Structural and Electrical Characteristics of High-k Sm[sub 2]TiO[sub 5] Gate Dielectrics

Abstract

A high-k Sm 2 TiO 5 gate dielectric was grown on silicon substrate through reactive cosputtering. We found that the Sm 2 TiO 5 dielectrics annealed at 800°C exhibited excellent electrical properties such as high capacitance value, almost no hysteresis voltage, small frequency dispersion, and low leakage current. This phenomenon is attributed to a rather well-crystallized Sm 2 TiO 5 structure and composition observed by X-ray diffraction and Auger electron spectroscopy, respectively.High-dielectric-constant ͑high-k͒ materials are used as gate dielectrics replacing SiON films because the downscaling of Si-based field effect transistors for complementary metal oxide semiconductor devices has reached a limitation in thickness of SiON dielectrics. 1 Rare-earth ͑RE͒ metal oxides, such as , 5 attracted a lot of attention and showed many promising properties. As a candidate material, it should have high permittivities, large bandgaps, large conduction band offsets, and thermodynamic stability with Si. 6,7 Dakhel investigated the optical and dielectric properties of amorphous monoclinic phase Sm 2 O 3 thin films. 7 However, many low-permittivity RE films were reported. 8-10 The low permittivity is mainly attributed to the low density of amorphous RE films or the moisture absorption, resulting in the formation of low-permittivity hydroxide after exposure to an air ambient. 11 The moisture absorption of La 2 O 3 films is partly attributed to the oxygen vacancies in the films. 12 The incorporation of TiO 2 film into RE metal oxide has proven to be stable against moisture. 13 In addition, van Dover 14 showed that the TiO 2 or Ti combined with RE metal oxide films has attracted considerable attention as a method to achieve a high-k dielectric material with excellent electrical properties in terms of a large dielectric constant, high breakdown voltage, and low leakage current. In this article we explored high-k Sm 2 TiO 5 dielectrics deposited on Si substrate by reactive cosputtering. The film structure and composition were investigated combining X-ray diffraction ͑XRD͒ and Auger electron spectroscopy ͑AES͒. Furthermore, the effects of annealing on the electrical properties are discussed. ExperimentalMetal-oxide-semiconductor ͑MOS͒ devices incorporating Sm 2 TiO 5 dielectric films were deposited on 4 in. p-type Si͑100͒ substrates with a resistivity of 5-10 ⍀ cm. The Si wafers were cleaned by a standard RCA process and dipped in dilute HF for 30 s to remove the native oxide from the surface before the deposition of dielectric film. An ϳ18 nm Sm 2 TiO 5 film was deposited on the Si substrate by cosputtering Sm and Ti from a Sm target and Ti target in diluted O 2 ͑Ar:O 2 = 5:2͒ ambient. Samples were then annealed at different temperatures in O 2 ͑ϳ5 sccm͒ gas for 30 s by rapid thermal annealing ͑RTA͒ to form a Sm 2 TiO 5 structure. A 1000 Å TiN film was deposited on the Sm 2 TiO 5 by sputtering to serve as the gate electrode. The capacitor area of 3.14 ϫ 10 −4 cm 2 was defined by photolithography and wet etching. Finally, a 4000 Å...

First principles investigation of structural, electronic, elastic and thermal properties of rare-earth-doped titanate Ln2TiO5

“…[1][2][3][4][5][6][7] The applications of Ln 2 TiO 5 compounds range from high-permittivity dielectrics, biomedical sensing [1][2][3][4][5][6][7] to nuclear reactor control rod materials [8][9][10] and nuclear waste forms. 11 Lanthanide oxides as alloying constituents can be used as neutron absorbers in control rods.…”

Material, Electrical, and Optical Characterizations of High-K Sm2TiO5Dielectric Deposited on Polycrystalline Silicon

“…The dielectric was treated with post-RTA annealing as an effective method for lessening defect structures. In contrast to a previous study [9], the high-k Sm 2 TiO 5 capacitors fabricated on polysilicon substrate with proper RTA annealing show great promise for future generation CMOS devices.…”

Structural and electrical characteristics of high-κ Sm2TiO5gate dielectrics for InGaZnO thin-film transistors

“…Kim et al [22] reported that Sm 2 Ti 2 O 7 thin film in metal-insulator-metal capacitor has a high capacitance density and a low leakage current density. In addition, we demonstrated that thin Sm 2 TiO 5 film as gate dielectric materials showed a high capacitance value, a low hysteresis voltage, a small frequency dispersion, and a low leakage current [23]. Although the impact of Ti doping in the Sm 2 O 3 on electrical characteristics of IGZO TFTs was studied in our previous report [24], the physical and electrical properties of the Sm 2 TiO 5 film as a gate dielectric for -IGZO TFT devices are still not known.…”