Method for forming 3D NAND flash memory

Abstract

The invention relates to the manufacturing technical field of a semiconductor, and particularly to a method for forming a 3D NAND flash memory. By optimization of structures of channel holes and gate lines, nine rows of perpendicular hole patterns can be placed in one gate line; then after the processing of the channel holes is finished, the separation of the channel holes in the upper and lower rows can be realized through etching of a first trench so as to reduce the required area of a second trench and overlap; finally, the separate line connection of each CH BL in the same layer of GL SL is realized through a back section dual-pattern etching process so as to effectively reduce the size of an effective storage cell; and therefore, under the premise of not increasing the technological difficulty, the equivalent storage area is improved by about 35-40% by optimization of the planar process structure and the back section line connecting process.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for forming 3D NAND flash memory. Background technique [0002] With the development of planar flash memory, the production process of semiconductors has made great progress. However, in recent years, the development of planar flash memory has encountered various challenges: physical limits and existing development technology limits. In this context, in order to solve the difficulties encountered in planar flash memory and to seek lower production costs per unit storage unit, various three-dimensional flash memory structures have emerged as the times require. However, the biggest challenge facing three-dimensional memory is how to increase the storage density per unit area to achieve a lower cost than planar flash memory. [0003] At present, one of the main reasons why 3D NAND is difficult to achieve mass production is that the storage density per ...

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Problems solved by technology

[0003] At present, one of the main reasons why 3D NAND is difficult to achieve mass production is that the storage density per unit area is not high enough, so that the cost per unit storage unit is not superior to that of planar 1Y NAND products, or even higher

For 3D NAND, the method of increasing storage density is mainly by increasing the number of stacked layers, but this method not only increases the difficulty of the process, but also leads to higher reliability requirements of the product

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