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The impact of 63.3 MeV proton and 10 keY x-ray irradiation on the DC and AC performance of complementary (npn + pnp) 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. Index Terms--C-SiGe, heterojunction bipolar transistors, radiation effects, SiGe HBT, silicon-on-insulator, SOI, TCAD.

The radiation tolerance of strained Si/SiGe n-MODFETs is investigated, using 10 keV X-rays, 63 MeV high energy protons, and 4 MeV low energy protons. The effects of radiation exposure on two major device design parameters ([L.sub.SD] and [L.sub.G]) in T-gate Si/SiGe n-MODFETs devices are examined. A strong dependence on source-drain spacing is observed for both the DC and RF characteristics. A drift-diffusion TCAD framework is used for 2-D device simulations. We believe that the low energy protons damage the SiGe/strained-Si/SiGe lattice, leading to partial strain relaxation. The conduction band-offset (CBO) of the strained SiGe/Si heterojunction is lowered leading to higher gate current leakage. The presence of radiation-induced bulk traps in the unrelaxed SiGe layers on the device behavior is also investigated. Index Terms--Bulk traps, buried-channel, displacement damage, MODFET, radiation effects, SiGe, silicon-germanium, strain.

Using mixed-mode annealing to help evaluate the responses of modern bipolar transistors, we compare the damage processes associated with X-ray irradiation-induced and hot carrier-induced damage in SiGe HBTs. Stress and radiation measurements indicate that the by-products of both X-ray irradiation-induced and hot carrier-induced trap reactions are identical. We use calculations to better understand the operative damage mechanisms, and find that a hydrogen reaction-diffusion model can predict the observed characteristics of our measurements. Calculations indicate that the transport of hydrogen molecules inside the emitter-base oxides determines the trap generation and recovery processes. Index Terms--Mixed-mode anneal, mixed-mode stress, reaction-diffusion model, SiGe, SiGe HBTs, silicon-germanium, thermal anneal, X-ray irradiation.

The inverse mode performance of four distinct generations of SiGe HBTs is investigated and is found to improve impressively with generational scaling. Results show that the improved inverse mode performance with scaling would allow for improved design flexibility and could potentially be use to design novel circuits where speed is not the major driving factor.

The off-state drain current leakage characteristics of 130 nm CMOS technology are investigated using x-ray irradiation and operating temperature as variables. Radiation-induced interface traps in the gate oxide to gate-drain overlap region strongly enhance the off-state leakage as a function of gate bias. Due to the thin gate oxide in these 130 nm devices, we find that drain-edge direct tunneling is more plausible than conventional gate-induced-drain-leakage in explaining the observed increase in drain leakage. Radiation-induced traps in the shallow trench isolation oxide create parasitic channels in the p-well and produce another source of off-state drain leakage with increasing total dose. The drain current increase from both the gate overlap region and the shallow trench edge are enhanced with increasing total dose and suppressed by cooling. Index Terms--CMOS, cryogenic, GIDL, off-state leakage current, shallow trench isolation, STI, total dose radiation effects.

The radiation tolerance of strained Si/SiGe n-MODFETs is investigated, using 10 keV X-rays, 63 MeV high energy protons, and 4 MeV low energy protons. The effects of radiation exposure on two major device design parameters (LSD and LG) in T-gate Si/SiGe n-MODFETs devices are examined. A strong dependence on source-drain spacing is observed for both the DC and RF characteristics. A drift-diffusion TCAD framework is used for 2-D device simulations. We believe that the low energy protons damage the SiGe/strained-Si/SiGe lattice, leading to partial strain relaxation. The conduction band-offset (CBO) of the strained SiGe/Si heterojunction is lowered leading to higher gate current leakage. The presence of radiation-induced bulk traps in the unrelaxed SiGe layers on the device behavior is also investigated. [ABSTRACT FROM AUTHOR]

Using mixed-mode annealing to help evaluate the responses of modern bipolar transistors, we compare the damage processes associated with X-ray irradiation-induced and hot carrier-induced damage in SiGe HBTs. Stress and radiation measurements indicate that the by-products of both X-ray irradiation-induced and hot carrier-induced trap reactions are identical. We use calculations to better understand the operative damage mechanisms, and find that a hydrogen reaction-diffusion model can predict the observed characteristics of our measurements. Calculations indicate that the transport of hydrogen molecules inside the emitter-base oxides determines the trap generation and recovery processes. [ABSTRACT FROM AUTHOR]

The off-state drain current leakage characteristics of 130 nm CMOS technology are investigated using x-ray irradiation and operating temperature as variables. Radiation-induced interface traps in the gate oxide to gate-drain overlap region strongly enhance the off-state leakage as a function of gate bias. Due to the thin gate oxide in these 130 nm devices, we find that drain-edge direct tunneling is more plausible than conventional gate-induced-drain-leakage in explaining the observed increase in drain leakage. Radiation-induced traps in the shallow trench isolation oxide create parasitic channels in the p-well and produce another source of off-state drain leakage with increasing total dose. The drain current increase from both the gate overlap region and the shallow trench edge are enhanced with increasing total dose and suppressed by cooling. [ABSTRACT FROM AUTHOR]

Inverse-mode (collector-up) operation is proposed as a solution to the single-event-upset susceptibility observed in commercially available bulk silicon-germanium heterojunction bipolar transistors. Inverse-mode performance optimization techniques, which require no process changes or added lithographic masks, are demonstrated, yielding inverse-mode transistor performance capable of supporting gigabit-per-second digital logic needed in space-based communication systems. [ABSTRACT FROM AUTHOR]