Flash memory cell and method of forming same

Abstract

A flash memory unit and its formation method. The formation method of the flash memory unit includes: providing a semiconductor substrate, a first dielectric layer and a floating gate material layer on its surface are formed on the surface of the semiconductor substrate; forming a layer covering the first dielectric layer and the floating gate material layer; a second dielectric layer on the surface of the gate material layer and a control gate material layer on the surface; forming a hard mask layer with an opening on the surface of the control gate material layer; forming a first spacer in the opening; using the first spacer and the hard mask The film layer is used as a mask, and the control gate material layer is etched to form a first groove; in the first groove, a second side wall located on the side wall of the control gate material layer is formed; and the second side wall is etched along the first groove. The dielectric layer, the floating gate material layer and the first dielectric layer form a second groove and a floating gate; a tunnel oxide layer is formed on the inner wall surface of the second groove; and a tunnel oxide layer is formed on the surface of the tunnel oxide layer that fills the first groove and the floating gate. Two-groove word lines. The above method can improve the coupling efficiency of the control gate to the floating gate in the flash memory, thereby improving the erasing and writing performance of the flash memory.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a flash memory unit and a forming method thereof. Background technique [0002] In the current semiconductor industry, integrated circuit products can be mainly divided into three types: logic, memory and analog circuits, among which storage devices account for a considerable proportion of integrated circuit products, such as RAM (random access memory), DRAM (dynamic Random access memory), ROM (read-only memory), EPROM (erasable programmable read-only memory), FLASH (flash memory) and FRAM (ferroelectric memory), etc. [0003] In memory, the development of flash 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 ap...

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Problems solved by technology

[0006] The coupling efficiency of the control gate to the floating gate of the existing flash memory is low, and the erasing and writing efficiency of the flash memory is low, which needs to be further improved

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