Methods of forming a semiconductor package (2, 12) are provided. Implementations include forming on a die backside (16) an intermediate metal layer (26) having multiple sublayers (40-46), each including a metal selected from the group consisting of titanium, nickel, copper, silver, and combinations thereof. A tin layer (48) is deposited onto the intermediate metal layer (26) and is then reflowed with a silver layer (52) of a substrate (50) to form an intermetallic layer (56) having a melting temperature above 260 degrees Celsius and including an intermetallic consisting of silver and tin and/or an intermetallic consisting of copper and tin. Another method of forming a semiconductor package includes forming a bump (22) on each of a plurality of exposed pads (20) of a top side (18) of a die (14), each exposed pad (20) surrounded by a passivation layer (24), each bump (22) including an intermediate metal layer (36) as described above and a tin layer (48) coupled to the intermediate metal layer (36), the tin layer (48) being then reflowed with a silver layer (52) of a substrate (50) to form an intermetallic layer (64), as described above.