Search

Focused, pulsed X-rays are used to generate single-event transients (SETs) in metal–insulator–semiconductor (MIS)-gate AlGaN/GaN high-electron-mobility transistors (HEMTs) in order to investigate the mechanisms responsible for SETs. Unlike Schottky-gate GaN HEMTs, where current flows between gate and drain when the device is biased “OFF,” for the MIS-gate HEMTs, current flows between the source and drain. The presence of the SiNx insulating layer under the gate effectively blocks electrons on the gate from moving into the semiconductor. Short-duration SETs at the gate are caused by the collection of holes injected by the X-rays. SETs collected at the source and drain have an initial short-duration component, followed by a long-duration tail that can last for hundreds of nanoseconds. The long tails are due to positive charges (holes) that are less mobile than the electrons and so take longer to exit the HEMT, and to holes that become trapped at defects in the material. The holes lower the potential barrier between the source and the region under the gate, allowing for the injection of electrons that flow from the source to the drain. The durations of the SET tails are determined by the lifetimes of the trapped holes that are found to vary with X-ray photon energy and electrical bias. [ABSTRACT FROM AUTHOR]

The single-event transient response of a high-voltage complementary SiGe-on-silicon-on-insulator technology is investigated along with its temperature dependence using a pulse laser. The p-n-p silicon-germanium heterojunction bipolar transistor (SiGe HBT) shows a larger transient peak amplitude compared to the n-p-n SiGe HBT, which is largely related to the differences in total device volume and peak germanium content between the p-n-p and n-p-n devices. The effects of temperature on the transient response are also investigated using heaters and sensors mounted directly on the device-under-test package. The collector transient peak amplitude shows a negative temperature coefficient for a $V {_{\text {CB}}}$ of 0-V condition, for both the n-p-n and p-n-p devices. However, the temperature dependence of the transient peak amplitude becomes significantly weaker at $V {_{\text {CB}}}>0$ V. Calibrated TCAD simulations were performed to better understand the temperature dependence, and the simulations indicated that the electric field and mobility at higher $V {_{\text {CB}}}$ have a reduced temperature dependence than at a $V {_{\text {CB}}}$ of 0 V. The effects of self-heating are also explored using TCAD simulations and show that even under aggressive self-heating conditions, there is only less than 10% reduction in transient peak amplitude with the self-heating models turned on. The results shown suggest that this particular SiGe technology can be used for environments where highly energetic particles and high temperatures are encountered simultaneously. [ABSTRACT FROM AUTHOR]

We provide “best practices” for single-event transient (SET) mitigation using electrostatic discharge (ESD) protection techniques. We investigate the correlation between SET suppression and RF performance when ESD protection circuits for SET mitigation are combined with various RF switches. The three different single-pole single-throw (SPST) switch configurations (conventional design, floating body, and floating body/n-well) were implemented to provide insight on how to best apply dc ESD protection techniques for also achieving robust SET mitigation. Based on two-photon absorption laser experiments and RF measurements, a conventional SPST switch configuration shows relatively poor RF performance but is effective for SET mitigation due to the SET discharge current path provided by ESD protection circuit. On the other hand, the combination of the SPST switch and the ESD circuit, which exhibits the best RF performance among the three configurations, is relatively vulnerable to SETs. Based on these results, strategies and methodologies for ESD protection techniques to effectively mitigate SET are proposed. [ABSTRACT FROM AUTHOR]

An approach for determining the optimal laser parameters (i.e., pulse energy, focused spot size, wavelength, and pulse duration) for correlating single-event transients induced via two-photon absorption (TPA) and heavy ions is presented. The approach focuses on identification and extraction of waveform characteristics, or “features,” and minimizing the error between features produced by TPA and ions. Modifying optical parameters can directly impact the waveform features of the TPA-induced transients. Consequently, optimal laser parameters that minimize the error between features extracted for laser- and ion-induced waveforms can be determined. In this paper, the laser pulse energy and spot size were varied, while maintaining a fixed pulse duration and wavelength, and the resulting transients were compared to ion-induced transients. When the optimized optical parameters are used, excellent agreement was achieved between laser- and ion-induced transient waveforms in a silicon-germanium heterojunction bipolar transistor (SiGe HBT). In addition, a one-to-one correlation between heavy-ion linear energy transfer (LET) and laser pulse energy was obtained for a particular spot size ($\omega _{0} = 1.89\,\,\mu \text{m}$ (HW $1/e^{2}$)). These results show that a correlation between LET and pulse energy is achievable when the remaining optical parameters are selected appropriately. Although the results presented are for SiGe HBTs, the generality of the approach should allow it to be extended to other semiconductor platforms. [ABSTRACT FROM AUTHOR]

This correspondence comments on the correlation between measured and simulated charge collection in two diode structures presented in [1]. In [1], results from pulsed-laser-induced charge deposition via two-photon absorption revealed reasonable correlation between experimental data and simulations in some aspects but showed lack of correlation in terms of the measured and predicted magnitudes of the collected charge. The source of this poor agreement has recently been determined, and is attributed to an incorrect pulse energy calibration used for those experiments. With the proper energy calibration applied, the agreement between simulation and experiment is nearly quantitative for all observables in both devices. These results significantly strengthen the validity of the nonlinear optical beam propagation method numerical approach for accurately predicting pulsed-laser-induced charge deposition. [ABSTRACT FROM PUBLISHER]

A focused, pulsed x-ray beam was used to compare SET characteristics in pristine and proton-irradiated Al0.3Ga0.7N/GaN HEMTs. Measured SET amplitudes and trailing-edge decay times were analyzed as was the collected charge, obtained by integrating the SET pulses over time. SETs generated in proton-irradiated HEMTs differed significantly from those in pristine HEMTs with regard to the decay times and collected charge. The decay times have previously been shown to be attributed to charge trapping by defect states that are caused either by imperfect material growth conditions or by proton-induced displacement damage. The longer decay times observed for proton-irradiated HEMTs are attributed to the presence of additional deep traps created when protons lose energy as they collide with the nuclei of constituent atoms. Comparison of electrical parameters measured before and immediately following exposure to the focused x-ray beam showed little change, confirming the absence of significant charge buildup in passivation layers by the x-rays themselves. A major advantage of the pulsed x-ray technique is that the region under the metal gate can be probed for single-event transients from the top side, an approach incompatible with pulsed-laser SEE testing that involves the use of visible light. [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of a W-band (75–110 GHz) radar receiver front-end is investigated in this paper. A new technique to facilitate the SET testing of the high frequency transceivers is proposed and demonstrated experimentally. The entire radar receiver front-end, including the high frequency signal sources and modulators, were designed and fully integrated in 90 nm 300 GHz SiGe process technology (Global Foundries SiGe 9HP). Two-photon absorption (TPA) laser pulses were utilized to induce transient currents in different devices in various circuit blocks. The study shows how short transient pulses from the high frequency tuned circuits are propagated throughout the receiver and are broadened while passing through low-pass filters present at supply nodes and the low-pass filter following the down-conversion mixer, thus affecting the digital data at the output of the receiver. The proposed methodology allows the study of the effect of SETs on the recovered digital data at the output of the high frequency receivers, thus allowing bit error rate calculations. Comprehensive device and circuit level simulations were also performed, and a close agreement between the measurement results and simulation data was demonstrated. To the authors’ best knowledge, this is the first study of SET on full receiver at millimeter-wave (mmW) frequencies. [ABSTRACT FROM PUBLISHER]

Silicon-germanium heterojunction bipolar transistor (SiGe HBT) models are used in technology computer aided design (TCAD) to investigate single event transients induced by heavy-ion broadbeam and pulsed-laser two-photon absorption sources. A comparison between transient waveforms is provided, the proper extraction of heavy-ion broadbeam transients is discussed (along with circuit implications), and basic laser strike profiles are implemented in TCAD to provide insight into future design practices for simulation software to be used to describe laser-induced upsets in terms of an effective linear energy transfer (LET). [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of two different silicon-germanium (SiGe) X-band (8–12 GHz) low noise amplifier (LNA) topologies is fully investigated in this paper. The two LNAs were designed and implemented in 130nm SiGe HBT BiCMOS process technology. Two-photon absorption (TPA) laser pulses were utilized to induce transients within various devices in these LNAs. Impulse response theory is identified as a useful tool for predicting the settling behavior of the LNAs subjected to heavy ion strikes. Comprehensive device and circuit level modeling and simulations were performed to accurately simulate the behavior of the circuits under ion strikes. The simulations agree well with TPA measurements. The simulation, modeling and analysis presented in this paper can be applied for any other circuit topologies for SET modeling and prediction. [ABSTRACT FROM PUBLISHER]

The impact of semiconductor process scaling on the overall transient response of SiGe BiCMOS platforms is investigated. Pulsed-laser two-photon absorption (TPA) and heavy-ion broad-beam testing of SiGe HBT device and digital test structures across several generations of SiGe technologies are utilized to investigate the potential impacts of semiconductor process scaling (e.g., lateral/vertical scaling, changes in doping, Ge content, etc.) on the overall transient shape, magnitude, and duration. Technology scaling is shown to increase the single-event effect (SEE) sensitivity of SiGe HBTs (i.e., elevated collected charge, where 1st Gen. QC <3 rd Gen. QC <4 th Gen. QC ). Modern third-generation and fourth-generation devices under a forward-active bias (i.e., forward-biased EB junction, reverse-biased CB junction) exhibit a large diffusive transient component between the emitter and collector terminals, driving an elevation in collected charge. 3-D TCAD modeling is utilized to understand the fundamental transient mechanisms and assess the primary scaling factors affecting SEE sensitivity. Ion-strike simulations show that bulk traps can substantially enhance the charge collection mechanisms within these devices. These results suggest that SiGe technology scaling may have a strong impact on the radiation-induced transient response of SiGe HBTs, with future SiGe technology generations potentially exhibiting increased sensitivities to single-event effects. [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of the pre-amplification stage of two latched comparators designed using either npn or pnp silicon-germanium heterojunction bipolar transistors (SiGe HBTs) is investigated via two-photon absorption (TPA) carrier injection and mixed-mode TCAD simulations. Experimental data and TCAD simulations showed an improved SET response for the pnp comparator circuit. 2-D raster scans revealed that the devices in the pnp circuit exhibit a reduction in sensitive area of up to 80% compared to their npn counterparts. In addition, by sweeping the input voltage, the sensitive operating region with respect to SETs was determined. By establishing a figure-of-merit, relating the transient peaks and input voltage polarities, the pnp device was determined to have a 21.4% improved response with respect to input voltage. This study has shown that using pnp devices is an effective way to mitigate SETs, and could enable further radiation-hardening-by-design techniques. [ABSTRACT FROM PUBLISHER]

A cascode configuration with inverse-mode (IM) common-emitter silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) is proposed for the mitigation of single-event transients (SETs) in low-noise amplifiers (LNAs). Conventionally, despite their SET-mitigation capability, IM SiGe HBTs have been considered to be unsuitable for active gain stages due to severe degradation in RF performance. However, with the benefits of aggressive technology scaling, the high frequency performance of IM SiGe HBTs has been significantly improved, thereby enabling them to be utilized in active gain stages with acceptable RF performance. The cascode with IM common-emitter and common-base SiGe HBTs is used for a 2.4 GHz prototype LNA and it achieves adequate RF gain (10 dB) and noise figure (1.9 dB). With regard to SET mitigation, a through-wafer two-photon absorption pulsed-laser experiment is conducted to test the efficacy of this radiation-hardening approach in an advanced 90 nm SiGe BiCMOS platform. The proposed IM-SiGe-HBT-based LNA exhibits 85% reduction in transient peaks compared to the conventional forward-mode cascode LNA. [ABSTRACT FROM PUBLISHER]

The propagation of Analog Single Event Transients (ASETs) to multiple outputs of Bipolar Junction Transistor (BJTs) Integrated Circuits (ICs) is reported for the first time. The results demonstrate that ASETs can appear at several outputs of a BJT amplifier or comparator as a result of a single ion or single laser pulse strike at a single physical location on the chip of a large-scale integrated BJT analog circuit. This is independent of interconnect cross-talk or charge-sharing effects. Laser experiments, together with SPICE simulations and analysis of the ASET’s propagation in the s-domain are used to explain how multiple-output transients (MOTs) are generated and propagate in the device. This study demonstrates that both the charge collection associated with an ASET and the ASET’s shape, commonly used to characterize the propagation of SETs in devices and systems, are unable to explain quantitatively how MOTs propagate through an integrated analog circuit. The analysis methodology adopted here involves combining the Fourier transform of the propagating signal and the current-source transfer function in the s-domain. This approach reveals the mechanisms involved in the transient signal propagation from its point of generation to one or more outputs without the signal following a continuous interconnect path. [ABSTRACT FROM PUBLISHER]

Circuit parameters and configuration are very important when studying the synergistic effects total dose/SET. We explore a method combining dynamic parameter measurement and spectrum analysis which lead to a better understanding of this complex phenomenon. In this paper symbolic circuit analysis is used to obtain the relationship between input, output and noise injection due to photocurrent generation in the form of a rational function using symbolic variables in the complex frequency domain. This simulation technique was able to predict the impact of (i) total dose level, (ii) circuit parameters, and (iii) the injected energy on the ASET shapes. Basic mechanisms as field collapse and collection efficiency were also predicted and assessed. [ABSTRACT FROM PUBLISHER]

Single-event transients (SETs) were investigated in Al0.3{Ga0.7}{N/GaN} high-electron-mobility transistors (HEMTs) using optical excitation via two-photon absorption and by heavy ions. The amplitudes and widths of the SETs were found to depend on a number of different factors, including bias conditions, strike location, and material quality. [ABSTRACT FROM PUBLISHER]

Focused, pulsed laser-light is used to investigate single-event latchup in an analog-to-digital converter (AD9240) through the generation of charge collection spectra and their dependence on bias, laser pulse intensity and strike location. Large bipolar single-event transients were identified as precursors to latchup. They occurred at bias voltages just below the latchup holding voltage and in regions that became sensitive to single-event latchup at voltages above the holding voltage. Charge collection spectra obtained from spatial scans involving the pulsed laser had features similar to those obtained from heavy-ion irradiation. Both approaches indicated enhanced charge collection at supply voltages just below the holding voltage. [ABSTRACT FROM PUBLISHER]

Single-event transient (SET)-hardened SiGe HBT RF single-pole single-throw (SPST) switches were designed and fabricated for the first time. TCAD-based heavy-ion simulations and two-photon absorption (TPA) laser-induced beam experiments were used to optimize the switch core configuration for SET mitigation. Among different configurations, the reverse-connected series and shunt device core, where both emitter terminals are connected to the output, exhibits the smallest transient peaks and shortest durations at the output terminal of the switch. Based on this finding, the design considerations for maximizing the RF performance of SiGe HBT SPST RF switches are discussed. In addition, a comparison of the SET response and RF performance of CMOS (nFET) SPST and SiGe HBT SPST switches provides additional information on the trade-offs in the SET mitigation strategy and potential RF capabilities. [ABSTRACT FROM PUBLISHER]

This paper investigates single-event effects in a W-Band (75-110 GHz) SiGe HBT down-conversion mixer intended for use in a space-based remote sensing radar system. Transient pulse propagation to the output of the mixer as a linear time variant system is analyzed theoretically. This study facilitates the understanding of transient propagation in RF receivers. Device- and circuit-level simulations were conducted to verify the results of the proposed theory. A two photon absorption laser was used to induce transients on different SiGe HBTs within the circuit to assess the impact of SETs on performance. This study shows that significant transients can be produced at the output of the mixer, which can potentially corrupt the received data or received pulse of the radar. It is shown that a differential double-balanced structure can effectively eliminate some of the transients at the output of the mixer. To the authors’ best knowledge this is the first study of single event transients conducted on a millimeter-wave SiGe circuit. [ABSTRACT FROM PUBLISHER]

Carrier-density distributions generated via two-photon absorption from pulsed laser excitation are simulated using nonlinear-optical beam propagation software. These simulated carrier-density distributions are used to calculate depth profiles of the integrated collected charge using a rectangular-parallel-piped approach for two silicon diodes of different structure. Using a set of proposed correlation metrics, the resulting simulated charge collection profiles are found to exhibit good agreement with measured transient charge-collection data for most, but not all of the metrics. The physical phenomena underlying the correlation metrics are discussed in detail. The remaining discrepancies that exist between the simulated and experimental results are addressed and their potential causes are detailed. [ABSTRACT FROM PUBLISHER]

This paper presents the impact of ion angle on the single-event latuchup (SEL) cross section with the aim of improving the interpretation of latchup cross section obtained during heavy-ion experiments and the consequences on the latchup sensitivity for parts operating in the quasi-isotropic space radiation environment. First, latchup cross sections obtained from heavy-ion beams are presented and discussed. Then, the electrical I–V measurements are presented that lead to calibration of the TCAD structure and electrical latchup model implemented in MUSCA SEP3 tool. The TCAD simulations highlight the impact of both angle and roll effects on the latchup sensitivity induced by the asymmetric layout dependence of the parasitic latchup circuit. An LET dependence of the impact of angles on the latchup sensitivity has been demonstrated. Finally, the consequences of the angular distribution of the space radiation environment on the in-orbit latchup rate are discussed. The results show that the angular analysis would be necessary if the latchup rate at normal incidence were borderline or higher than acceptable for the specifications of the space mission. [ABSTRACT FROM PUBLISHER]

The single event effect (SEE) response of devices and differential pairs in a 32-nm SOI CMOS technology is explored using laser-induced carrier injection and TCAD simulations. Both nFETs and pFETs in this technology exhibit similar sensitive area to laser-induced SEE and are strongly dependent on the drain bias condition. TCAD simulations were conducted in order to confirm results and utilize a 3-D mixed-mode simulation approach to more accurately model testing conditions. The differential pair (diff. pair) circuit SEE response extends the discussion to include the use of these devices in a core analog/RF circuit block. The analysis includes the use of floating body (FB) and body-connected (BC) devices. Body-connected FETs tend to exhibit a transient response that is much shorter in duration when compared directly to its floating body counterpart. [ABSTRACT FROM PUBLISHER]

The effects of negative feedback, both external and internal, on single event transients (SETs) in SiGe HBT analog circuits are investigated. In order to examine internal negative feedback effects, basic common-emitter NPN current mirrors, with and without emitter degeneration resistors, are utilized. A Wilson current mirror and a Wilson mirror with its intrinsic external feedback removed are used to study external negative feedback effects under the influence of laser-induced single events. The measurement data clearly show notable improvements in SET response that can be made by employing both internal and external negative feedback. The peak transient in the output current is reduced, and the settling time upon a laser strike is shortened significantly by negative feedback. All four investigated current mirrors were fabricated with IBM 8HP 130 nm SiGe BiCMOS technology. [ABSTRACT FROM PUBLISHER]

Numerical simulation software is used to calculate quantitatively the two-photon absorption-induced carrier-density distributions generated under conditions that are experimentally relevant for single-event effects studies. The results provide valuable insight into how the magnitudes and shapes of the charge carrier distributions evolve over a large range of experimental conditions and the impacts this has for different device geometries. Furthermore, values of integrated charge are determined that can be more directly correlated with experimental observables. [ABSTRACT FROM AUTHOR]

Ultraviolet optical pulses with a full-width-at-half-maximum diameter focused spot size of 0.32~\mu\m are generated, characterized, and used to produce SEUs in a 90 nm CMOS/SOI SRAM. The results provide unequivocal experimental evidence for cell-to-cell variations in SEU sensitivity that can be identified with process variations at the individual transistor level. [ABSTRACT FROM PUBLISHER]