Package structure and method of fabricating the same

A package structure, comprising:

• a first semiconductor die comprising a first semiconductor substrate, first conductive pads disposed on the first semiconductor substrate, first conductive posts disposed on the first conductive pads, a first alignment mark located on the first semiconductor substrate, the first alignment mark comprises first stripe patterns, and a protection layer in physical contact with and covering the first conductive posts and the first alignment mark, wherein a top surface of the first conductive posts is leveled with a top surface of the protection layer;
• a second semiconductor die comprising a second semiconductor substrate, second conductive pads disposed on the second semiconductor substrate, second conductive posts disposed on the second conductive pads, and a second alignment mark located on the second semiconductor substrate, the second alignment mark of the second semiconductor die comprises second stripe patterns;
• an insulating encapsulant encapsulating the first semiconductor die and the second semiconductor die, wherein the insulating encapsulant is in physical contact with the second conductive posts and the second alignment mark of the second semiconductor die, and is physically separated from the first conductive posts and the first alignment mark of the first semiconductor die by the protection layer;
• a redistribution layer disposed on a top surface the insulating encapsulant and electrically connected to the first semiconductor die and the second semiconductor die;
• and
• a backside redistribution layer disposed on a bottom surface of the insulating encapsulant, wherein the first conductive posts, the first conductive pads and the first alignment mark of the first semiconductor die, the second conductive posts, the second conductive pads and the second alignment mark of the second semiconductor die, and the insulating encapsulant are located in between inner surfaces of the redistribution layer and the backside redistribution layer.

A method of fabricating a package structure, comprising:

• providing a first semiconductor substrate having first conductive pads thereon;
• forming a first passivation layer with first openings revealing the first conductive pads;
• forming first conductive posts within the first openings and over the first conductive pads;
• forming a first alignment mark located on the first passivation layer;
• forming a protection layer in physical contact with and covering the first conductive posts and the first alignment mark;
• performing dicing to obtain first semiconductor dies;
• providing a second semiconductor die, wherein the second semiconductor die has a second semiconductor substrate having second conductive pads thereon, a second passivation layer covering the second conductive pads and having a second opening exposing the second conductive pads, second conductive posts disposed on the second conductive pads within the second opening, and a bulk alignment mark located on the second passivation layer;
• and
• forming a second alignment mark on the second passivation layer, wherein the bulk alignment mark is etched to form an undercut during forming the second alignment mark;
• placing the first semiconductor die onto a backside redistribution layer over a carrier and performing a first alignment process using the first alignment mark for alignment;
• placing the second semiconductor die beside the first semiconductor die and performing a second alignment process using the second alignment mark for alignment;
• forming an insulating material over the carrier covering the first semiconductor die and the second semiconductor die, wherein the backside redistribution layer is disposed on a bottom surface of the insulating material;
• performing a planarization step on the insulating material to form an insulating encapsulant encapsulating the first semiconductor die and the second semiconductor die, wherein after the planarization step, a top surface of the first conductive posts is leveled with a top surface of the protection layer, and wherein the insulating encapsulant is in physical contact with the second conductive posts and the second alignment mark of the second semiconductor die, and is physically separated from the first conductive posts and the first alignment mark of the first semiconductor die by the protection layer;
• and
• forming a redistribution layer on a top surface of the insulating encapsulant, wherein the redistribution layer is electrically connected to the first semiconductor die and the second semiconductor die, and wherein the first conductive posts, the first conductive pads and the first alignment mark of the first semiconductor die, the second conductive posts, the second conductive pads and the second alignment mark of the second semiconductor die, and the insulating encapsulant are located in between inner surfaces of the redistribution layer and the backside redistribution layer.