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

High κ 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 Gd₂O₃ 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 ΔV_FB in the C_HF–V_G hysteresis curves.