Thermal stability of ultrathin ZrO2 films prepared by chemical vapor deposition on Si(100)

Jeon, T.S.; White, J. M.; Kwong, D. L.

doi:10.1063/1.1339994

Cited by 259 publications

(126 citation statements)

References 14 publications

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“…Thereby the formation of a thin interfacial layer (oxides, silicates and silicides) between the HfO 2 and the Si surface, has been recently observed [2,3]. This interfacial layer occurs during almost any film growth processes or post-annealing, which is an intrinsic part of any growth cycle.…”

Section: Pacs Numbersmentioning

confidence: 99%

Comparative study of defect energetics in HfO2 and SiO2

Scopel

Silva

Orellana

et al. 2004

Applied Physics Letters

125

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We perform ab initio calculations, based on density functional theory, of substitutional and vacancy defects in the monoclinic hafnium oxide (m-HfO2) and α-quartz (SiO2). The neutral oxygen vacancies and substitutional Si and Hf defects in HfO2 and SiO2, respectively, are investigated. Our calculations show that, for a large range of Hf chemical potential, Si substitutional defects are most likely to form in HfO2, leading to the formation of a silicate layer at the HfO2/Si interface. We also find that it is energetically more favorable to form oxygen vacancies in SiO2 than in HfO2, which implies that oxygen deficient HfO2 grown on top of SiO2 will consume oxygen from the SiO2. PACS numbers:The continuous device miniaturization in the microelectronic industry will eventually lead, within the present technology, to the end of the use of amorphous SiO 2 (a-SiO 2 ) as gate dielectric in metal-oxidesemiconductor field-effect transistors (MOSFETs). The existence of a thickness limit for the a-SiO 2 around 10-12 A, has clearly been established experimentally [1]. One way to circumvent this problem, still keeping Si as the basic device material, is to employ high-permitivity materials as alternative gate dielectrics in place of the conventional a-SiO 2 . Among them, hafnium oxide is emerging as the material with greatest potential to substitute SiO 2 , mainly due to its high dieletric constant and thermodynamic stability, when it forms interface with Si.Even though hafnium oxide is thermodynamically stable against an overall decomposition as Hf and SiO 2 when grown on Si, interfacial reactions can occur. Thereby the formation of a thin interfacial layer (oxides, silicates and silicides) between the HfO 2 and the Si surface, has been recently observed [2,3]. This interfacial layer occurs during almost any film growth processes or post-annealing, which is an intrinsic part of any growth cycle. Therefore, the thermodynamic stability of the hafnium oxide in contact with silicon is identified as a critical issue for the application of alternative gate dielectric in silicon-based devices [4,5]. Moreover, the study of possible defects related to the migration of atoms across the interface is of fundamental importance. In particular, a significant source of defects in this system is the interface itself, which has been shown [6] to consist of Hf silicates with dielectric constant lower than that of HfO 2 [7,8].In the present work we address the formation of neutral defects through first-principles calculations, based on the density functional theory (DFT). We analyze the formation of Si substitutional defects in HfO 2 , as well as Hf substitutional defects in SiO 2 , for different growth conditions. Finally, the energetics of an oxygen vacancy in SiO 2 is compared to a similar vacancy in HfO 2 , in order to understand the growth of hafnium oxide under oxygen-poor conditions. * Electronic address: fazzio@if.usp.br Many experimental works [9,10,11,12] have addressed the chemical reactions that could occur in the HfO 2 /Si interfa...

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Section: Pacs Numbersmentioning

confidence: 99%

Comparative study of defect energetics in HfO2 and SiO2

Scopel

Silva

Orellana

et al. 2004

Applied Physics Letters

125

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“…However, thermodynamic stability analysis considering only reactions between two stoichiometric solids appears to be insufficient for predicting stable heterointerfaces. Interfacial phases, such as silicides, SiO 2 , and silicates, are often observed in real high-k dielectric gate stacks exposed to high temperatures [3][4][5][6][7][8][9][10][11][12][13][14], as schematically illustrated in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…Interfacial silicides form under reducing conditions [3][4][5]15,16], while silicate layers are often observed at interfaces between Si and rare-earth or related oxides. While the experimental conditions under which these layers form are relatively well understood, significant disparity exists in the literature with respect to the reactions causing the formation of interfacial layers, in particular the silicides [4][5][6][7][8][9]17,18].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic considerations in the stability of binary oxides for alternative gate dielectrics in complementary metal–oxide–semiconductors

Stemmer¹

2004

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

111

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A number of binary oxides have been predicted to be thermodynamically stable in contact with Si and are candidates to replace SiO 2 in CMOS. However, reactions leading to the formation of interfacial silicide, silicate or SiO 2 layers have been reported when these oxides are exposed to high temperatures during device processing. Different pathways have been proposed in the literature to explain these reactions. In this paper, a thermodynamic analysis of the proposed reactions is performed. The analysis includes gaseous species, because typical gate dielectrics are ultra-thin layers and diffusivities for species from the surrounding atmosphere, such as oxygen, may be high. Furthermore, nonstoichiometry of the high-k oxide, as may be resulting from nonequilibrium deposition processes or reducing atmospheres during processing is also considered. Studies are proposed to distinguish between possible reaction mechanisms. Finally guidelines for stable interfaces are presented.3

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“…Many experimental studies of high-k materials such as aluminum oxide (Al 2 O 3 ), hafnium oxide (HfO 2 ), and zirconium oxide (ZrO 2 ) grown by atomic layer deposition (ALD) have been reported. [4][5][6][7][8][9][10][11][12][13][14] The ALD technique can control the uniformity and thickness of films on substrate surfaces at an atomic scale. 15,16 The important thing for the ALD process is the initial reaction between the molecule and surface, because it determines the high-k/surface interface structure.…”

Section: Introductionmentioning

confidence: 99%

Reaction of Tri-methylaluminum on Si (001) Surface for Initial Aluminum Oxide Thin-Film Growth

Kim¹,

Kim²,

Jeong³

et al. 2010

Bulletin of the Korean Chemical Society

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We studied the reaction of tri-methylaluminum (TMA) on hydroxyl (OH)-terminated Si (001) surfaces for the initial growth of aluminum oxide thin-films using density functional theory. TMA was adsorbed on the oxygen atom of OH due to the oxygen atom's lone pair electrons. The adsorbed TMA reacted with the hydrogen atom of OH to produce a di-methylaluminum group (DMA) and methane with an energy barrier of 0.50 eV. Low energy barriers in the range of 0 -0.11 eV were required for DMA migration to the inter-dimer, intra-dimer, and inter-row sites on the surface. A unimethylaluminum group (UMA) was generated at each site with low energy barriers in the range of 0.21 -0.25 eV. Among the three sites, the inter-dimer site was the most probable for UMA formation.

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Thermal stability of ultrathin ZrO2 films prepared by chemical vapor deposition on Si(100)

Cited by 259 publications

References 14 publications

Comparative study of defect energetics in HfO2 and SiO2

Comparative study of defect energetics in HfO2 and SiO2

Thermodynamic considerations in the stability of binary oxides for alternative gate dielectrics in complementary metal–oxide–semiconductors

Reaction of Tri-methylaluminum on Si (001) Surface for Initial Aluminum Oxide Thin-Film Growth

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