Chip-to-chip stacking by using nickel tin metallization stack and diffusion soldering

The invention discloses a chip-to-chip stack realized by using a nickel tin metallization stack and diffusion welding. A method for manufacturing a semiconductor device includes: providing a substrate layer stack including a substrate having a metal upper surface, a first Ni-containing layer disposed on the substrate, and a first Sn layer (110) on the first Ni-containing layer; depositing a first semiconductor layer stack on the first Sn layer, the first semiconductor layer stack comprising: a first NiP layer, a first semiconductor die disposed on the first NiP layer, and a second NiP layer (120) disposed on the first semiconductor die; depositing a second semiconductor layer stack on the first semiconductor layer stack, the second semiconductor layer stack comprising: a second Sn layer, a second Ni-containing layer disposed on the second Sn layer, and a second semiconductor die (130) disposed on the second Ni-containing layer; and performing a diffusion bonding process (140) for connecting the first semicond