He2 60–90 nm photon source for investigating photodissociation dynamics of potential X-UV resists

Abstract

Recent discovery of laser sources around 50 nm stimulated research on the development of resists for high-resolution lithographic applications in the spectral region from 50 to 100 nm. It is very possible that the problems related to the application of 157 nm lithography (out-gassing, defect-free thin films, compactness of optical materials) will be avoided in this spectral region. In this work, out-gassing experiments were carried out using an epoxy novolac-based resist around 70 nm. The resist was selected because of its sensitivity in the X-UV spectral region. The main result is that resist out-gassing in this case is reduced in comparison to 157 nm. This is because, at 70 nm (17.7 eV), photofragments were produced from the dissociation of ionic excited electronic states, as opposed to 157 nm (7.8 eV), where excessive out-gassing is the result of direct dissociation from neutral electronic excited states.