Si<SUB>3</SUB>N<SUB>4</SUB>, SiC, Al<SUB>2</SUB>O<SUB>3</SUB>/Cu Bonding with Utilizing Mo Metallization of Ceramics by means of Ion Beam Dynamic Mixing

Molybdenum metallization of Si3N4 SiC and Al2O3 substrates for metal-ceramic bonding was performed using an ion beam dynamic mixing method. In this method, a cylindrical ceramic substrate 5 mm in diameter and 5 mm in length was irradiated simultaneously with a 8.0×10−15 J (50 keV), 1-2×105 μA/m2 Ti+ ion beam and a Mo molecular beam at a substrate temperature of 573 K. The substrate metallized with a Mo film 2-5 μm in thickness was bonded to a copper pin 2.5 mm in diameter with an amorphous Cu-9Ni-4Sn-7P solder at 973 K in a depressurized Ar gas atmosphere. Tensile strength of the copper/ceramic joint was determined by a universal testing machine. A strong joint of more than 120 MPa for each ceramic could be obtained.Compared to sputtering as a metallization technique, the dynamic mixing resulted in a joint of superior tensile strength and allowed greater versatility in selection of the chemical type of ceramic substrate. With regard to the chemical type of ion beam used for the dynamic mixing, an active metal ion beam such as Ti+ was found to be much more effective in obtaining a strong joint than an inert gas ion beam like Ar+.The ceramic-metal interface region of the Mo-coated Si3N4 or SiC was observed using a high resolution TEM and an XPS. There were differences between the two ceramics in damage and amorphisation of the ceramic crystal grains caused by the high energy Ti+ ion beam. An amorphous layer, composed of the implanted Ti, the evaporated Mo and some of the ceramic’s constituent elements, was observed in both interface regions. In addition, a precipitated TiN crystal was detected in the Si3N4 system.