Physical characterization of hafnium oxide thin films and their application as gas sensing devices

Abstract

Thin films of hafnium oxide have been prepared by using a dual ion beam sputtering system. A study of their physical properties is reported. In particular, structural and compositional characterization was performed by means of x-ray diffraction and x-ray photoelectron spectroscopy techniques, showing a mixture of amorphous and polycrystalline structure and a substoichiometric composition. The atomic force microscopy results have shown a crater-like morphology probably due to the deposition process. In addition the gas sensing characteristics were analyzed in the presence of carbon monoxide. The variations in the electrical resistance have shown the capability of the films to detect CO and then the possibility to use hafnium oxides as a new sensitive material in the field of gas sensors.

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

“…In particular, the high refractive index, 2 atomic/mass density, 18 and mechanical properties 92,93 of HfO 2 have made it a favorable choice as a protective and wear-resistant film in complex optical interference and reflective coatings, 30,94,95 and as a pore sealant, 96 selectively grown hard-mask, 97 and Cu diffusion barrier 36 in lowdielectric-constant (low-k) metal interconnects. The unique defect and surface chemistry of HfO 2 has further led to its use as a solid-state electrolyte in valence change resistive switching devices, 9,10 catalytic surface material in gas sensors, 98 and even garnered some interest as an antibacterial coating in bioNEMS applications. 99 Lastly, the recently discovered ferroelectric properties 100,101 of HfO 2 have also led to renewed interest in ferroelectric based memory 102 and the development of new negative capacitance devices.…”

“…Electrical and optical properties.- Table II 18,190,191 AlN (RI = 1.8-2.2, k = 5.7-9.5), 84,86,88,[97][98][99][100][101] and BeO films (RI = 1.67-1.72, k = 6.5-6.8). 184,192 Relative to SiO 2 , all the investigated dielectrics have substantially higher values of RI and k. Relative to SiN:H, however, only HfO 2 has a significantly higher RI and k.…”

Deposition of HfO2 Films by Liquid Injection MOCVD Using a New Monomeric Alkoxide Precursor, [Hf(dmop)4]

“…M.p. 38-40 C. 1 [Hf(dmop) 4 ]: 50ml of 0.758M solution of dmopH (0.0375 moles) in anhydrous hexane was slowly added to a solution of Hf(NMe 2 ) 4 in anhydrous hexane kept at 0 C. Once the addition was complete the reaction mixture was stirred for 6 h at room temperature. All volatiles were removed in-vacuo.…”

“…[1,8] MOCVD is an attractive technique for the deposition of HfO 2 , [9] offering the potential for large area growth, good composition control and film uniformity, and excellent conformal step coverage on nonplanar device geometries. An essential requirement for a successful MOCVD process is the availability of precursors with the appropriate physical properties and decomposition characteristics.…”

“…Hafnium dioxide (HfO 2 ) has a number of important potential applications in gas sensing devices, [1] tunnel junctions, [2] optical coatings, [3] and thin film capacitors. [4] HfO 2 has a high permittivity (k), and is relatively stable in contact with silicon making it a promising material to replace SiO 2 as the gate dielectric insulating layer in sub-0.1 lm complementary metal-oxide-semiconductor (CMOS) devices.…”