JP2011060415A - Nonvolatile semiconductor storage device and data storage system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor storage device for reading management data at a high-speed. <P>SOLUTION: The nonvolatile semiconductor storage device includes: two-dimensional memory cells storing two or more bits; and a reading means reading data stored in the memory cell. In one bit of data formed of two or more bits stored in the memory cell, the logic of stored data is fixed by reading at one threshold voltage. In the other bits of the data formed of two or more bits stored in the memory cell, the logic of stored data is fixed by reading at two or more threshold voltages. The management data managed by the controller controlling the nonvolatile semiconductor storage device 1 is stored in the bit of the memory cell in which the logic of the stored data is fixed by the reading at the one threshold voltage. The reading means reads the data of the other bits after reading the management data of the bit of the memory cell in which the logic of the stored data is fixed by the reading at the one threshold voltage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrically rewritable nonvolatile semiconductor memory device, and more particularly to a flash memory.

  As a nonvolatile semiconductor memory device, development has progressed from an EPROM that can be erased by ultraviolet rays to an EEPROM that can be electrically erased, and further to a flash memory. This flash memory is excellent in high-speed serial writing / serial reading and has a large storage capacity. Further, the flash memory has a finer processing rule and a multilevel technology for storing a plurality of bits of data in one memory cell (Japanese Patent Laid-Open Nos. 4-119594, 10-92186, 10-334474). With the adoption of No. Gazette), the capacity is increasing at a faster rate than DRAM.

  An outline of this multilevel technology will be described. Conventionally, 1-bit data is stored corresponding to the states of “1” and “0” depending on which of the two states the memory cell takes. In this multilevel technology, for example, in order to store 2 bits, one memory cell can take one of four different states. As a result, 2-bit data is stored by associating the four states with “11”, “10”, “00”, and “01”. When reading 2-bit data stored in one memory cell, three READ operations are performed by applying three word line voltages between four different states as shown in FIG. Need to do.

  In the data storage flash memory, the minimum unit for serial writing / reading is called a sector (or page). Usually, a plurality of memory cells forming an array along one word line from which data is read constitute one sector. In a system using this data storage flash memory, the sector generally includes management data and user data managed by a controller that controls the flash memory. Although this management data varies depending on the system used, for example, a flag indicating whether the sector is a good sector or a bad sector, a flag indicating whether valid data is written in the sector, Data indicating how many times the sector has been written, ECC (Error Correction Code) data on the user data of the sector, and the like.

  In the flash memory, for example, in a 64M AND type flash memory, one sector includes a 512-byte data area and a 16-byte management area. Here, the management data is stored in the management area. In the 256M AND flash memory, one sector is composed of a 2048-byte data area and a 64-byte management area. The reading for each sector requires about 50 μs, and the data transfer after reading requires 50 ns for every 1 byte.

Further, the storage capacity has been increased by increasing the density of the memory cells. However, when memory cells come close to each other, when trying to read adjacent memory cells at the same time, an error occurs due to interference from adjacent bit lines due to the capacitance generated between adjacent bit lines. There is a problem that arises. Regarding this, a method of performing reading of adjacent memory cells in at least two phases can be considered. This is because, in an array of memory cells connected to one word line, the first memory cell is set to 0, and when the numbers 1, 2, and 3 are sequentially numbered, phase 0 (reading out even-numbered memory cells) P0) (FIG. 14A) and phase 1 (P1) (FIG. 14B) for reading out odd-numbered memory cells are read in two phases. As described above, reading of adjacent memory cells is performed in two different phases, thereby preventing bit line interference between adjacent memory cells and preventing erroneous reading.
In the NAND cell unit, a nonvolatile semiconductor memory having means for precharging one of two bit lines adjacent to each other at the time of reading data to a floating state and setting the other to a positive potential ( JP-A-11-176960). However, this nonvolatile semiconductor memory relates to an operation of reading a specific selected cell.

Japanese Patent Laid-Open No. 4-119594 JP-A-10-92186 JP-A-10-334673 Japanese Patent Laid-Open No. 11-176960

  By the way, in a flash memory, data of one sector is read at a time, but it may be required to read only necessary data as fast as possible. In particular, management data relating to a memory cell in one sector is data that is first required by the controller and needs to be read at high speed.

  Further, for example, as shown in FIG. 18, the data of one sector includes a data area (Y000H to Y7FFH) and a management area (Y800H to Y83FH) as shown in FIG. In the actual physical allocation in which the data of one sector is stored in the memory cell, for example, as shown in FIG. However, in the case where reading is performed in two phases (P0, P1) instead of reading adjacent memory cells simultaneously as described above, in order to read management data as shown in FIG. It is necessary to complete two phases. For this reason, when reading the management data, as shown in FIG. 20, data in the data area must also be read, and there is a problem that a reading time for one sector is required.

  Accordingly, an object of the present invention is to provide an electrically rewritable nonvolatile semiconductor memory device that can read out desired data, for example, management data at high speed.

A nonvolatile semiconductor memory device according to the present invention has a two-dimensional array of memory cells storing at least two bits, a plurality of word lines, and a plurality of bit lines orthogonal to the word lines,
The memory cell is a non-volatile semiconductor memory device that exists at the intersection of the word line and the bit line, and writes and reads data by applying a predetermined voltage to the word line and the bit line,
In the array of the memory cells connected to at least one of the word lines, there is provided reading means for reading specific data for every (n−1) memory cells (n is an integer of 2 or more). To do.

The non-volatile semiconductor memory device according to the present invention is the non-volatile semiconductor memory device, wherein (n−1) (n is an n) in an array of the memory cells connected to at least one word line. It further has a writing means for writing specific data for every two or more memory cells.

A nonvolatile semiconductor memory device according to the present invention has a two-dimensional array of memory cells storing at least two bits, a plurality of word lines, and a plurality of bit lines orthogonal to the word lines,
The memory cell is a non-volatile semiconductor memory device that exists at the intersection of the word line and the bit line, and writes and reads data by applying a predetermined voltage to the word line and the bit line,
In the array of the memory cells connected to at least one of the word lines, there is provided reading means for reading specific data for each at least one specific bit of the at least two bits or more of a predetermined memory cell. .

The nonvolatile semiconductor memory device according to the present invention is the nonvolatile semiconductor memory device, wherein the at least two bits of a predetermined memory cell in an array of the memory cells connected to at least one word line. Of the above, it is further characterized by further comprising a writing means for writing specific data for each at least one specific bit.

A nonvolatile semiconductor memory device according to the present invention has a two-dimensional array of memory cells storing at least two bits, a plurality of word lines, and a plurality of bit lines orthogonal to the word lines,
The memory cell is a non-volatile semiconductor memory device that exists at the intersection of the word line and the bit line, and writes and reads data by applying a predetermined voltage to the word line and the bit line,
In an array of the memory cells connected to at least one of the word lines, at least one of the at least two bits is specified for every (n-1) memory cells (n is an integer of 2 or more). It has a reading means for reading specific data for each bit.

The nonvolatile semiconductor memory device according to the present invention is the nonvolatile semiconductor memory device, wherein (n−1) (n is 2) in an array of memory cells connected to at least one word line. Each of the memory cells is further provided with writing means for writing data for each at least one specific bit among the at least two bits or more.

  Furthermore, the non-volatile semiconductor memory device according to the present invention is the non-volatile semiconductor memory device, wherein the reading means receives the command for specifying the memory cell to start reading data from the outside. According to the command, specific data is read from a predetermined memory cell.

  Still further, the nonvolatile semiconductor memory device according to the present invention is the nonvolatile semiconductor memory device, wherein the specific data is management data related to an array of the memory cells connected to the word line. To do.

  The system according to the present invention is characterized in that data is input / output to / from the outside using the nonvolatile semiconductor memory device.

  As described above in detail, according to the nonvolatile semiconductor memory device according to the present invention, every (n−1) memory cells (n is an integer of 2 or more), for example, when n is 2, an even number. Since the reading means for reading specific data by performing phase 0 reading for each memory cell is provided, the speed can be increased to half the time required for reading one sector.

  Further, according to the nonvolatile semiconductor memory device of the present invention, every (n−1) memory cells (n is an integer of 2 or more), for example, when n is 2, every even-numbered memory cell By having a writing means for writing specific data in the memory, desired data can be stored for every other memory cell from a predetermined memory cell, and (n-1) (n is an integer of 2 or more) The speed can be increased to half the time required to read one sector by the reading means for reading specific data for every other memory cell.

  According to the nonvolatile semiconductor memory device of the present invention, a predetermined memory cell can be obtained by performing a read means for reading specific data for each at least one specific bit of a predetermined memory cell, for example, a READ operation capable of determining an upper bit Specific data can be read for each upper bit of the. Thus, for example, in the case of 2-bit storage, specific data can be read out by one READ operation among the three READ operations necessary to determine all 2 bits, so that one sector is read out. The speed can be increased to 1/3 of the time. Further, in the case of 3-bit storage, specific data can be read for each upper bit by only one READ operation out of seven READ operations necessary for determining all bits. The speed can be increased to 7 hours.

  According to the nonvolatile semiconductor memory device of the present invention, the specific data is written for each upper bit of the predetermined memory cell by the writing means for writing the specific data for every at least one specific bit of the predetermined memory cell. be able to. Thus, desired data can be stored for each upper bit of a predetermined memory cell. In reading, specific data can be read for each upper bit of a predetermined memory cell by performing a READ operation that can determine the upper bit. In the case of 2-bit storage, specific data can be read out by one READ operation out of the three READ operations necessary to determine all 2 bits. Can be speeded up. Further, in the case of 3-bit storage, specific data can be read for each upper bit by only one READ operation out of seven READ operations necessary for determining all bits. The speed can be increased to 7 hours.

  According to the nonvolatile semiconductor memory device of the present invention, data is read every (n−1) memory cells (n is an integer of 2 or more), for example, every even-numbered memory cell when n is 2. Perform Phase 0. At the same time, by performing reading means for reading specific data for each at least one specific bit, for example, a READ operation that can determine the upper bit, the specific data can be read for each upper bit of a predetermined memory cell. In other words, since it has a reading means that reads specific data by performing only one phase 0 in a single READ operation, in the case of 2-bit storage, the speed is shortened to 1/6 of the time required to read one sector. it can.

  Further, according to the nonvolatile semiconductor memory device of the present invention, every (n−1) memory cells (n is an integer of 2 or more), for example, when n is 2, every even-numbered memory cell In addition, it is possible to write the specific data for each upper bit of a predetermined memory cell by the writing means for writing the specific data for at least one specific bit. Thus, desired data can be stored for each upper bit of every other memory cell. In reading, it has reading means for reading specific data by performing only phase 0 of one READ operation. As a result, in the case of 2-bit storage, the speed can be increased to 1/6 of the time required for reading one sector.

  Further, according to the nonvolatile semiconductor memory device of the present invention, the memory cell from which the specific data is read can be appropriately changed by inputting a command for specifying the memory cell from which reading is to be started from the outside.

  Furthermore, according to the nonvolatile semiconductor memory device of the present invention, the management data that is first required by the controller can be read at high speed.

  According to the system of the present invention, since data is input / output to / from the outside using the nonvolatile semiconductor memory device, desired data, for example, management data can be read at high speed.

1 is a schematic diagram of a nonvolatile semiconductor memory device according to a first embodiment of the present invention. It is a figure which shows the physical allocation in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 1 of this invention. FIG. 6 is a diagram showing a management data read operation in one sector of the nonvolatile semiconductor memory device according to the first embodiment of the present invention. It is a figure which shows the physical allocation in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 2 of this invention. It is a figure which shows the read-out operation | movement of the management data in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 2 of this invention. It is a figure which shows the physical allocation in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 3 of this invention. It is a figure which shows read-out operation | movement of the management data in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 3 of this invention. It is a figure which shows the physical allocation in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 4 of this invention. It is a figure which shows read-out operation | movement of the management data in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 4 of this invention. It is a figure which shows the read-out operation | movement of the management data in 1 sector of the non-volatile semiconductor memory device concerning Embodiment 5 of this invention. It is the schematic of the data storage system which concerns on Embodiment 6 of this invention. It is a figure which shows an example of the logical allocation of the data storage system which concerns on Embodiment 6 of this invention. It is a figure which shows another example of the logical allocation of the data storage system which concerns on Embodiment 6 of this invention. When reading memory cells arrayed along the word line of the flash memory, it is applied to the bit line when reading adjacent memory cells in two phases ((a) phase 0, (b) phase 1). It is a figure which shows voltage conditions. The figure which shows the combination of a corresponding upper bit and a lower bit from the relationship between the voltage applied to a word line, and the flowing electric current about each of four states, when reading 2 bits data. It is a figure which shows the change of the value of a sense latch and a data latch in three times of READ operation ((a) READ1, (b) READ2, (c) READ3) which reads 2-bit data from a memory cell. FIG. 17A is a diagram showing an outline of an XOR operation for determining a lower bit after READ3 in FIG. 16, and FIG. 17B is a diagram showing a correspondence between an output from each data latch and upper / lower bits. It is a figure which shows the logical allocation in 1 sector of a non-volatile semiconductor memory device. It is a figure which shows an example of the physical allocation in 1 sector of a non-volatile semiconductor memory device. FIG. 20 is a diagram showing a read operation in one sector of the nonvolatile semiconductor memory device of FIG. 19.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG.
FIG. 1 shows a schematic diagram of a nonvolatile semiconductor memory device according to Embodiment 1 of the present invention. This nonvolatile semiconductor memory device 1 has a Y decoder / sense latch 5 between a plurality of memory cells 2a, 2b arranged two-dimensionally, and a Y decoder / data latch 7a above and below the memory cells 2a, 2b. It has a Y decoder / data latch 7b and X decoders 6a and 6b. Further, there are a word line 3 and a bit line 4 orthogonal to the word line, and each memory cell exists at an intersection of the word line 3 and the bit line 4. Further, each memory cell forms an array along the word line 3 extending from the X decoder 6a, and each memory cell is connected to the Y decoder / sense latch 5 and the Y decoder / data latch 7a by the bit line 4. Further, the bit line 4 is connected to the Y decoder / data latch 7b.

The read operation of the nonvolatile semiconductor memory device 1 will be outlined. A read unit (sector) is an array of a plurality of memory cells connected to one word line 3. With respect to the array of memory cells connected to one word line 3, every other memory cell is read in one phase, and is read in two phases in total. Specifically, even-numbered memory cells are read in phase 0, and odd-numbered memory cells are read in phase 1. In addition, three READ operations are performed to read 2-bit data stored in one memory cell. In each READ operation, data is transferred from the bit line extending from each memory cell to the sense latch 5, and the upper bit is output from the data latch 7b and the lower bit is output from the data latch 7a. Of these, the upper bits can be determined by READ1.
Note that the phase of reading the array of memory cells connected to one word line is not limited to twice (P0, P1), and may be divided into n times (n is an integer of 2 or more). . In this case, data is read every (n−1) memory cells.

  The nonvolatile semiconductor memory device 1 also includes a control CPU 8, an ALL determination circuit 9, a command decoder 10, an address decoder 11, and an input / output buffer 12 (FIG. 1). In the nonvolatile semiconductor memory device 1, input / output of data with the outside is performed via the input / output buffer 12, and the input data is written into a memory cell at a predetermined address specified by the address decoder 11. Memorized. Whether or not the writing is successful is determined by the ALL determination circuit 9. The input command is decoded by the command decoder 10, and the control CPU 8 controls the memory cell for writing / reading data.

Here, when memory cells in four different states are arranged from the top to the bottom in descending order of the threshold voltage along one word line (FIG. 16A), the memory cells Consider the case of reading 2-bit storage.
First, in READ1, as shown in FIG. 16A, when reading is performed at a word line voltage of 3.0 V, a current flows in a memory cell having a threshold value lower than the word line voltage. Is latched in the sense latch, and since no current flows in the memory cell having a threshold value higher than the word line voltage, “1” is latched in the sense latch. The latched value is then transferred from the sense latch to the data latch 2. At this time, an inverted value is generated on the output side opposite to the sense side, and the values “0”, “0”, “1”, and “1” from the top are stored in each memory cell in 2 bits. Corresponds to the upper bits (FIG. 16A).
Next, in READ2, as shown in FIG. 16B, when reading is performed at a word line voltage of 4.0 V, a current flows in three memory cells having a threshold value lower than the word line voltage, and therefore “0”. In the memory cell having the highest threshold value, “1” is latched in the sense latch. The latched value is then transferred from the sense latch to the data latch 1.
In READ3, as shown in FIG. 16C, when reading is performed at a word line voltage of 2.0 V, a current flows in one memory cell having a threshold value lower than the word line voltage. “1” is latched in the sense latch in the memory cell whose threshold is higher than the other three word line voltages.

  Next, as shown in FIG. 17A, the sense latch values (“1”, “1”, “1”, “0”) latched by READ3 are transferred to the bit lines, while the data latches The values latched to 1 (“1”, “0”, “0”, “0”) are inverted and transferred to the bit line, and the value (“0”) obtained as a result of the XOR operation on these two values. , “1”, “1”, “0”) are latched in the data latch 1. Next, the values are inverted at the time of output from the data latch 1 and the values (“1”, “0”, “0”, “1”) are output. This corresponds to the lower bits of the 2-bit storage. The value of the lower bit is output together with the data (upper bit) of the data latch 2 (FIG. 17 (b)). When the upper and lower bits are expressed in succession, they are “01”, “00”, “10”, and “11”, which correspond to the four states of the memory cell. Therefore, the 2-bit memory stored in each memory cell is read as one of these values by three READ operations.

Further, FIG. 2 shows the physical allocation of one sector of the nonvolatile semiconductor memory device. In FIG. 2, for the sake of convenience, an array of memory cells along the word line is shown vertically. In FIG. 2, each row shows a logical address stored in a lower bit and an upper bit of one memory cell. For example, management data (Y800H I / O 0, I / O 4) is stored in the lower bit and the upper bit of one memory cell, respectively. Also, in this nonvolatile semiconductor memory device, management data (Y800H I / O 0 to Y83FH I / O 7) is stored for every even-numbered memory cell (displayed as P0) from a predetermined memory cell. Yes.
In this management data, Y800H represents a logical address, Y represents the Y direction, and 800H represents hexadecimal notation (in decimal notation, 8 × 16 × 16 + 0 × 16 + 0 × 16 = 2048) indicates the number of bytes. I / O 0 represents one of I / O pins 0 to 7 for transmitting 8-bit data representing 1 byte. The notation method of the logical address is not limited to the above, and any notation may be used.

  Next, FIG. 3 shows a read operation in one sector of the nonvolatile semiconductor memory device. In this read operation, when a command and an address (SA (1), SA (2)) divided into a high-order bit and a low-order bit are sequentially input to the IO pin, the word line to be read is determined and serial read is performed. Be started. In reading, only the phase 0 of READ1, READ2, and READ3 is performed on the word line. In this nonvolatile semiconductor memory device, since the management data is stored in the even-numbered memory cell (P0), the management data is read by performing only phase 0 of each of READ1, READ2, and READ3. Can be read out. As a result, management data can be read out in 24 μs, which is half of the case of reading out one sector.

Embodiment 2. FIG.
FIG. 4 shows physical allocation in one sector of the nonvolatile semiconductor memory device according to Embodiment 2 of the present invention. This nonvolatile semiconductor memory device is different from the nonvolatile semiconductor memory device according to the first embodiment in that management data is stored in higher bits. This nonvolatile semiconductor memory device solves the problem of prioritizing reading of management data when data is read from a memory cell storing a plurality of bits by a multi-value technology.

  The problem of reading in this multilevel technology will be described. When multiple bits of data are stored in one memory cell by multilevel technology, in order to read out multiple bits of data stored in one memory cell, for example, 2-bit data (four values) is used. If so, three READ operations are required. In addition, when 3 bits of data (8 values) are provided, 7 READ operations are required. In the case of 2-bit storage, 2-bit data stored in one memory cell is not determined unless all three READ operations are performed. In one READ operation, serial reading is performed on memory cells other than the memory cell storing the management data. For this reason, when the necessary management data is read out, it is necessary to read out extra user data and the like, resulting in a problem that a reading time for one sector is required.

  Such stored data consisting of a plurality of bits is defined on the upper bit side and the lower bit side, and at the time of reading, either the upper bit or the lower bit is read and output, and the A nonvolatile semiconductor memory device (Japanese Patent Laid-Open No. 10-11982, Japanese Patent Laid-Open No. 10-11979) having reading means for reading the other bit-side data during output, or a plurality of bit data arranged in a predetermined order In addition, there is a semiconductor memory (Japanese Patent Laid-Open No. 10-334684) that reads sequentially from the bit data string corresponding to the first bit. However, these nonvolatile semiconductor memory devices and semiconductor memories perform serial access without interruption, and do not give priority to reading management data in the management area.

  The nonvolatile semiconductor memory device according to the second embodiment solves the problem of high-speed reading in the multilevel technology described above. In one sector of this nonvolatile semiconductor memory device, for example, Y800H I / O 0 to I / O 7 as management data is stored in the upper bits of consecutive memory cells as shown in FIG. The management data read operation is shown in FIG. In the read operation, READ1 phase 0 and phase 1 are performed. Since the management data (Y800H I / O 0 to Y83FH I / O 7) is stored only in the upper bits of each memory cell from a predetermined memory cell, the management data can be read out by performing only the operation of READ1. it can. Therefore, it is possible to read in 1/3 time as compared with the case where all the sectors are read out. In the case of 3-bit storage, the management data for each upper bit can be read out by one READ operation out of the seven READ operations necessary for determining all bits. Can be speeded up.

Embodiment 3 FIG.
FIG. 6 shows the physical allocation of one sector in the nonvolatile semiconductor memory device according to Embodiment 3 of the present invention. Compared with the nonvolatile semiconductor memory device according to the first and second embodiments, this nonvolatile semiconductor memory device stores management data in higher bits in every other memory cell from a predetermined memory cell. It is different in point. In FIG. 6, for example, the management data (Y800H I / O 0 to I / O 3) is stored in the upper bits of even-numbered memory cells. The read operation is shown in FIG. Since this nonvolatile semiconductor memory device stores data only in even-numbered memory cells (P0) from a predetermined memory cell, only phase 0 needs to be performed. In addition, since management data is stored only in the upper bits, only READ1 needs to be performed. Therefore, management data can be read out by performing only face 0 of READ1, so that the reading time can be shortened to 1/6 of one sector.

Embodiment 4 FIG.
FIG. 8 shows physical allocation of one sector in the nonvolatile semiconductor memory device according to Embodiment 4 of the present invention. This nonvolatile semiconductor memory device is different from the nonvolatile semiconductor memory device according to the second embodiment in that specific data exceeding the size of management data is stored in the upper bits of a predetermined memory cell. In FIG. 8, for example, specific data (Y000H I / O 0 to Y41FH I / O 7) is stored in the upper bits. The size of the specific data is 1056 bytes, which is half of the capacity of one sector at the maximum. The read operation is shown in FIG. Since the specific data is stored in the upper bits of a predetermined memory cell, the READ1 operation for determining the upper bits can be read out in the order of phase 0 and phase 1. As a result, the reading time can be shortened to 1/3 of one sector.
Further, when specific data is stored in the upper bits of every other even-numbered memory cell (P0) from a predetermined memory cell, the specific data can be read out by performing only phase 0 of READ1. Therefore, the read time can be shortened to 1/6 of one sector. In this case, the size of the specific data is 528 bytes which is a quarter of the capacity of one sector at the maximum.

Embodiment 5 FIG.
The physical allocation of one sector in the nonvolatile semiconductor memory device according to Embodiment 5 of the present invention is the same as the physical allocation of one sector in the nonvolatile semiconductor memory device according to Embodiment 4, and is shown in FIG. . This nonvolatile semiconductor memory device stores specific data (Y210H to Y41FH, Y630H to Y83FH) in the upper bits of odd-numbered memory cells. Normally, phase 1 is read after phase 0 is read, but this nonvolatile semiconductor memory device changes the reading order in accordance with an address input from the outside. In this case, when (Y210H to Y41FH, Y630H to Y83FH) is input as an address, reading is performed from Phase 1 for reading odd-numbered memory cells. This enables high-speed reading even for odd-numbered memory cells. In this case, since it is an odd-numbered memory cell that can be read at high speed, specific data up to a storage capacity (1056 bytes) that is half of one sector.
FIG. 10 shows a read operation for reading specific data (Y210H to Y41FH) to the upper bits of odd-numbered memory cells. In this case, when (Y210H to Y41FH) is input as an address, reading is performed from Phase 1 for reading odd-numbered memory cells in the operation of READ1. This enables high-speed reading of the upper bits of the odd-numbered memory cells, and reading of phase 1 of READ1 by an external input address or command reduces the reading time to 1/6 of reading of one sector. can do. In this case, since high-order reading is possible in the upper bits of the odd-numbered memory cells, specific data up to 1/4 storage capacity (528 bytes) of one sector is obtained.

In addition, reading from phase 1 may be performed first by a command input from the outside.
Furthermore, the specific data may be stored in the upper bits that can be determined by READ1. In this case, only high-order bits that can be determined by READ1 can be read at high speed, and therefore, specific data up to half the storage capacity of one sector can be obtained.

Embodiment 6 FIG.
A data storage system according to Embodiment 6 of the present invention is shown in FIG. For this data storage system, the nonvolatile semiconductor memory device according to the present invention can be used. Specifically, any of the nonvolatile semiconductor memory devices according to the first to fifth embodiments can be used. The data storage system 20 includes three flash memories 21, 22, and 23, and includes a controller 24 for controlling them, a buffer 25 that temporarily stores data, and an error correction circuit 26 that performs error correction. In addition, the data storage system 20 stores management data that needs frequent access for use by the controller 24 in the system in a management area for each sector of the nonvolatile semiconductor memory device constituting the system. (FIG. 12).

  The management data can be stored using the specific data storage method in the nonvolatile semiconductor memory device according to the first to fifth embodiments. That is, for an array of memory cells connected to a single word line, management data is stored for every other memory cell, and every other memory cell is read out in two phases. The management data may be read for each memory cell. Alternatively, management data may be stored for each upper bit of a predetermined memory cell, and the management data may be read for each upper bit in one READ operation. Further, the management data may be read for each upper bit for every other memory cell.

In order to handle data exceeding the size of the normal management area (64 bytes) at a higher speed, the physical allocation address for storing data may be variously changed. For example, as shown in FIG. 13, data (# 0000 to # 041F) frequently required by the controller is stored in the upper bits (corresponding to READ1) of even-numbered memory cells (corresponding to phase 0) of one sector. Thus, it is possible to read out by performing only phase 0 of READ1 in the read operation, and it is possible to handle these data at high speed.
Furthermore, when the read operation is performed only in phase 0, the data amount up to half of one sector can be increased to half the time required to read all one sector. Further, in the case of 2-bit storage, when data is stored only in the upper bits that can be determined only by READ1, the data amount up to 1/4 of one sector can be increased to 1/6 of the time required to read out one sector. . As this data storage system, for example, an IC card can be used.
Furthermore, the system for inputting / outputting data to / from the outside using the nonvolatile semiconductor memory device according to the present invention is not limited to this data storage system. In addition to this non-volatile semiconductor device, a control unit including a controller 24, a buffer 25, an error correction circuit 26, etc., an input / output device such as a keyboard and a pointing device, an image input / output device, an audio input / output device, and other equipment A connection device or the like may be included.

P0 Phase 0, P1 Phase 1, 1 Nonvolatile semiconductor memory device, 2 Memory cell, 3 Word line, 4 Sense latch, 5 X decoder, 6a Y decoder / data latch 1, 6b Y decoder / data latch 2, 7 For control CPU, 7a Status register, 8 ALL determination circuit, 9 Command decoder, 10 Address decoder, 11 Input / output buffer, 20 Data storage system, 21, 22, 23 Non-volatile semiconductor memory device, 24 Controller, 25 Buffer, 26 Error correction circuit 27 Host system

Claims (6)

A non-volatile semiconductor device,
The nonvolatile semiconductor device is
A plurality of word lines, a plurality of bit lines orthogonal to the word lines, and a two-dimensional array of memory cells storing at least two bits present at the intersection of the word lines and the bit lines;
Reading means for reading data stored in the memory cell;
With
One bit of the data of 2 bits or more stored in the memory cell is read at a threshold voltage of 1, the logic of the stored data is determined, and 2 bits or more stored in the memory cell The other bits in the data of the data are read with a threshold voltage of 2 or more, and the logic of the stored data is determined.
The management data managed by the controller that controls the nonvolatile semiconductor device is stored in the bit of the memory cell in which the logic of the stored data is determined by reading at the threshold voltage of 1,
The reading means reads out the management data of the bit of the memory cell in which the logic of the stored data is determined by reading at the threshold voltage of 1, and then reads the data of the other bits. Nonvolatile semiconductor memory device.   2. The electrical device according to claim 1, further comprising a writing unit that writes the management data for each bit of a memory cell in which logic of stored data is determined by reading at the threshold voltage of 1. A rewritable nonvolatile semiconductor memory device. A non-volatile semiconductor device,
The nonvolatile semiconductor device is
A plurality of word lines, a plurality of bit lines orthogonal to the word lines, and a two-dimensional array of memory cells storing at least two bits present at the intersection of the word lines and the bit lines;
Read means for reading data divided into n phases for every (n-1) memory cells (n is an integer of 2 or more) in the array of memory cells connected to at least one of the word lines. When,
With
One bit of the data of 2 bits or more stored in the memory cell is read at a threshold voltage of 1, the logic of the stored data is determined, and 2 bits or more stored in the memory cell The other bits in the data of the data are read with a threshold voltage of 2 or more, and the logic of the stored data is determined.
The management data managed by the controller that controls the non-volatile semiconductor device is read at the first threshold voltage in the first phase of the n phases, and the logic of the stored data is determined. Stored in bits of the memory cell,
The reading means stores management data managed by a controller that controls the nonvolatile semiconductor device by reading at the first threshold voltage in the first phase of the n phases. A non-volatile semiconductor memory device, wherein after the management data of the bit of the memory cell in which the logic is determined is read, data of another bit is read.   In an array of the memory cells connected to at least one of the word lines, every (n−1) memory cells (n is an integer of 2 or more) and at the threshold voltage of 1 The nonvolatile semiconductor memory device according to claim 3, further comprising a writing unit that writes the management data for each bit of the memory cell in which a logic of stored data is determined by reading.   When the command for specifying the memory cell for starting the reading of management data managed by the controller that controls the nonvolatile semiconductor device is input from the outside, the reading unit reads the predetermined memory cell from the predetermined memory cell according to the command. The non-volatile semiconductor memory device according to claim 1, wherein management data is read out.   6. A system for inputting / outputting data to / from the outside using the nonvolatile semiconductor memory device according to claim 1.

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