Study On Total Ionizing Dose Effect And Radiation Hardening Of MOSFET In 65nm Technology

With the application of integrated circuits in aerospace, the total ionizing dose(TID) radiation effects of semiconductor devices and circuits are paid more and more attention to. Some new properties of the TID effects of the device has been discovered. With device dimensions into nanometer domain, the TID effect of MOSFET in 65 nm technology is studied in this paper. Firstly, the excellent TID performance of high ? gate dielectric is demonstrated. Secondly, the influence of radiation induced trapping charge in the STI oxide on MOSFET characteristic and radiation hardening of MOSFET are simulated with ISE.The transfer characteristic curves of n MOSFET under different irradiation doses are obtained by simulation. The leakage current increases and The subthreshold characteristics becomes worse with the add of irradiation dose. The potential of the substrate near STI sidewall is increased by the radiation induced trap charge, for which the valence band and conduction band is bended down. The surface of substrate near STI sidewall is operated in weak inversion at low radiation dose and the depth of substrate near the STI sidewall is operated in inversion at high radiation dose. The variation of the characteristic parameters of transistor such as threshold voltage, mobility, and transconductance are summarized. According to the relationship between the threshold voltage and the radiation dose, the modeling method of the effect of different irradiation dose on the threshold voltage of the device and a new apporach to estimate the carrier mobility change with increasing irradiation dose are presented. Enhancement in DIBL, channel length modulation, and narrow width effect are observed. The DIBL and channel length modulation effect is enhanced by the oxide trapped charge in the STI sidewall which increases the electric field nearby and the surface potential of substrate along STI sidewall. Narrow channel effect enhancement is due to the electric field produced by the radiation induced trap charge in two STI sidewalls of narrow channel transistor.The TID effect of pMOSFET is also discussed. The necessity of n MOSFET radiation hardening is obtained from two aspects: the difference of TID effect of p MOSFET and n MOSFET and the static power consumption. A method for determining the super steep retrograde doping location based on the location of the space charge region when the semiconductor surface Fermi level coincides with intrinsic Fermi level and the maximum depth of the source drain region. Good anti-radiation properties of the transistor with the above doping profile is validated. The radiation characteristic of the transistor with threshold adjustment injection and the above super steep retrograde doping is studied and better anti-radiation performance is achieved. The TID effect of MOSFETs with H gate and annular gate are researched. The mechanism of radiation hardening implementing the H gate is based on the isolation of the main channel region from the STI sidewall by the symmetric part of H gate. Not only does the annular gate separates the channel from the STI region, but also makes STI region not be energized by the gate electrode.