Patent ID: 8901751

Claim:
A semiconductor device, comprising: a first connection member that includes a first connection pad formed on a first principal surface of the first connection member; a fast semiconductor chip that includes a circuit-formed surface on which a semiconductor integrated circuit is formed and a second connection pad formed on the circuit-formed surface, the fast semiconductor chip mounted on the first connection member in such a manner that the circuit-formed surface faces the first principal surface; and a solder bump that connects the first connection pad to the second connection pad and is made of metal containing Bi and Sn, wherein the solder bump includes a first interface layer containing a Cu—Sn alloy and formed adjacent to the second connection pad, a second interface layer containing a Cu—Sn alloy and formed adjacent to the first connection pad, a first intermediate region formed adjacent to and in direct contact with either one of the first interface layer or the second interface layer, and a second intermediate region formed adjacent to and in direct contact with the other one of the first interface layer and the second interface layer and formed adjacent to the first intermediate region; a concentration of Bi in the first intermediate region is higher than a concentration of Sn in the first intermediate region; and a concentration of Sn in the second intermediate region is higher than a concentration of Bi in the second intermediate region.