Editing MOSFET (section)

=== Junction design ===
The source-to-body and drain-to-body [[p-n junction|junctions]] are the object of much attention because of three major factors: their design affects the [[Current-voltage characteristic|current-voltage (''I-V'') characteristics]] of the device, lowering output resistance, and also the speed of the device through the loading effect of the junction [[capacitance]]s, and finally, the component of stand-by power dissipation due to junction leakage.
[[file:MOSFET junction structure.png|thumb|upright=1.2|MOSFET showing shallow junction extensions, raised source and drain and halo implant. Raised source and drain are separated from gate by oxide spacers.]]
The drain induced barrier lowering of the threshold voltage and [[channel length modulation]] effects upon ''I-V'' curves are reduced by using shallow junction extensions. In addition, ''halo'' doping can be used, that is, the addition of very thin heavily doped regions of the same doping type as the body tight against the junction walls to limit the extent of [[depletion region]]s.<ref name=Colinge>{{ cite book | first1 = Jean-Pierre|last1=Colinge |first2=Cynthia A.|last2=Colinge | title=Physics of Semiconductor Devices | year = 2002 | page = 233, Figure 7.46 | publisher = Springer | location = Dordrecht | isbn = 978-1-4020-7018-1 | url = https://books.google.com/books?id=ZcDE-ENKh2gC&pg=PA233}}</ref>

The capacitive effects are limited by using raised source and drain geometries that make most of the contact area border thick dielectric instead of silicon.<ref name=Weber>{{ cite book | editor1-first= Eicke R.|editor1-last=Weber|editor2-first=Jarek|editor2-last=Dabrowski| title = Predictive Simulation of Semiconductor Processing: Status and Challenges | year = 2004 | page = 5, Figure 1.2 | publisher = Springer | location = Dordrecht | isbn = 978-3-540-20481-7 | url = https://books.google.com/books?id=oCH9tiY7VeoC&pg=PA5}}</ref>

These various features of junction design are shown (with [[artistic license]]) in the figure.