Manufacturing method of flash memory unit of shared source line and flash memory unit of shared source line

Abstract

The invention provides a manufacturing method of a flash memory unit of a shared a source line, which comprises the steps of providing a substrate, wherein the substrate comprises a storage region anda logic region, and a gate oxide layer, a floating gate layer and a first dielectric layer are formed on the substrate; forming a first side wall structure; forming a second groove; forming an ONO side wall structure; forming a shared source line; executing a back etching process to remove the undoped source line material layer residues in the logic region; and forming a source line oxide layer on the shared source line. The formed ONO side wall structure can effectively inhibit oxygen atoms from entering an interface between the gate oxide layer and the floating gate layer from the shared source line in the subsequent process of forming the source line oxide layer, so that the floating gate layer is prevented from being oxidized, the smiling effect is avoided, the coupling capacitance between the shared source line and the floating gate layer is increased, and the programming efficiency of the device is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for manufacturing a flash memory unit sharing a source line and the flash memory unit sharing a source line. Background technique [0002] In the manufacturing process of the split-gate flash memory unit sharing the source line, a gate oxide layer and a floating gate layer are usually formed on the substrate first, and the floating gate layer is etched to form a trench in the floating gate layer, and then The trench is directly filled with polysilicon doped with N-type ions (such as phosphorus ions) as the shared source line of the flash memory unit. After the shared source line is formed, it is usually necessary to perform a chemical mechanical polishing process on the shared source line to planarizing the surface of the shared source line, but after performing chemical mechanical polishing on the shared source line, the source line polysilicon remai...

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to provide a kind of manufacturing method of the flash memory cell of shared source line and the flash memory cell of shared source line, to solve the problem that the source line polysilicon remains on the surface of the first dielectric layer of the logic area of ​​the flash memory cell and produce smile effect

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