Vierra Magen Marcus LLP
Method of reducing hot electron injection type of read disturb in memory
Read disturb is reduced in a charge-trapping memory device such as a 3D memory device by optimizing the channel boosting voltage in an unselected NAND string. A pass voltage applied to the unselected word lines can cause a large gradient in the channel which leads to electron-hole formation and a hot electron injection (HEI) type of read disturb. When the selected word line is close to the source-side of the NAND string, HEI disturb occurs on the drain-side of the selected word line. To avoid this disturb, a spike is provided in the control gate voltage of a drain-side selected gate transistor to temporarily connect the channel to the bit line, lowering the voltage of the associated channel region. A similar approach is used for a drain-side selected word line. The spike may be omitted when the selected word line is mid-range.
SanDisk Technologies Inc.
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Wei Charles Yingda Hong-Yan
Zhao Kwong Dong Chen