Investigation of lithographic performance for 120-nm and sub-120-nm gate applications of advanced ArF resists based on VEMA co-polymers

Abstract

ArF lithography is the current ramp-up technology for next generation devices. However, some manufacturing issues still remain when considering the resist design for the most advanced processes. Several polymer platforms have been proposed, among them, Methacrylate, CycloOlefin-alt Maleic Anhydride, and even pure Cyclo-Olefin. More recently, Vinyl-Ether Maleic Anhydride (VEMA) polymers have demonstrated potential in terms of both lithographic properties and etch capabilities. In this paper, the evaluation of some advanced samples of VEMA resists for 120nm and sub-120 nm gate applications will be discussed. The various criteria investigated for this study were; focus and exposure latitude for 120 and 100 nm lines (1/1.5 L/S to isolated lines), Iso-Dense bias, Line End Shortening (LES), Line Edge Roughness (LER), masking linearity, BARC compatibility, sensitivity to PEB temperature and electron beam, and finally etch resistance. Additionally some process optimizations were tested in order to minimize Iso-Dense Bias and the LER of the resists (See figure 1). In fact, this latter parameter has been a major focus of this work in improving the VEMA resist chemistry since its introduction and preparing it for device manufacture. The results obtained when varying parameters such as resist formulation, development conditions will be reported and so will demonstrate the current maturity of the most advanced VEMA samples.