Interface characterization of a Cu–Ti-coated diamond system

• A Cu–Ti–diamond system is produced by coating Cu/Ti layers onto diamond particles.
• Interface structure in the system is investigated by Auger electron spectroscopy.
• Compound phases are formed between the Cu and Ti layers.
• This route avoids the challenging fabrication of TEM foils.

Diamond particles dispersed metal matrix composites such as Cu/diamond composites are desirable packaging materials for microelectronic devices because of their potentially high thermal conductivity. The thermal resistance at the metal/diamond interface, however, hinders the development and application of the composites. A Ti coating on diamond particles is proved to enhance the thermal conductivity of Cu/diamond composites. So far the interfaces between diamond particle and Ti layer as well as between Ti layer and Cu matrix have not been clearly identified. This paper aims to study the microstructure of the two interfaces via a Cu–Ti-coated diamond system. Synthetic single-crystalline diamond particles were firstly coated with metallic Ti by using a molten-salt method, and then magnetron sputtering was used to deposit a Cu layer onto the Ti-coated diamond particles. The Cu–Ti-coated diamond particles were heated at 1073 K for 30 min in vacuum to simulate the actual processing of the Cu/diamond composites. Auger electron spectroscopy (AES) results show that TiC is formed between the diamond particle and the Ti layer. Between Ti and Cu layers, Cu was found to diffuse into the Ti layer and to create a compound phase at the Ti/Cu interface. The finding provides an experimental basis for the interface design and production of the Cu/diamond composites.