Method for increasing sidewall width of floating gate flash memory and structure of floating gate flash memory

Abstract

The present invention provides a method for increasing the sidewall width of a floating gate flash memory and a floating gate flash memory structure. Using the method for increasing the sidewall width of the floating gate flash memory provided by the present invention, the sidewall of the second gate structure in the peripheral circuit area is formed with the ONO sidewall, the third oxide layer and the widened nitride layer stacked in sequence. Wide sidewall, since the width of the widened sidewall is increased compared with the ONO sidewall, the distance between the ion implantation region and the second gate structure for source-drain implantation in the peripheral circuit region is increased, which can reduce the leakage current of the high-voltage transistor, and, The area of ​​the drain extension region (LDD region) formed in the substrate around the second gate structure can be increased, so that the breakdown voltage of the high voltage transistor can be improved. In the floating gate type flash memory structure provided by the present invention, the second gate structure disposed in the peripheral circuit region has widened sidewall spacers including ONO spacers, a third oxide layer and a widened nitride layer.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for increasing the width of a side wall of a floating gate flash memory and a floating gate flash memory structure. Background technique [0002] Memories can be broadly classified into two categories: volatile (volatile) memories and non-volatile (non-volatile) memories. Volatile memory loses its stored information immediately when the system is turned off: it requires a constant power supply to maintain data. Most random access memory (RAM) falls into this category. Non-volatile memory can still maintain data information when the system is turned off or there is no power supply, and floating gate flash memory is a kind of non-volatile memory. [0003] At present, when making floating gate flash memory, in addition to forming multiple memory cells (cells) in the storage area, a peripheral circuit (periphery circuit) area is usually set around the storage area. ...

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Problems solved by technology

[0006] At present, the width of the ONO sidewall is usually increased by increasing the thickness of the silicon nitride of the ONO layer or the outermost layer of silicon dioxide. However, limited by the design rule of the minimum spacing between polysilicon gates, this method The spacing between memory cells is reduced, and it is easy to cause the morphology of the interconnection after the ONO sidewall is etched, blocking the subsequent source-drain implantation in the peripheral circuit area

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