Abstract
In the harsh environment of space, high energetic particles are the source of many radiation effects which can not only degrade but also alter electrical components onboard spacecraft. As a result of inflight observations of the CARMEN experiment and the PICARD satellites star tracker’s memory, a new type of error with unique characteristics, called weakened cells (or Intermittent Stuck Bit - ISB), has been observed. On the DRAM memory, this error occurred repeatedly at the same addresses, being persistent during power cycles of the device and randomly stuck/unstuck over time. While many studies suggest that displacement damages is the root cause, the main mechanisms in place are still under debate. This thesis, supported by CNES and TRAD company, has been carried out to study the phenomenon on DRAM devices, through both experiment and simulation. The inflight reference as well as new ones from different manufacturers were tested on the ground level under proton and heavy ions irradiation. Experimental results at the component level showed that the coupled effect of a damaged cell with a faulty DRAM refresh operation can lead to unexpected error behaviors. Meanwhile, TCAD simulations with ECORCE software provided more details on the underlying physical mechanisms at the single DRAM’s cell level. The 2D model of the transistor accessed under single and combined radiation effects showed a dramatic increase in leakage current in the damaged cell, which is the main cause of the retention time degradation. Finally, the coherence between the two was joined to give a projection of future trends.