The electrical and thermal study of membrane multi-chip module systems

A membrane multi-chip module (MCM) technology was developed to address future MCM interconnection requirements. This MCM achieved a high density of low-parasitic contacts by utilizing conventional IC processing technology. A membrane MCM is made by attaching chips to a membrane which is made of polyimide on a silicon substrate. The chip-to-chip interconnections consist of conducting wires that run on the MCM substrate and the membrane. Multiple levels of wires can be fabricated to increase the flexibility of routing. Continuity of chains with 400 contacts has been confirmed. Contact resistance measurements showed uniformity over the entire chip. For the module substrate with only one layer of metal, the contact resistance was 0.060 and 0.024;Membrane MCMs have been fabricated to investigate the electrical performance of advanced MCM systems. Custom bipolar interface circuits have been explored to interconnect CMOS chips, achieving a chip-to-chip delay of 5.6 nsec. The signal delay of the circuits was measured to study the influence of interconnection capacitance. Membrane MCM benefits signal propagation because the interconnection capacitance of the MCM substrate is much smaller than that on chip. Integrated decoupling capacitors and bipolar transistors were utilized to reduce simultaneous switching noise. With both provisions, the peak-to-peak noise has been reduced by a factor of about 3.2.;The thermal management of the membrane multi-chip technology is simple because both the silicon substrate and the attached chips can be placed on a heat sink so that the heat can be conducted away efficiently. The use of water buffer as a thermal capacitor to absorb excess heat and prevent sudden surges of chip temperature in the switching system which is explored. The time constant of the thermal system was increased from 0.6 to 1 sec, with the water buffer. The water also provided an additional heat removal path to the heat sink, reducing the thermal resistance from 25 to 17...