Semiconductor package and method of fabricating the same

A method of fabricating a semiconductor package, the method comprising:

• providing a semiconductor substrate extending in a first direction and a second direction, perpendicular to the first direction, the semiconductor substrate having an active surface and an inactive surface that is opposite to the active surface;
• forming a transistor on the active surface of the semiconductor substrate;
• forming through vias in the semiconductor substrate, the through vias extending from the active surface into the semiconductor substrate, the through vias each including a first end that faces the inactive surface and is covered by a corresponding portion of the semiconductor substrate;
• then, forming a first pad layer on the active surface of the semiconductor substrate;
• then, performing a first planarization process comprising planarizing the first pad layer including removing material from the first pad layer;
• then, thinning the semiconductor substrate by performing on the inactive surface of the semiconductor substrate a thinning process including removing semiconductor material from the inactive surface to uncover and expose the first ends of each of the through vias;
• then, forming a second pad layer on the inactive surface of the semiconductor substrate;
• then, performing a second planarization process comprising planarizing the second pad layer including removing material from the second pad layer;
• and
• after the second planarization process, performing a third planarization process comprising planarizing the first pad layer including removing material from the first pad layer.