# VLSI Questions and Answers – Sheet Resistance

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This set of VLSI Multiple Choice Questions & Answers (MCQs) focuses on “Sheet Resistance”.

1. Area A of a slab can be given as ____________
a) t * W
b) t / W
c) L * W
d) L * t

Explanation: Area A of a uniform slab is given as the product of thickness t and width W of the slab. Its unit is (micrometer)2.

2. For 5 micron technology, What is the Rs value for a metal?
a) 0.03
b) 0.04
c) 0.02
d) 0.01

Explanation: For a 5 micron technology, the Rs value for a metal is 0.03. It is the standard typical sheet resistance values.

3. For 2 micron technology, what is the Rs value for polysilicon?
a) 10-40
b) 20-50
c) 15-30
d) 15-100

Explanation: For 2 micron technology, the Rs value for polysilicon is 15-30.

4. Which has higher Rs values?
a) n-diffusion
b) p-diffusion
c) n-diffusion & p-diffusion
d) none of the mentioned

Explanation: The Rs values for p-diffusion is 2.5 times greater than that of the n-diffusion.

5. For 1.2 micron technology, what is the Rs value for diffusion?
a) 20-40
b) 20-45
c) 15-30
d) 25-50

Explanation: For 1.2 micron technology, the Rs value for diffusion is 20-45.

6. What is the relationship between channel resistance and sheet resistance?
a) R = Rs
b) R = Z*Rs
c) R = Z/Rs
d) R = Rs/Z

Explanation: The relationship between channel resistance and sheet resistance can be given as R = Z*Rs. Sheet resistance is a measure of the resistance of thin films that are nominally uniform in thickness.

7. Z can be given as the ration of ___________
a) lower channel by upper channel
b) upper channel by lower channel
c) all of the mentioned
d) none of the mentioned

Explanation: Z (length to width) ratio can be given as the ratio of upper channel to lower channel. It is just a numerical quantity and has no unit.

8. Deposition of metal or silicon alloy can be done by ___________
a) sputtering
b) evaporation
c) sputtering and evaporation
d) deposition should not be made

Explanation: Deposition of metal or silicon alloy can be done by either sputtering or evaporation. Sputtering is a process whereby particles are ejected from a solid target material due to bombardment of the target by energetic particles.

9. Deposition of metal can be done by co-evaporation.
a) true
b) false

Explanation: Deposition of metal or silicon alloy can also be done by co-evaporation from the elements.

10. Processing of the device is better using ___________
a) polysilicon
b) silicides
c) polysilicon & silicides
d) none of the mentioned 