We have investigated the diffusion, agglomeration, and reaction at Cu/3C-SiC interface, using soft X-ray emission spectroscopy (SXES) and photoemission electron microscopy (PEEM). By measuring Si Kbeta emission, the diffusion and/or agglomeration of Cu atoms at Cu (60 nm)/3C-SiC interface were found to occur obviously after annealing at 350 degreesC and to be enhanced with increasing annealing temperature. PEEM observations for a Cu (30 nm)/3C-SiC sample indicated that the Cu film began agglomerating at 550 degreesC annealing from the edge of the Cu film on the 3C-SiC substrate. The agglomeration spread from the edge to the middle region of the Cu film with the increase of temperature. At 850 degreesC annealing, the Cu agglomeration was observed in the whole area of the Cu film. The formation Of Cu3Si was found from SXES analysis for Cu/3C-SiC(001) specimens annealed at temperatures higher than similar to850 degreesC, which indicates the agglomerated material observed by PEEM at 850 degreesC is Cu3Si. (C) 2003 Elsevier Science B.V. All rights reserved.