Why PMOS is easier to fabricate than NMOS?

Thread Starter

wwchieh

Joined Apr 25, 2009
14
I am just curious to know why PMOS is easier to fabricate than NMOS when I read the history of the MOSFET. Thank you.
 

Wendy

Joined Mar 24, 2008
21,840
Actually you have it backwards, NMOS is by far the most common of the two, but both exist.

I'm having a little trouble backing up why this is, but Wikipedia offers a clue in its http://en.wikipedia.org/wiki/Power_MOSFET article, where it states the following...

The main disadvantage of this type of MOSFET is the poor on-state performance: it uses holes as charge carriers, which have a much lower mobility than electrons. As resistivity is directly related to mobility, a given PMOS will have a RDSon three times higher than a N-MOSFET with the same dimensions
Both are available, but the NMOS are a lot more easy to get, as looking for PMOS taught me. Basically NMOS are smaller than PMOS given the same specs.
 

nanovate

Joined May 7, 2007
665
Actually you have it backwards, NMOS is by far the most common of the two, but both exist.
In the old days the p-channel was more common. The process for it was developed first but as modern techniques were developed we were able to take advantage of the better physical properties of a n-channel device.
 
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