1. Field of the Invention
The present invention relates to a semiconductor module mounting a plurality of circuit elements thereon.
2. Description of the Related Art
Portable electronic devices, such as mobile phones, PDAs, DVCs, and DSCs, are today gaining an increasing variety of functions. And to be accepted by the market, they have to be smaller in size and lighter in weight, and for that reason, there is a growing demand for highly-integrated system LSIs. On the other hand, these electronic devices are expected to be easier or handier to use, and therefore the LSIs used in those devices are required to be more functionally sophisticated and better performing. Thus the higher integration of LSI chips is causing increases in I/O count, which in turn generate demand for smaller packages. To satisfy both these requirements, it is strongly expected that semiconductor packages just right for the high board density packaging of semiconductor components be developed.
As a packaging technology to meet these demands for higher density, known are multi-chip modules (MCM) employing a multiple stack structure for the multilayering of circuit elements.
For example, a structure is known where two circuit elements with their electrode forming surfaces facing upward are stacked on a substrate and lower and upper circuit elements and wirings provided on the substrate are electrically wire-bonded, respectively.
In the conventional structure where the circuit elements and the wiring on the substrate side are connected through wire bonding, the height or thickness of a wire used in the wire bonding must be taken into consideration and assured. Accordingly, this becomes a restrictive factor in reducing the height and thickness of the semiconductor module, thus making it difficult to downsize and reduce the thickness of the semiconductor module.