Method of fabricating a semiconductor package

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

• providing a package substrate including a pad;
• mounting a semiconductor chip with a solder ball on the package substrate to allow the solder ball to be disposed on the pad;
• filling a space between the package substrate and the semiconductor chip with an underfill resin, the underfill resin including a reducing agent comprising a carboxyl group;
• irradiating the semiconductor chip with a laser to bond the solder ball to the pad, the bonding of the solder ball to the pad including changing a metal oxide layer formed on surfaces of the pad and the solder ball to a metal layer due to heat generated by the laser;
• and
• after the bonding of the solder ball to the pad,
• forming another underfill resin on the semiconductor chip to cover a chip pad disposed on an upper surface of the semiconductor chip;
• mounting another semiconductor chip with another solder ball on the semiconductor chip;
• applying heat to the package substrate to decrease viscosity of the another underfill resin and aligning the another semiconductor chip with the semiconductor chip to allow the another solder ball to be disposed on the chip pad;
• and
• bonding the another solder ball to the chip pad by using heat generated by laser irradiated to the another semiconductor chip.