Design and demonstration of very high-k (k&amp;#x223C;50) HfO&lt;inf&gt;2&lt;/inf&gt; for ultra-scaled Si CMOS

Migita, Shinji; Watanabe, Yoshio; Ota, Hiroyuki; Itô, Hiroshi; Kamimuta, Yuuichi; Nabatame, Toshihide; Toriumi, Akira

doi:10.1109/vlsit.2008.4588599

Cited by 36 publications

(48 citation statements)

References 3 publications

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“…40,47 The PMA treated film deposited on the hydroxyl terminated chemical oxide starting surface shows multiple strong reflections from the cubic HfO 2 phase indicating that the PMA step with TiN capping layer can act as an efficient metastable phase stabilization treatment consistent with previous reports on metal nitride capping layer anneal stabilization. [25][26][27] The importance of HfO 2 starting from an initial amorphous state prior to a cap anneal in order to obtain a cubic phase was also similarly reported by Toriumi and co-workers. 27 The 40 cycle HfO 2 layer deposited with the same process but on an H-terminated substrate (Si-H) shows a clear difference in the level of crystallinity as compared to the case of the chemical oxide starting surface.…”

Section: A Stacks With Tin Metal Gate-physical Analysismentioning

confidence: 75%

“…24 In this regard, recent studies have demonstrated stabilization of metastable phases of pure HfO 2 through the use of a Ti-containing overlayer followed by a PMA. [25][26][27][28][29][30] Triyoso et al utilized a 7 nm TiN capping layer followed by a 1000 C N 2 anneal to modify the microstructure of atomic layer deposited (ALD) HfO 2 from fully monoclinic, in the case of uncapped HfO 2 , to a mixture of monoclinic and non-monoclinic phases, for capped HfO 2 , and attributed the metastable phase formation to the constraint of volume expansion due to annealing as a result of mechanical constraint from the TiN overlayer. 25 Toriumi and co-workers have similarly reported the stabilization of the higher-k cubic phase for HfO 2 grown by rf-sputtering and subjected to a postgate electrode anneal.…”

Section: Introductionmentioning

confidence: 99%

“…25 Toriumi and co-workers have similarly reported the stabilization of the higher-k cubic phase for HfO 2 grown by rf-sputtering and subjected to a postgate electrode anneal. 26,27 One drawback that was pointed out was that the mechanism of gate-electrode induced compressive stress and concomitant oxygen vacancy formation, which helps stabilize the cubic phase, leads to a deleterious oxidation of the underlying Si when starting from a direct-contact (HF-last) Si substrate, thus limiting the ultimate k-value scaling using this approach. 27 In order to overcome this obstacle, Morita et al have investigated the inclusion of a sputter deposited Ti metal layer, with a high affinity for oxygen, as an oxygen-controlling layer in the gate electrode and subjected it to a postmetal anneal.…”

Section: Introductionmentioning

confidence: 99%

“…26,27 One drawback that was pointed out was that the mechanism of gate-electrode induced compressive stress and concomitant oxygen vacancy formation, which helps stabilize the cubic phase, leads to a deleterious oxidation of the underlying Si when starting from a direct-contact (HF-last) Si substrate, thus limiting the ultimate k-value scaling using this approach. 27 In order to overcome this obstacle, Morita et al have investigated the inclusion of a sputter deposited Ti metal layer, with a high affinity for oxygen, as an oxygen-controlling layer in the gate electrode and subjected it to a postmetal anneal. [28][29][30] In these studies, it was shown that with proper control of the Ti layer thickness and PMA conditions, deleterious oxidation of the Si substrate can be avoided while also stabilizing the higher-k cubic phase of HfO 2 .…”

Section: Introductionmentioning

confidence: 99%

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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

Consiglio¹,

Tapily²,

Clark³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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In this study, the authors examined the effects of different annealing schemes on crystallinity in atomic layer deposition (ALD) grown Ti-containing metal gates and ultrathin ALD HfO 2 high-k dielectric layers, and corresponding electrical results in metal oxide semiconductor capacitor (MOSCAP) devices. The authors investigated the effect of a postmetal deposition anneal (PMA) on the underlying HfO 2 , which was deposited using either a standard ALD process or a process which utilized a cyclical deposition and annealing scheme (termed DADA). The effect of the starting substrate surface, either chemically grown SiO 2 or H-terminated Si, on HfO 2 crystallinity was also studied. For 40 cycle ALD HfO 2 ($32 Å ) with a TiN overlayer, a transition from an amorphous state to a cubic phase was observed with the application of a PMA treatment. Evidence of the orthorhombic phase of HfO 2 with some level of texturing was observed for 40 cycle DADA processed films annealed with a TiN cap. Concomitantly a cubic (111) texture was observed for TiN deposited on DADA processed HfO 2 and subjected to a PMA. Suppression of crystallinity for HfO 2 deposited on H-terminated Si and annealed with a TiN layer was observed which illustrates the need for an adequate nucleation layer for uniform grain growth and increased atomic ordering. The authors also investigated metal gate stacks with a bilayer of TiN overlying Ti which showed reflections from both cubic TiN and hexagonal TiN 0.3 in the as-deposited state and after annealing clear evidence of silicidation (TiSi x ) was observed. In MOSCAP structures with 40 cycle ALD HfO 2 and a TiN overlayer subjected to a PMA, although the cubic phase of HfO 2 was stabilized, there was no associated improvement in device scaling. This study highlights the importance of the initial crystalline state and nucleation of HfO 2 as well as the thermal stability of the capping metal layer material when engineering dielectric layer crystallinity by means of a postmetal cap anneal. For ultrathin HfO 2 integrated in advanced metal oxide semiconductor structures, the benefits of the stabilization of a higher-k phase through postmetal gate anneal may not be fully realized due to increased leakage along grain boundaries or decrease in effective k due to changes in the lower-k interfacial layer.

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Section: A Stacks With Tin Metal Gate-physical Analysismentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Consiglio¹,

Tapily²,

Clark³

et al. 2014

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…4 They observed that amorphous Hf ͑1−x͒ Si x O 2 shows a value around 20; however, for monoclinic phase, the value is 15 and as they increased the temperature and changed the crystallization phase from monoclinic to tetragonal the value increased to 27. Moreover, Böscke et al 5 and Migita et al 6 obtained a of 36 and an even higher value for tetragonal and cubic HfO 2 , respectively. However the of amorphous hafniumbased oxides varies between 10 and 20.…”

mentioning

confidence: 92%

SmScO 3 thin films as an alternative gate dielectric

Özben

Lopes

Roeckerath

et al. 2008

Applied Physics Letters

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Samarium scandate thin films deposited on (100) Si have been investigated structurally and electrically. Rutherford backscattering spectrometry and transmission electron microscopy results show that the films are stoichiometric, amorphous, and smooth. X-ray diffraction analysis indicates that SmScO3 starts to crystallize at 900 °C. Capacitance and leakage current measurements reveal C-V curves with negligible hysteresis, a dielectric constant around 29 for 6 nm thick films, low leakage current densities in the range of 10−7 A/cm2, an effective oxide charge density of ∼5×1011 cm−2, and an interface trap density of 4.5×1011 (eV cm2)−1.

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