Electroless- and Electroplating of Cu(Re) Alloy Films for Self-Forming Ultrathin Re Diffusion Barrier. Issue 3 (1st January 2015)

• Record Type: Journal Article
• Authors: Chang, Shou-Yi; Liang, Li-Ping; Kao, Lin-Chieh; Lin, Chia-Feng
• Is Part Of: Journal of the Electrochemical Society. Volume 162:Issue 3(2015)
• Page Start: D96
• Page End: D101
• Publication Date: 2015-01-01
• Subjects: Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0361503jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : To inhibit the detrimental diffusion of copper into silicon devices, an effective barrier is strongly demanded. In this study, copper(rhenium) alloy films were successfully electroless- and electroplated on silicon substrates for self-forming an ultrathin rhenium barrier layer. In pure copper films, the interdiffusion of copper and silicon already occurred at 400°C, forming silicides and increasing the electrical resistivity of the films. In comparison, not any silicide formation was observed in the electroless- and electroplated copper(rhenium) alloy films with minor incorporations of rhenium for 0.10 and 0.39 at% until 600 and 500°C, respectively, attributed to the prior segregation of rhenium and the self-formation of rhenium barrier layer at the copper/silicon interface at 400°C. A zero solubility of rhenium in copper and a small solubility in palladium catalysts facilitate the separation of rhenium from copper. The kinetics of rhenium segregation follows uphill diffusion, and the diffusivity of rhenium in copper at 400°C is estimated to be 1.5 × 10 −17 cm 2 /s.