Methods of programming and reading single-level trapped-charge memory cells using second-bit threshold detection
AssigneeMacronix International Co., Ltd.
InventorTsung Yi Chou
Life of this patent
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Abstract
Methods are disclosed to compensate for a second-bit effect during programming and reading of charge-trapping memory cells having left and right data regions. When only one of the left and right data regions is to be programmed, a two-step programming procedure is performed on the data region to be programmed. When the memory cell is to be read, threshold voltages for the left and right data regions are sensed with a joint decision regarding left and right data bit values being reached depending upon both sensed threshold voltage values.
Claims11
A method of operating a memory cell having first and second data regions, comprising:
- providing first and second bits of data having values corresponding to distinguishable threshold voltages to be programmed into the first and second data regions;
- changing a threshold voltage of the first and second data regions to a second level, when the first and second bits have a first value;
- and
- changing the threshold voltage of the first data region to a first level, when the first and second bits have first and second values, respectively.
A method of reading a memory cell having first and second data regions, comprising:
- sensing a threshold voltage of the first data region;
- comparing the sensed threshold voltage with first and second threshold levels;
- and
- deciding that the first data region is programmed when the sensed threshold voltage is greater the second threshold level.
A method of reading a charge-trapping memory cell having first and second data regions, comprising:
- sensing a threshold voltage of the first data region;
- sensing a threshold voltage of the second data region;
- deciding that the first and second data regions are unprogrammed when the sensed threshold voltages of the first and second data regions are less than a first level;
- and
- deciding that the first and second data regions are programmed when the sensed threshold voltages of the first and second data regions are greater than a second level.
Dependencies are inferred from the claim text.