Hybrid microelectronic substrate and methods for fabricating the same

A hybrid microelectronic substrate, comprising:

• a high density microelectronic patch substrate having a first surface, an opposing second surface, and at least one side, wherein the high density microelectronic patch substrate comprises a plurality of dielectric layers and a plurality of conductive routes, wherein the plurality of conductive routes comprise a plurality of conductive traces in or on each dielectric material layer of the plurality of dielectric layers, and wherein the conductive traces are connected with a plurality of conductive vias extending through each dielectric layer of the plurality of dielectric layers;
• and
• a lower density microelectronic substrate, wherein the high density patch substrate is embedded within a first dielectric layer of the lower density microelectronic substrate, wherein a first dielectric material layer of the lower density microelectronic substrate contacts at least one dielectric layer of the plurality dielectric layers of high density microelectronic patch substrate at the second surface thereof and contacts the at least one side of the high density microelectronic patch substrate, wherein the lower density microelectronic substrate includes at least one additional dielectric material layer on the first dielectric material layer, wherein at least one conductive route of a plurality of conductive routes within the lower density microelectronic substrate is in electrical contact with at least one conductive route of the plurality of conductive routes within the high density microelectronic patch substrate at the high density microelectronic patch substrate second surface through a conductive blind via extending through and contacting the additional dielectric material layers and a portion of first dielectric material layer, wherein the at least one conductive blind via comprises a single via and a conformal layer of conductive material in the via, and wherein the at least one conductive blind via electrically contacts at least one conductive route of a plurality of conductive routes within the lower density microelectronic substrate and contacts at least one conductive route of a plurality conductive routes within the high density microelectronic patch substrate.