A. Tokuhiro, M. Bertino, H. Dharavat, J. Munson, and J. Farmer
University of Missouri
M. Pecht, and D. Das
CALCE EPSC
University of Maryland
College Park, MD 20742
Abstract:
The tolerance level of selected commercial-off-the-shelf (COTS) CMOS devices to ionizing radiation was determined in a series of tests conducted at the University of Missouri ¨C Rolla Nuclear Reactor facility. Care was taken as practical to follow the military standard, MIL-STD-883E during the test phase. The following CMOS AND gates were evaluated: ST Microelectronics M74HC08 (oxide thickness = 550 Å ); Fairchild Semiconductor 74AC08 (250 Å ); Texas Instruments SN74AHC08 (185 Å ). The parameter most affected by ionizing radiation was the rise time. Rise time increased with increasing irradiation dose, especially in ICs with thick oxide layers. We estimate that the 550Å oxide ICs fail at frequencies higher than about 100 kHz after exposure to a dose of 10 MRad. Devices with thinner oxide layers remained operational at least at frequencies of 1 MHz even after irradiation with 16 MRad. Cost and time estimates of our testing procedure are discussed.
Key words: CMOS, Oxide Thickness, Radiation Resistance, Gamma Radiation
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