DivyaSep
DivyaSep
Branch Unspecified
29 Jul 2015

A doubt in MOSFET/ CMOS fabrication

Inmos


cmos
I found these two diagrams Now my doubt is that in the first NMOS diagram the p-substrate is directly taken as base but in the second CMOS diagram p+ is taken as base what might be the reason for that?
Jeffrey Arulraj

Jeffrey Arulraj

Electronics and Communication
29 Jul 2015
If you have seen any package of MOSFET you will note that there are 4 lets from them and even your academics will tell there is a pin called substrate.

In the second image we have P layer as a substrate and the P+ serves as the Body of the MOS and the p layer has insufficient dopant concentration to provide charge carriers to enable conduction in the Transistor

Where as in the case of a individual NMOS there is no need for two P layers as you know that the amount of carriers got is more than enough to turn the device on

Feel free to ask any question related to this.
DivyaSep

DivyaSep

Branch Unspecified
30 Jul 2015
Jeffrey Samuel
If you have seen any package of MOSFET you will note that there are 4 lets from them and even your academics will tell there is a pin called substrate.

In the second image we have P layer as a substrate and the P+ serves as the Body of the MOS and the p layer has insufficient dopant concentration to provide charge carriers to enable conduction in the Transistor

Where as in the case of a individual NMOS there is no need for two P layers as you know that the amount of carriers got is more than enough to turn the device on

Feel free to ask any question related to this.

Thank you so much

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