PROXIMITY GETTERING BY MEV-IMPLANTATION OF CARBON - MICROSTRUCTURE AND CARRIER LIFETIME MEASUREMENTS

The gettering efficiency of silicon implanted with carbon at a dose of 1 x 10(16) cm-2 and energies in the range of 0.33-10 MeV was tested by carrier lifetime measurements. After an intentional contamination of the sample back side with gold as a lifetime killer, on the front side we found values for the generation lifetime of the minority carriers in the range of 27-78-mu-s and 144-159-mu-s for the 2.4 MeV and 10 MeV implantation, respectively. These values are higher by 1-2 orders of magnitude as compared to unimplanted silicon. Furthermore, an anomalous doping effect of carbon was found which depends on the annealing method (furnace, RTA). The microstructure of the carbon-implanted layer was investigated by electron microscopy of cross-sectional samples showing dislocation loops which surround the stacking faults. These defects are located within a band of very small precipitates.