Negative voltage generator, decoder, nonvolatile memory device and memory system using negative voltage

• US 8,705,273 B2
• Filed: 12/13/2011
• Issued: 04/22/2014
• Est. Priority Date: 12/20/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Moosung, Im, Jaewoo, Yu, Jae-Duk, Park, Kitae, Kwon, Ohsuk
• Primary Examiner(s): Ho, Hoai V
• Assistant Examiner(s): HUERTA, PABLO S
• Application Number:
  US13/323,868
• Publication Number:
  US 20120155168A1
• Time in Patent Office: 861 Days
• Field of Search: 365/185.03
• US Class Current: 365/185.03
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 11/5642 Sensing or reading circuits; Data output circuits
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/08 Address circuits; Decoders; Word-line control circuits
• CPC Class Codes: G11C 16/30 Power supply circuits
• CPC Class Codes: G11C 16/3459 Circuits or methods to verify correct programming of nonvolatile memory cells
• CPC Class Codes: G11C 2211/5641 Multilevel memory having cells with different number of storage levels
• CPC Class Codes: G11C 5/14 Power supply arrangements , e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels
• CPC Class Codes: G11C 5/143 Detection of memory cassette insertion or removal; Continuity checks of supply or ground lines; Detection of supply variations, interruptions or levels G11C5/148 takes precedence; Switching between alternative supplies G11C5/141 takes precedence
• CPC Class Codes: G11C 5/145 Applications of charge pumps; Boosted voltage circuits; Clamp circuits therefor G11C5/141 takes precedence
• CPC Class Codes: G11C 5/147 Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops G11C5/141 takes precedence

Abstract

A negative voltage generator includes a direct current voltage generator configured to generate a direct current voltage, a reference voltage generator configured to generate a reference voltage, an oscillator configured to generate an oscillation clock, a charge pump configured to generate a negative voltage in response to a pump clock, and a voltage detector. The voltage detector is configured to detect the negative voltage by comparing a division voltage, obtained by voltage dividing the direct current voltage, with the reference voltage, and to generate the pump clock corresponding to the detected negative voltage based on the oscillation clock.

Claims

1. A nonvolatile memory device comprising:

a voltage generator circuit including a high voltage generator configured to generate a high voltage and a negative voltage generator configured to generate a negative voltage and a well voltage; and

at least one circuit including at least one switch configured to output one of the high voltage and the well voltage in response to an enable signal for applying the negative voltage to a line corresponding to a word line supplied with the negative voltage,

wherein the high voltage generator and the negative voltage generator are configured to generate voltages in response to independent oscillation clocks, respectively,

wherein the high voltage generator comprises;

a reference voltage generator for a high voltage configured to generate a reference voltage for a high voltage;

an oscillator for a high voltage configured to generate a clock for a high voltage;

at least one charge pump configured to generate a target high voltage in response to a pump clock for a high voltage; and

at least one voltage detector configured to detect the target high voltage based on the reference voltage for a high voltage and the clock for a high voltage and to generate the pump clock corresponding to the detected target high voltage,

wherein the at least one voltage detector comprises;

a power supply part for a high voltage connected between a power supply terminal and a detection node for a high voltage supplied with the target high voltage and configured to supply a power supply voltage in response to a high voltage enable signal;

a voltage dividing part for a high voltage connected between the detection node for a high voltage and a comparison node for a high voltage and configured to voltage divide the target high voltage;

a current path forming part for a high voltage connected between the comparison node for a high voltage and a ground terminal and configured to form a current path in response to the high voltage enable signal;

a comparison part for a high voltage configured to compare the reference voltage for a high voltage and a voltage of the comparison node for a high voltage and to generate the pump clock for a high voltage corresponding to the comparison; and

a control part for a high voltage configured to receive the high voltage enable signal and to activate the power supply part and the current path forming part.

2. A nonvolatile memory device comprising:

a voltage generator circuit including a high voltage generator configured to generate a high voltage and a negative voltage generator configured to generate a negative voltage and a well voltage; and

at least one circuit including at least one switch configured to output one of the high voltage and the well voltage in response to an enable signal for applying the negative voltage to a line corresponding to a word line supplied with the negative voltage,

wherein the high voltage generator and the negative voltage generator are configured to generate voltages in response to independent oscillation clocks, respectively,

wherein the high voltage generator comprises;

a reference voltage generator for a high voltage configured to generate a reference voltage for a high voltage;

an oscillator for a high voltage configured to generate a clock for a high voltage;

at least one charge pump configured to generate a target high voltage in response to a pump clock for a high voltage; and

at least one voltage detector configured to detect the target high voltage based on the reference voltage for a high voltage and the clock for a high voltage and to generate the pump clock corresponding to the detected target high voltage,

wherein the voltage generator circuit further comprises a low voltage generator which includes;

a power supply part configured to supply a pump voltage for a peri-voltage according to a comparison result between a voltage of a comparison node for a low voltage and a reference voltage for a low voltage;

a voltage dividing part for a low voltage connected between the comparison node for a low voltage and an output node for a low voltage outputting the peri-voltage and configured to voltage divide the pump voltage for a peri-voltage;

a bias part connected between the comparison node for a low voltage and the ground terminal; and

a comparison part for a low voltage configured to compare a voltage of the comparison node for a low voltage and the reference voltage for a low voltage.

3. A nonvolatile memory device comprising:

a voltage generator circuit including a high voltage generator configured to generate a high voltage and a negative voltage generator configured to generate a negative voltage and a well voltage; and

at least one circuit including at least one switch configured to output one of the high voltage and the well voltage in response to an enable signal for applying the negative voltage to a line corresponding to a word line supplied with the negative voltage,

wherein the high voltage generator and the negative voltage generator are configured to generate voltages in response to independent oscillation clocks, respectively, and

wherein the negative voltage generator comprises;

a direct current voltage generator configured to generate a direct current voltage;

a reference voltage generator configured to generate a reference voltage;

an oscillator configured to generate an oscillation clock;

a charge pump configured to generate the negative voltage in response to a pump clock;

a voltage detector configured to detect the negative voltage based on the direct current voltage, the reference voltage, and the oscillation clock and to generate the pump clock corresponding thereto; and

a word line negative voltage generator configured to receive thee direct current voltage, the reference voltage, and the oscillation clock and to generate a negative word line voltage corresponding to the negative voltage.

4. A nonvolatile memory device comprising:

a voltage generator circuit including a high voltage generator configured to generate a high voltage and a negative voltage generator configured to generate a negative voltage and a well voltage; and

at least one circuit including at least one switch configured to output one of the high voltage and the well voltage in response to an enable signal for applying the negative voltage to a line corresponding to a word line supplied with the negative voltage,

wherein the high voltage generator and the negative voltage generator are configured to generate voltages in response to independent oscillation clocks, respectively, and

wherein the voltage generator circuit further comprises a low voltage generator, and wherein the at least one circuit comprises;

a read verification voltage selecting switch circuit configured to select one of a peri-voltage generated by the low voltage generator and a negative voltage generated by the negative voltage generator as a read verification voltage.

5. The nonvolatile memory device of claim 4, wherein the high voltage generator comprises:

a reference voltage generator for a high voltage configured to generate a reference voltage for a high voltage;

an oscillator for a high voltage configured to generate a clock for a high voltage;

at least one charge pump configured to generate a target high voltage in response to a pump clock for a high voltage; and

at least one voltage detector configured to detect the target high voltage based on the reference voltage for a high voltage and the clock for a high voltage and to generate the pump clock corresponding to the detected target high voltage.

6. The nonvolatile memory device of claim 4, wherein the at least one circuit further comprises:

a word line voltage selecting switch circuit configured to select one of a program voltage generated by the high voltage generator and the read verification voltage selected by the read verification selecting switch circuit as a word line voltage of a selected word line.

7. The nonvolatile memory device of claim 6, wherein the nonvolatile memory device performs a 2-step verification operation during a program operation.

8. The nonvolatile memory device of claim 6, further comprising:

at least one selection line driver circuit configured to provide a corresponding selection line with one of a read pass voltage or a pass voltage output from the high voltage generator and the word line voltage selected by the word line voltage selecting switch circuit.

9. The nonvolatile memory device of claim 8, further comprising a first row decoder and a second row decoder, the first row decoder formed at a first well and driving corresponding word lines with voltages applied to first selection lines, and the second row decoder formed at a second well and driving corresponding word lines with voltages applied to second selection lines.

10. The nonvolatile memory device of claim 9, wherein the at least one switch circuit comprises a selection line selecting switch circuit configured to select whether a plurality of selection lines of the selection line driver is connected to the first selection lines or the second selection lines.

11. The nonvolatile memory device of claim 9, wherein the at least one switch circuit comprises a well voltage selecting switch circuit configured to select whether the well voltage is applied to the first well or the second well.

12. A nonvolatile memory device comprising:

a voltage generator circuit including a high voltage generator configured to generate a high voltage and a negative voltage generator configured to generate a negative voltage and a well voltage; and

at least one circuit including at least one switch configured to output one of the high voltage and the well voltage in response to an enable signal for applying the negative voltage to a line corresponding to a word line supplied with the negative voltage,

wherein the high voltage generator and the negative voltage generator are configured to generate voltages in response to independent oscillation clocks, respectively, and

wherein the nonvolatile memory device has a threshold voltage distribution for storing 2-bit data, the threshold voltage distribution including one erase state and three program states, and at least one of the program states being verified by a negative voltage.

13. The nonvolatile memory device of claim 12, wherein a lower threshold voltage limit of the erase state is −

4V.

14. A row decoder comprising:

a block word line;

a pull-up circuit configured to apply a high voltage to the block word line in response to a voltage transfer enable signal;

a pull-down circuit configured to be shut off from the block word line in response to the voltage transfer enable signal, and to apply a well voltage to the block word line in response to an inverted voltage transfer enable signal which is inverted relative to the voltage transfer enable signal; and

a voltage transfer circuit configured to connect a plurality of selection lines with a plurality of word lines based on a voltage of the block word line,

wherein each of the pull-up circuit and the pull-down circuit is formed of at least one n-type active region formed within a p-type well and the p-type well is included within a deep n-type well.

15. The row decoder of claim 14, wherein the pull-down circuit comprises:

a depletion transistor connected between the block word line and a blocking node and having a gate connected with a power supply terminal; and

a level shifter connected at the blocking node and a well voltage terminal supplied with the well voltage and configured to apply a voltage of the power supply terminal to the blocking node in response to the voltage transfer enable signal and to apply the well voltage to the block node in response to the inverted version voltage transfer enable signal,

wherein when a negative voltage is applied to a word line, the well voltage is the negative voltage.

16. The row decoder of claim 15, wherein the level shifter comprises:

at least one PMOS transistor configured to apply a voltage of the power supply terminal to the blocking node in response to the voltage transfer enable signal; and

at least one NMOS transistor configured to apply a voltage of the well voltage terminal to the blocking node in response to the voltage transfer enable signal,

wherein wells of the depletion transistor and the at least one NMOS transistor are connected with the well voltage terminal.

17. The row decoder of claim 16, wherein the at least one NMOS transistor is a high voltage transistor.

18. The row decoder of claim 16, wherein the at least one NMOS transistor is a low voltage transistor.

19. The row decoder of claim 16, wherein the at least one PMOS transistor is a high voltage transistor, and the at least one NMOS transistor is a high voltage transistor.

20. A nonvolatile memory device comprising:

at least one first voltage applying pass circuit configured to apply a positive voltage to a first line; and

at least one second voltage applying pass circuit configured to apply a negative voltage to a second line,

wherein when the negative voltage is applied to the second line, the negative voltage is applied to a well in which the at least one second voltage applying pass circuit is formed,

wherein the at least one second voltage applying pass circuit comprises;

a selection transistor connected between a line supplied with the negative voltage and the second line; and

a selection switch configured to apply a high voltage or a well voltage to a gate of the selection transistor in response to an enable signal,

wherein when the negative voltage is applied to the second line, the well voltage is the negative voltage.

21. The nonvolatile memory device of claim 20, wherein the selection switch comprises:

a pull-up circuit configured to apply the high voltage to the gate of the selection transistor in response to the enable signal; and

a pull-down circuit configured to be shut off from the gate of the selection transistor in response to the enable signal and to apply the well voltage to the gate of the selection transistor in response to an inverted enable signal which is inverted relative to the enable signal.

22. The nonvolatile memory device of claim 21, wherein the pull-down circuit comprises:

a depletion transistor connected between the gate of the selection transistor and a blocking node and having a gate connected with a power supply node; and

a level shifter connected between a well voltage terminal supplied with the well voltage and the blocking node, and configured to apply a voltage of the power supply terminal to the blocking node in response to the enable signal and to apply the well voltage to the blocking node in response to the enable signal.

23. A memory system comprising:

a nonvolatile memory device; and

a memory controller configured to control the nonvolatile memory device,

wherein the nonvolatile memory device comprises;

a negative voltage generator configured to generator a negative voltage; and

at least one row decoder,

wherein the at least one row decoder comprises a pull-up circuit configured to apply a high voltage to a block word line in response to a voltage transfer enable signal, and a pull-down circuit configured to be shut off from the block word line in response to the voltage transfer enable signal and to apply a well voltage to the block word line in response to an inverted voltage transfer enable signal which is inverted relative to the voltage transfer enable signal, and

wherein each of the pull-up circuit and the pull-down circuit is formed of at least one n-type active region formed within a p-type well and the p-type well is included within a deep n-type well, and

wherein when the negative voltage is supplied to at least one word line, the well voltage is the negative voltage.