Measurement of Acid Diffasion from a Photoacid Generator in Polymer Solids by using Nile Blue A Base.

Abstract

In chemically amplified resists, acid diffusion from a photo-acid generator (PAG) is one of the important factors which control their efficiency. This paper reports observation and estimation of the acid diffusion from PAG (p-nitrobenzyl 9,10-dimethoxyanthracene-2-sulfonate, NAS, or 2,4-dinitrobenzyl tosylate, DNBT) in polymer solids (PMMA or PEMA) by using a diffusion-controlled acid-base reaction. Nile Blue A base used as a basic indicator changes its absorption peak by protonation. The rate constants and hence the diffusion coefficients of acids from the PAG in polymer solids were estimated from second-order reaction kinetics.

The Measurement of The Acid Diffusion In Vinyl Ether Crosslinked Photoresist by Impedance Method.

“…The second method is used generally to calculate the diffusion rate of the ion in liquid electrolyte such as battery. [ 10] [ 11 ] [ 12] This is first attempt to apply the method to photoresist film. Figure 3 shows Randles equivalent circuit of photoresist film regarded as solid electrolyte.…”

Photoacid Generation in Polymer Solids Induced and Observed with Near-Field Scanning Optical Microscopy.

“…A spectroscopic technique was previously proposed by Yamakawa et al [3], where the diffusion of the photoacid was analyzed using fluorescence from a pH sensitive dye, Nile Blue A (NBA), doped together with the PAG. The basic form of NBA is so reactive with acidic substances that its protonation proceeds irreversibly resulting in NBA cation except under basic condition [4].…”