Study Of Proton Radiation Effects On Nanometer CMOS Integrated Circuits

The rapidly developing aerospace technology requires integrated circuits(ICs)with high performance while maintains high reliability.Although nano CMOS ICs have improvements in performance,they also bring critical challenges in reliability.As one of the most abundant particles in space environment,protons seriously threaten the normal operation of nano CMOS ICs in aerospace applications due to their strong penetration ability.In this thesis,65 nm and 28 nm CMOS ICs are used as research objects.Theoreti-cal analyses,software simulations and proton irradiation experiments are taken as re-search methods to study proton radiation-induced low-energy recoil charge deposition mechanisms,SET,SEU and mechanisms of cumulative proton radiation affecting tran-sient effects.The main work and innovations are as follows.(1)The recoil ionization efficiency is taken into consideration in SEE simulation and analysis,which makes SEE analysis more consistent with the real physical processes.TRIM Monte Carlo simulation method is used to extract the recoil ionization efficiency(<100%).Furthermore,the ionization efficiency was introduced in the calculation of recoil charge deposition,which provides theoretical support for proton-induced SER evaluation.The simulation found that the ionization energy of the low-Z recoil is gener-ally larger.For example,the ionization energy of C recoil(Z=6)in SiC is greater than that of Si,the ionization energy of O recoil(Z=8)in SiO2 is greater than that of Si.These analyses provide several insights for radiation-harden by process.(2)SETs induced by low-energy(<10 MeV)protons were discovered through experi-ments.Moreover,the related mechanisms are studied.Our experiment found that pulse widths of low-energy(?10 MeV)proton-induced SETs can exceed 200 ps in 65 nm CMOS bulk technology.With proton energy increases,the average SET pulse width al-so increases.As space is a proton-rich environment,the SER induced by low-energy proton-induced SETs cannot be ignored.Analyses suggest that SETs induced by low-energy proton direct ionization cannot be captured by the on-chip self-trigger SET capture circuit.The captured SETs are mainly induced by oxygen and silicon recoils.The pulse width of SETs induced by oxygen recoils tends to be wider,which can be ex-plained by two reasons.(3)Low-energy(?10 MeV)proton-induced MCU patterns in 65 nm bulk CMOS SRAM were discovered by proton radiation experiment.Moreover,the influence of SRAM critical charge on proton SEU and the mechanisms of recoil-induced SEU are studied by simulations.Low-energy proton-induced MCUs usually appear along the SRAM bit line,these upset cells don't belong to a word.Therefore,these MCUs can be corrected by ECC.Analysis suggest that these MCUs are mainly induced by charge dif-fusion and recoil-induced well-potential modulation.With the help of TCAD and Geant4 simulations,this work explained the different trends of the SEU cross section with increasing proton energy(?10 MeV)(i.e.,1.gradually decreasing,2.decreasing first,then increasing,3.gradually increasing).The simulations also demonstrated that oxygen-induced SEUs were found to be the most among the recoil-induced SEUs.(4)The influence of cumulative high-fluence proton radiation on transient effects was demonstrated and the relevant mechanisms were studied.The alternate heavy ion/proton/heavy ion radiation experiment found that cumulative proton radiation can significantly increase heavy ion SET pulse width and cross-section.Within a fluence of 3×1013/cm2 1.2 MeV proton,the main mechanism for this phenomenon is that pro-ton-induced TID effects can reduce PMOS drive current Ion.For a fluence above 1014/cm2 1.2 MeV proton,proton radiation also increases N-well resistivity and de-creases carrier mobility,thereby increasing the chip SET sensitivity.For applications those will be irradiated by high-fluence protons,it is recommended that the alternate heavy ion/proton/heavy ion experiments should be performed for radiation hardness as-surance(RHA).At last,the unfinished work and future research directions of proton radiation ef-fects on nano CMOS ICs are discussed.In summary,this thesis involves the phenomena,mechanisms and related models of nano CMOS ICs under proton radiation.It can pro-vide some references for the selection of aerospace radiation-harden nano CMOS tech-nologies,the radiation-harden CMOS circuit design,the SER evaluation and RHAs.