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The total-ionizing-dose response of third-generation SiGe HBTs was investigated at elevated temperatures (80 °C and 130 °C) and compared with the response at 30 °C. The devices show less damage to irradiation at higher temperatures. Annealing experiments and TCAD simulations are used to investigate the degradation mechanism. The reduced degradation in forward mode at elevated temperatures is caused by increased annealing of interface traps primarily due to diffusion and reactions of H2 within the oxide/nitride EB spacer. The degradation is modest at all measured temperatures, allowing these devices to be suitable for radiation-rich environments where elevated temperatures are expected. [ABSTRACT FROM AUTHOR]

Integrated silicon microwave pin diodes are exposed to 10-keV X-rays up to a dose of 2 Mrad(SiO2) and 14-MeV fast neutrons up to a fluence of $2.2\,\,\boldsymbol {\times }\,\,10\,\,^{\mathrm{ 13}}$ cm−2. Changes in both dc leakage current and small-signal circuit components are examined. Degradation in performance due to total-ionizing dose (TID) is shown to be suppressed by non-quasi-static (NQS) effects during radio frequency (RF) operation. Tolerance to displacement damage from fast neutrons is also observed, which is explained using technology computer-aided design (TCAD) simulations. Overall, the characterized pin diodes are tolerant to cumulative radiation at levels consistent with space applications such as geosynchronous weather satellites. [ABSTRACT FROM AUTHOR]

Statistical analysis is performed on the totalionizing-dose (TID) response of fourth-generation silicon–germanium heterojunction bipolar transistors, revealing an increasing variance in base current with increasing dose. A 10-fold increase is observed after 2 Mrad(SiO2) of radiation exposure. The postirradiation performance is shown to be poorly correlated with initial performance, revealing potential difficulties for radiation hardness assurance testing. Simple analytical theory is used to demonstrate how TID exacerbates performance variations due to preexisting process-induced variations. Then, technology computer-aided design (TCAD) simulations are used to investigate the fundamental mechanisms driving these statistical changes, particularly process variations associated with the doping profiles. Simulation results reveal potential methods to both predict TID response and mitigate it at the process level. Finally, implications for hardness assurance testing and radiation-tolerant device and circuit design are discussed, especially the need to consider postirradiation variability in the design process for radiation-intense applications. [ABSTRACT FROM AUTHOR]

Low-noise amplifiers (LNAs) are necessary components for any communications system. Single-event transients (SETs) induced by energetic particles in space can corrupt the data in an RF receiver. Using p-n-p silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs), instead of their more common n-p-n counterparts, has been shown to be an effective mitigation technique in digital, analog, and RF circuits. Since p-n-p SiGe HBTs tend to have lower performance than n-p-n SiGe HBTs, in this article, the tradeoffs between performance and SET robustness have been evaluated through the use of simulations. Two LNAs were designed using an algorithmic design technique: one using only n-p-n SiGe HBTs, and the other using only p-n-p devices. The n-p-n LNA had higher peak gain and lower noise figure at the center frequency of 5 GHz when compared to the p-n-p LNA, by 3.2 and 0.4 dB, respectively. However, the n-p-n LNA also produced transients with amplitudes larger than the p-n-p LNA across all simulated linear energy transfers. Although the p-n-p LNA has lower overall performance, it is also more robust to SETs. Thus, the choice between using n-p-n and p-n-p SiGe HBTs for an RF design will depend on application requirements. [ABSTRACT FROM AUTHOR]

A comparison of heavy-ion-induced single-event transients (SETs) in silicon–germanium heterojunction bipolar transistors (SiGe HBTs) fabricated on both bulk and silicon-on-insulator (SOI) substrates is presented. Experimental heavy-ion data show a reduction of sensitive volume of ≈ 350 × for the SiGe HBTs fabricated on SOI compared to those on a bulk substrate. Furthermore, the results indicate that the sensitive volume of the SOI SiGe HBTs is confined to the intrinsic device. These results have been confirmed using pulsed laser data and TCAD simulations. Limiting the charge collection depth of SiGe HBTs by fabricating them on SOI facilitates correlation of ion and laser results. The improved ease of correlation is a result of suppressing diffusive charge collection mechanisms that are difficult to replicate with the charge deposition profile generated by two-photon absorption using a tightly focused laser beam. However, a potential issue with pulsed laser testing is determining the loss of the pulse energy through the buried oxide, which requires detailed knowledge of the semiconductor platform. Overall, the reduction of sensitive volume for the SOI SiGe HBTs compared to those on a bulk substrate is a clear advantage from a single-event upset vulnerability perspective. [ABSTRACT FROM AUTHOR]

The propagation of single-event transients from the electrical to the photonic domain in a segmented Mach–Zehnder modulator was investigated using pulsed-laser measurements and lumerical simulations. Although electrical transients can heavily degrade the input data to the modulator, almost all of the degradation can be suppressed once it is converted into the optical domain. The mitigation of transients is primarily accomplished by increasing Vπ of each segment, making electrical transients up to 6 V essentially negligible. A “folding” effect of the optical transient is also explained in relation to Vπ. Two radiation-hardening-by-design (RHBD) approaches are suggested to mitigate transient effects. [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]

The doping profile of silicon-germanium heterojunction bipolar transistors (SiGe HBTs) is modified to enhance inverse-mode (IM) device operation. Device improvements are presented in this paper, along with the impact the alterations have on the radiation effects response. This investigation represents the first published occurrence of a radiation-hardening-by-process approach in a SiGe HBT technology. Results show that improving IM performance can degrade the radiation tolerance of the structure. Total ionizing dose and single-event transient (SET) results are provided along with an analysis that utilizes TCAD simulation. An additional profile modification using an implanted vertical superjunction is included in this paper to expand upon how nonradiation specific device modifications can impact SETs. [ABSTRACT FROM PUBLISHER]

The single-event upset response of SiGe-based digital circuits designed in a third-generation, bulk C-SiGe (npn + pnp) BiCMOS platform is investigated. Heavy-ion, broad-beam experiments across data rate, incidence angle, and bit stream pattern show that the pnp-based shift registers exhibit significant reductions in error cross section when compared with npn-only designs. Ion-strike simulations using 3-D TCAD models agree with the experimental findings, where the pnp SiGe heterojunction bipolar transistor (HBT) exhibits reduced sensitive area and transient duration, leading to large reductions in collected charge at the collector (output) terminal. The circuit-level, heavy-ion measurements are in agreement with previous device-level, pulsed-laser studies, where the single-event effect (SEE) improvement of pnp SiGe HBTs was attributed to the n-well isolation layer present in the vertical material stack of the pnp SiGe HBT structure. These results provide confirmation that precision analog, RF/mm-wave, and high-speed digital applications utilizing unhardened, high-performance bulk pnp SiGe HBTs should benefit from an inherently improved SEE response. [ABSTRACT FROM PUBLISHER]

This paper demonstrates the use of an RF power detector to sense the occurrence of single-event transients (SETs) in RF circuits and systems. The detector was connected to a low-noise amplifier (LNA), and the relationship between the detector output and the LNA transients was investigated via two-photon absorption, pulsed-laser testing, together with mixed-mode TCAD simulations. The response of the detector shows a strong correlation with the RF power of the generated SET. An analytical expression for the detector output is derived and utilized to fit the data. The effects of parameters affecting circuit performance on the detector response to SETs are explored using calibrated TCAD mixed-mode simulations, and design tradeoffs are presented. Finally, a solution to distinguish between transients generated in the detector from those generated in the circuit being monitored is proposed and verified in simulation. The use of detectors to monitor SETs in RF systems could lead to judicious deployment of detection-driven SET mitigation techniques. [ABSTRACT FROM PUBLISHER]

The propagation of single-event transient (SET) signals in a silicon–germanium direct-conversion receiver carrying modulated data is explored. A theoretical analysis of transient propagation, verified by simulation, is presented. A new methodology to characterize and quantify the impact of SETs in communication systems carrying modulated data is proposed. The proposed methodology uses a pulsed radiation source to induce distortions in the signal constellation. The error vector magnitude due to SETs can then be calculated to quantify errors. Two different modulation schemes were simulated: QPSK and 16-QAM. The distortions in the constellation diagram agree with the presented circuit theory. Furthermore, the proposed methodology was applied to evaluate the improvements in the SET response due to a known radiation-hardening-by-design (RHBD) technique, where the common-base device of the low-noise amplifier was operated in inverse mode. The proposed methodology can be a valid technique to determine the most sensitive parts of a system carrying modulated data. [ABSTRACT FROM PUBLISHER]

Best practice in mitigation strategies for single-event transients (SETs) in radio-frequency (RF) receiver modules is investigated using a variety of integrated receivers utilizing inverse-mode silicon–germanium (SiGe) heterojunction bipolar transistors (HBTs). The receivers were designed and implemented in a 130-nm SiGe BiCMOS technology platform. In general, RF switches, low-noise amplifiers (LNAs), and downconversion mixers utilizing inverse-mode SiGe HBTs exhibit less susceptibility to SETs than conventional RF designs, in terms of transient peaks and duration, at the cost of RF performance. Under normal RF operation, the SET-hardened switch is mainly effective in peak reduction, while the LNA and the mixer exhibit reductions in transient peaks as well as transient duration. [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]

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 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]

Total ionizing dose (TID) effects are evaluated for a high-voltage (>30 V) complementary SiGe on SOI technology. Devices are irradiated with 10-keV X-rays at doses up to 5 Mrad(SiO2). The results depend strongly on collector-to-emitter bias, in both forward- and inverse-mode. An anomalous reduction in current gain at high injection in forward-mode operation is observed at doses >500 krad(SiO2). Calibrated 2-D TCAD simulations suggest that this high injection phenomenon is primarily due to interface traps near the STI/Si interface, which is exhibited as a collector resistance increase in the forward Gummel characteristics. Additionally, a strong collector doping dependence is observed, which indicates that this is primarily driven by the thick and lightly doped collector used in this technology. These results illustrate, that high concentrations of interface traps at the STI can have a strong impact on the forward-mode TID response of SiGe HBTs. [ABSTRACT FROM PUBLISHER]

This paper presents the design and thorough on-wafer characterization of two G-band low-noise amplifiers (LNAs) implemented using 0.13- \mu \textm silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) with peak fT/f\max of 300/500 GHz. The impact of the substrate network and optimized via interconnections on the SiGe HBT performance is investigated to ensure that maximum performance is extracted from each SiGe HBT. The two LNAs are separately implemented using only cascode pairs and only common-emitter (CE) SiGe HBTs to determine which configuration yields better performance in a multistage G-band LNA. The cascode LNA achieves a peak gain of 24.0 dB at 158 GHz with a mean noise figure (NF) of 8.2 dB from 145 to 165 GHz, while the CE LNA achieves a 17.2 dB of gain at 183 GHz with a mean NF of 8.0 dB across 165–200 GHz. A novel implementation of blackbody noise sources for on-wafer Y-factor NF measurements reduces the waveguide length needed to transition between the antenna and the probe, which significantly reduces the sensitivity to jitter. To the authors’ knowledge, these LNAs achieve the lowest reported NF of all SiGe LNAs at these frequencies to date, and the results demonstrate that SiGe HBTs are viable options for millimeter-wave performance-constrained applications. [ABSTRACT FROM PUBLISHER]

The single-event transient (SET) response of a SiGe-based, L-band low-noise amplifier (LNA) is investigated, with a focus on providing recommendations for radiation event simulation techniques. Pulsed-laser, two-photon absorption experiments show that the SET sensitivity of the SiGe LNA is highly dependent on operating conditions and strike location. Time and frequency-domain analyses raise potential concerns for digital data modulated on RF carrier signals. Device and circuit-level ion-strike TCAD simulations are utilized to compare alternative simulation approaches, highlight the importance of parasitics on SET simulation accuracy, and suggest best practices for modeling radiation-induced transients within RF/mm-wave circuits. [ABSTRACT FROM AUTHOR]

Large-signal (P1dB ) and small-signal (OIP3) radio frequency (RF) linearities of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) fabricated in a new fourth-generation 90-nm SiGe BiCMOS technology operating at cryogenic temperatures are investigated. The SiGe BiCMOS process technology has an ƒT/ƒmax of 300/350 GHz. SiGe HBTs with two different layout configurations, collector-base-emitter (CBE) and CBE-base-collector (CBEBC), were characterized over temperature. Both dc and ac figures-of-merit are presented to aid in understanding the linearity, and to provide an overall performance comparison between the two layout configurations. The extracted peak ƒT/ƒmax for CBE and CBEBC at 78 K are 387/350 and 420/410 GHz, respectively. The P1dB and OIP3 linearity metrics for both configurations are comparable. Source- and load-pull measurements were performed at each temperature at 8 and 18 GHz, with the devices biased at a JC of 18 mA/μm2. Two-tone measurements over bias were also performed at 300 and 78 K with 50-Ω terminations for the source and load impedances. The 50 Ω results follow a similar response to the source- and load-pull measurements at 300 and 78 K, and demonstrate that the small-signal linearity of the SiGe HBTs is not adversely impacted by operation at cryogenic temperatures. The CBEBC configuration demonstrated the most consistent RF linearity performance at cryogenic temperature out of the two layout options. [ABSTRACT FROM PUBLISHER]