SEMICONDUCTOR STORAGE APPARATUS, CONTROL APPARATUS AND CONTROL METHOD

• US 20100265768A1
• Filed: 06/15/2010
• Published: 10/21/2010
• Est. Priority Date: 01/16/2008
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kasuga, Kazunori
• Granted Patent: US 7,978,513 B2
• Time in Patent Office: Days
• US Class Current: 365/185.30
• CPC Class Codes: G06F 11/1072 in multilevel memories
• CPC Class Codes: G11C 11/5628 Programming or writing circuits; Data input circuits
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/10 Programming or data input circuits

Abstract

A semiconductor storage apparatus comprising: a plurality of cells that store data; a threshold determination section that determines, based on management information that is used to manage data, a binary or multiple-valued form by which values are written to a plurality of the individual cells and determines a threshold based on the determined form of values that are to be written to a plurality of the individual cells; and a write section that writes the data to a plurality of the cells on the basis of the threshold determined by the threshold determination section.

Claims

1. A semiconductor storage apparatus comprising:

a plurality of cells that store data;

a threshold determination section that determines, based on management information that is used to manage data, a binary or multiple-valued form by which values are written to a plurality of the individual cells and determines a threshold based on the determined form of values that are to be written to a plurality of the individual cells; and

a write section that writes the data to a plurality of the cells on the basis of the threshold determined by the threshold determination section.

2. The semiconductor storage apparatus according to claim 1, further comprising

a detection section that detects, as the management information, attribute information that is added to the data to indicate attributes of the data, wherein

the threshold determination section determines, based on the attribute information of the data detected by the detection section, a binary or multiple-valued form by which values are written to a plurality of the individual cells.

3. The semiconductor storage apparatus according to claim 2, further comprising

a threshold conversion section that reads, when a threshold of a cell in which the data is stored among a plurality of the cells is not a current threshold determined by the threshold determination section based on the attribute information of the data, data written to a plurality of the cells;

and rewrites the data to a plurality of the cells on the basis of a threshold determined by the threshold determination section based on the attribute information of the written data.

4. The semiconductor storage apparatus according to claim 1, wherein

the management information indicates the number of times data is written by the write section to a plurality of the individual cells.

5. The semiconductor storage apparatus according to claim 1, wherein

the management information indicates the amount of free space on a plurality of the cells.

6. The semiconductor storage apparatus according to claim 1, further comprising

a threshold correction section that determines, when a threshold of a cell in which the data is stored among a plurality of the cells is not a threshold determined by the threshold determination section, that values are written in binary form to the cells and also determines a threshold based on the binary form, wherein

the write section rewrites data to the cells by writing the data to a plurality of the cells on the basis of the threshold determined by the threshold correction section.

7. A control apparatus for controlling a semiconductor storage apparatus that includes a plurality of cells storing data, the control apparatus comprising:

a threshold determination section that determines, based on management information that is used to manage data, a binary or multiple-valued form by which values are written to a plurality of the individual cells and determines a threshold based on the determined form of values that are to be written to a plurality of the individual cells; and

a write section that writes the data to a plurality of the cells on the basis of the threshold determined by the threshold determination section.

8. The control apparatus according to claim 7, further comprising

a detection section that detects, as the management information, attribute information that is added to the data to indicate attributes of the data, wherein

the threshold determination section determines, based on the attribute information of the data detected by the detection section, a binary or multiple-valued form by which values are written to a plurality of the individual cells.

9. The control apparatus according to claim 8, further comprising

a threshold conversion section that reads, when a threshold of a cell in which the data is stored among a plurality of the cells is not a current threshold determined by the threshold determination section based on the attribute information of the data, data written to a plurality of the cells;

and rewrites the data to a plurality of the cells on the basis of a threshold determined by the threshold determination section based on the attribute information of the written data.

10. The control apparatus according to claim 7, wherein

the management information indicates the number of times data is written by the write section to a plurality of the individual cells.

11. The control apparatus according to claim 7, wherein

the management information indicates the amount of free space on a plurality of the cells.

12. The control apparatus according to claim 7, further comprising

a threshold correction section that determines, when a threshold of a cell in which the data is stored among a plurality of the cells is not a threshold determined by the threshold determination section, that values are written in binary form to the cells and also determines a threshold based on the binary form, wherein

the write section rewrites data to the cells by writing the data to a plurality of the cells on the basis of the threshold determined by the threshold correction section.

13. A control method for controlling a semiconductor storage apparatus that includes a plurality of cells storing data, the control method causing the semiconductor storage apparatus to execute:

determining, based on management information that is used to manage data, a binary or multiple-valued form by which values are written to a plurality of the individual cells and determining a threshold based on the determined form of values that are to be written to a plurality of the individual cells; and

writing the data to a plurality of the cells on the basis of the determined threshold.

14. The control method according to claim 13, further causing the semiconductor storage apparatus to execute:

detecting, as the management information, attribute information that is added to the data to indicate attributes of the data; and

determining, based on the detected attribute information of the data, a binary or multiple-valued form by which values are written to a plurality of the individual cells.

15. The control method according to claim 14, further causing the semiconductor storage apparatus to execute

reading, when a threshold of a cell in which the data is stored among a plurality of the cells is not a current threshold determined based on the attribute information of the data, data written to a plurality of the cells;

and rewriting the data to a plurality of the cells on the basis of a threshold determined based on the attribute information of the written data.

16. The control method according to claim 13, wherein

the management information indicates the number of times data is written to a plurality of the individual cells.

17. The control method according to claim 13, wherein

the management information indicates the amount of free space on a plurality of the cells.

18. The control method according to claim 13, further causing the semiconductor storage apparatus to execute:

determining, when a threshold of a cell in which the data is stored among a plurality of the cells is not a determined threshold, that values are written in binary form to the cells and also determining a threshold based on the binary form; and

rewriting data to the cells by writing the data to a plurality of the cells on the basis of the determined threshold.