Surface treated structure for solder joint

Abstract

On a rear surface of a semiconductor (10), a contact layer (11), a diffusion preventing layer (12) and a solder joint layer (13) are formed, and this solder joint layer (13) is connected to a mount base (15) by a Pb-Sn solder layer (14). The contact layer (11) is formed of a rare earth metal, its silicide or a composite thereof, the diffusion preventing layer (12) is formed of a ferrous metal, and the solder joint layer (13) is formed of a Ni-Au alloy. By forming the diffusion preventing layer (12) using the ferrous metal, a diffusion of tin in a solder is prevented and by the solder joint layer (13) of the Ni-Au alloy, an excellent solder joint property can be maintained to reduce the number of laminated layers. Further, as a surface treated layer of at least one joint member, the Ni-Au alloy is used and by heating the semiconductor substrate via a solder foil in a reducing atmosphere a high airtightness is obtained.

Dependencies are inferred from the claim text.