Method for programming of multi-bit semiconductor memory

Abstract

The invention discloses a method for programming of a multi-bit semiconductor memory, and relates to the technical field of semiconductor memories. The method comprises the following steps: performing reset operation of all memory cells in the multi-bit semiconductor memory; performing a first turn of programming operation, that is programming threshold voltages of all the memory cells in the multi-bit semiconductor memory to be in a voltage range lower by 0.5 volt than the specified threshold voltages of the memory cells; and performing a second turn of programming operation, that is programming the threshold voltages of all the memory cells in the multi-bit semiconductor memory to be in a voltage range of + / - 0.05 volt of the specified threshold voltages of the memory cells. The invention effectively solves the contradiction between memory reset speed and reset precision, on one hand, improves the reset speed of the memory, on the other hand, greatly reduces the distribution scope of the memory cell threshold voltage after reset.

Description

technical field [0001] The invention relates to the technical field of semiconductor memory, in particular to a method for programming a multi-bit semiconductor memory. Background technique [0002] At present, the development of memory technology has become an important driving force for the advancement of integrated circuit design and manufacturing, and occupies a very important position in the field of microelectronics. [0003] Such as figure 1 as shown, figure 1 It is a very important type of semiconductor memory - a schematic diagram of the stack gate non-volatile memory structure. The memory structure includes a silicon substrate (P-sub), n-type heavily doped source region (S) and drain region (D) on the silicon substrate, and a tunnel covering the carrier channel between the source and drain regions. A dielectric layer, a charge storage layer covering the tunnel dielectric layer, a barrier layer covering the charge trapping layer, and a control gate dielectric lay...

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Problems solved by technology

To make the threshold voltages of all memory devices distributed in a narrow range after programming, the pulse amplitude applied during programming should be low, so that after each programming, the threshold voltage of memory devices increases by a small amount, but in this way It will significantly increase the number of programming times for a single cell, thereby greatly increasing the memory programming time; if you want to speed up the memory programming speed and reduce the programming time, you need to apply a larger pulse during programming, so that after each programming, the threshold voltage of the memory cell The increase is relatively large, but this will lead to a large distribution range of the threshold voltage of the memory cell after programming

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