Double-bit flash memory, and programming, erasing and reading method thereof

Abstract

The invention discloses a double-bit flash memory, which comprises a P-type substrate, a first floating gate, a second floating gate, a first control gate and a second control gate, wherein the P-type substrate comprises a source terminal and a drain terminal; the first floating gate, the second floating gate, the first control gate and the second control gate are sequentially located at the upper side and the lower side of the substrate; the first floating gate and the second floating gate are N-type doped polycrystalline silicon; the second control gate is made of P-type polycrystalline silicon; the second control gate is made of N-type polycrystalline silicon; in a programming process, positive drain terminal voltage is exerted on the drain terminal; the source terminal is grounded; the state of electrons stored in the corresponding floating gate is defined to be '1'; if the '1' state is programmed on any control gate, positive grid voltage is exerted on the corresponding control grid, so that an electronic inversion layer is generated on the groove of the substrate; under the accelerating action of the drain terminal voltage, groove electrons obtain enough energy and jump across a potential barrier between a grid oxidation layer and substrate silicon to become hot electrons; the hot electrons are injected into the floating gates to finish programming under the action of the grid voltage. According to the double-bit flash memory, the storage capacity per unit area of a floating gate flash memory is expanded, so that the dimension of the floating gate flash memory can be reduced.

Description

technical field [0001] The present invention relates to the technical field of semiconductors, more specifically, to a double-gate double-bit flash memory and programming, erasing and reading methods thereof. Background technique [0002] In semiconductor storage devices, flash memory (Flash Memory) is a long-life non-volatile (that is, it can still maintain stored data information in the case of power failure) memory. Flash memory is a variant of electronically erasable read-only memory (EEPROM). Because it can still save data when power is turned off, it can usually be used to save setting information, such as in the BIOS (basic program) of a computer, PDA (personal digital assistant) , Save data in digital cameras, etc. The characteristic of flash memory is that it can perform fast erasing operation in block (sector) unit. The writing operation of the flash memory must be carried out in the blank area. If the target area already has data, it must be erased before writin...

AI Technical Summary

Problems solved by technology

The single-gate floating gate flash memory structure causes each storage unit to only distinguish between two different states, that is, "0" and "1", so that each storage unit has only 2bit (bit, bit) storage capacity

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