Preparation of hafnium oxide thin films by sol–gel method

Abstract

Hafnium oxide (HfO 2 ) films were grown on SiO 2 /Si substrates by a sol-gel method, and their crystalline structure, microstructure and electrical properties were investigated. X-ray diffraction analysis indicated that the monoclinic HfO 2 films could be obtained by annealing at 500°C. A transmission electron microscopy (TEM) image showed that the films were grown as a spherulite grain structure with a mean grain size of approximately 15 nm. The dielectric constant of the HfO 2 films of 300 nm was approximately 21.6, and the current-voltage measurements showed that the leakage current density of the HfO 2 films was approximately 1.14×10 −5 A/cm 2 at an applied electric field of 100 kV/cm. The sol-gel method-fabricated HfO 2 films are concluded to be feasible for MEMS applications, such as capacitive-type MEMS switches.

Organic–inorganic hybrid thin films based in HfO2 nanoparticles as dielectric for flexible electronics

“…Figure 7 also shows how pure PVP has a low k while increasing the nanoparticles embedded into the polymer matrix results in an increase to a high k. The dielectric property of material with nanoparticles depends on their ratio content of hafnium. The k value for our hybrid films is close to the HfO 2 reported by physical and chemical methods around 21 to 23 [4,14]; however, further studies are necessary to reach its maximum dielectric constant of the hafnium oxide. Figure 8 shows the leakage current density (J) as a function of the applied electric field (E) for our film that presented the highest k value (hybrid 2).…”

“…In ref. 4, the authors reported the use of sol-gel process for obtaining HfO 2 thin films with high k = 21.6, but the processing required an annealing at 750°C. For flexible electronics using plastic substrates, solution processable gate dielectrics are preferred because they are easily formed using low-temperature processing, large area applications, compatibility with light weight, and mechanically flexible.…”

“…Lee et al [9] also studied a hybrid gate dielectric solution synthesized by sol-gel reactions between 3-methacryloxypropyltrimethoxysilane (Aldrich), and zirconium isopropoxide [Zr(OPr i )] 4 . The maximum temperature was 170°C with k = 6.3.…”

High‐Mobility ZnO Thin Film Transistors Based on Solution‐processed Hafnium Oxide Gate Dielectrics

“…HfO 2 thin films can be grown using a wide range of vacuum based deposition techniques namely the atomic layer deposition (ALD), chemical vapor deposition (CVD), magnetron sputtering, pulsed laser deposition (PLD) and molecular beam epitaxy (MBE) . HfO 2 films deposition from solutions have also been reported . However the preferred industrial scale methods are CVD and ALD.…”

Solution-processed hafnium oxide dielectric thin films for thin-film transistors applications

“…Compared with organic and polymer dielectric materials, the inorganic dielectrics such as aluminum oxide (AlO x ) [1,2], zirconium oxide (ZrO x ) [3][4][5], yttrium oxide (YO x ) [6][7][8], and hafnium oxide (HfO x ) [9][10][11], are proved to be more suitable for low-operating voltage thin-film transistors (TFTs) because of their large conduction band offset and excellent solvent resistance. Among these high-k dielectrics, HfO x is considered as the most promising candidate due to its high dielectric constant (k~25-30) and wide band gap (5.68 eV) with a large conduction band (CB) offset of 1.4 eV [12,13]. The CB offset is one of the key criteria in the selection of a gate dielectric.…”