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In this letter, evidence of plasma-induced damage (PID) occurring in ${p}$ -type FinFET Germanium devices due to BEOL processing is reported. The ability of high-pressure anneal (HPA) (20 min at 450° with 20 atm pressure) to cure this damage is investigated by comparing different ambients (hydrogen and deuterium) with the reference case without HPA. The degradation and partial recovery during anneal of the threshold voltage, the transconductance, and the subthreshold slope are observed. Further, bias temperature instability stress is employed to evaluate the impact of PID in terms of reliability. It is found that the damage observed in the dc and reliability measurements is more efficiently cured by the H2 ambient than the D2 ambient. [ABSTRACT FROM AUTHOR]

We have measured the low-frequency 1/ f noise of Si0.55Ge0.45 p MOSFETs with a Si capping layer and SiO2/HfO2/TiN gate stack as a function of frequency, gate voltage, and temperature (100–440 K). The magnitude of the excess drain voltage noise power spectral density ( \textitS {vd} ) is unaffected by negative-bias-temperature stress (NBTS) for temperatures below ~250 K, but increases significantly at higher temperatures. The noise is described well by the Dutta-Horn model before and after NBTS. The noise at higher measuring temperatures is attributed primarily to oxygen-vacancy and hydrogen-related defects in the SiO2 and HfO2 layers. At lower measuring temperatures, the noise also appears to be affected strongly by hydrogen-dopant interactions in the SiGe layer of the device. [ABSTRACT FROM PUBLISHER]

An experimental low-frequency noise (LFN) assessment of long channel Ge pFinFET devices fabricated in different shallow trench isolation (STI) processes is presented, taking into consideration devices with fin widths from 100 nm (planar-like) down to 20 nm. In addition, the correlation among LFN parameters, hole mobility and threshold voltage, is also evaluated. The carrier number fluctuation ( $\Delta N$ ) model is confirmed as dominant mechanism for all studied Ge pFinFETs and there is no correlation with the used STI process. From the LFN, it is evidenced that the Coulomb scattering mobility mechanism plays an important role for STI-first process, resulting in a mobility degradation. [ABSTRACT FROM PUBLISHER]

This letter characterizes the generation–recombination noise of Ge pFinFETs, for three different integration schemes: shallow trench isolation (STI) first strained devices; STI last for relaxed and strained ones. It is shown that many Lorentzians exhibit a V\mathrm {GS} -independent and thermally activated characteristic frequency. This points out that the responsible defects are located inside the fin and they are found for all studied process conditions. One type of defect with a time constant value of 10 ms at room temperature is process-independent. Regarding the defects, their activation energies and hole capture cross sections have been extracted for fin widths varying from planar-like devices to narrow ones. It is shown that the STI last strained and relaxed devices yield a surface trap density three orders of magnitude above the typical value obtained for a blanket wafer. [ABSTRACT FROM PUBLISHER]

We investigate negative-bias temperature instabilities in SiGe pMOSFETs with SiO 2/HfO 2 gate dielectrics. The measured activation energies for interface-trap charge buildup during negative-bias temperature stress are lower for SiGe channel pMOSFETs with SiO 2/HfO 2 gate dielectrics and Si capping layers than for conventional Si channel pMOSFETs with SiO 2 gate dielectrics. Electron energy loss spectroscopy and scanning transmission electron microscopy images demonstrate that Ge atoms can diffuse from the SiGe layer into the Si capping layer, which is adjacent to the SiO 2/HfO 2 gate dielectric. Density functional calculations show that these Ge atoms reduce the strength of nearby Si–H bonds and that Ge–H bond energies are still lower, thereby reducing the activation energy for interface-trap generation for the SiGe devices. Activation energies for oxide-trap charge buildup during negative-bias temperature stress are similarly small for SiGe pMOSFETs with SiO 2/HfO 2 gate dielectrics and Si pMOSFETs with SiO 2 gate dielectrics, suggesting that, in both cases, the oxide-trap charge buildup likely is rate-limited by hole tunneling into the near-interfacial SiO 2. [ABSTRACT FROM PUBLISHER]

TCAD finite-element process simulations have been performed on Ge-channel n and pMOSFETs with embedded source/drain stressors or a strained Ge channel on a relaxed SiGe strain relaxed buffer (SRB), respectively, and compared with nanobeam diffraction strain measurements. While there is overall a good agreement between the simulated and experimental strain profiles, some deviations may occur, due to the presence of extended defects in the strain relaxed Ge buffer layers. This highlights the importance of selection of a strain-free reference in the relaxed Ge or SiGe SRB. [ABSTRACT FROM AUTHOR]

In this paper, we have fabricated high-performance Si0.45Ge0.55 implant-free quantum well (IFQW) pFET with embedded SiGe source/drain stressor. This device showed high drive current of 1.28 mA/ \mu m at I_{\mathrm {\scriptstyle OFF}\_{D}} of 160 nA/ \mu $ m with channel length/width of 30 nm/0.16 $\mu $ m ( $V_{{\rm {DD}}} =-1$ V). Conventional ion-implanted extension is replaced with in situ boron-doped epitaxial Si0.75Ge0.25 layer. This enables lower process temperature which can maintain an integrity of Si0.45Ge0.55 film and thus higher hole mobility. In narrower width devices, we observed significant hole mobility boost ( $1.9\times $ improvement from active width of 10 to $0.1~\mu $ m). This is due to the relaxation of unwanted transverse stress in Si0.45Ge0.55 channel applied from Si substrate. IFQW devices show improved short channel control thanks to the epitaxially formed raised extension structure compared with conventional devices which have implanted extension. Achieved device performance is one of the best among all Si1–xGex-based channel pFET up to date. [ABSTRACT FROM AUTHOR]

Endurance is investigated on one transistor floating body RAM cells processed on a silicon-on-insulator substrate with ultrathin buried oxide, and programmed using the bipolar junction transistor current inherent in MOSFETs. During the hole generation step, defects are generated close to the drain. These defects not only reduce the retention time but also result in a lower hole generation rate as a function of the number of cycles, which leads to a write 1 failure. We have shown that standard junction devices with a lightly doped drain (LDD) region are more enduring than extensionless devices with the LDD left undoped. This is owing to the poor spacer oxide on top of the extensionless region where holes are generated. [ABSTRACT FROM PUBLISHER]

Due to a significantly reduced negative-bias temperature instability (NBTI), (Si)Ge channel pMOSFETs are shown to offer sufficient reliability at ultrathin equivalent oxide thickness. The intrinsically superior NBTI robustness of the MOS system consisting of a Ge-based channel and a \SiO2/ \HfO2 dielectric stack is ascribed to a reduced availability of interface precursor defects and to a significantly reduced interaction of channel carriers with gate dielectric defects due to a favorable energy decoupling. Owing to this effect, a significantly reduced time-dependent variability of nanoscale devices is also observed. The superior reliability is shown to be process and architecture independent by comparing both our results on a variety of Ge-based device families and published data of other groups. [ABSTRACT FROM PUBLISHER]

We report extensive experimental results of the negative bias temperature instability (NBTI) reliability of SiGe channel pMOSFETs as a function of the main gate-stack parameters. The results clearly show that this high-mobility channel technology offers significantly improved NBTI robustness compared with Si-channel devices, which can solve the reliability issue for sub-1-nm equivalent-oxide-thickness devices. A physical model is proposed to explain the intrinsically superior NBTI robustness. [ABSTRACT FROM AUTHOR]

The time-dependent variability of nanoscaled \Si0.45 \Ge0.55 pFETs with varying thicknesses of the Si passivation layer is studied. Single charge/discharge events of gate oxide defects are detected by measuring negative bias-temperature instability (NBTI)-like threshold voltage (Vth) shift relaxation transients. The impact of such individually charged defect on device Vth is observed to be exponentially distributed. SiGe channel devices with a reduced thickness of their Si passivation layer show a reduced average number of active defects and a reduced average impact per charged defect on device Vth. Our model for the superior reliability of the SiGe channel technology previously proposed in Part I, which is based on the energy decoupling between channel holes and dielectric defects, is shown to also explain these experimental observations. Other reliability mechanisms, such as \1/f noise, body biasing during NBTI, channel hot carriers, and time-dependent dielectric breakdown, are also investigated. None of these mechanisms are observed to constitute a showstopper for the reliability of this promising novel technology. [ABSTRACT FROM AUTHOR]

In this paper, the potential of Silicon-Germanium (SiGe) technology for VLSI logic applications is investigated from a circuit perspective for the first time. The study is based on experimental measurements on 45-nm SiGe pMOSFETs with a high-\kappa/metal gate stack, as well as on 45-nm Si pMOSFETs with identical gate stack for comparison. In the reference SiGe technology, an innovative technological solution is adopted that limits the SiGe material only to the channel region. The resulting SiGe device merges the higher speed of the Ge technology with the lower leakage of the Si technology. Appropriate circuit- and system-level metrics are introduced to identify the advantages offered by SiGe technology in VLSI circuits. Analysis is performed in the context of next-generation VLSI circuits that fully exploit circuit- and system-level techniques to improve the energy efficiency through aggressive voltage scaling, other than low-leakage techniques. Analysis shows that the SiGe technology has more efficient leakage-delay and dynamic energy-delay trade-offs at nominal supply, compared to Si technology. Moreover, it is shown that the traditional analysis performed at nominal supply actually underestimates the benefits of SiGe pMOSFETs, since the speed advantage of SiGe VLSI circuits is further emphasized at low voltages. This demonstrates that SiGe VLSI circuits benefit from aggressive voltage scaling significantly more than Si circuits, thereby making SiGe devices a very promising alternative to Si transistors in next-generation VLSI systems. [ABSTRACT FROM PUBLISHER]

This study combines direct measurements of strain, electrical mobility measurements, and a rigorous modeling approach to provide insights about strain-induced mobility enhancement in FinFETs and guidelines for device optimization. Good agreement between simulated and measured mobility is obtained using strain components measured directly at device level by a novel holographic technique. A large vertical compressive strain is observed in metal gate FinFETs, and the simulations show that this helps recover the electron mobility disadvantage of the (110) FinFET lateral interfaces with respect to (100) interfaces, with no degradation of the hole mobility. The model is then used to systematically explore the impact of stress components in the fin width, height, and length directions on the mobility of both n- and p-type FinFETs and to identify optimal stress configurations. Finally, self-consistent Monte Carlo simulations are used to investigate how the most favorable stress configurations can improve the on current of nanoscale MOSFETs. [ABSTRACT FROM AUTHOR]

This letter reports on the spike anneal temperature influence on the retention time of 1T-dynamic random access memory cells using a single silicon-on-insulator transistor on ultrathin buried oxide wafers. A 20 ^\circC temperature difference (from 1070 ^\circC to 1050 ^\circC ) in the peak process temperature during the spike anneal after the source/drain implantation caused an order of magnitude increment in the retention time. The lower temperature analyzed (1050 ^\circC ) increases the retention time up to 100 ms because of the lower drain electrical field and tunneling current. [ABSTRACT FROM AUTHOR]