VLSI TECHNOLOGY

VLSI TECHNOLOGY
SEM V, 2012-13
B.TECH
UTTARAKHAND TECHNICAL UNIVERSITY
(UTU)

 Time: 3 Hours

Total Marks : 100

Attempt any two questions:

1. What do you mean by epitaxy? Explain vapor phase epitaxy with its basic transport process.
2. Explain the diffusion controlled case and reaction controlled case with the help of Deal Grove's Model
3. How do you obtain MGS from pure silicon? Give all the reactions that take place during the process.
4. Why packaging is required? Explain flip chip technology?
5. What is Bridgeman method? Give the limitations of the Bridgeman method.
6. What do you mean by Reynolds number? How Reynolds number shows the flow of gas?

Attempt any four questions:

1.  Explain the MBE process in detail.
2. What do you mean by photoresist? Explain the various types of photo resists.
3. Explain the kinetics of wet etching. How gold is etched?
4. What is CZ - method? Explain along with its advantages and disadvantages.
5. Give Fick's first law and second law of diffusion.
6. What are the various types of defects in crystal structure, explain.

 Attempt any two questions:

1.  Explain the basic working principle of ion implantation process with all necessary equations. Compare between the diffusion process and ion implantation process.
2. Explain the various types of diffusion with the help of figures.
3. Explain X- ray lithography process. How will you calculate the blur?

 Attempt any two questions:

1. What do you mean by segregation coefficient (m)? Explain with figures slow diffuser and fast diffuser graphs for m<1 and m >1.
2. Explain optical lithography. In an optical lithography, the proximity printer operates with a 10 um mask wafer gap and wavelength of 430 nm, another printer uses 40 um mask water gap and wavelength of 250 nm. Calculate and show whose resolution is higher.
3. Derive the linear rate equation and parabolic rate equation for Si oxidation process.

 Attempt any two questions:

1.  What do you mean by etching process? Explain all the etching process in brief with neat diagram.
2. What do you mean by yield in VLSI? How you can have the products with overall high yield? Explain the trade-off also to achieve the high yield.
3. How a NPN transistor can be fabricated? Explain all the steps of fabrication. Also, compare it with NMOS fabrication.

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