Semiconductor package

A semiconductor package comprising:

• an upper substrate on a lower substrate, the upper substrate having a first surface and a second surface which are opposite to each other;
• a plurality of semiconductor chips mounted on the first surface of the upper substrate;
• an interconnection layer between the first surface of the upper substrate and the plurality of semiconductor chips, the plurality of semiconductor chips being connected to a plurality of metal interconnection lines in the interconnection layer;
• a mold layer between the second surface of the upper substrate and the lower substrate;
• an insulating layer between the second surface of the upper substrate and the mold layer;
• a buffer layer between the mold layer and the lower substrate, wherein the buffer layer includes a third surface that is in contact with the mold layer and a fourth surface opposite to the third surface of the buffer layer;
• a plurality of bumps disposed between the buffer layer and the lower substrate and connected to the lower substrate;
• a plurality of through-electrodes penetrating the upper substrate, the insulating layer, and the mold layer;
• and
• conductive pads in the buffer layer and adjacent the third surface of the buffer layer,
• wherein each of the plurality of through-electrodes is connected to a corresponding one of the conductive pads,
• wherein the interconnection layer contacts the plurality of through-electrodes,
• wherein each of the plurality of bumps includes a head portion and a pillar portion,
• wherein the pillar portion extends from the head portion into the buffer layer and is connected to a corresponding one of the conductive pads,
• wherein the head portion is connected to the pillar portion and is disposed on the fourth surface of the buffer layer,
• wherein the mold layer includes an insulating material of which a coefficient of thermal expansion is greater than that of the upper substrate, and
• wherein a thickness in a first direction of the mold layer is less than a thickness in the first direction of the upper substrate, and the first direction is perpendicular to the first surface of the upper substrate.