Gd silicate: A high-k dielectric compatible with high temperature annealing

Abstract

Articles you may be interested inEffects of high-temperature thermal annealing on the electronic properties of In-Ga-Zn oxide thin films J. Vac. Sci. Technol. A 33, 021520 (2015); 10.1116/1.4908157The photoluminescence and structural properties of (Ce, Yb) co-doped silicon oxides after high temperature annealing Gadolinium silicate gate dielectric films with sub-1.5 nm equivalent oxide thicknessThe authors report on the investigation of amorphous Gd-based silicates as high-k dielectrics. Two different stacks of amorphous gadolinium oxide ͑Gd 2 O 3 ͒ and silicon oxide ͑SiO 2 ͒ on silicon substrates are compared after annealing at temperatures up to 1000°C. Subsequently formed metal oxide semiconductor capacitors show a significant reduction in the capacitance equivalent thicknesses after annealing. Transmission electron microscopy, medium energy ion scattering, and x-ray diffraction analysis reveal distinct structural changes such as consumption of the SiO 2 layer and formation of amorphous Gd silicate. The controlled formation of Gd silicates in this work indicates a route toward high-k dielectrics compatible with conventional, gate first complementary metal-oxide semiconductor integration schemes.

Integrations and challenges of novel high-k gate stacks in advanced CMOS technology

“…Base on the observations from different groups, improved interface stability and reduced leakage currents can be achieved by forming the amorphous silicate as candidates. Therefore, it in turn has generated interest in the investigation of silicates such as Gd-silicate [115] and La-silicate [116].…”

“…Recently, due to the reasonably high dielectric constant, the relatively large bandgap, high heat of formation, and superior thermodynamic stability from calculated Gibbs free reaction with Si, Hf (Zr)-based high-k gate dielectrics have been highlighted as one of the most promising candidates for replacing conventional SiO 2 as the gate dielectric in coming devices [15,61,[108][109][110]. Meanwhile, rare earth oxides [2,[111][112][113][114], various lanthanides and their silicates [115,116] are also investigated as potentially promising candidates, despite the fact that in some cases the permittivity increase is only moderate. Quite recently, amorphous ternary rare earth scandates have also been introduced as high-k candidates [117][118][119], e.g., GdScO 3 has been reported to have permittivity value of about 20, which is considerably higher than those of the constituent oxides, Gd 2 O 3 and Sc 2 O 3 .…”

Observation of peripheral charge induced low frequency capacitance-voltage behaviour in metal-oxide-semiconductor capacitors on Si and GaAs substrates

“…15,16 Si surfaces were prepared by RCA cleaning followed by dry thermal oxidation to form SiO 2 interlayers $4 nm thick. 10 nm thick Gd 2 O 3 films were then deposited by electron beam evaporation from granular Gd 2 O 3 at a deposition rate of 0.01 nm/s and molecular nitrogen was present during deposition.…”

“…The samples then underwent RTA for 1 s at 900 C to form GdSiO x from the initial Gd 2 O 3 /SiO 2 bilayer. 15,16 TiN electrodes (50 nm thick) were deposited by reactive sputtering from Ti, and circular capacitors of various areas were defined using a lift-off process. Finally, backside contacts were formed by deposition of Al.…”

“…A k-value of $16 is estimated for the GdSiO x layers. 15,16 For the third sample set examined, the substrates used were (1) n-type GaAs(111B) (Si at $5 Â 10 17 cm…”