A nor-type flash memory unit with raised common source area and preparation method thereof

Abstract

The invention discloses a NOR type flash memory unit that raises a common source region and a preparation method thereof. The flash memory unit includes: a substrate; a common source region and a drain region formed by implantation under the surface of the substrate; A channel region formed on the substrate surface between the drain regions; a tunneling layer formed over the channel region; a storage layer formed over the tunneling layer; a barrier layer formed over the storage layer; and The gate electrode above the barrier layer; in the process of forming the common source region, an epitaxial process is first used to lift the common source region, and then shallow trench isolation is formed by ion implantation below the shallow trench isolation region and the common source region of the flash memory cell. The lower part of the area is connected to the shared source area with low impedance. By introducing the epitaxial process, the present invention realizes the lifting of the common source area and at the same time completes the expansion of the active area of ​​the shallow trench isolation area along the trench width direction, effectively simulates the punch-through effect during the size reduction process of the traditional NOR type flash memory device, and realizes NOR The device is further scaled down along the trench length direction.

Description

technical field [0001] The invention belongs to the technical field of microelectronic devices and memories, and in particular relates to a NOR type flash memory unit with a raised common source region and a preparation method thereof. Background technique [0002] Semiconductor storage technology is one of the key technologies in the field of microelectronics technology. As information technology shifts from network and computing to storage as the core, the research on storage technology has become an important direction of information technology research. As an important product type, flash memory has developed rapidly in recent years due to the expansion of markets such as multimedia and smart phones. Flash memory mainly includes NOR flash memory and NAND flash memory. NOR flash memory is usually used for code storage because of its high-speed characteristics, and it is more common in mobile phones and communication chips. [0003] Conventional NOR-type flash memory chi...

AI Technical Summary

Problems solved by technology

On the other hand, in order to use the implantation method to realize the connection of the common source region, it is usually necessary to first remove the insulating layer in the STI. During the etching process, the silicon substrate in the source region is over-etched, and this silicon over-etch further makes Source Junction Depth Increased

With the shortening of the cell trench length, the direct consequence of this asymmetric structure will form a serious punch-through phenomenon, which makes it difficult for the memory cell to work normally.

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