Nonvolatile memory device and method for sensing the same

• US 9,478,302 B2
• Filed: 04/15/2015
• Issued: 10/25/2016
• Est. Priority Date: 08/01/2014
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, Mu-Hui
• Primary Examiner(s): DINH, SON T
• Application Number:
  US14/687,409
• Publication Number:
  US 20160035432A1
• Time in Patent Office: 559 Days
• Field of Search: 365/72, 365/148, 365/158, 365/203, 365/206, 365/207
• US Class Current: 1/1
• CPC Class Codes: G11C 11/1655 Bit-line or column circuits
• CPC Class Codes: G11C 11/1657 Word-line or row circuits
• CPC Class Codes: G11C 11/1659 Cell access
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1677 Verifying circuits or methods
• 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 11/2273 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/5678 using amorphous/crystalline phase transition storage elements
• CPC Class Codes: G11C 13/0002 using resistive RAM [RRAM] elements
• CPC Class Codes: G11C 13/0004 comprising amorphous/crystalline phase transition cells
• CPC Class Codes: G11C 13/0026 Bit-line or column circuits
• CPC Class Codes: G11C 13/0028 Word-line or row circuits
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 16/28 using differential sensing or reference cells, e.g. dummy cells
• CPC Class Codes: G11C 2013/0054 Read is performed on a reference element, e.g. cell, and the reference sensed value is used to compare the sensed value of the selected cell
• CPC Class Codes: G11C 2213/71 Three dimensional array
• CPC Class Codes: G11C 7/065 Differential amplifiers of latching type

Abstract

A nonvolatile memory device includes a first resistive memory cell connected to a first word line, a second resistive memory cell connected to a second word line that is different from the first word line, a clamping unit connected between a sensing node and the first resistive memory cell to provide a clamping bias to the first resistive memory cell, a reference current supplying unit connected to the second resistive memory cell to supply a reference current, and a sense amplifier connected to the sensing node to sense a level change of the sensing node, wherein when the first word line is enabled, the second word line is disabled.

Claims

1. A nonvolatile memory device comprising:

a first resistive memory cell connected to a first word line;

a second resistive memory cell connected to a second word line that is different from the first word line;

a clamping unit connected between a sensing node and the first resistive memory cell and configured to provide a clamping bias to the first resistive memory cell;

a reference current supplying unit connected to the second resistive memory cell and configured to supply a reference current to the second resistive memory cell;

a sense amplifier connected to the sensing node, the sense amplifier being configured to sense a level change of the sensing node;

a controller configured to perform a sensing operation such that when the first word line is enabled, the second word line is disabled; and

a precharge voltage supplying unit configured to supply a precharge voltage to the first resistive memory cell,

wherein the precharge voltage comprises a first precharge voltage and a second precharge voltage, and wherein a time required to provide the second precharge voltage to the first resistive memory cell is longer than a time required to provide the first precharge voltage to the first resistive memory cell.

2. The nonvolatile memory device of claim 1, wherein the first resistive memory cell is connected to a first bit line, and the second resistive memory cell is connected to a second bit line that is different from the first bit line.

3. The nonvolatile memory device of claim 2, wherein the first bit line and the second bit line are in a complementary relationship.

4. The nonvolatile memory device of claim 1, wherein the precharge voltage supplying unit is configured to supply the precharge voltage to the first resistive memory cell a plurality of times.

5. The nonvolatile memory device of claim 1, wherein the precharge voltage supplying unit comprises a first sub-precharge voltage supplying unit configured to provide the first precharge voltage to the first resistive memory cell and a second sub-precharge voltage supplying unit configured to provide the second precharge voltage to the first resistive memory cell.

6. The nonvolatile memory device of claim 1, wherein the reference current supplying unit comprises a current mirror circuit.

7. A nonvolatile memory device comprising:

a first resistive memory cell connected to a first bit line;

a second resistive memory cell connected to a second bit line that is complementary to the first bit line;

a sensing node connected to the first resistive memory cell;

a reference node connected to the second resistive memory cell;

a first clamping unit connected to the bit line, and configured to provide a first clamping bias to the first resistive memory cell;

a reference current supplying unit connected to the reference node and the second resistive memory cell, and configured to supply a reference current;

a sense amplifier connected to the sensing node and the reference node, and configured to compare a sensing level of the sensing node with a reference level of the reference node determined according to operation of the reference current supplying unit; and

a precharge voltage supplying unit configured to supply a precharge voltage to the first resistive memory cell,

the precharge voltage supplying unit comprising a first sub-precharge voltage supplying unit configured to provide a first precharge voltage to the first resistive memory cell, and a second sub-precharge voltage supplying unit configured to provide a second precharge voltage to the first resistive memory cell, wherein a time required to provide the second precharge voltage to the first resistive memory cell is longer than a time required to provide the first precharge voltage to the first resistive memory cell.

8. The nonvolatile memory device of claim 7, wherein the sense amplifier comprises:

a first amplifying circuit configured to amplify a difference in level between the sensing node and the reference node; and

a second amplifying circuit configured to acceleratingly amplify the amplified difference in level between the sensing node and the reference node.

9. The nonvolatile memory device of claim 8, wherein the first amplifying circuit comprises a pair of PMOS transistors cross-coupled between the sensing node and the reference node, and the second amplifying circuit comprises a pair of NMOS transistors cross-coupled between the sensing node and the reference node, and

the sense amplifier comprises a circuit that includes the pair of the PMOS transistors and the pair of the NMOS transistors, or a differential amplifier circuit that operates as a voltage comparator.

10. The nonvolatile memory device of claim 7, wherein the precharge voltage supplying unit is further configured to supply a precharge voltage to the second resistive memory cell, the precharge voltage supplying unit further comprising:

a third sub-precharge voltage supplying unit configured to provide a third precharge voltage to the second resistive memory cell; and

a fourth sub-precharge voltage supplying unit configured to provide a fourth precharge voltage to the second resistive memory cell.

11. A method of sensing a nonvolatile memory device, comprising:

connecting a first resistive memory cell to a first word line;

connecting a second resistive memory cell to a second word line that is different from the first word line;

connecting a clamping unit between a sensing node and the first resistive memory cell to provide a clamping bias to the first resistive memory cell;

connecting a reference current supplying unit to the second resistive memory cell to supply a reference current to the second resistive memory cell;

connecting a sense amplifier to the sensing node to sense a level change of the sensing node,

such that when the first word line is enabled, the second word line is disabled; and

supplying a precharge voltage to the first resistive memory cell,

wherein the precharge voltage comprises a first precharge voltage and a second precharge voltage, and wherein a time required to provide the second precharge voltage to the first resistive memory cell is longer than a time required to provide the first precharge voltage to the first resistive memory cell.

12. The method of claim 11, further comprising:

connecting the first resistive memory cell to a first bit line; and

connecting the second resistive memory cell to a second bit line that is different from the first bit line.

13. The method of claim 12, wherein the first bit line and the second bit line are in a complementary relationship.

14. The method of claim 11, wherein said supplying the precharge voltage comprises supplying the precharge voltage from the precharge voltage supplying unit to the first resistive memory cell a plurality of times.