Reliability of MOS devices with tungsten gates

Palumbo, F.; Lombardo, S.; Stathis, J. H.; Narayanan, V.; McFeely, F. R.; Yurkas, J.

doi:10.1016/j.mee.2003.12.014

Cited by 3 publications

(7 citation statements)

References 13 publications

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“…During the first ≈10 s, the I – t curves display a constant current level, where its magnitude depends on the applied voltage according to the I – V curves marked as (2) in Figure b. After ≈10 s the gate current starts increasing and results in a noisy and progressive degradation process similar to those reported in the literature for the cases of HfO 2 and SiO 2 . Note that the duration of the progressive degradation is significant, i.e., it takes ≈100 s until reaching levels of some µA.…”

Section: Resultssupporting

confidence: 68%

“…[19] and [20]) is that this setup can only measure very high current densities above 1 A cm −2 , because the effective tip/sample contact area is ≈100 nm 2 and the intrinsic electrical noise of the system is 1 pA. Therefore, the data in Figure 2 reveal for the first time that the initial degradation of h-BN dielectric stacks under real device operation conditions in fact is similar to that of other traditional insulators (e.g., HfO 2 , [12,31,32] Al 2 O 3 [33][34][35] ). Therefore, the data in Figure 2 reveal for the first time that the initial degradation of h-BN dielectric stacks under real device operation conditions in fact is similar to that of other traditional insulators (e.g., HfO 2 , [12,31,32] Al 2 O 3 [33][34][35] ).…”

Section: Breakdown Modementioning

confidence: 89%

“…(2) in Figure 1b. [33][34][35] Note that the duration of the progressive degradation is significant, i.e., it takes ≈100 s until reaching levels of some µA. [33][34][35] Note that the duration of the progressive degradation is significant, i.e., it takes ≈100 s until reaching levels of some µA.…”

Section: Breakdown Modementioning

confidence: 99%

See 2 more Smart Citations

Bimodal Dielectric Breakdown in Electronic Devices Using Chemical Vapor Deposited Hexagonal Boron Nitride as Dielectric

Palumbo

Liang

Shi

et al. 2018

Adv Elect Materials

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Multilayer hexagonal boron nitride (h‐BN) is an insulating 2D material that shows good interaction with graphene and MoS2, and it is considered a very promising dielectric for future 2D‐materials‐based electronic devices. Previous studies analyzed the dielectric properties of thick (>10 nm) mechanically exfoliated h‐BN nanoflakes (diameter < 20 μm) via conductive atomic force microscopy and applying very high voltages (>10 V); however, these methods are not scalable. In this work, the first device‐level reliability study of large area h‐BN dielectric stacks (grown via chemical vapor deposition) is presented, and the complete dielectric breakdown (BD) process is described. The experiments and calculations indicate that the BD process in metal/h‐BN/metal devices starts with a progressive current increase across the h‐BN stack until current densities up to 0.1 A cm−2 are reached. After that, the currents increase by sudden steps, which can be large (>1 order of magnitude, related to the BD of one/few h‐BN layers) or small (<1 order of magnitude, related to the lateral propagation of the BD). The bimodal BD process of h‐BN here presented (which cannot be detected via conductive atomic force microscopy) is essential to understand the reliability of 2D‐material‐based electronic devices using h‐BN as dielectric.

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Section: Resultssupporting

confidence: 68%

Section: Breakdown Modementioning

confidence: 89%

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Bimodal Dielectric Breakdown in Electronic Devices Using Chemical Vapor Deposited Hexagonal Boron Nitride as Dielectric

Palumbo

Liang

Shi

et al. 2018

Adv Elect Materials

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“…6). The low voltage threshold i s attributed to a mechanism producing the release of atomic hydrogen [ 6 ] . In the case of tungsten gates, independently on the stress polarity, we observe in first approximation the same QBD trend, also in this case with B threshold at about 5 V. Again, this is also visible as a kink in the second derivative of the I-V curves (Fig.…”

Section: Lo2mentioning

confidence: 99%

Degradation of ultra-thin oxides with tungsten gates under high voltage: wear-out and breakdown transient

Palumbo

Lombardo

Stathis

et al.

2004 IEEE International Reliability Physics Symposium. Proceedings

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An analysis of the dynamics of degradation of ultra-thin gate S i 0 2 films under accelerated high voltage stress, from the growth of defect concentration up to the final phase of the oxide breakdorm, was performed on MOS samples with Tungsten 8s gate material. INTRODUGnONMetal gates are considered a promising approach to increase transistor tranmduotance and to reduce gate resistance [I].Tungsten in particular, being a midgap work-function material, is considered particularly useful in the case of short channel fully depleted SO1 CMOS circuits. To introduce W, in addition to major technological challenges to be solved, concerns related to the reliability of the MOS stacks have to be taken into consideration. Moreover, the study of the reliability of metal gates with Si02 is in itself particularly interesting for the basic understanding of the dielectric breakdown (BD) phenomenon. In fact, according to the physical models most accepted and most adherent to the experimental observations concerning oxide degradation under high field stresses (anode hole injection and hydrogen release model [2]), the anode material plays a major role in the oxide w e a r a t . &e would expect that by changing the anode, both anode hole injection and hydrogen mlea~e should substantially vary. So oxide wear-out kinetics should depend on the gate material in stresses where the anode is the gate.Moreover, experimental evidences suggest that with poly-Si gates also the BD event in itself, i.e. the degradation of the initial BD spot leading to the final transistor failure (hard breakdown), has at low voltage the same physical mechanism that produces the oxide degradation 131. So this means that, again, the anode material should play a major role in the BD build-up rate kinetics. In addition, at high voltage there is a transition in the BD mode in which the failure becomes extremely fast [4]. The measurement of the voltage threshold at about 4 V has indicated a number of possible physical mechanisms involving a threshold energy of about 4 eV and responsible forthe BD mnaway.In order to check such aspects we have investigated the behaviour of two different anode materials: tungsten and poly-Si gates (both p+ and n+). The latter is used as reference. In this report we show the main results. EXPERIMENTAL Most of the work here reported refers to samples consisting in nand p M O S capacitors With gate material either tungsten or poly-Si (used BS control), oxide thickness ranging from 2 to 4 nm, and with Q78M4315-XA41$M.W@ZXl4 IEEE 122(100) oriented Si substrates. The analyzed combination of gate materials and substrates are therefore n+ poly-Si / p s i , W / p-Si, p+ poly-Si /"-Si, and W /"-Si.The evolution of the oxide degradation was investigated by monitoring both the growth of defect concentration up to the oxide breakdo-and the evolution of the initial BD spot toward hard BD. All MOS capacitor samples were stressed in accumulation with consecutives pulses at constant voltage (CVS) of duration ranging from IO" s up to IO" s. After each puls...

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“…Tungsten for example, being a midgap work-function material, is considered particularly useful in the case of short channel fully depleted SOI CMOS circuits. In this section we compare the behaviour of two different gate materials: tungsten and polycrystalline-Si gates (both p+ and n+) [23], with the same gate dielectric, i.e., a 2 nm thick thermally grown SiO 2 layer.…”

Section: Kinetics Of the Bd Event With Hi-k And Metal Layers In The Gmentioning

confidence: 99%

The Dielectric Breakdown in Gate Oxides under High Field Stress

Lombardo¹,

Stathis²,

Bersuker³

2009

ECS Trans.

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We review some experimental data on the dielectric breakdown (BD) phenomenon under high field stress of important gate insulators used in MOSFETs. We first discuss the case of silicon oxides or oxynitrides in the thickness range of tens of nm down to about 1 nm focusing on the kinetics of the final hard BD event.We describe the dependence of the BD current transient on the oxide thickness and the electric field and voltage. In particular we focus on the progressive BD phenomenon, i.e., a gradual growth of the BD leakage occurring in a time scale which in operation conditions is relevant. We then discuss the BD phenomemon in the case of ultra-thin high polarizability constant (high-k) dielectrics with metal gates in comparison to the conventional SiO 2 /poly-Si devices and outline critical differences between these gate stacks.

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Reliability of MOS devices with tungsten gates

Cited by 3 publications

References 13 publications

Bimodal Dielectric Breakdown in Electronic Devices Using Chemical Vapor Deposited Hexagonal Boron Nitride as Dielectric

Bimodal Dielectric Breakdown in Electronic Devices Using Chemical Vapor Deposited Hexagonal Boron Nitride as Dielectric

Degradation of ultra-thin oxides with tungsten gates under high voltage: wear-out and breakdown transient

The Dielectric Breakdown in Gate Oxides under High Field Stress

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