Effects of high energy neutrons and resulting secondary charged particles on the operation of MOSFETs

Study for penetration of nuclear radiation into semiconductor materials had been of theoretical interest and of practical important in these recent years, driven by the scaling down of semiconductor materials. This paper reviews the typical effects occurring in the operation of MOSFETs due to irradiation with neutrons resulting from Deuterium-Tritium (D-T) reaction. Charge trapping features of MOSFETs were investigated by in situ irradiation and post irradiation methods. Analytical explanations and calculations on the numeric change that occurs in the MOSFETs were conducted using a series of simulations. The oxide insulating layer of MOSFET is found to be most sensitive to the neutron radiation. Energy deposition of neutrons in MOSFET occurs via two mechanisms; firstly by trapped charge buildup in the silicon dioxide (SiO₂) layer and secondly, an increase in the density of trapping states at the SiO₂ interface. The bombardment of neutron in the MOSFET model produces at least three secondary particles, which are alpha (α) particles, proton (p) particles and silicon recoil atoms, through the reactions of (n,α), (n,p) and neutron scattering respectively. Damage efficiencies of these secondary particles are discussed in direct comparisons.