Package configuration and manufacturing method enabling the addition of decoupling capacitors to standard package designs
View Patent ↗The present invention is directed to a method of fabricating an integrated circuit package having decoupling capacitors using a package design conceived for use without decoupling capacitors. The package is implemented with a minimal redesign of the original design and not requiring any redesign of the signal trace pattern. The invention involves replacing top and bottom bond pads with via straps and then covering the top and bottom reference planes with a dielectric layer having conductive vias that electrically connect with the underlying via straps. Planes having the opposite polarity of the underlying reference plane are then formed on the dielectric layer. These planes include an array of bonding pads in registry with the vias. Decoupling capacitors are mounted to the top of the package and electrically connected with the plane on top of the package and the immediately underlying reference plane without the electrical connections to the capacitors passing through the signal planes of the package.
1. A method of forming an integrated circuit package with a decoupling capacitor using a package design configured for use without decoupling capacitor, the method comprising:
providing an initial design for an integrated circuit package substrate wherein the design is configured in a first circuit arrangement having an array of top mounted bond pads and a first circuit pattern arranged in a first stripline configuration, the initial design originally designed to construct the package substrate so that that does not have decoupling capacitors;
providing a supplementary design for adding a capacitive element to the integrated circuit package substrate wherein the supplementary design is a modification of the initial design such that the addition of the capacitive element does not alter the first circuit pattern of the first stripline configuration and further incorporates a first dielectric layer, a supplemental plane, and at least one capacitive element into the second design;
forming a multi-layer package substrate in accordance with the initial design and the second design, wherein the forming comprises;
forming a base substrate formed generally in accordance with the initial design so that the base substrate is arranged in the first stripline configuration comprising a signal plane stacked between a pair of parallel reference planes, and further comprising an upper package surface having a first plane formed thereon, the first plane comprising one of the reference planes and an array of via straps that are electrically connected with the internal signal plane such that the array of via straps are arranged in place of the array of bond pads of the initial design;
forming a first dielectric layer over the upper package surface wherein the first dielectric layer includes an array of conductive vias formed in registry with the array of via straps of the upper package surface;
forming the supplemental plane on a top surface of the first dielectric layer, the supplemental plane having a polarity opposite of the first plane, the supplemental plane further including an array of top bond pads arranged in registry with the array of vias; and
forming at least one decoupling capacitive element such that the capacitive element is electrically connected with the first plane and the supplemental plane.
2. The method of claim 1 wherein forming the at least one decoupling capacitive element comprises mounting a decoupling capacitor on the top surface of the first dielectric layer such that the capacitor is electrically connected with the first plane and the supplemental plane.
3. The method of claim 1 wherein forming the first dielectric layer over the upper package surface comprises forming the first dielectric layer with a layer of high-K dielectric material; and
wherein forming the at least one decoupling capacitive element comprises electrically connecting with the high-K dielectric layer so that the layer of high-K dielectric material operates as a decoupling capacitive element that is electrically connected with the first plane and the supplemental plane.