On the positive channel threshold voltage of metal gate electrodes on high-permittivity gate dielectrics

Schaeffer, J.; Gilmer, D. C.; Samavedam, S.; Raymond, M.; Haggag, A.; Kalpat, S.; Steimle, B.; Capasso, C.; White, Bruce

doi:10.1063/1.2781551

Cited by 17 publications

(11 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results mean that an electron trapping/detrapping mechanism was adopted and trap sites were not generated during stress conditions. 44 An improved dielectric/channel interface trapping site may lead to smaller voltage shifts.…”

Section: Resultsmentioning

confidence: 99%

Boron-Doped Peroxo-Zirconium Oxide Dielectric for High-Performance, Low-Temperature, Solution-Processed Indium Oxide Thin-Film Transistor

Park

Yoo

Lee

et al. 2013

ACS Appl. Mater. Interfaces

115

139

View full text Add to dashboard Cite

We developed a solution-processed indium oxide (In2O3) thin-film transistor (TFT) with a boron-doped peroxo-zirconium (ZrO2:B) dielectric on silicon as well as polyimide substrate at 200 °C, using water as the solvent for the In2O3 precursor. The formation of In2O3 and ZrO2:B films were intensively studied by thermogravimetric differential thermal analysis (TG-DTA), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT IR), high-resolution X-ray diffraction (HR-XRD), and X-ray photoelectron spectroscopy (XPS). Boron was selected as a dopant to make a denser ZrO2 film. The ZrO2:B film effectively blocked the leakage current at 200 °C with high breakdown strength. To evaluate the ZrO2:B film as a gate dielectric, we fabricated In2O3 TFTs on the ZrO2:B dielectrics with silicon substrates and annealed the resulting samples at 200 and 250 °C. The resulting mobilities were 1.25 and 39.3 cm(2)/(V s), respectively. Finally, we realized a flexible In2O3 TFT with the ZrO2:B dielectric on a polyimide substrate at 200 °C, and it successfully operated a switching device with a mobility of 4.01 cm(2)/(V s). Our results suggest that aqueous solution-processed In2O3 TFTs on ZrO2:B dielectrics could potentially be used for low-cost, low-temperature, and high-performance flexible devices.

show abstract

Section: Resultsmentioning

confidence: 99%

Boron-Doped Peroxo-Zirconium Oxide Dielectric for High-Performance, Low-Temperature, Solution-Processed Indium Oxide Thin-Film Transistor

Park

Yoo

Lee

et al. 2013

ACS Appl. Mater. Interfaces

115

139

View full text Add to dashboard Cite

show abstract

“…The extrinsic Fermi pinning is most noticeable for p-metals on smaller EOT stacks. This is known as the V t roll-off effect [12], as was shown in Fig 52. Song [273], Akiyama [274], Schaeffer [275] and Bersuker [276] have produced models to explain this effect, based on oxygen transfer. Bersuker [276] attributes rol-off to the formation of positively charged O vacancies close to the channel.…”

Section: Extrinsic Pinning Modelsmentioning

confidence: 99%

“…Given that scavenging can still be used for gate last, it is important to understand the degree of V t control that can be achieved [311][312][313]. In particularly, there is the problem of V t roll-off for the pFET [275]. Fig 74 plots the V t vs EOT for gate last stacks, including the scavenged regime [312].…”

Section: Scavenging and Ultra-low Eotmentioning

confidence: 99%

High-K materials and metal gates for CMOS applications

Robertson

Wallace

2015

Materials Science and Engineering: R: Reports

629

367

View full text Add to dashboard Cite

The scaling of complementary metal oxide semiconductor (CMOS) transistors has led to the silicon dioxide layer used as a gate dielectric becoming so thin that the gate leakage current becomes too large. This led to the replacement of SiO 2 by a physically thicker layer of a higher dielectric constant or 'high-K' oxide such as hafnium oxide. Intensive research was carried out to develop these oxides into high quality electronic materials. In addition, the incorporation of Ge in the CMOS transistor structure has been employed to enable higher carrier mobility and performance. This review covers both scientific and technological issues related to the high-K gate stack-the choice of oxides, their deposition, their structural and metallurgical behaviour, atomic diffusion, interface structure, their electronic structure, band offsets, electronic defects, charge trapping and conduction mechanisms, reliability, mobility degradation and oxygen scavenging to achieve the thinnest oxide thicknesses. The high K oxides were implemented in conjunction with a replacement of polcryslliane Si gate electrodes with metal gates. The strong metallurgical interactions between the gate electrodes and the HfO 2 which resulted an unstable gate threshold voltage resulted in the use of the lower temperature 'gate last' process flow, in addition to the standard 'gate first' approach. Work function control by metal gate electrodes and by oxide dipole layers is discussed. The problems associated with high K oxides on Ge channels are also discussed. Glossary ALD atomic layer deposition CB conduction band CBO conduction band offset CMOS complimentary metal oxide semiconductor CNL charge neutrality level CV capacitance voltage CVD chemical vapour deposition DB dangling bond DOS density of states EA electron affinity ECT equivalent capacitance thickness EOT equivalent oxide thickness ESR electron spin resosnance EWF effective work function FET field effect transistor GGA generalised gradient approximation LDA local density approximation MEIS medium energy ion scattering MIGS metal induced gap states MOCVD metla organic chemical vapour deposition MOS metal oxide semiconductor MOSFET metal oxide semiconductor field effect transistor MOx arbitrary metal oxide NMOS n-type MOS PMOS p-type MOS RCS remote Coulombic scattering RPS remote phonon scattering SBH Schottky barrier height TAT trap assisted tunnelling T inv inversion thickness Vt threshold voltage (of FET) Vfb flat band voltage VB valence band VBO valence band offset WF work function

show abstract

“…This relationship between gate dielectric thickness and threshold voltage is similar to that observed in silicon field-effect TFTs with very thin inorganic oxide gate dielectrics. 15 The greatest concern with thin gate dielectrics is the undesirable charge leakage through the dielectric. Figure 2͑e͒ shows that the gate current in the TFTs with C6-SAM is approximately the same as that in TFTs without any SAM, about 1 nA.…”

mentioning

confidence: 99%

Effects of the alkyl chain length in phosphonic acid self-assembled monolayer gate dielectrics on the performance and stability of low-voltage organic thin-film transistors

Fukuda

Hamamoto

Yokota

et al. 2009

Applied Physics Letters

130

121

View full text Add to dashboard Cite

We have fabricated pentacene organic thin-film transistors ͑TFTs͒ using self-assembled monolayers ͑SAMs͒ based on alkyl-phosphonic acids with five different alkyl chain lengths as the gate dielectric and investigated the relationship between the SAM chain length and the electrical performance and stability of the transistors. A SAM chain length of 14 carbon atoms provides a maximum TFT mobility of 0.7 cm 2 / V s, along with an on/off current ratio greater than 10 5. We have also investigated the bias stress effect in these TFTs and found that the change in drain current is substantially less severe than in pentacene TFTs with polymer gate dielectrics.

show abstract

On the positive channel threshold voltage of metal gate electrodes on high-permittivity gate dielectrics

Cited by 17 publications

References 11 publications

Boron-Doped Peroxo-Zirconium Oxide Dielectric for High-Performance, Low-Temperature, Solution-Processed Indium Oxide Thin-Film Transistor

Boron-Doped Peroxo-Zirconium Oxide Dielectric for High-Performance, Low-Temperature, Solution-Processed Indium Oxide Thin-Film Transistor

High-K materials and metal gates for CMOS applications

Effects of the alkyl chain length in phosphonic acid self-assembled monolayer gate dielectrics on the performance and stability of low-voltage organic thin-film transistors

Contact Info

Product

Resources

About