Nonvolatile semiconductor memory device and data writing method therefor
View Patent ↗In a nonvolatile semiconductor memory device wherein a plurality of threshold voltages are set so as to store multivalued information in one memory cell, data is first written into the memory cell whose threshold voltage is the lowest as a written state from the erase level, and data is successively written into memory cells whose threshold voltages are higher.
1. A nonvolatile memory apparatus comprising:
a central processing unit; and
a nonvolatile memory,
wherein said central processing unit is capable of outputting a plurality of commands, an address, a write enable signal, a clock signal and data,
wherein said commands includes a program command,
wherein said nonvolatile memory comprises a plurality of word lines and a plurality of memory cells each of which has a threshold voltage within one of a plurality of threshold voltage distributions,
wherein one of said threshold voltage distributions is assigned to an erase state and others of said threshold voltage distributions are assigned to program states, respectively,
wherein said nonvolatile memory receives said commands and said address during an enable state of said write enable signal and receives said data in response to said clock signal during a disable state of said write enable signal, and
wherein in an operation of said program command, said nonvolatile memory controls selection of one word line according to said address received from said central processing unit and brings said threshold voltage of memory cells coupled to said selected word line from the erase state threshold voltage distribution to one of program state threshold voltage distributions corresponding to data to be stored in respective ones of said memory cells.
2. A nonvolatile memory apparatus according to claim 1 ,
wherein said central processing unit is capable of outputting said commands during an enable state of a command enable signal and is capable of outputting said address during a disable state of said command enable signal.
3. A nonvolatile memory apparatus according to claim 2 ,
wherein each of said memory cells is capable of storing a two bit data.
4. A nonvolatile memory apparatus according to claim 3 ,
wherein said nonvolatile memory brings said threshold voltage of memory cells to be within that one of the program state threshold voltage distributions having the lowest voltage, firstly.
5. A nonvolatile memory apparatus according to claim 4 ,
wherein said erase state is assigned to that one of said threshold voltage distributions having the highest voltage.
6. A nonvolatile memory apparatus according to claim 2 ,
wherein said nonvolatile memory brings said threshold voltage of memory cells to be within that one of the program state threshold voltage distributions having the lowest voltage, firstly.
7. A nonvolatile memory apparatus according to claim 6 ,
wherein said erase state is assigned to that one of said threshold voltage distributions having the highest voltage.
8. A nonvolatile memory apparatus comprising:
a central processing unit; and
a nonvolatile memory,
wherein said central processing unit is capable of outputting a plurality of commands, an address, a write enable signal, a clock signal and data,
wherein said commands includes a program command,
wherein said nonvolatile memory comprises a plurality of I/O terminals, a plurality of word lines and a plurality of memory cells each of which has a threshold voltage within a plurality of threshold voltage distributions,
wherein one of said threshold voltage distributions is assigned to an erase state and others of said threshold voltage distributions are assigned to program states, respectively,
wherein said nonvolatile memory receives said commands, said address and said data via said I/O terminals, receives said commands and said address in response to a first state of said write enable signal and receives said data in response to said clock signal in a second state of said write enable signal,
wherein in an operation of said program command, said nonvolatile memory controls selection of one word line according to said address received from said central processing unit and brings said threshold voltage of memory cells coupled to said selected word line from the erase state threshold voltage distribution to one of program state threshold voltage distributions corresponding to data to be stored in respective ones of said memory cells.
9. A nonvolatile memory apparatus according to claim 8 ,
wherein said central processing unit is capable of outputting said commands during an enable state of a command enable signal and is capable of outputting said address during a disable state of said command enable signal.
10. A nonvolatile memory apparatus according to claim 9 ,
wherein each of said memory cells is capable of storing a two bit data.
11. A nonvolatile memory apparatus according to claim 10 ,
wherein said nonvolatile memory brings said threshold voltage of memory cells to be within that one of the program state threshold voltage distributions having the lowest voltage, firstly.
12. A nonvolatile memory apparatus according to claim 11 ,
wherein said erase state is assigned to that one of said threshold voltage distributions having the highest voltage.
13. A nonvolatile memory apparatus according to claim 9 ,
wherein said nonvolatile memory brings said threshold voltage of memory cells to be within that one of the program state threshold voltage distributions having the lowest voltage, firstly.
14. A nonvolatile memory apparatus according to claim 13 ,
wherein said erase state is assigned to that one of said threshold voltage distributions having the highest voltage.
15. A nonvolatile memory apparatus according to claim 1 ,
wherein said central processing unit is provided on a semiconductor substrate different from a semiconductor substrate on which said nonvolatile memory is provided.
16. A nonvolatile memory apparatus according to claim 1 ,
wherein said central processing unit is included in a large-scale integration circuit (LSI), and
wherein said LSI is coupled with terminals of said nonvolatile memory.
17. A nonvolatile memory apparatus according to claim 8 ,
wherein said central processing unit is provided on a semiconductor substrate different from a semiconductor substrate on which said nonvolatile memory is provided.
18. A nonvolatile memory apparatus according to claim 17 ,
wherein said central processing unit is a component in a large-scale integration circuit (LSI), said LSI includes connections with the I/O terminals of said nonvolatile memory.
19. A nonvolatile memory apparatus according to claim 8 ,
wherein said central processing unit is included in a large-scale integration circuit (LSI), and
wherein said LSI is coupled with terminals of said nonvolatile memory.
20. A nonvolatile memory apparatus according to claim 1 ,
wherein said program command and said address commence in synchronism with a same pulse edge of successive pulses of said write enable signal, respectively.
21. A nonvolatile memory apparatus according to claim 2 ,
wherein the enable state and the disable state of said command enable signal commence simultaneously with the program command and the data address, respectively.
22. A nonvolatile memory apparatus according to claim 8 ,
wherein said program command and said address commence in synchronism with a same pulse edge of successive pulses of said write enable signal, respectively.
23. A nonvolatile memory apparatus according to claim 9 ,
wherein the enable state and disable state of said command enable signal commence simultaneously with the program command and the data address, respectively.