Optimization of gadolinium oxide growth deposited on Si by high pressure sputtering

Abstract

Articles you may be interested inOptimization of in situ plasma oxidation of metallic gadolinium thin films deposited by high pressure sputtering on silicon J.Embedded argon as a tool for sampling local structure in thin plasma deposited aluminum oxide films Structural, optical, and electrical characterization of gadolinium oxide films deposited by low-pressure metalorganic chemical vapor deposition High j gadolinium oxide thin layers were deposited on silicon by high-pressure sputtering (HPS). In order to optimize the properties for microelectronics applications, different deposition conditions were used. Ti (scavenger) and Pt (nonreactive) were e-beam evaporated to fabricate metal-insulator-semiconductor (MIS) devices. According to x-ray diffraction, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy, polycrystalline stoichiometric Gd 2 O 3 films were obtained by HPS. The growth rate decreases when increasing the deposition pressure. For relatively thick films (40 nm), a SiO x interface as well as the formation of a silicate layer (GdSiO x ) is observed. For thinner films, in Ti gated devices the SiO x interface disappears but the silicate layer extends over the whole thickness of the gadolinium oxide film. These MIS devices present lower equivalent oxide thicknesses than Pt gated devices due to interface scavenging. The density of interfacial defects D it is found to decrease with deposition pressure, showing a reduced plasma damage of the substrate surface for higher pressures. MIS with the dielectric deposited at higher pressures also present lower flatband voltage shifts DV FB in the C HF -V G hysteresis curves.

Scavenging effect on plasma oxidized Gd2O3grown by high pressure sputtering on Si and InP substrates

“…D it degradation is even more noticeable for the sample with 17 nm of Ti after the FGA at 400 °C, suggesting again that excessive scavenging results in a defective interface. Other works have reported similar values of the D it using ZrO 2 [30], single crystalline Gd 2 O 3 [31] and polycrystalline Gd 2 O 3 with an amorphous GdSiO layer [32].…”

“…The high working pressure of this non-conventional system (three orders of magnitude above conventional sputtering systems) prevents damaging the semiconductor surface due to the low thermalizing length of the particles: at a pressure of 0.5 mbar, the mean free path of the sputtered particles, between 1-3 mm, is much smaller than the target-substrate distance, ∼2.5 cm. Our group has previously used this system to deposit several high κ dielectrics from oxide targets: TiO 2 [19], HfO 2 [20], Sc 2 O 3 [21], Gd 2 O 3 [22] and also, ternary oxides as GdScO 3 [23]. The novelty of the Gd 2 O 3 deposition used in this work follows a work reported by Hoshino et al [24] and consists in the growth of the dielectric film from a metallic Gd target by a two-step process: firstly we deposited a thin film of Gd and then performed, without breaking the vacuum, an Ar/O 2 plasma exposure in order to oxidize the Gd layer.…”

Nano-laminate vs. direct deposition of high permittivity gadolinium scandate on silicon by high pressure sputtering

“…The shift towards lower wavenumber with respect to the ideal SiO 2 band is related 6 to the fact that the interface consists of Si suboxide and/or a stressed interfacial layer [23]. The bands that appear at ~820 and ~910 cm -1 are attributed to the correction of spectra with Si substrate and have been observed in previous works [18,27,28].…”

“…The areas of these curves provide the composition of the films. Quantitative XPS data indicate that both grown binaries are stoichiometric [18,29]. On the other hand, the composition calculated for the ternary oxide obtained from the nano-laminate is Gd 1.8 Sc 0.2 O 3 [28].…”

“…The use of two different targets to deposit the nano-laminate allowed us to control the composition of the ternary Gd 2-x Sc x O 3 through the thicknesses of the layers of the binary oxides. In fact, our purpose was to obtain Gd-rich Gd 2-x Sc x O 3 because of two reasons: it presents higher relative permittivity than other compositions [17] and Gd 2 O 3 presents better stability with Si than Sc 2 O 3 [18]. For the electrical characterization, metal-insulator-semiconductor (MIS) capacitors were fabricated.…”