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Fabrication of HfO2 patterns by laser interference nanolithography and selective dry etching for III-V CMOS application.

Benedicto M, Galiana B, Molina-Aldareguia JM, Monaghan S, Hurley PK, Cherkaoui K, Vazquez L, Tejedor P - Nanoscale Res Lett (2011)

Bottom Line: Pattern transfer to the HfO2 film was carried out by reactive ion beam etching using CF4 and O2 plasmas.A combination of atomic force microscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy microanalysis was used to characterise the various etching steps of the process and the resulting HfO2/GaAs pattern morphology, structure, and chemical composition.We show that the patterning process can be applied to fabricate uniform arrays of HfO2 mesa stripes with tapered sidewalls and linewidths of 100 nm.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain. ptejedor@icmm.csic.es.

ABSTRACT
Nanostructuring of ultrathin HfO2 films deposited on GaAs (001) substrates by high-resolution Lloyd's mirror laser interference nanolithography is described. Pattern transfer to the HfO2 film was carried out by reactive ion beam etching using CF4 and O2 plasmas. A combination of atomic force microscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy microanalysis was used to characterise the various etching steps of the process and the resulting HfO2/GaAs pattern morphology, structure, and chemical composition. We show that the patterning process can be applied to fabricate uniform arrays of HfO2 mesa stripes with tapered sidewalls and linewidths of 100 nm. The exposed GaAs trenches were found to be residue-free and atomically smooth with a root-mean-square line roughness of 0.18 nm after plasma etching.PACS: Dielectric oxides 77.84.Bw, Nanoscale pattern formation 81.16.Rf, Plasma etching 52.77.Bn, Fabrication of III-V semiconductors 81.05.Ea.

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AFM images of the HfO2 nanopattern. (a) Three-dimensional view of the nanostructured HfO2/GaAs surface morphology. (b) Cross-section scan profile of an etched trench.
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Figure 1: AFM images of the HfO2 nanopattern. (a) Three-dimensional view of the nanostructured HfO2/GaAs surface morphology. (b) Cross-section scan profile of an etched trench.

Mentions: The surface morphology of the as-deposited and nanostructured HfO2/GaAs samples was examined by AFM. The root-mean-square (r.m.s.) surface roughness (σ) extracted from 2 × 2-μm AFM images was found to be 0.7 ± 0.01 nm for the as-deposited HfO2 film and 4.9 ± 0.01 for the nanostructured HfO2/GaAs sample. Figure 1 depicts a three-dimensional image (1.2 × 1.2 μm) of the HfO2/GaAs surface topography after nanostructuring and a typical scan profile across an etched trench. The latter revealed the formation of a tapered sidewall due to directional chemical etching and the presence of re-deposited reaction by-products on the edges of the HfO2 mesa stripes. The values of the r.m.s. line roughness (Ra) measured along the HfO2 stripes and the etched GaAs trenches were 0.14 ± 0.03 nm and 0.18 ± 0.03 nm, respectively. The value of the GaAs line roughness measured in this work is comparable to that reported previously for HfO2 etching using a SF6/Ar plasma (0.13 nm) [8]. Etching with a CF4 plasma chemistry thus provides an atomically smooth GaAs surface, which is a critical requirement for subsequent selective III-V growth during device fabrication. In fact, preliminary III-V molecular beam epitaxy experiments to be reported elsewhere indicate that both the quality of the starting GaAs surface and the inclined sidewalls of the HfO2 nanopatterns are adequate for selective area growth and the resulting III-V nanostructures do not suffer from microtrench formation near the high-κ gate oxide, reported by other authors [10].


Fabrication of HfO2 patterns by laser interference nanolithography and selective dry etching for III-V CMOS application.

Benedicto M, Galiana B, Molina-Aldareguia JM, Monaghan S, Hurley PK, Cherkaoui K, Vazquez L, Tejedor P - Nanoscale Res Lett (2011)

AFM images of the HfO2 nanopattern. (a) Three-dimensional view of the nanostructured HfO2/GaAs surface morphology. (b) Cross-section scan profile of an etched trench.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211495&req=5

Figure 1: AFM images of the HfO2 nanopattern. (a) Three-dimensional view of the nanostructured HfO2/GaAs surface morphology. (b) Cross-section scan profile of an etched trench.
Mentions: The surface morphology of the as-deposited and nanostructured HfO2/GaAs samples was examined by AFM. The root-mean-square (r.m.s.) surface roughness (σ) extracted from 2 × 2-μm AFM images was found to be 0.7 ± 0.01 nm for the as-deposited HfO2 film and 4.9 ± 0.01 for the nanostructured HfO2/GaAs sample. Figure 1 depicts a three-dimensional image (1.2 × 1.2 μm) of the HfO2/GaAs surface topography after nanostructuring and a typical scan profile across an etched trench. The latter revealed the formation of a tapered sidewall due to directional chemical etching and the presence of re-deposited reaction by-products on the edges of the HfO2 mesa stripes. The values of the r.m.s. line roughness (Ra) measured along the HfO2 stripes and the etched GaAs trenches were 0.14 ± 0.03 nm and 0.18 ± 0.03 nm, respectively. The value of the GaAs line roughness measured in this work is comparable to that reported previously for HfO2 etching using a SF6/Ar plasma (0.13 nm) [8]. Etching with a CF4 plasma chemistry thus provides an atomically smooth GaAs surface, which is a critical requirement for subsequent selective III-V growth during device fabrication. In fact, preliminary III-V molecular beam epitaxy experiments to be reported elsewhere indicate that both the quality of the starting GaAs surface and the inclined sidewalls of the HfO2 nanopatterns are adequate for selective area growth and the resulting III-V nanostructures do not suffer from microtrench formation near the high-κ gate oxide, reported by other authors [10].

Bottom Line: Pattern transfer to the HfO2 film was carried out by reactive ion beam etching using CF4 and O2 plasmas.A combination of atomic force microscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy microanalysis was used to characterise the various etching steps of the process and the resulting HfO2/GaAs pattern morphology, structure, and chemical composition.We show that the patterning process can be applied to fabricate uniform arrays of HfO2 mesa stripes with tapered sidewalls and linewidths of 100 nm.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, C/Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain. ptejedor@icmm.csic.es.

ABSTRACT
Nanostructuring of ultrathin HfO2 films deposited on GaAs (001) substrates by high-resolution Lloyd's mirror laser interference nanolithography is described. Pattern transfer to the HfO2 film was carried out by reactive ion beam etching using CF4 and O2 plasmas. A combination of atomic force microscopy, high-resolution scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy microanalysis was used to characterise the various etching steps of the process and the resulting HfO2/GaAs pattern morphology, structure, and chemical composition. We show that the patterning process can be applied to fabricate uniform arrays of HfO2 mesa stripes with tapered sidewalls and linewidths of 100 nm. The exposed GaAs trenches were found to be residue-free and atomically smooth with a root-mean-square line roughness of 0.18 nm after plasma etching.PACS: Dielectric oxides 77.84.Bw, Nanoscale pattern formation 81.16.Rf, Plasma etching 52.77.Bn, Fabrication of III-V semiconductors 81.05.Ea.

No MeSH data available.


Related in: MedlinePlus