Relationship between ion track characteristics and single event transients in nanometer inverter chain

Abstract

Ions with the same linear energy transfer (LET) value, but different energies and species have various ion track characteristics, and thus induce different single event transient (SET) responses in combinational logics. As the technology feature size shrinks, this issue continues to be serious. The research of the relationship between ion track characteristics and SETs in the nanometer combinational logic circuits is of great significance for accurately predicting the soft error rates of nanometer devices used in spacecraft. The combinational logic circuit investigated in this paper is a 65 nm bulk silicon complementary metal oxide semiconductor (CMOS) technology inverter chain. The three-dimensional TCAD model of the inverter chain is established, and the particle transport program for the ion track in bulk silicon is developed by Geant4. The track characteristics of high- and low-energy ions (the energy of low-energy ions is less than 10 MeV·n<sup>–1</sup>, the energy of high-energy ions ranges from tens of MeV·n<sup>–1</sup> to hundreds of MeV·n<sup>–1</sup>) which have the same LET value are compared with each other. Based on the coupled simulation of TCAD and Geant4, the difference in SET pulse widths, induced by ions with the same LET value but different energies, are investigated. It is found that when the energy per nucleon ratio of high-energy ion to low-energy ion increases, the difference in electron-hole pair densities near the center axis of the ion track is more significant, and thus the difference in SET pulse widths is larger. If the energy per nucleon ratio is similar, raising the LET value of ions can increase the difference in electron-hole pair densities on the same radial scale of the ion tracks, and make the SET pulse width difference more obvious. For the high- and low-energy ions with the same LET value, the single event charge generations are different. On the other hand, the change of the ion incident angle results in different charge collections. The coupling of these two factors makes the difference in SET pulse widths dependent on the incident angle of ions. In addition, the influence of ion track characteristics on SET has a weak correlation with the bias voltage of the inverter chain.