Processing of Polyimide Using Supercritical Carbon Dioxide

Abstract

The technique of the deposition of polyimide inside the micro-scale spaces was developed using supercritical carbon dioxide (scCO₂). The present paper explains solubilities of polyimide monomers in scCO₂, phase behaviors during the polymerization of monomers to polyamic acid in scCO₂, and the deposition of polyimide inside the micro-scale trenches on the silicon wafer. As for the monomers of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride, the trenches were filled with the polymers at relatively low deposition temperature. On the other hand, the trenches were filled with polyimide that consisted of fluorinated monomers of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl and 4,4'

(hexafluoroisopropylidene)diphthalic anhydride even at high deposition temperature.