Diazo resin

Overlay Proofing. Overlay proofing systems can be categorized as wet- or dry-processed systems. The negative working wet-processed systems are generally composed of polymeric diazo resin salts (haUdes or heavy metal), which after photolysis form an insoluble adduct. 

Sun et al. extended the diazo-carboxylate covalent bonding to the assembly between diazo-resins and gold nanoparticles.19 The ionic LbL assembly was first achieved by using diazo resins (DAR) and citrate-capped gold nanoparticles. Under UV irradiation, diazonium groups decomposed to phenyl cations that reacted with the nucleophilic carboxylate groups on the gold nanoparticles via an SN1 reaction. 

Sun J, Wu T, Sun J, et al. (1998) Fabrication of covalently attached multilayer via photolysis of layer-by-layer self-assembled films containing diazo-resins. Chem Commun 17 1853-1855... 

Commercial presensitized plates are formulated on two chief groups of photoresponsive compounds, namely, (1) diazo resins and diazo oxides, and (2) cinnamate resins, some of which have been... 

Sun, J.Q. Wu, T. Liu, F. Wang, Z.Q. Zhang, X. Shen, J.C. (2000). Covalently Attached Multilayer Assembhes by Sequential Adsorption of Polycationic Diazo-Resins and Polyanionic Poly(aayhc add). Langmuir, 16,4620-4624. 

This method is suited to large amounts of crosslinking and low swelling polymer gels. Examples are known of water soluble polymers, such as poly(vinyl alcohol) and poly(N-vinyl pyrrolidine), being photocrosslinked via diazo resins, bisazides, chromic acid, and photodimerization of polymers having photosensitivity, such as styrenebazolium salt, on the water soluble polymer main chain. 

A more workable photopolymer system was based on the chemistry of diazonium salts. The diazo salt or diazo resin can be coated from water along with a water soluble binder, such as poly (vinyl alcohol). Upon exposure the salt is photolyzed, probably forming a phenol or haloaro-matic. The neutral organic photoproducts dissolve much more slowly than do the ionic starting materials. 

The group of Janda has presented a microwave-mediated oxazole synthesis utilizing /3-ketoestcrs bound to a novel polymeric resin [57]. The desired polymer support was prepared by transesterification reactions of tert-butyl /f-ketoesters and hydroxy-butyl-functionalized JandaJel resin and subsequent standard diazo transfer. The resulting a-diazo /f-ketoesters were employed for the synthesis of an array of oxa-zoles (Scheme 7.41). 

One such process involves the thermal decomposition of a diazo compound to give an acid that cross-links phenol formaldehyde resins upon heating, similar to the conventional UV initiated plates used in the industry (Figure 4.3), but other sensitisation methods are also used (see section 4.5). It is also possible to produce plates in a dry resin process by ablation or phase change methods. 

The most popular positive resists are referred to as DQN, corresponding to then-photoactive compound (DQ) and base material (N), respectively. DQ stands for diazo-quinone, and N stands for novolac resin. The repeat unit of a novolac resin is shown in Figure 7.47. Novolacs normally dissolve in aqueous solutions, but combinations of... 

Several attempts have been made to redesign the traditional two-component near-UV positive resist systems to make them compatible with the deep-UV. Recall that the major problems associated with deep-UV exposure of conventional resists are related to non-bleaching of the o-quinonediazide sensitizer on exposure because of photoproduct absorbance, and strong absorption of the novolac resin. Willson and coworkers34 attempted to solve this problem using dissolution inhibitors based on 5-diazo Meldrums acid, which undergoes photochemical decomposition as follows ... 

Development of Resist Patterns. Development was done in AZ2401 developer diluted with 2 to 5 times its volume of water AZ2401 is an aqueous solution of KOH with a surfactant. When the resist films were exposed to electron beam doses of 5 iC/cm2 at 25 keV, it usually took 1.5 to 2.0 min for complete development of the images using a diazo-naphthoquinone sensitizer with o-chloro-cresol-formaldehyde Novolak resin in (1 3) AZ2401/water developer. With poly(2-methyl-l-pentene sulfone) the chlorinated Novolak resin exposed to I juC/cm2, it took 2.0 min in (1 4) AZ2401 developer for complete image development. 

Figure 2. SEM pictures of a composite resist made of a diazo-naphthoquinone sensitizer and o-chloro-m-cresol-formaldehyde Novolak resin after various doses (a) 7 , (b) 5 . 2, (c) 5 " 2...

Although the Novolak resin of the w-cresol-benzaldehyde failed to show a marked increase in CF4 plasma etching resistance, the Novolak resins of hydroxy-naphthalene-hydroxybenzaldehyde showed a remarkable increase in the plasma etching resistance. The resist films also yielded excellent patterns when used together with a diazo-naphthoquinone sensitizer almost non-diluted AZ2401 developer had to be used for image development due to the hydrophobic nature of the naphthalene group. 

One approach to following reaction kinetics on a solid phase is as follows. A trace amount of resin beads is taken out of a reaction vessel, rinsed briefly with solvent, and subjected to single-bead FTIR analysis or analysis by FTIR with a beam condenser. As an example, the kinetics of the reaction shown in reaction 1 was studied,4 that is, a combination of Wang resin 1 with succinimidyl 6-(iV-(7-nitrobenz-2-oxa-l,3-diazo-4-yl)amino)hex-anoate 2 to produce compound 3. The IR spectra for this transformation are... 

Because of the special structural requirements of the resin-bound substrate, this type of cleavage reaction lacks general applicability. Some of the few examples that have been reported are listed in Table 3.19. Lactones have also been obtained by acid-catalyzed lactonization of resin-bound 4-hydroxy or 3-oxiranyl carboxylic acids [399]. Treatment of polystyrene-bound cyclic acetals with Jones reagent also leads to the release of lactones into solution (Entry 5, Table 3.19). Resin-bound benzylic aryl or alkyl carbonates have been converted into esters by treatment with acyl halides and Lewis acids (Entry 6, Table 3.19). Similarly, alcohols bound to insoluble supports as benzyl ethers can be cleaved from the support and simultaneously converted into esters by treatment with acyl halides [400]. Esters have also been prepared by treatment of carboxylic acids with an excess of polystyrene-bound triazenes here, diazo-nium salts are released into solution, which serve to O-alkylate the acid (Entry 7, Table 3.19). This strategy can also be used to prepare sulfonates [401]. 

A photoresist pattern was deposited on a nonlinear diazo dye film and then oxygen etched to form a line of nonlinear and linear sections with a 32 pm QPM period. The upper surface was then planarized with a UV cured resin. A raised QPM +/0 channel waveguide was then formed with three more processing steps [104]. Despite the complexity of the fabrication, losses were below 3 dB cm 1 at 1.59 pm and a maximum SHG figure of merit of 4x10 % W 1 cm 2 was obtained [105,106]. 

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