| abstract |
A liquid form adhesive system is provided for spin-coating on wafers and mounting to rigid carrier substrates to support thinning and backside processing. The liquid adhesive comprises about 30-35% of a rosin, between 5-10% of a thermoplastic urethane, a nonionic surfactant present between 1-3%, and a trace of an ultraviolet fluorescing dye. The entire system is dissolved in 50-65%, by weight, of a dual solvent mixture composed of dimethylacetamide and propylene glycol monomethyl ether. When the mixture is made to a specific viscosity, filtered, applied by a spin-coating method to the wafer frontside surface, and cured, the result is a uniform and smooth surface of defined thickness. When the coated wafer is mounted to a rigid substrate, it may be mechanically thinned to thicknesses down to and beyond 25 um, depending upon the wafer composition, diameter, and process. Once thinned, the adhesive is safe for backside processing and is dissolved away at completion to provide a thinned wafer that is clean and ready for final dicing or chipping operations. |