Semiconductor device, semiconductor device package, and manufacturing methods thereof

A method of manufacturing a semiconductor device, the method comprising, in this order:

• preparing a bottom plate having an upper surface and a lower surface, wherein the upper surface comprises an outer peripheral part and an inside part that is enclosed by the outer peripheral part and that protrudes more upward than the outer peripheral part, wherein a thickness of the bottom plate at the inside part is greater than a thickness of the bottom plate at the outer peripheral part, and wherein the lower surface of the bottom plate comprises a reference part and a recess positioned above the reference part, at least a part of the recess being disposed directly below the outer peripheral part;
• joining a frame member to the outer peripheral part of the bottom plate, a linear expansion coefficient of the frame member being smaller than a linear expansion coefficient of the bottom plate;
• and
• fixing a semiconductor element to the inside part of the bottom plate,
• wherein a depth of the recess in the step of fixing the semiconductor element is smaller than a depth of the recess in the step of preparing the bottom plate, due to warpage that occurs in the bottom plate during the step of joining the frame member.