Method of making a multichip module substrate

Abstract

A multichip module substrate for use in a three-dimensional multichip module, and methods of making the same, are disclosed. The substrate comprises a thin film structure, for routing signals to and from integrated circuit chips, formed over a rigid support base. Apertures are formed in the support base exposing the underside of the thin film structure, thereby allowing high density connectors to be mounted on both surfaces of the thin film structure, greatly enhancing the ability to communicate signals between adjacent substrates in the chip module. This avoids the need to route the signals either through the rigid support base or to the edges of the thin film structure. Power and ground, which do not require a high connection density, are routed in low impedance paths through the support base. Preferably, the thin film structure is made of alternating layers of patterned metal, such as copper, and a low dielectric organic polymer, such as a polyimide.