| 摘要 |
In this invention a micro vacuum tube is used to form a flash memory cell. The micro vacuum tube is position over a floating gate and is used to program, erase, read and deselect the flash memory cell. A first embodiment includes a source and drain with the floating gate to provide a means to produce bit line current to be read by the flash memory sense amplifiers. In a second embodiment the source and drain are eliminated and cathode gate current is used to indicate the state of the flash memory cell. In a third embodiment the floating gate is replace with a diffusion in the semiconductor substrate. The cathode tip is formed by filling a depression in a sacrificial material used to temporarily fill the volume that will be the vacuum chamber when the vacuum tube is completed. The tip can be a convex cusp producing a needle like point or an elongated convex cusp having an sharp line edge. The two different shaped cathode tips depend on the shape of the vacuum chamber, and the elongated convex cusp produces a more efficient emission of electron.
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