Structural Effect of Photoacid Generators on Chemically Amplified Resist.

Abstract

The relationship between photoacid generator (PAG) structures, using N-sulfonlyoxy imide compounds, and their resist performance were investigated from the viewpoints of the efficiency of acid generation and the behavior of generated acid diffusion. The acid generation efficiency was monitored by the use of acid sensitive dye. The increase in the absorption coefficient of N-sulfonlyoxy imide at 248nm based on imide parts, rather than sulfonate parts, resulted in the increase of the efficiency, and then giving the higher photo speed on resist. In order to estimate the magnitude of the generated acid diffusion in resist film, the catalytic chain length, that is the turnover value, of the acid catalyzed t-BOC decomposition were determined. The turnover was decreased with the increase of the steric hindrance by altering the substituents of generated sulfonic acid, thereby lowering the photo speed, while improving the resist resolution. From these tendency, the control of the acid generation efficiency and the generated acid diffusion in resist film were influential to determine the resist performance. Furthermore, the product analysis on the photolysis of N-sulfonlyoxy imide compound, together with the calculation of the molecular orbital and the estimation of their interaction with poly(p-hydroxystyrene) (PHS), were carried out for a better understanding of the structural dependency. On the basis of the knowledge, the photolysis mechanism of N-sulfonlyoxy imide compound was proposed.