GETTERING OF CU BY HE-INDUCED CAVITIES IN SIMOX MATERIALS

Gettering of Cu impurities to He-implantation induced cavities in sepa ration by implantation of oxygen (SIMOX) materials has been investigat ed by means of cross-sectional transmission electron microscopy and se condary ion mass spectroscopy. The cavities were introduced beneath th e buried oxide layer (BOX) in SIMOX substrates by He+ implantation (9 x 10(16)/cm(2), 60 keV) and subsequent annealing. The results indicate that these cavities are strong gettering sites for Cu impurities whic h have been implanted into the top Si layer of SIMOX. After a 1000 deg rees C annealing, 80% of the initially implanted Cu impurities in the top layer have diffused through the buried oxide layer to be captured by the cavities. The gettering effect of these He-induced cavities is much stronger than the damage region beside the BOX. The buried oxide in SIMOX does not appear to prevent the movement of Cu at 1000 degrees C. He+ implantation-induced cavity has been demonstrated to he an att ractive method to remove Cu impurities away from the top Si layer in S IMOX wafers. (C) 1998 Elsevier Science B.V.