Real-time and on-site γ-ray radiation response testing system for semiconductor devices and its applications

The construction of a turnkey real-time and on-site radiation response testing system for semiconductor devices is reported. Components of an on-site radiation response probe station, which contains a 1.11 GBq Cs137 gamma (γ)-ray source, and equipment of a real-time measurement system are described in detail for the construction of the whole system. The real-time measurement system includes a conventional capacitance-voltage (C-V) and stress module, a pulse C-V and stress module, a conventional current-voltage (I-V) and stress module, a pulse I-V and stress module, a DC on-the-fly (OTF) module and a pulse OTF module. Electrical characteristics of MOS capacitors or MOSFET devices are measured by each module integrated in the probe station under continuous γ-ray exposure and the measurement results are presented. The dose rates of different gate dielectrics are calculated by a novel calculation model based on the Cs137 γ-ray source placed in the probe station. For the sake of operators' safety, an equivalent dose rate of 70 nSv/h at a given operation distance is indicated by a dose attenuation model in the experimental environment. HfO2 thin films formed by atomic layer deposition are employed to investigate the radiation response of the high-κ material by using the conventional C-V and pulse C-V modules. The irradiation exposure of the sample is carried out with a dose rate of 0.175 rad/s and ±1 V bias in the radiation response testing system. Analysis of flat-band voltage shifts (ΔVFB) of the MOS capacitors suggests that the on-site and real-time/pulse measurements detect more serious degradation of the HfO2 thin films compared with the off-site irradiation and conventional measurement techniques.