Correlation of proton and heavy-ion test results on CMOS bulk memories used for space applications

Experiments were performed to determine the heavy-ion and proton sensitivity of CMOS bulk 2 K×8 RH space-qualified SRAMs (static random access memories). The experimental data obtained on both the HC6116 and HC6216 devices indicate that the more immune a device is to upsets from heavy ions, the more immune it will be to upsets from protons. The tests were conducted at room temperature and worst-case supply voltage on devices with several different cross-coupled memory cell resistor values. The results indicated correlation between heavy-ion LET (linear energy transfer) threshold versus proton apparent threshold. The heavy-ion data indicate a correlation between the upset cross-sections and resistor values as well. Several proton energies were used to determine energy dependence of proton sensitivity. A special assessment/evaluation of the measured. calculated, and inferred parameter values was performed. The results were used to predict upset rates for a mission-specific space environment. With the given mission environment in mind (28.5° inclination circular orbit at 550-km altitude), the HC6216 device with a minimum of a 370-kΩ memory cell resistor was chosen as the device to use