Question

If a 25Ω diffused resistor is to be designed for an emitter resistor, determine the pattern in which it is fabricated?

(a) 20mil long by 5mil wide

(b) 25mil long by 1mil wide

(c) 5mil long by 1mil wide

(d) 16mil long by 4mil wide

I have been asked this question in homework.

Question is from Active and Passive Components of IC topic in portion IC Fabrication of Linear Integrated Circuits

Answer 1

For a 25Ω diffused resistor used in emitter configuration:

The pattern dimensions are determined by resistance formula:

R = ρ × (L/W)

Where L is length and W is width.

For a low resistance like 25Ω, we need:

- Small length L

- Large width W

This results in a wide, short rectangular pattern.

Answer: (c) 5mil long by 1mil wide