HARDNESS ASSURANCE FOR LOW-DOSE SPACE APPLICATIONS

We present a method to conservatively estimate MOS hardness in space that shares the same technical basis as MIL-STD 883C, Test Method 1019.4, but permits greater latitude in part selection for low-dose space systems. Cobalt-60 irradiation at 50-300 rad(Si)/s followed by 25-degrees-C anneal is shown to provide an effective test of oxide-charge related failures at low dose rates that is considerably less conservative than Method 1019.4 For MOS devices with gate oxides thinner than 100 nm, we show that an elevated temperature "rebound test" generally is not required for systems with total dose requirements less than 5 krad(Si). For thicker gate oxides and/or higher-dose system requirements, rebound testing per Method 1019.4 generally is required to ensure that devices do not fail in space due to interface-trap effects.