Memory system including a semiconductor memory having a memory cell and a write circuit configured to write data to the memory cell

1. A memory system comprising:

a nonvolatile semiconductor memory; and

a controller configured to control the nonvolatile semiconductor memory,

wherein

the nonvolatile semiconductor memory includes

at least one memory cell configured to be programmed to store data, the data corresponding to a threshold voltage of the at least one memory cell, and

a write circuit configured to write write data to the at least one memory cell by

applying a program voltage to the at least one memory cell, and

verifying that the write data is stored in the at least one memory cell by comparing the threshold voltage of the at least one memory cell with a first reference voltage corresponding to the write data;

the write circuit is configured to

execute a first programming operation to obtain a value of a write parameter by comparing the threshold voltage of the at least one memory cell with a second reference voltage, the second reference voltage being different from the first reference voltage, and

execute a second programming operation of making the threshold voltage exceed the first reference voltage while varying a level of the program voltage according to the write parameter during one execution of the first programming operation;

the controller is configured to supply, to the write circuit, a first instruction for the first programming operation or a second instruction for the second programming operation;

the nonvolatile semiconductor memory includes a plurality of elements, the plurality of elements being divided into groups; and

the controller includes a first memory and is further configured to

store, into the first memory, values of the write parameter of each of the groups,

supply, to the write circuit, the second instruction to write data into a write target group among the groups and a value of the write parameter of the write target group, the value of the write parameter of the write target group being stored in the first memory,

supply, to the write circuit, the first instruction to write data into a first element in a first group among the groups,

obtain a value of the write parameter of the first element, and

make the first element stay in the first group or join a second group according to a comparison result of the value of the write parameter of the first element obtained by the first programming operation and the values of the write parameter stored in the first memory.

2. The memory system of claim 1 , wherein a level of the program voltage is varied during one execution of the first programming operation.

3. The memory system of claim 1 , wherein

the controller includes a first memory; and

the controller is further configured to obtain the value of the write parameter from the nonvolatile semiconductor memory and store the obtained value of the write parameter into the first memory.

4. The memory system of claim 1 , wherein

the at least one memory cell is one of a plurality of memory cells; and

the write parameter includes a level of the program voltage at a time during the first programming operation and when a highest voltage of threshold voltage distribution of the plurality of memory cells exceeds the second reference voltage.

5. The memory system of claim 1 , wherein

the first instruction includes a first command sequence including a first command for the first programming operation; and

the second instruction includes a second command sequence including a second command for the second programming operation, the second command being different from the first command.

6. The memory system of claim 1 , wherein

one of the first instruction and the second instruction includes a first command sequence including a prefix command; and

the other of the first instruction and the second instruction includes a second command sequence not including the prefix command.

7. The memory system of claim 1 , wherein

the controller is further configured to supply, to the write circuit, the first instruction to write data into the write target group when the value of the write parameter of the write target group is not stored in the first memory.

8. The memory system of claim 1 , wherein

the controller is further configured to create a new group of elements when a write target element does not satisfy group condition of any of the groups, the new group having a group condition satisfied by the write target element.

9. The memory system of claim 1 , wherein the controller is further configured to supply, to the write circuit, the first instruction to write data into a first element in a first group among the groups when the first element does not satisfy a group condition of the first group.

10. The memory system of claim 1 , wherein

the at least one memory cell is one of a plurality of memory cells, the plurality of memory cells being divided into groups; and

the controller is further configured to

execute a program-and-erase cycle for the plurality of memory cells, and

supply, to the write circuit, the first instruction to write data into memory cells in a group among the groups once in a plurality of executions of the program-and-erase cycles in the group.

11. The memory system of claim 1 , wherein the plurality of memory cells are connected to word lines;

the groups further include a third group that includes one or more word lines including a first word line; and

the controller is further configured to supply, to the write circuit, the first instruction to write data into memory cells once in a plurality of executions of the program-and-erase cycle in the third group, the memory cells being in the third group and being connected to the first word line.

12. The memory system of claim 1 , wherein the word lines include a first word line and a last word line,

the word lines are arranged in an order from the first word line to the last word line, and in a case where word lines of the first word-line group are closer to the first word line than word lines of the second word-line group, the first number of executions is smaller than the second number of executions.

13. The memory system of claim 1 ; wherein the word lines are divided into a first tier of word lines and a second tier of word lines, each of the first tier of word lines and the second tier of word lines includes a first word line and a last word line,

word lines in each of the first tier and toe second tier are arranged in an order from the first word line to the East word line,

in a case where word fines of the first word-line group and word lines of the second word-line group belong to the first tier, and a word line of the first word-line group is closer to the first word line of the first tier than the word lines of the second word-line group, the first number of executions is smaller than the second number of executions, and

in a case where the word lines of the first word-line group and the wore lines of the second word-line group belong to the second tier, and a word line of the first word-line group is closer to the first word line of the second tier than the word lines of the second word-line group, the first number of executions is smaller than the second number of executions.

14. A memory system comprising:

a nonvolatile semiconductor memory; and

a controller configured to control the nonvolatile semiconductor memory,

wherein

the nonvolatile semiconductor memory includes

at least one memory cell configured to be programmed to store data, the data corresponding to a threshold voltage of the at least one memory cell, and

a write circuit configured to write write data to the at least one memory cell by

applying a program voltage to the at least one memory cell, and

verifying that the write data is stored in the at least one memory cell by comparing the threshold voltage of the at least one memory cell with a first reference voltage corresponding to the write data;

the write circuit is configured to

execute a first programming operation to obtain a value of a write parameter by comparing the threshold voltage of the at least one memory cell with a second reference voltage, the second reference voltage being different from the first reference voltage, and

execute a second programming operation of making the threshold voltage exceed the first reference voltage while varying a level of the program voltage according to the write parameter during one execution of the first programming operation;

the controller is configured to supply, to the write circuit, a first instruction for the first programming operation or a second instruction for the second programming operation;

the at least one memory cell is one of a plurality of memory cells, the plurality of memory cells being divided into one or more string units;

the string units are commonly connected to word lines;

the word lines are divided into groups;

a first group among the groups includes one or more word lines including a first word line; and

the controller is further configured to supply, to the write circuit, the first instruction to write data into first write target cells among memory cells in the first group and the second instruction to write data into second write target cells and third write target cells, both the second write target cells and the third write target cells being among memory cells in the first group, the first write target cells being connected to the first word line and being included in a first string unit among the string units, the second write target cells being connected to the first word line and being included in a string unit other than the first string unit, the third write target cells being connected to a word line other than the first word line.

15. The memory system of claim 14 , wherein a level of the program voltage is varied during one execution of the first programming operation.

16. The memory system of claim 14 , wherein

the controller includes a first memory; and

the controller is further configured to obtain the value of the write parameter from the nonvolatile semiconductor memory and store the obtained value of the write parameter into the first memory.

17. The memory system of claim 14 , wherein

the at least one memory cell is one of a plurality of memory cells; and

the write parameter includes a level of the program voltage at a time during the first programming operation and when a highest voltage of threshold voltage distribution of the plurality of memory cells exceeds the second reference voltage.

18. The memory system of claim 14 , wherein

the at least one memory cell is one of a plurality of memory cells, the plurality of memory cells being divided into groups; and

the controller is further configured to

execute a program-and-erase cycle for the plurality of memory cells, and

supply, to the write circuit, the first instruction to write data into memory cells in a group among the groups once in a plurality of executions of the program-and-erase cycles in the group.

19. A memory system comprising:

a nonvolatile semiconductor memory; and

a controller configured to control the nonvolatile semiconductor memory,

wherein

the nonvolatile semiconductor memory includes

at least one memory cell configured to be programmed to store data, the data corresponding to a threshold voltage of the at least one memory cell, and

a write circuit configured to write write data to the at least one memory cell by

applying a program voltage to the at least one memory cell, and

verifying that the write data is stored in the at least one memory cell by comparing the threshold voltage of the at least one memory cell with a first reference voltage corresponding to the write data;

the write circuit is configured to

execute a first programming operation to obtain a value of a write parameter by comparing the threshold voltage of the at least one memory cell with a second reference voltage, the second reference voltage being different from the first reference voltage, and

execute a second programming operation of making the threshold voltage exceed the first reference voltage while varying a level of the program voltage according to the write parameter during one execution of the first programming operation;

the controller is configured to supply, to the write circuit, a first instruction for the first programming operation or a second instruction for the second programming operation;

the at least one memory cell is one of a plurality of memory cells, the plurality of memory cells being divided into groups; and

the controller is further configured to

execute a program-and-erase cycle for the plurality of memory cells,

supply, to the write circuit, the first instruction to write data into memory cells in a first group among the groups once at a first sequence number of execution among a first number of executions of the program-and-erase cycle in the first group, and

supply, to the write circuit, the first instruction to write data into memory cells in a second group among the groups once at a second sequence number of execution among the first number of executions of the program-and-erase cycle in the second group, the first sequence number being different from the second sequence number.

20. The memory system of claim 19 , wherein

the plurality of memory cells being connected to word lines, the word lines divided into word line groups, the word line groups including a first word line group and a second word line group;

the controller is further configured to

execute a program-and-erase cycle,

supply, to the write circuit, the first instruction to write data into memory cells connected to the first word line group once in a first number of executions of the program-and-erase cycle for the memory cells connected to the first word line group, and

supply, to the write circuit, the first instruction to write data into memory cells connected to the second word line group once in a second number of executions of the program-and-erase cycle for the memory cells connected to the second word line group, the first number of executions being different from the second number of executions.