Interconnect substrate having cavity for stackable semiconductor assembly, manufacturing method thereof and vertically stacked semiconductor assembly using the same
An interconnect substrate includes vertical connection channels around a cavity. The vertical connection channels are made of a combination of metal posts and metallized vias. The cavity includes a recess in a core layer and an aperture in a stiffener. The metal posts, disposed over the top surface of the core layer, are sealed in the stiffener and are electrically connected to a buildup circuitry adjacent to the bottom surface of the core layer. The minimal height of the metal posts needed for the vertical connection can be reduced by the amount equal to the depth of the recess. The buildup circuitry is electrically connected to the metal posts through the metallized vias.
1. A method of making an interconnect substrate having cavity for stackable semiconductor assembly, the method comprising:
forming a protruded metal platform on a surface of a metal carrier;
forming a core layer covering the protruded metal platform and the remaining surface of the metal carrier, wherein the core layer has a first surface facing away from the metal carrier and an opposite second surface adjacent to the metal carrier;
forming an array of metal posts and a metal slug by removing a portion of the metal carrier, wherein the metal slug is aligned with the protruded metal platform;
forming a buildup circuitry from the first surface of the core layer, the buildup circuitry having an exterior surface facing away from the first surface of the core layer;
forming a stiffener that covers the second surface of the core layer and sidewalls of the metal slug and the metal posts, the stiffener having an exterior surface facing away from the second surface of the core layer; and
forming a cavity by removing the metal slug and a selected portion of the protruded metal platform and leaving a remaining portion of the protruded metal platform as a thermal paddle, the cavity including an aperture in the stiffener and a recess in the core layer and having sidewalls that extend from an exterior surface of the thermal paddle to the exterior surface of the stiffener;
wherein the metal posts are exposed from the exterior surface of the stiffener and electrically connected to the buildup circuitry through first metallized vias in the core layer, and the thermal paddle is thermally conductible to the buildup circuitry through second metallized vias in the core layer.
2. The method of claim 1 , further comprising a step of forming an array of auxiliary metal pads on the surface of the metal carrier before the step of forming the core layer, wherein the core layer also covers the auxiliary metal pads, and the metal posts are formed on the auxiliary metal pads.
3. The method of claim 2 , wherein the auxiliary metal pads have a thickness substantially equal to that of the protruded metal platform.