Pt/Ti/SiO₂/Si substrates

Abstract

Pt/Ti/SiO2/Si structures have been studied to investigate the structural, chemical, and microstructural changes that occur during annealing. Grain growth of the as-deposited Pt columns was observed after annealing at 650 °C, and extensive changes in the Pt microstructure were apparent following a 750 °C anneal for 20 min. In addition, two types of defects were identified on the surfaces of annealed substrates. Defect formation was retarded when the surface was covered with a ferroelectric film. Concurrent with the annealing-induced Pt microstructure changes, Ti from the adhesion layer between the Pt and the SiO2 migrated into the Pt layer and oxidized. It was shown with spectroscopic ellipsometry and Auger electron spectroscopy that for long annealing times, the titanium oxide layer can reach the Pt surface. Consequently, at the processing temperatures utilized in preparing many ferroelectric thin films, the substrate is not completely inert or immobile. The changes associated with Ti migration could be especially problematic in techniques that require the substrate to be heated prior to film deposition.

Stabilized Platinum Electrodes for Ferroelectric Film Deposition using Ti, Ta and Zr Adhesion Layers

“…The remaining thickness of TiO x under Pt is very thin (<10 nm), compared to 20 to 25 nm expected for complete oxidation of the Ti layer. The major part of the adhesion layer has hence out-diffused into the Pt grain boundaries or the PbTiO3, in agreement with previously reported results [6,8,[10][11][12]. Most probably, the remaining TiO 2 adhesion layer is porous, as is reported for the oxidation of bulk titanium [18].…”

“…Problems with diffusion and oxidation of Ti above and below Pt occur [6,[9][10][11][12]. TiO 2 -Pt metallisations have shown far superior stability [10].…”

Contributions to the dielectric losses of textured SrTiO3 thin films with Pt electrodes

“…3) showed that the density of threading dislocations (labeled "O" and "A" in Fig. 3) was in the order of 5¥10 SIMS showed that the Pt electrodes on the Ti adhesion layers contained Ti, consistent with findings by others [18][19][20]. The influence of Ti underneath (111) textured Pt electrodes on perovskite film texture is well documented [21,22].…”

Atomic structure of (111) SrTiO3∕Pt interfaces

“…Although it is well-known that Ti diffuses through Pt electrodes [18][19][20][21], the precise mechanisms by which Ti underlayers control perovskite thin film textures are not fully understood. In the literature, it has been suggested that either a Pt-Ti intermetallic or TiO 2 on the Pt surface provide a templating layer for (111) epitaxial perovskite growth [14,17].…”