Accurate and rapid determination of thickness, n and k spectra. and resistivity of ITO films

摘要

The transparent conductor, indium tin oxide (ITO), is an important thin film component of flat panel displays. An optimum ITO film should be both highly transparent to visible wavelengths and at the same time, conductive. In practice, however, atrade-off exists between these two attributes, making it difficult to produce a film that simultaneously meets both demands. In order to achieve the optimum balance between these properties, an effective method of characterizing ITO films is necessary. In this talk we will present results of a new measurement technique that simultaneously determines, thickness, the spectra of the refractive index (n) and extinction coefficient (k) from 190 to 1100 nm, and the energy band gap, of ITO films deposited oneither transparent or opaque substrates. In addition, we will demonstrate how the film's resistivity can be correlated to the film's extinction coefficient. This technique is based on wide-band spectro-photometry, combined with spectral analysis thatincorporates the Forouhi-Bloomer dispersion equations for n and k [1,2]. The measurement technique is non-destructive and takes 1-2 seconds.