Thapar University 2006 B.Tech Electronics and Communications Engineering Microelectronics & ICs - Question Paper
Thapar Institute of Engineering & Technology
B.Tech ECE (3rdYear)
Final Term exam
EC029 (Microelectronics & ICs)
Thapar Institute of Engg. & Tech [Deemed University], Patiala
End semester Exam, Dec 2006 Microelectronics & I.C.s [EC-029] Subject Instructor: Urmi Agnihotri Max. Marks: 45 Max. Time : 3 hours
Note: 1.] Attempt any 9 questions. Each question carries 5marks.Dont over attempt.
2.] Use diffusivity of boron as 4*l0"3cm2/sec.
3.] See your answer sheets on 13th at 5.10pm in my room.
Ql. i.) Explain with help of diagram and chemical equations, Czochralski crystal growing technique.
ii.] List the various steps in the final manufacture of a wafer from the raw silicon.
Q2. i.] Write a short note on dry, HCl Dry, Wet, High-pressure and plasma oxidation.
ii.] Discuss any two oxide properties.
Q3. i.] Discuss plasma surface interactions.
ii.] What are plasma etchers and barrel reactors?
iii] Discuss side wall mechanism Q4. Write detailed note on the usage of silicon on insulators.
Q5. Write short notes on :
i.] Ion beam lithography ii.]Electrori beam lithography iii.] Optical lithography Q6. i.] What is range theory? Explain in detail.
ii.] Draw only the complete schematic of typical ion-implantation machine.
Q7. Explain in detail the causes imperfect yield.
Q8. Explain i.] Package types ii.] Thermal.design considerations
iii.] Mechanical design considerations iv.] Electrical design considerations Q9. Find the diffusivity from a known impurity profile. Assume that boron is diffused into n type Si crystal substrate with doping concentration of 1015 atoms/cm3, and also that the diffusion profile can be described by gaussian function. Using a diffusion time of 60 min, one obtains measured junction depth of 2 microns and a surface concentration of 1018 cm'3 Q10. Equilibrium concentrations of boron at solid and liquid interface are 10'3 and 10a atoms/cm3 respectively. If the boundary layer thickness is 0.0025mm, find the value of equilibrium segregation coefficient and effective segregation coefficient for a pull rate of 2.7mm/min.
Ql l.i.] Find the linear rate constant if the parabolic rate constant for wet oxidation is
0.287jun/h and the value of A is 0.226m.
ii.] Calculate the mean free path (in cm ) of the dopant if the pressure in the MBE chamber is 108 Torr.
Q12. i.] What is rents rule? Estimate the number of gates that can be included on a logic array chip, which is to be assembled in a 100 I/O package. Assume alpha =2.5 and beta =0.45.
ii.] Draw the sequence only for packaging starting from wafer preparation till test showing material and piece part.
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