A method for preventing floating gate and word line polysilicon residue of split-gate flash memory

Abstract

The present invention provides a method for preventing floating gates and word line polysilicon residues of split-gate flash memory, wherein the process of oxidizing polysilicon is changed from performing after logic gate etching to performing after flash memory unit word line etching, Including: first step: forming a logic gate polysilicon layer, and performing logic gate polysilicon etching; second step: forming a flash memory unit word line polysilicon layer, and performing word line polysilicon etching; third step: etching The etched logic gate polysilicon layer and flash cell word line polysilicon layer perform polysilicon oxidation treatment. In the method for preventing the floating gate and word line polysilicon residue of split-gate flash memory according to the present invention, by changing the process steps of polysilicon oxidation, not only the short channel effect of the logic device in the flash memory unit can be solved, but also the flash memory unit can be eliminated The floating gate and word line polysilicon are left after etching to avoid the failure of the flash memory function.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, and more specifically, the invention relates to a method for preventing polysilicon residues in floating gates and word lines of split-gate flash memories. Background technique [0002] Flash memory has become a research hotspot in non-volatile memory due to its convenience, high storage density, and good reliability. Since the first flash memory product came out in the 1980s, with the development of technology and the storage needs of various electronic products, flash memory has been widely used in mobile and communication devices such as mobile phones, notebooks, handheld computers and U disks. . [0003] Flash memory is a non-volatile memory. Its operating principle is to control the switch of the gate channel by changing the critical voltage of the transistor or memory cell to achieve the purpose of storing data, so that the data stored in the memory will not disappear due to powe...

AI Technical Summary

Problems solved by technology

[0007] In the early stages of flash memory products, some polysilicon residues have been found to cause low yield issues due to process excursions

If the word line and bit line are bridged, the product will show a full row failure after a chip erase operation, and there will be a column programming failure

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