Imaging Resist application

Fig. 36. Representative bilayer resist systems. Both CA and non-CA approaches are illustrated (116—119). (a) Cross-linking E-beam resist, 193-nm thin-film imaging resist (b) acid-catalyzed negative-tone cross-linking system (c) positive-tone CA resist designed for 193-nm applications and (d) positive-tone...

The imaging properties of PVTMSK were studied by spin coating 350-nm-thick films on silicon wafers or on silicon wafers precoated with a 1.5-(xm-thick layer of hard-baked photoresist, exposing them to mid- or deep-UV radiation through a chromium-on-quartz lithographic mask, and developing the pattern as described earlier. This scheme was used to test the intended application of PVTMSK as an imaging material for two-layer resist applications. The densest patterns resolved were composed of l-(xm coded lines and spaces. 

PMMA has been the most studied of the e-beam positive resist polymers. Images approaching 200 A have been resolved in PMMA. In addition, PMMA has excellent coating and development properties for resist applications. However, the low sensitivity of PMMA (8 x 10 Ccm at 20 keV) and the poor resistance to fluorine plasmas have minimized its use in practical applications other than mask making. 

To date, we have exercised these materials in basically three types of multilayer lithographic applications (1) as short wavelength contrast enhancing layers, (2) as imagable 02-RIE resistant materials in bilayer processes and (3) as radiation sensitive materials for multilayer, e-beam processes. 

A rapidly increasing number of publications on polysilanes documents current interest in these polymers (JJ. Polysilanes are potentially applicable in microlithography as high resolution UV-resists (2J, imageable etch barriers ), or contrast enhancement layers (4). They have been successfully used as precursors to Si-C fibers (5J and ceramic reinforcing agents ((L). Polysilanes have also initiated polymerization of vinyl monomers (J ). Doping of polysilanes have increased their conductivity to the level of semiconductors (8). Very recently polysilanes were used as photoconductors (9) and non-linear optical materials (10b... 

The lithographic applications of a double-layer resist system in which the poly[p-(dimethyldiphenyldisilanylene)phenylene] film (0.2 ym thick) was used as the top imaging layer have been examined (K. Nate, T. Inoue, H. Sugiyama and M. Ishikawa, J. Appl. Polym. 

Other Printing Applications. There are a number of lower volume applications of photopolymer chemistry to the printing industry. Some of these include the production of tactile images (raised Braille patterns) (47) and screen stencil resists... 

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