Method of forming a discrete gate memory device

Abstract

The present invention provides a method for forming a discrete gate storage device, comprising: providing a semiconductor substrate, and sequentially forming a gate dielectric layer, a first polysilicon layer, an interlayer insulating layer and a second polysilicon layer on the semiconductor substrate layer; etch the second polysilicon layer and the interlayer insulating layer until the first polysilicon layer is exposed to form a control gate; form sidewalls on the sidewalls of the control gate and the etched interlayer insulating layer ; Using the control gate and the sidewall as a mask, using an isotropic plasma etching process to etch the first polysilicon layer, so that the outside of the etched first polysilicon layer has a sharp point. Compared with the prior art, the process of the invention is simple and low in cost, and because the precision of the plasma etching process is easy to control, it is more suitable for the manufacture of devices with small feature sizes.

Description

technical field [0001] The invention relates to a semiconductor manufacturing process, in particular to a method for forming a discrete gate storage device. Background technique [0002] In the current semiconductor industry, integrated circuits can be divided into three main types: analog integrated circuits, digital integrated circuits and digital / analog hybrid integrated circuits. [0003] As an important type of digital integrated circuits, storage devices, especially flash memory (flash memory, referred to as flash memory) are developing rapidly, mainly because flash memory can store information for a long time without power on, and has a high degree of integration. , fast access speed, easy to erase and rewrite, etc. [0004] The standard physical structure of flash memory is called a memory cell (bit). The structure of the memory cell is different from that of conventional MOS transistors. The gate (gate) of a conventional MOS transistor and the conductive channel ...

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Problems solved by technology

[0012] The above-mentioned method of forming a floating gate with a sharp edge adopts the process of partial thermal oxidation and then wet etching. Due to the limitation of the precision of the local thermal oxidation and wet etching process, it is only applicable to flash memory with larger feature size. For feature size For the flash memory structure below 130nm, the process precision cannot meet the corresponding requirements

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