Abstract
The nanomechanical response and creep behavior of electroless plated copper (Cu) films have been investigated in this research by using a nanoindentation test. The hardness and elastic modulus of the nanostructural Cu films with a large amount of small grains in size of only 5 nm were measured as 1.5 and 120 GPa, respectively. The Cu films deformed elastically at first and then yielded at a stress of 3.3 GPa. Grain-boundary sliding and grain rotation were expected to dominate the deformation of the Cu films. The Cu films showed a creep strain rate of about 5 × 10 -5 s -1 under the nanoindentation test, and the creep strain rate-stress relation exhibited a typical power law expression with a stress exponent of 6.4. The high creep strain rate but low stress exponent of the Cu films implied a fixed creep behavior consisting of grain-boundary sliding and grain rotation by the fast diffusion of Cu atoms through the large amount of grain-boundary. © 2006 Elsevier B.V. All rights reserved.