Method for programming semiconductor memory device

Abstract

A method of programming a semiconductor memory device includes the steps of: grouping memory cells according to levels of threshold voltages to be programmed; programming the memory cell groups by sequentially applying programming voltages to the memory cell groups; and program verifying the Storage unit group.

Description

technical field [0001] Embodiments of the invention generally relate to methods of programming semiconductor memory devices. Background technique [0002] A semiconductor memory operates as a memory bank for storing data therein, from which data is retrieved as needed. Semiconductor memory is generally classified into random access memory (RAM) and read only memory (ROM). RAM cannot retain their data when power is removed and is known as volatile memory. On the other hand, a memory in which data once stored in the ROM can be maintained even if the power supply is interrupted is called a nonvolatile memory. [0003] In order to increase the integration density of semiconductor memory devices, multi-level cells (MLCs) capable of programming to multiple threshold voltage levels have been proposed. In contrast, a memory cell capable of being programmed to a single threshold voltage level is referred to as a single level cell (SLC). [0004] When the number of threshold volta...

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Problems solved by technology

[0005] Due to the capacitive coupling effect of adjacent memory cells in semiconductor memory devices, unintentional shifts in threshold voltage can be caused in such MLCs while programming

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