Device to program adjacent storage cells of different NROM cells
A method includes minimizing current leaking through a virtual ground pipe during access of NROM memory cells. The minimizing includes operating two neighboring memory cells generally together, which includes connecting an operation voltage to a shared local bit line of the two neighboring memory cells and connecting the external local bit lines of two neighboring memory cells to a receiving unit, such as a ground supply or two sense amplifiers. Also included is an array performing the method.
1. A nitride read only memory (NROM) non-volatile memory device comprising:
an array of charge trapping type memory cells connected to word lines and local bit lines; said array comprising global bit lines, select transistors connecting said global bit lines to said local bit lines and select lines to activate said select transistors;
circuitry for programming at generally a same time two adjacent storage areas of two different NROM cells which share a local bit line and for reading at generally a same time said two adjacent storage areas;
wherein programming comprises concurrently applying the same programming pulse to the two adjacent storage areas, and wherein said select transistors are organized such that any set of three consecutive local bit lines are connected to three different global bit lines.
2. The device according to claim 1 , wherein said circuitry comprises a decoder unit to provide a programming voltage to said shared local bit line and to connect the two local bit lines neighboring said shared local bit line to a receiving unit.
3. The device according to claim 2 , wherein said decoder unit comprises:
a Y unit to determine a first global bit line to provide said access voltage and to which two global bit lines, neighboring said first global bit line, to connect to said receiving unit and to connect said global bit lines accordingly; and
an X decoder to determine which select lines to activate to connect said first global bit line to said shared local bit line and said neighboring global bit lines to said neighboring local bit lines.
4. The device according to claim 3 , wherein during programming, said programming voltage is sufficient to provide a double programming current and said receiving unit is a close-to-ground supply.
5. The device according to claim 3 , wherein during reading, said programming voltage is a read voltage and said receiving unit is two separate sensing units.
6. The device according to claim 1 , wherein said NROM memory cells are one of the following: dual-bit cells and multi-level cells.
7. A nitride read only memory (NROM) non-volatile memory device comprising:
an array having charge trapping type memory cells connected to word lines and local bit lines; said array comprising global bit lines, select transistors connecting said global bit lines to said local bit lines and select lines to activate said select transistors; and
circuitry for activating, at generally the same time, three global bit lines during programming of two adjacent neighboring storage areas of two different NROM cells which share a local bit line, such that the neighboring storage areas are concurrently programmed to a non-erased state, and for activating said three global bit lines for concurrently reading said two adjacent neighboring storage areas;
wherein programming comprises concurrently applying the same programming pulse to the two adjacent storage areas, and wherein said select transistors are organized such that any set of three consecutive local bit lines are connected to three different global bit lines.
8. The device according to claim 7 , wherein said circuitry comprises a decoder unit to provide a programming voltage to said shared local bit line and to connect the two local bit lines neighboring said shared local bit line to a receiving unit.
9. The device according to claim 8 , wherein
said decoder unit comprises:
a Y unit to determine a first global bit line to provide said access voltage and to which two global bit lines, neighboring said first global bit line, to connect to said receiving unit and to connect said global bit lines accordingly; and
an X decoder to determine which select lines to activate to connect said first global bit line to said shared local bit line and said neighboring global bit lines to said neighboring local bit lines.
10. The device according to claim 9 , wherein during programming, said programming voltage is sufficient to provide a double programming current and said receiving unit is a close-to-ground supply.
11. The device according to claim 9 , wherein during reading, said programming voltage is a read voltage and said receiving unit is two separate sensing units.
12. The device according to claim 7 , wherein said memory cells are one of the following: dual-bit cells and multi-level cells.