A multi-chip circuit module, having a plurality of semiconductor chips, such as ICs or LSIs, loaded thereon, is provided to electronic equipment adapted for handling digital signals, such as personal computers, portable telephone sets, video equipment or audio equipment. In this sort of the electronic equipment, attempts are made to reduce the size, weight and the thickness as well as to improve the performance and functions, diversify the functions and to expedite the processing, by reducing the size and improving the functions of the multi-chip circuit module by reducing the design rule of the circuit pattern and the size of the IC package, improving the degree of integration, increasing the number of package pins and by improving the mounting methods.
In certain types of the multi-chip circuit module, a so-called system LSI is formed by loading different functions, such as logic-memory functions or analog-digital functions. In certain types of the multi-chip circuit module, the functional blocks of the respective processes are manufactured by separate semiconductor chips which are then mounted on the same substrate to form a so-called multi-chip circuit module.
For further improving the performance in the multi-chip circuit module, the transmission speed and density of the signal lines across the microprocessor and memory chips prove a bottleneck, while the problem of delay caused in the signal lines needs to be tackled. In the multi-chip circuit module, even if the clock frequencies exceeding the GHz order is achieved within each device (chip), the clock frequencies need to be lowered by the order of magnitude of one digit because of such problems as signal delay or reflection. In the multi-chip circuit module, it is necessary to take measured against e.g., electromagnetic interference (EMI) or electromagnetic compatibility (EMC) by raising the transmission speed and density in the signal lines. Thus, in the multi-chip circuit module, it is necessary to improve the integration and performance not only as a chip technology but also as a system technology inclusive of the mounting technique of packages and boards. Among the conventional multi-chip circuit modules, there is such a one shown in FIG. 38. A multi-chip circuit module 100, shown in FIG. 38, is of the flip chip type in which plural semiconductor chips 102A, 102B are loaded on a major surface 101a of an interposer 101. In this multi-chip circuit module 100, suitable circuit patterns, lands or input/output terminals, not shown, are formed on front and back major surfaces 101a, 101b of the interposer 101. In the multi-chip circuit module 100, the semiconductor chips 102A, 102B are connected with a flip chip connection on predetermined lands 103 on the major surface 101a of the interposer 101, and the connection site is coated with an under-fill 104. In the multi-chip circuit module 100, solder balls 105 are loaded on the lands formed on the major surface 101b of the interposer 101. The multi-chip circuit module 100 may be mounted by reflow soldering to melt and solidiify the solder balls 105 by reflow soldering as the multi-chip circuit module 100 is set on for example a motherboard.
In the conventional multi-chip circuit module 100, the plural semiconductor chips 102A, 102B are mounted on the major surface 101a of the interposer 101 in the transversely arrayed state. In this case, the circuit pattern formed on the interposer 101 interferes with the wiring interconnecting the semiconductor chips 102A, 102B. In the multi-chip circuit module 100, an increasing number of semiconductor chips 102A, 102B are provided in keeping with the diversified functions and increasing speed of the device, so that an increasing number of the wirings are needed. In the multi-chip circuit module 100, the pitch of the wiring path formed in the interposer 101 manufactured by the routine substrate manufacturing technique is large and is of the order of approximately 100 μm in the least, due to e.g., constraints imposed by manufacturing conditions, such that the interposer 101 needs to be of a large area or of multiple layers in case of providing many interconnections across plural semiconductor chips 102A, 102B.
If, in the multi-chip circuit module 100, the multi-layered interposer 101 is used, inter-layer connections or connections across the semiconductor chips 102A, 102B are made through vias. From the working conditions, the via diameter is approximately 50 μm in the least, while the land diameter is approximately 50 μm in the least, so that the interposer 101 needs to be of a large size. In the multi-chip circuit module 100, the wiring path on the interposer 101 interconnecting the semiconductor chips 102A, 102B is elongated, such that L-C-R components are increased.
In the multi-chip circuit module 100, plural semiconductor chips 102A, 102B are mounted on one major surface of the interposer 101, while the other major surface thereof are provided with numerous connection bumps so as to be used as a mounting surface for mounting on a motherboard. Thus, the multi-chip circuit module 100 is implemented as a single surface mounting type module not provided on its mounting surface with the semiconductor chips 102A, 102B or other electronic components to render it difficult to take in the peripheral circuit of the semiconductor chips 102A, 102B or to achieve a high density mounting.