Process integration method for improving multi-step polysilicon etching damage in split-gate flash memory

Abstract

The invention discloses a process integration method for improving multi-step polysilicon etching damage of split-gate flash memory, comprising: step S1: providing a silicon-based substrate, and forming a split-gate flash memory device thereon; step S2: in the device preparation process, Forming a silicon nitride layer, and exposing the active area where local silicon oxidation needs to be formed in the subsequent process; step S3: performing dry etching on the silicon nitride layer to form a silicon nitride sidewall structure, and setting the active area Etching the groove; step S4: performing a silicon oxidation process on the exposed area of ​​the active region to form a silicon dioxide barrier layer; step S5: removing the silicon nitride sidewall structure, and performing subsequent polysilicon growth and etching processes. The invention can effectively avoid the etching damage of the active area caused by the multi-step polysilicon etching in the divided-gate structure flash memory, improve the stability of the overall process, and the process is simple and conveniently embedded into the existing process flow, and greatly reduces the The risk of etching damage in the active area also meets the technical requirements of FAB and is worthy of popularization and application.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a process integration method for improving multi-step polysilicon etching damage of flash memory with divided gate structure. Background technique [0002] Due to its advantages of high density, low price, and electrical programmability and erasability, flash memory has been widely used as the best choice for non-volatile memory applications. At present, the floating-gate non-volatile flash memory is mainly divided into two types according to its structure: ETOX flash memory and split-gate flash memory. The main difference between the two lies in the programming / erasing method and cell structure. The programming / erasing method of ETOX flash memory is: channel hot electron injection / FN tunneling method, and the split-gate flash memory is: source channel hot electron Injection / field-enhanced poly-to-poly FN tunneling method; structurally, ETOX flash memory is a...

AI Technical Summary

Problems solved by technology

[0007] The present invention is aimed at the existing multi-step multi-step polysilicon total dry etching and wet cleaning amount is too much, if the active area with high risk of etching damage is not processed, the original surface of the active area The silicon dioxide film will be easily etched through, causing etching damage in the active area, wafer scrapping, causing huge economic losses and other defects Provide a process integration method for improving the multi-step polysilicon etching damage of split-gate flash memory

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