Die assembly on thin dielectric sheet

A method comprising:

• attaching a first and a second die to a carrier, the first and the second die each having interconnect areas on a side opposite the carrier;
• attaching a dielectric sheet over the interconnect areas of the first and the second die, the dielectric sheet having a polished surface facing the dies, and being stable to 600° C.;
• forming conductive vias in the dielectric sheet over the interconnect areas after attaching the dielectric sheet to connect with pads of the interconnect areas;
• depositing build-up layers over the dielectric sheet, the build-up layers including routing to connect pads of the first die interconnect area to pads of the second die interconnect area through the conductive vias;
• and
• packaging the dies, the dielectric sheet, and the build-up layers by mounting the dies to a package substrate through the build-up layers.