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Thick resist coating technique for slider air bearing surface etching applications Disclosure Number: IPCOM000131031D
Publication Date: 2005-Nov-04
Document File: 2 page(s) / 32K

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A short spin technique was developed to produce crack-free, thick film photoresist coatings for use in producing slider air bearing patterns. This technique allows the usage of resists in the 15 micrometer thickness regime that were normally developed for 4-6 micrometer application. Thus low glass transition photoresists can be utilized that do not develop form cracks during processing.

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Thick resist coating technique for slider air bearing surface etching applications

       Disclosed is a method for coating photodefinable films on substrates for use in creating slider air-bearing patterns. Often air-bearing patterning requires thick positive photoresist films of 15 micrometers or more to serve as masks during relatively deep etch steps. From the product development standpoint, this process is very desirable since it affords air-bearing patterns that are both fence-free and have the shallow etch wall profiles that afford good lift characteristics and extendibility to future product designs. There are several photoresist manufacturers who produce high viscosity formulations required to coat 15 micrometer thick films by standard spin coating techniques. However when these candidates were evaluated by coating on row-bar carriers and baking to remove solvent, resist film cracking was observed which gave rise to ledge defects and unacceptably high yield loss.

     Photoresist film cracking can be mitigated by use of resists that have lower glass transition temperatures or are formulated in solvents such as propylene glycol methyl ether acetate (PGMEA) that remain in the film after baking and cause plasticization. One such resist is AZ9260 produced by AZ Electronic Materials. This resist however is not available in a viscosity range that allows coating of 15 micrometer thick films by conventional spin coating techniques. As a solution to this problem we have discovered that the row-bar carriers can be spin coated using specially developed techniques that allow usage of lower viscosity photoresists. These techniques, described in detail below, have the capability of providing 15 micron thick films using photoresists whose viscosity would normally limit film thickness to six microns or less. This discovery has enabled us to use commercial photoresists that are not prone to film cracking, such as AZ9260. Furthermore by lowering the AZ9260 bake temperature, more PGMEA can be retained in the film, which further lowers the glass transition temperature and prevents resist film cracking.

     Normally spin coating operations are carried out using procedures where the substrat...