Influence mechanism of magnetron sputtering process parameters on diamond surface preprocessing interface for chip heat sink

Abstract

The interface between diamond and aluminum is poor in wettability and solid solubility. The interface bonding can be improved effectively by plating metal elements on diamond surface combined with heat treatment. In this paper, the influence of adjustable process parameters on the quality of Mo layer modified by magnetron sputtering was studied based on orthogonal experiments, and Mo-coated diamond/aluminum composite materials were prepared by Spark Plasma Sintering (SPS). The results indicate that the deposition of Mo layer on the diamond surface proceeds through three stages: adsorption, surface diffusion, and stable nucleus growth, forming an initial thin film, followed by layer-by-layer stacking through repeated growth of these stages. Sputtering time and sputtering pressure are the main factors affecting the quality of the coating. Mo layers prepared under conditions of 30 min and 0.5 Pa exhibit uniform and dense surface and moderate thickness. After heat treatment, recrystallization forms equiaxed grains, and Mo₂C is formed in reaction with diamond, effectively enhancing the interface bonding strength between diamond and aluminum. The thermal conductivity of the diamond/aluminum composite material reached 342 W/(mK).