E-beam lithography

An optically generated x-ray mask is itself one of the key features of LIGA, producing the necessary high contrast with a thick (>10 pm) gold absorber on materials membrane consist of low atomic number elements [27], The absorber mask is patterned using polymethyl methacrylate (PMMA) resists exposed by electron-beam lithography (e-beam) or from an intermediate mask that relies on an e-beam exposure... 

Electron-Beam Machines m The key to the technology is electrobeam (or E-beam) lithography. E-beam lithography is a technique for creating extremely fine patterns (much smaller than can be seen by the naked eye)... 

FIGURE 15.4 SEM images of vertically aligned MWNTs at (left) UV lithography and at (right) e-beam patterned Ni spots. (Reprinted with permission from [45]. Copyright (2003) American Chemical Society.)... 

Fig. 12.7 InGaAsP/InP multi quantum well semiconductor structure process (a) Si02 etch mask deposition (b) PMMA spin coating (c) E beam lithography and develop (d) Si02 etch (e) PMMA stripping (f) InGaAsP membrane etch (g) Si02 stripping (h) Chip flipping and bonding to sapphire (i) InP substrate etch (j) Adhesive etch...

E-beam (e-beam) lithography, 15 160 in compound semiconductor processing, 22 193... 

Although e-beam lithography can give excellent spatial control of functional microdomains, this direct-write patterning process is not time-efficient for large-area integration of functional devices. Techniques for rapid patterning of functional nanostructures are thus needed for real-time applications. Ober et al. [106-108] have successfully developed a novel block copolymer... 

Enhanced radiation sensitivity may be designed into polymer molecules by incorporation of radiation sensitive groups,and this is an important aspect of research in e beam lithography. 

High resolution negative resists are needed for masked ion beam lithography (MIBL) and for the fabrication of MIBL masks by E-beam lithography (EBL). The MOTSS copolymer resists were developed to obtain the resolution of fine features that a bilevel resist can best provide. The flexibility afforded by choosing the structure of the HS, the copolymer composition, and the molecular weight allows a resist to be tailored by simple synthesis adjustments to have the particular sensitivity and etch protection which best suits the application. 

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. 

To increase printing rates an idea is to develop parallel e-beam lithography [36,50-56]. This would use electrically addressable two-dimensional arrays of electron sources. Each source would be a field emitter inside a CMOS control element. The electron sources in this case are quite complex, having not only grids but also focusing electrodes [36],... 

The advantage of this approach is not only the free choice of surface stractures which can be created, the material contrast which can be realized by the combination of chemical lithography and amplification with SIP, but also the potential to bridge the gap in structural feature sizes ranging from the microscopic to the nano-scopic scale. Since the feature sizes reported are still limited to the features of the mask used, direct writing with a focused e-beam should result in patterned polymer brushes of features matching the size of the immobilized macromolecule. 

MLR systems offer many advantages in optical, e-beam, x-ray, and ion-beam lithography. An advantage common to all imaging methods is in enhancement of resist sensitivity. As the resolution and the aspect ratio requirements are separated in an MLR system, faster resists that are usable only for low aspect ratio images can now be candidates for the top layer. Other advantages of MLR systems differ from one imaging method to the other. They will be discussed separately. 

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