A 1/f Based Research Of MOSFET Radiation Effects And Nondestructive Estimate Method

MOS devices have to suffer from ionizing radiation as they are widely used in the environment of space, nuclear energy and nuclear weapon. The parameter defradation, half and /or full permanent damage even failure in function of MOS devices will occur due to the generation of radiation-induced oxide trapped charges and interface traps. In order to keep the devices work well in the environment of ionizing radiation, radiation-anneal techniques of ionizing radiation are generally used. The more important thing is that this method will induce some new latent defects in the device under test, let alone this method is expensive, time-waste and destructive. It is therefore useful to consider whether a simple, fast and nondestructive method can be defined to characterize the ability of MOS devices to restrain radiation.The method of characterizing ability of MOS devices to restrain radiation is thoroughly studied by analyzing the relationship between 1/f noise and radiation effects.1 The radiation experiments of MOSFETs, with different channel area and type, have been made using ⁶⁰Coγas radiation source. The results demonstrate that there are obvious relationships between 1/f noise of pre-radiation and the changes of threshold voltage and transconductance after radiation. The results also tell that the magnitude of 1/f noise becomes large with the dose of radiation adding, which predicates the more tapped charges induced by radiation and its distribution is also changed.2 Based on the two-step interface traps buildup model and the statistical thermodynamics mechanics of point defects in solids, a relation between the radiation induced increase of oxide hole-traps and the buildup of interface traps in MOSFET is proposed. Then, use the correlation between pre-irradiation 1/f noise power spectral density and post-irradiation oxide-trap charge, a sim-empirical expression between pre-irradiation 1/f noise and post-irradiation interface traps buildup is established. It is agree well with the experimental results. This model show that the process of interface traps buildup was influenced by the increasing of oxide hole-traps that could disassemble hydrogen into proton in irradiation. So, the magnitude of pre-irradiation 1/f noise direct ratio to post-irradiation interface-trap charge and sub-threshold slope.The work done above not only proving that the 1/f noise can play a important role in investigate MOSFET irradiation effects, but also providing a new nondestructive method to estimate MOSFET radiation response.