Resist process development for sub-100-nm ion projection lithography

Abstract

Ion projection lithography (IPL) is designed to realize resist structures on the wafer plane well below 100 nm. Patterns from a stencilmask are printed with 4× reduction using an electrostatic lens system. First exposures with the IPL Process Development Tool [Proc. SPIE 3997 (2000)] will start within the fourth quarter of this year. In the meantime, a baseline resist process for i-line, DUV and e-beam resists has been established with exposures on a 1× masked ion beam lithography (MIBL) tool at IMS-Vienna . The results as obtained with 75-keV He + ions are compared with experiments using a 30-keV e-beam writer at IMS-Chips, Stuttgart. Resists were provided by Shipley and Clariant. For the first time, through close interaction with industrial resist companies, ion beam resist materials are available and characterized with well tailored sensitivities in order to vary the IPL exposure dose between 0.4 and 3 μC/cm 2 (double the dose to clear large areas value). These materials will be essential to study and establish the required IPL resist exposure dose for sub-100-nm structures. We measured the sensitivities (dose to clear large areas), contrast curves as well as MIBL dose latitudes. With higher precision than previously done [J. Vac. Sci. Technol. B15 (1997) 2355] the contrast curves have to be established as input data for IPL simulations. The IPL sensitivity is lower by more than an order of magnitude, compared to 30-keV e-beam exposure. Our paper presents and discusses the results. For IPL resist simulations the Monte Carlo simulator SRIM 2000 [Ziegler et al., The Stopping and Ranges of Ions in Solids, Pergamon, New York (1985)] is used to obtain energy density distributions in C x H y O z resist materials. We are presenting and comparing point spread functions of 60 and 75 keV H + ions, He + ions and electrons.