Flash memory device structure and manufacturing method thereof

Abstract

The invention relates to the technical field of semiconductor memory manufacturing, in particular to a flash memory device structure and a manufacturing method thereof. The flash memory device structure comprises a selection gate, a first split gate and a second split gate, wherein the selection gate is arranged between the first split gate and the second split gate; each of the first split gate and the second split gate comprises a floating gate structure and a control gate structure which are sequentially stacked from bottom to top; the floating gate structure comprises a floating gate dielectric layer and a floating gate polycrystalline silicon layer, the floating gate dielectric layer covers the flash memory cell region of the substrate layer, and the floating gate polycrystalline silicon layer covers the cell main body region of the floating gate dielectric layer; a first step structure which takes the upper surface of the floating gate polycrystalline silicon layer as an upper step surface, takes the upper surface of the isolation structure as a lower step surface and takes the side surface of the floating gate polycrystalline silicon layer as a step side surface is formed at the edge of the cell main body region; and the control gate structure comprises a polycrystalline silicon spacer layer and a control gate polycrystalline silicon layer, the polycrystalline silicon spacer layer covers the surface of the first step structure, and the control gate polycrystalline silicon layer covers the polycrystalline silicon dielectric layer.

Description

technical field [0001] The present application relates to the technical field of semiconductor memory fabrication, and in particular, to a structure of a flash memory device and a fabrication method thereof. Background technique [0002] Floating-gate split-gate flash memory is widely used in various embedded electronic products such as financial IC cards, automotive electronics and other fields because it is beneficial to save chip area and improve storage integration density. [0003] figure 1 A cross-sectional structural schematic diagram of the device structure of a 2-bit / cell (two bits per memory cell) split-gate floating-gate flash memory in the related art is shown. refer to figure 1 , the flash memory cell includes a substrate layer 11, a shallow trench isolation structure 16 is formed in the substrate layer between two adjacent flash memory cells, and a first split gate and a second split gate are formed on the substrate layer 11 of the flash memory cell The firs...

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Problems solved by technology

[0005] The present application provides a flash memory device structure and its manufacturing method, which can solve the problem in the related art that with the further shrinking of the flash memory device size, the coupling effect from the selection gate to the floating gate cannot be reduced by thinning the floating gate

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