Positive photoresists, composition

Crosslinked positive photoresist compositions, (V), were prepared by Ogata et al. (5), which exhibited a significant change in alkali solubility prior to exposure and formed fine patterns with a high level of resolution. 

Okui, T. Misumi, K. Chemically amplified positive photoresist composition for thick-film photoresist laminate and manufacture of thick-fihn resist pattern and connection terminal. U.S. Pat. Appl. Publ. US 2006141389, 2006 Chem. Abstr. 2006,145, 113370. 

The sulfonic acid moiety has been iacorporated iato a variety of nonfluofinated polymeric materials (111). Chain-end sulfonated polymers are produced by the reaction of sultones with polymeric organolithiums (112). Polymeric sulfonic acids such as these are iacorporated ia positive-working photoresist compositions (113). 

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). 

At the present time, most of the positive photoresists used in the manufacture of microcircuits consist of a low molecular weight phenolic resin and a photoactive dissolution inhibitor. This composite system is not readily soluble in aqueous base but becomes so upon irradiation with ultraviolet light. When this resist is exposed, the dissolution inhibitor, a diazoketone, undergoes a Wolff rearrangement followed by reaction with ambient water to produce a substituted indene carboxylic acid. This photoinduced transformation of the photoactive compound from a hydrophobic molecule to a hydrophillic carboxylic acid allows the resin to be rapidly dissolved by the developer. (L2,3)... 

A new family of perfluoroacrylate and methacrylate based positive and negative tone photoresist compositions activated at 193 run has been prepared by free radical homo-or co-polymerization of acrylate or methacrylate derivatives. Polymeric agents prepared in this manner had Mn s between 5,000 and 50,000 daltons and were readily soluble in organic solvents. 

Knowledge that silyl substituents may be incorporated into standard resist chemistry to effect etching resistance has prompted several workers to evaluate silylated novolacs as matrix resins for conventional positive-photoresist formulations. Typically, these resists operate via a dissolution inhibition mechanism whereby the matrix material is rendered insoluble in aqueous base through addition of a diazonaphthoquinone. Irradiation of the composite induces a Wolff rearrangement to yield an indenecarboxylic acid (Figure 4), which allows dissolution of the exposed areas in an aqueous-base developer (35). 

Novel o-quinone diazides have been the subject of several patents for applications as positive photoresists or in lithography. Thin-film composite membranes with pendant diazoketone groups have been synthesized. The resulting membranes can be modified photochemically after fabrication. 

Chemical nature of photoresists, the chemistries involved in the photolithography, the properties of photoresists are briefly described. The discussion includes diazonaphthoquinone/novolac positive photoresists, polymer-aromatic diazide negative photoresists, photopolymerizable compositions, chalcogenide glass using systems, chemically amplified photoresists, and photoresists with an image formation in a thin layer. 

The Py-GC procedures and equipment are applicable to the ultimate analysis of polymers, and also to the analysis of copolymers if the ultimate composition of the monomers is different. Meade et al. [246] determined the oxygen content of organic compounds with the use of a carbon catalyst at 1050°C. Under these conditions, methane, hydrogen and carbon monoxide are formed and were separated on a column with molecular sieves. The application of Py—GC to determine the oxygen content of polymers has been described [247,248], and also the nitrogen content of positive photoresists [249]. 

Kawabe, Y Kokubo, T. Positive-working photoresist composition. Eur. Pat. Appl. EP 385442, 1990 Chem. Abstr. 1991,114, 237657. 

Nunomura, M. Hashimoto, M. Kasuya, K. Sasaki, M. Positive-working photoresist composition and patterning method using same. Jpn. Kokai Tokkyo Koho JP 05173327, 1993 Chem. Abstr. 1994,121, 46621. 

Kawabe, Y. Uenishi, K. Kokubo, T. Positive-working photoresist compositions providing high resolution pattern. Jpn. Kokai Tokkyo Koho JP 04296754, 1992 Chem. Abstr. 1993,118, 222918. 

Roorensu, F. Improved development and developer solution for positive-working photoresist composition. Jpn. Kokai Tokkyo Koho JP 63131137, 1988 Chem. Abstr. 1989, 110, 163602. 

Resists are comprised of several components. The classic composition of negative photoresist is an azide sensitized rubber such as a polyisoprene polymer base with a bis-aryldiazide sensitizer, and a carrier solvent that makes the resist a liquid, allowing it to be spun on the wafer as a thin layer (sometimes additives are included such as dyes to control the light rays). A typical positive photoresist would be aphenol-formaldahyde Novolak resin structure and a diazonaphthoquinone sensitizer in a carrier solvent. 

NQD-novolak type positive photoresists have been widely used in the field of high resolution optical microlithography for years. An example of the resist composition is shown in Figure 1. Esters of polyhydroxybenzophenone and 1,2-naphthoquinone diazidc-5-sulfonic acid are commonly used as a photoactive compound (PAC). 

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