A semiconductor device is provided. The device comprises first semiconductor wafer comprising first BEOL structure disposed on first side of first substrate, the first BEOL structure comprising first metallization layer disposed over the first substrate, second metallization layer disposed over the first metallization layer, first storage device disposed between the first and second metallization layers, and first transistor contacting the first storage device, and a first bonding layer disposed over the first BEOL structure. The device also comprises second semiconductor wafer comprising second BEOL structure disposed on first side of second substrate, the second BEOL structure comprising third metallization layer disposed over the second substrate, fourth metallization layer disposed over the third metallization layer, second storage device disposed between the third and fourth metallization layers, and second transistor contacting the second storage device, and second bonding layer disposed over the second BEOL structure and contacting the first bonding layer.