Patent ID: 8158459

Claim:
A substrate bonding method comprising steps of: (a) forming a first Sn absorption layer on a principal surface of a first substrate, the first Sn absorption layer being made of metal that absorbs Sn from AuSn alloy and lowers a relative proportion of Sn in the AuSn alloy; (b) forming a second Sn absorption layer on a principal surface of a second substrate, the second Sn absorption layer being made of a metal that absorbs Sn from AuSn alloy and lowering a relative proportion of Sn in the AuSn alloy; (c) forming a solder layer made of AuSn alloy at least on one of the first and second Sn absorption layers; and (d) melting the solder layer to bond the first and second substrates together, in a state in which the principal surfaces of the first and second substrates face each other; wherein in step (d), Sn atoms in the solder layer diffuse into the first Sn absorption layer and the second Sn absorption laver, and a metal element of the first Sn absorption layer and second Sn absorption layer is dissolved in the melted solder layer, thereby forming a bonding layer including the first Sn absorption layer, the second Sn absorption layer, and the solder layer, with the metal element distributed across an entire thickness of the bonding layer.