Hafnium(IV) oxide

Last updated
Hafnium(IV) oxide
Hafnium(IV) oxide structure Kristallstruktur Zirconium(IV)-oxid.png
Hafnium(IV) oxide structure
Hafnium(IV) oxide Hafnium(IV) oxide.jpg
Hafnium(IV) oxide
Names
IUPAC name
Hafnium(IV) oxide
Other names
Hafnium dioxide
Hafnia
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.031.818 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 235-013-2
PubChem CID
UNII
  • InChI=1S/Hf.2O Yes check.svgY
    Key: CJNBYAVZURUTKZ-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/Hf.2O/rHfO2/c2-1-3
    Key: CJNBYAVZURUTKZ-MSHMTBKAAI
  • O=[Hf]=O
Properties
HfO2
Molar mass 210.49 g/mol
Appearanceoff-white powder
Density 9.68 g/cm3, solid
Melting point 2,758 °C (4,996 °F; 3,031 K)
Boiling point 5,400 °C (9,750 °F; 5,670 K)
insoluble
−23.0·10−6 cm3/mol
Thermochemistry
–1117 kJ/mol [1]
Hazards
Flash point Non-flammable
Related compounds
Other cations
Titanium(IV) oxide
Zirconium(IV) oxide
Related compounds
 Hafnium nitride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Hafnium(IV) oxide is the inorganic compound with the formula HfO
2. Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. [2] Hafnium dioxide is an intermediate in some processes that yield hafnium metal.

Contents

Hafnium(IV) oxide is quite inert. It reacts with strong acids such as concentrated sulfuric acid and with strong bases. It dissolves slowly in hydrofluoric acid to give fluorohafnate anions. At elevated temperatures, it reacts with chlorine in the presence of graphite or carbon tetrachloride to give hafnium tetrachloride.

Structure

Hafnia typically adopts the same structure as zirconia (ZrO2). Unlike TiO2, which features six-coordinate Ti in all phases, zirconia and hafnia consist of seven-coordinate metal centres. A variety of other crystalline phases have been experimentally observed, including cubic fluorite (Fm3m), tetragonal (P42/nmc), monoclinic (P21/c) and orthorhombic (Pbca and Pnma). [3] It is also known that hafnia may adopt two other orthorhombic metastable phases (space group Pca21 and Pmn21) over a wide range of pressures and temperatures, [4] presumably being the sources of the ferroelectricity observed in thin films of hafnia. [5] A rhombohedral phase of hafnia also exists. [6] [7]

Thin films of hafnium oxides deposited by atomic layer deposition are usually crystalline. Because semiconductor devices benefit from having amorphous films present, researchers have alloyed hafnium oxide with aluminum or silicon (forming hafnium silicates), which have a higher crystallization temperature than hafnium oxide. [8]

Applications

Hafnia is used in optical coatings, and as a high-κ dielectric in DRAM capacitors and in advanced metal–oxide–semiconductor devices. Hafnium-based oxides were introduced by Intel in 2007 as a replacement for silicon oxide as a gate insulator in field-effect transistors. [9] The advantage for transistors is its high dielectric constant: the dielectric constant of HfO2 is 4–6 times higher than that of SiO2, which is 3.9. [10] The dielectric constant and other properties depend on the deposition method, composition and microstructure of the material.

Research

Hafnium oxide (as well as doped and oxygen-deficient hafnium oxide) attracts additional interest as a possible candidate for resistive-switching memories [11] and CMOS-compatible ferroelectric memories such as Ferroelectric field effect transistors (FeFET memory) [12] , Ferroelectric Rams (FeRAM) and Ferroelectric tunnel junction (FTJ) [12] as well as memory chips. [13] [14] [15] [16]

As silicon technology approached its scaling limit, ferroelectric hafnia is seen as one of the potential replacements for CMOS and beyond-CMOS devices for current and future electronics [17] [18] [19] . It has the potential to enhance the design of electronic devices and challenge the traditional von Neumann computing paradigm by enabling near-memory computing [20] , which allows for higher speed and lower power consumption in energy-efficient non-volatile memories, neuromorphic devices [21] [22] , and AI applications [23] [24] . Beyond computing, its ferroelectric, dielectric, and pyroelectric properties are also being studied for applications in sensors and other emerging technologies [24] [25] [26] .

Because of its very high melting point, hafnia is also used as a refractory material in the insulation of such devices as thermocouples, where it can operate at temperatures up to 2500°C. [27]

Multilayered films of hafnium dioxide, silica, and other materials have been developed for use in passive cooling of buildings. The films reflect sunlight and radiate heat at wavelengths that pass through Earth's atmosphere, and can have temperatures several degrees cooler than surrounding materials under the same conditions. [28]

Challenges

HfO₂-based ferroelectrics face several challenges across materials, devices, integration, and applications [21] [29] . On the material side, difficulties include stabilizing the metastable orthorhombic phase and controlling oxygen vacancy concentration, while research opportunities focus on controlled doping strategies, superlattice engineering, strain/interface engineering, and exploring novel lead-free systems [30] [31] [32] .

At the device level, issues such as wake-up and fatigue effects, endurance limits under full switching, scaling below 10 nm, and charge-trapping in FeFETs hinder reliability, but approaches like domain engineering, low-voltage partial switching, advanced 3D device architectures, and interface dielectrics offer promising solutions [30] [29] . In terms of integration, BEOL compatibility, wafer-scale uniformity, interfacial degradation, and process variability remain major obstacles, yet ALD-based deposition, interface control for oxygen vacancy management, and stacked or multilayer designs for 3D memory integration are promising paths forward [17] [33] [34] . Finally, for applications, limitations include NVM endurance, thermal drift, and CIM-related static power and accuracy losses, but future opportunities lie in asymmetric programming, superlattice capacitors, cryogenic-optimized memory, ferroelectric CIM, FeCAP-based systems, and neuromorphic or reservoir computing architectures [21] [34] [35] .

References

  1. ↑ Kornilov, A.N.; Ushakova, I.M.; Huber, E.J.; Holley, C.E. (1975). "The enthalpy of formation of hafnium dioxide". The Journal of Chemical Thermodynamics. 7 (1): 21–26. Bibcode:1975JChTh...7...21K. doi:10.1016/0021-9614(75)90076-2.
  2. ↑ Bersch, Eric; et al. (2008). "Band offsets of ultrathin high-k oxide films with Si". Phys. Rev. B. 78 (8): 085114. Bibcode:2008PhRvB..78h5114B. doi:10.1103/PhysRevB.78.085114.
  3. ↑ V. Miikkulainen; et al. (2013). "Crystallinity of inorganic films grown by atomic layer deposition: Overview and general trends". Journal of Applied Physics . 113 (2) 021301. Table III. Bibcode:2013JAP...113b1301M. doi:10.1063/1.4757907.
  4. ↑ T. D. Huan; V. Sharma; G. A. Rossetti, Jr.; R. Ramprasad (2014). "Pathways towards ferroelectricity in hafnia". Physical Review B . 90 (6): 064111. arXiv: 1407.1008 . Bibcode:2014PhRvB..90f4111H. doi:10.1103/PhysRevB.90.064111. S2CID   53347579.
  5. ↑ T. S. Boscke (2011). "Ferroelectricity in hafnium oxide thin films". Applied Physics Letters . 99 (10) 102903. Bibcode:2011ApPhL..99j2903B. doi:10.1063/1.3634052.
  6. ↑ Wei, Yingfen; Nukala, Pavan; Salverda, Mart; Matzen, Sylvia; Zhao, Hong Jian; Momand, Jamo; Everhardt, Arnoud S.; Agnus, Guillaume; Blake, Graeme R.; Lecoeur, Philippe; Kooi, Bart J.; Íñiguez, Jorge; Dkhil, Brahim; Noheda, Beatriz (2018-10-22). "A rhombohedral ferroelectric phase in epitaxially strained Hf0.5Zr0.5O2 thin films". Nature Materials. 17 (12): 1095–1100. arXiv: 1801.09008 . doi:10.1038/s41563-018-0196-0. ISSN   1476-4660. PMID   30349031.
  7. ↑ Ouyang, Wenbin; Jia, Fanhao; Liu, Chang; Cheng, Xuli; Meng, Yaping; Gao, Ruiling; Picozzi, Silvia; Ren, Wei (2023-11-21). "Structural stability and polarization analysis of rhombohedral phases of HfO2" . Applied Physics Letters. 123 (21): 212902. doi:10.1063/5.0169911. ISSN   0003-6951.
  8. ↑ J.H. Choi; et al. (2011). "Development of hafnium based high-k materials—A review". Materials Science and Engineering: R. 72 (6): 97–136. doi:10.1016/j.mser.2010.12.001.
  9. ↑ Intel (11 November 2007). "Intel's Fundamental Advance in Transistor Design Extends Moore's Law, Computing Performance".
  10. ↑ G. D. Wilk; R. M. Wallace; J. M. Anthony (2001). "High-κ gate dielectrics: Current status and materials properties considerations". Journal of Applied Physics. 89 (10): 5243–5275. Bibcode:2001JAP....89.5243W. doi:10.1063/1.1361065., Table 1
  11. ↑ K.-L. Lin; et al. (2011). "Electrode dependence of filament formation in HfO2 resistive-switching memory". Journal of Applied Physics . 109 (8) 084104: 084104–084104–7. Bibcode:2011JAP...109h4104L. doi:10.1063/1.3567915.
  12. 1 2 Koo, Ryun-Han; Shin, Wonjun; Kim, Jangsaeng; Yim, Jiyong; Ko, Jonghyun; Jung, Gyuweon; Im, Jiseong; Park, Sung-Ho; Kim, Jae-Joon; Cheema, Suraj S; Kwon, Daewoong; Lee, Jong-Ho (2024). "Polarization Pruning: Reliability Enhancement of Hafnia-Based Ferroelectric Devices for Memory and Neuromorphic Computing". Advanced Science. 11 (43): 2407729. Bibcode:2024AdvSc..1107729K. doi:10.1002/advs.202407729. ISSN   2198-3844. PMC   11578341 . PMID   39324607.
  13. ↑ Imec (7 June 2017). "Imec demonstrates breakthrough in CMOS-compatible Ferroelectric Memory".
  14. ↑ The Ferroelectric Memory Company (8 June 2017). "World's first FeFET-based 3D NAND demonstration". Archived from the original on 1 September 2017. Retrieved 30 July 2017.
  15. ↑ T. S. Böscke; J. Müller; D. Bräuhaus (7 Dec 2011). "Ferroelectricity in hafnium oxide: CMOS compatible ferroelectric field effect transistors". 2011 International Electron Devices Meeting. IEEE. pp. 24.5.1–24.5.4. doi:10.1109/IEDM.2011.6131606. ISBN   978-1-4577-0505-2.
  16. ↑ Nivole Ahner (August 2018). Mit HFO2 voll CMOS-kompatibel (in German). Elektronik Industrie.
  17. 1 2 "Future Prospective Beyond-CMOS Technology : From Silicon-Based Devices to Alternate Devices". Taylor & Francis. 2023-12-22. doi:10.1201/9781003393542-1. Archived from the original on 2025-05-03.
  18. ↑ Evans, Donald M. (2023-08-02). "Next generation information storage using hafnia-based ferroelectrics: Back to the future?". Matter. 6 (8): 2586–2589. doi:10.1016/j.matt.2023.06.031. ISSN   2590-2393.
  19. ↑ 2020 10th Institute of Electrical and Electronics Engineers International Conference on Cyber Technology in Automation, Control, and Intelligent Systems (CYBER). IEEE. 2020. doi:10.1109/cyber50695.2020. ISBN   978-1-7281-9010-5.
  20. ↑ Li, Zhenhai; Wang, Tianyu; Yu, Jiajie; Meng, Jialin; Liu, Yongkai; Zhu, Hao; Sun, Qingqing; Zhang, David Wei; Chen, Lin (2022). "Ferroelectric Hafnium Oxide Films for In-Memory Computing Applications". Advanced Electronic Materials. 8 (12): 2200951. doi: 10.1002/aelm.202200951 . ISSN   2199-160X.
  21. 1 2 3 Yu, Xiao; Zhong, Ni; Cheng, Yan; Xin, Tianjiao; Luo, Qing; Gong, Tiancheng; Chen, Jiezhi; Wu, Jixuan; Cheng, Ran; Fu, Zhiyuan; Tang, Kechao; Luo, Jin; Ren, Tianling; Xue, Fei; Chen, Lin (2025-05-26). "Ferroelectric materials, devices, and chips technologies for advanced computing and memory applications: development and challenges". Science China Information Sciences. 68 (6): 160401. doi:10.1007/s11432-025-4432-x. ISSN   1869-1919.
  22. ↑ Evans, Donald M. (2023-08-02). "Next generation information storage using hafnia-based ferroelectrics: Back to the future?". Matter. 6 (8): 2586–2589. doi:10.1016/j.matt.2023.06.031. ISSN   2590-2393.
  23. ↑ Yan, Shaoan; Xu, Pei; Li, Gang; Li, Yuchun; Zhu, Yingfang; Zhu, Xiaona; Yang, Qiong; Li, Meng; Tang, Minghua; Lu, Hongliang; Liu, Sen; Li, Qingjiang; Zhang, David Wei; Chen, Zhigang (2025-01-05). "Artificial intelligence-driven phase stability evaluation and new dopants identification of hafnium oxide-based ferroelectric materials". npj Computational Materials. 11 (1): 2. Bibcode:2025npjCM..11....2Y. doi:10.1038/s41524-024-01510-4. ISSN   2057-3960.
  24. 1 2 Lederer, M.; Kämpfe, T. (2025-03-31). "Synaptic devices based on ferroelectric hafnium oxide: Recent advances, challenges, and future perspectives". Applied Physics Letters. 126 (13): 130503. Bibcode:2025ApPhL.126m0503L. doi:10.1063/5.0254762. ISSN   0003-6951.
  25. ↑ Lee, Youngseo; Kim, Sungjun (2025-07-16). "Enhanced synaptic performance in hafnia-based ferroelectric memristors with MIFS structure for neuromorphic computing". Ceramics International. doi:10.1016/j.ceramint.2025.07.213. ISSN   0272-8842.
  26. ↑ Bi, Jinshun; Faizan, Muhammad; Liu, Xuefei; Ma, Yue; Wang, Xu; Stempitsky, Viktor (2025-06-01). "Ferroelectric devices for artificial intelligence chips". Chip. 4 (2): 100129. doi:10.1016/j.chip.2025.100129. ISSN   2709-4723.
  27. ↑ Very High Temperature Exotic Thermocouple Probes product data, Omega Engineering, Inc., retrieved 2008-12-03
  28. ↑ "Aaswath Raman | Innovators Under 35 | MIT Technology Review". August 2015. Retrieved 2015-09-02.
  29. 1 2 Han, Dong In; Choi, Hyojun; Lee, Dong Hyun; Kim, Se Hyun; Lee, Jaewook; Jeon, Intak; Jung, Chang Hwa; Lim, Hanjin; Park, Min Hyuk (2025). "Strategies for Reducing Operating Voltage of Ferroelectric Hafnia by Decreasing Coercive Field and Film Thickness". Advanced Physics Research. 4 (6): 2400194. doi:10.1002/apxr.202400194. ISSN   2751-1200.
  30. 1 2 Silva, J. P. B.; Sekhar, K. C.; Negrea, R. F.; MacManus-Driscoll, J. L.; Pintilie, L. (2022-03-01). "Progress and perspective on different strategies to achieve wake-up-free ferroelectric hafnia and zirconia-based thin films". Applied Materials Today. 26 101394. doi:10.1016/j.apmt.2022.101394. ISSN   2352-9407.
  31. ↑ Li, Gang; Yan, Shaoan; Liu, Yulin; Zhang, Wanli; Xiao, Yongguang; Yang, Qiong; Tang, Minghua; Li, Jiangyu; Long, Zhilin (2025-02-15). "Unraveling the origins of ferroelectricity in doped hafnia through carrier-mediated phase transitions". npj Computational Materials. 11 (1): 34. Bibcode:2025npjCM..11...34L. doi:10.1038/s41524-025-01515-7. ISSN   2057-3960.
  32. ↑ Mukherjee, Binayak; Fedorova, Natalya S.; Íñiguez-González, Jorge (2024-07-16). "First-principles predictions of HfO2-based ferroelectric superlattices". npj Computational Materials. 10 (1) 153. doi:10.1038/s41524-024-01344-0. ISSN   2057-3960.
  33. ↑ Majumdar, Sayani (2022). "Back-End CMOS Compatible and Flexible Ferroelectric Memories for Neuromorphic Computing and Adaptive Sensing". Advanced Intelligent Systems. 4 (4) 2100175. doi:10.1002/aisy.202100175. ISSN   2640-4567.
  34. 1 2 Liao, Jiajia; Dai, Siwei; Peng, Ren-Ci; Yang, Jiangheng; Zeng, Binjian; Liao, Min; Zhou, Yichun (2023-05-01). "HfO2-based ferroelectric thin film and memory device applications in the post-Moore era: A review". Fundamental Research. 3 (3): 332–345. doi:10.1016/j.fmre.2023.02.010. ISSN   2667-3258. PMC   11197553 . PMID   38933762.
  35. ↑ Ueda, Akiko; Akinaga, Hiroyuki; Agarwal, Sapan; Hagmann, Joseph A; Das, Shamik; Marinella, Matthew J; Chen, An (2025-04-07). "Green materials in semiconductors: perspective from the IRDS beyond-CMOS roadmap". Nanotechnology. 36 (14): 142001. Bibcode:2025Nanot..36n2001U. doi:10.1088/1361-6528/adb041. ISSN   0957-4484.
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