A Percolative Approach to Electromigration Modelling

Pennetta, C.; Reggiani, L.; Trefán, Gy.; Fantini, Fausto; Scorzoni, A.; Munari, Ilaria De

doi:10.1557/proc-612-d2.7.1

Cited by 6 publications

(6 citation statements)

References 12 publications

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“…The stepwise variations in Figure 5 c on top of the overall current decay could be explained by the stochastic change in the conduction path due to persistent trapping and detrapping of electrons leading to the rearrangement of the network composed of occupied traps. [ 47,48 ] Such behaviors have been successfully modeled for percolation networks with competing defect generation and defect recovery mechanisms, [ 48,49 ] again supporting electron trapping as the mechanism of the observed switching effect in oxidized graphene electrodes. The difference in retention time between the functionalized graphene electrodes in the MLG/Ta 2 O 5-x /TaO y /MLG devices and the annealed graphene samples may be explained by the different interfaces in the two types of devices, as the TaO y layer passivating the graphene fi lm could change the energy profi le of the electron traps and make it easier for the trapped electrons to escape in the MLG/Ta 2 O 5-x /TaO y /MLG devices.…”

Section: Communicationmentioning

confidence: 72%

Oxide Resistive Memory with Functionalized Graphene as Built‐in Selector Element

Yang

Lee

et al. 2014

Advanced Materials

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transfer was repeated several times (typically ∼3) in order to further improve the conductance of the electrodes, therefore forming a multilayer graphene (MLG) stack. An optical graph of the glass substrate with the MLG fi lm on top is displayed in Figure 1 b, showing high transparency. Subsequently, the MLG fi lm was patterned into bottom electrodes (BEs) with widths of 1-5 µm by photolithography and O 2 plasma etching (Figure 1 a2). Au/Ti metal contacts (B1 and B2) were then deposited onto the two ends of the MLG BE afterwards to minimize the contact resistance to the external probes in electrical measurements (Figure 1 a3). Following BE defi nition, a bilayer oxide structure consisting of an oxygen rich Ta 2 O 5-x layer (∼5 nm) and an oxygen defi cient TaO y layer (∼40 nm) serving as the switching medium of the RRAM devices was successively deposited by radio-frequency (RF) sputtering and reactive sputtering (400 °C, O 2 /Ar = 3%), respectively, without breaking the vacuum (Figure 1 a4). Similar to steps 1-3 in Figure 1 a, multiple monolayer graphene transfer, O 2 plasma etching and Au/Ti metal contacts deposition were conducted again to fabricate the top electrodes (TEs) that complete the crossbar memory structure ( Figure 1 a5-7). Finally, a pad opening step was performed through a timed reactive ion etching (RIE) process to remove the Ta 2 O 5-x /TaO y bilayer on top of the bottom contact Au/Ti pads (Figure 1 a8). The sizes of the RRAM devices in this work range from 1-5 µm × 1-5 µm, and during measurements the voltage was applied on the TE with the BE grounded. Since resistive switching in Ta 2 O 5-x /TaO y bilayer devices is driven by internal oxygen vacancy redistribution, the change in deposition sequence should in principle only lead to a reversal of the switching polarity, as has been verifi ed by studies on devices with inert metal electrodes. [ 25 ] However, in the case of devices with MLG electrodes, the stacking sequence of the bilayer was found to be critical in determining the device behavior, as shown in Figure 1 d,e. When the Ta 2 O 5-x layer was deposited fi rst on the graphene BE followed by TaO y deposition, the MLG/TaO y /Ta 2 O 5-x /MLG (top to bottom) devices exhibited conventional bipolar resistive switching characteristics similar to the results obtained with metal electrodes, [ 25,26 ] as shown in Figure 1 d. Such switching behavior can be well understood in the picture of V O exchange between the Ta 2 O 5-x and the V O -rich TaO y layers, [ 8,26,27 ] and the switching polarity with positive SET and negative RESET voltages is a natural result of the device confi guration since the V O reservoir (the oxygen defi cient TaO y layer) sits on top in this case. The linear on-state behavior is also consistent with Ohmic conduction for the V O -based conducting fi laments in Ta 2 O 5-x /TaO y RRAMs. [ 8,26,27 ] Driven by the continuing demand for improved computing capability, the semiconductor industry has been constantly looking for a fast, reliable, scalable yet nonvolatile memory technolo...

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Section: Communicationmentioning

confidence: 72%

Oxide Resistive Memory with Functionalized Graphene as Built‐in Selector Element

Yang

Lee

et al. 2014

Advanced Materials

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“…From Monte Carlo simulations we found that also for biased percolation the resistance evolution follows a scaling relation R͑t͒ ϳ jt 2 tj 2m B , with m B 0.22 6 0.02 [18]. We note that the value of m B depends in general on current and temperature and thus on the importance of Joule heating effects, which control the correlations present in the degradation process [18]. Since in this case the process of defect creation is driven by the external current, the selective breaking of the crucial resistors suppresses the saturation region of the breakdown resistance typical of standard percolation.…”

mentioning

confidence: 93%

“…Again the curve marked by circles represents the evolution of the network resistance R͑t͒, while the squares represent that of R͑t 2 t͒. From Monte Carlo simulations we found that also for biased percolation the resistance evolution follows a scaling relation R͑t͒ ϳ jt 2 tj 2m B , with m B 0.22 6 0.02 [18]. We note that the value of m B depends in general on current and temperature and thus on the importance of Joule heating effects, which control the correlations present in the degradation process [18].…”

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confidence: 96%

Scaling and Universality in Electrical Failure of Thin Films

2000

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We describe the electrical failure of thin films as a percolation in two-dimensional random resistor networks. We show that the resistance evolution follows a scaling relation expressed as R approximately epsilon(-&mgr;) where epsilon = (1-t/tau), tau is the time of electrical failure of the film, and &mgr; is the same critical exponent appearing in the scaling relation between R and the defect concentration. For uniform degradation the value of &mgr; is universal. The validity of this scaling relation in the case of nonuniform degradation is proved by discussing the case in which the failure is due to a filamentary defect growth. The existence of this relation allows predictions of failure times from early time measurements of the resistance.

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“…The aim of this paper is to address this issue by presenting a stochastic approach which simulates EM damages in metallic interconnects in terms of percolation in a random resistor network [18]. By extending a previously proposed model [19], here we present a complete study whose preliminar results have been reported in [20][21][22]. In our appproach, even if there is no direct motion of matter, the effects of mass transport are implicitely accounted for by our percolative and stochastic approach.…”

Section: Introductionmentioning

confidence: 99%

A percolative approach to electromigration in metallic lines

Pennetta¹,

Reggiani²,

Trefán³

et al. 2001

J. Phys. D: Appl. Phys.

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We present a stochastic model which simulates electromigration damage in metallic interconnects by biased percolation of a random resistor network in the presence of degradation and recovery processes. The main features of experiments including Black's law, times to failure distribution, current threshold for the onset of electromigration, etc are properly reproduced. Compositional effects showing up in early resistance changes measured on Al-0.5%Cu and Al-1%Si lines are also studied.

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A Percolative Approach to Electromigration Modelling

Cited by 6 publications

References 12 publications

Oxide Resistive Memory with Functionalized Graphene as Built‐in Selector Element

Oxide Resistive Memory with Functionalized Graphene as Built‐in Selector Element

Scaling and Universality in Electrical Failure of Thin Films

A percolative approach to electromigration in metallic lines

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