This set of VLSI Multiple Choice Questions & Answers (MCQs) focuses on “CMOS Fabrication”.
1. CMOS technology is used in developing which of the following?
a) microprocessors
b) microcontrollers
c) digital logic circuits
d) all of the mentioned
View Answer
Explanation: CMOS technology is used in developing microcontrollers, microprocessors, digital logic circuits and other integrated circuits.
2. CMOS has __________
a) high noise margin
b) high packing density
c) high power dissipation
d) high complexity
View Answer
Explanation: Some of the properties of CMOS are that it has low power dissipation, high packing density and low noise margin.
3. In CMOS fabrication, nMOS and pMOS are integrated in same substrate.
a) true
b) false
View Answer
Explanation: In CMOS fabrication, nMOS and pMOS are integrated in the same chip substrate. n-type and p-type devices are formed in the same structure.
4. P-well is created on __________
a) p substrate
b) n substrate
c) p & n substrate
d) none of the mentioned
View Answer
Explanation: P-well is created on n substrate to accommodate n-type devices whereas p-type devices are formed in the ntype substrate.
5. Oxidation process is carried out using __________
a) hydrogen
b) low purity oxygen
c) sulphur
d) nitrogen
View Answer
Explanation: Oxidation process is carried out using high purity oxygen and hydrogen. Oxidation is a process of oxidizing or being oxidised.
6. Photoresist layer is formed using __________
a) high sensitive polymer
b) light sensitive polymer
c) polysilicon
d) silicon di oxide
View Answer
Explanation: Light sensitive polymer is used to form the photoresist layer. Photoresist is a light sensitive material used to form patterned coating on a surface.
7. In CMOS fabrication, the photoresist layer is exposed to __________
a) visible light
b) ultraviolet light
c) infra red light
d) fluorescent
View Answer
Explanation: The photoresist layer is exposed to ultraviolet light to mark the regions where diffusion is to take place.
8. Few parts of photoresist layer is removed by using __________
a) acidic solution
b) neutral solution
c) pure water
d) diluted water
View Answer
Explanation: Few parts of photoresist layer is removed by treating the wafer with basic or acidic solution. Acidic solutions are those which have pH less than 7 and basic solutions have greater than 7.
9. P-well doping concentration and depth will affect the __________
a) threshold voltage
b) Vss
c) Vdd
d) Vgs
View Answer
Explanation: Diffusion should be carried out very carefully, as doping concentration and depth will affect both threshold voltage and breakdown voltage.
10. Which type of CMOS circuits are good and better?
a) p well
b) n well
c) all of the mentioned
d) none of the mentioned
View Answer
Explanation: N-well CMOS circuits are better than p-well CMOS circuits because of lower substrate bias effect.
11. N-well is formed by __________
a) decomposition
b) diffusion
c) dispersion
d) filtering
View Answer
Explanation: N-well is formed by using ion implantation or diffusion. Ion implantation is a process by which ions of a material are accelerated in an electrical field and impacted into a solid. Diffusion is a process in which net movement of ions or molecules plays a major role.
12. _______ is sputtered on the whole wafer.
a) silicon
b) calcium
c) potassium
d) aluminium
View Answer
Explanation: Aluminium is sputtered on the whole wafer before removing the excess metal from the wafer.
Sanfoundry Global Education & Learning Series – VLSI.
To practice all areas of VLSI, here is complete set of 1000+ Multiple Choice Questions and Answers.
