Exploring the ultimate resolution of positive-tone chemically amplified resists: 26 nm dense lines using extreme ultraviolet interference lithography

Abstract

Interference lithography ͑IL͒ ͓Yen et al., Appl. Opt. 31, 2972 ͑1992͔͒ based on reflective optics, and utilizing extreme ultraviolet ͑EUV͒ light from an electron storage ring, can be used to pattern structures with periods below 70 nm ͓Solak et al., Appl. Phys. Lett. 75, 2328 ͑1999͒; Ali et al., Microelectron. Eng. 65, 454 ͑2003͔͒. Previously achromatic interferometers with EUV transmission diffraction gratings were also used for this purpose ͓Wei et al., J. Vac. Sci. Technol. B 12, 3648 ͑1994͔͒, and recently we have printed sub-50 nm high quality periodic structures in poly͑methylmethacrylate͒ exposed with transmission-grating EUV interference lithography ͑EUV-IL͒ ͓Solak et al., Microelectron. Eng. 61, 77 ͑2002͒; Solak et al., ibid. 67-68, 56 ͑2003͔͒. With this technique, two-dimensional patterns are easily achievable using multiple diffraction gratings. Both types of EUV-IL have been implemented on one of the undulator beam lines at the University of Wisconsin-Madison Synchrotron Radiation Center electron storage ring because this undulator source provides a tunable and coherent beam of radiation well suited for IL studies. In this article, both exposure methods were applied to explore the ultimate resolution of two positive-tone chemically amplified resists supplied by the Shipley Corporation. We have demonstrated the printing of features as small as 26 nm line and space in Shipley XP9947W-100 resist. The present results demonstrate the fine quality of the above-mentioned EUV-IL techniques to test resist formulations for high-resolution patterning, and we provide the experimental setup and discuss the observed results.

High performance resist for EUV lithography

“…4. The negative pattern of 35 nm L/S (70 nm pitch) was printed using transmission-grating EUV Interference Lithography (EUV-IL) tool [24]. Depending on the electron beam current in the storage ring, typical exposure time never exceeded 140 s. The scanning electron micrographs of positive tone patterns for the resist are shown in Fig.…”

Nanopatterning with interferometric lithography using a compact /spl lambda/=46.9-nm laser

“…1(a). Beam interference gives rise to a sinusoidal intensity pattern of period , defined by the wavelength of the light and the grazing incidence angle according to (1) 1536-125X/$20.00 © 2006 IEEE Increasing the incidence angle of the incoming beam on the mirror effectively results in an increased angular separation between the two interference beams and the corresponding decrease in the interference fringe spacing. The sinusoidal intensity pattern produced by the interference has maxima and minima that are functions of the intensity of the two beams and , and the coherence properties of the source.…”

Partially coherent extreme ultraviolet interference lithography for 16nm patterning research

“…Nonimaging EUV interference lithography ͑EUV-IL͒ tools have been developed at synchrotron facilities for photoresist research. [1][2][3] However, the rate of progress continues to be photon limited, and the potential for a compact tool utilizing a partially coherent plasma source is of growing interest. [4][5][6] To accommodate the relatively low coherence from an EUV plasma source, a combination of filtering and an achromatic design is advantageous.…”