Memory system including the semiconductor memory and a controller
According to one embodiment, a memory system includes a semiconductor memory and a controller. The semiconductor memory includes first blocks including a memory cell capable of storing data of one bit, a second block including a memory cell capable of storing data of two or more bits. The semiconductor memory stores first data in a first latch circuit, and second data in a second latch circuit, and writes the first data into one of the first blocks in page units, and the second data into one of the first blocks in page units. The semiconductor memory writes data of at least two pages into the second block, using the first data stored in the first latch circuit and the second data stored in the second latch circuit.
1. A memory system comprising:
a semiconductor memory capable of storing data; and
a controller configured to control the semiconductor memory,
wherein the semiconductor memory includes:
a plurality of first blocks each including a memory cell capable of storing data of one bit,
a second block including a memory cell capable of storing data of two or more bits, and
a sense amplifier including a first latch circuit and a second latch circuit,
wherein data is written into the semiconductor memory in units of a page by both a first write operation and a second write operation,
wherein in the first write operation,
the controller outputs a set of first data of one page and a first write command, a set of second data of one page and a second write command, and a third write command,
the semiconductor memory stores the first data in the first latch circuit, and the second data in the second latch circuit, and writes the first data into a first one of the first blocks in page units, and the second data into a second one of the first blocks in page units, and when receiving the third write command, the semiconductor memory writes data of at least two pages into the second block, using the first data stored in the first latch circuit and the second data stored in the second latch circuit,
wherein in the second write operation,
after issuing the third write command, the controller issues a first read command, a second read command, and a fourth write command, and
the semiconductor memory reads the first data from the first one of the first blocks to the first latch circuit in response to the first read command; reads the second data from the second one of the first blocks to the second latch circuit in response to the second read command; and overwrites data of at least two pages in the second block written by the first write operation in response to the fourth write command, using the first data and the second data that are read to the first latch circuit and the second latch circuit, respectively,
wherein the fourth write command designates a word line selected in response to the third write command,
a verify voltage that is used when the data of at least two pages is written in response to the fourth write command is higher than a verify voltage that is used when the data of at least two pages is written in response to the third write command, and
each of the first data and the second data includes each of a first bit and a second bit of the data of two or more bits to be written in the memory cell of the second block.
2. The system according to claim 1 , wherein each of the first data and the second data includes each of a first bit and a second bit of the data of two or more bits to be written in the memory cell of the second block.
3. The system according to claim 1 , wherein
the sense amplifier further includes a third latch circuit, and
in the first write operation,
the first data received from the controller is stored in the third circuit and thereafter transferred to the first latch circuit, and
the second data received from the controller is stored in the third latch circuit after the first data is transferred from the third latch circuit to the first latch circuit, and thereafter transferred to the second latch circuit.
4. The system according to claim 1 , wherein
the sense amplifier further includes a third latch circuit,
in the first write operation,
the first data received from the controller is stored in the third latch circuit, and thereafter transferred to the first latch circuit,
the second data received from the controller is stored in the third latch circuit after the first data is transferred from the third latch circuit to the first latch circuit, and thereafter transferred to the second latch circuit, and
in the second write operation,
the first data and the second data read in response to the first read command and the second read command are stored in the first latch circuit and the second latch circuit without passing through the third latch circuit.
5. The system according to claim 4 , wherein
each of the first data and the second data includes each of a first bit and a second bit of the data of two or more bits to be written in the memory cell of the second block, and
the sense amplifier includes the first latch circuit associated in advance with the first bit, and the second latch circuit associated in advance with the second bit.
6. The system according to claim 1 , wherein, if data writing to the first one and/or the second one of the first blocks in response to the first write command and/or the second write command fails, the controller does not issue the third write command.
7. The system according to claim 1 , wherein
the controller issues a status read command to recognize a result of data writing in the semiconductor memory after the controller issues the third write command,
if the data writing to the second block in response to the third write command fails, the controller designates a different address of the second block and re-issues the third write command, and
if the data writing to the first one and/or the second one of the first blocks in response to the first write command and/or the second write command fails, the controller designates a different address in the first one and/or the second one of the first blocks and re-outputs the set of the first data and the first write command and/or the set of the second data and the second write command.
8. The system according to claim 1 , wherein
the controller issues a status read command to recognize a result of data writing in the semiconductor memory after the controller issues the third write command,
if the data writing to the second block in response to the third write command fails, the controller designates a different address of the second block and re-issues the third write command, and the controller designates the different address for a write address for writing data in response to the fourth write command, and
if the data writing to the first one and/or the second one of the first blocks in response to the first write command fails, the controller designates a different address of the first one and/or the second one of the first blocks and re-outputs the set of the first data and the first write command, and the controller designates the different address for a read address for reading data in response to the first read command.
9. The system according to claim 1 , wherein the first one of the first blocks is the same as the second one of the first blocks.
10. The system according to claim 1 , wherein the first data and the second data are written into same one of the first blocks.
11. The system according to claim 1 , wherein the first one of the first blocks is different from the second one of the first blocks.
12. The system according to claim 1 , wherein
a plurality of memory cells are serially connected to form a serial connection in the first blocks and the second block,
one of the memory cells at one end of the serial connection is connected to a source line, and one of the memory cells at the other end of the serial connection is connected to a bit line,
the bit line is connected to the sense amplifier, and
the second write operation for a first memory cell is executed after the first write operation for a second memory cell that is adjacent to the first memory cell on a side of the bit line.
13. The system according to claim 1 , wherein the second write operation is performed without receiving write data from the controller.
14. The system according to claim 1 , wherein the sense amplifier further includes a third latch circuit to hold data received from the controller before the received data is stored in the first latch circuit and the second latch circuit, and
the overwriting the data to the second block in the second write operation is performed without use of the third latch circuit.
15. The system according to claim 1 , wherein a threshold value of a memory cell targeted for data write is increased by overwriting the data into the second block in the second write operation.