Limits...
Polycrystallization effects on the nanoscale electrical properties of high-k dielectrics.

Lanza M, Iglesias V, Porti M, Nafria M, Aymerich X - Nanoscale Res Lett (2011)

Bottom Line: In this study, atomic force microscopy-related techniques have been used to investigate, at the nanoscale, how the polycrystallization of an Al2O3-based gate stack, after a thermal annealing process, affects the variability of its electrical properties.The impact of an electrical stress on the electrical conduction and the charge trapping of amorphous and polycrystalline Al2O3 layers have been also analyzed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept, Eng, Electrònica, Edifici Q, Campus UAB, 08193 Bellaterra, Spain. mario.lanza@uab.cat.

ABSTRACT
In this study, atomic force microscopy-related techniques have been used to investigate, at the nanoscale, how the polycrystallization of an Al2O3-based gate stack, after a thermal annealing process, affects the variability of its electrical properties. The impact of an electrical stress on the electrical conduction and the charge trapping of amorphous and polycrystalline Al2O3 layers have been also analyzed.

No MeSH data available.


Related in: MedlinePlus

TEM images (a, b), topographic maps (c, d), current maps (e, f), and CPD maps (g, h) for amorphous (left column) and polycrystalline (right column) samples. The values of the most relevant parameters are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211152&req=5

Figure 1: TEM images (a, b), topographic maps (c, d), current maps (e, f), and CPD maps (g, h) for amorphous (left column) and polycrystalline (right column) samples. The values of the most relevant parameters are shown.

Mentions: To begin with, a physical analysis of the two samples has been performed with TEM and X-ray Reflectometry. Figure 1 shows cross-sectional TEM images of the sample annealed at (a) 750 and (b) 950°C. Note that the different layers of the stack structure are clearly distinguished (SiO2 interfacial layer and high-k dielectric). Moreover, it can also be observed that the sample annealed at 950°C shows a polycrystalline structure (the different gray intensities in the high-k layer corresponding to the different orientations of the nanocrystals), while the sample annealed at 750°C remains amorphous. These results were confirmed from GIXRD measurements [21]. From TEM images, the crystalline grains seem to have a diameter of 15-30 nm. The surface of the two samples has also been studied from AFM topography maps. Figure 1 shows topographic images obtained on the (c) amorphous and (d) polycrystalline structures. The root mean square (rms) value of the images is also included. Although in this experiment the resolution of the set-up does not allow to distinguish single crystals, the figure indicates an increase of the surface roughness after polycrystallization, in agreement with [11,22]. Finally, since a thermal annealing process can also affect the thickness of the layers of the stack, the actual physical thicknesses of the SiO2 and Al2O3 films were determined from X-ray Reflectometry (Table 1). Note that, after polycrystallization, a reduction in the thickness of the high-k layer is observed [23], leading to a smaller equivalent oxide thickness (EOT) [17].


Polycrystallization effects on the nanoscale electrical properties of high-k dielectrics.

Lanza M, Iglesias V, Porti M, Nafria M, Aymerich X - Nanoscale Res Lett (2011)

TEM images (a, b), topographic maps (c, d), current maps (e, f), and CPD maps (g, h) for amorphous (left column) and polycrystalline (right column) samples. The values of the most relevant parameters are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211152&req=5

Figure 1: TEM images (a, b), topographic maps (c, d), current maps (e, f), and CPD maps (g, h) for amorphous (left column) and polycrystalline (right column) samples. The values of the most relevant parameters are shown.
Mentions: To begin with, a physical analysis of the two samples has been performed with TEM and X-ray Reflectometry. Figure 1 shows cross-sectional TEM images of the sample annealed at (a) 750 and (b) 950°C. Note that the different layers of the stack structure are clearly distinguished (SiO2 interfacial layer and high-k dielectric). Moreover, it can also be observed that the sample annealed at 950°C shows a polycrystalline structure (the different gray intensities in the high-k layer corresponding to the different orientations of the nanocrystals), while the sample annealed at 750°C remains amorphous. These results were confirmed from GIXRD measurements [21]. From TEM images, the crystalline grains seem to have a diameter of 15-30 nm. The surface of the two samples has also been studied from AFM topography maps. Figure 1 shows topographic images obtained on the (c) amorphous and (d) polycrystalline structures. The root mean square (rms) value of the images is also included. Although in this experiment the resolution of the set-up does not allow to distinguish single crystals, the figure indicates an increase of the surface roughness after polycrystallization, in agreement with [11,22]. Finally, since a thermal annealing process can also affect the thickness of the layers of the stack, the actual physical thicknesses of the SiO2 and Al2O3 films were determined from X-ray Reflectometry (Table 1). Note that, after polycrystallization, a reduction in the thickness of the high-k layer is observed [23], leading to a smaller equivalent oxide thickness (EOT) [17].

Bottom Line: In this study, atomic force microscopy-related techniques have been used to investigate, at the nanoscale, how the polycrystallization of an Al2O3-based gate stack, after a thermal annealing process, affects the variability of its electrical properties.The impact of an electrical stress on the electrical conduction and the charge trapping of amorphous and polycrystalline Al2O3 layers have been also analyzed.

View Article: PubMed Central - HTML - PubMed

Affiliation: Dept, Eng, Electrònica, Edifici Q, Campus UAB, 08193 Bellaterra, Spain. mario.lanza@uab.cat.

ABSTRACT
In this study, atomic force microscopy-related techniques have been used to investigate, at the nanoscale, how the polycrystallization of an Al2O3-based gate stack, after a thermal annealing process, affects the variability of its electrical properties. The impact of an electrical stress on the electrical conduction and the charge trapping of amorphous and polycrystalline Al2O3 layers have been also analyzed.

No MeSH data available.


Related in: MedlinePlus