Low Temperature Radio-Frequency-Sputtered (Ba, Sr)TiO[sub 3] Films on Pt/TiN/Ti/Si Substrates with Various Oxygen/Argon Mixing Ratios

Abstract

Ba,Sr)TiO 3 ͑BST͒ films were fabricated on Pt/TiN/Ti/Si substrates by low temperature radio frequency magnetron cosputtering at 300°C. Material and electrical properties of BST films sputtered at low temperatures are significantly affected by the O 2 /(Ar ϩ O 2 ) mixing ratio ͑OMR͒. Plasma emission spectra indicate that the deposition rate declines at a higher OMR due to oxide formation on the target surface. The dielectric constant of the BST films can reach a maximum of 364 at 5% OMR. The ten-year lifetime of the time-dependent dielectric breakdown implies that the reliability of the capacitor can be enhanced at a higher OMR due to compensation of oxygen vacancies and smaller grain sizes. Current-voltage analysis indicates that the leakage current of the Pt/BST/Pt capacitor is limited by Schottky emission ͑SE͒/Poole-Frenkel emission ͑PF͒ at a lower/higher applied field. The applied field boundary between SE and PF shifts toward higher field as OMR increases. Moreover, an energy band model was proposed and this leakage mechanism was discussed.

Properties of MgTiO3 thin films prepared by RF magnetron sputtering for microwave application

“…5 shows the surface morphology of the films deposited at a substrate temperature of 400 1C sputtered for 3 h at an RF power of 400 W with various Ar/O 2 ratios. The Rms roughness varied from 7.87 to 4.84 nm as the O 2 concentration as increased from 0% to 30%; other work has revealed a similar trend [15]. For various Ar/O 2 ratios of the mixed sputtering gas, a 0% oxygen concentration produced a film with a denser structure and better crystallinity than any other oxygen concentration , as shown in Fig.…”

Improvement of Electrical Properties of $\hbox{Ba}_{{\bf 0.7}}\hbox{Sr}_{\bf 0.3}\hbox{TiO}_{\bf 3}$ Capacitors With an Inserted Nano-Cr Interlayer

“…Lower values of PF boundary are obtained for BST specimens containing Cr interlayer (t Cr = 2 nm and t Cr = 5 nm). Our previous work [1] suggests the more oxygen vacancies and the higher interfacial space charge concentration, the smaller is the electric field boundary of SE/PF. It is suggested these defect appeared between Ba x Sr 1−x TiO 3 and TiO 2 .…”

“…The PF transport mechanism is a result of the lowering of the barrier height of traps in the dielectrics. The conduction mechanisms of metal/BST/metal capacitors are usually interpreted as SE at lower electric fields and PF emission at higher fields [1]. The dynamic relative dielectric constant can be inferred from n 2 , where n is the refractive index.…”

“…In order to keep the storage capacitance, Ba x Sr 1−x TiO 3 dielectrics are extensively investigated for applications in the high-density dynamic random access memories (DRAM) and the capacitors of the analog/mixed circuit. The high charge storage density, the low leakage current, high breakdown field, and high time-dependent dielectric breakdown (TDDB) [1]- [3] of BST are attractive for use in DRAM and the analog/mixed-signal circuit. However, the stability of the BST dielectric constant becomes a major concern while the applied voltage and/or operating temperature vary.…”

Microstructural and optical properties tuning of BiFeO3 thin films elaborated by magnetron sputtering

“…We have noted a sharp decrease in the deposition rate when the oxygen percentage increases. The decrease of the deposition rate as function of oxygen-argon is already observed on BST thins films [35,36]. This decrease can be explained by low the proportion of argon ions in the plasma or by the modification of the target surface in the presence of oxygen or both phenomena at the same time.…”