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9 July 1992 Scanning tunneling microscope lithography: a viable lithographic technology?
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A steered beam lithography will represent an essential part of the technology to meet the future need for ultra-high resolution mask making and direct write. Conventional high voltage e-beam lithography is being developed to meet these challenges. However, there are a number of physical limitations (proximity effects, resist sensitivity) which must be overcome. To do so will prove to be extremely expensive if in fact these problems can be overcome. There are significant advantages in going to extremely low energies in e-beam lithography. Proximity effects are eliminated although the electron-optics become more exacting. The need to focus a low energy e-beam can be eliminated by maintaining a sharp tip close to a surface as in a scanning tunneling microscope (STM). We have demonstrated technologically useful lithography with the STM operated with 4 - 50 V between tip and sample. Patterns have been defined in e-beam resists and by selective oxidation of semiconductor substrates under the action of the STM tip. In both cases the pattern can be transferred into the substrate with a dry etch. Sub 50 nm resolution is routine on a variety of substrates. A viable lithographic technology has been demonstrated in the research laboratory. However, several key issues must be addressed to develop a technologically viable lithography system compatible with existing microfabrication practice. These issues include: registration using the imaging properties of the STM for alignment, pattern accuracy and throughput. Advances in STM speed are described and suggestions made for improving lithographic performance with multiple sharp tips (each with an independent servo loop). The potential pay-off is high as a low voltage lithography tool will involve significantly less capital investment (and support cost) than the next generations of high voltage e-beam lithography tools.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christie R. Marrian, Elizabeth A. Dobisz, and John A. Dagata "Scanning tunneling microscope lithography: a viable lithographic technology?", Proc. SPIE 1671, Electron-Beam, X-Ray, and Ion-Beam Submicrometer Lithographies for Manufacturing II, (9 July 1992);

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