DISLOCATION-STRUCTURE IN COARSE-GRAINED COPPER AFTER ION-IMPLANTATION

We have investigated the dislocation structures formed in the near sur face region of ion implanted coarse-grained copper (grain size 460 mu m) using transmission electron microscopy. Ti and Zr ions were implant ed into copper using a vacuum are ion source. The ion energy was about 100 keV and the applied (incident) dose was 1 x 10(17) cm(-2). We fin d that Ti and Zr ion implantations produce a developed dislocation str ucture in the Cu subsurface layers. The dislocation structure changes form cell-net and cell dislocation structures at shallow depth to indi vidual randomly distributed dislocations at greater depth. The maximum dislocation density in copper is 6.1 x 10(9) cm(-2) for Ti and 11.4 x 10(9) cm(-2) for Zr. The thickness of the modified copper layer with high dislocation density is up to 20 mu m for Ti and 50 mu m for Zr. M icrohardness measurements vs. depth and dopant concentration profiles are presented. The long range effect is explained in terms of a model of static and dynamic mechanical stresses formed in the implanted surf ace layer.