Microstructure and electrical properties of thin HfO2 deposited by plasma-enhanced atomic layer deposition
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The influence of annealing in the temperature range of 150–300 °C during plasma-enhanced atomic layer deposition of HfO2 and the conditions of the following thermal processing on microstructure and electrical properties have been studied. The microstructure was examined by transmission electron microscopy and electron diffraction. The as-deposited HfO2 film consists of monoclinic crystallites embedded in an amorphous matrix. It was found that the crystallite density grows with the increase in the deposition temperature; however, the size of the crystallites does not change. Subsequent annealing at 425 °C for 30 min or at 950 °C for 4 s led to complete crystallization through the lateral growth of the crystallites of samples formed at 250 and 300 °C. However, for the sample formed at 150 °C, subsequent annealing at 425 °C resulted in the formation of dendritic-like crystalline clusters embedded in an amorphous matrix. The leakage currents in polycrystalline and even amorphous HfO2 films after the annealing were drastically increased. That could be explained by crystallization after the annealing. However, the C impurity redistribution and the growth of an interfacial layer could also affect the leakage.
Investigation was supported by Government Program of FASO Russia “Theoretical and experimental researches on advanced integrated devices for nanoelectronics, MEMS, and NEMS”. The experimental part of this work was partially performed on the equipment of the Resource Center of Probe and Electron Microscopy (Kurchatov Complex of NBICS-Technologies, NRC “Kurchatov Institute”).
- 2.Consiglio S, Tapily K, Clark RD, Hasegawa T, Amano F, Leusink GJ (2014) Engineering crystallinity of atomic layer deposited gate stacks containing ultrathin HfO2 and a Ti-based metal gate: effects of postmetal gate anneal and integration schemes. J Vac Sci Technol B B32:03D122-1–03D122-12Google Scholar
- 3.Zhao X, Vanderbilt D (2002) First-principles study of structural, vibrational, and lattice dielectric properties of hafnium oxide. Phys Rev B 65:233106-1–233106-4Google Scholar
- 17.Choi M, Lyons JL, Janotti A, Van de Walle CG (2013) Impact of carbon and nitrogen impurities in high-j dielectrics on metal-oxide-semiconductor devices. Appl Phys Lett 102:142902-1–142902-4Google Scholar
- 19.Fujiia S, Miyata N, Migita S, Horikawa T, Toriumi A (2005) Nanometer-scale crystallization of thin HfO2 films studied by HF-chemical etching. Appl Phys Lett 86:212907-1–212907-3Google Scholar
- 22.Kim J, Kim S, Kang H, Choi J, Jeon H, Cho M, Chung K, Back S, Yoo K, Bae C (2005) Composition, structure, and electrical characteristics of HfO2 gate dielectrics grown using the remote- and direct-plasma atomic layer deposition methods. J Appl Phys 98:094504-1–094504-7Google Scholar