Proton Direct Ionization in Sub-Micron Technologies: Numerical Method for RPP Parameter Extraction

This work introduces a numerical method to iteratively extract parameters of a rectangular parallelepiped (RPP) sensitive volume (SV) from experimental proton direct ionization (PDI) SEU data. The method combines two separate numerical models. The first model estimates the average linear energy transfer (LET) values for energetic ions, including protons and also heavy ions, in elemental solid targets. The second model describes the statistical variance in the energy deposition events of projectile-induced primary ionization within an RPP-shaped target volume. To benchmark the method, simulated cross section values based on RPP parameters derived with this method are compared with the literature data from four SRAM devices. The RPP geometries determined by this method reproduced the experimental cross section values in the literature with good accuracy, therefore showing that this method can be used to reliably and quickly determine the RPP parameters for SVs in memories sensitive to PDI. The method is currently strictly limited to direct ionization effects, i.e., not taking into account any nuclear reaction mechanisms, and elemental materials due to the underlying models’ definitions.