Variation with Composition of the Intrisic Sensitivity of Halogen-Substituted Styrene Copolymers to Electron-Beam Radiation

In the polymer literature (Handbook of Polymer Science and Technology, ed. N. P. Cheremisinoff, Marcel Dekker, New York, 1989, vol. 1, p. 307) a simple equation has been derived to estimate the lithographic sensitivity of a copolymer of known composition and molecular weight from the constituent homopolymer values. Sensitivity has often been equated with the reactivity parameter D(g)M(w) where D(g) is the gel dose and M(w) the weight-average molecular weight of the polymer. This report demonstrates that the use of the reciprocal reactivity (D(g)M(w))-1 leads to a clearer interpretation of the lithographic results and that furthermore, the conclusions drawn from earlier analyses neglect the consequences of co-operative action between differing monomer units within copolymers.