N-Well, P-Well, and Twin-Tub CMOS Processes N-well CMOS: An N-well is a fabrication region with a p-type semiconductor. It is created by adding a hea...
N-well CMOS:
An N-well is a fabrication region with a p-type semiconductor.
It is created by adding a heavily doped region called a p-well near the drain region.
This region is reversed biased, which acts as a source of additional electrons.
When a voltage is applied to the N-well, the electrons from the p-well flow into the N-well region, forming a complete circuit between the source and drain.
This is the basic structure of a bipolar junction transistor (BJT), with the N-well representing the emitter and the drain representing the collector.
P-well CMOS:
A P-well is a fabrication region with an n-type semiconductor.
It is created by adding a heavily doped region called an n-well near the source region.
This region is forward biased, which acts as a sink of holes.
When a voltage is applied to the P-well, the holes from the n-well flow into the P-well region, forming a complete circuit between the source and drain.
This is the basic structure of a bipolar junction transistor (BJT), with the P-well representing the emitter and the source representing the collector.
Twin-tub CMOS:
A twin-tub CMOS is a combination of two separate N-well or P-well structures connected in a complementary fashion.
One N-well is connected to the source, and the other is connected to the drain.
Both wells are connected to the same collector.
This structure allows for the fabrication of a single transistor with multiple terminals, making it suitable for specific applications.
These three types of CMOS processes are used in the fabrication of transistors, which are essential building blocks of digital circuits. Each process has its unique characteristics and is used to achieve specific device functionalities and performance characteristics