Heidi N. Becker

Latent damage in CMOS devices from single-event latchup

Evaluation of several types of CMOS devices after nondestructive latchup revealed structural changes in interconnects that appears to be due to localized ejection of part of the metallization due to melting. This is a potential reliability hazard for CMOS devices because it creates localized voids within interconnects that reduce the cross section by one to two orders of magnitude in the damaged region. These effects must be considered when testing devices for damage from latchup, as well as in establishing limits for current detection and shutdown as a means of latchup protection.

Displacement damage-induced catastrophic second breakdown in silicon carbide Schottky power diodes

A novel catastrophic breakdown mode in reverse biased silicon carbide diodes has been seen for particles that are too low in LET to induce SEB, however SEB-like events were seen from particles of higher LET. The low LET breakdown mechanism correlates with second breakdown in diodes due to increased leakage and assisted charge injection from incident particles. Percolation theory was used to predict some basic responses of the devices.

Dark current degradation of near infrared avalanche photodiodes from proton irradiation

InGaAs and Ge avalanche photodiodes (APDs) are examined for the effects of 63-MeV protons on dark current. Dark current increases were large and similar to prior results for silicon APDs, despite the smaller size of InGaAs and Ge devices. Bulk dark current increases from displacement damage in the depletion regions appeared to be the dominant contributor to overall dark current degradation. Differences in displacement damage factors are discussed as they relate to structural and material differences between devices.

The influence of structural characteristics on the response of silicon avalanche photodiodes to proton irradiation

Different silicon avalanche photodiode structures are compared for the effects of 51-MeV protons on dark current, photocurrent, and noise. Large differences in depletion region volumes contributed to differences in sensitivity to bulk dark current increases. At high fluences, ionization damage appeared to be the dominant mechanism for dark current increases in some devices. Increases in 1/f-type noise and supplemental gamma ray testing indicate that these high dark current increases are due to surface damage effects. A discussion of structural parameters that may heighten radiation sensitivity is presented, including doping levels and p-n junction termination techniques.

Catastrophic latchup in CMOS analog-to-digital converters

Heavy-ion latchup is investigated for analog-to-digital converters. Differences in cross section for various ions show that charge is collected at depths beyond 50 /spl mu/m, causing the cross section to be underestimated unless long-range ions are used. Current distributions, thermal imaging, and diagnostic tests with a pulsed laser were used to identify latchup-sensitive regions. Latchup in one of the circuit types was catastrophic, even when the power was turned off within 2 ms of a latchup event. Examination of damaged devices with a scanning electron microscope showed that the failures occurred in metallization and contact regions. Current density for failure agrees with pulsed current metallization stress data in the literature.

Effects of Gamma and Heavy Ion Damage on the Impulse Response and Pulsed Gain of a Low Breakdown Voltage Si Avalanche Photodiode

Effects of displacement and ionization damage on the impulse response of a high-bandwidth low breakdown voltage Si Avalanche Photodiode was investigated using a picosecond laser system. Damage was generated using either Co60 gamma-irradiation or by scanning the device with an MeV ion microbeam. No shift in the impulse response characteristics and gain was observed for gamma doses as high as 100 kGy(Si). However, dark current measurements for irradiations with biases close to typical operating levels, exhibited enhanced ionization damage orders of magnitude higher than for no bias. Displacement damage introduced by the microbeam was used to differentiate between ionization damage in the guard ring isolation oxide and bulk damage. The absence of any marked change in the impulse response is discussed, as are possible mechanisms for the enhanced ionization damage

Radiation Response of Emerging High Gain, Low Noise Detectors

Data illustrating the radiation response of emerging high gain, low noise detectors are presented. Ionizing dose testing of silicon internal discrete avalanche photodiodes, and 51-MeV proton testing of InGaAs/InAlAs avalanche photodiodes operated in Geiger mode are discussed.

Effects of Radiation on Commercial Power Devices

The effects of radiation on various commercial power devices are presented. The devices have proved to be very fragile to single event effects, with some of the devices actually succumbing to catastrophic SEE with protons

Qualification and reliability testing of a commercial high-power fiber-coupled semiconductor laser for space applications

A compact microchip laser pumped by a single fiber-coupled semiconductor diode laser is developed for a space-borne scanning laser radar instrument. A commercial off-the-shelf component is used for the pump laser and undergoes a rigorous qualification approach to meet the requirements for the space-borne application. The qualification and testing process for the commercial pump laser is derived based on a nonstandard piece part screening plan and is presented along with the test results. These tests include mechanical, vibration, thermal cycling, and radiation tests as well as a full destructive parts analysis. Accelerated lifetests are also performed on the packaged device to demonstrate the ability to meet an operational lifetime of 5000 h. The environmental testing approach would be applicable to space qualification of a variety of commercial photonic systems, particularly in cost-constrained missions.

Degradation of InP-based Geiger-mode avalanche photodiodes due to proton irradiation

Degradation of InGaAs/InP Geiger-mode avalanche photodiodes caused by proton irradiation is reported for the first time. The devices are found to be very sensitive to displacement damage. Substantial changes in the dark count rate, and the after-pulse count rate are observed following room temperature irradiation and characterization at −50°C. The device detection efficiency is unaffected by irradiation. Following 51 MeV proton fluences in the mid 109 protons/cm2 range, the dark count rate becomes so large that the devices are rendered essentially unusable. This is a very low fluence at which to observe device failure.