Photo Acid Generators (PAG) diffusion in Lithography  

Posting by R. Vogeleer on 12 Jan 2009 at 14:55:32.

I am looking for water diffusion and permeation properties of photo acid generators (PAG’s) in a thin polymer film. This is for a semiconductor lithography application.

Currently I use an experimental technique that enables us to get a ball park diffusion coefficient of a photo acid generator diffusing through a polymer into water flowing over the polymer surface (room temperature). In first odere, the experimental technique seems to give use reasonable results. However, we are interested in getting the temperature dependence (.Arrhenius relationship – activation energy) for photo acid generators (PAG’s) diffusion coefficient in polymer, including the chemical activity in the polymer as function of external moisture humidity. The temperature range of interest is from 20C to 70C (well below the glass transition temperature).

From a literature source, I got an activation energy estimate of 10-11 kcal/ mole. When I use this activation energy, I get a 1 order of magnitude increase in the diffusion coefficient over the temperature range from 20 C to 70 degrees Celsius. My impression is that this is a reasonable estimate, but I do not have an independent confirmation. I am very interested in getting your feedback.

20C – experimental diffusion coefficient ~ 5 E-19 m2/s
70C – calculated diffusion coefficient ~ 5 e-18 m2/s

More precisely, we are looking for the following permeant: TriphenylsulfoniumNnonaflate,
permeating in copolymer of 2-methyladamantane methacrylate and B-(gamma-butyrolactone) with a MW ~ 12000 and polydispersity of 1.7 (ie use reference as an example). I am also interested in the diffusion properties of this chemical in Poly Methamethyl Acrylate (PMMA). Assume a film thickness of 150 nanometer. We are interested in the activation energy over a temp range of 20 C to 70C.

Can this be simulated with your CheFEM simulation software and could you suggest us an indication of the outcome? Could you suggest us additional laboratory techniques for the semiconductor lithography and electronic devices under our consideration?

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