ION BEAM INDUCED INTERMIXING OF WSi sub (0.45) on GaAs.

The systematics of ion beam induced intermixing of WSi sub (0.45) on GaAs have been studied after through-implantation of Si or O in the dose range 10 sup (13) - 5 x 10 sup (16) cm sup (-2). SIMS profiling shows significant knock-on of Si and W into the GaAs at the high dose range in accordance with Monte Carlo simulations, but there is virtually no electrical activation (=0.1%) of this Si after normal implant annealing (900C, 10 sec). This appears to be a result of the high level of disorder near the metal-semiconductor interface, which is not repaired by annealing. This damage consists primarily of dislocation loops extending a few hundred angstroms below the end of range of the implanted ions. Extrapolation of the ion doses used in this work to the usual doses used in GaAs device fabrication would imply that ion-induced intermixing of WSi sub x will not be significant in through-implantation processes.