Electron lithography

As an alternative approach towards the above requirement, Somorjai introduced the method of electron lithography [119] which represents an advanced HIGHTECH sample preparation technique. The method ensures uniform particle size and spacing e.g. Pt particles of 25 nm size could be placed with 50 nm separation. This array showed a uniform activity similar to those measured on single crystal in ethylene hydrogenation. The only difficulty with the method is that the particle size is so far not small enough. Comprehensive reviews have been lined up for the effect of dispersion and its role in heterogeneous catalysis [23,124,125]. 

The conventional approach has been to take resists which were developed for electron lithography and apply them to x-ray lithography. To a first order, there is a strong correlation between the sensitivity of resist systems (positive or negative) to electron beam radiation and their corresponding sensitivity to x-ray radiation. Figure 11 shows a plot of the 20 kV electron beam sensitivity in... 

Fluorescence burst analysis, a variation of FCS procedures that has an optimum configuration for simple presentation, uses a uniform nanoscopic flow channel with an optically perfect ceiling, uniform cross section, and periodic electrodes that can now be constructed by careful electron lithography techniques.55 By application of controlled electric fields, uniform plug flow of solution through... 

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. 

The fabrication of LSI circuits, and of VLSI circuits in particular, requires patterns of micron and submicron dimensions, and consequently polymer resists with a high degree of resolution (1). So far the most frequently used positive electron resist has been poly(methyl methacrylate) (PMMA), which affords a high resolution power together with a relatively good thermal stability (2-4) A serious limitation of PMMA with respect to the efficiency of the electron lithography system is its low sensitivity to electron irradiation ( 10-5 - 10 4c/cm2). For the preparation... 

Hild, R. et al., Formation and characterization of self-assembled monolayers of octadecyltrimethoxysilane on chrominm Application in low-energy electron lithography, Langmuir 14, 342-346, 1998. 

Berger and J.M. Gibson, New approach to projection electron lithography with demon strated 0.1 p,m linewidth, Appl. Phys. Lett. 57, 153 (1990) S.D. Berger, J.M. Gibson,... 

Groves, T. R., Pickard, D., Rafferty, B., Crosland, N., Adam, D., and G. Schubert. 2002. Maskless electron lithography Prospects, progress, and challenges. Microelectronic Engineering 61-62 285-293. 

Figure 7. Structures imaged into 0.5 fim thick AZ PN114 by shaped beam electron lithography (Hitachi HL-700D, 30 keV). Process prebake 1 min 110 C, exposure 9.0 /xC/cm, PEB 2 min 110 C HP, development 0.18 N TMAH (puddle, 40"). Ex x>sure and development courtesy of IMS Stuttgart, Germany [34].

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