Cell bottom node reset in a memory array

• US 10,311,933 B2
• Filed: 08/03/2018
• Issued: 06/04/2019
• Est. Priority Date: 08/10/2017
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Sakurai, Kiyotake, Matsubara, Yasushi
• Primary Examiner(s): Nguyen, Tan T.
• Application Number:
  US16/054,785
• Publication Number:
  US 20190051343A1
• Time in Patent Office: 305 Days
• Field of Search: 365145, 365 65, 365149, 36518523, 36518909, 36518911
• CPC Class Codes: G11C 11/221 using ferroelectric capacitors
• CPC Class Codes: G11C 11/2255 Bit-line or column circuits
• CPC Class Codes: G11C 11/2257 Word-line or row circuits
• CPC Class Codes: G11C 11/2259 Cell access
• CPC Class Codes: G11C 11/2273 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/2275 Writing or programming circuits or methods
• CPC Class Codes: G11C 11/2293 Timing circuits or methods
• CPC Class Codes: G11C 11/2297 Power supply circuits
• CPC Class Codes: G11C 11/5657 using ferroelectric storage elements

Abstract

Methods, systems, and devices for cell bottom node reset in a memory array are described. The memory array may include a plurality of ferroelectric memory cells having a cell bottom node and a cell plate opposite the cell bottom node. A zero voltage may be applied to a plurality of digit lines in the memory array. A plurality of word lines may be activated to electrically coupled the plurality of digit lines to cell bottom node of each of the ferroelectric memory cells. Accordingly, the cell bottom node of each of the ferroelectric memory cells may be reset to the zero voltage.

Claims

1. A method, comprising:

applying a cell bottom (CB) reset signal to a driver coupled with a memory array, the memory array comprising ferroelectric memory cells comprising cell bottom nodes and a cell plates opposite the cell bottom nodes, wherein each of the cell bottom nodes is configured to be electrically coupled with a respective digit line;

applying a voltage from a voltage source to a line of the driver based at least in part on applying the CB reset signal, wherein applying the voltage from the voltage source to the line activates word lines of the memory array and couples the digit lines to the cell bottom nodes.

2. The method of claim 1, further comprising:

determining, based at least in part on applying the CB reset signal, a voltage increase of the line; and

determining that the voltage increase exceeds a threshold voltage value, wherein applying the voltage from the voltage source to the line is based at least in part on the voltage increase exceeding the threshold voltage value.

3. The method of claim 1, further comprising:

isolating the line by ceasing applying the CB reset signal from the driver coupled with the memory array after applying the voltage from the voltage source to the line; and

applying a second voltage from a second voltage source to the line based at least in part on removing the CB reset signal.

4. The method of claim 3, wherein the second voltage is configured to power the memory array.

5. The method of claim 1, wherein the CB reset signal and the voltage from the voltage source are applied concurrently.

6. The method of claim 1, further comprising:

writing a logic value to each of the ferroelectric memory cells after applying the voltage from the voltage source to the line.

7. The method of claim 1, wherein applying the voltage from the voltage source to the line comprises activating equalize lines coupled with the memory array.

8. The method of claim 7, wherein applying the voltage from the voltage source to the line comprises activating a switching component coupled with the voltage source and the line based at least in part on activating the equalize lines.

9. The method of claim 1, wherein applying the voltage from the voltage source to the line of the driver resets the cell bottom nodes to a zero voltage.

10. The method of claim 1, wherein the line comprises a Phase X (FX) line.

11. The method of claim 1, wherein the CB reset signal comprises a power signal configured to initiate a power-up operation of the memory array.

12. An apparatus, comprising:

a memory array comprising ferroelectric memory cells comprising cell bottom nodes and cell plates opposite the cell bottom nodes, wherein each of the cell bottom nodes is configured to be electrically coupled with a respective digit line; and

a driver coupled with the memory array, the driver comprising;

a voltage source;

a line coupled with the voltage source; and

cell bottom (CB) reset line coupled with the voltage source and the line via a selection component, wherein the voltage source is configured to apply a voltage to the line based at least in part on a reset signal being applied to the CB reset line, wherein applying the voltage from the voltage source to the line activates word lines of the memory array and couples the digit lines to the cell bottom nodes.

13. The apparatus of claim 12, wherein the line is coupled with a second selection component, and wherein a gate of the selection component is coupled with a word line of the word lines of the memory array.

14. The apparatus of claim 13, wherein the second selection component is configured to couple the line to the word line when a main word line of the memory array is activated, and wherein the second selection component is configured to ground the line when the main word line of the memory array is deactivated.

15. The apparatus of claim 12, further comprising:

a voltage source selection component coupled with each word line of the memory array, wherein the voltage source selection component is configured to be activated based at least in part on the CB reset signal being applied to the CB reset line.

16. The apparatus of claim 15, further comprising:

a second voltage source coupled with the line and the voltage source selection component, wherein the second voltage source is external to the memory array, and wherein the voltage source is internal to the memory array.

17. An apparatus, comprising:

a driver coupled with a memory array comprising ferroelectric memory cells comprising cell bottom nodes and cell plates opposite the cell bottom nodes, the driver comprising a voltage source, a cell bottom (CB) signal line, and a line; and

a memory controller coupled with the driver, the memory controller operable to;

initiate applying a CB reset signal to the driver; and

initiate applying a voltage from the voltage source to the line based at least in part on initiating applying the CB reset signal, wherein applying the voltage from the voltage source to the line activates word lines of the memory array and couples the digit lines to the cell bottom nodes.

18. The apparatus of claim 17, further comprising:

a second voltage source coupled with the line, wherein the memory controller is operable to;

initiate applying a second voltage from the second voltage source to the line, wherein the voltage from the voltage source is applied to the line based at least in part on applying the second voltage to the line.

19. The apparatus of claim 18, wherein initiating applying the voltage from the voltage source to the line comprises initiating activating equalize lines coupled with the memory array.

20. The apparatus of claim 17, wherein the memory controller is operable to write a physical data “

0”

to each of the ferroelectric memory cells by raising a cell plate voltage of each of the cell plates.