Talk:Photolithography
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I believe that EUV refers to smaller wavelengths than mentioned in the article. It would be helpful if someone knowledgeable on the subject to correct this. --Matt Stoker
In my experience, sodium is avoided like the plague in a fab, so I doubt that sodium hodroxide would be used for the developing step, but would expect to see potasium hydroxide there. Gentgeen 15:02, 24 Mar 2004 (UTC)
- That's true, sodium is totally off limits in CMOS foundries. I've updated the article to mention metal-ion-free developers. 64.119.159.126 04:09, 25 Mar 2004 (UTC)
Acid creation
Novolak/DNQ resist systems are made up of a backbone resin called Novolac. Novolac has a certain solubility in alkaline fluids (developer). The solubility can be decreased by adding DNQ. Upon exposure the DNQ is transformed into an ICA acid which increases the solubility to levels above that of the resin. I think it is not only the creation of an acid that makes changes the solubility. There is also some reaction/attraction between the DNQ and novolak that reduces dissolution.
The resist technology described here is based on so-called Novolak/DNQ systems. These work fine -and are still used- for wavelengths downto 365 nm. However when industry moved to lower wavelengths to make feature sizes even smaller they changed there resist technology to chemically amplified resist which has a slightly different working principle.