RF Magnetron Sputtering Process for (Ba,Sr)TiO₃ Thin Films with Higher Dielectric Constant

Abstract

Ba,Sr)TiO 3 (BST) films were deposited by RF magnetron sputtering using BST sintered ceramic targets and an approach to deposit BST films with higher permittivity by sputtering deposition was explored aiming to the application of thin film capacitor, RF tunable components and so on.Basic sputtering conditions such as RF power, deposition temperature and so on were varied in this study. BST films and Pt/BST/Pt capacitors were investigated by electrical properties, XRD analysis and SEM observation. It became clear that deposition temperature, deposition rate, and BST film thickness were important parameters for optimization of the dielectric constant. From the non-linearly relationship between dielectric constant and BST film thickness, we could also find that the interfacial layer between BST and Pt bottom electrode was important for controlling the BST film properties. Furthermore, an approach to enhance the crystalline quality has to be explored for further improvement of BST film properties. Dielectric constant could be raised up to 10% by just changing the gas flow sequence of BST sputtering process.

Microwave Properties of Parallel Plate Capacitors based on (Ba,Sr)TiO3 Thin Films Grown on SiO2/Al2O3 Substrates

“…From all BST XRD peaks, the most intense was (110) with 2θ value at 31.75 o , while the (111) peak at 39.2 o is overlapped with the Pt(111) peak. It is seen that (110) reflection has higher intensity for BST grown at higher temperatures [20]. Based on the analysis of experimental data, all samples (including the CSD ones [19]) show almost identical diffraction patterns and are attributed to cubic (perovskite) crystal symmetry.…”

“…Further details have been provided in ref. [9] and [20]. After formation of the BST films by both deposition techniques the samples were deposited with 200nm top Pt electrodes.…”

Characterization of Thin-Film Decoupling and High-Frequency (Ba,Sr)TiO3 Capacitors on Al2O3 Ceramic Substrates

“…Details on the sputtering deposition conditions were provided previously. 11) After the formation of the BST films by both deposition techniques, the samples were deposited with top Pt electrodes. Ar ion milling was employed to pattern the Pt/BST/Pt stack.…”

“…BST film morphologies and phase analyses were reported previously. 8,10,11) After the ion milling, the capacitor structures were encapsulated using a low-k interlayer dielectric (ILD). Vias were formed in the ILD by standard photolithography and reactive ion etching (RIE), followed by the deposition and patterning of a standard metal interconnect layer.…”

Thin-Film Process Technology for Ferroelectric Application

“…If BST capacitor is assumed to be a simple series connected capacitor between transition layer near BST/Pt bottom electrode interface and main layer which represents BST film excluding transition layer, it is speculated that there have been the transition layer in this BST film. [21] As a simple experiment, effects of gas flow sequence for BST deposition was investigated. Gas flow sequence, that is ON/OFF step was changed, while Ar/O 2 flow ratio was not changed.…”