The impact of VLSI on integrated circuit radiation hardness

The important constituents of energetic radiation and the effects of the radiation on semiconductor devices and integrated circuits are briefly summarized. The basic silicon material and device parameters which are sensitive to energetic radiation and can be controlled by the IC designer are delineated. The trends of the variation of hardness with the level of integration for commercial MOS and bipolar integrated circuits are examined. It is shown theoretically how the hardness will vary as a function of device size for total ionizing dose, ionizing dose rate, and single particle (cosmic ray) environments. Contrary to what the trends had been indicating, it is shown that the basic component devices theoretically and actually become more radiation resistant as the devices are scaled down in size for implementing higher levels of integration. However, the parasitic MOS and bipolar devices created in implementing VLSI designs may cause the overall hardness to decrease. The reasons for the radiation hardness of the GaAs integrated circuits are discussed and put into perspective with the silicon technology.