First-principles studies on metal induced gap states (MIGS) at metal/high-k HfO2 interfaces

Nakaoka, T.; Shiraishi, Koso; Akasaka, Y.; Chikyow, T.; Yamada, Kiyomi; Nara, Yasuo

doi:10.7567/ssdm.2005.a-9-3

Cited by 2 publications

(2 citation statements)

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“…In order to clarify the MIGS at metal/HfO 2 interfaces, we have performed the first principles calculations (24). The calculations are based on generalized gradient approximation (25), and ultrasoft pseudopotentials (26,27).…”

Section: Electronic Structures Of Metal Gates/hfo 2 Interfacesmentioning

confidence: 99%

Theoretical Studies on the Physical Properties of Poly-Si and Metal Gates/HfO2 Related High-k Dielectrics Interfaces

et al. 2006

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We have theoretically investigated poly-Si and metal gates on Hf-related high-k gate dielectrics. First, we have investigated the cause of the substantial threshold voltage (V th ) shifts observed in Hf-related high-k gate stacks with p+poly-Si gates. The oxygen vacancy (Vo) level in ionic HfO 2 is located in a relatively higher part of the band gap. If the p+poly-Si-gate is in contact with HfO 2 , Vo formation in the HfO 2 induces a subsequent electron transfer across the interface because of the higher energy level position of Vo, causing a substantial V th shifts in p+poly-Si gate MISFETs. Next, we also investigate the microscopic electronic structures at metal gates/HfO 2 interfaces. We have found that the wave functions of metal induced gap states (MIGS) have large amplitudes both around Hf and O atoms, which may be the cause of unusual work function behaviors of p-like metals.

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Section: Electronic Structures Of Metal Gates/hfo 2 Interfacesmentioning

confidence: 99%

Theoretical Studies on the Physical Properties of Poly-Si and Metal Gates/HfO2 Related High-k Dielectrics Interfaces

et al. 2006

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“…This delocalized feature of the Hf 5d orbital is the cause of its large hybridization with metal wave functions. As discussed above, the MIGS at the metal/HfO 2 interface penetrate very slightly into the HfO 2 region, and Hf 5d orbital can strongly hybridize with the metals due to its delocalized features [21].…”

Section: A New Concept Of the Generalized Charge Neutrality Levelmentioning

confidence: 91%

New Theory of Effective Workfunctions at Metal/High-k Dielectric Interfaces -Application to Metal/High-k HfO2 and La2O3 Dielectric Interfaces

Shiraishi

Nakayama

Akasaka³

et al. 2006

ECS Trans.

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We have constructed a universal theory of the work functions at metal/high-k HfO 2 and La 2 O 3 dielectric interfaces by introducing a new concept of generalized charge neutrality levels. Our theory systematically reproduces the experimentally observed work functions of various gate metals on Hf-based high-k dielectrics, including the hitherto unpredictable behaviors of the work functions of p-metals. Our new concept provides effective guiding principles to achieving near-bandedge work functions of gate metals. Moreover, we discuss the potential of the new high-k dielectrics of La 2 O 3 based on this new concept.

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First-principles studies on metal induced gap states (MIGS) at metal/high-k HfO2 interfaces

Cited by 2 publications

References 0 publications

Theoretical Studies on the Physical Properties of Poly-Si and Metal Gates/HfO2 Related High-k Dielectrics Interfaces

Theoretical Studies on the Physical Properties of Poly-Si and Metal Gates/HfO2 Related High-k Dielectrics Interfaces

New Theory of Effective Workfunctions at Metal/High-k Dielectric Interfaces -Application to Metal/High-k HfO2 and La2O3 Dielectric Interfaces

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