Quantitative XPS determination of Pt coverage on SrBi2Ta2O9 thin films for ferroelectric memories

Abstract

AbstractX‐ray photoelectron spectroscopy measurements were conducted for a spin‐coated SrBi2Ta2O9 (SBT) system with sputter‐deposited 5 nm thick Pt film on it. The spectral peaks were analysed quantitatively under several surface structure models. The XPS results also were compared with SEM observation results. The Pt coverage was lowest (∼15%) on a specimen prepared from complexed alkoxide solution followed by a second annealing at 800 °C in O2 and sintering in a hydrogen atmosphere at 400 °C (H2 sintering), whereas it was highest (97%) on a specimen prepared from a sol–gel solution without any other treatment except crystallization. From regression analysis of all the data, the effects of the solution property, second annealing and H2 sintering on Pt coverage were evaluated. It was found that the effect of the second annealing in O2 was very large, whereas that of the H2 sintering does not give a large effect but it certainly causes a decrease in the apparent Pt coverage. Even the difference in solution for spin‐coating has an influence on the Pt coverage, i.e. sol–gel and complex solutions give the highest and lowest values, respectively. It was clarified that the Pt‐coverage had a clear correlation with fabrication factors, such as solution property, second annealing in O2 and H2 sintering. There was an excellent agreement between XPS and SEM results. Copyright © 2001 John Wiley & Sons, Ltd.