The source and drain doping profiles are modeled using Gaussian functions
which will be described in Section 3.1.5. They are shown in
Fig. 3.3 for Device Generation A and Device Generation B. The
maximum impurity concentration at the surface is 10 cm
.
The
exact values of the junction depths depend on the substrate background doping.
Rough values are 50-120 nm for the 0.25
m device and 20-48 nm for the
0.1
m device.
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The shallow source/drain implants of Fig. 3.3 are usually called ``source/drain extensions'' or just ``tips''. Additional deep source/drain implants normally used to reduce the series resistance and to provide a good interface to the contacts are not taken into consideration in this work since a proper design of deep source/drain implants implies that they do not significantly affect what happens in the channel region of a MOS transistor.