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BIPolar Standards – BIPS

Submission summary

Since the middle of the 1970s, the harsh effect of the natural radiation environment on the on-board electronic components in satellite is known. Two main failure effects have been observed. The first one is related to the dose effects, corresponding to a slow degradation of the devices electrical parameters. There are due to charges trapping in the oxides. The second one is related to the single events, due to a single energetic particle, which is able to induce a parasitic current in a device. In this proposal, we will focus on the dose effects. This kind of degradation was considered during a long time only for MOS technologies. Since the degradation mechanism is due to the oxide charges trapping, it was generally accepted that such an effect can not be at play in bipolar technologies. The dose effect for bipolar devices is a recent challenge and it is particularly due to dose rate effect corresponding to the speed at which the dose is accumulated in a material. It is only in 1991, that the first low dose rate experiments have shown that the bipolar devices degradation can be larger than the one observed at high dose rates. It is crucial to note that, dose rates in a space environment are very low, around 10-6 Gy/s whereas testing at ground level is realized with dose rate higher than 10-2 Gy/s in order to save time. This result has a direct impact on the evaluation of devices intended to space applications since ground testing underestimate on-board degradation. In order to propose suitable testing methodologies, one must understand the physical phenomenon at play during low dose rate irradiation. In 2006, we have proposed a physical model which is the only one able to explain all the experimental data published in the literature. This model is based on charges trapping and recombination in the oxide. It has emphasized the important part of both the internal electric field and oxide quality. In order to observe the dose rate effect, the internal electric field must be low enough and the quality of the oxide must be poor. For bipolar technologies, these two criterions are often encountered, particularly in passivation oxides. Moreover, many others electronic and optoelectronic devices have the same characteristics. The proposed model allows then to tackle the dose rate effect problematic on all oxide-based components. Therefore, the aim of our work is to define testing methods in order to predict the degradation of electronic and optoelectronic devices intended to a low dose rate environment. The problematic is to succeed in predicting the degradation of a fifteen-years on-board device from a one-month ground test. We propose then a plan structured around four points: • The experimental validation of the physical model. • A modelling of the physical mechanisms at play from the irradiation to the characteristic parameters of the device degradation. • The proposal of testing methods for bipolar devices intended to space applications. • The evaluation of dose rate effect on other devices with oxide subjected to low electric fields, particularly BiCMOS devices and optical fibers, which will be on-board very soon. In long term, the aim of our team is to give to space manufacturers an expertise in hardness assurance method to devices intended to harsh radiative environment thanks to our competence in both electronic and optoelectronic devices in order to define new European standards.

Project coordination

Jérôme BOCH (Université)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.



Help of the ANR 188,860 euros
Beginning and duration of the scientific project: - 48 Months

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