Copper interconnect

Every chip has a base layer of transistors, with layers of transistors, with layers of wiring stacked above to connect the transistors to each other and, to the rest of the computer. The transistors at the first level of chip are a complex construction of silicon, metal, and impurities precisely located to create the millions of minuscule on-or-off switches that make up the brains of a microprocessor. Breakthroughs in chip technology have most often been advances in transistor-making. As scientists kept making smaller, faster transistors and packing them closer together, the interconnect started to present problems.

Aluminum has long been the conductor of choice, but it reached the technological and physical limits of existing technology. Pushing electrons through smaller and smaller conduits becomes harder to do aluminum just isn't fast enough at these new, smaller sizes. Scientists had seen this problem coming for years and sought to find a way to replace aluminum with one of the three metals that conduct electricity better: copper silver or gold. However, afer many years of trying on one had succeeded in making a marketable copper chip.

All this changed in September 1998, when IBM used its revolutionary new copper interconnect technology to product a chip which used copper wires, rather than the traditional aluminum interconnects, to link transistors. This seemingly minor change is likely to have significant repercussions for future processor designs. Copper interconnects promise the ability to shrink die sizes and reduce power consumption, while allowing faster CPU speeds from the basic design. 38