Method of forming semiconductor device

Abstract

A method for forming a semiconductor device, including: providing a semiconductor substrate, including a storage area and a logic area; forming a plurality of first polysilicon layers on the storage area; forming a control gate dielectric material layer covering the first polysilicon layer; Form a second polysilicon layer covering the control gate dielectric material layer and the logic area; etch parts of the second polysilicon layer and the control gate dielectric material layer to form a second opening that exposes the top surface of the first polysilicon layer ; Forming a third polysilicon layer covering the second polysilicon layer; etching part of the third polysilicon layer, the second polysilicon layer, the control gate dielectric material layer and the first polysilicon layer in the storage area, Forming the select gate, floating gate and control gate located on the floating gate of the flash memory device; forming a protective layer covering the select gate and control gate; forming a photoresist layer on the protective layer; etching the third polysilicon layer in the logic area and a second polysilicon layer that forms the gate of the logic transistor. Prevent the occurrence of depressions on the control gate and select gate.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming a semiconductor device. 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 memory devices account for a considerable proportion of integrated circuit products. Among memory devices, flash memory devices (flash memory) have developed particularly rapidly in recent years. Its main feature is that it can keep stored information for a long time without power on, and has many advantages such as high integration, fast access speed, easy erasure and rewriting, etc. The field has been widely used. [0003] A schematic structural view of an existing flash memory device, including: a semiconductor substrate, a separate storage transistor gate stack and a selection transistor gate stack located on the semiconductor substrate, a...

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Problems solved by technology

[0004] In the prior art, when making a flash memory device, it is usually necessary to integrate logic transistors in other regions of the semiconductor substrate. The gate of the logic transistor uses the same layer of polysilicon as the control gate and selection gate of the flash memory device, and the flash memory device and the logic transistor are integrated. In the integrated manufacturing process, the flash memory device is generally fabricated first, and then the logic transistor is fabricated. When forming the gate of the logic transistor, it is easy to over-etch the surface of the control gate and selection gate of the flash memory device that has been formed. recessed defect

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