RTU 2016 Question Paper Semester VIII Electronics and Communication Engineering IC Technology

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B.Tech. VIII Semester (Main) Hxamination,ApriUMay zDfi
Electronics And Corumunication Engg.
8EC1A- IC TechnologY

Time : 3 Hours Maximum Marks : 80
Min. Passing Marks : 24

Instructions t0 Candidates:
Attempt anyfive questions, selecting one qr,testionfrom eoch unit. All questions
carry equal marks. (schematic diagrams mt;:;t be shown wherever necessary.
Any daia ),ou kel ruissing suitably be assumetl and stated clearly-.)
units of'qt,tantities used/calculated musi be stated clearly.

Unit - I
1. a) Explain the yarious defects in crystal with appropriate equation and diagram
(6)
b) How EGS is obtained tiorn iVICS. Also draw the block diagram for the
production olEGS, and also rvrite its chemical reaction. (6)
c) Find.out thc concentration of oxygen in crystal at a fraction solidified_of 0.4
the nxygen concentraticln at the Iop eii crystal- i.e at-X:0.05, C,:1.3x10r3
atom/c# segregation coeftjcient lbi oxygen to be 0.25 $)
OR
1. a) Draw the block diagram of lIoat zone growth technique and also show the
four point probe tecfinique fbr resistance measurrnent (6)
b) What are tfue various steps for wafer preparation. Explain each term in detail
(6)
c) Aboron doped crystai is measrirccl at it's seed end with a four-point probe of
spacing lmm, resistance is 10O . What is the seed and doping andthe expected
reading at 0.95 fraction solified (4)

88802U2016 (1) [Contd...

Unit - ll
2' a) Derive lick s law with its proper analyrrcai solution. Also write the boundary
b) An n+ diffusion p ggi{orrn*9 iT,g,:.p-r-ype silicon iraving a unifonu dcpant
concentration of 5x 1a23 atom/m3. lt the dopant concentrettu
in the 96 ut ov"
the wafer surface is nraintained constant dii11;l;;;;#;;d'p.o..s,
30ry1q, cql.ulate the
time is
*ryt! of nLype diffusion" +h;;rf.iii.o"mcienr is
5x16-rz m2lsec and erfc(2.3):16_r-' (g)

OR
2" a) Explain Deal-Groove rnotiel of oxidation with proptrr equation (10)
b) Discuss the various ditfusion mechanrsm by whictr the impurities
rrvo in silicon
crystal 'rr ""''&;
Unit - III
3. a) What are various types of-CVD reactors (4)
b) what is autodoping and rrow can this be minirnizecr (s)
c) Explain chemical equilibrium and the law.ofMass action (7)

OR
3. a) Assume that the gas AIi is introduced inro a C VIJ cactLrr atrcl that the only
r
chemicai reaction that ocr:urs lrr the chamber is
r s . If the process
is run at I atom (760 to rr) and a temp or rdbori-=-:r:\
a-r-B
and reaches chemical
equilibrium. calculate the partial p.*rrui* ;i.;;;
constant for this reaction is given -by K(T):t
species? The vYs
''v equilibrium
.8;i 0;;;;;ii' (7)
b) Discuss various gyq.techniquer f,rr treposirion of sior. Arso srare the
parameters on which SiO, deposition
depends (e)

Unit _ tV v
4' a) Draw the flow chart for mask generation process. Expiain
proper explanation each term with
b) Distinguish between wet etching arrd dry ctching. Wliat is tlre role
in the contact of wet etching of a orr[]
(7)
c) Explain the working of positive photo resist and negative photo
positive photo resisigives higrr ,rsorrrtioii-"- resist .Why
(4)

OR
4. a) Given an actount of reactive ion etchirrg ciearly
staring the problems
associated with it (10)
b) Explain the projection printing with suitable
diagram (6)

888021",
a)

5. a) Write the fabrication process sequence for
D n-well CMOS Process
ii) Twin tub CMOS Process
Give an gomParison
b)Whatdoyouunderstand!VbipolarlCtechnology? (6)
between bipolar and CMOS technology

5. a) Write short note on any two t. : '""

I i
D LOCOSmethod , '

"
iii) Problemassociatedwithmetallization : .-
IC technology{6)
Explain the working difference between cMos
and bipolar
b) ".(5:2=191

oElQnr1 (3)