A new environmentally stable protective group for deep UV resists: Methoxy(tetrahydropyranyl) ether

Deep UV photoresists are designed to be used in the manufacturing of highly integrated chips (>16 Mbit). They differ from the conventional photoresist s in their principal chemistry. The vast majority of positive deep UV resis ts are based on protected poly(hydroxystyrene) resins and photochemical aci d generators (PAG). They rely on photochemically induced acid-catalyzed rea ctions (chemical amplification) to generate the desired pattern and meet th e high-sensitivity requirements. It turned out that the type of the acid la bile protective group is of paramount importance for the performance of the resists. It has to be stable enough not to be cleaved by the weakly acidic phenol at room temperature, but has to be labile enough to be cleaved read ily even at the top of the resist where portions of the generated acid may be neutralized by airborne bases. Selection criteria for useful groups and the performance of the very well suited protective group methoxy(tetrahydro pyran) are described in this paper. (C) 2000 John Wiley & Sons, Inc.