| 摘要 |
PURPOSE:To obtain a nonvolatile memory device having a tunnel SiO2 film of high quality by oxidizing a boundary between an Si substrate and a Ta2O5 film in oxidative atmosphere to form an SiO2 thin film. CONSTITUTION:After a Ta2O5 film 6 formed on an Si substrate 1, the surface of the substrate 1 is oxidized through the film 6 in O2 of 800-1,000 deg.C to form a tunnel SiO2 film 2' of approx. 20Angstrom thick. A gate electrode 4 of polysilicon or metal or metal silicide is provided as a mask, the films 6, 2' are reactively etched by sputtering with C3F8 gas, ion implanted to form source and drain 5, and a nonvolatile semiconductor memory is completed thereafter by a normal method. According to this configuration, writing and erasing voltages can be considerably reduced, the dielectric constant of the gate insulating film becomes high, mutual conductance increased, and the reading velocity is accelerated. SiO2 film 2' of high quality can be obtained. |
