Systematic study on work-function-shift in metal/Hf-based high-k gate stacks

Kita, Yusuke; Yoshida, Shigeaki; Hosoi, Takuji; Shimura, Takayoshi; Shiraishi, Kenji; Nara, Yasuo; Yamada, Keiichi; Watanabe, Heiji

doi:10.1063/1.3103314

Cited by 9 publications

(4 citation statements)

References 6 publications

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“…This discrepancy can be explained by positive charges not on the surface of GeO 2 but in GeO 2 close to the GeO 2 /Ge interface. One typical situation for this is the dipole formation 29 of positive charges in GeO 2 with emitted electrons in the Ge bulk at the GeO 2 /Ge interface. Now that we have proposed that positive charges, originating from water-related species, are generated in GeO 2 close to the GeO 2 /Ge interface at low RHs of up to ∼1%, the next step is to provide evidence of water-related species existing at the interface.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Water Growth on GeO₂/Ge(100) Stack and Its Effect on the Electronic Properties of GeO₂

Mura¹,

Hideshima²,

Liu

et al. 2012

J. Phys. Chem. C

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Water growth on GeO2 films on a Ge(100) substrate and their effect on the electronic properties of GeO2 films are investigated using ambient-pressure X-ray photoelectron spectroscopy at relative humidity (RH) values from 0% to approximately 45%. Water adsorbs at low RHs and continues to grow gradually up to ∼1% RH, probably forming hydroxyls. Water grows rapidly above 1% RH, indicative of the formation of a molecular water film. The molecular water film formed reaches more than one monolayer in thickness at 10% RH. We show that the energy separation between Ge4+ and Ge0+ signals in Ge3d spectra increases with RH until it reaches 1%. In addition, the collapse of an initial abrupt GeO2/Ge interface is demonstrated in this humidity range, indicating that water molecules in the gas phase infiltrate into the permeable GeO2 film, and water-related species accumulate at the GeO2/Ge interface. We propose that water-related species emit electrons to the Ge bulk and positive charges are created in GeO2 close to the GeO2/Ge interface, which is the origin of the specific features of Ge3d spectra. These positive charges are likely to be the cause of the reported negative shift of the flatband voltage in metal-oxide-semiconductor (Ge) capacitors with air-exposed GeO2.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Water Growth on GeO₂/Ge(100) Stack and Its Effect on the Electronic Properties of GeO₂

Mura¹,

Hideshima²,

Liu

et al. 2012

J. Phys. Chem. C

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“…In Fig. 9a, as the oxygen vacancy activated by the nitrogen plasma, the V o energy level below the conduction band [24][25][26] of HfO 2 is occupied by electrons. The band offset parameters are from Bersch.…”

Section: Resultsmentioning

confidence: 99%

Multi-Vt Performance Dependence on Capping Layer Position by NPT for PMOS Device Applications

Yao

2019

ECS J. Solid State Sci. Technol.

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In this paper, we present the comprehensive investigation of multi-Vt performance dependence on ALD-TiN capping layer position by NPT (nitrogen plasma treatment) process. The basic performance of fabricated PMOSCAPs are strongly dependent on the capping layer position by NPT process. 1) Flat-band voltage (VFB) negative shift is suppressed by increasing capping layer thickness before NPT process and EWF is toward band edge for the low power PMOS application, compared to the direct NPT at high-k surface. 2) Without capping layer shielding, the direct NPT process at HfO2 (high-k) surface brings out the oxygen vacancy generation and metal gate fermi level pinning and EWF toward band center for high performance PMOS application, while the capping layer can shield the nitrogen plasma with improvement of equivalent oxide thickness (EOT) and bulk trap density (Not). 3) The interface trap density (Dit) by conductance method is found to be significantly reduced by 35% compared to NPT process applied at capping layer top position. 4) The unique charge neutrality and oxygen vacancy model incorporating with capping layer shielding is reasonably proposed and successfully explains the above multi-Vt performance dependence on NPT position. The investigation of multi-Vt performance on capping layer position dependence by NPT will encourage the process improvement and advance HKMG technology for PMOS device multi-applications.

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“…Au is not easy to oxidation because of its Chemical stability, are often used as a metal electrode. For the Au/Hf-based gate stacks/Si capacitor without the surface treatment, the Au/Hf-based gate interface is thought to be stabilized by the adsorbates including oxygen to form Au-O-Hf bonds at the Au/Hf-based gate interface, thereby suppressing interface hybridization [14]. Au-gate capacitors have low leakage currents below 10 -7 A/cm 2 and obey SE till 1MV/cm(5V), also have highest breakdown voltage 10-10.5V(>2MV/cm), which makes Au the most appropriate for gate material in Ta 2 O 5 MOS structures, It has been reported by M. Pecovska-Gjorgjevich [9].…”

Section: Introductionmentioning

confidence: 99%

Influence of Metal Electrode(Ag,Au,Pt) on the Dielectric and Electrical Properties of HfTaO Capacitors

Yu¹,

Wu²,

Zhuge³

2011

AMR

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HfTaO-based MOS capacitors with different top electrode (Ag、Au、Pt) were successfully fabricated by dual ion beam sputtering deposition (DIBSD). We presented the effect of different metal gate on the capacity, flat band voltage shift, leakage current and conduction mechanism. It has been found that the Pt-electrode capacitor exhibited the highest accumulation capacitance. In addition, the largest hysteresis loop in Pt/HfTaO/Si capacitor during the forward-and-reverse voltage sweeping from +2.5V to -2.5V was observed. The result indicates the presence of a large amount of fixed charges or oxygen vacancies exist in interface Pt/HfTaO, which is consistent with the prediction from Qf results. It is proved that even though Eotof the Pt-electrode capacitor is lower than that of the Ag, Au-electroded, and that of leakage current still has the smallest value at a high electric field due to Pt with a high enough work function Φms(Pt)=5.65eV.

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Systematic study on work-function-shift in metal/Hf-based high-k gate stacks

Cited by 9 publications

References 6 publications

Water Growth on GeO₂/Ge(100) Stack and Its Effect on the Electronic Properties of GeO₂

Water Growth on GeO₂/Ge(100) Stack and Its Effect on the Electronic Properties of GeO₂

Multi-Vt Performance Dependence on Capping Layer Position by NPT for PMOS Device Applications

Influence of Metal Electrode(Ag,Au,Pt) on the Dielectric and Electrical Properties of HfTaO Capacitors

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Systematic study on work-function-shift in metal/Hf-based high-k gate stacks

Cited by 9 publications

References 6 publications

Water Growth on GeO2/Ge(100) Stack and Its Effect on the Electronic Properties of GeO2

Water Growth on GeO2/Ge(100) Stack and Its Effect on the Electronic Properties of GeO2

Multi-Vt Performance Dependence on Capping Layer Position by NPT for PMOS Device Applications

Influence of Metal Electrode(Ag,Au,Pt) on the Dielectric and Electrical Properties of HfTaO Capacitors

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Product

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Water Growth on GeO₂/Ge(100) Stack and Its Effect on the Electronic Properties of GeO₂

Water Growth on GeO₂/Ge(100) Stack and Its Effect on the Electronic Properties of GeO₂