Microlithographic processes

Initiators based on halonium and sulfonium salts are used commercially in various microlithographic processes and in the coating industry. Onium salts were developed commercially as photoinitiators due to the lower sensitivity of cationic polymerizations to oxygen compared to radical polymerizations. Aromatic halonium and sulfonium salts with complex anions such as SbF6, AsF6 and BF4- do not initiate cationic polymerizations spontaneously, but must be activated by UV irradiation. 

Most importantly, such structures form spontaneously by mechanisms of supramolecular self-assembly rather than necessitating external manipulation, for example by microlithographic processing. The utilization of LLC surfactant and amphiphilic block copolymer phases is therefore a simple method to tailor directly the nanometer-scale structure, which undoubtedly defines the properties of the final product. 

For several years, many of the commercial positive photoresists have contained multifunctional, principally trifunctional, DNS derivatives, some examples of which are shown in Figure 5.44. They contribute to enhanced image stability during the image transfer step in addition to higher contrast and faster development in the microlithographic process. 

Renak, M.L., G.C. Bazan, and D. Roitman. 1997. Microlithographic process for patterning conjugated emissive polymers. Adv Mater 9 392—395. 

Mirror systems with the glass ceramic Zerodur can produce resolution capabilities of 500 line pairs per mm for microlithographic processes. This impressive performance, which allows a resolution of line widths of approximately 1 pm, is required for the technology of micro-chip production. It is used to project the desired semiconductor structures onto the silicon wafer. The Silicon Valley Group, formerly Perkin Elmer Corp. USA, has significantly influenced the race for powerful micro-chips, for example, with its Micralign series, by using Zerodur mirror substrates (see Fig. 4.68). This system al-... 

Fig. 4.68. Precise contour measurements of a mirror blank for microlithographic processes for powerful micro-chips...

Mirror systems with the glass ceramic Zerodur can produce resolution capabilities of 500 line pairs per mm for microlithographic processes. This impressive performance, which allows a resolution of line widths of approximately... 

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