Remember How to Build a Chip

Chip manufacturing illustrates some of the problems we encounter while building small. CMOS, pronounced sea moss, stands for complementary metal oxide semiconductors. Conceptually, making a chip is like designing and printing an etching we have designed on silicon. First conceive of and draw a pattern for the connectivity of the components. Then project this pattern as lines onto a wafer of crystallized silicon. Then with a caustic chemical etch away all the places we do not want silicon. Then deposit one layer of metal and semiconductor and then repeat the etching deposition process layer after layer until we build up an elaborate three-dimensional structure of trenches, columns and basins, each filled with metals and semiconductors. Each layer, however, retains its unique two-dimensional pattern confined within its own layer. To create three-dimensional mechanical parts from our 'sandwich,' we etch material away around our pieces until parts are thick enough to withstand the stresses and strains of working together as a MEMS. We can fashion from our cutouts, for example, diaphragms for micro-pumps and blood pressure sensors that flex when under pressure as well as cantilevers that work as accelerometers to activate airbags. But undoubtedly over time, all our 'pieces' will chafe because friction wears them away where they rub on each other.

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