SUPPRESSION OF SILICIDE FORMATION IN TA SI SYSTEM BY ION-BEAM-ASSISTED DEPOSITION/

In order to increase the failure temperature of a Ta diffusion barrier for Cu, the suppression of silicide formation in a Ta/Si system by io n-beam-assisted deposition of Ta film was investigated. When the Ta la yer was deposited without ion bombardment, the reaction between Ta and Si started at 600 degrees C. In the case where the Ta film was prepar ed with concurrent ion bombardment, however, the silicide formation wa s retarded up to 700 degrees C. The suppression of Ta silicide formati on can be attributed to a densification of grain boundaries in the Ta film by ion bombardment, followed by a reduction of the chemical drivi ng force for the initial stage of silicide formation. The Ta diffusion barrier deposited by ion-beam-assisted deposition effectively suppres sed the reaction between Si and Cu layers up to 650 degrees C for 30 m in. (C) 1997 American Institute of Physics. [S0003-6951(97)01043-7].