The RP/2 EffectBy high-energy ion implantation a damage is created in the whole depth range from the wafer surface to ~ RP + D RP (mean projected range: RP). Despite of damage annealing at T= 900oC strong impurity gettering has been detected at depths between the surface and RP [1-4] This is called the RP/2 effect. The size of the defects responsible for the gettering at RP/2 is below the resolution limit of transmission electron microscopy (TEM). They are very small defect clusters.
Recently we have reported  that defects at RP/2
can be observed by TEM. TEM observations for a specific ion milling procedure
reveal the presence of interstitial-type loops (Fig. 1).
(a) SIMS Cu depth profile for FZ-Si after FA at 850°C/1h. correlated with the concentration of self-interstitials bound in loops (bars);
(b, c, d, e) XTEM bright field micrographs. The sample is the same as in (a).The incidence angle for milling is 13° (b), 15° (c), 17° (d) and 4° (e). The bar in the micrographs corresponds to 200 nm.
These loops appear by injection of self-interstitial atoms during ion milling process (Fig. 2).
A scheme of a cross-sectional sample, milling incidence angle.
Results of our study:
The interstitials caused by the ion milling procedure modify significantly
the defect structure of previously MeV self-ion-implanted and annealed
The interstitial loops appear only in the RP/2 region. The presence of copper in the sample does not play role in the formation of the defects during milling .
The real gettering centres for Cu atoms at RP/2 are suggested  be self-interstitial clusters, too small to be visible by XTEM.
 R. Kögler, D. Panknin, W. Skorupa, P.
Werner, and A. Danilin
Proc. of the XI Int. Conf. Ion Implantation and Technology 96, IEEE Publ. 96TH8182, Piscataway, NJ 08854-4150.
 R.Kögler, M.Posselt, R.A. Yankov, J.R. Kaschny, P. Werner,
A.B. Danilin, and W. Skorupa
Mat. Res. Symp. Proc. Vol. 469, 463 (1997)
 A. Peeva, R.Kögler, G. Brauer, W. Skorupa, and P.Werner
1st ENDEASD Workshop Proc. p. 269, Santorini April 1999, Greece
 R.Kögler, A. Peeva, W. Anwand, G. Bauer, P. Werner, W. Skorupa,
and U. Gösele
Appl. Phys. Lett. 75, 1279 (1999)