A semiconductor device package includes a substrate, a silicon (Si) or silicon carbide (SiC) semiconductor die, and a metal layer on a surface of the semiconductor die. The metal layer includes a bonding surface that is attached to a surface of the substrate by a die attach material. The bonding surface includes opposing edges that extend along a perimeter of the semiconductor die, and one or more non-orthogonal corners that are configured to reduce stress at an interface between the bonding surface and the die attach material. Related devices and fabrication methods are also discussed.