CMOS and N-TUB Fabrication Techniques

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Questions and Answers

What does the acronym CMOS stand for?

Compatible Metal Oxide Semiconductor

Controlled Metal Oxide Semiconductor

Complementary Metal Oxide Semiconductor (correct)

Compound Metal Oxide Semiconductor

What is the purpose of the SiO2 layer in CMOS fabrication?

To protect the substrate (correct)

To enhance electrical conductivity

To increase power consumption

To serve as a semiconductor base

Which of the following is NOT an advantage of CMOS over singular N and P MOSFETs?

Higher manufacturing costs (correct)

Compatibility with digital circuits

Greater noise immunity

Lower static power consumption

In the N-Tub fabrication process, what is applied to the wafer after it is doped with P-type impurities?

A photoresist film for lithography Signup and view all the answers

What chemical is used to remove the oxide layer during the CMOS fabrication process?

Hydrofluoric acid Signup and view all the answers

What happens during the masking step of the photolithography process?

A desired pattern of opaqueness is created. Signup and view all the answers

What is the final result of diffusing N-type impurities into the P-type substrate?

Formation of an N-well Signup and view all the answers

Why is CMOS considered better for modern technologies?

Less static power consumption Signup and view all the answers

What is the purpose of the oxidation layer during the deposition of polysilicon?

To serve as a protective shield during metallization processes Signup and view all the answers

In the context of NMOS fabrication, where are the NMOS transistors created?

In a p-well on an n-type substrate Signup and view all the answers

What is the role of metallic interconnections in the CMOS fabrication process?

To provide necessary electrical connections between terminals Signup and view all the answers

Which of the following statements correctly describes the p-type diffusion process?

It occurs on an n-type substrate for creating PMOS terminals Signup and view all the answers

During the deposition of polysilicon, what happens to the layers of polysilicon after gate formation?

The excess polysilicon is stripped off Signup and view all the answers

How does the doping concentration of the p-well affect NMOS devices?

It influences the voltage of n-type devices Signup and view all the answers

What is typically done to protect areas of the wafer where no terminals are required?

A thick field oxide layer is laid out Signup and view all the answers

What occurs after the excess metal is removed during CMOS fabrication?

Interconnections are formed for the terminals Signup and view all the answers

Study Notes

CMOS Fabrication

CMOS stands for Complementary Metal-Oxide Semiconductor.
CMOS uses both N and P-type MOSFETs.
CMOS has less static power consumption than single N or P-type MOSFETs.
CMOS is compatible with digital circuits because it combines N and P-type MOSFETs.
CMOS has better noise immunity than single N or P-type MOSFETs.
CMOS is used in various modern technologies: ICs, microprocessors, imaging sensors, RFICs, SoC integration.

N-TUB Fabrication

N-TUB fabrication starts with a p-type silicon wafer.
The wafer is oxidized to form a silicon dioxide layer.
Photolithography is used to create a pattern for selective etching.
Photoresist is applied and exposed to UV rays.
Unexposed photoresist is removed with a chemical developer.
Etching using hydrofluoric acid removes oxide in specific regions.
N-type impurities are diffused into the p-type substrate to create an N-well.
Polysilicon is deposited as the gate structure, using a CVD process.
A thin oxide layer is deposited over the polysilicon for the gate.
Masking and diffusion are used to form regions for the NMOS and PMOS transistors.
A thick field oxide layer is deposited as a protective layer.
Excess metal is removed, and terminals are formed for interconnections.

P-TUB Fabrication

P-TUB fabrication is another CMOS process.
The n-type substrate is used as the base.
A p-well is diffused into the substrate to accommodate the NMOS transistor.
The PMOS transistor is created on the n-type substrate.
The doping concentration and depth of the p-well affect the n-type devices' voltage.
Deeper wells require a larger surface area.

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Description

This quiz covers the fundamentals of CMOS and N-TUB fabrication processes, detailing key techniques used in the creation of integrated circuits. Explore the differences between CMOS technology and traditional N-TUB methods through a series of questions designed to test your understanding of semiconductor fabrication. Perfect for students studying electronics and materials science.