Research On 3D Flash Test Pattern Based On Error Mode

NAND Flash is a very important type of memory.With the increasing demand for storage capacity,2D NAND Flash has been unable to meet people's needs for flash capacity and reliability,and 3D NAND flash has become the mainstream trend of flash development.However,while 3D NAND flash memory solves the problems of insufficient capacity and poor reliability of 2D flash memory,it also brings new reliability issues.For example,due to manufacturing process limitations,the channel radius of a flash memory with a vertical channel structure cannot be exactly the same;as the number of stacked layers increases and the distance between layers decreases,the interlayer interference of 3D NAND flash memory will also affect 3D NAND Flash reliability.So far,research on the reliability testing of 3D NAND flash memory,especially the research on flash test patterns is relatively small.In order to study the error mode of 3D flash memory and improve the efficiency of flash memory testing,this article briefly introduces the storage unit and array structure of 3D NAND flash memory,and compares the structural differences between 2D NAND flash memory and 3D NAND flash memory.Based on the characteristics of poor data retention and different channel radius of 3D NAND flash,this article designs a checkerboard test pattern,a highest voltage state test pattern,a lowest voltage state test pattern,a zebra test pattern,and a corresponding test process for 3D NAND flash memory.On this flash test platform built on the chip zynq7020,a 3D C-FG flash was tested for endurance,interference,and data retention.Through this testing,the following conclusions and results are obtained: In the endurance test,the highest voltage test pattern can effectively improve the 3D flash memory life test efficiency.Compared with the traditional test pattern,the improvement efficiency is about 16.7%;in the interference test,it passes zebra test pattern realizes the high-speed test of read interference.In the data retention test,by comparing the checkerboard test pattern,the highest voltage test pattern,and the pseudo-random test pattern,it is proved that the charge leakage in the 3D C-FG flash memory affects the flash memory most in the data retention characteristics.Compared with the traditional flash memory test scheme,the test patterns and test methods designed in this paper can effectively improve the test efficiency and achieve the reliability test of flash memory under different error modes.The work in this paper can provide a more efficient test solution for 3D flash memory testing,and provide new ideas and solutions for the study of flash memory error modes.