A device assembly structure includes a first device and at least one second device. The first device has a first active surface and a first backside surface opposite to the first active surface, and includes a plurality of first electrical contacts disposed adjacent to the first active surface. The second device has a second active surface and a second backside surface opposite to the second active surface, and includes a plurality of second electrical contacts disposed adjacent to the second active surface. The second active surface of the second device faces the first active surface of the first device, the second electrical contacts of the second device are electrically connected to the first electrical contacts of the first device, and a thickness of the second device is less than or equal to one fifth of a thickness of the first device.