Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

Hinkle, Christopher L.; Galatage, Rohit; Chapman, R. A.; Vogel, Eric M.; Alshareef, Husam N.; Freeman, C. M.; Christensen, Mikael; Wimmer, E.; Niimi, H.; Li-Fatou, A.; Shaw, J. B.; Chambers, James J.

doi:10.1063/1.3701165

Cited by 15 publications

(5 citation statements)

References 13 publications

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“…There have been a few preliminary theoretical 34 and experimental 40,41 investigations of EWF modulation in the recent past. We have carried out a systematic analysis of the EWF modulation through changes in the stoichiometry at the HfO 2 /TiN interface.…”

Section: Effective Work Function Engineeringmentioning

confidence: 99%

Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Pandey¹,

Sathiyanarayanan²,

Kwon³

et al. 2013

Journal of Applied Physics

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We investigate the physical properties of a portion of the gate stack of an ultra-scaled complementary metal-oxide-semiconductor (CMOS) device. The effects of point defects, such as oxygen vacancy, oxygen, and aluminum interstitials at the HfO2/TiN interface, on the effective work function of TiN are explored using density functional theory. We compute the diffusion barriers of such point defects in the bulk TiN and across the HfO2/TiN interface. Diffusion of these point defects across the HfO2/TiN interface occurs during the device integration process. This results in variation of the effective work function and hence in the threshold voltage variation in the devices. Further, we simulate the effects of varying the HfO2/TiN interface stoichiometry on the effective work function modulation in these extremely-scaled CMOS devices. Our results show that the interface rich in nitrogen gives higher effective work function, whereas the interface rich in titanium gives lower effective work function, compared to a stoichiometric HfO2/TiN interface. This theoretical prediction is confirmed by the experiment, demonstrating over 700 meV modulation in the effective work function.

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Section: Effective Work Function Engineeringmentioning

confidence: 99%

Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Pandey¹,

Sathiyanarayanan²,

Kwon³

et al. 2013

Journal of Applied Physics

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“…While the EWF of atomic layer deposition (ALD)-grown stoichiometric TiN ranges from 4.7 to 4.9 eV, relevant for low V th in p-channel MIS transistor, doping of TiN with low WF metal, e.g., Al, results in lower EWF values in the range 4.1–4.4 eV. − Another option is provided by exposure of TiN to nitrogen plasma, which points toward significant impact of the metal stoichiometry. , However, there is an additional factor affecting stoichiometry of TiN at interfaces with oxide insulators: the oxygen “scavenging” from the underlying oxide leads to oxidation of the PVD-grown TiN films on SiO 2 and Al 2 O 3 . , …”

Section: Introductionmentioning

confidence: 99%

Mechanisms of TiN Effective Workfunction Tuning at Interfaces with HfO₂ and SiO₂

et al. 2020

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Using combination of electrical measurements and internal photoemission interface barrier characterization the effective workfunction (EWF) changes of nm-thin TiN layer deposited on top of oxide insulators (SiO2, HfO2) have been correlated with atomic and chemical composition of the metal/oxide interfaces characterized by photoelectron spectroscopy and X-ray absorption.The major mechanisms of the EWF tuning are shown to be correlated to re-distribution of light N and O atoms. Oxygen scavenging from the underlying changes the TiN EWF by forming Ti oxynitride layer at the interface and introducing charge traps in the near-interface oxide layer.By contrast, significant (≈1 eV) reduction of EWF ban be achieved by introduction of a thin TiAl getter layer on top of TiN film. The mechanism of this reduction can be traced down to formation of metallic Ti caused by nitrogen scavenging by TiAl as evidenced by AlN formation.

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“…Solutions for the nMOS EWF in the range of 4.1-4.4 eV can be obtained by doping the TiN film with different materials (such as Al and N). [8][9][10] Literature reports had shown that the addition of Al ions into TiN layer can significantly change the TiN EWF. 8,10 The metal gate EWF shift is related to formation of different dipoles at the interface between metal gate and high-k due Al diffusion.…”

Section: Introductionmentioning

confidence: 99%

Metal gate work function tuning by Al incorporation in TiN

Lima

Dekkers

Lisoni

et al. 2014

Journal of Applied Physics

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Articles you may be interested inDetermining factor of effective work function in metal/bi-layer high-k gate stack structure studied by photoemission spectroscopy Appl. Phys. Lett. 100, 112906 (2012); 10.1063/1.3695166 Photoinduced charge-trapping phenomena in metal/high-k gate stack structures studied by synchrotron radiation photoemission spectroscopy Appl. Phys. Lett. 96, 162902 (2010); 10.1063/1.3409162 Thermally stable high effective work function TaCN thin films for metal gate electrode applications Titanium nitride (TiN) films have been used as gate electrode on metal-oxide-semiconductor (MOS) devices. TiN effective work function (EWF) values have been often reported as suitable for pMOS. For nMOS devices, a gate electrode with sufficient low EWF value with a similar robustness as TiN is a challenge. Thus, in this work, aluminum (Al) is incorporated into the TiN layer to reduce the EWF values, which allows the use of this electrode in nMOS devices. Titanium aluminum (TiAl), Al, and aluminum nitride (AlN) layers were introduced between the high-k (HfO 2 ) dielectric and TiN electrode as Al diffusion sources. Pt/TiN (with Al diffusion) and Pt/TiN/TiAl/TiN structures were obtained and TiN EWF values were reduced of 0.37 eV and 1.09 eV, respectively. The study of TiN/AlN/HfO 2 /SiO 2 /Si/Al structures demonstrated that AlN layer can be used as an alternative film for TiN EWF tuning. A decrease of 0.26 eV and 0.45 eV on TiN EWF values were extracted from AlN/TiN stack and AlN/TiN laminate stack, respectively. AlN/TiN laminate structures have been shown to be more effective to reduce the TiN work function than just increasing the AlN thickness. V C 2014 AIP Publishing LLC.

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Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

Abstract: Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition KAUST Repository

Cited by 15 publications

References 13 publications

Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Mechanisms of TiN Effective Workfunction Tuning at Interfaces with HfO₂ and SiO₂

Metal gate work function tuning by Al incorporation in TiN

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Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

Abstract: Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition KAUST Repository

Cited by 15 publications

References 13 publications

Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Role of point defects and HfO2/TiN interface stoichiometry on effective work function modulation in ultra-scaled complementary metal–oxide–semiconductor devices

Mechanisms of TiN Effective Workfunction Tuning at Interfaces with HfO2 and SiO2

Metal gate work function tuning by Al incorporation in TiN

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Mechanisms of TiN Effective Workfunction Tuning at Interfaces with HfO₂ and SiO₂