Growth of Ti-Based Interface Layer in Cu(Ti)/Glass Samples

Abstract

Cu(Ti) alloy films with low-resistivity and excellent-adhesion have been successfully prepared on glass substrates. To gain further resistivity reduction and adhesion strength, growth of a Ti-based interface layer was investigated using Rutherford backscattering spectrometry (RBS) in the present study. Cu(0$5 at%Ti) alloy films were deposited on glass substrates and subsequently annealed in vacuum at 400$600 C for 0:5$24 h. Results were compared with those for samples on SiO 2 substrate previously obtained. Ti peaks were obtained in RBS spectra only at the interfaces for both Cu(Ti)/glass and Cu(Ti)/SiO 2 samples. Molar amounts of Ti atoms segregated to the interfaces (n) were estimated from Ti peak areas. The m values estimated from the slopes of the log n versus log t lines were almost similar for all the samples (m ¼ 0:10$0:12), suggesting that growth of the Ti-based interface layers was controlled by a similar mechanism. The activation energy of the Cu(Ti)/glass samples was similar to that of the Cu(Ti)/SiO 2 samples, while a pre-exponential factor (Z) of the Cu(Ti)/glass samples was approximately half of the value of the Cu(Ti)/SiO 2 samples. The Z value shows the frequency with which the Ti atoms meet oxygen in the glass substrates. Impurities in the glass substrates lowered the frequency. These factors lead to the conclusion that growth rate of the Ti-based interface layers on glass substrates was slower than that on SiO 2 . The Ti-based interface layer growth was also influenced by microstructure of Cu(Ti) alloy films formed on the glass substrates. Columnar grains in the Cu(Ti) alloy films were seen to enhance Ti segregation. However, an equiaxed zone above the interface retarded Ti diffusion to the interface, leading to lack of Ti atoms for the reaction.