INTEGRATED CIRCUIT (IC) PACKAGE SUBSTRATE WITH EMBEDDED TRACE SUBSTRATE (ETS) LAYER ON A SUBSTRATE, AND RELATED FABRICATION METHODS

Integrated circuit (IC) package substrate with an embedded trace substrate (ETS) layer on a substrate, and related fabrication methods. The package substrate of the IC package includes an ETS layer provided on the substrate to facilitate providing higher density substrate interconnects to provide bump/solder joints for coupling a semiconductor die to the package substrate. ETS interconnects in the ETS layer in the package substrate facilitates die connections having a reduced line-spacing ratio (L/S) (e.g., 5.0 micrometers (μm)/5.0 μm or less) over substrate interconnects in a substrate. In additional exemplary aspects, raised metal pillar interconnects are formed in contact with respective ETS interconnects of the ETS layer of the package substrate to avoid or reduce metal consumption by die solder disposed on metal pillar interconnects of the ETS layer providing bump/solder joints.