It has become increasingly difficult to simulate their responses to radiation as the ICs become smaller and hence more complex. a multi-scale, hierarchical
simulation approach is required here as the time scales and sizes extend over orders of magnitude. this article describes the use of multi-scale simulations examining enhanced low-dose-rate sensitivity (ELDRS) in bipolar
transistors and single-event effects (SEE) in CMOS ICs. The simulation tools operating at one level of abstraction pass he information to another tool operating at another level of abstraction.
The integrated-circuit technologies have changed dramatically these years owing to the developments in the microelectronic materials and device structures.This has affected the radiation hardness is affected dramatically and in many unexpected ways. The materisl used in the IC determine the effects of carrier generation, carrier transport, charge trapping, and defect formation. device-edge and inter-device leakage currents and other efffects arising from the radiation-induced trapped charge largely depends on the device geometries and doping profiles. multiple-bit upsets and complicated angular effects may arise due to the change in the device scaling. This article describes the analyzing radiation effects in advanced technologies, emphasizing multi-scale simulations that are based on detailed physical modeling of radiation interactions and carrier transport.

The radiation present may be classified into long-term and transient.
Long-Term Effects
The defects leading to longterm changes in device characteristics maybe produced by radiation. deeply trapped charge or interface traps appeazar in the oxide layer. both insulator and semiconductor regions have diaplaced charges due to Non-ionizing energy loss.

Transient Effects
reductions in gate oxide thicknesses and increases in doping densities has improved the total-dose hardness of commercial ICs. The advanced technologies in avionics and the electronics operated in the space have to worry about the Single-event effects which is a serious problem.
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