NORD flash memory and manufacturing method thereof

Abstract

The invention relates to the field of semiconductor integrated circuit manufacturing, in particular to an NORD flash memory and a manufacturing method thereof. The manufacturing method of the NORD flash memory at least comprises the following steps that a semiconductor device provided with a word line structure and a control gate structure is provided, the word line structure comprises word line polycrystalline silicon, and the control gate structure is located atthe two sides of the word line polycrystalline silicon; maskless etching is carried out on the upper surface of the semiconductor device, and etching is carried out to remove the upper layer of the word line polycrystalline silicon; the upper surface of the word line polycrystalline silicon is oxidized to form a protective oxide layer; a silicon nitride layer isdeposited and formed on the protective oxide layer; under the protection of the silicon nitride layer and the protective oxide layer, the control gate structure is etched to form NORD flash memory cells; and an isolation trench structure is manufactured and formedbetween the adjacent NORD flash memory cells. According to the NORD flash memory and the manufacturing method thereof, the problem that the uniformity of theprotective oxide layer is difficult to guarantee in related technologies can be solved.

Description

technical field [0001] The present application relates to the field of semiconductor integrated circuit manufacturing, in particular to a NORD flash memory and a manufacturing method thereof. Background technique [0002] In the process of producing NORD flash memory in the related technology, after depositing and grinding the word line polysilicon, the upper surface of the word line polysilicon is oxidized to form a protective oxide layer. Due to the different crystal directions, the oxidation rate of the word line polysilicon is different. , sharp corners that are not easily oxidized will be formed on the polished surface of the word line polysilicon, which will cause poor uniformity of the formed protective oxide layer. For example, the thickness of the protective oxide layer formed on the sharp corners that are not easily oxidized It can happen that sharp corners are not covered by the protective oxide layer. [0003] In addition, since the word line polysilicon usually...

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Problems solved by technology

[0004] This application provides a NORD flash memory and its manufacturing method, which can solve the problem that the uniformity of the protective oxide layer is difficult to guarantee in the related art

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