🚀 go-pugleaf

In article <1993Jan6.142124.25566@bmers95.bnr.ca> khor@bnr.ca writes:
>                                 
>There's a question I'd always wanted to ask.  Why are wafers still made circular?
>Since the dice are rectangular, wouldn't it save material growing the crystals
>in a rectangular wafer?  
>
	The method for growing Si wafers is called the Czochralski process,
commonly abbreviated as the CZ (pronounced see-zee) process.  In this       
technique, a small seed crystal of a certain orientation is placed at the 
end of a mechanism that dips it into a melt of Si and the appropriate dopants
and slowly raises it while turning it all the time.  This produces a long 
cylindrical ingot of Si, which is then sliced into thin wafers, polished
and sent to the epitaxial process.  Here, a thin epitaxial layer, typically
just a few microns thick is grown on the wafer by vapor phase epitaxy.
	This is the start material for a wafer production line.  I would 
recommend the book "VLSI Technology" by Simon Sze.  It explains the various
steps in chip production, like epitaxy, diffusion, lithography, etch and
thin film deposition very well, and is eminently readable.


-- 
Sam Sivakumar		    |  Intel's very own lithography dude, 
ssivakum@ptdcs5.intel.com   |  Speakin' for himself, that's for sure!
PTD, Aloha, OR              |