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We investigate the effects of both X-ray and proton irradiation on a novel 200 GHz/90 GHz (npn/pnp) complementary SiGe:C HBT technology. The DC forward mode total dose tolerance of the pnp HBTs is shown to exceed that of the npn HBTs by a significant margin after being subjected to both 63-MeV proton and 10-keV X-ray sources, while the AC characteristics of both devices exhibit no degradation up to X-ray doses as high as 1.8 Mrad(SiO2). Pre- and post-irradiation results from a current feedback operational amplifier implemented in this technology and irradiated up to a dose of 1.8 Mrad(SiO2) are presented, showing no degradation in performance metrics under two low current density bias configurations.

We have performed an experimental study of the effects of ionizing radiation and bias-temperature stress on Si MOS devices with HfSiON gate dielectrics. We compare the responses of homogeneous high-SiN films and low-SiN films that contain crystalline HfO. We observe that the low-SiN films are more sensitive to ionizing radiation than the high-SiN films. In particular, the low-SiN film that includes crystalline HfO is especially vulnerable to electron trapping due to substrate injection under positive irradiation bias. Both film types exhibit reduced radiation-induced charge trapping relative to previous Hf silicates. The high-SiN film exhibits less radiation-induced net oxide-trap charge density than earlier Hf silicate films processed without nitride. We also find that these devices are relatively robust against bias-temperature stress instabilities. Consistent with the radiation response, the low-SiN devices also display elevated levels of charge trapping relative to the high-SiN devices during bias-temperature stress.

The impact of 63.3 MeV proton and 10 keV X-ray irradiation on the DC and AC performance of complementary SiGe HBTs on thick-film SOI is investigated. Proton and X-ray induced changes in the forward and inverse Gummel characteristics, the output characteristics, and avalanche multiplication are reported for both npn and pnp SiGe HBTs, at both room temperature (300 K) and at cryogenic temperatures (down to 30 K). Comparison of room temperature and cryogenic data suggests interface trap formation at two distinct physical locations in the transistors. Experimental data and calibrated TCAD simulations are used to compare the radiation response of both thick-film SOI devices and thin-film SOI SiGe HBTs.

A comprehensive investigation of the performance dependencies of irradiated SiGe precision voltage reference circuits on (1) total ionizing dose (TID), (2) circuit topology, and (3) radiation source is presented. Two different bandgap voltage references were designed using a first-generation (50-GHz) SiGe BiCMOS technology platform, and subsequently exposed to X-rays at doses of 1080 krad(SiO2) and 5400 krad(SiO2). The degradation in circuit performance following X-ray irradiation depends on both the TID level and the chosen circuit topology. Measurement results show that large TID levels can significantly shift the magnitude of the output voltage. Explanations for the observed shifts are provided by utilizing detailed analyses of the two circuit topologies and considering device-to-circuit interactions. The primary factor responsible for the difference in the circuit response before and after irradiation can be attributed to the excess base leakage current in the SiGe HBT. To investigate the impact of radiation source, the circuit topology showing the worst-case degradation from the X-ray experiment was independently exposed to 63-MeV protons at the same effective TID level. A clear source dependence in the circuit response was observed, and possible origins of this behavior are identified.

We compare, for the first time, the effects of 63 MeV protons on 1st generation and 3rd generation SiGe HBTs irradiated at both liquid nitrogen temperature (77 K) and at room temperature (300 K). The 1st generation SiGe HBTs irradiated at 77 K show less degradation than when irradiated at 300 K. Conversely, the 3rd generation SiGe HBTs exhibits an opposite trend, and the devices irradiated at 77 K show enhanced degradation compared to those irradiated at 300 K. The emitter-base spacer regions for these two SiGe technologies are fundamentally different in construction, and apparently are responsible for the observed differences in temperature-dependent radiation response. At practical circuit biases, both SiGe technology generations show only minimal degradation for both at 77 K and 300 K exposure, to Mrad dose levels, and are thus potentially useful for electronics applications requiring simultaneous cryogenic temperature operation and significant total dose radiation exposure

X-ray total ionizing dose effects in both fully-depleted and partially-depleted SiGe HBT-on-SOI transistors are investigated at room and at cryogenic temperatures for the first time. Devices irradiated in grounded and forward-active mode configurations exhibit a different behavior depending on the collector doping of the device. The degradation produced by 10 keV x-rays is compared to previously reported 63 MeV proton results on the same fully-depleted SiGe HBT-on-SOI devices, showing decreased degradation for proton irradiation. Both collector and substrate bias are shown to affect the two-dimensional nature of the current flow in these devices, resulting in significant differences in the avalanche multiplication characteristics (hence, breakdown voltage) across temperature

We present the results of gamma irradiation on third-generation, 200 GHz SiGe HBTs. Pre- and post-radiation dc figures-of-merit are used to quantify the tolerance of the raised extrinsic base structure to Co-60 gamma rays for varying device geometries. Additionally, the impact of technology scaling on the observed radiation response is addressed through comparisons to second generation, 120 GHz SiGe HBTs. Comparisons to previous proton-induced degradation results in these 200 GHz SiGe HBTs are also made, and indicate that the STI isolation oxide of the device shows increased degradation following Co-60 irradiation. The EB spacer oxide, on the other hand, demonstrates increased susceptibility to proton damage. Low dose rate proton testing was also performed and indicate that although there is a proton dose rate effect present in these devices, it cannot fully explain the observed trends. Similar trends have previously been observed for buried oxides and isolation oxides in several MOS technologies and have been attributed to increased charge yield in these oxides for 1.2 MeV Co-60 gamma rays when compared to 63 MeV protons.

1.8 MeV proton radiation-induced degradation in high electron mobility transistors with Si-doped Al/sub x/Ga/sub 1-x/N and thick GaN cap layers is studied up to a fluence of 1/spl times/10/sup 15/ protons/cm/sup 2/. The thick GaN cap layer reduces sheet charge modulation induced by the surface states, as it electrostatically separates the active device layers from the surface, thereby enhancing the device performance. The devices exhibit good tolerance up to 10/sup 14/ protons/cm/sup 2/, with displacement damage being the primary degradation mechanism. Charged defect centers introduced by proton radiation in the active device layers degrade carrier mobility and sheet carrier density. Proton radiation alters the barrier height at the Schottky gate and increases the resistance of the thin film structure.

The degradation of AlGaN/AlN/GaN high electron mobility transistors due to 1.8-MeV proton irradiation was measured at fluences up to 3/spl times/10/sup 15/ cm/sup -2/. The devices have much higher mobility than AlGaN/GaN devices, but they possess similarly high radiation tolerance, exhibiting little degradation at fluences up to 1/spl times/10/sup 14/ cm/sup -2/. Decreased sheet carrier mobility due to increased carrier scattering and decreased sheet carrier density due to carrier removal are the primary damage mechanisms. The device degradation is observed as a decrease in the maximum transconductance, an increase in the threshold voltage, and a decrease in the drain saturation current.

The authors reported the floating body effects in 90nm partially-depleted, strained-silicon CMOS on SOI devices operating down to cryogenic temperatures. These devices also exhibit immunity to X-ray and proton irradiation without process hardening (Appaswamy et al, 2006) and thus are potentially suitable for space applications. One-to-one comparisons are made to conventional unstrained CMOS on SOI devices from the same 90 nm technology node

The effects of 63 MeV proton irradiation on 90 nm strained silicon CMOS on insulator is examined for the first time. The devices show no observable degradation in DC performance up to an equivalent total dose of 600 krad(Si). The performance of the strained pFETs is identical to unstrained pFETs and demonstrates the immunity of strain to displacement damage. There is no significant enhancement observed in back channel leakage for the maximum dose. Passive exposure to 2 Mrad(Si) using 4 MeV protons doesn't induce any significant performance degradation.