Lithography-friendly local read circuit for NAND flash memory devices and manufacturing method thereof
View Patent ↗A flash memory device comprising a local sensing circuitry is provided in a hierarchical structure with local and global bit lines. The local sensing circuitry comprise read and pass circuits configured to sense and amplify read currents during read operations, wherein the amplified read signals may be passed to a global circuit via the local and global bit lines.
1. A vertical NAND flash device comprising:
a semiconductor substrate;
NAND Flash cells formed in vertical pillars above the semiconductor substrate, the vertical pillars having bottom portions in contact with the semiconductor substrate and top portions;
a bit line connected to the top portions of the vertical pillars; and
a sensing circuit comprising at least three gate electrodes adjacent to each other, the gate electrodes being formed on channel regions, the channel regions being a part of the semiconductor substrate,
wherein the gate electrodes extend in evenly spaced line patterns running perpendicular to the bit line.
2. The vertical NAND flash device of claim 1 , wherein
the bit line is a local bit line, and
the sensing circuit is a local sensing circuit connecting the local bit line to a global bit line.
3. A vertical NAND flash device comprising:
a semiconductor substrate;
a first group of vertical pillars comprising a first vertical pillar and a second vertical pillar;
a second group of vertical pillars comprising a third vertical pillar and a fourth vertical pillar;
NAND Flash cells formed in the first, the second, the third and the fourth vertical pillars above the semiconductor substrate, the vertical pillars having bottom portions being in contact with the semiconductor substrate and top portions;
a source line formed above the semiconductor substrate and between the first and the second groups of vertical pillars, no source line being formed between the first and the second vertical pillar and between the third and the fourth vertical pillar;
a first local metal interconnection in contact with the top portions of the first and the second vertical pillars but not with the top portions of the third and the fourth vertical pillars;
a second local metal interconnection in contact with the top portions of the third and the fourth vertical pillar but not with the top portions of the first and the second vertical pillar; and
a global metal interconnection longer than the first and second local metal interconnections, extending in a direction parallel to the first and second local metal interconnections, and electrically connected to the first local metal interconnection through at least a first contact plug and also to the second local metal interconnection through at least a second contact plug.
4. The vertical NAND flash device of claim 3 , wherein the global metal interconnection is a bit line.
5. The vertical NAND flash device of claim 3 , wherein the source line is at least partially at a same height as gate electrodes formed on the semiconductor substrate.
6. The vertical NAND flash device of claim 3 , further comprising a trench in the semiconductor substrate, the trench being located between the first and the second groups of vertical pillars.
7. The vertical NAND flash device of claim 3 , wherein the vertical pillars are straight vertical pillars.
8. The vertical NAND flash device of claim 3 , wherein the vertical pillars have bent portions.