Flash memory array system including a top gate memory cell
View Patent ↗A memory system includes memory cells arranged in sectors. A decoder corresponding to a sector disables memory cells having a defective top gate. The decoder may include a low voltage or high voltage latch for the disabling. A top gate handling algorithm is included. The memory system may include dynamic top gate coupling. A programming algorithm and waveforms with top gate handling is included.
1. A memory system comprising:
a plurality of memory cells arranged in sectors, each memory cell having a top gate; and
control circuitry coupled to the plurality of memory cells, wherein the control circuitry is configured to program the plurality of memory cells via:
pulling up all unselected bitlines and selected bitlines to a first bias voltage;
pulling up a selected source line to a second bias voltage;
pulling up a selected word line to a bias programming wordline voltage;
pulling up the selected source line to a bias source line programming voltage;
pulling up a selected top gate to a top gate programming voltage;
releasing the selected bitlines from the first bias voltage; and
pulling down the selected bitlines to a stable bias voltage via application of a programming current, wherein the memory cell has complete programming conditions at its terminal.
2. The memory system of claim 1 wherein the control circuitry includes a top gate handling logic circuit.
3. The memory system of claim 2 wherein the memory cells are multilevel memory cells.
4. The memory system of claim 2 wherein the memory cells are tip erased memory cells.
5. The memory system of claim 2 wherein the memory cells are source side injection memory cells.
6. The memory system of claim 5 , wherein each memory cell further comprising:
a floating gate,
a select gate,
wherein said floating gate having a tip adjacent to said select gate for erasing said floating gate through said tip to said select gate.
7. The memory system of claim 5 , wherein each memory cell further comprising:
a floating gate,
wherein said floating gate having a tip adjacent to said top gate for erasing said floating gate through said tip to said top gate.
8. The memory system of claim 1 further comprising:
a plurality of word lines coupled to at least one other individual line.
9. The memory system of claim 1 wherein the control circuitry, at the end of programming, is further configured to:
ramp down the top gate voltage;
ramp down the word line voltage;
ramp down the source line voltage; and
ramp down the voltages on all of the bitlines.
10. The memory system of claim 1 wherein the memory cells are tip erased memory cells.
11. The memory system of claim 10 wherein the top gate line is dynamically coupled to the word line.
12. The memory system of claim 10 wherein the top gate line is floating.
13. The memory system of claim 1 wherein the memory cells are source side injection memory cells.
14. The memory system of claim 13 wherein the top gate line is dynamically coupled to the word line.
15. The memory system of claim 13 wherein the top gate line is floating.
16. The memory system of claim 1 wherein the memory cells are multilevel memory cells.
17. The memory system of claim 16 wherein the top gate line is dynamically coupled to the word line.
18. The memory system of claim 16 wherein the top gate line is floating.
19. The memory system of claim 1 further comprising circuitry configured to provide top gate capacitance loading and/or coupling handling.
20. The memory system of claim 19 wherein the memory cells are multilevel memory cells.
21. The memory system of claim 19 wherein the memory cells are tip erased memory cells.
22. The memory system of claim 19 wherein the memory cells are source side injection memory cells.
23. The memory system of claim 1 wherein the top gates are coupled using dynamic coupling and/or pseudo-dynamic coupling.
24. The memory system of claim 23 wherein the memory cells are multilevel memory cells.
25. The memory system of claim 23 wherein the memory cells are tip erased memory cells.
26. The memory system of claim 23 wherein the memory cells are source side injection memory cells.
27. The memory system of claim 1 wherein the top gate line is dynamically coupled to the word line.
28. The memory system of claim 1 further comprising a first weak driver for driving the word line, and a second weak driver for driving the top gate line.
29. The memory system of claim 1 wherein the top gate line is floating.
30. The memory system of claim 29 wherein the memory cells are multilevel memory cells.