| 摘要 |
In humid atmospheres (e.g., 55% relative humidity or above) solutions of 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride/2,2-bis [4-(aminophenoxy)phenyl]hexafluoropropane polyamic acid polymers tend to be unstable in the sense that during spin coating operations undesirable precipitate formation may occur on the rotating surface of a semiconductor wafer. The result is the formation of unacceptable coatings due to their irregularity and lack of uniformity. Described are solutions of these polyamic acid polymers in a solvent containing at least 40% by weight of one or more liquid aromatic hydrocarbons having a boiling point of at least about 110 DEG C. and at least 5% by weight of one or more dipolar aprotic solvents having a boiling point of at least about 150 DEG C., such that the solution (a) contains on a weight basis from about 5% to about 40% of the polyamic acid and (b) does not undergo precipitate formation during spin coating in an atmosphere of up to at least about 55% relative humidity.
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