Hitachi, Ltd.

Hisakichi Onodera

Masateru Suwa

Jin Onuki

Ko Soeno

Yoshiteru Shimizu

There is provided a method of fabricating a semiconductor device wherein in a bonding surface of a silicon substrate of n-type conductivity are formed recesses having each a bonding surface of a higher order plane index than that of the bonding surface of the silicon substrate, and the substrate and electrodes and the like members are bonded together with an aluminum solder so as to decrease a forward voltage drop FVD. After forming the recesses but prior to the bonding with the aluminum solder, phosphor is diffused into a region ranging from the bonding surface to a depth of 20 microns, thereby further decreasing the forward voltage drop FVD. When cooling after the bonding, a temperature gradient is established so that temperature in the silicon substrate is higher than a temperature in the molten aluminum so that the forward voltage drop FVD can be decreased further.

Method of fabricating semiconductor device by bonding together silicon

A semi-conductor device comprising a silicon body having an exposed surface of N-type conductivity layer and a substrate bonded to the exposed surface by means of a layer of a new solder material, the solder material being an alloy consisting essentially of 2 to 12% by weight of at least one element of Group V of the periodic table, preferably antimony, and 0.01 to 5% by weight of at least one of rare earth elements, for example, Misch metal and aluminum being balance on the basis of total weight of the solder material. An increase in FVD of the device in which a conventional aluminum solder is used is prevented by the use of the new solder materials.

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Hitachi, Japan

Hisakichi Onodera