Crystallisation kinetics and density profiles in ultra-thin hafnia films

Lee, A. van der; Durand, J.; Blin, D.; Holliger, P.; Martín, F.

doi:10.1140/epjb/e2004-00190-1

Cited by 9 publications

(4 citation statements)

References 15 publications

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“…At the oxide surface and oxide/metal interface accumulation of carbon and chlorine is evident, consistent with the earlier observations on increasing impurity levels at interfaces. [43][44][45] Carbon contamination in the films was quite low. Although no quantitative data are presented due to the absence of calibration, we can safely consider the carbon content well below 0.1 atom%.…”

Section: Resultsmentioning

confidence: 95%

“…In the case of halide-based ALD and temperatures above 300°C, crystallization is promoted and stable capacitance observed in HfO 2 ͑or ZrO 2 ͒ films with thickness below 50 nm. [40][41][42][43] It has been noticed earlier that in the HfO 2 films with thickness below 10 nm the crystallization temperature tends to increase due to considerable residual chlorine content 42,44,45 The content of residues, such as chlorine, at the same time increases with the decrease in growth temperature. However, other studies have shown that the films can crystallize noticeably also within the thickness range of 3-10 nm, 42,[46][47][48] referring to rather complicated interdependences between crystal growth, temperature, reactor/precursor pressure, and ALD cycle time parameters, which cannot be regarded as a well-studied area.…”

Section: Resultsmentioning

confidence: 96%

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Atomic Layer Deposition and Characterization of HfO[sub 2] Films on Noble Metal Film Substrates

Kukli

Aaltonen

Aarik

et al. 2005

J. Electrochem. Soc.

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HfO 2 films were grown by atomic layer deposition from HfCl 4 and H 2 O on atomic layer deposited 40-70 nm thick platinum, iridium, and ruthenium films in the temperature range 200-600°C. The phase formed in the 30-50 nm thick HfO 2 films was monoclinic HfO 2 dominating over amorphous material without noticeable contribution from metastable crystallographic polymorphs. The metal-dielectric-metal capacitor structures formed after evaporating Al gate electrodes demonstrated effective permittivity values in the range 11-16 and breakdown fields reaching 5 MV/cm. Iridium electrode films showed the highest stability in terms of reliability and reproducibility of dielectric characteristics.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 96%

Atomic Layer Deposition and Characterization of HfO[sub 2] Films on Noble Metal Film Substrates

Kukli

Aaltonen

Aarik

et al. 2005

J. Electrochem. Soc.

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“…The rms surface roughness values of the Al 2 O 3 films a−h measured using XRR are summarized in Table and Figure . It is worth noticing that the XRR-determined rms surface roughness differs from the one measured using AFM because it takes into account not only the physical roughness but also the electronic density variations at the film/air interface . However, the trends determined using both techniques are similar.…”

Section: Methodsmentioning

confidence: 97%

Ozone-Based Atomic Layer Deposition of Alumina from TMA: Growth, Morphology, and Reaction Mechanism

Elliott¹,

Scarel²,

Wiemer³

et al. 2006

Chem. Mater.

177

197

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We examine the effect of growth temperature in the 150−300 °C range on the structural and morphological properties of Al2O3 films deposited using atomic layer deposition, contrasting the effect of H2O and O3 as oxygen sources. Trimethylaluminum (TMA) is the metal source. A mechanism for the O3 reaction is investigated using ab initio calculations and provides an explanation for the observed temperature dependence. The simulations show that hydroxyl groups are produced at the surface by the oxidation of adsorbed methyl groups by O3. This is confirmed by the measured rates; both H2O and O3 processes show molar growth rates per cycle that decrease with increasing reactor temperature, consistent with a decrease in hydroxyl coverage. At no temperature does the O3 process deposit more Al2O3 per cycle than the H2O process. Morphological characterization shows that O3 as the oxygen source yields lower-quality films than H2O; the films are less dense and rougher, especially at low growth temperatures. The existence of voids correlates with the low film electronic density. This may indicate the low mobility of surface hydroxyl at low temperatures, an effect that is washed out by repeated exchange with the vapor phase in the H2O case.

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“…Generally, because AFM measures the surface morphology of the topmost layer only, the rms roughness values derived from AFM images should be compared with the roughness values derived from the XRR fittings for the capping layer ͑see Table I͒. Moreover, XRR roughness values might be overestimated, because XRR does not distinguish between physical roughness and density variations, 39 while AFM is sensitive to the physical roughness only. The lateral resolution of the oxidized Si AFM probes used in these measurements might be reduced in contact with the oxide surface, due to the water meniscus formed between two hygroscopic solids.…”

Section: Discussionmentioning

confidence: 99%

Atomic Layer Deposition of Lu Silicate Films Using [(Me[sub 3]Si)[sub 2]N][sub 3]Lu

Scarel¹,

Wiemer²,

Tallarida³

et al. 2006

J. Electrochem. Soc.

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Rare-earth silicates are promising materials for future microelectronic devices based on high dielectric constant dielectrics. In this work, we report the investigation of Lu silicate films deposited using atomic layer deposition on Si͑100͒. The films were grown from tris͓bis͑trimethylsilyl͒amido͔lutetium-͓͑Me 3 Si͒ 2 N͔ 3 Lu ͑where Me = CH 3 ͒, which can supply both Lu and Si. Water or ozone were used as oxygen sources. The films deposited using the latter are shown to be richer in Si. The films are amorphous as grown, have a low physical roughness, an electronic density lower than expected for both crystalline and amorphous stoichiometric Lu silicates, and promote a SiO 2 -rich interfacial layer on Si͑100͒. Crystallization, observed only in films deposited using O 3 , has an onset temperature above 900°C. Annealing at 950°C induces film densification. Signs of crystallization are observed only in the electron diffraction patterns of the annealed film deposited using O 3 as oxygen source, but the resulting crystallographic phases cannot be unequivocally identified. The values of the dielectric stacks are between 5 and 7. The conduction band offset between the Lu silicate layer and Si͑100͒ measured for the film deposited using O 3 is 2.2 eV.High dielectric constant ͑͒ materials are proposed to substitute SiO 2 as insulating layer in complementary metal-oxidesemiconductor devices. 1 For this purpose, in addition to a high value, a large conduction band offset ͑CBO͒ and the thermodynamical stability on silicon are required. Rare-earth ͑RE͒ oxides and silicates are high-materials generally satisfying these requirements. [2][3][4][5] In addition, Lu silicates are expected to exhibit a high crystallization temperature, and high transverse optical ͑TO͒ mode frequencies ͑and therefore moderate remote phonon scattering 6 ͒. All these properties make these materials interesting for applications in microelectronics. 1 This work investigates Lu silicate films grown by atomic layer deposition ͑ALD͒, a technique employed in microelectronics because of the smoothness, conformality, 7 and good electrical characteristics 8 of the deposited films. For RE silicates, there are in general two approaches for their growth using ALD. One is to use Si-containing RE precursors; the other involves a precursor for Si and another one for the RE element. In both cases, oxygen sources such as O 2 , O 3 , or H 2 O are needed to form SiO 3 2− species. The first approach is appealing because it does not require Si precursors, often delivered as flammable, explosive, toxic, or even pyrophoric gases or liquids. Thus we are interested in the first approach 9 and therefore in molecular species in which a direct RE-Si bond exists. To date few such complexes are known. 10 Among them, the low coordinate RE bis͑trimethylsilyl͒amides complexes ͓͑Me 3 Si͒ 2 N͔ 3 RE ͓where RE = Sc, 11 Y, 12 Ce, 13 Nd, 14 Eu, 11 Dy, and Er, 15 Yb ͑Ref. 16͔͒ are worthy of mention because in some of them an agostic interaction of the central RE atom with the methyl groups and...

show abstract

Crystallisation kinetics and density profiles in ultra-thin hafnia films

Cited by 9 publications

References 15 publications

Atomic Layer Deposition and Characterization of HfO[sub 2] Films on Noble Metal Film Substrates

Atomic Layer Deposition and Characterization of HfO[sub 2] Films on Noble Metal Film Substrates

Ozone-Based Atomic Layer Deposition of Alumina from TMA: Growth, Morphology, and Reaction Mechanism

Atomic Layer Deposition of Lu Silicate Films Using [(Me[sub 3]Si)[sub 2]N][sub 3]Lu

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