Electron trapping in SiO2 due to electron‐beam deposition of aluminum

Electron trapping in the SiO2 layer of n‐channel polycrystalline silicon‐SiO2‐silicon field‐effect transistors with electron‐beam‐evaporated aluminum was studied. The increased electron trapping was attributed to the x rays generated when the electron beam impinged on the aluminum target. Traps with low‐field capture cross sections greater than 10−13 cm2 are associated with the x‐ray‐induced positively charged centers, while traps with low‐field capture cross sections of about 1×10−15 cm2 are associated with the x‐ray‐induced neutral centers. For the silicon‐gate devices, both traps could be effectively reduced by annealing in dry forming gas at 550 °C for 20 min. As reported earlier, the capture cross section of the positively charged traps has a strong field dependence of approximately E−3ox and is approximately independent of temperature. The field dependence of the capture cross section of the neutral traps is much weaker, with roughly a σ  =σ0 exp(−bEox) dependence, where σ0=1.6×10−15 cm2 and b=7.35×...