Die stacking structure and fabricating method thereof

A fabricating method of a die stacking structure, comprising:

• forming a first conductive via on a first die, wherein the first conductive via passes through the first die, the first conductive via comprises a first pad and a second pad, the first pad is located at a first side of the first die, the second pad is located at a second side of the first die, and the first pad and the second pad are partially or totally overlapped in a vertical direction of the first die;
• forming a second conductive via on the first die, wherein the second conductive via passes through the first die, the second conductive via comprises a third pad and a fourth pad, the third pad is located at the first side of the first die, the fourth pad is located at the second side of the first die, and the third pad and the fourth pad are partially or totally overlapped in the vertical direction of the first die;
• forming a fifth pad at the first side of the first die;
• forming a sixth pad at the second side of the first die, and the sixth pad and the fifth pad are partially or totally overlapped in the vertical direction of the first die;
• forming a seventh pad at the first side of the first die;
• and
• forming an eighth pad at the second side of the first die, and the eighth pad and the seventh pad are partially or totally overlapped in the vertical direction of the first die;
• forming a first wire at the first side of the first die, wherein the first pad and the seventh pad are directly connected by the first wire;
• forming a second wire at the second side of the first die, wherein the second pad and the sixth pad are directly connected by the second wire;
• forming a third wire at the first side of the first die, wherein the third pad and the fifth pad are directly connected by the third wire;
• forming a fourth wire at the second side of the first die, wherein the fourth pad and the eighth pad are directly connected by the fourth wire:
• forming at least four pads at one side of a second die;
• and
• selectively forming at least one first conductive bump between at least one of the first to the eighth pads of the first die and the pads of the second die, so as to conduct at least one of the first to the eighth pads of the first die and the pads of the second die.