Radiation-Induced Charge Trapping in Thin. A1[sub2]O[sub3]/SiO[subx]N[suby]/Si( 100) Gate Dielectric Stacks.

We examine the total-dose radiation response of capacitors and transistors with stacked Al&sub2;O&sub3; On oxynitride gate dielectrics with Al and poly-Si gates after irradiation with 10 keV X-rays. The midgap voltage shift increase monotonically with dose and depends strongly on both Al&sub2;O&sub3; and SiOxNy thickness! The thinnest dielectrics, of most interest to industry, are extrenely hard to ionizing irradiation, exhibiting only ∼50 mV of shift at a total dose of 10 Mrad(SiO&sub2;) for the worst case bias condition. Oxygen anneals are found to improve the total dose radiation response by ∼SO% and induce a small amount of capacitance-voltage hysteresis. Al&sub2; O&sub3; /SiOxNy dielectrics which receive a ∼1000°C dopaut activation anneal trap ∼12% more of the initial charge than films annealed at 550°C. Charge pumping measurements show that the interface trap density decreases with dose up to 500 krad(SiO&sub2;). This surprising result is discussed with respect to hydrogen effects in alternative dielectric materials, and may be the result of radiation-induced hydrogen passivation of some of the near-interfacial defects in these gate dielectrics. [ABSTRACT FROM AUTHOR]