Why positive PR is the better than negative PR in VLSI

[empkth]

As attached, I know basic concept between Positive and Negative PR

But, I confirm this message; Negative resists were popular in the early history of integrated circuit processing, but positive resist gradually became more widely used since they offer better process controllability for small geometry features. Positive resists are now the dominant type of resist used in VLSI fabrication process.

1. Why Positive PR is the better than negative PR in VLSI?
2. Why Positive PR is the better than negative PR about "Resolution" ?

R=K*λ/NA (Rayleigh criterion)

Please.. Answer to me, I'm so curiosity... with Engineertic answer..

 

[davenn]

Hi
welcome to PF

Negative resists were popular in the early days of integrated circuit processing. Positive resist slowly became more widely used since they offer better process control for small geometry features as dies became higher density. Positive resists are now the main type of resist used in VLSI fabrication processes.


Dave

 

[empkth]

Thanks to Dave!

But What is the meaning of higher density? So, higher density... After what?

Please.. Add to logical answer.

 

[davenn]

higher density = more transistors etc in a given area of the die