Semiconductor device stack-up with bulk substrate material to mitigate hot spots

Embodiments disclosed herein include semiconductor dies and methods of forming such dies. In an embodiment, the semiconductor die comprises a semiconductor substrate, an active device layer in the semiconductor substrate, where the active device layer comprises one or more transistors, an interconnect layer over a first surface of the active device layer, a first bonding layer over a surface of the semiconductor substrate, a second bonding layer secured to the first bonding layer, and a heat spreader attached to the second bonding layer.