Dielectrics for future transistors

Bersuker, G.; Zeitzoff, P.; Brown, George; Huff, Howard R.

doi:10.1016/s1369-7021(04)00052-5

Cited by 86 publications

(40 citation statements)

References 13 publications

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“…Kumar [144] showed that hot carriers can create additional defects, but this is an additional effect. Figure 41 shows the effect transient charge trapping in the gate oxide has on a device characteristics, from Bersuker et al [145]. The gate voltage was cycled and plotted against the resulting FET drain current.…”

Section: Charge Trappingmentioning

confidence: 99%

High dielectric constant oxides

Robertson

2004

Eur. Phys. J. Appl. Phys.

1,531

828

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Abstract. The scaling of complementary metal oxide semiconductor (CMOS) transistors has led to the silicon dioxide layer used as a gate dielectric becoming so thin (1.4 nm) that its leakage current is too large. It is necessary to replace the SiO2 with a physically thicker layer of oxides of higher dielectric constant (κ) or 'high K' gate oxides such as hafnium oxide and hafnium silicate. Little was known about such oxides, and it was soon found that in many respects they have inferior electronic properties to SiO2, such as a tendency to crystallise and a high concentration of electronic defects. Intensive research is underway to develop these oxides into new high quality electronic materials. This review covers the choice of oxides, their structural and metallurgical behaviour, atomic diffusion, their deposition, interface structure and reactions, their electronic structure, bonding, band offsets, mobility degradation, flat band voltage shifts and electronic defects. The use of high K oxides in capacitors of dynamic random access memories is also covered. PACS

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Section: Charge Trappingmentioning

confidence: 99%

High dielectric constant oxides

Robertson

2004

Eur. Phys. J. Appl. Phys.

1,531

828

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“…Most critically, high-k devices suffer from poor channel mobility [4][5][6][7] and instabilities of the threshold potential ͑V T ͒. 8,9 It is understood that these drawbacks result from the high density of structural defects in the high-k films, 10 in particular, defects acting as electron traps. [11][12][13] These defects were shown to form localized states in the band gap, whose occupancy may vary with the external chemical potential.…”

Section: Introductionmentioning

confidence: 99%

The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies

Gavartin

Foster

Bersuker

et al. 2005

Journal of Applied Physics

155

111

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Using ab initio density functional total energy and molecular dynamics simulations, we study the effects of various forms of nitrogen post deposition anneal (PDA) on the electric properties of hafnia in the context of its application as a gate dielectric in field effect transistors (FET). We consider the atomic structure and energetics of nitrogen containing defects which can be formed during the PDA in various N-based ambients: N2, N + 2 , N, NH3, NO, N2O. We analyse the role of such defects in fixed charge accumulation, electron trapping and in the growth of the interface SiO2 layer. We find that nitrogen anneal of the oxides leads to an effective immobilization of native defects such as oxygen vacancies and interstitial oxygen ions, which may inhibit growth of silica layer. Nitrogen in any form effectively incorporates into the pre-existing oxygen vacancies and, therefore may decrease the concentration of shallow electron traps. However, nitrogen in any form is unlikely to significantly reduce the fixed charge in the dielectric.

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“…The leading candidate is presently HfO 2 [1][2][3][4][5]. However, the performance of devices using high-K gate oxides is unsatisfactory in a number of respects [5][6][7]. Hence, while it is clear that SiO 2 must be replaced, it is also clear that the electronic properties of the high-K oxides are presently poorer than SiO 2 in that they have a higher concentration of bulk defects and a poorer interface with Si.…”

Section: Introductionmentioning

confidence: 99%

“…Firstly, there is a large charge trapping [7][8][9][10][11], which gives rise to a time-dependent bias instability [7,8]. The time dependence places the trap levels around the Si conduction band edge [8], and the thickness dependence suggests that the traps are bulk traps not interface traps [10].…”

Section: Introductionmentioning

confidence: 99%

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Defect energy states in high‐K gate oxides

Xiong

Robertson²,

Clark

2006

Physica Status Solidi (b)

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PACS 71.15.Mb, 71.55.HtThe electrical energy levels of the different charge states of the oxygen vacancy and the oxygen interstitial in HfO 2 are calculated, using density functional methods which do not need a band gap correction. Lattice distortions around the defect sites produce substantial shifts in the energy levels. The energy levels are aligned to those of the Si channel. In HfO 2 , the oxygen vacancy gives an energy level in the Si gap or just above the gap, depending on its charge state. The O vacancy is identified as the main electrically active defect and trap. The oxygen interstitial gives levels just above the oxide valence band, and the neutral interstitial also gives a level near the Si conduction band. The defect wavefunctions are given.

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Dielectrics for future transistors

Cited by 86 publications

References 13 publications

High dielectric constant oxides

High dielectric constant oxides

The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies

Defect energy states in high‐K gate oxides

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