Low power high density random access memory flash cells and arrays
First Claim
1. A flash memory comprising:
- an array of rows and columns of floating gate memory cells, each memory cell having a source, a drain, a gate and a floating gate;
the array including a global bit line and a global source line for each column of cells, the rows of cells being grouped in sectors, each sector including a predetermined number of rows, the drains of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global bit line through first access transistors, the sources of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global source line through second access transistors;
the gates of the floating gate memory cells in each row of floating gate memory cells being connected to a respective word line;
circuitry configured to controllably provide a voltage of a first polarity between the gate and the drain of one or more selected cells in a sector to program the selected cell by Fowler Nordheim tunneling without disturbing the state of other cells; and
,to controllably provide a voltage of a second polarity opposite the first polarity between the gate and the drain of one or more selected rows of cells to erase the selected rows of cells by Fowler Nordheim tunneling without disturbing cells in unselected rows of cells.
0 Assignments
0 Petitions
Accused Products
Abstract
Low power high density random access memory flash cells and arrays using Fowler Nordheim (FN) tunneling for both programming and erasing. The memory array is divided into sectors, each sector comprising a predetermined number of rows. The bit lines are similarly segmented, each global bit line being selectively connectable to a local bit line for each sector, each local bit line being connected to the drains of all floating gate cells in a respective column of each sector. The sources of all floating gate cells in a respective column of each sector are connected to a local source line for that sector, the local source lines for each sector being controllably connectable to respective global source lines. Consequently all floating gate cells within a column of a sector are connected in parallel, source to source and drain to drain. Representative programming and erase voltages not disturbing other cells are disclosed.
218 Citations
24 Claims
-
1. A flash memory comprising:
-
an array of rows and columns of floating gate memory cells, each memory cell having a source, a drain, a gate and a floating gate; the array including a global bit line and a global source line for each column of cells, the rows of cells being grouped in sectors, each sector including a predetermined number of rows, the drains of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global bit line through first access transistors, the sources of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global source line through second access transistors; the gates of the floating gate memory cells in each row of floating gate memory cells being connected to a respective word line; circuitry configured to controllably provide a voltage of a first polarity between the gate and the drain of one or more selected cells in a sector to program the selected cell by Fowler Nordheim tunneling without disturbing the state of other cells; and
,to controllably provide a voltage of a second polarity opposite the first polarity between the gate and the drain of one or more selected rows of cells to erase the selected rows of cells by Fowler Nordheim tunneling without disturbing cells in unselected rows of cells. - View Dependent Claims (2, 3, 4, 6, 7)
-
-
5. The flash memory of 1 wherein the number of rows in a sector is 64.
-
8. A flash memory comprising:
-
an array of rows and columns of floating gate memory cells, each memory cell having a source, a drain, a gate and a floating gate; the array including a global bit line and a global source line for each column of cells, the rows of cells being grouped in sectors, each sector including a predetermined number of rows, the drains of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global bit line through first access transistors, the sources of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global source line through second access transistors; the gates of the floating gate memory cells in each row of floating gate memory cells being connected to a respective word line; circuitry configured to controllably provide a voltage of a first polarity between the gate and the drain of one or more selected cells in a sector to program the selected cell by Fowler Nordheim tunneling and restricting voltages on floating gate memory cells not intended to be programmed to lesser voltages not disturbing the state of the floating gate memory cells not intended to be programmed; and
,to controllably provide a voltage of a second polarity opposite the first polarity between the gate and the drain of one or more selected rows of cells to erase the selected rows of cells by Fowler Nordheim tunneling and for restricting voltages on floating gate memory cells not intended to be erased to lesser voltages not disturbing the programming of the floating gate memory cells not intended to be erased. - View Dependent Claims (9, 10, 11)
-
-
12. The flash memory of 8 wherein the number of rows in a sector is 64.
-
13. A low power program and erase flash memory method comprising:
-
providing an array of rows and columns of floating gate memory cells, each memory cell having a source, a drain, a gate and a floating gate, the array including a global bit line and a global source line for each column of cells, the rows of cells being grouped in sectors, each sector including a predetermined number of rows, the drains of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global bit line through first access transistors, the sources of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global source line through second access transistors, the gates of the floating gate memory cells in each row of floating gate memory cells being connected to a respective word line; controllably providing a voltage of a first polarity between the gate and the drain of one or more selected cells in a sector to program the selected cell by Fowler Nordheim tunneling without disturbing the state of other cells; and
,controllably providing a voltage of a second polarity opposite the first polarity between the gate and the drain of one or more selected rows of cells to erase the selected rows of cells by Fowler Nordheim tunneling without disturbing cells in unselected rows of cells. - View Dependent Claims (14, 15, 16, 18, 19)
-
-
17. The method of 13 wherein the number of rows in a sector is 64.
-
20. A low power program and erase flash memory method comprising:
-
providing an array of rows and columns of floating gate memory cells, each memory cell having a source, a drain, a gate and a floating gate, the array including a global bit line and a global source line for each column of cells, the rows of cells being grouped in sectors, each sector including a predetermined number of rows, the drains of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global bit line through first access transistors, the sources of all cells in any selected column of any selected sector being coupled together and controllably couplable to a global source line through second access transistors, the gates of the floating gate memory cells in each row of floating gate memory cells being connected to a respective word line; controllably providing a voltage of a first polarity between the gate and the drain of one or more selected cells in a sector to program the selected cell by Fowler Nordheim tunneling and restricting voltages on floating gate memory cells not intended to be programmed to lesser voltages not disturbing the state of the floating gate memory cells not intended to be programmed; and
,controllably providing a voltage of a second polarity opposite the first polarity between the gate and the drain of one or more selected rows of cells to erase the selected rows of cells by Fowler Nordheim tunneling and restricting voltages on floating gate memory cells not intended to be erased to lesser voltages not disturbing the programming of the floating gate memory cells not intended to be erased. - View Dependent Claims (21, 22, 23)
-
-
24. The method of 20 wherein the number of rows in a sector is 64.
Specification