Electron-beam direct-write

The current technological competition for practical fabrication of 0.5 - 1.0 pm feature is in between photolithography and electron beam direct writing, and between single layer and multi-level resist. For less than 0.5 pm, the use of electron beam writing with multilevel resist will be inevitable. Further developments in electron resists from the standpoint of both resist chemistry and process development will be necessary to establish the electron beam lithography. 

It is equally worthy to note that a resist based on hydrogen silesquioxanes (HSQs) and formulated in methylisobutyl ketone (MIBK) carrier solvent has recently been reported to have demonstrated pitch resolution down to 20 nm in a 30-nm-thick HSQ film with electron-beam direct-write lithography (exposure... 

H. Ito and E. Flores, Evaluation of onium salt cationic photoinitiators as novel dissolution inhibitor for novolac resin, J. Electrochem. Soc. 135,2322 (1988) H. Ito, Aqueous base developable deep UV resist systems based on novel monomeric and polymeric dissolution inhibitors, Proc. SPIE 920, 33 (1988). T. Aral, T. Sakamizu, K. Katoh, M. Hashimoto, and H. Shiraishi, A sensitive positive resist for 0.1 p,m electron beam direct writing hthography, J. Photopolym. Sci. Technol. 10, 625 (1997). 

In electron-beam direct-write lithography, the scanning electron beam of the exposure systems is focused to a small spot that is controlled [i.e., deflected and turned on and off (blanked)] by a computer as it is scanned across the surface of the resist film. Masks are not used in this exposure process. Two beam-forming approaches are employed. The first uses a Gausssian round beam. The second... 

In order to address the low throughput issues of electron-beam direct-write lithography, without multiple columns and the attendant complexity, electron... 

A. Nakayama, S. Okazaki, N. Saitou, and H. Wakabayashi, Electron beam cell projection lithogra phy A new high throughput electron beam direct writing technology using a specially tailored Si aperture, J. Vac. Sci. Technol. B 8(6), 1836 (1990). 

Alexe M., Hamagea C., Erfurth W., Hesse D., Gosele U. 100-nm lateral size ferroelectric memory cells fabricated by electron-beam direct writing. Appl. Phys. A 2000 70 247-251 Aoki T., Knrihara K., KnwabaraM. Fabrication of epitaxially grown PLZT patterned microstructures using a sol-gel method. Key Eng. Mater. 2003 248 61-64 Aoki T., Kurihara K., Kamehara N., Kuwabara M. Unpublished work... 

A precise positioning stage driven by friction with an ultrasonic motor provides a promising solution for an electron-beam direct-writing system for the next generation LSI, and has been realized by the optimum design of overall system using the concept described above. 

Hydrogel films of PEO (thickness 100 nm) can be irradiated with an electron beam to write patterns in the micrometer and sub-micrometer range. " The elearon-beam lithography is applicable to different sensitive polymers. The direct writing of patterns into a dry, spin-coated film of PNIPAAm was done by Vijay a Schmidt et investigated the possibilities... 

Fig. 39. Schematic showing the basics of cell projection. The desired beam shape is selected by steering the electron beam through the appropriate pattern in the aperture plate. By using a rectangular aperture the system can operate like a conventional direct-write e-beam tool, so any shape of pattern can be...

The experimental appearance energies of CH2OH+, 1080.6 kJ mol-1 (11.20 eV) and 1127.9 kJ mol-1 (11.69 eV), respectively, were measured in both cases by using a monoenergetic electron beam [68,69]. Because they have been directly identified with the enthalpies of reactions 4.21 and 4.22 at 298.15 K, we can write... 

Future Direct-Write Electron Beam Systems... 

As already discussed, there is an important case where resolution is determined by fundamental limitations of the electron optical system and not by electron scattering. This occurs with the high current shaped electron beams used in high throughput direct-write tools. The Coulomb interaction between electrons in these columns displaces the electrons from their intended trajectories and blurs the edges of the spot. As discussed above in connection to throughput, this effect, which is related to the Boersch effect (45) forces a compromise between throughput and resolution. 

Focused ion beams can be used to expose resist, to write directly diffusion patterns into semiconductor substrates, and to repair masks. These techniques can potentially simplify semiconductor device production and perhaps reduce cost. Many of the technological challenges with ion beams are similar to those encountered with electron beams, but the development of ion sources and focusing/deflection systems are at a much earlier stage of development so application to manufacturing is several years away. 

Electron beam resists to be used in direct wafer writing for submicron devices need significant improvement in sensitivity, resolution and dry etching durability. Multilayer resist (MLR) systems are now regarded as the most important technology to perform practical submicron lithography for VLSI fabrication (1-3). Many advantages in MLR compared with one layer resists (1LR) are listed here ... 

We attempted to use this increase in refractive index in fabricating polyimide optical waveguides. The fabrication of a fluorinated polyimide waveguide by the direct electron beam writing method is described in Section 4.3.2. We also investigated the changes in the refractive index of fluorinated polyimide films by synchrotron radiation. 7 The refractive index at a wavelength of 589.6 nm increased by 1.3% and the thickness decreased by 0.69% for fluorinated polyimide film after 30 min of synchrotron irradiation. From the XPS data the synchrotron radiation leads to production of a fluorine-poor surface. 

The refractive index of fluorinated polyimide can be controlled precisely by adjusting the election beam irradiation dose as described in Section 3.2.2, and this feature can be exploited in fabricating polyimide optical waveguides. This section describes fluorinated polyimide waveguides fabricated by the direct electron beam writing method. ... 

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