As the lower fin FNB is provided in the second enclosure 122_1, the surface area of the second enclosure 122 may be enlarged. When the surface area of the second enclosure 122_1 is enlarged, the heat capacity may increase.
Also, an additional space as a result of the protruding height of the lower fin FNB is generated above the lower fin FNB of the second enclosure 122_1. When the thermal gap filler GFL_H related to the heat capacity is filled in the additional space, the entire heat capacity of the memory device can be further increased.
In this embodiment, the height of the memory device may be increased by the sum of the protruding heights of the upper fin FNU and the lower fin FNB. If the height increase of the memory device by the fins FNU and FNB needs to be designed to about 6.5 mm as in the embodiments of