Physical-Chemical Evolution upon Thermal Treatments of Al₂O₃, HfO₂ and Al/Hf Composite Materials Deposited by ALCVD™

Abstract

This paper presents a systematic investigation of thermal stability of high-k materials deposited on RCA cleaned wafers by ALCVD™ in an ASM Pulsar™ 2000 reactor. Physical-chemical evolution of Al2O3, HfO2 and Al/Hf composite materials (nanolaminate and aluminates) was studied considering two types of thermal treatments: quenched vacuum anneals from 300°C to 900°C and furnace atmospheric processes in N2 or O2 at 850°C and 900°C. Material crystallization and changes in film structure were studied by means of TEM, XRD, XRR, XRF, RBS and TOF-SIMS. Non-contact electrical measurements were used to detect modification in EOT and fixed charge. Al2O3 was found still amorphous at 900°C. Not so for HfO2 that crystallized in monoclinic phase at a temperature between 300–400°C. Crystallization temperature and possible phase separation of Al/Hf composite materials were found to be a function of Al2O3 content and film type. In most of these samples, however, a chemical evolution was detected in addition to the above reported crystallization phenomena. All the achieved results demonstrate that depending on thermal treatment conditions, ALCVD™ high-k stability does not only concern phase transition effects but also a transformation of the “SiO2/high-k” system into “doped-SiO2/silicate” stack.

Reduction of Electrical Defects in Atomic Layer Deposited HfO2 Films by Al Doping

“…The V FB increased with increasing Al concentration in the Al:HfO 2 film before and after PDA, as shown in Figure c, because the Al ions in the HfO 2 films act as the negative fixed charges. , This provides advantages for a lower J g at a lower threshold voltage in the operation of p-MOSFET devices. The annealed Al:HfO 2 films also have superior dielectric properties than the annealed control HfO 2 films.…”

Electron Spin Resonance of Interfaces and Nanolayers in Semiconductor Heterostructures

“…As addressed previously, for many (high-k) metal oxides such as, for example, Al 2 O 3 , HfO 2 , and ZrO 2 , deposition of the high-k oxides directly on Si typically results in the formation of an SiO 2(x) -type interlayer [91,125,126,129,145,146,150,159,160]. As addressed previously, for many (high-k) metal oxides such as, for example, Al 2 O 3 , HfO 2 , and ZrO 2 , deposition of the high-k oxides directly on Si typically results in the formation of an SiO 2(x) -type interlayer [91,125,126,129,145,146,150,159,160].…”

“…This was also revealed by numerous topographic/imaging techniques, such as medium energy ion scattering (MEIS), highresolution transmission electron microscopy , and X-ray photoelectron spectroscopy (XPS) [91,125,126,129,159,160]. This was also revealed by numerous topographic/imaging techniques, such as medium energy ion scattering (MEIS), highresolution transmission electron microscopy , and X-ray photoelectron spectroscopy (XPS) [91,125,126,129,159,160].…”

Effects of plasma nitridation of Al2O3 interlayer on thermal stability, fixed charge density, and interfacial trap states of HfO2 gate dielectric films grown by atomic layer deposition

“…11,12,17 Here, the plasmatreatment effects on the CET and V fb of the Al 2 O 3 films were investigated by utilizing the 6-nm-thick Al 2 O 3 films. Therefore, Q f should be reduced to that of SiO 2 /Si or compensated by the countercharges.…”

“…17 By properly treating the Al 2 O 3 layer with NH 3 plasma, positive fixed charges, which are necessary to cancel out the negative fixed charges, can be produced and the V fb ͑and threshold voltage of the MOSFET͒ can be controlled to have the ideal value. 17 By properly treating the Al 2 O 3 layer with NH 3 plasma, positive fixed charges, which are necessary to cancel out the negative fixed charges, can be produced and the V fb ͑and threshold voltage of the MOSFET͒ can be controlled to have the ideal value.…”