M.Sc. (Semester IV) (CBCS) Examination Oct/Nov-2017
Material Science
MICROELECTRONICS
Day Date: Friday, 17-11-2017 Max. Marks: 70
Time: 02.30 PM to 05.00 PM
Instructions: and are compulsory.
Answer any three questions from Q.3 to Q.7.
All questions carry equal marks.
Q.1 Choose the correct alternative:- 06
The most suitable method for the silicon crystal growth in silicon
wafer preparation?
Float zone process Czochralski crystal growth
process
Birdgeman-Stockbarger
method
Laser heated pedestal
growth
To obtain crystal structure while fabricating the integrating circuits the
commonly used method is,
Oxidation Photolithography
Epitaxial growth Silicon wafer preparations
Oxidation process is required because
To protect against contamination
To prevent diffusion impurities
To use it for fabrication various components
All of the mentioned
Th chemical reaction for the oxidation process
Si 2H2O →SiO2 2H2
2Si 2H2O →SiO2 2H2
Si O2 →SiO2
2Si 2H2O 2O2 → 2SiO2 2H2 O2
The process involved in photolithography is
Making of a photographic mask only
Photo etching
Both photo etching and making of a photographic mask
None of the mentioned
In ion implantation method, penetrating the ions into the silicon wafer
depends upon
Accelerating voltage Accelerating current
Accelerating speed All of the mentioned
SLR-MO-539
State True or False/ Fill in the blanks: 08
The aluminium film coating is carried out in metallization process is
initially by vacuum evaporation and then condensation
SiO2 used as metallic film in the thin film resistor.
In MOS capacitor, the preference in dielectric layer is given to Silicon
Nitride(Si3N4)
Plasma etching is preferred to make the photoresist immune to
etchants.
During ion implantation, the accelerated ions are passed through
Strong Magnetic Field.
Boron is a n-type material, whereas phosphorus is an p-type material
Aluminium is usually used for metallization of most IC as it offers
good mechanical bond with silicon.
In cathode sputtering high energy particle diffuse through low
pressure gas and deposits on the substrate.
Q.2 Write short notes:
Wafer cleaning process 05
Buried layer 04
Package sealing 05
Q.3 Discuss wet chemical etching technique. 06
With necessary schematic, explain in detail the molecular beam epitaxy
process.
08
Q.4 Discuss the boron diffusion technique in detail. List the advantages. 06
List the types of Lithography techniques. Explain the Optical Lithography
technique with relevant example.
08
Q.5 Discuss electron beam lithography technique with a neat sketch. 06
Discuss Chemical vapour deposition technique for the deposition of
silicon nitride films.
08
Q.6 Write a note on the failure mechanism in metal interconnects. 06
With a neat schematic, explain the magnetron sputtering technique. 08
Q.7 Write a note on Printing Grid Array. 06
With relevant diagrams, explain the making sequence and process flow
of p-MOS devices.