Low temperature formation of higher-<i>k</i> cubic phase HfO2 by atomic layer deposition on GeOx/Ge structures fabricated by <i>in-situ</i> thermal oxidation

Zhang, Rui; Huang, Po-Chin; Taoka, Noriyuki; Yokoyama, Masafumi; Takenaka, Mitsuru; Takagi, Shinichi

doi:10.1063/1.4941538

Cited by 6 publications

(3 citation statements)

References 17 publications

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“…The M-atoms (M ¼ Hf, Zr) in the tetragonal structure of MO 2 is surrounded by 8 oxygen atoms, 4 of which are at a shorter distance. 35 Thus, replacement of some of the M-atoms by Ge-atoms of smaller ionic radius 28 can proceed with minimal lattice distortion, eventually forming a Ge-stabilized tetragonal structure at the IL which could act as a template 34 for subsequent bottom-up crystallization 17 of the 100 ALD cycle Hf 1Àx Zr x O 2 films, thus explaining the requirement for a smaller amount of ZrO 2 for films grown on Ge by the DADA ALD process. XPS measured binding energy differences of the Zr 4þ 3 d core electrons support the maximum entropy ARXPS compositional depth profiling which indicates that the IL mostly consists of a network of M-O-Ge type bonds compared to the M-O-M type bonding arrangement in the bulk of the dielectric film.…”

Section: Discussionmentioning

confidence: 99%

Role of Ge and Si substrates in higher-k tetragonal phase formation and interfacial properties in cyclical atomic layer deposition-anneal Hf1−xZrxO2/Al2O3 thin film stacks

Dey

Tapily²,

Consiglio³

et al. 2016

Journal of Applied Physics

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Using a five-step atomic layer deposition (ALD)-anneal (DADA) process, with 20 ALD cycles of metalorganic precursors followed by 40 s of rapid thermal annealing at 1073 K, we have developed highly crystalline Hf 1Àx Zr x O 2 (0 x 1) thin films (<7 nm) on $1 nm ALD Al 2 O 3 passivated Ge and Si substrates for applications in higher-k dielectric metal oxide semiconductor field effect transistors below 10 nm technology node. By applying synchrotron grazing incidence x-ray d-spacing maps, x-ray photoelectron spectroscopy (XPS), and angle-resolved XPS, we have identified a monoclinic to tetragonal phase transition with increasing ZrO 2 content, elucidated the role of the Ge vs Si substrates in complete tetragonal phase formation (CTPF), and determined the interfacial characteristics of these technologically relevant films. The ZrO 2 concentration required for CTPF is lower on Ge than on Si substrates (x $ 0.5 vs. x $ 0.86), which we attribute as arising from the growth of an ultra-thin layer of metal germanates between the Hf 1Àx Zr x O 2 and Al 2 O 3 /Ge, possibly during the first deposition and annealing cycle. Due to Ge-induced tetragonal phase stabilization, the interfacial metal germanates could act as a template for the subsequent preferential growth of the tetragonal Hf 1Àx Zr x O 2 phase following bottom-up crystallization during the DADA ALD process. We surmise that the interfacial metal germanate layer also function as a diffusion barrier limiting excessive Ge uptake into the dielectric film. An ALD Al 2 O 3 passivation layer of thickness !1.5 nm is required to minimize Ge diffusion for developing highly conformal and textured HfO 2 based higher-k dielectrics on Ge substrates using the DADA ALD process. Published by AIP Publishing.

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Section: Discussionmentioning

confidence: 99%

Role of Ge and Si substrates in higher-k tetragonal phase formation and interfacial properties in cyclical atomic layer deposition-anneal Hf1−xZrxO2/Al2O3 thin film stacks

Dey

Tapily²,

Consiglio³

et al. 2016

Journal of Applied Physics

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“…In recent years, foldable silicon and/or integrated circuits with a 1D nanostructure have progressed greatly both in terms of assembly strategy and functional system construction [4][5][6][7][8]. Compared to silicon, germanium (Ge) is well accepted as an ideal alternative to silicon for next-generation complementary metal oxide semiconductor (CMOS) devices due to its small bandgap (0.68 eV) and high carrier mobility (about twice the amount for electrons and four times the amount for holes) [9,10]. However, although Ge CMOS technology has attracted sustained research interest for scaling beyond the Si CMOS limitation, Ge-based flexible electronics are rarely discussed.…”

Section: Introductionmentioning

confidence: 99%

Solution-processed high-k dielectrics for improving the performance of flexible intrinsic Ge nanowire transistors: dielectrics screening, interface engineering and electrical properties

Lou¹,

Zhang²,

Xie³

et al. 2019

J. Phys. D: Appl. Phys.

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Although Ge-based CMOS have attracted sustained research interest for scaling beyond the Si CMOS limitation, Ge-based flexible electronics are still rarely discussed. For Ge-based flexible electronics, seeking proper dielectrics-both with excellent dielectric/Ge interface quality and special temperature compatibility with the polymer supports in the manufacturing process-is still the main challenge. In addition, focusing on solution-processed high-k dielectrics instead of vacuum fabrication technology is a particular concern. Here, we report on our systematic efforts to improve the device performance of flexible intrinsic Ge nanowire transistors on a polyimide substrate with solution-processed high-k dielectric films. Firstly, YO x thin film was determined to be the most suitable candidate among various solution-processed high-k dielectrics (ZrO x , HfO x , TiO x , AlO x , YO x and LaO x ) due to its most promising electrical properties, surface roughness and process temperature. Secondly, the excellent YO x /Ge interface quality was successfully achieved under optimized conditions with a precursor solution concentration of 0.2 M, an annealing temperature of 500 °C and an O 2 annealing atmosphere. Ultimately, benefitting from proper dielectric screening and interface engineering, single intrinsic flexible Ge nanowire transistors were demonstrated, exhibiting excellent operating characteristics comparable to devices on rigid substrates. The devices further show good stability, implying their great potential in flexible electronics.

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“…In addition, much literature has mentioned the mixing issue between HfO 2 and GeO 2 , leading to deteriorated electrical properties. 11,12 The main reason for this is the vaporization of GeO, which diffuses into the HfO 2 oxidation layer, causing an increase in interfacial defects and altering the chemical properties of HfO 2 . Therefore, if the deposition process of the GeO 2 layer is modified to strengthen or improve the bonding capability in the interfacial layer, it will effectively reduce the phenomenon of GeO vaporization.…”

mentioning

confidence: 99%

Atom-Scaled Hafnium Doping for Strengthening the Germanium Oxide Interfacial Layer of The Gate Stack of Germanium P-Type Metal-Oxide-Semiconductor Field Effect Transistor

Li,

Chen,

Lin

et al. 2024

ECS J. Solid State Sci. Technol.

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We have developed a method that uses a half-cycle Hf precursor adsorption to subtly dope GeO2 IL of the Hf-based gate stack through in situ plasma-enhanced atomic layer deposition. This technique can effectively reduce GeO vaporization and improve the thermal stability of the GeO2 layer. Our results indicated that the accumulation capacitance (Cacc) undergoing higher temperatures showed no noticeable increase in the capacitance-voltage (CV) curves once Hf was delicately introduced into the GeO2 layer. According to the Ge 3d spectra of X-ray photoelectron spectroscopy, we found that the IL had a signal from extra Hf-O bonds; thus, we conclude GeO evaporation can be suppressed substantially by Hf incorporation. As a result, adding metal into GeOx IL to form HfGeOx achieved a remarkably low leakage current of 9 × 10-5 A/cm2 and the lowest interface trap density (Dit) of approximately 2 × 1011 eV−1 cm−2 at 500C of PMA. In addition, applying this gate stack structure to device fabrication significantly reduced the leakage current of the off-state and improved the effective peak hole mobility.

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Low temperature formation of higher-k cubic phase HfO2 by atomic layer deposition on GeOx/Ge structures fabricated by in-situ thermal oxidation

Cited by 6 publications

References 17 publications

Role of Ge and Si substrates in higher-k tetragonal phase formation and interfacial properties in cyclical atomic layer deposition-anneal Hf1−xZrxO2/Al2O3 thin film stacks

Role of Ge and Si substrates in higher-k tetragonal phase formation and interfacial properties in cyclical atomic layer deposition-anneal Hf1−xZrxO2/Al2O3 thin film stacks

Solution-processed high-k dielectrics for improving the performance of flexible intrinsic Ge nanowire transistors: dielectrics screening, interface engineering and electrical properties

Atom-Scaled Hafnium Doping for Strengthening the Germanium Oxide Interfacial Layer of The Gate Stack of Germanium P-Type Metal-Oxide-Semiconductor Field Effect Transistor

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