Plasma-enhanced atomic layer deposited HfO2 films using a novel heteroleptic cyclopentadienyl-based Hf precursor

Baek, Ji hoon; Choi, Woong; Kim, Hohoon; Cheon, Seonghak; Byun, Younghun; Jeon, Woojin; Park, Jin‐Seong

doi:10.1016/j.ceramint.2021.07.065

Cited by 8 publications

(7 citation statements)

References 43 publications

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“…When the substrate temperature is further enhanced to a higher temperature, the density of HfO 2 films deteriorates due to the grain boundary and CVD-like reaction. The highest density of 10.22 g/cm 3 obtained in this work is comparable to the reported density of HfO 2 film using a MAP-Hf01 precursor and Ar/O 2 plasma by Ji-hoon Baaek et al [ 39 ]. The thicknesses of HfO 2 films prepared 500 reaction cycles extracted from XRR are 64.7 nm, 46.4 nm,42.2 nm, 66.3 nm and 87.5 nm, respectively.…”

Section: Resultssupporting

confidence: 87%

“…All of the extracted k values of HfO 2 films at various substrate temperatures agree with the reported ALD-grown HfO 2 film. In this study, the highest obtained k value of 18.21 at the substrate temperature of 300 °C is higher than most of the other reported PEALD-grown HfO 2 films [ 39 , 44 , 45 ], although it is slightly lower than the k value of 18.60 [ 46 ] prepared by PEALD with post deposition annealing and 18.3 [ 47 ] prepared by high power impulse magnetron sputtering (HIPIMS). The data of the breakdown electric field and density are not provided in references [ 46 , 47 ].…”

Section: Resultscontrasting

confidence: 58%

“…When the substrate temperature was 300 °C, the devices obtained the highest breakdown electric field, with the value of 5.88 MV/cm. The decreasing value of the breakdown electric field for the devices prepared at the temperatures higher than 300 °C may be ascribed to the highly crystallized HfO 2 films that have a percolation path under the high electrical field due to the high density of the grain boundary defects [ 39 ]. The variation in the breakdown electric field is similar to the variation in k. This behavior is caused by the approximate breakdown electric field, E bd ~ (k) −1/2 relation, illustrated by J. McPherson et al [ 43 ].…”

Section: Resultsmentioning

confidence: 99%

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Crystallinity Effect on Electrical Properties of PEALD–HfO2 Thin Films Prepared by Different Substrate Temperatures

et al. 2022

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Hafnium oxide (HfO2) thin film has remarkable physical and chemical properties, which makes it useful for a variety of applications. In this work, HfO2 films were prepared on silicon through plasma enhanced atomic layer deposition (PEALD) at various substrate temperatures. The growth per cycle, structural, morphology and crystalline properties of HfO2 films were measured by spectroscopic ellipsometer, grazing-incidence X-ray diffraction (GIXRD), X-ray reflectivity (XRR), field-emission scanning electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy. The substrate temperature dependent electrical properties of PEALD–HfO2 films were obtained by capacitance–voltage and current–voltage measurements. GIXRD patterns and XRR investigations show that increasing the substrate temperature improved the crystallinity and density of HfO2 films. The crystallinity of HfO2 films has a major effect on electrical properties of the films. HfO2 thin film deposited at 300 °C possesses the highest dielectric constant and breakdown electric field.

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Section: Resultssupporting

confidence: 87%

Section: Resultscontrasting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

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Crystallinity Effect on Electrical Properties of PEALD–HfO2 Thin Films Prepared by Different Substrate Temperatures

et al. 2022

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“…These values are similar to or better than those previously reported for MIS capacitors fabricated using a HfO 2 layer prepared from solid or heteroleptic ALD precursors. [13][14][15]20,24,26 The leakage current density of the MIS capacitor at 1 MV/cm was 1.2 × 10 −7 A/cm 2 and did not substantially change upon annealing at 600 °C for 1 min. Thus, these results indicate that a HfO 2 layer with a high electronic performance could be attained even when a liquid ALD precursor [Hf(dmap) 4 ] was used.…”

Section: Characterization Of Hfo 2 Films Deposited By Hf-(dmap) 4 Pre...mentioning

confidence: 95%

Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications

Nishida,

Katayama,

Matsuo

2023

ACS Appl. Nano Mater.

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Atomic layer deposition (ALD) of HfO2 thin films was studied by using a novel Cl-free hafnium ALD precursor: tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)4]. This precursor is a liquid at room temperature and has been shown by differential scanning calorimetry (DSC) analysis to be stable at temperatures as high as 371 °C. Compared with the conventional Hf precursor tetrakis(ethylmethylamido)hafnium(IV) (TEMAH), Hf(dmap)4 exhibits a substantially greater decomposition temperature because of its alkoxide structure. Hf(dmap)4 is a volatile compound that shows a very clean thermogravimetry curve without decomposition or residue formation at 10 Torr. We performed ALD of HfO2 using Hf(dmap)4 with an oxidant of either O3 or H2O as an oxidant. As the wafer temperature was increased from 250 to 400 °C, the film growth rate slightly increased from 0.35 to 0.55 Å/cycle. Therefore, Hf(dmap)4 can be used for ALD at higher deposition temperatures than for TEMAH. However, the film growth rate was lowered by the sterically hindered ligand structure of the precursor. We evaluated the saturation behavior of the growth rate in experiments in which the Hf(dmap)4 supply time was varied from 5 to 30 s. As a result, a constant film growth rate was observed because of ALD saturation when the precursor supply time was 10 s or longer in the temperature range 350–400 °C. This result indicates that Hf(dmap)4 was not decomposed and behaved as an ALD precursor at 400 °C. We concluded that Hf(dmap)4 is a promising precursor for high-temperature ALD of HfO2 film for gate dielectrics, high-K capacitors, and HfO2-based ferroelectrics.

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“…These precursors, however, sometimes have drawbacks such as halide contamination and low stabilities in the case of the halide and alkoxides, respectively. Consequently, heteroleptic precursors including more than one type of ligands such as cyclopentadienyl (Cp)-alkoxides and Cp-alkylamides are developed, to enhance the thermal stability of precursors of the ALD high-k oxides. − When ozone is used as the oxygen source, ALD using zirconium and hafnium Cp-alkylamide precursors shows high growth per cycle (GPC), ranging from 0.8 to 0.9 Å per cycle, and the deposited films mostly possessed low levels of nitrogen and carbon contamination. Especially, ZrO 2 and HfO 2 films deposited using CpZr(N(Me 2 ) 3 and CpHf(N(Me 2 ) 3 precursors (Me = CH 3 ) and ozone have shown improved film density and electrical performance, possibly due to the deposition temperatures being as high as 350 °C.…”

Section: Introductionmentioning

confidence: 99%

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

et al. 2022

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Deposition of high-k dielectric thin films is essential for manufacturing modern electronic devices. Atomic layer deposition (ALD) is an attractive technology for depositing high-k materials because it exhibits conformality and facilitates thickness control of the films at the atomic level. It has been suggested that high-temperature ALD can enhance the material properties of the deposited films such as density and crystallinity, for which the development of thermally stable precursors that deliver the metallic element is required. Heteroleptic titanium (Ti), zirconium (Zr), and hafnium (Hf) precursors containing amido and cyclopentadienyl (Cp) ligands have recently been introduced, with some demonstrating improved thermal stability. However, the mechanism behind the improved thermal stability of these precursors remains unclear. This research employs density functional theory (DFT) calculations to elucidate the role of Cp ligands of group 4 (Ti, Zr, Hf) precursors for high-temperature ALD. The surface adsorption reactions of the precursors on oxide surfaces are suggested to be facile. For most precursors, one or two ligands are thought to exist after chemical adsorption. Cp ligands, in particular, are expected to persist on the surface, whereas amido ligands are more easily eliminated during adsorption. The decomposition of the precursor after adsorption on the surface then is considered, for which the thermal stability is significantly enhanced by introducing the Cp ligand. Furthermore, precursors with Cp ligands are more difficult to adsorb on the partially decomposed precursor-on-surface. Our findings intend to offer a fundamental molecular-level understanding of the thermal stability of group 4 precursors for high-temperature ALD.

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Plasma-enhanced atomic layer deposited HfO2 films using a novel heteroleptic cyclopentadienyl-based Hf precursor

Cited by 8 publications

References 43 publications

Crystallinity Effect on Electrical Properties of PEALD–HfO2 Thin Films Prepared by Different Substrate Temperatures

Crystallinity Effect on Electrical Properties of PEALD–HfO2 Thin Films Prepared by Different Substrate Temperatures

Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

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Plasma-enhanced atomic layer deposited HfO2 films using a novel heteroleptic cyclopentadienyl-based Hf precursor

Cited by 8 publications

References 43 publications

Crystallinity Effect on Electrical Properties of PEALD–HfO2 Thin Films Prepared by Different Substrate Temperatures

Crystallinity Effect on Electrical Properties of PEALD–HfO2 Thin Films Prepared by Different Substrate Temperatures

Atomic Layer Deposition of HfO2 Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)4] for Advanced Gate Dielectrics Applications

Role of Cyclopentadienyl Ligands of Group 4 Precursors toward High-Temperature Atomic Layer Deposition

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Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications