M.Sc. (Semester IV) (CBCS) Examination Nov/Dec-2018
(Materials Science)
MICROELECTRONICS
Time: 2½ Hours Max. Marks: 70
Instructions: Q 1 and Q 2 are compulsory.
Attempt any three questions from Q. 3 to 7.
All questions carry equal marks.
Use of Non programmable calculator is allowed.
Q.1 Choose correct alternatives. 14
The most complicated IC-technology today is
NMOS PMOS
CMOS I2L
In the project range distribution of impurity follows almost behavior.
Gaussian erfc
linear both b and c
Etch attacks are preferentially faster on a oriented silicon.


Novolac is Photoresist.
Negative Positive
Both a and b Neutral
Molecular beam epitaxy is low temperature process that
Minimizes out diffusion and auto doping
Increases out diffusion and auto doping
Minimizes out diffusion and increases auto doping
Increases out diffusion and decreases auto doping
In MBE evaporation of material that produces flux of atoms is
dependent.
Time Angle
Time and Angle Pressure
The reactor mainly used for plasma assisted deposition of Si O2 is
Hot wall plasma deposition
Radial flow parallel plate plasma assisted CVD
CVD
Hot wall reduced pressure
In instantaneous source diffusion surface concentration goes on
increasing decreasing
remains unaffected both a and b
Iso-polyphotoresist MR) is photoresist.
Positive Negative
Both a and b None
Page 2 of 2
SLR-VN-390
10) Emitters of transistors are fabricated by
constant source diffusion
instantaneous source diffusion
interstitial diffusion
self diffusion
11) of CMOS is one of its important attributes for high density
applications.
Low power consumption High power consumption
Fabrication process sequence Both b and c
12) Out of the following oxide charges, which are the orientations dependent?
Fixed oxide charges Interface trapped charges
Mobile ionic charges Oxide trapped charges
13) Glue layer in metallization is the reduction of SiO2 by
AI Ti
Mo Ta
14) For a schottky barrier between a metal and semiconductor with Φm and Φs as
the work functions, the band bending conditions occurs when
Φm Φs 0 Φm Φs
Φs Φm Φm Φs
Q.2 Attempt the following (any three) 14
Discuss: diffusion vs epitaxy
Why aluminum is chosen as metallization material?
Explain ion implantation.
What is redistribution during growth?
Q.3 Distinguish between substitutional diffusion and interstitial diffusion. Explain in
detail.
10
Mention the salient features of ion implantation. 04
Q.4 Discuss the evaluation of an epitaxy layer referred to:
Measurement of resistivity
Measurement of layer thickness
Doping profile
10
Write a note on thermal oxidation. 04
Q.5 Discuss how polysilicon is obtained using SiH4 08
What are the mass transport limited and surface reaction limited reactions? 06
Q.6 Show that the kinetics of Si-oxidation is parabolic and linear. 08
Write a note on orientation dependence of oxide growth rate. 06
Q.7 What is contact metallization? Discuss contact metallization referred to
contact resistance schottky barrier height and semiconductor doping
density
10
Why Aluminum is preferred as a metallization choice? 04