A theoretical analysis to estimate the effect of shot noise on CDU is induced from optical imaging perspectives combined with quantum theory, and is studied for 193-nm, EUV, and electron beam lithography. We found the CDU variation from shot noise is related to the number of particles absorbed in the printed area and to the image log slope (ILS). Hence, the CDU variation contributed by shot noise gets worse when the technology node advances from 45-to 32-, 22-, and 15-nm, EUV with higher ILS is no exception. For e-beam lithography, we are interested in the values of ILS calculated from array structures with different pitches, backscattering, wafer-stage movement, and raster-scan writing.

We have recently introduced Variable Pressure Electron Beam Lithography (VP-eBL), as a new approach for the fabrication of nanometer-scale structures on electrically insulating substrates. [1] This novel approach combines the high resolution patterning capability of electron beam lithography with the charge-balance mechanism of the variable pressure scanning electron microscope (VPSEM) to control charging effects during pattern exposure. VP-eBL eliminates the need for any of the additional materials or processing steps required to eliminate pattern distortion artifacts during high vacuum eBL patterning on such substrates. The nominal VP-eBL approach has been extended to allow patterning of wide variety of nanostructures combining liquid precursors (sol-gel, for example) -termed variable-pressure soft-electron beam lithography (VP Soft-eBL). [2,3] VP Soft-eBL is truly a facile approach for site-specific fabrication of organic, inorganic and hybrid solid-state nanostructures through a novel combination of electron beam lithography (eBL) and spin coating of liquid and sol-gel precursors, termed soft eBL (Fig. 1). By using eBL patterned resists as masks in combination with a low cost process such as spin coating, directed growth of nanostructures with controlled dimensions is achieved without the need for costly and difficult process step of etching ceramics. The highly versatile nature of the scheme is highlighted through the fabrication of nanostructures of variety of materials such as ferroelectric, optoelectronic and conducting polymeric materials at different length scales and spatial density on multitude of substrates (Fig. 2). VP Soft-eBL enjoys remarkable attributes of high resolution, registry, gentle nature of the process, versatility of materials systems and independence of substrate choice.In the process of developing VP Soft-eBL, we have learned considerable intricacies of VP SEM operation, eBL process under variable-pressure conditions, and their collective influence on both, science of lithography and its applications to nanopatterning. For example, we observe considerable influence gas pressure on shape, size and definition of e-beam pattern, possibly due to modification of sub-surface space-charge due to positive gas ions in the vicinity (Fig. 3). The presentation will highlight role of variable pressure in both, eBL and soft-eBL approaches.[4] References[1] B.D.