| 초록 |
Various backbone structure polyimides were synthesized from dianhydrides (PMDA, BTDA, BPDA, 6FDA) and diamine(4,4?-ODA). For these four polyimide thin films which are generally used as microelectronic dielectrics, dielectric properties in 100% R.H. at 25 oC as a function of time were investigated by capacitance method using Film Dielectric Property Analyzer (FDPA). When the polyimide thin films were put into a water environment, the dielectric constants of all the polyimide films increase as the films absorbing water. The dielectric variation behavior from water sorption was well fitted to the Fickian model. Dielectric behaviors are quite different from each other, strongly depending upon the chemical and morphological structure. The kinetics of dielectric variation in polyimide thin films is closely related to the water diffusion kinetics and the amount of water uptake. The degree of dielectric variation by absorbing water varies from 0.49 to 1.01. The dielectric variation coefficients in films vary in the range of 1.25×10-10 cm2/sec to 6.01×10-10 cm2/sec. In addition, it is confirmed by gravity method using cahn microbalance that the degree of change in dielectric constants for the polyimide films by absorbing water is a nearly linear function of the amount of water uptake in spite of their difference of chemical structure.
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