VLSI Design Questions and Answers - Design Rules and Layout

1. Circuit designers need _______ circuits.
a) tighter
b) smaller layout
c) decreased silicon area
d) all of the mentioned

Answer: d
Explanation: Circuit designers in general prefer tighter, smaller layouts for improved performance and decreased silicon area

2. Process engineers want ______ process.
a) smaller
b) tighter
c) reproducible
d) non reproducible

Answer: c
Explanation: Process engineers want design rules which are controllable and reproducible process.

3. Maturity level of the process line affects design rules.
a) True
b) False

Answer: a
Explanation: Yes, the maturity level of the process line affects design rules.

4. Design rules does not specify __________
a) linewidths
b) separations
c) extensions
d) colours

Answer: d
Explanation:Design rules specify line widths, separations and extensions in terms of lambda

5. The width of n-diffusion and p-diffusion layer should be?
a) 3λ
b) 2λ
c) λ
d) 4λ

Answer: b
Explanation: The width of n-diffusion and p-diffusion should be 2λ according to design rules.

6. What should be the spacing between two diffusion layers?
a) 4λ
b) λ
c) 3λ
d) 2λ

Answer: c
Explanation: The spacing between two diffusion layers should be 3λ according to design rules and standards

7. What should be the width of metal 1 and metal 2 layers?
a) 3λ, 3λ
b) 2λ, 3λ
c) 3λ, 4λ
d) 4λ, 3λ

Answer: c
Explanation: The width of the metal 1 layer should be 3λ and metal 2 should be 4λ.

8. Implant should extend _______ from all the channels.
a) 2λ
b) 3λ
c) 4λ
d) λ

Answer: a
Explanation:Implant for a n-mos depletion mode transistor should extend minimum of 2λ from the channel in all the directions

9. Which type of contact cuts are better?
a) buried contacts
b) butted contacts
c) butted & buried contacts
d) none of the mentioned

Answer: a
Explanation: Buried contacts are much better than butted contacts. In butted contacts the two layers are joined together or binded together using adhesive type of material where as in buried contact one layer is interconcted or fitted into another.

10. Which design method occupies or uses lesser area?
a) lambda rules
b) micron rules
c) layer rule
d) source rule

Answer: b
Explanation: Micron rules occupies or consumes lesser area. 50% of the area usage can be reduced by using micron rules over lambda rules