Packaging structure and fabrication method thereof

A fabrication method for a packaging structure, comprising:

• providing semiconductor chips, wherein each semiconductor chip includes a functional surface, a non-functional surface opposite to the functional surface, soldering pads on the functional surface, a metal bump on each soldering pad;
• forming a first plastic encapsulation layer on functional surfaces of the semiconductor chips and covering metal bumps of the semiconductor chips;
• adhering the first plastic encapsulation layer on the functional surfaces of the semiconductor chips to a carrier plate;
• forming a first shielding layer covering non-functional surfaces and sidewalls of the semiconductor chips;
• forming a second shielding layer on the first shielding layer;
• forming a second plastic encapsulation layer on the second shielding layer and on a portion of the carrier plate between semiconductor chips;
• peeling off the carrier plate to form a pre-packaging plate, wherein a backside of the pre-packaging plate exposes the first plastic encapsulation layer;
• removing a portion of the first plastic encapsulation layer to expose metal bumps;
• and
• forming an external contact structure on the backside of the pre-packaging plate and connected to each metal bump, wherein:
• a thickness of the first shielding layer is equal to a thickness of the first plastic encapsulation layer on top surfaces of the metal bumps;
• and
• a portion of the first plastic encapsulation layer is removed by a polishing process to expose the metal bumps, and a portion of the first shielding layer between the semiconductor chips is removed simultaneously to make surfaces of the metal bumps flush with a surface of the second plastic encapsulation layer, a surface of a remaining portion of the first plastic encapsulation layer, a bottom surface of the first shielding layer, and a bottom surface of the second shielding layer.