Various aspects of the present disclosure set forth IC dies, microelectronic assemblies, as well as related devices and packages, related to direct chip attach of dies and circuit boards. An example microelectronic assembly includes a die with IC components provided over the die's frontside, and a metallization stack provided over the die's backside. The die further includes die interconnects extending between the frontside and the backside of the die, to electrically couple the IC components and the metallization stack. The assembly further includes backside conductive contacts, provided over the side of the metallization stack facing away from the die, the backside conductive contacts configured to route signals to/from the IC components via the metallization stack and the die interconnects, and configured to be coupled to respective conductive contacts of a circuit board in absence of a package substrate between the die and the circuit board.

A circuit board includes a semiconductor substrate having a first surface and a second surface located on an opposite side from the first surface, a through hole penetrating the first surface and the second surface, an organic insulating film disposed on the first surface and a side surface of the through hole, and a conductor disposed on an opposite side of the organic insulating film from a side surface side of the through hole. The side surface of the through hole has a first side surface coupled to the first surface and having a width decreased from the first surface toward the second surface, and a second side surface coupled to the second surface from an end portion of the first side surface on a second surface side.