Vertical gate stacked NAND and row decoder for erase operation
View Patent ↗A three-dimensional integrated circuit non-volatile memory array includes a memory array with multiple vertical gate NAND memory cell strings formed in a different vertical layers over a substrate which share a common set of word lines, where different groupings of NAND memory cell strings formed between dedicated pairings of source line structures and bit line structures form separately erasable blocks which are addressed and erased by applying an erase voltage to the source line structure of the erase block being erased while applying a ground voltage to the other source line structures in the array and a high pass voltage to the bit line structures in the array.
1. A method, comprising:
erasing a first erase block of three-dimensional NAND memory strings by selectively applying a first erase voltage to only a first source line connected to the first erase block of three-dimensional NAND memory strings;
while applying the first erase voltage to the first source line, concurrently applying a second voltage to a second source line connected to a second erase block to prevent erasure of the second erase block, each of the first erase block and the second erase block being separately erasable; and
inputting a row address into a row decoding circuitry, the row decoding circuitry comprising a plurality of pass blocks, and the row address comprising block address bits and page address bits, each pass block comprising a plurality of pass transistors for passing wordline, string select line and source line voltages.
2. The method of claim 1 , wherein the three-dimensional NAND memory strings are vertical gate stacked NAND memory strings and the first erase blocks and the second erase block share a common set of word lines.
3. The method of claim 1 , further comprising, while applying the first and second erase voltages, concurrently applying a high pass voltage to a first string select line connected to the first erase block of the three-dimensional NAND memory strings.
4. The method of claim 2 , further comprising, while applying the first and second erase voltages, concurrently applying a ground voltage to the common set of word lines.
5. The method of claim 1 , wherein erasing the first erase block of three-dimensional NAND memory strings comprises positively charging floating body portions of the three-dimensional NAND memory strings through a hole injection created by applying the first erase voltage to drain or source end portions of the three-dimensional NAND memory strings to create reverse biased junctions in the three-dimensional NAND memory strings.
6. The method of claim 1 , further comprising applying a first block selection signal (SEL_BK) to a first pass block of the plurality of pass blocks, wherein a pair of pass transistors within the first pass block receives the first block selection signal, the pair of pass transistors comprising a pass transistor for a source line and pass transistor for a string select line.
7. The method of claim 1 , further comprising:
decoding the row address to select a first memory array block from a plurality of memory array blocks, each memory array block comprising a plurality of three-dimensional NAND memory cell strings organized as a plurality of separately erasable erase blocks sharing a common set of word lines which are not shared with other memory array blocks;
decoding the row address to select the first erase block of the plurality of separately erasable erase blocks in the selected first memory array block, each erase block comprising a subset of a respective plurality of three-dimensional NAND memory cell strings connected between a separately selectable pairing of a source line and a corresponding string select line; and
respectively applying the first erase voltage and a high pass voltage concurrently to a first source line and its corresponding string select line for the first erase block to erase the plurality of three-dimensional NAND memory cell strings connected between the first source line and the corresponding string select line.