A method of fabricating a semiconductor device, the semiconductor device comprising: a semiconductor element; a support member (3, 5) bonded to a first surface of the semiconductor element with a first bonding member; and a lead electrode bonded to a second surface of the semiconductor element supported on the support member with a second bonding member, and the method comprising: providing a Ni-plating on the first surface of the semiconductor element and the surface of the support member (3, 5) facing the semiconductor element and bonding the first surface of the semiconductor element to the surface of the support member using a Sn solder having a Cu content of 3 to 7% by mass and containing Cu 6 Sn 5 grains as a bonding material, and/or providing a Ni-plating on the second surface of the semiconductor element and the surface of the lead electrode facing the semiconductor element and bonding the second surface of the semiconductor element to the surface of the lead electrode using a Sn solder having a Cu content of 3 to 7% by mass and containing Cu 6 Sn 5 grains as a bonding material, such that: a plated Ni layer and a Cu-Sn compound layer are formed in each of an interface between the support member and the first bonding member and an interface between the first bonding member and the semiconductor element, and/or a plated Ni layer and a Cu-Sn compound layer are formed in each of an interface between the lead electrode and the second bonding member and an interface between the second bonding member and the semiconductor element. a semiconductor element; a support member (3, 5) bonded to a first surface of the semiconductor element with a first bonding member; and a lead electrode bonded to a second surface of the semiconductor element supported on the support member with a second bonding member, and the method comprising: providing a Ni-plating on the first surface of the semiconductor element and the surface of the support member (3, 5) facing the semiconductor element and bonding the first surface of the semiconductor element to the surface of the support member using a Sn solder having a Cu content of 3 to 7% by mass and containing Cu 6 Sn 5 grains as a bonding material, and/or providing a Ni-plating on the second surface of the semiconductor element and the surface of the lead electrode facing the semiconductor element and bonding the second surface of the semiconductor element to the surface of the lead electrode using a Sn solder having a Cu content of 3 to 7% by mass and containing Cu 6 Sn 5 grains as a bonding material, providing a Ni-plating on the first surface of the semiconductor element and the surface of the support member (3, 5) facing the semiconductor element and bonding the first surface of the semiconductor element to the surface of the support member using a Sn solder having a Cu content of 3 to 7% by mass and containing Cu 6 Sn 5 grains as a bonding material, and/or providing a Ni-plating on the second surface of the semiconductor element and the surface of the lead electrode facing the semiconductor element and bonding the second surface of the semiconductor element to the surface of the lead electrode using a Sn solder having a Cu content of 3 to 7% by mass and containing Cu 6 Sn 5 grains as a bonding material, such that: a plated Ni layer and a Cu-Sn compound layer are formed in each of an interface between the support member and the first bonding member and an interface between the first bonding member and the semiconductor element, and/or a plated Ni layer and a Cu-Sn compound layer are formed in each of an interface between the lead electrode and the second bonding member and an interface between the second bonding member and the semiconductor element. a plated Ni layer and a Cu-Sn compound layer are formed in each of an interface between the support member and the first bonding member and an interface between the first bonding member and the semiconductor element, and/or a plated Ni layer and a Cu-Sn compound layer are formed in each of an interface between the lead electrode and the second bonding member and an interface between the second bonding member and the semiconductor element.