Effects of thermal treatment on porous amorphous fluoropolymer film with a low dielectric constant

Amorphous fluoropolymer (AF) thin films have been prepared from Teflon AF 1600 solution by spin-coating. Scanning electron micrograph (SEM) observations reveal that the film has planar and compact surface without any pinhole, and there are many pores in the matrix. By capacitance–voltage (C–V) and current–voltage (I–V) measurements, the dielectric constant of the AF film is equal to 1.57 at 1 MHz, and breakdown strength is 2.07 MV cm−1. The Fourier transform infrared spectroscopy (FTIR) spectra and X-ray diffraction (XRD) patterns of the films show that the films have excellent thermal stability below 400°C, and thermal treatment does not change amorphous nature of the films. X-ray photoelectron spectroscopy (XPS) spectra reveal decomposition of CF3 groups due to annealing at 400°C, leading to a remarkable increase in CF2 groups. Possible decomposition mechanisms of AF film are also discussed.