WO2005091301A1 - 強誘電体メモリ - Google Patents
強誘電体メモリ Download PDFInfo
- Publication number
- WO2005091301A1 WO2005091301A1 PCT/JP2004/004118 JP2004004118W WO2005091301A1 WO 2005091301 A1 WO2005091301 A1 WO 2005091301A1 JP 2004004118 W JP2004004118 W JP 2004004118W WO 2005091301 A1 WO2005091301 A1 WO 2005091301A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- ferroelectric
- voltage
- sense amplifier
- line
- ferroelectric memory
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
- G11C11/22—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using ferroelectric elements
Definitions
- the present invention relates to a ferroelectric memory having a ferroelectric capacitor.
- a ferroelectric memory operates by using a ferroelectric capacitor that uses a ferroelectric as an insulating material as a variable capacitor, and utilizes the fact that residual polarization remains even when the voltage applied to the ferroelectric capacitor is zero. Data can be retained even when power is not supplied. By arranging ferroelectric memory cells in an array utilizing this non-volatility, a non-volatile memory can be realized.
- ferroelectric capacitors ferroelectric material mainly composed of PZT (lead zirconate titanate) or ferroelectric material with bismuth layered perovskite structure such as SBT (bismuth tantalum strontium) Charges are available.
- Patent Document (1) Japanese Unexamined Patent Application Publication No. 2000-19089
- An object of the present invention is to eliminate the limitation on the number of times of reading of a ferroelectric memory. Another object of the present invention is to reduce power consumption during a read operation of a ferroelectric memory.
- the pair of ferroelectric capacitors of the memory cell are set to have polarization vectors opposite to each other in order to hold complementary logical values.
- One end and the other end of the ferroelectric capacitor are connected to one bit line pair and one plate line, respectively.
- the voltage setting circuit sets the voltage difference between both ends of the ferroelectric capacitor lower than the coercive voltage in order to charge the ferroelectric capacitor in the read operation.
- the differential sense amplifier amplifies the voltage difference on the bit line generated according to the difference in the amount of charge to the ferroelectric capacitor in order to read the logical value held in the memory cell.
- the inversion of the polarization vector of the ferroelectric capacitor is prevented.
- the polarization vector is not inverted, the data held in the memory cells will not be destroyed even if the power is cut off during the read operation. That is, non-volatility can be maintained.
- the area of the hysteresis loop which is the locus of the change in the dielectric polarization value of the ferroelectric capacitor, can be reduced, so that the power consumption during the read operation can be reduced.
- the pair of transistors of the level converter have a gate connected to a bit line, a source, one of drains connected to a power supply line, and a source connected to a power supply line.
- the other of the drains is connected to the differential input of the differential sense amplifier. Therefore, the voltages of the bit line pairs are respectively amplified by the level converter and then further amplified by the differential sense amplifier. Therefore, even when the voltage difference between the pair of bit lines is small, the differential sense amplifier can reliably perform the amplification operation and read the data held in the memory cell. Wear.
- bit line pair Since the bit line pair is connected to the differential sense amplifier via the level converter, the bit line pair is not directly affected by the operation of the differential sense amplifier. For this reason, it can be prevented that the voltage of the bit line pair fluctuates due to the operation of the differential sense amplifier, and that erroneous data is read. Also, it is possible to prevent an unintended voltage from being applied to the ferroelectric capacitor.
- the ferroelectric memory has the above-mentioned memory cell, a pair of bit lines, a plate line, and a level converter. Therefore, even when the voltage difference between the bit line pair is small, the differential sense amplifier can reliably perform the amplification operation and read data. Since the bit line pair is not directly affected by the operation of the differential sense amplifier, it is possible to prevent the voltage of the bit line pair from fluctuating due to the operation of the differential sense amplifier, thereby preventing erroneous data from being read.
- the memory cell has a transfer gate connecting one end of each ferroelectric capacitor to a bit line.
- the precharge circuit temporarily connects each bit line to a voltage line of a predetermined voltage before a transfer gate is turned on in a read operation. Therefore, the bit line pair is charged to a predetermined voltage before data is read from the memory cell, and thereafter, is held in a floating state. Therefore, in the read operation, the voltage of each bit line can be accurately changed according to the capacitance value of each ferroelectric capacitor, and the data held in the memory cell can be reliably read.
- the precharge circuit has a power switch, a ground switch, and an equalize switch.
- the power switch and the ground switch are temporarily turned on to connect a pair of bit lines to the power line and the ground line, respectively.
- the equalizing switch connects across a pair of bit lines after the power switch and the ground switch are turned off. Therefore, the precharge voltage can be easily generated using the bit line pair without forming a complicated circuit for generating the precharge voltage in the ferroelectric memory.
- the pair of transistors constituting the level converter are pMOS transistors.
- the bit line precharge voltage is preferably low in order to reduce power consumption.
- the transistor of the level converter is preferably formed of a pMOS transistor in order to increase the gate-source voltage during the read operation and operate at high speed. In other words, the read operation can be performed at high speed by configuring the transistor with a MOS transistor.
- the anti-leak switch is used in a read operation to provide a source (or drain) of a pair of transistors of a level converter in a read operation.
- the restore switch connects the differential output of the differential sense amplifier to the bit line, respectively. Connecting. For this reason, the differential sense amplifier does not need to drive the bit line for a while after the start of the amplification operation. Therefore, the amplification operation can be performed at high speed, and the read access time can be reduced. If the access time does not need to be reduced, the layout size of the differential sense amplifier can be reduced.
- the restore switch is turned on after the voltage corresponding to the read data is sufficiently generated by the differential sense amplifier.
- the differential output of the differential sense amplifier is connected to a bit line, and a memory cell restore operation is performed. By the restore operation, the remanent polarization value of the ferroelectric capacitor returns to the original value. That is, it is possible to prevent the data held in the memory cell from being destroyed.
- the presense amplifier has a gate and a drain connected to one and the other of the bit lines, respectively, and a source connected to a predetermined voltage line. With PMOS transistor connected Yes.
- Each restore switch has an nMOS transistor having one and the other of a source and a drain connected to a bit line and a differential output of a differential sense amplifier, respectively.
- the wrist switch is composed of nMOS transistors, the high-level voltage (for example, power supply voltage) amplified by the differential sense amplifier is reduced by the threshold voltage of the nMOS transistor and transmitted to the bit line. .
- the voltage of the bit line is set to a high level voltage without decreasing by the presence amplifier. As a result, the restore operation can be executed reliably.
- FIG. 1 is a block diagram showing a first embodiment of the ferroelectric memory of the present invention.
- FIG. 2 is a circuit diagram showing details of the memory core shown in FIG.
- FIG. 3 is a waveform diagram showing a read operation of the ferroelectric memory according to the first embodiment.
- FIG. 4 is a circuit diagram showing details of a memory core in a second embodiment of the ferroelectric memory of the present invention.
- FIG. 5 is a circuit diagram showing details of a memory core in a third embodiment of the ferroelectric memory of the present invention.
- FIG. 6 is a waveform diagram showing a read operation of the ferroelectric memory according to the third embodiment.
- FIG. 7 is a circuit diagram showing details of a memory core in a fourth embodiment of the ferroelectric memory of the present invention.
- FIG. 8 is a waveform diagram showing a read operation of the ferroelectric memory according to the fourth embodiment.
- Double circles in the figure indicate external terminals.
- the signal lines indicated by bold lines are composed of a plurality of lines.
- a part of the block to which the bold line is connected is composed of a plurality of circuits.
- signals supplied via external terminals use the same symbols as the terminal names. Also, the same symbol as the signal name is used for the signal line through which the signal is transmitted.
- FIG. 1 shows a first embodiment of the ferroelectric memory of the present invention.
- the ferroelectric memory is formed on a silicon substrate using a CMOS process.
- Ferroelectric The body memory is incorporated, for example, as a memory core in a system LSI mounted on a mobile phone.
- the ferroelectric memory includes a command buffer 10, a command decoder 12, a address decoder 14, a row decoder 16, a column decoder 18, an operation control circuit 20, a booster circuit 22, a word driver 24, a plate driver 26, and a memory core CORE. , A column control circuit 28 and a data input / output circuit 30.
- the command buffer 10 receives a command signal CMD such as a chip select signal, an output enable signal, and a write enable signal via a command terminal CMD, and outputs it to the command decoder 12.
- the command decoder 12 decodes the command signal CMD and outputs a result of the decoding to the operation control circuit 20.
- the types of commands include a read command, a write command, and a standby command indicating that these commands have not been input.
- the chip enable signal when the chip enable signal is active and the write enable signal is inactive, a read command is recognized. When the chip enable signal and the light enable signal are active, a write command is recognized. When the chip enable signal, write enable signal and output enable signal are inactive, the standby command is recognized.
- the address buffer 14 receives the address signal AD via the address terminal AD, and outputs upper bits and lower bits of the received address signal AD as an address signal RAD and a column address signal CAD, respectively.
- the mouth decoder 16 decodes the row address signal RAD to generate a decode signal RDEC, and outputs it to the word driver 24 and the plate driver 26.
- the column decoder 18 decodes the column address signal CAD, generates a decode signal CDEC, and outputs the signal to the column control circuit 28.
- the operation control circuit 20 includes a word driver 24, a plate driver 26, a column control circuit 28, and a data input / output circuit for executing a read operation and a write operation on the memory core CORE in accordance with the output of the command decoder 12.
- a control signal for controlling the operation of the circuit 30 is generated. Read operation and write operation are executed The period during which there is no data is a standby period.
- the operation control circuit 20 maintains the control signal at a predetermined level during the standby period.
- the booster circuit 22 generates a boosted voltage VPP (for example, 2.5 V) used for the high-level voltage of the word line WL using a power supply voltage VDD (for example, 2 V) supplied via a power supply terminal. .
- VPP boosted voltage
- VDD power supply voltage
- the word driver 24 selects a word line WL corresponding to the decode signal RDEC in response to a control signal from the operation control circuit 20 during a read operation and a write operation.
- the selected word line WL is set to the boost voltage VPP, and the unselected word lines WL are set to the ground voltage VSS.
- the word driver 24 maintains all the word lines WL at a low level (VSS) during the standby period, during the nonvolatile write operation, and during the recall operation.
- VSS low level
- the plate driver 26 selects a plate line PL corresponding to the decode signal RDEC in response to a control signal from the operation control circuit 20 during a read operation and a write operation.
- the selected plate line PL changes from a low level (VSS) to a high level (VDD) for a predetermined period.
- the plate driver 26 maintains all the plate lines PL at a low level (VSS) during the standby period.
- the memory core CORE includes a memory cell array ARY having a plurality of memory cells MC and bit line pairs BL and BLX arranged in an array, and a level compensator connected to each bit line pair L and BLX. It has an LC and a differential sense amplifier SA connected to the output of the level converter LC. Details of the memory core CORE are explained in Figure 2.
- the column control circuit 28 has a column switch that connects the low-power data bus lines LDB and LDBX corresponding to the decode signal C DEC to the global data bus line GDB in response to a control signal from the operation control circuit 20. ing.
- Data input / output circuit Reference numeral 30 outputs write data from the outside to the column control circuit 28 in response to a control signal from the operation control circuit 20, or outputs read data from the column control circuit 28 to the data terminal I / O.
- the number of data terminals I / O is, for example, 16 bits.
- FIG. 2 shows details of the memory core CORE shown in FIG.
- Each memory cell MC of the memory array ARY includes a pair of transfer transistors Nl and N2 (transfer gates) and a pair of ferroelectric capacitors FC1 and FC2 in order to hold one bit of information.
- One ends of the ferroelectric capacitors FC1 and FC2 are connected to complementary bit line pairs BL (BL1, BL2, ...) and BLX (BL1X, BL1) via transfer transistors N1 and N2, respectively.
- BL 2 X, The other ends of the ferroelectric capacitors FC1 and FC2 are connected to a common plate line PL.
- the gates of the transfer transistors Nl and N2 are connected to a common word line WL (WL1, WL2, ).
- the plate line PL is wired in common for a plurality of memory cells MC connected to a predetermined number of word lines WL.
- the level converter LC has a pair of pMOS transistors P 1 and P 2 whose gates are connected to the bit lines BL and B LX, respectively, and an nMO S transistor N 3 that connects the sources of the pMOS transistors P 1 and P 2 to the power supply line VDD. (Leak prevention switch). : The drains of the MOS transistors P1 and P2 are connected via complementary local data bus lines LDB (LDB1, LDB2, etc And LDBX (LDBIX, LDB2X,). Connected to input / output node of differential sense amplifier SA. The gate of the nMOS transistor N3 receives the enable signal LCEZ.
- the sense amplifier SA is composed of a pair of CMOS inverters whose inputs and outputs are connected to each other.
- the inputs and outputs of the CMOS inverter are connected to local data bus lines LDB and LDB X, respectively.
- the source of the pMOS transistor of the CMOS inverter receives the sense amplifier activation signal SAE, and the source of the nMOS transistor of the CMOS inverter receives the sense amplifier activation signal SA ⁇ X.
- the memory core CORE is a pMOS transistor P 3 (restore switch), It has a precharge circuit PRE and a bit line reset circuit BRS.
- One of the source and the drain of the pMOS transistor P3 is connected to the bit line BL (or B LX) and the local data bus line LD B (or LDBX), and the gate receives the restore signal RS TRX at the gate.
- the restore switch P3 has a function of changing the connection state between the bit lines BL and BLX and the differential sense amplifier SA from a disconnected state to a connected state during a read operation.
- the wrist switch P3 may be composed of an nMOS transistor.
- the gate voltage for turning on the nMOS transistor is set to the boosted voltage VPP or the power supply voltage VDD + ⁇ boosted by the bootstrap using the gate capacitance coupling.
- the precharge circuit PR # has an nMOS transistor connecting the bit lines BL and BLX to the precharge voltage line VPR, respectively, and an nMOS transistor connecting the bit lines BL and BLX to each other.
- Each nMOS transistor receives the precharge signal PREZ at the gate.
- the voltage of the precharge voltage line V? 1? 1 is set to a value lower than the coercive voltage of the ferroelectric capacitors FC 1 and FC 2 to prevent polarization reversal during the read operation.
- the precharge circuit PRE operates as a voltage setting circuit that sets a voltage difference between both ends of each of the ferroelectric capacitors FC1 and FC2 lower than the coercive voltage. With this setting, it is possible to prevent a voltage higher than the coercive voltage from being applied to both ends of each of the ferroelectric capacitors FC1 and FC2 during the read operation excluding the restore operation.
- the coercive voltage is 0.8 to 1.0 V when the ferroelectric material is PZT, and 0.5 to 0.9 V when the ferroelectric material is SBT.
- the voltage of the bit line before the word line WL is selected is VB L If the voltage applied to the dielectric capacitor is VFE, the voltage is VFE-0.8 XVB L. For this reason, for example, when the ferroelectric material is PZT, setting the precharge voltage VPR (bit line voltage) to 1.0 to 1.2 V reduces the voltage applied across the ferroelectric capacitor. It can be set below the coercive voltage.
- the bit line reset circuit BRS has the same circuit configuration as the precharge circuit PRE, and although not shown, the bit lines BL and BLX are connected to the ground line VSS. It has nMOS transistors connected to each other, and one MOS transistor connecting bit lines BL and BLX to each other. Each nMOS transistor receives a bit line reset signal RSTZ at its gate.
- the memory core CORE has the same circuit configuration as the bit line reset circuit BRS, and also has a data bus line reset circuit for connecting the local data bus lines LDB and LDBX to the ground line VSS. ing.
- the control signals PREZ, RSTZ, RSTRX, LCEZ, SAE, SAEX supplied to the memory core CORE and the data bus line reset signal supplied to the data path line reset circuit (not shown) are shown in Figure 1. It is generated by the operation control circuit 20 shown.
- FIG. 3 shows a read operation of the ferroelectric memory according to the first embodiment.
- logic 1 is previously written in the memory cell MC, and the ferroelectric capacitors FC1 and FC2 have different polarization vectors from each other.
- the ferroelectric capacitor FC 1 in which logic 1 is stored is The ferroelectric capacitor FC2 having a negative remanent polarization value and storing a logic 0 has a positive remanent polarization value.
- bit lines BL and BLX are set to the precharge voltage VPR by the bit line reset circuit BRS, and the low data bus lines LDB and LDBX are set by the data bus line reset circuit (not shown). After being reset to the ground voltage VSS, the floating state is maintained (Fig. 3 (a, b)).
- the operation control circuit 20 deactivates the precharge signal PREZ (FIG. 3 (c)). Due to this deactivation, the bit lines BL and BLX enter a floating state while being precharged to the precharge voltage VPR.
- the word driver 24 selects the word line WL according to the row address signal RAD, and changes the selected word line WL to the boost voltage VPP (FIG. 3 (d)). Due to this change, the transfer transistors N1 and N2 of the memory cell MC are turned on, and one ends of the ferroelectric capacitors FC1 and FC2 are connected to the bit lines BL and BLX.
- the ferroelectric capacitor A precharge voltage VPR is temporarily applied between both ends of the capacitors FC1 and FC2 (FIG. 3 (e)). Therefore, the dielectric polarization values of the ferroelectric capacitors FC 1 and FC 2 are as shown in “State 2”.
- the voltage V of the hysteresis loop shown in the figure indicates the voltage of the plate line PL based on the voltages of the bit lines BL and BLX. Therefore, on the hysteresis loop, both ends of the ferroelectric capacitors FC 1 and FC 2 receive the voltage “one VPR”.
- the precharge voltage VPR is lower than the coercive voltage, the polarization states of the ferroelectric capacitors FC1 and FC2 are not reversed by the application of the precharge voltage VPR.
- the ferroelectric capacitors F C1 and FC 2 have different polarization vectors, and their capacitance values are different from each other. For this reason, the voltages of the bit lines BL and BLX are different from each other (FIG. 3 (f)).
- the capacitance value of the ferroelectric capacitor FC 1 (stored logic 1) connected to the bit line BL is the capacitance value of the ferroelectric capacitor FC 2 (stored logic 0) connected to the bit line BLX. If greater, bit line BL has a lower voltage than bit line BLX.
- the enable signal LCEZ is activated (FIG. 3 (g)), and the sources of the pMOS transistors P1 and P2 of the level comparator LC are connected to the power supply line VDD (2 V), and the amplifier is used as an amplifier.
- the precharge voltage VPR is set to about 1.0 to 1.2 V as described above.
- the voltage of the bit lines BL and BLX is about 0.2 V lower than the precharge voltage VPR, and the gate-source voltage of the pMOS transistors P1 and P2 is -1.8 to 1. It becomes about 3V. Therefore, it can be operated at a higher speed than when the level converter LC is configured with nMOS transistors. Since high-speed operation is possible, the MOS size can be reduced. As a result, the disadvantage of the late size of the pMOS transistor with respect to the nMOS transistor is eliminated.
- the voltage of the local data bus lines LDB and LDBX rises according to the voltage of the bit lines BL and BLX (Fig. 3 (h)).
- the enable signal LCEZ is deactivated (Fig. 3 (i)). Note that the enable signal LCEZ is generated using a timing signal for generating the sense amplifier activation signals SAE and SAEX in order to deactivate the differential sense amplifier SA immediately before starting the operation.
- the sense amplifier activation signals SAE and SAEX are activated, and the differential sense amplifier SA starts operating (FIG. 3 (j)).
- the sense amplifier activation signal S AEX is not shown because it is an inverted signal of the sense amplifier activation signal SAE. Due to the amplification operation of the differential sense amplifier SA, the voltages of the local data bus lines LDB and LDB X change to the power supply voltage VDD and the ground voltage V SS, respectively (FIG. 3 (k)). Then, the column control circuit 28 and the data input / output circuit 3 • shown in FIG. 1 operate, and read data is output via the data terminal IZO.
- the reset switch P3 is off and the bit lines BL and B LX are Not connected to dynamic sense amplifier SA. Therefore, it is possible to prevent the voltages of the bit lines BL and BLX from being affected by noise due to the operation of the differential sense amplifier SA and from being affected by voltage changes of the local data bus lines LDB and LDBX. As a result, the polarization states of the ferroelectric capacitors FC1 and FC2 can be prevented from being affected by the noise of the differential sense amplifier SA and the voltage change of the local data bus lines LDB and LDBX. Due to the operation of the differential sense amplifier SA, it is possible to prevent the generation of coupling noise on the bit lines BL (BLX) adjacent to each other.
- the differential sense amplifier SA By turning off the wrist switch P3, the differential sense amplifier SA There is no need to charge and discharge the transmission lines BL and BLX. Therefore, the sensing speed of the read data can be increased, and the read access time can be reduced. In other words, the drive capability of the differential sense amplifier SA can be reduced, and its layout size can be reduced.
- the restorer signal RSTRX is activated (FIG. 3 (1)).
- the activation of the restore signal RSTRX connects the bit lines BL and BLX to the local data bus lines LDB and LDBX, respectively. Therefore, the voltages of the bit lines BL and BLX change to high level and low level, respectively (Fig. 3 (m)). Since the voltage of the plate line PL is the ground voltage V SS, one VDD is applied to both ends of the ferroelectric capacitor F C1 connected to the bit line BL (“state 3”). That is, the logic 1 is restored to the ferroelectric capacitor FC 1 storing the logic 1. On the other hand, in “state 3”, the voltage difference between both ends of the ferroelectric capacitor F C2 connected to the bit line B LX is 0 V.
- the plate line PL is activated for a predetermined period, and the restore operation of the ferroelectric capacitor FC2 storing logic 0 is performed (FIG. 3 (n)).
- the restorer operation of the ferroelectric capacitor FC 2 is performed by applying the power supply voltage VDD and the ground voltage VSS to both ends of the ferroelectric capacitor FC 2 connected to the bit line B LX. ("State 4").
- the voltage difference between both ends of the ferroelectric capacitor F C1 connected to the bit line BL is OV. Since the plate line PL needs to be changed only at the time of restoration, the number of times of driving the plate line PL is reduced, and power consumption is reduced.
- the sense amplifier activation signals S AE and S AEX are deactivated, and the differential sense amplifier SA stops operating (FIG. 3 (o)).
- the word line WL is deactivated (FIG. 3 (p)), and the connection between the bit lines BL, BLX and the ferroelectric capacitors FC1, FC2 is released.
- the bit line reset signal RSTZ and the data bus line reset signal are activated (FIG. 3 (q)), and the bit lines BL, BLX and the local data bus lines LDB, LDBX are connected to the ground voltage. It is reset to VSS (Fig. 3 (r, s)).
- the store signal R STRX is deactivated (FIG. 3 (t)), and the read operation is completed.
- a voltage higher than the coercive voltage is not applied to both ends of each of the ferroelectric capacitors FC1 and FC2. Therefore, the polarization vector does not reverse during the read operation. Therefore, it is possible to prevent the ferroelectric materials of the ferroelectric capacitors FC1 and FC2 from deteriorating.
- the area of the curve (closed loop) showing the change in the dielectric polarization value in the PV characteristic diagram is proportional to the power consumption. In the present embodiment, since the dielectric polarization values of the ferroelectric capacitors FC1 and FC2 do not greatly change during the read operation, the area of the closed loop is small, and the power consumption during the read operation is small.
- the polarization vectors of the ferroelectric capacitors F C1 and F C2 are always opposite to each other during the read operation. For this reason, even if the supply of the power supply voltage VDD to the ferroelectric memory is stopped due to some trouble during the read operation, the data stored in the memory cell MC can be prevented from being lost. More specifically, by reading the data of all the memory cells MC after the power is turned on again, the remanent polarization values of the ferroelectric capacitors F C1 and F C 2 can be restored.
- the polarization vectors of the ferroelectric capacitors FC 1 and FC 2 can be prevented from being inverted during the read operation, so that the ferroelectric material can be prevented from deteriorating.
- the limitation on the number of times of reading can be eliminated. Since the polarization vector is not inverted, it is possible to prevent the data held in the memory cell MC from being destroyed even when the power is cut off during the read operation.
- the area of the hysteresis loop which is the locus of the change in the dielectric polarization value of the ferroelectric capacitors F C1 and F C2, can be reduced, so that the power consumption during the read operation can be reduced.
- the differential sense amplifier SA After amplifying the voltages of the bit lines BL and BLX by the level converter LC and further amplifying them by the differential sense amplifier SA, even if the voltage difference between the bit line pair BL and BLX is small, the differential sense amplifier The SA can be reliably amplified, and the data held in the memory cell MC can be correctly read.
- each bit line BL, BLX By temporarily connecting each bit line BL, BLX to the pre-charge voltage line VPR before turning on N1, N2, the voltage of each bit line BL, BLX is connected to each ferroelectric capacitor FC. 1. The value can be accurately changed according to the capacitance value of FC2, and the data held in the memory cell MC can be reliably read.
- the level converter LC By configuring the level converter LC with the pMOS transistors P1 and P2, the voltages of the bit lines BL and BLX lower than the coercive voltage can be reliably amplified, and the amplification speed can be improved. As a result, the read access time can be reduced.
- the nMOS transistor N 3 leakage prevention switch
- the differential sense amplifier SA drives the bit lines BL and BLX for a while after the amplification operation starts. No need. Therefore, the amplification operation can be performed at high speed, and the read access time can be reduced. If it is not necessary to reduce the access time, the layout size of the differential sense amplifier S A can be reduced.
- the wrist switch P3 can prevent the bit lines BL and BLX from being directly affected by the operation of the differential sense amplifier SA. That is, it is possible to prevent the voltages of the bit lines B L and B LX from fluctuating due to the operation of the differential sense amplifier S A, thereby preventing erroneous data from being read.
- the restore operation can be reliably performed, so that the data held in the memory cell MC can be prevented from being broken.
- FIG. 4 shows details of the memory core in the second embodiment of the ferroelectric memory of the present invention. Circuits and signals that are the same as the circuits and signals described in the first embodiment are given the same reference numerals, and detailed descriptions thereof are omitted.
- a level converter LC is different from the first embodiment.
- Other configurations are the same as those of the first embodiment (FIG. 1). That is, the ferroelectric memory is formed on a silicon substrate by using a CMOS process, and is incorporated as a memory core in a system LSI mounted on a mobile phone, for example.
- the level converter LC has gates connected to bit lines B LX and BL, respectively. And a pair of nMOS transistors N4 and N5, and an nMOS transistor N3 (leakage prevention switch) that connects the drains of the nMOS transistors N4 and N5 to the power supply line VDD.
- the sources of the nMOS transistors N 4 and N 5 are connected to the data bus lines LDB (LDB 1, LDB 2,...) and LD BX (LDB IX, LDB 2 X,. Connected to the input / output node of the differential sense amplifier SA via
- FIG. 5 shows details of the memory core in the third embodiment of the ferroelectric memory of the present invention. Circuits and signals identical to the circuits and signals described in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.
- the wrist switch is configured by an nMOS transistor N6 instead of the pMOS transistor P3 of the first embodiment.
- the gate of the nMOS transistor N6 receives the restore signal RESRZ.
- the memory core CORE has a new pre-sense amplifier PSA.
- Other configurations are the same as those of the first embodiment (FIG. 1) and the second embodiment (FIG. 4). That is, a ferroelectric memory is formed on a silicon substrate using a CMOS process, and is incorporated as a memory core in a system LSI mounted on a mobile phone, for example.
- the pre-sense amplifier PSA is composed of a pair of pMOS transistors whose gates are connected to bit lines BLX (BL1X, BL2X, ...) and BL (BL1, BL2, ...), respectively.
- pMO S transistor ⁇ 4 The drain of P5 is connected to bit lines BL and BLX, respectively.
- the gate of the pMOS transistor P6 receives the pre-sense signal PS AEX.
- FIG. 6 shows a read operation of the ferroelectric memory according to the third embodiment. Detailed description of the same operations as in FIG. 3 described above is omitted.
- the pre-sense signal PSAEX is activated after the restore signal RSTRZ is activated and before the plate line PL changes to a high level.
- the deactivation timing of the pre-sense signal P S AEX is the same as the restore signal R STRZ.
- the activation level (high level voltage) of the restore signal R STRZ is the power supply voltage VDD (2 V).
- Other operations are the same as in FIG.
- the pMOS transistors P4 and P5 of the presense amplifier PSA are activated in response to the activation of the presense signal PSAEX (FIG. 6 (a)).
- the pMOS transistor P4 turns on in response to the change in the bit line BLX corresponding to the local data bus line LDBX changed to the low level voltage VSS to the low level voltage VSS.
- the voltage of the bit line BL is surely increased to the power supply voltage VDD (FIG. 6 (b)). For this reason, the restore operation of the ferroelectric capacitors FC1 and FC2 is ensured without using the boosted voltage VPP for the high-level voltage of the restorer signal RSTRZ supplied to the gate of the restore switch N6. Be executed.
- the same effects as in the first embodiment can be obtained.
- the pre-sense amplifier PSA is connected to the bit lines BL and B LX so that the high-level voltage VDD output by the differential sense amplifier SA is applied.
- the restore operation can be executed reliably. Since the boosted voltage VPP does not need to be used for the high level voltage of the restorer signal RSTRZ, the drive capability of the booster circuit 22 (FIG. 1) can be reduced, and the layout size can be reduced.
- FIG. 7 shows details of the memory core in the fourth embodiment of the ferroelectric memory of the present invention. Circuits and signals that are the same as the circuits and signals described in the first embodiment are given the same reference numerals, and detailed descriptions thereof are omitted.
- a precharge circuit PRE is different from the first embodiment. Other configurations are the same as those of the first embodiment. That is, a ferroelectric memory is formed on a silicon substrate using a CMOS process, and is incorporated as a memory core in a system LSI mounted on a mobile phone, for example.
- the precharge circuit PRE has an nMOS transistor N 7 (equalize) having a gate connected to the precharge signal line PRE 2 Z, and one of the source and drain connected to the bit lines BL and BLX, respectively. Switch), the gate is connected to the precharge signal line PRE 1 Z, the source is connected to the bit line BL, the drain is connected to the power supply voltage line VDD, and the nMOS transistor N 8 (power switch) is connected to the gate. Is connected to the precharge signal line PRE 1 Z, the source is connected to the ground line VSS, and the drain is connected to the bit line BLX.
- the transistor has an nMOS transistor N 9 (ground switch).
- FIG. 8 shows a read operation of the ferroelectric memory according to the fourth embodiment. Detailed description of the same operations as in FIG. 3 described above is omitted.
- This embodiment has a feature in the precharge operation of the bit lines BL and BLX before the start of the read operation.
- the precharge signal PRE1Z is activated for a predetermined period (FIG. 8 (a)), and the bit lines BL and BLX are set to the high level voltage (VDD—the threshold voltage of the nMOS transistor N8) and Change to the ground voltage VSS. That is, the bit line BL is charged according to the high level voltage (FIG. 8B).
- the precharge signal PRE2Z is activated for a predetermined period (FIG. 8 (c)).
- the bit lines BL and BLX are equalized and set to the desired precharge voltage VPR (1Z2 of the bit line BL voltage) (Fig. 8 (d) ). That is, the precharge voltage VPR is easily generated by a simple circuit using the charge charged on the bit line BL.
- the precharge voltage VPR can be easily generated by using the charge charged in the bit line BL.
- the plate line PL is provided for each of the predetermined number of memory cells MC.
- the present invention is not limited to such an embodiment.
- a plate line PL may be wired in common to all the memory cells MC.
- the number of times the plate line PL is driven during the read operation is small, so that the ferroelectric capacitor of the memory cell MC in which the read operation is not performed can be reduced from being deteriorated by the back switching due to the drive of the plate line PL. .
- precharge circuit PRE applied to the above-described fourth embodiment may be applied to the first to third embodiments.
- the present invention is not limited to such an embodiment.
- the present invention may be applied to a ferroelectric memory mounted on an IC card.
- the word driver 24 instead of the booster circuit 22, the time from power-on to the start of access can be reduced.
- ferroelectric memory of the present invention it is possible to prevent the ferroelectric material from being deteriorated by the read operation, and to eliminate the limitation on the number of times of reading of the ferroelectric memory.
Landscapes
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Dram (AREA)
- Semiconductor Memories (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2004/004118 WO2005091301A1 (ja) | 2004-03-24 | 2004-03-24 | 強誘電体メモリ |
JP2006511115A JP4477629B2 (ja) | 2004-03-24 | 2004-03-24 | 強誘電体メモリ |
US11/442,343 US7139187B2 (en) | 2004-03-24 | 2006-05-30 | Ferroelectric memory |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/JP2004/004118 WO2005091301A1 (ja) | 2004-03-24 | 2004-03-24 | 強誘電体メモリ |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/442,343 Continuation US7139187B2 (en) | 2004-03-24 | 2006-05-30 | Ferroelectric memory |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2005091301A1 true WO2005091301A1 (ja) | 2005-09-29 |
Family
ID=34993949
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2004/004118 WO2005091301A1 (ja) | 2004-03-24 | 2004-03-24 | 強誘電体メモリ |
Country Status (3)
Country | Link |
---|---|
US (1) | US7139187B2 (ja) |
JP (1) | JP4477629B2 (ja) |
WO (1) | WO2005091301A1 (ja) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
TWI283872B (en) * | 2005-04-06 | 2007-07-11 | Winbond Electronics Corp | Equalizer and method thereof and memory device |
JP2006344289A (ja) * | 2005-06-08 | 2006-12-21 | Toshiba Corp | 強誘電体記憶装置 |
JP5264611B2 (ja) * | 2009-04-28 | 2013-08-14 | パナソニック株式会社 | 半導体記憶装置 |
US8189415B2 (en) * | 2009-10-05 | 2012-05-29 | Nanya Technology Corp. | Sensing amplifier applied to at least a memory cell, memory device, and enhancement method for boosting the sensing amplifier thereof |
US10109350B2 (en) * | 2016-07-29 | 2018-10-23 | AP Memory Corp., USA | Ferroelectric memory device |
US9858979B1 (en) | 2016-10-05 | 2018-01-02 | Micron Technology, Inc. | Reprogrammable non-volatile ferroelectric latch for use with a memory controller |
TWI693766B (zh) * | 2018-04-18 | 2020-05-11 | 力旺電子股份有限公司 | 靜電放電防護裝置 |
US10964372B2 (en) * | 2019-06-14 | 2021-03-30 | Micron Technology, Inc. | Memory cell biasing techniques |
CN113689904A (zh) | 2020-07-03 | 2021-11-23 | 长江存储科技有限责任公司 | 用于对三维FeRAM中的存储单元进行读取和写入的方法 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01192078A (ja) * | 1988-01-28 | 1989-08-02 | Hitachi Ltd | 半導体記憶装置及びレベルシフト回路 |
JP2000100176A (ja) * | 1998-09-28 | 2000-04-07 | Hitachi Ltd | 強誘電体メモリ |
JP2000187990A (ja) * | 1998-12-24 | 2000-07-04 | Nec Corp | センスアンプ回路及びそれを用いた記憶装置並びにそれに用いる読出し方法 |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR0141494B1 (ko) * | 1988-01-28 | 1998-07-15 | 미다 가쓰시게 | 레벨시프트회로를 사용한 고속센스 방식의 반도체장치 |
JP3191549B2 (ja) * | 1994-02-15 | 2001-07-23 | 松下電器産業株式会社 | 半導体メモリ装置 |
TW378323B (en) * | 1994-09-22 | 2000-01-01 | Matsushita Electric Ind Co Ltd | Ferroelectric memory device |
EP0757354B1 (en) * | 1995-08-02 | 2002-05-22 | Matsushita Electric Industrial Co., Ltd | Ferroelectric memory device |
JPH10270654A (ja) * | 1997-03-27 | 1998-10-09 | Toshiba Corp | 半導体記憶装置 |
-
2004
- 2004-03-24 JP JP2006511115A patent/JP4477629B2/ja not_active Expired - Fee Related
- 2004-03-24 WO PCT/JP2004/004118 patent/WO2005091301A1/ja active Application Filing
-
2006
- 2006-05-30 US US11/442,343 patent/US7139187B2/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01192078A (ja) * | 1988-01-28 | 1989-08-02 | Hitachi Ltd | 半導体記憶装置及びレベルシフト回路 |
JP2000100176A (ja) * | 1998-09-28 | 2000-04-07 | Hitachi Ltd | 強誘電体メモリ |
JP2000187990A (ja) * | 1998-12-24 | 2000-07-04 | Nec Corp | センスアンプ回路及びそれを用いた記憶装置並びにそれに用いる読出し方法 |
Also Published As
Publication number | Publication date |
---|---|
US20060215438A1 (en) | 2006-09-28 |
JP4477629B2 (ja) | 2010-06-09 |
US7139187B2 (en) | 2006-11-21 |
JPWO2005091301A1 (ja) | 2008-02-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7042784B2 (en) | Nonvolatile ferroelectric memory device with split word lines | |
JP3916837B2 (ja) | 強誘電体メモリ | |
US7447058B2 (en) | Write margin of SRAM cells improved by controlling power supply voltages to the inverters via corresponding bit lines | |
US7486571B2 (en) | Semiconductor memory device | |
KR100276569B1 (ko) | 강유전메모리장치 | |
US10332571B2 (en) | Memory device including memory cell for generating reference voltage | |
US7280384B2 (en) | Semiconductor memory device | |
US7139187B2 (en) | Ferroelectric memory | |
US7133306B2 (en) | Semiconductor memory device for securely retaining data | |
JP2000339973A (ja) | 強誘電体メモリおよび半導体メモリ | |
JP3226433B2 (ja) | 強誘電体メモリ装置 | |
US6924999B2 (en) | Ferroelectric memory | |
US6208550B1 (en) | Ferroelectric memory device and method for operating thereof | |
JP4996177B2 (ja) | 半導体記憶装置、およびデータ読み出し方法 | |
JP2004055007A (ja) | 強誘電体記憶装置及びその読み出し方法 | |
JP4083173B2 (ja) | 半導体メモリ | |
US6898107B2 (en) | Nonvolatile FeRAM control device | |
JP4983062B2 (ja) | メモリ装置 | |
US7193888B2 (en) | Nonvolatile memory circuit based on change in MIS transistor characteristics | |
JP2004319047A (ja) | 強誘電体メモリ | |
JP2001202778A (ja) | 半導体記憶装置 | |
JP2007157328A (ja) | 強誘電体メモリ装置 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NA NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): BW GH GM KE LS MW MZ SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LU MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application | ||
WWE | Wipo information: entry into national phase |
Ref document number: 2006511115 Country of ref document: JP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 11442343 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWW | Wipo information: withdrawn in national office |
Country of ref document: DE |
|
WWP | Wipo information: published in national office |
Ref document number: 11442343 Country of ref document: US |
|
122 | Ep: pct application non-entry in european phase |