| 摘要 |
PURPOSE:To read a memory cell at a low voltage by injecting the same conductivity type majority carrier as that of a substrate on a floating gate at the time of writing to make it nonconductive before writing and conductive after writing. CONSTITUTION:A source is set to zero V, and a first control gate 1 is set to a positive voltage at the time of writing to generate electron hole pairs near the drain of the gate 1. Since a lower layer uses polysilicon at the gate 1, a writing positive voltage may be low. A negative voltage is applied to a second control gate 3 at this time to implant the holes of majority carrier to a floating gate 2. Thus, since the holes are not implanted to a cell which is not written, it is nonconductive, the written cell is implanted with the holes to come in a conductive state. Accordingly, the substrate concentration of the cell is the same as that for reading/writing, its constitution is simple, and the cell can be read at a low voltage. |
