1 August 1991 Wet-developed, high-aspect-ratio resist patterns by 20-keV e-beam lithography
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In order to enhance the contrast of the e-beam negative resist, Suga has combined DUV and e- beam exposures. This application has been further extended to the high sensitive three component SAL 601 resist. As the absorption phenomenon of UV light by resist layers obeys Lambert's law, the optically deposited energy density in a photolithographic process decreases through the photoresist layer from top to bottom. In contrast, for a 20 KeV imaging process of an electron-sensitive resist, the energy deposition profile corresponds to that of the particles implanted in the resist, i.e., a Gaussian profile centered at 2 to 3 micrometers in depth. Therefore, the deposited energy density throughout a 1 micrometers thick resist layer is an increasing function from the surface to the resist to the substrate. The combination of both exposure modes provides an almost constant density of deposited energy throughout the layer depth, giving rise to better profiles. This paper discussed the experimental characteristics of the DUV flood exposure which are required for the process to work correctly. As DUV flood exposure aims to treat the top part of the resist, making it more sensitive to the electron beam than the bottom part, it is of prime important to adjust the absorption coefficient of the resist, and consequently the wavelength spectrum of the light, so that light is principally absorbed near the surface and does not insolate the bottom of the resist.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Andre P. Weill, Andre P. Weill, Gilles R. Amblard, Gilles R. Amblard, Frederic P. Lalanne, Frederic P. Lalanne, Jean-Pierre Panabiere, Jean-Pierre Panabiere, "Wet-developed, high-aspect-ratio resist patterns by 20-keV e-beam lithography", Proc. SPIE 1465, Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing, (1 August 1991); doi: 10.1117/12.47363; https://doi.org/10.1117/12.47363

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