Semiconductor device and method of fabricating the same

A semiconductor device, comprising:

• a first stacked structure, wherein the first stacked structure comprises:
• a first substrate;
• transistors formed on the first substrate;
• and
• a plurality of conductive layers disposed on the first substrate and electrically connected to the transistors;
• a second stacked structure bonded to the first stacked structure, wherein the second stacked structure comprises:
• a second substrate;
• a magnetic tunnel junction (MTJ) structure disposed on the second substrate and comprising a free layer, a tunnel barrier layer and a synthetic antiferromagnet layer, wherein the tunnel barrier layer is located in between the free layer and the synthetic antiferromagnet layer;
• a seed layer located in between the second substrate and the synthetic antiferromagnet layer;
• a conductive line located in between the seed layer and the second substrate;
• a through substrate via disposed in the second substrate and electrically connected to the conductive line;
• and
• a plurality of second conductive layers disposed on the second substrate and electrically connected to the MTJ structure, wherein the plurality of second conductive layers is located in between the first stacked structure and the free layer of the MTJ structure.

A method of fabricating a semiconductor device, comprising:

• forming a first stacked structure, which comprises:
• providing a first substrate;
• forming transistors on the first substrate;
• and
• forming a plurality of conductive layers on the first substrate and electrically connected to the transistors;
• forming a second stacked structure, which comprises:
• providing a second substrate having a through substrate via disposed therein;
• forming a conductive line on the second substrate and electrically connected to the through substrate via;
• forming a seed layer on the second substrate and connected to the through substrate via, wherein the conductive line is located in between the seed layer and the second substrate;
• forming a magnetic tunnel junction (MTJ) structure on the second substrate and over the seed layer, wherein the MTJ structure comprises a free layer, a tunnel barrier layer and a synthetic antiferromagnet layer, and wherein the tunnel barrier layer is located in between the free layer and the synthetic antiferromagnet layer, and the seed layer is located in between the second substrate and the synthetic antiferromagnet layer;
• and
• forming a plurality of second conductive layers on the second substrate and electrically connected to the MTJ structure;
• bonding the second stacked structure to the first stacked structure, wherein after bonding the second stacked structure to the first stacked structure, the plurality of second conductive layers of the second stacked structure is located in between the first stacked structure and the free layer of the MTJ structure.