Electron beam lithography resolution

Vieu C, Carcenac F, Pepin A. Electron beam lithography Resolution limits and applications Appl Surf Sci 2000 164 111-7(7). 

Vieu, C., Carcenac, F., Pepin, A., Chen, Y., Mejias, M., Lebib, A., Manin-Ferlazzo, L., Couraud, L., Launois, H. Electron beam lithography resolution limits and applications. Appl. Surf. Sci. 164, 111-117 (2000)... 

Vieu, C., et al., 2000. Electron beam lithography resolution limits and apphcations. Applied Surface Science 164 (1), 111-117. 

Broers, A.N., Hoole Andrew, A.C.F., Ryan, J.M., 1996. Electron beam lithography— resolution limits. Microelectron. Eng. 32, 131-142. 

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. 

An alternative is to use electron beam lithography, whose basic resolution is of order 4 A. However, e-beam lithography is a serial addressing system, rather than a parallel system, so that we must write a 2D image as a series of lines, rather than a 2D pattern, and this takes a much longer time. 

In other studies on MOS structures, the two types of hysteresis, normal and abnormal, are suggested to arise from the ion displacement in the insulator and to the trapping at the interface states. The presence of site-radiation-induced polymerization has been used to provide increased film stability and has been described as an application for high-resolution electron beam lithography for the fabrication of microcircuitry. 

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). 

Sun, S., and G.J. Leggett. 2004. Matching the resolution of electron beam lithography by scanning near-field photolithography. Nano Lett. 4 1381-1384. 

New promising technologies for future electron-beam lithography applications based on pyroelectrically induced electron emission from LiNbOs ferroelectrics [22] were recently proposed [23], The developed system possessing micrometer scale resolution used 1 1 electron beam projection. The needed electron pattern was obtained by means of deposited micrometer-size Ti-spots on the polar face of LiNbOs. Another solution for the high resolution electron lithography may be found in nanodomain patterning of a ferroelectric template. 

Figure 10.20 shows a printed pattern that has nanometer resolution [11]. In this case a hard stamp of GaAs, formed by electron beam lithography and etching, was used. The metal coating consisted of a bilayer of Au (20 nm) and Ti (5 nm). The... 

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. 

I—Current Limit of Resolution for Electron-Beam Lithography... 

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