Why positive PR is the better than negative PR in VLSI

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Discussion Overview

The discussion centers on the comparison between positive and negative photoresists (PR) in the context of VLSI (Very Large Scale Integration) fabrication processes. Participants explore the advantages of positive PR, particularly regarding process controllability and resolution in small geometry features.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants note that negative resists were historically popular in integrated circuit processing, but positive resists have become dominant due to better process controllability for small geometry features.
  • There is a specific inquiry about why positive PR is considered better than negative PR in terms of resolution, referencing the Rayleigh criterion (R=K*λ/NA).
  • One participant seeks clarification on the term "higher density," asking for a logical explanation of what it entails in the context of VLSI.
  • A later reply defines higher density as having more transistors in a given area of the die.

Areas of Agreement / Disagreement

Participants generally agree on the historical context and current dominance of positive PR, but there are unresolved questions regarding the implications of "higher density" and the specific advantages of positive PR in terms of resolution.

Contextual Notes

The discussion does not resolve the specific advantages of positive PR over negative PR regarding resolution, nor does it clarify the assumptions behind the term "higher density." There is a reliance on the Rayleigh criterion without further elaboration on its implications.

empkth
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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..
 

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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
 
Thanks to Dave!

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

Please.. Add to logical answer.
 
higher density = more transistors etc in a given area of the die
 

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