Abstract

In the DBC (direct bonding of copper) process the oxygen partial pressure surrounding the AlN/Cu bonding pairs has been controlled by Ar gas mixed with oxygen. However, the direct bonding of Cu with sound interface and good adhesion strength is complicated process due to the difficulty in the exact control of oxygen partial pressure by using Ar gas. In this study, we have utilized the in-situ equilibrium established during the reaction of 2CuOrightarrowCu_2O + 1/2 O_2 by placing powder bed of CuO or Cu_2O around the Cu/AlN bonding pair at 1065sim1085°C. The adhesion strength was relatively better in case of using CuO powder than when Cu_2O powder was used. Microstructural analysis by optical microscopy and XRD revealed that the interface of bonding pair was composed of Cu_2O, Cu and small amount of CuO phase. Thus, it is explained that the good adhesion between Cu and AlN is attributed to the wetting of eutectic liquid formed by reaction of Cu and Cu_2O.

• Keywords: Direct bonding of Cu and AlN;Cu-oxides bed;Heat treatment;Microstructure;