Effect of different total ionizing dose sources on charge loss from programmed floating gate cells

Abstract

We irradiated programmed Floating Gate (FG) memory arrays with different radiation sources, including 10 keV X-rays, /sup 60/Co /spl gamma/-rays, and 27 MeV protons. After irradiation, FGs experience a net charge loss which can degrade the stored information in terms of MOSFET threshold voltage. The charge loss is the result of two different phenomena: charge generation/recombination in the oxides and photoemission from the FG. The threshold voltage shift in irradiated devices depends on the radiation source: strong dose enhancement phenomena were found after X-ray irradiation, whereas proton results closely follow /spl gamma/-ray results.