The laser-only single-event effects test method for space electronics based on ultrashort-pulsed-laser 'local irradiation'

Abstract

The advances of the picosecond and femtosecond laser installations utilization for radiation hardness evaluation of semiconductor electronics for space applications are presented. The modern “local laser irradiation” method for single event effects testing of semiconductor devices, not requiring calibration by ions is described. The essence of the local approach is in irradiating the sample sensitive volume, positioned at some distance from the focus plane, where the beam becomes divergent. Due to such optical effects as single or multiple reflections, scattering, diffraction, reflections from air-SiO2 boundary, interference, absorption in n+/p+/poly-Si layers and reflection from bottom side of substrate, the laser light partially penetrates into the sensitive volume, screened by the presence of multilayer metallization,n+/p+ nearsurface layers, regions of polysilicon in the passivation layer, etc. Assuming single-photon absorption the relationship between the laser pulse energy and the excess charge actually generated in irradiated sensitive volume is obtained by the measurement of the electrical response, thus taking into account the non-uniform optical losses and avoiding additional calibration by ions. Some results, obtained using both the front-side and the backside local irradiation of devices, are presented. Comparison with the results obtained using focused laser radiation with subsequent calibration by ions showed that the laser-only measurements, based on local irradiation, give the correct estimates of radiation hardness parameters. It is shown that the use of backside local irradiation method is the most suitable for laser single event effects tests.