A Negative Aqueous Developable Electron-Beam Resist Under Deep UV Exposure

Abstract

In the years to come, on-line semi-micronic lithography will be achieved via electron beam or deep UV exposure. Each of these techniques presents advantages (flexibility of direct writing and rapidity of exposure, respectively). The best choice for the process technologies would be the complementary use of both techniques. It appears interesting to us to select a resist which is sensitive to both of these exposures. The good results (in terms of resolution and sensitivity) obtained with the Shipley SAL 601 resist under a-beam exposure and the analysis of its absorption spectrum have led us to select this particular resist. This paper presents the results we obtained by exposing a 500 nm thick layer of Shipley SAL 601 deposited over a SiO2 layer in the vaccum contact printing mode. Three types of beams have been tested; two of them from a Fusion Illuminator 100 system (centered at 220 and 260 nm, respectively), one from a KrF excimer laser (248.4 nm) and the fourth from a Karl Suss MA6 (310 nm). The Scanning Electron Micrographs of the patterns obtained with the deep UV process are explained in terms of the physical and chemical properties of the resist and of the deep UV source characteristics.