Effect of substituent groups of phenol derivative dissolution inhibitors on inhibition efficiency

This paper focuses on the inhibition efficiency of t-Boc derivatives of bis-phenols. Several t-Boc derivatives of bisphenols were synthesized and their inhibition effects were evaluated in novolac resin and poly (4-hydroxystyrene) (PHS). When the novolac resin was used as the matrix polymer, the inhibition effects were thought to be governed by both the hydrophobicity and molecular size of the inhibitors. On the other hand, in the case of PHS, the hydrophobicity of the inhibitor molecule was thought to be the dominant factor responsible for decreasing dissolution rates. In addition, the effects of the basic components of the developers were also investigated. Solutions of sodium hydroxide, tetramethylammonium hydroxide and tetraethylammonium hydroxide were employed as developers. The effects of the basic components on the dissolution rates of the resists varied with the matrix polymer of the resist. The dissolution rate of novolac resin was higher in NaOH solution than in the developers consisting of organic bases. However, the dissolution rates of novolac resin samples containing dissolution inhibitors were lower in NaOH solution than in developers consisting of organic bases. This phenomenon may be attributable to the hydrophilic properties of the cation of a developer.