Electron-beam lithography resists

In electron beam lithography, resist charging during electron-beam exposure can lead to image distortion and pattern placement error. A PAT (e.g.. 

First planar integrated circuits fabricated r Electron beam lithography demonstrated Dry film laminate resist introduced... 

Langer et al. [10] measured also electrical resistance of individual MWCNTs at very low temperatures and in the presence of a transverse magnetic field. As for the case of the microbundle, the CNTs were synthesised using the standard carbon arc-discharge technique. Electrical gold contacts have been attached to the CNTs via local electron beam lithography with an STM. The measured individual MWCNT had a diameter of about 20 nm and a total length of the order of 1 im. 

Electron Beam Lithography. LB PMMA films with thicknesses of 6.3 nm (7 layers) are sufficient for patterning a Cr film suitable for photomask fabrication. For ultrathin PMMA films the resolution (see Fig. 1) is limited by the smallest spot diameter available on MEBES I (1/8 pm). However, it is not possible to obtain this resolution if a thicker resist (>100 nm) is used under the same exposure and development conditions, which demonstrates that ultrathin resists are able to minimize the proximity effect. Also, since the radius of gyration of 188,100 Mw PMMA is about 10 nm in the bulk, and the thickness of the 7 layer film (6.3 nm) is less than 10 nm, it is reasonable to assume there must be an alteration of chain configuration in the ultrathin films. This will be particularly true when the post-deposition baking temperature of the multilayer films is less than the glass transition temperature (115°C), as is the case for the present experiments. In such a case, interdiffusion of PMMA chains between the deposited layers may not result in chain configurations characteristic of the bulk. 

Ultimately, resolution in electron beam lithography is set by the range over which the primary electrons interact with the resist. That is by the distance over which the low energy secondary electrons are created (the resist is exposed mainly by secondaries) and by the range of the secondaries in the resist. For thin resists, and thin substrates (thin compared with the primary electron penetration) this resolution limit has been measured to be about 12 nm (43). 

Thick organic polymer resist films are used for the conventional lithography. Their thicknesses are dozens to hundreds of nanometers. When a processing size becomes small and enters nanometer order in electron beam lithography, scattering of electrons in a resist causes various problems, such as the proximity effect. The variation in molecular mass of each molecule which forms the resist also reduces the resolution. If the ultrathin resist film of several nanometers thickness will be realized, the lithography of higher resolution will become possible. 

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