The minimum feature size for the LSI circuit geometry will reach 20 nm in the upcoming 45 nm technology node. In order to achieve this target, various new lithography technologies, such as Electron-beam (EB) and Extreme-ultraviolet (EUV) lithography, are now being intensively developed. However, as shrinking gate length, line edge roughness (LER) of fabricated resist patterns becomes one of the most significant issues [1][2][3]. For the resist material aspect, the application of compounds with low molecular weight and/or narrow polydispersity may be one of the key concepts to dissolve this issue due to its reduced molecular weight and controlled structure [4][5][6][7]. We have reported the characteristics and LER properties of molecular resists based on low molecular weight polyphenols as a chemically amplified (CA) positive-tone EB resist [8][9]. In this paper, new molecular resist based on cholate derivatives for EB lithography will be reported. Figure 1 shows the structures of two cholate derivatives (C2ChDM and C2E) prepared for resist base matrix. The etch rates of C2ChDM and C2E, which were measured under CF4/CHF3/He mixed gas process, were almost the same as polyhydroxystyrene (PHS) as shown in Fig. 2. From the dissolution rate measurement by using alkaline developer, the model resist samples formulated with C2ChDM or C2E as base matrix and photo-acid generator originated from onium-salt (resist-A and B, respectively) showed good sensitivity and the dissolution behavior of common CA positive-tone resist. Furthermore, the FT-IR spectra of resist-A and B films unexposed and exposed with the EB lithography tool was measured. A cleavage reaction of acetal bonds occurred by EB irradiation and PEB treatment as the characteristic signals for acetal bonds at around 949 cm-' and 1735 cm-' became weak. From the dissolution rate measurement and the FT-IR spectra changes, we confirmed that the resist-A and B could work as common CA positive-tone resist. The evaluation results with the resist-A and B by using EB exposure tool indicated the resolution of 120 nm lines and spaces pattern as shown in Fig. 4. References[1] C.
The effect of m/p-cresol novolak molecular-weight-distribution (MWD) and dissolution inhibitor structure on resist performance were investigated. A novolak resin richer in p-cresol ratio gave a large dissolution inhibition capability of polymeric dissolution inhibitor, tetrahydropyranyl (THP) protected-polymeric dissolution inhibitor. In particular, a high molecular-weight novolak resin richer in p-cresol ratio was regarded as an effective matrix of a chemical amplification (CA) positive resist. THP protectedphenolic compounds with extended backbone structures showed a large dissolution inhibition. The resist with MWD controlled resin and a THP-protected phenolic compound can achieve high resolution patterns (100-nm contact holes ) with high sensitivity (6.0 µC/cm2).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.