Influence of underlayer on development of chemically amplified photoresist film in tetramethylammonium hydroxide (TMAH) aqueous developer

The interactions between the underlayer and photoresist significantly affect the dissolution behavior and patterns formed in the photoresist during development. Therefore, it is important to analyze the dissolution behavior of a photoresist with an underlayer. In this study, the dissolution behavior of poly (4-hydroxystyrene) films partially protected with tert-butoxycarbonyl groups and containing a photoacid generator (PAG) and photodecomposable quencher (PDQ) in a tetramethylammonium hydroxide aqueous solution is investigated using a quartz crystal microbalance. Triphenylsulfonium nonaflate and triphenylsulfonium salicylate are used as the PAG and PDQ, respectively. The underlayer has a complex influence on the dissolution behavior of the photoresist films during development. In particular, the underlayer significantly affects the formation of the transient swelling layer and dissolution kinetics at an exposure dose close to the photoresist sensitivity, namely, at the critical exposure dose for solubilizing the photoresist films.