Gadolinium silicate gate dielectric films with sub-1.5 nm equivalent oxide thickness

Abstract

GdSi x O y gate dielectric films were deposited on Si(001) substrates using ultra-high-vacuum electron-beam evaporation from pressed-powder targets. Transmission electron microscopy showed that the films were amorphous as deposited and remained amorphous when annealed to temperatures up to 900 °C. Capacitance–voltage measurements indicate an equivalent oxide thickness (EOT) of 13.4 Å for a film with composition GdSi0.56O2.59 determined by in situ x-ray photoelectron emission spectroscopy. After forming gas annealing at 500 °C the EOT was reduced to 11.0 Å, at a physical thickness of 45 Å. The same film has a low leakage current of approximately 5.7×10−3 A cm−2 at +1 V, a reduction of 8.7×104 compared to current density estimates of SiO2 films with the same specific capacitance.

Effect Of The Gadolinium Oxide Addition On The Electrical Properties Of Tetragonal Zirconium Dioxide

“…Basing on the fact, that Gd 2 O 3 easily forms silicates with silica [24,25] we tested Gd 2 O 3 dopant serving as a new silica scavenger, which modifies grain boundary properties of tetragonal ZrO 2 stabilized by Y 2 O 3 .…”

Characterization of gadolinium and lanthanum oxide films on Si (100)

“…4,5 The silicate films, which remain amorphous at relatively high temperature, might provide a better interface with Si than the metal-oxide and show the most promise for successful integration into future CMOS technologies. In this article, we report the physical and chemical characterization of gadolinium and lanthanum oxide films on Si ͑100͒ and describe the formation of lanthanum and gadolinium silicates by annealing these oxide films.…”

Thermal stability and diffusion in gadolinium silicate gate dielectric films

“…Previous work 8 has shown that gadolinium silicate films with as high as 16 have promising electrical properties that may make them a very good replacement for SiO 2 as the gate insulator. In this letter, we investigate the motion of Si and O 2 in gadolinium silicate films to show that their stability against diffusion could be superior to that of other highdielectrics.…”

“…1 O 3 , and silicates such as ZrSiO 4 and HfSiO 4 . [2][3][4] It is generally assumed that other lanthanide oxides, such as Gd 2 O 3 , [5][6][7] or their silicates, 8 are also thermodynamically stable. However, even a thermodynamically stable film can react if excess oxygen in the film or from the ambient, or Si from the substrate, diffuse through the film and react with each other.…”