microscopy and we suggest that they are small interstitial clusters. The amount of Cu atoms gettered beyond RP is, particularly for the P implants, much greater than that in the implanted gettering layer, indicating that the gettering ability of the defects beyond RP is higher than that of the extended defects at RP. A mechanism responsible for their formation and clustering in the trans-RP region is proposed, and an explanation is given of the differences in the results for the P and As implants.