What Your Chemistry Teacher didn't tell You about Silicon


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Your high school chemistry teacher probably told you that the element silicon is used for making computer chips but have you ever wondered why that is the top choice of computer manufactures?  How exactly is this metalloid used and what part of the chip is actually made of silicon?  

250px-SiliconCroda.jpg

Silicon is a semiconductor that becomes more conductive as its temperature rises making it perfect for use in microchips.  It is also the second most abundant element on the earth, oxygen being the first,  and is found in many of our day to day surroundings.  The silicon used for microchips must be extremely pure.  The rule of thumb is "nine nines" meaning that the silicon must be 99.9999999% pure.  Silicon must be purified since the element very rarely occurs in its purest form naturally.  It can be purified by a few different methods but the most common is the Czochralski method which grows a pure silicon crystal that is then sliced into wafers to be used by microchip manufacturers.     

The pure silicon wafer is coated with a thin layer of silicon dioxide which is then etched away to reveal certain parts of the pure silicon beneath.  The etching process creates pathways that alter the conductivity at different sections on the chip.  Other elements are also used to dope the pure silicon to create the perfect amount of conductivity.  Oh, and doping in this context means to intentionally introduce impurities to semiconductors to make them act as conductors.


tiny-microchip.jpg

Each wafer that has been etched with individual pathways and components become a layer of the whole microchip.  Intel declared that as many as 30 layers can go into one chip!  Microchips are truly incredible works of modern technology and are becoming an increasing part of our everyday lives. 


Sources: http://www.intel.com/content/www/us/en/history/museum-making-silicon.html

http://www.computerworld.com/s/article/72461/Making_Microchips

http://www.southalabama.edu/engineering/ece/faculty/akhan/Courses/EE539-Fall04/Lecture-slides/lecture-4-crystal%20growth.pdf


Photo sources: http://www.pcb-sw.com/wp-content/uploads/path//tiny-microchip.jpg

http://en.wikipedia.org/wiki/File:SiliconCroda.jpg



1 Comment

This has zero to do with your post, but your picture with the lizard is too cute, hahaha.

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