Nonvolatile semiconductor memory device

• US 6,791,882 B2
• Filed: 06/21/2002
• Issued: 09/14/2004
• Est. Priority Date: 02/06/1989
• Status: Expired due to Fees

• Current Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Kume, Hitoshi, Wada, Takeshi, Shoji, Kazuyoshi, Seki, Koichi, Muto, Tadashi, Kubota, Yasurou
• Primary Examiner(s): Hoang, Huan
• Application Number:
  US10/175,958
• Publication Number:
  US 20020176282A1
• Time in Patent Office: 816 Days
• Field of Search: 365/185.29, 365/185.08, 365/185.18
• US Class Current: 365/185.29
• CPC Class Codes: G11C 16/06 Auxiliary circuits, e.g. for writing into memory
• CPC Class Codes: G11C 16/12 Programming voltage switching circuits
• CPC Class Codes: G11C 16/16 for erasing blocks, e.g. arrays, words, groups
• CPC Class Codes: G11C 16/30 Power supply circuits
• CPC Class Codes: G11C 16/32 Timing circuits
• CPC Class Codes: G11C 16/344 Arrangements for verifying correct erasure or for detecting overerased cells
• CPC Class Codes: G11C 16/3445 Circuits or methods to verify correct erasure of nonvolatile memory cells
• CPC Class Codes: G11C 2216/20 Suspension of programming or erasing cells in an array in order to read other cells in it

Abstract

An EEPROM having an erasing control circuit that performs at least the read out operation one time on the corresponding memory cells after an erasing operation is performed in connection therewith. The erasing operation is automatically performed by the internal erasing control circuit while the EEPROM is electrically isolated from the microprocessor in response to instructions from the microprocessor. The control by the microprocessor requires only a slightly short period of time during which the erasing commencement is instructed while the EEPROM remains in the system during the erasing operation. In one aspect of the disclosure, a Vcc power source is applied to a source region or a drain region of each nonvolatile semiconductor memory cell, and an erasure voltage having a polarity opposite to that of the Vcc power source is applied to a control gate electrode.

Claims

1. A processing apparatus comprising:

a central processing unit;

a nonvolatile memory;

a volatile memory;

a liquid crystal display;

an input/output port; and

a bus,

wherein said central processing unit is capable of designating either one of an erase operation and a program operation to said nonvolatile memory, via said bus, such that (i) when said erase operation is designated, said nonvolatile memory erases data stored therein, and (ii) when said program operation is designated, said nonvolatile memory stores data therein,

wherein said erase operation includes a threshold voltage moving operation and a verily operation,

wherein said threshold voltage moving operation is that in which a threshold voltage of a memory call in said nonvolatile memory is moved to a threshold voltage range indicating an erase state,

wherein said verify operation determines whether the threshold voltage moving operation of said memory cell to said erase state is completed,

wherein said nonvolatile memory repeats said erase operation when the threshold voltage moving operation of said memory cell to that of an erase state is not yet completed, the erase operation of said nonvolatile memory ending when the threshold voltage of said memory cell is indicative of said erase state, and

wherein said nonvolatile memory is capable of freeing terminals coupled to said bus and said central processing unit is capable of accessing other component parts of said processing apparatus, via said bus, when said erase operation of data stored in said nonvolatile memory is being performed.

2. A processing apparatus according to claim 1,

wherein said central processing unit performs a polling to said nonvolatile memory for detecting whether said erase operation is completed or not.

3. A processing apparatus according to claim 1,

wherein said bus is coupled to said central processing unit, said nonvolatile memory, said volatile memory and said input/output port and is coupled to said liquid crystal display via a controller, and

wherein said nonvolatile memory is capable of performing an erase operation while being operatively decoupled from said bus.

4. A processing apparatus according to claim 3, wherein when performing said erase operation, said nonvolatile memory is decoupled from said bus to enable throughput operation via said bus between said central processing unit and other component parts of said processing apparatus and between different ones of said component parts, and/or with said input/output port.

5. A processing apparatus according to claim 4,

wherein said central processing unit performs a polling to said nonvolatile memory for detecting whether said erase operation is completed or not.

6. A processing apparatus according to claim 3,

wherein said central processing unit performs a polling to said nonvolatile memory for detecting whether said erase operation is completed or not.

7. A processing apparatus according to claim 1, further comprising a regulator circuit,

wherein said regulator circuit generates a voltage for supplying power to said liquid crystal display.

8. A processing apparatus according to claim 1,

wherein said bus includes both an address signal component and a date signal component.

9. A processing apparatus according to claim 1,

wherein said bus is enabled to carry therethrough both address and data signals.

10. A processing apparatus comprising:

a central processing unit;

a flash memory;

a random access memory;

an input/output part; and

a communication link through which a communication link-up is effected of said central processing unit, said flash memory, said random access memory and said input/output port,

wherein said central processing unit is capable of designating either one of an erase operation and a program operation to said flash memory,

wherein said erase operation includes a threshold voltage moving operation and a verify operation,

wherein said threshold voltage moving operation is that in which a threshold voltage of a memory cell in said flash memory is moved to a threshold voltage range indicating an erase state,

wherein said verify operation determines whether the threshold voltage moving operation of said memory cell to said erase state is completed,

wherein said flash memory repeats said erase operation when the threshold voltage moving operation of said memory cell to that of an erase state is not yet completed, the erase operation of said flash memory ending when the threshold voltage of said memory cell is indicative of said erase state,

wherein said flash memory is capable of freeing terminals coupled to said communication link when performing said erase operation, and

wherein said central processing unit is capable of accessing either one of said random access memory and said input/output port when said erase operation is being performed in said flash memory.

11. A processing apparatus according to claim 10, further comprising a display controller,

wherein said communication link includes a bus which is coupled to said central processing unit, said flash memory, said random access memory and said display controller.

12. A processing apparatus according to claim 11, further comprising a display unit,

wherein said display unit is coupled to said bus via said display controller.

13. A processing apparatus according to claim 12,

wherein said bus includes both an address signal component and a data signal component.

14. A processing apparatus according to claim 12,

wherein said bus is enabled to carry therethrough both address and data signals.

15. A processing apparatus according to claim 10,

wherein said communication link includes a bus which is coupled to said central processing unit, said flash memory and said random access memory.

16. A processing apparatus according to claim 15,

wherein said bus includes both an address signal component and a data signal component.

17. A processing apparatus according to claim 15,

wherein said bus is enabled to carry therethrough both address and data signals.

18. A processing apparatus comprising:

a central processing unit;

a flash memory;

a random access memory; and

a bus,

wherein said bus is coupled to said central processing unit, said flash memory and said random access memory,

wherein said central processing unit is capable of designating either one of an erase operation and a program operation to said flash memory,

wherein said erase operation includes a threshold voltage moving operation and a verify operation,

wherein said threshold voltage moving operation is that in which a threshold voltage of a memory cell in said flash memory is moved to a threshold voltage range indicating an erase state,

wherein said verify operation determines whether the threshold voltage moving operation of said memory cell to said erase state is completed,

wherein said flash memory repeats said erase operation when the threshold voltage moving operation of said memory cell to that of an erase state is not yet completed, the erase operation of said flash memory ending when the threshold voltage of said memory cell is indicative of said erase state,

wherein said flash memory is capable at freeing terminals coupled to said bus when performing said erase operation, and

wherein said central processing unit is capable of throughput accessing via said bus of other component parts of said processing apparatus when said erase operation is being performed in said flash memory.

19. A processing apparatus according to claim 18,

wherein said bus includes both an address signal component and a data signal component.

20. A processing apparatus according to claim 18,

wherein said bus is enabled to carry therethrough both address and data signals.