51. Which component is not used as an impurity in the diffusion process?
A. Phosphorous
B. Boron chloride
C. Phosphorous pentaoxide
D. Boron oxide
Answer: A
Phosphorous is not used as an impurity in the diffusion process.
The elemental form of Phosphorous is not added directly as an impurity in the diffusion process.
52. In the ion implantation method, penetrating the ions into the silicon wafer depends upon
A. Accelerating voltage
B. Accelerating speed
C. Accelerating current
D. All of the mentioned
Answer: A
In the ion implantation method, penetrating the ions into the silicon wafer depends upon accelerating voltage.
The depth of penetration of any particular type of ion increases with increasing accelerating voltage.
53. What is the advantage of using the Ion implantation process?
A. Lateral spreading is more
B. Performed at high temperature
C. Beam current-controlled from outside
D. Performed at low temperature
Answer: C
In the diffusion process, the temperature has to be controlled over a large area inside the oven, whereas in the ion implantation technique, accelerating potential and the beam current are electrically controlled from the outside.
54. The major disadvantage of the PN-junction isolation technique is:
A. Formation of Parasitic Resistance
B. Formation of Parasitic Capacitance
C. Formation of Isolation island
D. None of the mentioned
Answer: B
The presence of Parasitic Capacitance at the isolating PN-junction results in an inevitable capacitor coupling between the component and substrate. This also limits the performance of circuits at high frequencies.
55. Which isolation technique is used in applications like military and aeroscope?
A. Thin-film isolation
B. PN-junction isolation
C. Barrier isolation
D. Dielectric isolation
Answer: D
In dielectric isolation, a layer of solid dielectric is used for isolation purposes. This layer is thick enough such that its associated capacitance is negligible. Moreover, it is more expensive, which is justified by its superior performance.
56. Aluminium is usually used for the metallization of most IC as it offers
A. Relatively a good conductor
B. High resistance
C. Good mechanical bond with silicon
D. Deposition of aluminum film using vacuum deposition
Answer: C
Aluminum is usually used for the metallization of most IC as it offers a good mechanical bond with silicon.
Aluminum forms low resistance (it is a good conductor of electricity). Therefore, it forms ohmic contact (Semiconductor-metal contact) with p-type silicon and heavily doped n-type silicon.
57. How the aluminum film coating is carried out in the metallization process?
A. Heating and pouring aluminum in the required place.
B. Aluminium is vacuum evaporated and then condensed
C. Placing the aluminum in the required place and then heating it using tungsten
D. None of the mentioned
Answer: B
The metallization process takes place in the Vacuum evaporation chamber, where the material is evaporated by focussing a high power density electron beam. Vapors then hit the substrate and get condensed to form a thin-film coating.
58. What type of packing is suitable for Integrated Circuits?
A. Metal can package
B. Dual-in-line package
C. Ceramic flat package
D. All of the mentioned
Answer: D
These packages are the three different possible packages available in Integrated Circuits. Its usage depends upon the number of leads required for application.
59. Metal can IC packages are available in
A. 42 leads
B. 16 leads
C. 12 leads
D. 24 leads
Answer: C
The maximum lead available in a metal can IC package is 12. The remaining lead numbers are commonly available in dual-in-line packages.
60. What process is used in the semiconductor industry to fabricate Integrated Circuits?
A. Silicon wafer preparation
B. Silicon planar process
C. Epitaxial growth of silicon
D. Photolithography process
Answer: B
The planar process (Silicon planar technology) in the semiconductor industry built individual components. It is the primary process by which Integrated Circuits are built. The other processes are the different steps involved within the planar process.
