Integrated Circuit (IC) Fabrication MCQ [Free PDF] – Objective Question Answer for IC Fabrication Quiz

61. Which semiconductor is most widely used for the fabrication of Integrated circuits?

A. Germanium, Ge
B. Gallium Arsenide, GaAs
C. Silicon, Si
D. All of the mentioned

Answer: C

Silicon is abundantly available in the form of sand. It is possible to form superior stable SiO2(Which has superb insulating properties). Whereas GaAs is more difficult to grow in crystal form and Ge crystal will be destroyed at high temperature.

 

62. What will be the next step after slicing (process) silicon wafers?

A. All of the mentioned
B. Lapping
C. Polishing
D. Chemical

Answer: A

When the silicon ingots are sliced for the given industrial dimension. It gives a rough surface and thus undergoes lapping, polishing, and chemical processing steps to get a smooth surface.

 

63. During the ion implantation process (before the ion strike the wafer) the accelerated ions are passed through

A. Strong Electric field
B. Strong Magnetic field
C. Strong Electric and Magnetic Field
D. None of the mentioned

Answer: B

During arc discharge in ion implantation, unwanted impurities get generated. The magnetic field acts to separate unwanted impurities from dopant ions.

 

64. In which method shallow penetration of dopants is possible?

A. Ion implantation
B. Vertical diffusion
C. Horizontal diffusion
D. Dopants diffusion

Answer: A

The depth of diffusion in this method can be easily regulated by control of the incident ion velocity and is capable of shallow penetration.

 

65. Which method is most suitable for silicon crystal growth in silicon wafer preparation?

A. Float zone process
B. Bridgeman-Stockbarger method
C. Czochralski crystal growth process
D. Laser heated pedestal growth

Answer: C

Czochralski crystal growth processes obtain a single crystal of semiconductor. The most important application of this method may be the growth of a large cylindrical ingot of single-crystal silicon.

 

66. Which is the most striking feature of a monolithic integrated circuit transistor?

A. Collector contact is present at the bottom of IC
B. Collector contact is present at the top of IC
C. Collector contact is absent
D. Collector contact is present on one of the sides of IC

Answer: B

In the IC transistor, the collector contact has to be taken from the top because the collector is isolated from the substrate and the next isolation island by reverse biased diodes.

 

67. Why monolithic IC transistor is preferred over discrete planar epitaxial transistor?

A. Due to the structural difference
B. Increase in VCE (sat) and collector series resistor
C. Improvement in circuit performance
D. All of the mentioned

Answer: D

As the collector contact is present on the top of the IC transistor, it makes a structural difference. Hence, it increases collector series resistance and VCE(sat) of the device. From this, circuit performance is highly improved as a matched transistor can be obtained.

 

68. Name the process that is used to overcome the increase in collector series resistance, which occurs due to the presence of collector contact at the top of the integrated transistor.

A. Buried n+ layer
B. Buried p+ layer
C. Triple diffused layer
D. Buried epitaxial layer

Answer: A

The value of collector series resistance of an integrated transistor can be easily reduced by a process known as the “buried layer” or “Buried n+ layer”.

 

69. What is the reason for using the Lateral PNP transistor in Integrated Circuits?

A. Requires simple process control
B. Simultaneous fabrication of PNP and NPN transistors
C. Provide good isolation
D. Miniaturization and cost reduction

Answer: B

During the p-type base diffusion for the NPN transistor, two adjacent p-regions are diffused to form the emitter and collector region of the lateral PNP transistor (the n-type epitaxial layer is used as the base of the PNP transistor). Thus, PNP and NPN transistors are fabricated simultaneously.

 

70. Which of the following transistor has the limitation, due to the requirement of additional fabrication steps and design consideration?

A. Vertical PNP transistor
B. Lateral PNP transistor
C. Triple diffused PNP transistor
D. Substrate PNP transistor

Answer: C

In the triple diffused PNP transistor fabrication process, an extra p-type diffusion is added to a standard NPN transistor after the n-diffusion to obtain a PNP transistor. However, the usefulness of such a structure is not used due to its limitation.

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