Ken wrote:
> 
> Dan Connelly wrote:
> 
> > The problem reminds me of the one in semiconductor device processing,
> > where Monte-Carlo is being used to predict the distribution of ions
> > which result from the bombardment of semiconductor device surfaces
> > with charged dopants.  Some excellent results were demonstrated
> > at the latest International Electron Device Conference in San Francisco
> > of the use of some clever but relatively simple techniques to get
> > more out of each randomly sampled ion event.  For example, one can
> > do "particle splitting" in which more than one particle shares part of a path,
> > but then part way through is split into multiple particles to generate
> > different random paths.  But I digress....
> 
> I regress ...
> 
> What is the benefit of the above process. It sounds like
> they are trying to increase electron flow while reducing
> resistance at the junction. Mosfet applications ?


Which process?  The physical process?  If so, yes -- the primary application
is the formation of MOSFETs.  For example, As+ implanted into B-doped Si
results in "islands" of electron-rich (electrons coming from the As, which has
valence of 5, and thus has an extra electron to give to the lattice) Si connected
with electron-deficient regions (the B has valence of 3, and thus traps electrons).
An electrode above an insulating plate connecting the electron-rich regions
is used to control a sheet of electrons at the surface which, if formed,
closes the switch.  If not, the electron-rich islands are isolated, and
the switch is "open".
 
The simulation process is used to predict the extent of the electron-rich
islands -- the goal is to keep them as dense and compact as possible... this
allows them to be placed in close proximity (separated by approximately 
0.1 micrometers in cutting-edge technology), increasing the speed at which
the connection can be switched.

Dan

P.S. There are also devices with electron-deficient islands formed in an
electron-rich region.... in this case the conduction is via "holes" rather
than "electrons".  Both devices are used in conjunction to form "CMOS".

-- 
http://www.flash.net/~djconnel/

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