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A Look On How Lexar Memory Cards Are Made


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<p>Fascinating! I have seen this type of stuff being made before - the question that always comes into my mind is why is the original starting plate circular? Does anyone know why? I mean if you're going to make a bunch of square or rectangular chips, why start with a circle? Surely that is just a tad wasteful?</p>
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>>> I have seen this type of stuff being made before - the question that always comes into my mind is

why is the original starting plate circular? Does anyone know why? <P>

 

>>> Also circular shapes are easier to manage in the initial wafer production process. Try to have robots

fit or remove square or rectangular wafers into or from the various slots and machines.<P>

 

 

The very very short story... Not because of handling issues, but because single crystal silicon wafers (what you are calling

plates) are sliced off of what are called boules. Boules, are literally grown from from a seed crystal being

pulled in a highly controlled manner in high-temperature crucibles. Silicon boules grow naturally in the form

of cylindrical ingots in that growing process. Wafers are cut of the end of the ingots and then polished. The individual memory die, of which there are thousands on each sliced wafer,

are simply cut. Wafers today used for high-volume parts are 300mm in diameter, about 12 inches. About 20 years ago they were 3 inches; followed by 6 inches and 8 inches. Sometime in the future production wafers will be 450mm, about 18" inches in diameter. That's huge! The larger the wafer, the more good die (not all are good, there are defects) you end up with. There is a nice <a href= "http://en.wikipedia.org/wiki/Czochralski_process">diagram here.</a>

www.citysnaps.net
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