Failure tests on 64 Mb SDRAM in radiation environment

In this paper we analyze the failures of Commercial Off The Shelf (COTS) 64 Mb Synchronous DRAM (SDRAM) in a radiation environment. The experimental setup, the test procedure, and the results of three different test runs at the Catania LNS-INFN cyclotron are described in some detail. Three kinds of heavy ions were used to test devices under different conditions of energy release that generates different amount of charge inside the chip. In particular, 30 MeV/AMU /sup 93/Nb (LET/sub Si//spl sim/21 MeV/(mg/cm/sup 2/), R/sub Si//spl sim/397 /spl mu/m), 30 MeV/AMU /sup 120/Sn (LET/sub Si//spl sim/30 MeV/(mg/cm/sup 2/), R/sub Si//spl sim/370 /spl mu/m) and 15 MeV/AMU /sup 197/Au (LET/sub Si//spl sim/90 MeV/(mg/cm/sup 2/), R/sub Si//spl sim/95 /spl mu/m) were used. In all cases, the bare dies were directly bonded on an AF4 carrier to avoid plastic and lead-frame shielding. Different failure types that could affect the operations of a system based on this device were registered. To verify that the characteristics of the events depend on the zone struck by the particle, a specific test was performed.