The document discusses two potential mechanisms for acid generation in acid generating materials: intramolecular and intermolecular. The intramolecular mechanism involves a single acid generating molecule absorbing a photon, which excites an electron and leads to transfer of the electron to a cation site, neutralizing the charge and forming an ionic acid. The intermolecular mechanism involves impact by a highly energetic particle on multiple acid generating molecules. This causes ionization, charge transfer and dissociation events across many molecules, producing protons and electrons that can be captured to form acids. Ultimately, the document argues that the two mechanisms are not really different, as materials should be viewed as one large molecule, and higher energies simply disturb

1. To the CAR generic
mechanism(s)
Hopefully, it is not oversimplified
Yehiel Gotkis

2. Two mechanisms of acid generation could be
anticipated
Itramolecular –
Acid yielding AG transformations triggered by photon (single or multi-) absorption proceeding all within the same AG
molecule, C+(AH)- :
C+(HA)- + hν -> C0---H+ A-
It must be a closely resonant process because the photon has to be absorbed entirely.
One of the electrons localized at the A - H bond is excited to a delocalized orbital, and it either recombines back to the
same orbital or finds its way to another potential energy minimum, which is highly likely to be located at the positively
charged C+, and neutralize its charge converting it to C0.
The intramolecular distance C0---AH0 , being the most probable bond to absorb the excessive energy, extensively
elongates leaving the delocalized electron, when it is located on the C0, no chance to return back.
At the same time the covalently bonded neutral AH fragment undergoes its own electron density and geometry
restructuring, converting the covalent bond to an ionic one becoming an acid:
HA -> H+ A-
Ultimately, it is the same story we discussed before, namely, the excitation promotes
transfer of one of the A-H electrons to the cation localized orbitals, neutralizing its
charge and field. The covalent A-H bond is converted to an ionic bond making the
---H+ A- to act as a strong acid.

3. Two mechanisms of acid generation could be
anticipated
Itermolecular –
Acid yielding AG transformation triggered by an impact of a highly energetic incident object(s) (photon(s), electron, I believe, even ion)
affecting an extended ensemble of AG and its neighboring species.
In this case, the high amount of energy, carried by the impacting object, produces more extended bonding “demolition”, including
numerous molecular and dissociative ionization events, charge transfers, geometry restructuring and so on. Among them, the
processes of interest are
General ionization, producing low energy electrons
M -> M+ + e
Specific dissociative ionization of species containing terminal C-H bonds, producing H+, like, for example, - CH2 – polymer sections:
- CH2 – -> = CH – + H+ + e
This kind of processes result in formation of the both species necessary to promote the AG acidification- low energy electrons to
neutralize the cation and protons to electrostatically stick to the anion forming the acid.
C+(HA)- + H+ + e -> C0---(AH)-H+
Ultimately we see the same story again, namely, excitation promotes transfer of the resist’s electrons to
anti- or highly excited orbitals allowing the AG to capture it, neutralize its cation and “provide” the anion
freedom to expand its electrostatic field around and lure a proton.

4. Are the two discussed acid generation
mechanisms really different? I think that NO.
• It is all the same because dealing with condensed phase materials we
should not forget that I general, there are no individual molecules
anymore there. The condensed material sample is one big molecule,
some bonds of it are covalent and other ionic, some strong (multiple
bonds) and other weak (Van-der-Waals bonding) and so on.
• The higher the incident energy, the larger the material volume
disturbed.
• In DUV we are like snipers, shouting a single bullet into the AG molecule
hoping that it will trigger the targeted transformation.
• In e-impact, EUV, Soft X-ray etc. we explode a huge volume of material and
hope that the AG molecule will selectively pick up the necessary stuff to
finally convert itself to an acid.