Preparation of CNT-Copper Matrix Composite Films

Copper matrix composite thin films reinforced with multiwall carbon nanotubes (CNT-Cu-MC) have been processed by electroplating on conducting or insulating underlayers on oxidized (100)Si substrates using iron catalyst particles. The nanotubes were grown by thermal or plasma enhanced catalytic CVD process. Enhanced interfacial strength to copper was achieved after covering the CNTs by plasma enhanced atomic layer deposition (PEALD) of a thin Ta-N or Ta-N/Zr-O interlayer. For copper plating a conventional copper electrolyte with additives (Ethone) was applied. The density of CNTs and their growth determine primarily the quality of the composite films. A sufficient dispersion of CNTs in the copper matrix and homogeneous copper plating were obtained for low density of CNTs. The CNT reinforcement changes the microstructure and electrical properties of electroplated copper films. The resistivity of the Cu films increases by multiwall CNT reinforcement as a result of changed microstructure.