Interfacial reaction depending on the stack structure of Al2O3 and HfO2 during film growth and postannealing

Abstract

Interfacial reactions as a function of the stack structure of Al2O3 and HfO2 grown on Si by atomic-layer deposition were examined by various physical and electrical measurements. In the case of an Al2O3 film with a buffer layer of HfO2, reactions between the Al2O3 and Si layers were suppressed, while a HfO2 film with an Al2O3 buffer layer on the Si readily interacted with Si, forming a Hf–Al–Si–O compound. The thickness of the interfacial layer increased dramatically after an annealing treatment in which a buffer layer of Al2O3 was used, while no change in thickness was observed in the film in which a HfO2 buffer layer was used. Moreover, the stoichiometric change caused by a different reaction process altered the chemical state of the films, which affected charge trapping and the interfacial trap density.

Self-Heating and Failure in Scalable Graphene Devices

“…This implies a common failure mode. Like SiO 2 , ALD layers of hafnia seeded with alumina begin to degrade near 900 °C 43 44 45 . As shown in the inset to Fig.…”

Reliability of HfAlO<inf>x</inf> in multi layered gate stack

“…Incorporation of aluminum into HfO 2 by forming (HfO 2 ) 1-x (Al 2 O 3 ) x films [1][2][5][6][7][8][9][10][11][12] or HfO 2 /Al 2 O 3 bi-layers [2,[13][14] was reported to be promising for high-κ on silicon and high mobility substrates. The addition of Al into HfO 2 can downscale the equivalent oxide thickness (EOT), reduces the gate leakage current density (J g ) and provides a better thermal stability on Si [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. However, Al concentration in the dielectrics needs to be maintained to an extremely low level for highly scaled transistors.…”

Multilayered ALD HfAlO_x and HfO₂ for High-Quality Gate Stacks

“…The incorporation of aluminum into HfO 2 by forming (HfO 2 ) 1−x (Al 2 O 3 ) x films [1], [2], [5]- [12] or HfO 2 /Al 2 O 3 bi-layers [2], [13], [14] was reported to be promising for high-κ gate dielectrics on silicon and high mobility substrates. [9] demonstrated a significant increase in the amorphous to polycrystalline transition temperature when aluminum was incorporated into HfO 2 .…”

“…Also, Park et al [6] demonstrated the formation of ALD Hf aluminate films with (002) oriented tetragonal phase, which has a higher dielectric constant. For HfO 2 /Al 2 O 3 bilayer structures, Cho et al [13], and Nishimura et al [14] showed improved thermal stability for dielectrics annealed up to 900 • C. A comparative study showed that the incorporation of Al in the alloy form provides a better equivalent oxide thickness (EOT) downscaling potential, along with a reduced gate leakage current as compared to the bilayer form [2]. However, Al diffusion after annealing can introduce fixed charges near the Si/SiO x interface [15].…”