Patent ID: 9455211
Filing Date: 2016-09-27
CPC Classification: H01L

Claim Text:
1. A structure comprising: a first package comprising: a molding compound; a through-via penetrating through the molding compound; a device die molded in the molding compound; and a buffer layer on and contacting the molding compound, an opening being through the buffer layer to the through-via, the buffer layer having ripples in a plane parallel to an interface between the molding compound and the buffer layer and around a circumference of the opening, wherein a peak and a valley of the ripples are both disposed in the plane parallel to the interface between the molding compound and the buffer layer, and a guiding trench, wherein the guiding trench forms a ring, and wherein the guiding trench completely encircles a center portion of the buffer layer in a top-down view of the structure, with the center portion of the buffer layer overlapping an entirety of the device die.