Poly resist system

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. 

While "conventional positive photoresists" are sensitive, high-resolution materials, they are essentially opaque to radiation below 300 nm. This has led researchers to examine alternate chemistry for deep-UV applications. Examples of deep-UV sensitive dissolution inhibitors include aliphatic diazoketones (61-64) and nitrobenzyl esters (65). Certain onium salts have also recently been shown to be effective inhibitors for phenolic resins (66). A novel e-beam sensitive dissolution inhibition resist was designed by Bowden, et al a (67) based on the use of a novolac resin with a poly(olefin sulfone) dissolution inhibitor. The aqueous, base-soluble novolac is rendered less soluble via addition of -10 wt % poly(2-methyl pentene-1 sulfone)(PMPS). Irradiation causes main chain scission of PMPS followed by depolymerization to volatile monomers (68). The dissolution inhibitor is thus effectively "vaporized", restoring solubility in aqueous base to the irradiated portions of the resist. Alternate resist systems based on this chemistry have also been reported (69,70). 

We have developed a novel silicone-based positive photoresist (SPP) for two-layer resist systems. SPP is composed of an acetylated poly(phenylsilsesquioxane)... 

Figure 11. Exposure curve of the acid-catalyzed resist system consisting of poly(4-hydroxystyrene), D2, and...

Interest in solution inhibition resist systems is not limited to photoresist technology. Systems that are sensitive to electron-beam irradiation have also been of active interest. While conventional positive photoresists may be used for e-beam applications (31,32), they exhibit poor sensitivity and alternatives are desirable. Bowden, et al, at AT T Bell Laboratories, developed a novel, novolac-poly(2-methyl-l-pentene sulfone) (PMPS) composite resist, NPR (Figure 9) (33,34). PMPS, which acts as a dissolution inhibitor for the novolac resin, undergoes spontaneous depolymerization upon irradiation (35). Subsequent vaporization facilitates aqueous base removal of the exposed regions. Resist systems based on this chemistry have also been reported by other workers (36,37). 

Poly(methyl methacrylate) (PMMA) is a classical one-component, positive resist system. PMMA is a single, homogeneous material that combines the properties of excellent film-forming characteristics, resistance to chemical etchants and intrinsic radiation sensitivity. 

Figure 42. A plot of proton beam vs electron beam sensitivity for several resist systems. COP is a copolymer of glycidyl methacrylate and ethyl acrylate, PVC is poly (vinylcinnamate), PCS is poly (chlorostyrene), PTBMA is polyO-butyl methacrylate), PVA is poly (vinyl acetate), PMMA is poly (methyl methacrylate). (Reproduced with permission from Ref. 57 J...

Negative DUV resist systems have also been developed, some of which have demonstrated extremely high sensitivity. These include poly (butyl a-chloroacrylate) (55) which is reported to be at least 500 times as sensitive as PMMA and partially chlorinated, narrow dispersity poly(p-vinyl toluene) (84), which has been imaged at 0mJ/cm in contact print-... 

Ito and coworkers (86-87) recently described a new DUV resist system that has high sensitivity, does not suffer swelling during development, and may be used either as a positive or negative system. The new resist is based on a formulation consisting of t-butyloxycarbonyl (t-BOC) protected poly(vinylphenol) 88 (Figure 50) and an onium salt sensitizer. Exposure... 

Other halogenated resist systems include partially chlorinated, narrow dispersity poly (vinyl-toluene). The latter differs from the CMS resist above in that chlorine is substituted on the main chain as well as on the pendant methyl group (44). 

We report here a novel technique used to measure the cross-linking and scission yields for negative acting resist systems. The three systems investigated were polyfglycidyl methacrylate-co-3-chlorostyrene) (GMC), poly(3-chloro-styrene) (PCLS), and polystyrene (PS). The technique requires generating an... 

Apart from multi-level layer resist systems, conventional positive-tone resists can be classified into two categories one-component and two-component systems. Classical examples of the former systems are polyfmethyl methacrylate), and poly (butene-1-sulfone) (2,3). Typical examples of the latter system are AZ-type photoresists, which are mixtures of cresol-formaldehyde-Novolak resins and a photoactive compound acting as a dissolution inhibitor... 

For further enhancement of electron beam sensitivity, the chlorinated Novolak resin was studied using poly (2-methyl-1-pentene sulfone) as a dissolution inhibitor. The chlorinated Novolak resin mixed well with the polysulfone, and there was no phase separation observed when the films were spin-coated. With 13 wt% of the polysulfone, the chlorinated Novolak resist cast from a cellosolve acetate solution yielded fully developed images with R/Ra = 9.2 after exposure to 2 / 2. It gave fully developed images with R/R0 = 3.2 at a dose of 1 / 2, as shown in Figure 3. There are some problems with this resist system some cracking of the developed resist images... 

Subsequently, a resist system was reported that is composed of polymers containing recurrent acid-labile pendant groups in combination with an ar-ylonium salt-acid photogenerator (64-67). An example of the type of polymer used in this work is poly(p-tert-butyloxycarbonyloxystyrene) (t-BOC-sty-rene). 

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