Influence of titanium on the formation of a “barrier” layer during joining an A1N ceramic with copper by the CDB technique

Abstract

The paper presents the results concerning the formation of a ‘barrier’ layer on AlN ceramic during its joining with copper by the Copper Direct Bonding (CDB) technique. The surface of the ceramic was modified with titanium, using various amounts of this active component. When deposited by sputtering, Ti layers were about 0.35 μm thick. The implantation doses were 1 × 1016, 5 × 1016, 2 × 1017 and 1 × 1018 ions/cm2, and the ions were accelerated by a voltage of 70 or 15 kV. The modified ceramic was joined with oxidized copper in a nitrogen atmosphere with about 1.5 ppm of oxygen using a belt-type furnace. The results of the examinations of the mechanical strength of the joints and of the microstructural and phase changes induced on the surfaces of the joints during the bonding process formed the basis for establishing the optimum conditions of modification of the AlN surface with titanium ions by introducing them just beneath the surface layer of the ceramic. The modification yielded a multiphase ‘barrier’ layer, which ensured a continuous pore-less contact between the materials being joined. The joints thus produced showed a high mechanical strength. Optimum conditions were also established for joining the AlN ceramic directly with copper by the CDB technique in a nitrogen atmosphere.