JP5127435B2 - Semiconductor memory device - Google Patents

Description

  The present invention relates to a semiconductor memory device including a dynamic random access memory (DRAM).

  Increasing the speed of semiconductor memories in recent years, especially embedded memories used in system LSIs, has become an important issue. As one means for solving this problem, there is a technique for logically determining the timing for amplifying data on a bit line read from a memory cell by a sense amplifier using a replica circuit. This technique enables optimization of the timing margin and can cope with the influence of external conditions and process variations.

  FIG. 15 shows a circuit configuration including a conventional DRAM replica circuit. This is because the memory cells MC each composed of one transistor and one capacitor, the word lines WL0 and WL1, the bit line pairs BL0 to BLn / XBL0 to XBLn, and the bit line pairs BL0 to BLn / XBL0. Sense amplifiers SA0 to SAn that amplify data of XBLn, dummy memory cells DMC, dummy word lines DWL, dummy bit line pairs DBL / XDBL, and data of the dummy bit line pairs DBL and XDBL are detected and signals are output. A generated data detection circuit 201 and an SA control generation circuit 202 for activating the sense amplifiers SA0 to SAn are provided (see, for example, Patent Document 1).

  The core operation of the conventional semiconductor memory device configured as described above will be described with reference to the timing chart of FIG. First, when there is an access request to the DRAM, the selected word line WL0 is activated and charges from the memory cells are transferred to the bit lines BL0 to BLn. At this time, the dummy word line DWL is also activated, so that charges are similarly transferred to the dummy bit line DBL. When the potential level fluctuation of the dummy bit line DBL due to the charge transfer operation exceeds the threshold value of the data detection circuit 201, the SA control generation circuit 202 is activated and the SA control signal SEN is generated. The sense amplifier SA is activated by this signal, and the bit line pair BL / XBL can be amplified to a desired potential.

Thus, by logically determining the timing until the amplification of the bit line data by using the dummy memory cell, the malfunction of the circuit can be eliminated and the timing can be optimized, so that the timing operation can be speeded up.
JP-A-6-176568

  However, according to the conventional configuration, there is a problem that the level detection based on electric charges cannot perform a correct circuit operation when the potential change does not exceed the threshold value. In particular, in the case of a very small capacity such as a memory cell, the problem cannot be ignored due to the influence of process variations and leakage current.

  Further, when the set threshold value uses, for example, a transistor threshold value, the potential becomes very large compared to the potential change that appears on the bit line from the normal memory cell. For example, the charge amount of the dummy memory cell and the parasitic capacitance of the bit line Due to the reduction or the like, it is necessary to have a layout configuration greatly different from that of a normal memory cell array. This causes a problem that it becomes difficult for the replica circuit to make an accurate timing for starting the sense amplifier.

  In addition, when reading out a fine potential difference using a reference potential or the like, there is a problem that the design of a circuit that generates a reference potential that can cope with process variations and external conditions must be realized, and in order to arrange the reference circuit There were problems such as area overhead.

  Further, in a circuit configuration that requires three memory cell operations such as 1) charge read operation, 2) sense and restore operation, and 3) precharge operation, such as DRAM, even if the timing of only the charge read operation is increased, the memory There has been a problem that neither the speeding up of the operation of the entire cell nor the speeding up of the access time has a significant effect.

  In addition, unlike a circuit configuration in which data is read by transferring current to a bit line, such as a static random access memory (SRAM), a memory cell capacity in a memory such as a DRAM that stores data with electric charge. Since the number of memory cells connected to one bit line is limited by the capacitance ratio between the parasitic capacitance of the bit line and the sense amplifier sensitivity, the memory by freely changing the number of memory cells connected to the bit line, that is, the number of word lines Even in the lineup of capacitors (for example, when the number of word lines is 16 to 512 and the number of bit lines is 512, variations of the memory capacity of 8 Kbit to 256 Kbit can be developed), the replica circuit is used according to the memory capacity. Generate optimal sense amplifier start timing and replica Is a trade-off between road area overhead had a problem not expect a large effect so.

  Further, when the memory capacity is large and various specifications need to be developed as in the case of the embedded memory, especially the embedded DRAM, it is connected to the bit line rather than changing the number of memory cells connected to the bit line depending on the memory capacity. A sense amplifier that amplifies the bit line is realized by changing the number of memory arrays including bit lines without changing the number of memory cells, because it is more effective in terms of stability of circuit operation and reduction in circuit area. Rather than logically determining the start timing of the amplifier, the logical decision of the start timing of the sense amplifier that amplifies the data line that greatly changes the wiring length and load according to the memory capacity is only a problem for speeding up. However, it was important for easily realizing various memory specifications.

  The present invention solves the above-mentioned problem, and changes the speed according to the memory capacity, and the access timing of the sense amplifier that amplifies the data line that amplifies the data load that is the heaviest in the data access time is logically determined. An object of the present invention is to provide a semiconductor memory device that can realize time and can easily realize various memory specifications.

  In order to solve this problem, a semiconductor memory device of the present invention includes a memory cell, a word line and a bit line connected to the memory cell, a first sense amplifier connected to the bit line, a dummy memory cell, and a dummy memory cell. A dummy bit line connected to the second sense amplifier, a second sense amplifier connected to the dummy bit line, a data line connected to the first sense amplifier, a third sense amplifier connected to the data line, and a dummy data connected to the second sense amplifier. And a logic circuit connected to a dummy data line, wherein an output signal of the logic circuit is an input signal for starting a third sense amplifier.

  Further, the logic circuit detects that the static data generated by the second sense amplifier that amplifies the dynamic data read out to the dummy bit line exceeds the switching potential of the transistor at the potential on the dummy data line. The output signal is an input signal for starting the third sense amplifier.

  As described above, the replica circuit configuration for generating the timing of the third sense amplifier for amplifying the data line using the potential level on the dummy data line amplified and transferred by the second sense amplifier allows the memory capacity to be increased. It is possible to generate the optimum transfer timing of the data line whose load greatly changes every time.

  Further, in the configuration in which the current is passed through the dummy data line using the second sense amplifier and the logic circuit detects, the circuit operation failure such that the threshold value of the detection circuit is not exceeded and the layout configuration of the dummy circuit portion do not change significantly. Independent of process variations and external conditions.

  In addition, since the word line connected to the dummy memory cell and the word line connected to the memory cell are the same wiring, the overhead of the replica circuit area is eliminated, and startup from a location physically close to the accessed memory cell is possible. Timing errors can be reduced to create timing.

  In addition, the dummy memory cell is arranged adjacent to the row decoder including the word driver, and has a delay circuit that adjusts the output timing of the logic circuit, so that the start timing of the third sense amplifier can be generated earliest. The access time can be increased, and the activation timing of the third sense amplifier can be finely adjusted by the delay circuit, so that a malfunction due to too early timing can be prevented.

  Further, when two or more second sense amplifiers are connected to the dummy data line by a switch, when the threshold level of the logic circuit and the threshold level of the third sense amplifier are, for example, 4: 1, the second sense amplifier is set to 4 By connecting them individually, it is possible to realize the optimum activation timing of the third sense amplifier.

  In addition, a logic circuit having a function of taking a logical sum of two or more dummy data lines is provided, and data of two or more dummy data lines have the same logic value. As described above, the start timing of the third sense amplifier is generated by the logical sum of the dummy data, so that the start timing signal of the third sense amplifier is not generated even if an erroneous signal is transferred to one dummy data line. That can be eliminated.

  Furthermore, by adopting a redundant configuration, when a word line, a memory cell connected to the word line, or a dummy memory cell is defective, the memory can be relieved by replacing it with a redundant word line.

  Further, by providing means for reading out data of the dummy memory cell to the outside, it is possible to determine whether or not the data line replica circuit is defective.

  As described above, according to the present invention, a high-speed access time is realized by logically determining the start timing of the sense amplifier that amplifies the data line that varies depending on the memory capacity and has the heaviest load on the data access time. It is possible to provide a semiconductor memory device that can easily realize various memory specifications.

  The best mode for carrying out the present invention will be described with reference to the drawings.

<< First Embodiment >>
FIG. 1 is a block diagram showing the main configuration of the semiconductor memory device according to the first embodiment of the present invention. In FIG. 1, 1 is a memory array including a memory cell composed of one transistor and one capacitor, a word line and a bit line connected to the memory cell, and a sense amplifier connected to the bit line. A dummy memory cell composed of one transistor and one capacitor (even if the circuit configuration is the same as that of one transistor and one capacitor constituting the memory cell, or different from the memory cell) And a dummy memory array including a word line and a dummy bit line connected to the dummy memory cell and a sense amplifier connected to the dummy bit line, and 3 selects and activates a word line connected to the memory cell and the dummy memory cell. A row decoder 4 for data access, and data 4 for data access to the memory array 1 Precharge circuit for precharging line pair DL <m: 0> / XDL <m: 0>, 5 for precharging dummy data line pair DDL / XDDL for data access to dummy memory array 2 A precharge circuit 6 is a circuit block including a write buffer for writing data to the data line pair DL <m: 0> / XDL <m: 0> and a data line sense amplifier for amplifying when data is read. (Data line sense amplifier / write buffer) 7 is a data line sense amplifier control signal generation logic for generating a signal for activating the data line sense amplifier 6 when the potential of the dummy data line DDL exceeds a certain threshold value. A circuit 8 is a control circuit for controlling the memory operation.

  FIG. 2 shows a specific circuit configuration of the memory array 1, the dummy memory array 2, and the row decoder 3. Here, the number of memory cells connected to the bit line of the memory array 1 and the number of dummy memory cells connected to the dummy bit line of the dummy memory array 2 depends on the capacitance ratio between the cell capacitance and the parasitic capacitance of the bit line or dummy bit line, and the sense. The number is determined by the amplifier sensitivity and the required memory speed.

  FIG. 3 shows a specific circuit configuration of the data line sense amplifier / write buffer 6. In FIG. 3, 61 is a data line sense amplifier, and 62 is a write buffer.

  FIG. 4 shows the data line sense amplifier control signal generation logic circuit 7. In FIG. 4, 71 is a NOR circuit, and 72 is a dummy write buffer.

  The replica circuit operation of the dummy memory cell of the semiconductor memory device configured as described above will be described using the timing chart of FIG. First, when there is a read request in the memory, the control circuit 8 generates a read operation reference signal REA to transmit the input address signal to the row decoder 3, and the selected word line WL0 is activated by the decode signal. As a result, data is transferred from the memory cell MC to the bit line BL. At the same time, L data is transferred from the dummy memory cell DMC to the dummy bit line DBL. As a result, the potential of the dummy bit line DBL precharged to ½ of the power supply voltage VDD (or H level) increases in the L level direction by the cell capacitance ratio of the dummy bit line BL and the dummy memory cell DMC. At the same time, a peripheral circuit read operation reference signal RE is also generated.

  Next, after a predetermined time delay for transferring charges from the memory cell MC and the dummy memory cell DMC, the sense amplifiers SA0 to SAn and DSA0 and DSA1 connected to the bit line BL / XBL and the dummy bit line DBL / XDBL are activated. The signal SEN to be activated becomes H level and activated. As a result, the bit lines BL / XBL are amplified to the H or L level, respectively. At the same time, the dummy bit line DBL is amplified to L level. The sense amplifiers SA0 to SAn and DSA0 and DSA1 may use sense amplifiers of the same circuit in order to equalize the process pattern and eliminate variations in the sense operation timing of the bit lines and the dummy bit lines. It goes without saying that sense amplifiers SA0 to SAn and DSA0 and DSA1 may use sense amplifiers having different circuit configurations.

  Next, the column switch signal CS0 for transferring the data of the bit line BL / XBL and the dummy bit line DBL / XDBL to the data line DL / XDL and the dummy data line DDL / XDDL precharged to the power supply voltage VDD is at the H level. By being activated, the desired data from the bit line BL / XBL is transferred to the data line DL / XDL, and the L level data of the dummy bit line DBL is transferred to the dummy data line DDL, respectively. The L level data amplified by the DSA 0 brings the dummy data line DDL to a potential of 1/2 VDD level after a predetermined time. The dummy data line DDL is connected to one input of the NOR circuit 71 of the data line sense amplifier control signal generation logic circuit 7, and the switching level of the CMOS transistor connected to this input signal is 1/2 VDD (ie, the CMOS transistor). And the other input of the NOR circuit 71 is an inverted signal of the H level signal of the peripheral circuit read operation reference signal RE. Therefore, the data line sense amplifier control signal generation logic circuit 7 is inverted. Output signal DACNT becomes H level and the replica circuit operation is completed.

  Next, when the signal DACNT becomes H level, the data line sense amplifier 6 is activated, and the data on the data line DL / XDL is amplified to become H level and L level, respectively. The read operation is performed by transferring the amplified data on the data line DL to the output DO through the buffer circuit.

  Finally, when the read operation reference signal REA and the peripheral circuit read operation reference signal RE become L level after a certain period, the internal circuit of the memory enters a standby state ready for the next operation.

  As described above, when the potential change does not exceed the threshold due to charge transfer, the expected operation cannot be performed again, and the sense amplifier activation timing for amplifying the data of the bit line with the fixed load capacitance is, for example, a transistor By using a fixed delay time such as a delay circuit and performing data transfer with current using a sense amplifier, a desired potential can always be obtained after a certain time, and the data of the data line whose load capacity varies greatly depending on the memory capacity The sense amplifier start-up timing for amplifying the data is a dummy bit line, sense amplifier, column switch, dummy data line and NOR circuit, which are realized with the same circuit configuration from the memory cell, bit line, sense amplifier, column switch, and data line. The output of a replica circuit configured by a simple level detection circuit such as For example, when the memory capacity is reduced, that is, when the circuit load is reduced by shortening the data line, the time until the dummy data line becomes a potential of 1/2 VDD is shortened. Since the activation of the data line sense amplifier is accelerated, the data output, that is, the access time can be increased. Further, for example, when the memory capacity is increased, that is, when the data line load is heavy, a predetermined time is increased to amplify the data line, so that the delay circuit is easily affected by process variations and external conditions. This is an effective means that can realize a data line sense amplifier start-up that is more stable and faster than the timing generation circuit using the.

  Although the NOR circuit 71 is used in FIG. 4, it is needless to say that the circuit configuration can be realized by a simple circuit operation such as a switching function of a CMOS transistor. In addition, it is important in terms of timing optimization to load the dummy data line with the same load transistor as the data line sense amplifier 61.

  In addition, the memory cell and the dummy memory cell having one transistor and one capacitor structure are effective means for increasing the speed when the stored data is dynamic data. However, the dynamic data is stored in the memory cell. For example, two transistors and two capacitors may be used.

  In addition, since the word line connected to the memory cell and the dummy memory cell is made common, it is not necessary to form a dummy word line for the replica circuit, so that the circuit area can be reduced and the memory cell for the same word line can be reduced. Since the gates of the access transistors of the dummy memory cell can be activated at the same timing, the timing at which data is transferred to the bit line and the dummy bit line can be made the same timing. That is, the operation timing of the replica circuit is optimal. Also, the refresh operation required for the capacitor cell is effective because it is connected to the same word line, so that the dummy memory cell can be refreshed at the same time as the memory cell is refreshed, so that only the dummy memory cell does not require a special refresh operation. Means. Needless to say, the memory cell and the dummy memory cell may be connected to different word lines.

  In addition, when the bit line, the dummy bit line, the data line, and the dummy data line are arranged in parallel, the bit line, the dummy bit line, the data line, and the dummy data line are arranged vertically. As compared with, the load of the dummy data line and the load of the data line can be made equal, so that the timing generation by the replica circuit including the dummy data line is effective because the amplification timing of the data line can be optimized. In this specification, reference is made to the relationship between the bit line and the data line. However, if the replica circuit configuration has been changed to static data, even if the data line is connected directly to the bit line via a switch, the data It goes without saying that a replica circuit configuration in a data line connected to the line via a switch may be used.

  Further, when the dummy memory array 2 is arranged adjacent to the row decoder 3 as shown in FIG. 1, a delay circuit for adjusting the output timing of the output signal DACNT of the data line sense amplifier control signal generation logic circuit 7 is provided. As compared with the case where the dummy memory cell is located at the other place, for example, the place farthest from the row decoder 3, the operation timing of the circuit is the earliest, so the timing until the data output is the earliest. This is effective for speeding up the memory. In addition, as a countermeasure for preventing malfunction when the output timing is too early, it is effective to arrange a delay circuit for fine adjustment of timing. Needless to say, the means for adjusting the delay circuit using a fuse or a non-volatile memory is effective because the mask is not changed.

  In addition, since the adjacent capacitor of the dummy memory cell is joined to increase the amount of charge read to the bit line, a stable sense amplifier operation can be realized, which is effective as guaranteeing the operation of the replica circuit. . Needless to say, the dummy memory cell may have a larger capacitor than the memory cell, and a new capacitor may be formed even when the dummy memory cell is realized by short-circuiting the electrode of the capacitor.

  In addition, since the same number of memory arrays 1 and dummy memory arrays 2 are arranged as shown in FIG. 1, the replica circuit can be activated from a location where the respective arrays of the selected word lines are physically aligned with a certain position. It is an effective means that can generate optimal timing. Further, by connecting the word line in common between the memory array 1 and the dummy memory array 2, dummy memory cells and memory cell data are read from the selected word line, so that more optimal timing can be generated. Further, if the dummy memory array 2 is arranged at only one location, for example, not only timing optimization will be disturbed, but also a process failure due to memory cell pattern imbalance or a place where there is no dummy memory array will be dead. It is also a means for solving the problem of area overhead due to space.

  Further, since the dummy memory cell is composed of one transistor and the source node of the transistor is connected to the power supply, it is not necessary to consider the defect of the dummy memory cell capacitor, and it is necessary for reading to the dummy memory cell. This is an effective means because it is not necessary to write data. Although the dummy memory cell is composed of one transistor, it is needless to say that it may be composed of two or more transistors.

  Further, as shown in FIG. 6, by providing the latch circuit 73 at the output of the logic circuit 7, even when the column switch connected to the dummy sense amplifier is turned off, the output data is output while the peripheral circuit read operation reference signal RE is H. This is an effective means.

  Next, a configuration in which two or more sense amplifiers are connected to the dummy data line by a switch will be described with reference to FIG. As shown in FIG. 7, two sense amplifiers DSA0 and DSA1 are connected to dummy data lines DDL / XDDL via N-channel transistors 20, 21; 22, 23 whose gates are controlled by a control signal DCS. ing. As a result, data can be read at twice the speed of the dummy data line DDL / XDDL of the dummy memory cell than the data line DL / XDL of the memory cell. When the potential difference necessary for amplifying XDL and the potential difference necessary for switching of the NOR circuit 71 of the data line sense amplifier control signal generation logic circuit 7 are 1: 2, the data line sense amplifier of the replica circuit is activated. This is an effective means because the signal generation timing and the amplification timing of the data line sense amplifier 61 can be made equivalent.

  Also, by configuring the sense amplifier column switch control signal and the dummy sense amplifier column switch control signal to be different, the dummy sense amplifier column switch can be controlled regardless of the column decode input. The sense amplifier can be connected to one dummy data line. Further, even if the number of dummy sense amplifiers changes, it is effective because it does not affect the drive timing and drive capability of the column switch of the sense amplifier.

  Next, a configuration in which the dummy data line is not a complementary line and the wiring adjacent to the dummy data line is a power supply line will be described with reference to FIG. As shown in FIG. 8, the dummy data line DDL is connected to the sense amplifiers DSA0 and DSA1 through N-channel transistors 20 and 21 whose gates are driven by column switch signals CS0 and CS1, respectively. The N channel transistors 22 and 23 connected to one of the sense amplifiers DSA0 and DSA1 have a gate that is a VSS power supply and a source that is open. With this configuration, since one of the complementary dummy data lines is the VSS power supply line, it can be used not only as a shield effect for the dummy data line read operation necessary for the replica circuit operation, but also the operation of the heavy dummy data line can be performed. The effect of reducing current consumption by using only one can be expected. Although the VSS power supply line is used, it goes without saying that the power supply line may be the VDD power supply line. In that case, there is a means of connecting to the source node of the N-channel transistor and connecting the gate node to the VSS power supply.

  In addition, it cannot be overemphasized that the further effect can be anticipated by combining each of the above forms.

<< Modification of First Embodiment >>
FIG. 9 is a block diagram showing a main configuration of the semiconductor memory device according to the modification of the first embodiment of the present invention. In particular, the data line sense amplifier control signal generation logic circuit 9 is different from the first embodiment, and a specific circuit diagram is as shown in FIG. In FIG. 10, 91 is a NOR circuit group, 92 is a dummy write buffer group, 93 is an OR circuit, and the logical sum of a plurality of dummy data lines DDL <0> to DDL <n> is a data line sense amplifier. 6 control signal DACNT.

  According to the modification, by taking a logical sum of a plurality of dummy data lines, even if there is a defect in one of the dummy memory cells, the data from the remaining dummy data lines is used as a data line sense amplifier control signal. Since it can be transferred to the generation logic circuit 9, it is an effective means for realizing the operation of a desired replica circuit. Usually, the number of dummy data lines can be determined by a trade-off between the occurrence rate of process defects and the overhead of circuit area. Needless to say, the data of two or more dummy data lines all have the same logical value.

  Needless to say, a further effect can be expected by combining the present embodiment and the first embodiment.

<< Second Embodiment >>
FIG. 11 is a block diagram showing a main configuration of the semiconductor memory device according to the second embodiment of the present invention. In FIG. 11, 10 and 11 are a memory array including a redundant word line RWL0, a dummy memory array, and 12 is a redundant decoding circuit capable of switching to a redundant word line when the memory array 10 and the dummy memory array 11 are defective. Is a row decoder.

  In the semiconductor memory device configured as described above, when a memory cell connected to WL0 of the memory array 10 is defective, for example, the address of the redundant word line is designated using a fuse function or the like, and the access is defective. When the word line WL0 is hit, the redundant decode circuit controls to switch access to the redundant word line RWL0, and transfers data from the redundant memory cell to the bit line BL. This makes it possible to repair defective cells.

  Similarly, even when a dummy memory cell connected to WL0 of the dummy memory array 11 has a defect, the redundancy decoding circuit can perform control to switch access to the redundant word line RWL0, so that the dummy memory array 11 can be relieved. Become.

  In this way, by applying redundant circuits such as redundant memory cells and redundant word lines, which have existed in the past, to the dummy memory array, it is possible to relieve the defects of the dummy memory array, so that the replica circuit can be stably realized. This is not only possible, but it is an effective means because the dead space in the dummy memory array by placing redundant memory cells can be used effectively.

  It goes without saying that a further effect can be expected by combining this embodiment with the first embodiment and the modification of the first embodiment.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described. The main configuration of the semiconductor memory device in the present embodiment is as shown in FIGS. 1 to 4, and the data write operation to the dummy memory array will be described with reference to the timing chart of FIG.

  First, when there is a write request to the memory, the control circuit 8 generates a write operation reference signal WEA and generates a peripheral circuit write operation reference signal WE. As a result, the data input signal DI is driven by the write buffer 6 and transfers data to the data lines DL / XDL. At the same time, the write buffer 72 of the data line sense amplifier control signal generation logic circuit 7 transfers the dummy data input signal DDI to the dummy data lines DDL / XDDL. The input address signal is transmitted to the row decoder 3 by the write operation reference signal WEA, and the selected word line WL0 is activated by the decode signal. Thereafter, data read from the memory cell connected to the selected word line WL0 and the dummy memory cell to the bit line BL / XBL and the dummy bit line DBL / XDBL is amplified by the sense amplifier activation signal SEN. Next, the column switch signal CS0 that drives the gate of the N-channel transistor that connects the data line and the sense amplifier and the dummy data line and the sense amplifier is activated, so that the data on the data line DL / XDL passes through the sense amplifier. It is written in the memory cell. Similarly, the data on the dummy data lines DDL / XDDL is also written into the dummy memory cell via the sense amplifier.

  Finally, the write operation reference signal WEA and the peripheral circuit write operation reference signal WE are set to the L level after a certain period, so that the internal circuit of the memory enters a standby state for the next operation.

  As described above, the data of the dummy bit line, the sense amplifier, and the dummy data line is provided from the dummy memory cell by providing the function of writing the desired data to the memory cell at the same time as the write request at the time of the write request. Can be set to a desired data value, which is an effective means. In addition, since initialization of dummy memory cells or writing of desired data is performed simultaneously with the writing of memory cells, this is an effective means for eliminating the overhead of circuit operation.

  Further, the input signal DDI of the write buffer 72 connected to the dummy bit lines DDL / XDDL is connected to the VDD power supply or the ground potential, so that a desired input can be made in accordance with the write request without adding a new input signal to the memory. Since fixed data can be written into a dummy memory cell connected to an address, it is effective in reducing the number of pins of the memory.

  Further, the logic value of the input signal DDI of the write buffer 72 connected to the dummy data line DDL / XDDL can be changed from the outside, and the output of the data line sense amplifier control signal generation logic circuit 7 even if the logic level of the input signal DDI is changed. Although not shown so that the logic level at the time of activation of the signal DACNT does not change, for example, by providing two signal paths different for one inverter stage by a selection circuit and switching according to the potential level of the input signal DDI By unifying the read operation of the dummy memory cell caused by process conditions, external conditions, etc. (for example, the L level is easier to read than the H level) to a data value that is easy to read, for example. The stable operation of the replica circuit including it can be realized.

  In addition, it has a function of activating a switch connecting the sense amplifier connected to all the word lines and all the dummy memory cells and the sense amplifier connected to all the dummy memory cells and the dummy data line. Can be written into the dummy memory cells all at once, so that the data can be efficiently executed, for example, during an initial sequence of the memory or in idle time such as a standby mode. In addition, by setting this function as a mode setting function, a normal write request to the memory can be performed by adding control for stopping the write buffer for writing to the dummy data line, for example, other than during the mode setting batch writing operation. Since the write operation to the dummy memory cell including the dummy data line is sometimes limited, the current consumption can be reduced. Further, since it is not necessary to perform the operation at the same time as the normal operation, a stable operation of the replica circuit operation can be realized by, for example, performing a write operation to the dummy memory cell with a sufficiently low operating frequency and a margin.

  It goes without saying that a further effect can be expected by combining this embodiment and each of the above embodiments.

<< Modification of Third Embodiment >>
FIG. 13 is a block diagram showing a main configuration of a semiconductor memory device according to a modification of the third embodiment of the present invention. A data write operation to the dummy memory array 102 attached to the memory array 101 of the semiconductor memory device configured as shown in FIG. 13 will be described.

  A flag INT that defines a data write operation to the dummy memory array 102 is activated in the mode register 111 by an external control signal CNT. As a result, the write buffer 110 is activated to transfer the dummy data input signal DDI to the dummy data line DDL. In the selection circuit 112, since the flag INT is H data, the input signal DCLK that repeats the H level and the L level at a constant cycle is selected, and the refresh counter 113 is counted up. The address signal selected by the count-up operation of the refresh counter 113 is decoded by the row decoder 103, and the operation of sequentially selecting all the word lines is performed as in the refresh operation. Similarly to this word line operation, the sense amplifier connected to the selected word line is also activated, and although not shown, the switch connecting the sense amplifier connected to the dummy memory array 102 and the dummy data line DDL is also connected to the selected sense amplifier. By activating only the switch, desired data can be written to the dummy memory array 102. By continuing this operation until the refresh counter 113 goes around, data writing to all the dummy memory arrays 102 can be completed.

  In response to a normal refresh request, the refresh counter 113 operates in response to the refresh command signal REF because the flag INT is inactive.

  As described above, using an existing memory circuit, an operation of passing a large current instantaneously as in a batch write operation to the dummy memory array 102 is not required, and the dummy memory array 102 has a timing different from that of the normal operation. Since initialization is possible and refresh operation of the memory array 101 and the dummy memory array 102 can be realized at the same time, an optimum circuit can be realized in terms of circuit operation, current consumption, and circuit area.

  As an example, the write operation to the dummy memory array 102 is defined by the mode setting using the mode register 111, but any circuit configuration that can realize the write operation to the dummy memory array 102 using the refresh counter 113 is possible. It goes without saying that such a circuit configuration may be used.

<< Fourth Embodiment >>
FIG. 14 is a block diagram showing a main configuration of a semiconductor memory device according to the fourth embodiment of the present invention. In FIG. 14, reference numeral 13 denotes an output selection circuit. The output signal PDO at the time of testing is a mode of the test output of the data output DO from the memory cell and the output signal DDO of the sense amplifier control signal generation logic circuit 7 for the data line. The circuit configuration is such that it can be switched and output by the selection signal MODE.

  A data read operation of the dummy memory cell of the semiconductor memory device configured as described above will be described.

  When the signal DACNT becomes H level in the replica circuit operation shown in FIG. 5, the other output signal DDO of the data line sense amplifier control signal generation logic circuit 7 also becomes H level as shown in FIG. At this time, if the mode selection signal MODE is at H level, H level data is output to the output signal PDO.

  When the mode selection signal MODE is at L level, the output signal DO from the memory cell is output as the test output signal PDO. Thus, ON / OFF of the external output of the output DDO of the data line sense amplifier control signal generation logic circuit 7 can be switched.

  As described above, since there is a means for outputting the data of the dummy memory cell to the outside by selecting the mode of the test result of the memory, the defect circuit of the replica circuit including the dummy memory cell can be inspected, so only the memory cell In addition, it is possible to carry out memory remedy treatment such as identification of a defective portion and redundancy remedy for a dummy memory cell.

  In the example, the output DDO of the data line sense amplifier control signal generation logic circuit 7 is output as it is through the selection signal. However, a circuit configuration in which a stable external output result is obtained by a configuration in which the output DDO is latched may be used. Needless to say.

  In addition, when there are a plurality of outputs DDO of the data line sense amplifier control signal generation logic circuit 7, by using a part or all of the data output path, a test output terminal which is normal at the time of testing is used, and a dummy memory is used. This is an effective means for reducing the number of memory terminals and the circuit area because data can be read from the dummy memory cell without the need to increase the number of output terminals specifically for cell data confirmation.

  Each of the data line and the dummy data line is provided with a precharge circuit so that the precharge potential of the data line is different from the precharge potential of the dummy data line. As an example, the precharge potential of the dummy data line is set to the VDD potential, the start timing of the read amplifier that amplifies the data line is generated using the switching characteristics of the transistor, and the precharge potential of the data line is set to 1/2 VDD potential. Since the power consumed by a large number of data lines in the memory can be suppressed to ½ compared to the VDD precharge potential, this is an effective means for reducing the power consumption of the memory.

  It goes without saying that a further effect can be expected by combining this embodiment and each of the above embodiments.

  The semiconductor memory device according to the present invention can realize a high-speed access time by logically determining the start timing of the sense amplifier that amplifies the data line that varies depending on the memory capacity and has the heaviest load on the data access time, In addition, it has an effect that various memory specifications can be easily realized, and is useful for a system LSI or the like in which a large number of memories and various types of specifications are mounted.

1 is a block diagram showing a main configuration of a semiconductor memory device according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating specific circuit configurations of a memory array, a dummy memory array, and a row decoder in FIG. 1. FIG. 2 is a circuit diagram showing a specific circuit configuration of a data line sense amplifier / write buffer in FIG. 1. FIG. 2 is a circuit diagram showing a specific circuit configuration of a data line sense amplifier control signal generation logic circuit in FIG. 1; 2 is a timing chart showing a data read operation of the semiconductor memory device of FIG. FIG. 5 is a circuit diagram showing a modification of the data line sense amplifier control signal generation logic circuit of FIG. 4. FIG. 5 is a block diagram illustrating a modification of the dummy memory array in FIG. 2. FIG. 10 is a block diagram showing another modification of the dummy memory array in FIG. 2. It is a block diagram which shows the main structures of the semiconductor memory device in the modification of the 1st Embodiment of this invention. FIG. 10 is a circuit diagram illustrating a specific circuit configuration of a data line sense amplifier control signal generation logic circuit in FIG. 9; FIG. 5 is a block diagram showing specific circuit configurations of a memory array, a dummy memory array, and a row decoder of a semiconductor memory device according to a second embodiment of the present invention. 12 is a timing chart illustrating a data write operation of the semiconductor memory device according to the third embodiment of the present invention. It is a block diagram which shows the main structures of the semiconductor memory device in the modification of the 3rd Embodiment of this invention. It is a block diagram which shows the main structures of the semiconductor memory device in the 4th Embodiment of this invention. It is a block diagram which shows the main structures of the conventional semiconductor memory device. 16 is a timing chart showing circuit operation of the semiconductor memory device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Memory array 2 Dummy memory array 3 Row decoder 4 Precharge circuit 5 Precharge circuit 6 Data line sense amplifier / write buffer 7 Data line sense amplifier control signal generation logic circuit 8 Control circuit 9 Data line sense amplifier control signal generation Logic circuit 2
DESCRIPTION OF SYMBOLS 10 Memory array containing redundant cell 11 Dummy memory array 12 containing redundant cell Row decoder 13 containing redundant decoding circuit Output selection circuit 20-23 N channel transistor 61 which comprises column switch 61 Data line sense amplifier 62 Write buffer 71 NOR circuit 72 Dummy write buffer 73 Latch circuit 91 NOR circuit group 92 Dummy write buffer group 93 OR circuit 101 Memory array 102 Dummy memory array 103 Row decoder 110 Dummy write buffer 111 Mode register 112 Select circuit 113 Refresh counter 201 Data Detection circuit 202 SA control generation circuit

Claims (26)

A memory cell;
A word line and a bit line connected to the memory cell;
A first sense amplifier connected to the bit line;
A dummy memory cell;
A dummy bit line connected to the dummy memory cell;
A second sense amplifier connected to the dummy bit line;
A data line connected to the first sense amplifier;
A third sense amplifier connected to the data line;
A dummy data line connected to the second sense amplifier;
A semiconductor memory device comprising a logic circuit connected to the dummy data line,
The logic circuit detects that the static data generated by the second sense amplifier that amplifies the dynamic data read to the dummy bit line exceeds the switching potential of the transistor at the potential on the dummy data line. The semiconductor memory device is characterized in that the output signal is an input signal for starting the third sense amplifier . The semiconductor memory device according to claim 1.
A semiconductor memory device comprising a latch circuit at the output of the logic circuit. The semiconductor memory device according to claim 1.
A semiconductor memory device comprising means for latching a signal of a dummy data line that is input to the logic circuit according to a logic value of an output signal of the logic circuit. The semiconductor memory device according to claim 1.
Each of the memory cell and the dummy memory cell is composed of one transistor and one capacitor. The semiconductor memory device according to claim 1.
A word line connected to the dummy memory cell and a word line connected to the memory cell are the same wiring. The semiconductor memory device according to claim 1.
The semiconductor memory device, wherein the bit line and the dummy bit line are arranged in parallel with the data line and the dummy data line. The semiconductor memory device according to claim 1.
A semiconductor memory device, wherein the dummy memory cell is disposed adjacent to a row decoder including a word driver, and has a delay circuit for adjusting an output timing of the logic circuit. The semiconductor memory device according to claim 1.
A semiconductor memory device, wherein adjacent capacitors of the dummy memory cell are joined. The semiconductor memory device according to claim 1 or 5 ,
A dummy memory array including the dummy memory cell, the dummy bit line, and the second sense amplifier is disposed for each memory array including the memory cell, the word line, the bit line, and the first sense amplifier. A semiconductor memory device. The semiconductor memory device according to claim 1.
The dummy memory cell is composed of one transistor, and the source node of the transistor is connected to a power source. The semiconductor memory device according to claim 1.
2. A semiconductor memory device according to claim 1, wherein two or more second sense amplifiers are connected to the dummy data line by a switch. The semiconductor memory device according to claim 11 .
2. A semiconductor memory device according to claim 1, wherein a control signal for a switch for connecting the data line and the first sense amplifier is different from a control signal for a switch for connecting the dummy data line and the second sense amplifier. The semiconductor memory device according to claim 1.
2. The semiconductor memory device according to claim 1, wherein the dummy data line is not a complementary line, and a wiring adjacent to the dummy data line is a power supply line. The semiconductor memory device according to claim 1.
2. The semiconductor memory device according to claim 1, wherein the logic circuit has a function of taking a logical sum of two or more dummy data lines. The semiconductor memory device according to claim 14 .
A semiconductor memory device characterized in that data of the two or more dummy data lines have the same logical value. The semiconductor memory device according to claim 1.
Redundant memory cells;
A redundant word line connected to the redundant memory cell;
A bit line connected to the redundant memory cell;
Redundant dummy memory cells;
A semiconductor memory device further comprising a dummy bit line connected to the redundant dummy memory cell. The semiconductor memory device according to claim 16 .
The logic circuit detects and outputs that the static data generated by the second sense amplifier that amplifies the dynamic data of the redundant dummy memory cell exceeds the switching potential of the transistor at the potential on the dummy data line. The semiconductor memory device is characterized in that the input signal is an input signal for starting the third sense amplifier. The semiconductor memory device according to any one of claims 1, 14 , and 16 ,
A write buffer connected to the data line;
A write buffer connected to the dummy data line;
A semiconductor memory device further comprising means for writing data into the dummy memory cell during a write operation to the memory cell. The semiconductor memory device according to claim 18 .
A semiconductor memory device, wherein an input of a write buffer connected to the dummy data line is connected to a power supply or a ground potential. The semiconductor memory device according to claim 18 .
A semiconductor memory device comprising a function capable of changing a logical value of input data of a write buffer connected to the dummy data line from the outside and not changing an output logic of the logic circuit. The semiconductor memory device according to claim 18 .
A semiconductor memory device, further comprising means for batch writing to all dummy memory cells. The semiconductor memory device according to claim 18 .
A refresh counter for controlling refresh;
Means for writing data into the dummy memory cell connected to the word line selected using the refresh counter. The semiconductor memory device according to any one of claims 1, 14 , and 16 ,
A semiconductor memory device further comprising means for reading the output of the logic circuit to the outside. 24. The semiconductor memory device according to claim 23 .
A semiconductor memory device having a function of switching ON / OFF of an external output of the logic circuit. 24. The semiconductor memory device according to claim 23 .
A semiconductor memory device characterized in that a part or all of the data output of the memory cell is used for an external output of the logic circuit. The semiconductor memory device according to any one of claims 1, 14 , and 16 ,
A precharge circuit for precharging the data line and the dummy data line,
A semiconductor memory device, wherein a precharge potential of the data line is different from a precharge potential of the dummy data line.

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