Method for manufacturing flash memory control grid

Abstract

The invention discloses a method for manufacturing a flash memory control grid, which comprises the following steps of: dividing a semiconductor substrate into a core device area and a peripheral circuit area, and forming shallow trench isolation between the core device area and the peripheral circuit area on the semiconductor substrate; forming a tunnelling oxide layer on the surface of the semiconductor substrate; depositing and etching a first polysilicon layer, forming a floating grid and a selection grid in the core device area, and forming a peripheral circuit area control grid in the peripheral circuit area of the core device area; forming silicon oxide / silicon nitride / silicon oxide (ONO) layers on the surfaces of the first polysilicon layer and the tunnelling oxide layer; depositing a second polysilicon layer on the ONO layer; etching the second polysilicon layer above the peripheral circuit area to reach the surface of the ONO layer; and etching the rest second polysilicon layer above the peripheral circuit area again completely. Therefore, the height of the first polysilicon layer is retained to prevent ions from passing through the first polysilicon layer when subsequent ion implantation is performed, and thus, the physical properties of devices are retained.

Description

technical field [0001] The invention relates to a semiconductor manufacturing method, in particular to a manufacturing method of a flash memory control grid. Background technique [0002] Memory is used to store a large amount of digital information. According to recent surveys, memory chips account for about 30% of semiconductor transactions worldwide. Over the years, technological progress and market demand have led to more and more high-density various Types of memory, 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. , flash memory or FLASH has become the mainstream of non-volatile semiconductor storage technology, and is widely used in various electronic products such as smart cards, SIM cards, microcontrollers, and mobile phones. [0003] For the manufacturing process of 0.18um embedded flash memory, before manufactu...

AI Technical Summary

Problems solved by technology

For normal polysilicon etching, the usual method is one-step etching. In order to prevent the polysilicon formed in the gap from being completely removed, the degree of etching must be increased, resulting in excessive etching of the dielectric layer on the control gate of the peripheral circuit area. The performance of the device in the peripheral circuit area is reduced, and the production yield is reduced.

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