Split-gate flash memory and preparation method thereof

Abstract

The invention provides a split-gate flash memory and a preparation method thereof. The preparation method of the split-gate flash memory comprises providing a semiconductor substrate, wherein the semiconductor substrate comprises a storage area and a logic area adjacent to each other, a word line grid and a protection layer are formed at the storage area, and a polycrystalline silicon layer is formed on the semiconductor substrate; forming a patterned mask layer on the polycrystalline silicon layer, wherein the patterned mask layer is provided with an opening at the storage area; taking the patterned mask layer as the mask, and performing isotropy etching on the polycrystalline layer at the opening; etching the polycrystalline layer at the logic area; and etching the protection layer so asto form the split-gate flash memory. Only the polycrystalline layer is formed on the semiconductor substrate, and the isotropy etching is performed on the polycrystalline layer of the storage area sothat the polycrystalline residue cannot form at the location, close to the logic area, in the storage area. The yield of the split-gate flash memory can be improved, the production efficiency is improved, and the area utilization efficiency of the storage area is improved.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a split-gate flash memory and a preparation method thereof. Background technique [0002] In the current semiconductor industry, storage devices account for a considerable proportion of integrated circuit products, and the development of flash memory in memory is particularly rapid. Its main feature is that it can keep the stored information for a long time without power on. It has many advantages such as high integration, fast access speed and easy erasure, so it has been widely used in many fields such as microcomputer and automatic control. a wide range of applications. [0003] Flash memory is classified into two types: stack gate flash memory and split gate flash memory. The stacked gate flash memory has a floating gate and a control gate, wherein the control gate is located above the floating gate. The method of manufacturing the stacked gate flash memory is sim...

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Problems solved by technology

[0004] A split-gate flash memory includes a semiconductor substrate having a storage area and a logic area. When forming a gate of a logic transistor on the logic area of ​​the semiconductor substrate, it is easy to place a gate in the storage area close to the logic area (that is, the Polysilicon residues appear at the boundary of the above-mentioned storage area), and the residue often peels off in the subsequent process of preparing the split-gate flash memory, which causes poor electrical function and / or poor storage function of the split-gate flash memory , thus affecting the yield of split-gate flash memory

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