Method for forming shallow trench isolation structure

Abstract

The invention relates to a method for forming a shallow trench isolation structure, comprising the following steps: providing a semiconductor substrate, successively forming a gate dielectric layer, a floating gate polycrystalline silicon layer, an interlaminated insulation layer and a control gate polycrystalline silicon layer on the semiconductor substrate; photo-etching and etching the control gate polycrystalline silicon layer, the interlaminated insulation layer and the floating gate polycrystalline silicon layer so as to form a control gate and a floating gate; dehydrating the semiconductor substrate, forming a photosensitive resist on the semiconductor substrate; and patterning the photosensitive resist, and etching the semiconductor substrate so as to form a trench, filling the trench. The semiconductor substrate is dehydrated with nitrous oxide, so as to prevent the generation of the cavity formed in the photosensitive resist caused by the water vapor which is volatilized and absorbed by silanol in the process of forming the photosensitive resist and avoid forming the area which is unnecessary to be etched under the etched photosensitive resist.

Description

technical field [0001] The invention relates to the field of semiconductor technology, in particular to a method for forming a shallow trench isolation structure. 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, the advancement of process technology and market demand have spawned 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., among which , 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] The standard physical structure of flash memo...

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Problems solved by technology

[0012] The problem solved by the present invention is that in the formation method of the shallow trench isolation structure, the residual silanol in the previous process cannot be removed before the photoresist is applied, thus causing voids inside the photoresist during the formation of the photoresist , resulting in multiple gaps between each memory cell in the shallow trench isolation structure formed after etching, which severely damages the storage performance of the flash memory

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