How difficult is it to create silicon chips and why?
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The difficulty depends on the “minimum feature size,” which is basically the size of individual transistors and wires on the chips. This differs among different chip types and their target markets. The most advanced chips, like PC CPUs and graphics processors, have transistor sizes of only a few nanometers, which demands the most expensive and difficult manufacturing in the world. Here are some of the challenges:
– Highly pure materials and [processing environment](https://en.m.wikipedia.org/wiki/Clean_room). The air in the facility must be filtered for tiny particles. Some areas are so clean that humans can’t enter; everything in those rooms is done with robotics. The temperature, humidity, and even lighting are tightly controlled.
– Chemical processes involving [ultra-pure chemicals and high-vacuum, cryonic environments](https://en.m.wikipedia.org/wiki/Molecular-beam_epitaxy). Other processes use very toxic, hazardous chemicals. And much of this work is slow, with sequences of repeated reactions, crystalization steps that take days, etc.
– Extremely precise robotic alignment and high-frequency laser lithography. The [key machine](https://en.m.wikipedia.org/wiki/Stepper) used to align a chip wafer for image projection costs about $150 million.
– Complex quality assurance. Defects are inevitable, and the company must recoup costs by determining which chips can still be sold with some disabled features
In addition to these technical difficulties, chip manufacturing has to overcome business challenges. The cost of building a modern fabrication facility ranges from three to nine *billion* dollars, and could rise to $20 billion within the next decade. In many countries, tax law – in particular the capital depreciation schedule – doesn’t account for the speed of evolution in the industry. This makes it expensive to idle the machines, so when next-gen technology arrives they must be quickly adapted for lower-end chip markets. Because of this, the industry doesn’t have much vertical integration. Instead, fabrication companies lease use of their facilities to chip design firms like Intel, AMD, Nvidia, etc. That allows for flexible arrangements that keep their machines continually busy.
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