Aqueous phase silylation a new route to plasma developable high resolution resists

A novel O 2/RIE developable photoresist system with aqueous phase silylation of the exposed areas is presented. The silylation includes a spontaneous crosslinking reaction between the anhydride groups of the base resin and the aminosiloxane silylating reagent. The silylation leads to a considerable growth of the film thickness which is promoted by higher exposure dose, acidity of the exposed resist, normality of the aminosiloxane solution, silylation time and temperature. The system demonstrates several benefits such as fast silylation with existing equipment (puddle development track) at room temperature, high etch resistance of the silylated layer against O 2/RIE (same as polyphenylmethylsilane), possibility of water inspection after silylation and applicability of the same resist formulation for 366 nm and 248 nm. First i-line stepper experiments gave 0.5μm lines and spaces with an aspect ratio of 4.5.