Ion Exchange of Organic Ionic Compounds in Photoresist

Abstract

Organic ionic compounds, such as photo-acid generators (PAGs) and photo-decomposable quenchers (PDQs), are solvated in organic solvents. During this process, organic ionic comounds can be solvated only in an associated salt form or both in an associated salt form and a dissociated ionic form. In order to understand this behavior, we carried out (1) the binding energy calculation of photo-acid generator (see, Figure 1) in various solvents, (2) the Job plots with ¹H NMR spectroscopy for detecting the dissociated anions of organic ionic compounds by a bidentated hydrogen bonding, and (3) GCIB-SIMS analysis to monitor the distribution of cations and anions along the depth of coated photoresist layer. Based on the computational and experimental results, we propose that organic ionic compounds are solvated in both an associated salt form and a dissociated ionic form in equilibrium state resulting in ion exchange of cations and anions in mixed organic ionic compounds.