Naomi Ikeda

Anomalous Charge Collection in Silicon Carbide Schottky Barrier Diodes and Resulting Permanent Damage and Single-Event Burnout

It was demonstrated that Silicon Carbide Schottky Barrier Diodes exhibited anomalous charge collection with heavy ion irradiation. Consequently, the permanent damage and Single-Event Burnout was observed in spite of no known current sustaining mechanism. A model for the mechanism was proposed based on the device simulation

Single-Event Damages Caused by Heavy Ions Observed in AlGaN/GaN HEMTs

It was demonstrated that several kinds of permanent damage were introduced by heavy ions in AlGaN/GaN HEMTs similar to SiC devices. A new mode of damage attributable to the transistor structure was also identified in addition to the damage observed similarly in SiC devices.

Characterization of Microdose Damage Caused by Single Heavy Ion Observed in Trench Type Power MOSFETs

It was demonstrated that anomalously large degradation observed in power MOSFETs was caused by a single heavy ion. It was identified as a microdose effect and successfully characterized by several parameters extracted from the experimental data.

Improved model for single-event burnout mechanism

We describe an improved model for single-event burnout (SEB) mechanism. The model includes the direct tunneling of carriers at the interface of epitaxial layer and substrate. Compared with our previous models, the new model is more successful in reproducing the voltage dependence of the collected charge when incident heavy ions strike the emitter area. The model clearly explains the reason why the emitter stripe region was more susceptible to SEBs.

Study of Latent Damage in Power MOSFETs Caused by Heavy Ion Irradiation

The latent damages were investigated for power MOSFETs irradiated by high LET heavy ions. It was demonstrated that the post irradiation leakage current in damaged gate oxide was determined by the initial gate stress after the irradiation and the damage was stable even after a million of gate stress repetition.

Single-event burnout of Super-junction power MOSFETs

The experimental results of single-event burnout (SEB) of super-junction power MOSFETs are reported for the first time in comparison with those of standard MOSFETs. Similar tendencies were observed from both results. While a super-junction MOSFET (SJ-MOSFET) has an attractive electrical performance such as low on-resistance and high breakdown voltage, the experiment demonstrated that there was no structural advantage in SEB tolerance.

Statistical Analysis of Heavy-Ion Induced Gate Rupture in Power MOSFETs—Methodology for Radiation Hardness Assurance

A methodology for power MOSFET radiation hardness assurance is proposed. It is based on the statistical analysis of destructive events, such as gate oxide rupture. Examples of failure rate calculations are performed.

Bulk damage caused by single protons in SDRAMs

A new failure mode that is attributable to the bulk damage caused by single protons has been reported in 256-Mbit SDRAMs. The refresh rate required to retain memorized data was measured as a typical parameter to detect the effect. We performed the proton irradiation test and discussed results regarding the influence of this failure.

Evaluation of the Proton Induced Bulk Damage in SDRAM Utilizing 90 nm Process Technology

We describe proton induced bulk damage observed in 90 nm process SDRAM. The degradation of the data retention ability was evaluated. The effect due to the difference of process technology and memory cell structure was discussed. The result indicates that the value of the capacitance of the storage capacitor and the volume of the depletion region are key parameters concerning the failures caused by bulk damage.

Enhanced avalanche multiplication factor and single-event burnout

We describe experimental data for single-event burnout of bipolar junction transistors and the results of analysis using device simulators. The analysis indicates that the enhanced impact ionization rate in the ion track plays an essential role to trigger the burnout.