Separate cobalt-copper interface smoothening under the action of low-energy argon ion bombardment

Multilayer film structures of the types buffer gold layer (20 nm)-copper (x nm)-cobalt (y nm)-protective gold layer (10 nm) and buffer gold layer (20 nm)-cobalt (y nm)-copper (x nm)-protective gold layer (10 nm) with x + y approximate to 6 nm obtained by ion beam deposition in vacuum were studied. It was established that the smoothest surface is obtained for a structure of the second type in which the cobalt layer prior to copper deposition was additionally irradiated with a beam of argon ions at an energy below the threshold energy of sputtering in the common vacuum deposition cycle. Additional irradiation with a mixture of argon and helium ions under analogous conditions leads to the formation of a less smooth structure. It is concluded that the cobalt-copper interface is smoothened as a result of multiple collisions of the low-energy argon ion with cobalt atoms during the former ion stopping within two to three of uppermost atomic layers of the target. (C) 2003 MAIK Nauka/Interperiodica.