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HIGH-TEMPERATURE ELECTRONIC DESIGN

Part 1: What Are Your Options?
by George Novacek

Start ı A Little Theory ı Size and Type ı Silicon Bipolar Transistors ı Silicon MOSFETs ı Six of Oneı ı SOI Technology ı Other Operation Problems ı Sources and PDF

OTHER OPERATION PROBLEMS

Bringing the electrical characteristics of semiconductors, particularly leakage, under control is only a partial solution to the problem. Metal electromigration, metallization, and corrosion become critical concerns and, if not properly addressed, result in drastic reduction of reliability. Electromigration and corrosion are the major factors limiting the life of conductors and electrical contacts operating at elevated temperatures.

Packaging integrity is another serious concern, as the present day packaging plastics begin to disintegrate after the temperature exceeds about 200ıC. To date, metal encapsulation remains the only viable alternative for high-temperature devices.

Of paramount importance is the resistivity of the internal IC connections, because it directly affects the speed, power loss, and local heating effects. It is important to note that only the third and fourth lowest resistivity metals (gold, Au ı2.35 x 10^ı8 ohm/m and aluminum, Al ı2.653 x 10^ı8 ohm/m) have been used as thin films in large-scale integrated circuits manufacturing. Copper (Cu), with its resistivity of 1.63 x 10^ı8 ohm/m, rates in second place, having the benefit of 42% improvement over the conductivity of aluminum. Copper is difficult to use in silicon fabrication, but great strides have already been made in using it in silicon-based ICs. Intelıs Coppermine series is a good example, but aluminum and gold still hold the lead. The highest conductivity metal (silver, Ag, with 1.59 x 10^ı8 ohm/m) seems to be too difficult to match with the current silicon IC fabrication process.

Iıve discussed quite a bit in this first part, and because Iıve already covered internal IC connections, next month Iıll go into soldering, wire insulation, and so forth. They are concerns for successful high-temperature operation. Iıd also like to take a look at passive components. So, join me next month, and Iıll pick up where I left off.

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