Ion beam testing of SRAM-based FPGA´s

We have investigated the effects produced by exposing a field programmable gate array (FPGA) based on static RAM to an ion beam. Tested devices have been taken from FLEX10K family manufactured by Altera Corporation. These parts are commercial graded and not qualified for application in radioactive environments. A design based on mixed plain and triple-modular-redundant (TMR) shift registers (SR´s) has been implemented in the FPGA under test. No single event upset (SEU) was detected in the shift registers. The predominant effect of irradiation with heavy ions was the single event functional interrupt (SEFI). SEFI´s have been induced from SEU´s in the configuration memory. No destructive latch-up has been observed. During irradiation, supply current has been observed to increase almost linearly with ion fluence, probably due to progressive SEU-induced driver contentions. The configuration memory cross section has been calculated and we have found the saturation level of 2.5·10^-8 cm² /bit reached with LET>40 MeV·cm²/mg.