M. Sc. (Physics Materials Science) (Semester IV) (CBCS)
Examination, 2017
MICROELECTRONICS
Day Date: Wednesday, 19-04-2017 Max. Marks: 70
Time: PM to 05.00 PM
N.B. Q.1 and Q2 are compulsory.
Attempt any Three from Q .No 3 to No.7
Use of non-programable calculator is allowed
All questions carry equal marks
Q.1 Choose the correct alternatives: 06
Crystalline Si has
Four valence electrons per atom
Two valence electrons per atom
Eight valence electrons per atom
No valence electrons
Oxidation process in Silicon planar technology is also called
as,
Photo Oxidation Vapour Oxidation
Silicon Oxidation Thermal Oxidation
The advantage of using Ion implantation process is
Due to lateral spreading is more
Beam current can be controlled
Its high temperature performance
Its performance at low temperature
The chemical reaction for the oxidation process
Si 2H2O SiO2 2H2
Si O2 SiO2
2Si+2H2O 2SiO2+2H2
2Si+2H2O+2O2 2SiO2+2H2+O2
Plasma etching is an example for,
Dry etching Wet etching
Both dry and wet etching None of the mentioned
In the context of IC fabrication, metallization means,
Connecting the metallic wires
Depositing SiO2 layer
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Forming interconnecting conduction and bonding pads
Covering with metallic cap
State whether true or false. 08
Miller indices are used to designate planes and directions
within a crystalline lattice.
During IC fabrication, Silicon wafers are usually cut along a
plane with a flat or notch to orient the wafer
In MOS capacitor, the preference in dielectric layer is given
to Silicon Nitride (Si3N4)
The value of collector series resistance of an integrated
transistor can be easily reduced by a process known as
"buried layer" or "Buried layer".
During ion implantation, the accelerated ions are passed
through Strong Electric field
The process of film deposition in cathode sputtering is very
much faster than evaporation method.
GaAs is easy to grow in crystal form compared to Si.
Metallization process takes place in vacuum evaporation
chamber, where the material is evaporated by focusing a
high power density electron beam.
Q.2. Write short notes on the following:
Clean room and safety requirements for the device fabrication 05
Masking characteristics 04
Die separation 05
Q.3 Discuss Dry chemical etching technique 06
With a neat sketch, explain the Molecular Beam Epitaxy process 08
Q.4 Discuss the Phosphorous diffusion technique in detail. 06
With a suitable example and relevant sketches, explain the
positive and negative photo resist patterning process
08
Q.5 Discuss electron beam lithography technique with a neat sketch 06
Discuss Chemical vapour deposition technique for the
deposition of silicon dioxide films
08
Q.6 Write a note on the multilevel metallization schemes 06
With a neat schematic, explain the DC sputtering technique 08
Q.7 Write a note on bonding and attachments 06
With relevant diagrams, explain the masking sequence and
process flow of n-MOS device