New Bonding Technique Using Copper Oxide Materials

As a bonding technique between semiconductor elements in a semiconductor device and external substrates, a reduction bonding technique has been developed that uses CuO particles several micrometers large. This technique has the following features. (1) CuO particles can be reduced in about 200 degrees C H-2 atmosphere. (2) Pure Cu particles about 50 nm in diameter form at this time. (3) The formed Cu particles form a sintered Cu layer. (4) Bonding can be achieved above 350 degrees C. Bonding requires pressurization. The bonding strength (shear breaking strength) of this sintered Cu layer and Ni electrodes used by many semiconductor devices was evaluated. Consequently, bonding strengths were about 20 MPa at pressurization of 1.2 MPa and a heating temperature of 350 degrees C. Moreover, in the bonded interface of a sintered Cu layer and Ni electrodes, the sintered Cu layer formed the hetero-epitaxial layer between Ni electrodes. For this reason, we confirmed that the bonded interface of a sintered Cu layer and Ni electrodes was in a strong bonding state on the metal object. [