Read voltage optimization method of memory cell, controller of 3D memory and operation method of controller

Abstract

The invention discloses a reading voltage optimization method of a memory cell. The memory cell is selected from a plurality of memory cells corresponding to a selected physical page. The read voltage optimization method comprises the following steps: counting the number of memory cells with a first threshold voltage to obtain a first number; counting the number of the memory cells with the second threshold voltage to obtain a second number; setting an optimal reading voltage based on the first number, the second number and the adjustment parameter, wherein different adjusting parameters are set according to different data storage time, read interference, cross temperature and programming / erasing times. According to the reading voltage optimization method of the memory cell, the controller of the 3D memory and the operation method of the controller, when the optimal reading voltage is set, only the limited number of times of reading is needed, the time delay for determining the optimal reading voltage is effectively reduced, and the adjustment parameters are set based on parameters such as reading interference and programming / erasing times, and the accuracy and reliability of products are improved.

Description

technical field [0001] The invention relates to memory technology, in particular to a method for optimizing the reading voltage of a memory unit, a controller of a 3D memory and an operation method thereof. Background technique [0002] The improvement of the storage density of the memory device is closely related to the progress of the semiconductor manufacturing process. As the feature size of the semiconductor manufacturing process becomes smaller and smaller, the storage density of the memory device becomes higher and higher. In order to further increase storage density, memory devices with a three-dimensional structure (ie, 3D memory devices) have been developed. A 3D memory device includes a plurality of memory cells stacked in a vertical direction, which can double the integration level on a wafer per unit area and reduce the cost. [0003] The 3D memory device is mainly used as a non-volatile flash memory. The two main non-volatile flash memory technologies use NA...

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Problems solved by technology

[0005] In actual use, due to the influence of read disturbance (read disturbance), program / erase times (P / E), cross temperature (cross temperature), data retention time (data retention), etc., the threshold voltage distribution in the memory cell is shifted Or widen, still using the initial read voltage to read data is more error-prone and reduces the reliability of read data. It is necessary to determine the optimal read voltage according to the current state of the 3D memory to reduce the probability of error

In the prior art, in order to determine the optimal reading voltage, it is necessary to read the voltage multiple times and perform calculations, the delay is significantly increased, and the reading speed of the 3D memory is reduced. Therefore, it is expected that a method that can quickly determine the optimal reading voltage 3D memory and its optimal read voltage acquisition method

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