Bisazide-rubber resists

Bisazide produces binitrene by irradiation. 2,6-Dibenzylidene-4-methylcyclohexanone-p,p -bisazide (DMC-bisazide) (Figure 1.12) is introduced into the rubber resist, cis-l,4-polyisoprene. The rubber resist is crosslinked by DMC-bisazide as Equation (1.114) ... 

Unlike classic solvent-developed negative resists such as cychzed rubber/ bisazide resist, which swell during development, the positive DNQ/novolac resists do not appreciably swell during their development in aqueous alkaline solutions. It should be emphasized that the dissolution of novolac is not exactly the same as that of the usual case II mass transfer kinetics in that it is not physical relaxation of the polymer molecules that is rate controlling. In case II dissolution, the rate-determining events occur at the polymer-gel interface. ... 

Photo-crosslinking of negative resists is exemplified by the bisazide-cyclized rubber system widely used in the production of offset printing plates. The system hardens when exposed to actinic rays. 

Thus, when cyclized rubber-bisazide system is exposed to actinic rays, bis nitrenes are formed which cross-link via double bonds of the cyclized rubber to insoluble products (Figure 4). The system is therefore negative resists. 

Introducing DMS-bisazide into cyclized rubber gives a superior negative resist. The bisazide produces crosslinking between cyclized rubber molecules by reaction of binitrene, similarly to Equation (1.114). A variety of bisa-zides are reported for crosslinking of rubber. They are shown in Figure 1.14. 4,4 -Diazide benzophenone is one of the basic types of diazides. 4,4 -Diazide benzalacetone is familiar with polyisoprene rubber. 2,6-Dibenzylidene cyclohexanone p,p -bisazide is almost the same as DMS-bisazide. 

Bisazide resists provide strong resistivity for chemicals because of the rubber. However, resolution of imaging is limited. Bisazide resists were used for production of IC in the early stages. Organic solvents are used for... 

Negative photoresist chemistry. A. Cross-linking of a prolyisoprene rubber by a photoreactive bisazide. B. A radical induced polymerization and cross-linking of an acrylate monomer. C. A single component resist. Electron beam irradiation produces anions that launch a cascade of epoxide ring-opening reactions to cross-link the poljrmer. 

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