A method of monitoring the synthesis of a PGO spin-coating precursor solution includes monitoring heating of the solution with a UV spectrometer and terminating the heating step when a solution property reaches a predetermined value. The method utilizes the starting materials of lead acetate trihydrate (Pb(OAc).sub.2.3H.sub.2 O) and germanium alkoxide (Ge(OR).sub.4 (R=C.sub.2 H.sub.5 and CH(CH.sub.3).sub.2)). The organic solvent is di(ethylene glycol)ethyl ether. The mixed solution of lead and di(ethylene glycol)ethyl ether is heated in an atmosphere of air at a temperature no greater than 190.degree. C., and preferably no greater than 185.degree. C. for a time period in a range of approximately eighty-five minutes. During the heating step the solution properties are monitored to determine when the reaction is complete and when decomposition of the desired product begins to take place. The solution is then added to germanium di(ethylene glycol)ethyl ether to make the PGO spin-coating solution. This second step also entails heating the solution to a temperature no greater than 190.degree. C. for a time period in a range of 0.5 to 2.0 hours. This heating step is also monitored with a UV spectrometer to determine when the heating step should be terminated. The process results in a PGO precursor solution suitable for use in spin-coating.
This application is a Continuation-in-Part of U.S. application Ser. No. 09/822,637 filed on Mar. 30, 2001, entitled METHOD OF THE SYNTHESIS AND CONTROL OF PGO SPIN-COATING PRECURSOR SOLUTIONS now U.S. Pat. No. 6,537,361.
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.
A method of forming a ferroelectric thin film on a high-k layer includes preparing a silicon substrate; forming a high-k layer on the substrate; depositing a seed layer of ferroelectric material at a relatively high temperature on the high-k layer; depositing a top layer of ferroelectric material on the seed layer at a relatively low temperature; and annealing the substrate, the high-k layer and the ferroelectric layers to form a ferroelectric thin film.
