WO2005050663A1 - 半導体集積回路装置 - Google Patents
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- WO2005050663A1 WO2005050663A1 PCT/JP2003/014901 JP0314901W WO2005050663A1 WO 2005050663 A1 WO2005050663 A1 WO 2005050663A1 JP 0314901 W JP0314901 W JP 0314901W WO 2005050663 A1 WO2005050663 A1 WO 2005050663A1
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C15/00—Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores
- G11C15/04—Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores using semiconductor elements
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C15/00—Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores
- G11C15/04—Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores using semiconductor elements
- G11C15/043—Digital stores in which information comprising one or more characteristic parts is written into the store and in which information is read-out by searching for one or more of these characteristic parts, i.e. associative or content-addressed stores using semiconductor elements using capacitive charge storage elements
Definitions
- the present invention relates to a semiconductor integrated circuit device including a content “addressable” memory cell (CAM cell) for comparing information stored in a storage node with input information, and in particular, to refresh ternary information.
- CAM cell content “addressable” memory cell
- This technology relates to a technology that integrates ternary dynamic CAM cells (TDCAM cells) that store data at high density, and is effective when applied to technology that realizes low-power and high-speed TDCAM arrays.
- the TDCAM cell configuration in the ternary dynamic content addressable memory is, for example, 'Rec 0 rdsofthe 2 00 00 age (s): 10 1-1 0 5 '(hereinafter referred to as reference 1).
- FIG. 21 shows an example of the cell configuration shown in FIG.
- This senor is formed by a mixed DRAM (DynamicRanDomAcAcssMemory) processing technique, and the NMOS (N channel Met a1
- the transistor T1, T2 and the capacitors C1, C2 have a memory function of storing ternary information.
- VP LT is a so-called plate electrode voltage input to one electrode of the capacitors C 1 and C 2.
- ⁇ Value information is information '1', information '0', information 'X' indicating a so-called 'D on' tcare 'state. If the high voltage is logic '1' and the low voltage is logic '0', the logic value of the storage node (N l, N 2) is (1, 0) for information '1' and information '0' in the case of (0, 1) and (0, 0) for information 'X'.
- the refresh of the stored information is performed via the transistors T 1 and T 2, and although omitted in the figure, reading and rewriting are performed using the sense amplifiers connected to the bit lines BL 1 and BL 2, respectively. Is performed.
- the information to be compared with the stored information in the search operation is ternary information input via the search lines SL1, SL2.
- the details are information '1' and information '0', and information 'X' indicating a so-called 'MASK' state.
- the connection between the match line ML precharged to a high voltage and the discharge line DCL fixed to a low voltage (for example, the ground voltage VSS) is cut off (cut-off). ), The match line is held at the precharge voltage.
- the match line ML and the discharge line DC L are cut off, so the same as in the case of the match ,
- the match line is held at the precharge voltage.
- the current path is formed by conduction of either the stacked transistors T3 and T4 or the transistors # 5 and # 6.
- the line ML and the discharge line DCL are short-circuited, and the match line ML is discharged toward the ground voltage VSS.
- the comparison result is determined by discriminating the voltage change of the match line ML due to the above operation with a match line sense amplifier (not shown).
- Figure 26 is a truth table summarizing the above search operations.
- FIG. 22 shows a main part of the cell configuration and the array configuration of FIG. In this figure, the same symbols are assigned to transistors that have the same role as in Figure 21 to aid understanding.
- This cell compares the information held in the storage circuits CST 1 and CST 2 with the information input via the search lines SL 1 and SL 2 by a comparison circuit CCP. It has two features. The first feature is that a signal corresponding to a comparison result is generated by a charge sharing operation using a match line ML and a common source line CSL arranged in parallel.
- the second feature is that the connection of the transistors constituting the comparison circuit C CP differs from the cell of FIG. That is, the transistor T4 connected to the storage node N1 is connected to the match line ML, and the transistor T3 connected to the search line SL2 is connected to the common source line CSL.
- the transistor T6 connected to the storage node N2 is connected to the matching line ML, and the transistor T5 connected to the search line SL1 is connected to the common source line CSL.
- the comparison circuit CCP can perform the same XNOR operation as the cell in FIG. 21 even if the connection inside the cell is different.
- the PMOS line (P-channel MOS) transistor THP and the NMOS transistor TL are turned on to precharge the match line ML to the high voltage VP CH and the common source line CSL to the ground voltage VSS. I do.
- the precharge enable signals P CHB and P CH are driven to turn off the transistors THP and TL, respectively, and the match line ML and the common source line CSL are set to the floating state. .
- comparison information is input via the search lines SL1 and SL2.
- the connection between the match line ML and the common source line CSL is cut off, so that the match line ML is kept at the precharge voltage VPCH.
- the comparison result of the information is determined by discriminating the voltage change of the match line ML.
- the voltage of the match line ML after the short circuit will be equal to the intermediate voltage VP CH / 2 between the precharge voltage VP CH and the ground voltage VSS.
- the common source line CSL is connected as in the configuration of Fig. 21. Since the voltage amplitude of the match line is smaller than when connected to the ground voltage VSS, the power required for the match line precharge is suppressed.
- the CAM described in the above-mentioned literature is a device that compares a plurality of pieces of stored information (hereinafter, referred to as entries) and comparison information (hereinafter, referred to as search keys) at the same time and determines these similarities. is there.
- the memory cell shown in FIG. 21 has a large number of elements and signals, so that it is difficult to realize a regular memory array layout and structure such as a general-purpose DRAM, and it is difficult to introduce a self-alignment process. There is fear.
- FIG. 23 shows a main part of the cell configuration and array configuration of the CAM, which has been studied in detail prior to the present application with respect to this problem.
- This figure is an equivalent circuit model of the memory cell CMC shown in FIG. 22 that takes into account the coupling capacitance.
- the coupling capacitances CSC 1 and CSC 2 and the storage node N are connected between the search lines SL 1 and SL 2 and the common source line CSL.
- coupling capacitance C NM C 1, C between l, N 2 and matching wire ML NMC 2 is inserted.
- FIGS. 24 and 25 show an example of the search operation timing in the configuration of FIG. Here, it is assumed that the memory cell CMC holds the storage information “1” using the storage circuits CST 1 and CST2.
- the reference voltage VR is a reference voltage for discriminating the match line voltage.
- VSIG is a voltage difference between the match line voltage required for accurate discrimination and the reference voltage VR, and is hereinafter referred to as a comparison signal voltage.
- the transistors THP and TN are turned on, and the match line ML Are driven to the precharge voltage VP CH and the common source line CSL to the ground voltage VSS.
- the precharge enable signal PREB having the ground voltage VSS is driven to the power supply voltage VDD
- the precharge enable signal PRE having the power supply voltage VDD is driven to the ground voltage VSS.
- each of the transistors THP TL is turned off, and the matching line ML and the common source line CSL are set in a floating state.
- a search key is input via the search line.
- the search key information to be compared with the storage information of the memory cell CMC is “1”
- the search line SL1 is driven by the power supply voltage VDD, and the search line SL2 is held at the ground voltage VSS.
- the search line SL1 is coupled to the common source line CSL via the parasitic capacitance CSC1, the voltage of the common source line CSL increases in accordance with the activation of the search line SL1.
- the voltage rise due to the fluctuation of the search line voltage is described below. I will call it sound.
- the actual search key is information composed of a plurality of bits
- a plurality of memory cells are connected to one match line, and a plurality of The search line drive noise is superimposed by driving the scan lines simultaneously.
- the magnitude of the search line drive noise VNC shown in FIG. 24 is a value corresponding to the data pattern of the search key, that is, the number of drive lines of the search line.
- the match line ML is coupled to the storage nodes N 1 and N 2 via the coupling capacitors CNMC 1 and CNMC 2, respectively. However, since the voltages of these storage nodes are held, the precharge voltage VP Retained in CH.
- the transistor T5 of the memory cell CMC11 is turned on, but since the transistor T6 is in the power-off state, the current flows to the storage node N2 side of the comparison circuit CP. Does not flow.
- the comparison circuit CP of the memory cell CMC 11 is in a matching state.
- the match line ML is kept at the precharge voltage VP CH, the match is detected by detecting in some way that the positive comparison signal VSIG is generated on the match line ML with respect to the reference voltage VR. Is determined.
- search line SL1 is held at the ground voltage VSS, whereas the search line SL1 is held at the ground voltage VSS.
- Search line SL2 is driven to power supply voltage VDD.
- the search line SL2 is coupled to the common source line CSL via the parasitic capacitance CSC2, the common source line CSL is activated in response to the activation of the search line SL2 as in FIG. CSL voltage rises.
- the match line ML driven by the precharge voltage VP CH is discharged toward the intermediate voltage VM, and the common source line CSL that has been precharged to the ground voltage VSS is charged toward the intermediate voltage VM. .
- the comparison result is determined to be inconsistent by discriminating in some way that the voltage of the match line ML has fallen below the reference voltage VR and a negative comparison signal voltage VSIG has been generated with respect to the reference voltage. I do.
- the search line SL2 which is at the power supply voltage VDD, is driven to the ground voltage VSS
- the precharge enable signal PREB which is at the power supply voltage VDD, is at the ground voltage VSS
- the precharge enable signal is at the ground voltage VSS.
- the search operation is completed by precharging L and the common source line C SL respectively.
- t1 is the time from when the search line is driven to when the negative comparison signal voltage 1 V SIG is generated, and is hereinafter referred to as a comparison time.
- FIG. 7 shows a match line waveform in a case where other memory cells connected to the match line ML are in a match state, in order to explain the operation timing under the worst condition.
- the voltage after the short circuit will be VPCHZ2.
- the voltage VM becomes higher than VPCH / 2 depending on the magnitude of the search line driving noise.
- the transistor T3, ⁇ 5 in the memory cell CMC shown in FIG. Voltage becomes smaller, and Since the threshold voltage rises due to the bias effect, the driving capability decreases.
- the precharge power of the match line is suppressed, but the comparison time t1 is significantly increased by the data pattern of the search key, and the search operation may be delayed.
- An object of the present invention is to provide a memory cell layout and an internal node connection technique to which a general-purpose DRAM processing technique is applied for higher integration of a TDCAM cell.
- Another object of the present invention is to provide a technique for avoiding an increase in comparison time due to search line driving noise in a charge sharing method effective for reducing the power of a match line.
- the present invention provides a plurality of match line pairs, a plurality of search line pairs crossing the plurality of match line pairs, and a plurality of match line pairs arranged at intersections of the plurality of match line pairs and the plurality of search line pairs.
- a plurality of match line pairs, each of the plurality of match line pairs includes a precharge circuit, and the plurality of precharge circuits includes a first match line among the match line pairs.
- the plurality of memory cells have a storage circuit and a comparison circuit, and the comparison circuit
- One of the electrodes is Of the loam line is to be connected, respectively.
- the present invention provides a plurality of match line pairs, a plurality of search line pairs intersecting the plurality of match line pairs, and a plurality of match line pairs arranged at intersections of the plurality of match line pairs and the plurality of search line pairs.
- each of the plurality of memory cells has a storage circuit and a comparison circuit, and the comparison circuit
- the first and second MOS transistors are connected in series to form a first current path between the pair of match lines, and the third and second MOS transistors are connected in series to form a second current path.
- a fourth MO transistor The gate electrodes of the first and third MOS transistors are connected to a plurality of search lines, respectively, and are connected to the source or drain of the first and third MOS transistors. Either electrode is self-aligning
- the gates of the second and fourth MOS transistors are connected to the storage circuit, respectively, and connected to the plurality of first match lines by the contacts formed by the integration process. Either the source or drain electrode of the fourth MOS transistor is connected to a plurality of second matching lines by a contact formed by a self-aligned process.
- the present invention relates to a plurality of first match lines, a plurality of search line pairs crossing the plurality of first match lines, and a plurality of bit line pairs parallel to the plurality of search line pairs.
- a semiconductor integrated circuit device having a plurality of memory cells arranged at intersections of a plurality of first match lines and a plurality of search line pairs, wherein each of the plurality of memory cells includes a storage circuit and A comparison circuit, wherein the storage circuit is connected to a plurality of bit line pairs; the comparison circuit is connected to a plurality of search line pairs and a plurality of first match lines; The voltage amplitude of the line pair is larger than that of the multiple search line pairs.
- FIG. 1 is a diagram showing another example of a configuration of a memory array using a memory cell including six transistors and two capacitors according to the first embodiment of the present invention.
- FIG. 2 is a diagram showing the memory array in FIG.
- FIG. 3 is a diagram showing a layout of a layer below the third metal layer of the memory array in FIG. 1
- FIG. 4 is a diagram showing a layout of a layer below the third metal layer of the memory array in FIG.
- FIG. 5 is a cross-sectional view showing a structure along a line AA ′ shown in the figure.
- FIG. 5 is a cross-sectional view showing a structure along a line BB ′ shown in the layout diagram of FIG. , FIG.
- FIG. 6 is a cross-sectional view showing a structure taken along the line C-C ′ shown in the layout diagram of FIG. 3, and FIG. 7 is a view taken along the line D—D ′ shown in the layout diagram of FIG.
- FIG. 8 is a cross-sectional view showing the structure of the portion along the line
- FIG. 8 is a diagram showing an example of a simplified equivalent circuit considering the parasitic capacitance in the memory cell of FIG. 1
- FIG. 9 is a diagram of FIG.
- FIG. 10 is a diagram schematically showing the parasitic capacitance shown in the array
- FIG. 10 is a diagram showing an example of a simplified equivalent circuit in consideration of the parasitic capacitance in the memory array of FIG. 1
- FIG. 11 is a memory array of FIG. FIG.
- FIG. 12 is a diagram showing an example of a search operation timing when a match entry is detected in FIG. 1.
- FIG. 12 is a diagram showing an example of a search operation timing when a mismatch entry is detected in the memory array of FIG. 3 shows six transistors and two capacitors according to the first embodiment of the present invention.
- FIG. 14 is a diagram showing another configuration example of a memory array using memory cells composed of capacitors.
- FIG. 14 is a diagram showing an example of a simplified equivalent circuit in the memory array of FIG. 13 in consideration of parasitic capacitance. Is a diagram showing an example of a search operation timing when a match entry is detected in the memory array of FIG. 14, and
- FIG. 16 is an example of a search operation timing when a mismatch entry is detected in the memory array of FIG. FIG.
- FIG. 17 is a diagram showing another configuration example of a memory array using a memory cell composed of six transistors and two capacitors according to the second embodiment of the present invention.
- FIG. 19 is a block diagram showing an example of a power supply voltage supplied to each circuit block in the memory array according to the third embodiment of the present invention.
- FIG. 19 is a diagram showing a specific example of an element circuit in the read / write circuit block of FIG. Fig. 20 shows an example of the configuration.
- Fig. 20 shows an example of the refresh operation timing in the memory array of Fig. 18.
- Fig. 21 shows a ternary dynamic circuit composed of six transistors and two capacitors.
- Fig. 22 shows a conventional example of a memory cell.
- Fig. 22 shows a conventional example of a memory cell and a memory array.
- Fig. 22 shows a conventional example of a content-addressable memory cell and a memory array using a comparison signal voltage generation method using a charge sharing operation.
- Fig. 2 shows an example of an equivalent circuit in the memory cell of Fig. 22 considering the coupling capacitance between wires.
- Fig. 24 shows the search operation timing when a match entry is detected in the memory cell of Fig. 23.
- FIG. 25 shows an example of a search operation timing when a mismatched entry is detected in the memory cell of FIG. 23, and
- FIG. 26 shows an example of a search operation timing in FIG. 21.
- Kicking is an explanatory diagram showing a truth table of the search operation of the memory cell.
- each block of the embodiment is not particularly limited, typically, a single crystal silicon is formed by a known semiconductor integrated circuit technology such as a CMOS (complementary MOS transistor) or a three-dimensional capacitor. It is formed on such a number of semiconductor substrates.
- CMOS complementary MOS transistor
- FIG. 1 shows a configuration example of a memory array.
- This configuration has the following two features.
- the second feature is that the search line and the match line driven by high voltage are coupled by a parasitic capacitance described later.
- the comparison signal voltage is generated on the two match lines by the charge sharing operation, and the signal generated on the high voltage side match line is discriminated by the match determination circuit.
- the two corresponding match lines will be referred to as a match line pair if necessary.
- One ⁇ 3 memory cells have a corresponding Are connected to each other.
- two corresponding bit lines such as a bit line BL 11 and a bit line BL 21 will be referred to as a bit line pair as necessary.
- two corresponding search lines such as the search line SL11 and the search line SL21 will be referred to as a search line pair as necessary.
- the two matching lines such as the matching lines HML 1 and LML 1, are hereinafter referred to as a matching line pair as necessary.
- the memory cell has a TD CAM cell configuration consisting of two capacitors and six transistors, as in FIG. However, the difference is that the sources of the transistors T4 and T6 connected to the discharge line DCL in FIG. 21 are connected to the low-voltage side match line LML.
- the elements constituting the memory cell MC are divided into two circuits for each function for comparison with the configuration of the memory cell CMC shown in FIG.
- the transistor T l, ⁇ 2 and the capacitor C l, j 2 are composed of three memory circuits (, transistor (first transistor) T 3, transistor (third transistor) ⁇ 4, transistor (second transistor) ⁇ 5, and the transistor (fourth transistor) ⁇ 6 constitute the comparison circuit C ⁇ ⁇ ⁇ ⁇ .
- the connection order of the transistors is reversed with respect to the precharge voltage of the match line, and from the ⁇ voltage match line HML to the low voltage match line LML.
- One is connected to transistors # 3 and # 5, and the other is connected to transistors # 4 and # 6 in that order.
- the oral decoder XDEC and the read / write circuit block RWB are circuit blocks used for reading or writing of stored information (here, entry) or for refreshing.
- the sense amplifier has, for example, a well-known cross-coupled latch configuration, which discriminates and amplifies a signal read to a bit line, and furthermore, applies a bit, a current and a storage node to a voltage corresponding to write information. Drive.
- the transistor THN connects the power supply terminal of the precharge voltage VH to the high voltage side match line, and the transistor TL connects the power supply terminal of the precharge voltage VL to the low voltage side match line LML. And connect.
- the first effect is a reduction in power consumption.
- a search key is input via a search line pair to generate a signal corresponding to a result of information comparison. It occurs on the high voltage side match line due to the charge sharing operation. Therefore, the voltage amplitude of the high-voltage side match line can be suppressed to about half the precharge voltage difference of the match line pair, so that the power required for the precharge operation of the match line can be reduced. .
- Second is the suppression of the comparison signal generation time.
- the transistors T 3, T 4, T 5, and T 6 in the memory cell can avoid a decrease in drive capability due to a decrease in the gate-source voltage or an increase in the threshold voltage due to the substrate Pierce effect. Can be shortened. With the above two effects, it is possible to realize a TCAM that performs a search operation at low power and at high speed.
- the first feature lies in the arrangement of the gate electrodes.
- the gate electrode of the transistor connected to the storage node is L-shaped, and the polysilicon layer is arranged at a minimum interval along with the lead line.
- the second feature is that the diffusion region of the transistor and the gate electrode at the storage node are connected via a first metal layer corresponding to a wiring layer used for forming a general-purpose DRAM bit line.
- the third feature is that the memory cell is connected to the bit line, search line, and match line. The purpose is to share contacts and through holes with adjacent memory cells.
- the fourth feature is that the electrodes of the four transistors constituting the comparison circuit are arranged in parallel.
- FIG. 2 shows the layout of a layer below the second metal layer for a portion of the memory array.
- the rectangle MCA drawn with a thick dotted line indicates an area of one memory cell, and is not an actual layout pattern.
- each side of the square M CA is arranged line-symmetrically.
- the memory cell has an active region pattern FL, a polysilicon pattern Ps, which is a gate electrode lead line of a transistor formed on a silicon substrate, and a capacitor z.
- Plate metal layer pattern PLT forming the upper electrode of the capacitor
- first metal layer pattern FM used for connection between elements inside the memory cell and connection between contact and through hole described later
- high voltage side match line and low The second metal layer pattern SM that forms the voltage side match line, the first contact pattern FC that connects the active region to the first metal layer, and the second contact pattern that connects the polysilicon layer and the first metal layer It is composed of SC, a third contact pattern TC connecting the activation region and the lower electrode of the capacitor, a first through hole pattern FT connecting the first metal layer and the second metal layer, and the like.
- the corresponding node name is shown in parentheses after the pattern name, and the memory cells are arranged at the intersections of the match lines HML2, LML2 and the search lines SL12, SL22.
- the area surrounded by the square MCA is the memory cell MC22 in the second row and second column in the memory array of FIG.
- FIG. 3 is a layout diagram in which a pattern of a layer above the second metal layer is added to FIG. 2.
- a third metal layer pattern TM forms a bit line ⁇ search line. Varnish
- the through hole pattern ST connects the second metal layer and the third metal layer.
- bit lines are formed using the first metal layer FM. However, because of the large number of wires in the memory cell shown in the figure, it is further raised to the upper third metal layer TM.
- FIG. 4 is a diagram schematically showing a cross section AA ′ shown in FIG. 2 in the storage circuit STC.
- an insulator 101 for element isolation is embedded in a P-type semiconductor substrate 100, and an N-type diffusion layer region 102 in an active region pattern FL is formed.
- a gate cap 106 made of an insulating film is formed on the gate electrode simultaneously with the side wall.
- the first metal layer 200 connects the elements inside the memory cell, and the second metal layer 201 is used for connecting the first through hole and the second through hole.
- the lower contact 300 is formed of polysilicon at the first contact connecting the N-type diffusion layer region and the first metal layer
- the upper contact 301 is formed of the first metal at the first contact. It is formed of the same material as the layer.
- the third contact 302 is formed of the same material as the first metal layer so as to connect the gate electrode and the first metal layer.
- the first through hole 400 The first metal layer and the second metal layer are connected.
- the node name is shown in parentheses after the layer name, corresponding to FIG.
- the node name indicated by the gate electrode 104 in FIG. 4 one of the source or drain electrode of the transistor T1 and the gate electrode of the transistor T4 are connected to the first metal layer 200. It can be easily understood that they are connected by the first and second contacts.
- connection portion of the internal node is omitted in FIG. 4, but is also used in a circuit block arranged outside the memory array.
- the source of the transistor that drives the lead is used in the general-purpose DRAM decoder XDEC.
- the connection between the N-type diffusion layer of either the source or the drain and the lead line formed of polysilicon is made using a similar structure.
- FIG. 5 is a diagram schematically showing the cross section BB ′ shown in FIG. 2 in the storage circuit STC.
- the upper contact 303 is formed of polysilicon in a third contact connecting the N-type diffusion layer region 102 and the lower electrode of the capacitor.
- a lower electrode 600 of the capacitor is formed of polysilicon, and an upper electrode 602, that is, a plate electrode is formed on the surface of the lower electrode 600 via an insulating film 61 of the capacitor.
- the node name is shown in parentheses after the layer name, corresponding to Fig. 2.
- the gate electrodes of the transistor T1 and the transistor T4 are arranged in parallel by the node name indicated by the gate electrode 104.
- the lower contact of the third contact has the same structure as the lower contact 300 of the first contact, and is a so-called self-aligned contact formed simultaneously so as to fill the gap between the side walls 105. (SAC). This processing technique is called a self-alignment process widely used in general-purpose DRAM.
- the first metal layer 200, the upper contact 301 of the first contact, and the second contact 302 prevent deterioration of electrical characteristics due to heat treatment when forming a capacitor in these upper layers.
- it is formed of tungsten having a high melting point.
- FIG. 6 is a diagram schematically showing the cross section CC ′ shown in FIG. 3 in the comparison circuit CP.
- the bit line / search line is formed of the third metal layer 20.
- the node name is shown in parentheses after the layer name in correspondence with FIG. 4.
- the node name shown by the gate electrode 104 in FIG. It can be easily understood that the gate electrodes of the stars T3, T4, T5 and T6 are arranged in parallel with each other.
- the lower contact 300 of the first contact is formed by the above-described self-alignment process. These contacts are shared between adjacent transistors.
- FIG. 7 is a diagram schematically showing a cross section taken along the line DD ′ shown in FIG. 3 in the comparison circuit CP.
- the second through hole 401 connects the second metal layer and the third metal layer.
- Transistors T3, T5 and search line pair SL12, SL22 are connected using Nikon contact 302, first through hole 400, and second through hole 401, respectively. I have.
- the first effect is that by using a self-aligning process similar to general purpose DRAM,? The point is that it is possible to reduce the alignment margin as considered in the Konkan D RAM.
- the second effect is that, by using the first and second contacts and the first metal layer, the same processing steps as those of the circuit block arranged outside the memory array of the desk-top DRAM can be applied to the internal node of the memory cell. The point is that connection can be realized.
- the third effect is that the cell area can be suppressed by sharing a connection portion between a bit line pair, a search line pair, and a match line pair with a memory cell with an adjacent memory cell.
- the fourth effect is that the connection portion between the low-voltage side match line and the memory cell is shared with the adjacent memory cell, and the match line pair is arranged using the same second metal layer, so that the side wall insulating film can be formed.
- the load capacitance of the match line pair can be made almost the same while the parasitic capacitance generated on the low voltage side match line is made the same as that of the high voltage side match line.
- This fourth effect is suitable for a charge shearing operation in which the amplitude of the matching wire pair is halved in a search operation to be described later while a sufficiently large comparison signal voltage is applied. that's all As a result, a memory cell capable of performing the charge sharing operation can be realized with a small area.
- the memory cell area is calculated, as an example, assuming that the following four rules are applied.
- the first rule is that the minimum value of the wiring width and spacing of each layer is F (F is the minimum processing dimension).
- the second rule is that the pattern of each contact and each through hole is a square with F on one side.
- the third rule is that the margin for each contact is zero.
- the fourth rule is that the margin between each through hole and each metal layer is F / 4 only on two sides.
- the transistors T3, T4, T5, and T6 in the comparison circuit can be arranged at the minimum interval, so that the cell width is 8F.
- the word lines WL can be arranged at a pitch of 10.25 F, a memory cell of 82 times the square of F can be realized.
- FIG. 8 shows a simplified equivalent circuit model of the memory cell MC22 in the memory array of FIG.
- the capacitances C SH1 and C SH2 are parasitic capacitances generated between the search lines SL 12 and SL 22 and the high-voltage side match line H ML 2, respectively. Further, the capacitances C SL 1 and C SL 2 are parasitic capacitances respectively generated between the search lines SL 12 and SL 22 and the low voltage side matching line LML 2.
- the capacitances CNH 1 and CNH 2 are between the storage nodes N 1 and N 2 and the high-voltage match line H ML 2
- the capacitances CNL 1 and CNL 2 are between the storage nodes N 1 and N 2 and the low-voltage match line LML
- FIG. 9 schematically shows the positions where the parasitic capacitances are generated by writing these parasitic capacitances on the layout diagram shown in FIG.
- the parasitic capacitances CSH1 and CSH2 are connected to the search lines SL12 and SL22 at the lower contact 300 of the first contact, as shown in Fig. 6. This is caused by passing very close between the polysilicon layers 104 forming the connected gate electrodes.
- the thickness of the side wall insulating film 105 is about 30 nm when the minimum processing dimension is 0.13 ⁇ .
- the thickness of the interlayer insulating film 500 between the second metal layer 201 forming the high voltage side match line HML2 and the third metal layer 202 forming the search lines SL12 and SL22 The thickness is several hundred nm. Therefore, the size of the parasitic capacitances C SH1 and C SH2 is almost determined by the shape of the portion where the gate electrode and the first contact sandwich the third wall insulating film 105.
- the low-voltage side match line LML1 is connected to the storage nodes N 1 and N 2 at the lower contact 300 of the first contact. This occurs because they pass very close to the polysilicon layer 104 forming the gate electrode of No. 6 respectively. Since the structures are similar, the sizes of the parasitic capacitances CSH1 and CSH2 and the sizes of the parasitic capacitances CNL1 and CNL2 are almost equal.
- the parasitic capacitances CNH 1 and CNH 2 are formed between the polysilicon layer 104 forming the gate electrodes of the transistors T 4 and T 6 and the second metal layer 201 forming the high-voltage side match line HML 2. It is generated by the insulating film 500, respectively.
- the thickness of the interlayer insulating film in this portion is almost equal to the height of the capacitor shown in FIG. 5, and is about 1 m. Therefore, the magnitude of the parasitic capacitances CNH 1 and CNH 2 is extremely small as compared with the parasitic capacitances CNL 1 and CNL 2.
- the parasitic capacitances CSL1 and CSL2 are determined by the low voltage side match line LML2 based on the layout shown in Fig. 9 and the positional relationship between the search lines SL12 and SL22 in Fig. 6 and the high voltage side match line HML2. It can be easily understood that it is generated by the interlayer insulating film 500 between the second metal layer 201 to be formed and the third metal layer 202 to form the search lines SL12 and SL22. Therefore, the magnitudes of the parasitic capacitances CSL1, CSL2 are extremely small as compared with the parasitic capacitances CSH1, CSH2.
- FIG. 10 shows the configuration of the memory array according to FIG. 1 using the simplified equivalent circuit model of FIG.
- the precharge enable signal PCL is driven to the boosted voltage VDH to activate the transistors THN and TL in the precharge circuit PCH1, thereby precharging the high-voltage side match line HML1.
- the charge voltage VH and the low-voltage side match line LML1 are driven to the precharge voltage VL, respectively.
- the figure shows an example of operation timing when the precharge voltage VH is the power supply voltage VDD and the precharge voltage VL is the ground voltage VSS.
- the boost voltage VDH is set to a voltage higher than the power supply voltage VDD so that the transistor THN sufficiently conducts.
- VDH threshold voltage of the transistor THN
- VDH> VH + VTN there is a relation of VDH> VDD + VTN.
- the transistors THN and TL in the precharge circuit P CH 1 are turned off by driving the precharge enable signal PC, which is the boosted voltage VDH, to the ground voltage VSS.
- Matching line HML 1, L ML 1 is set to the floating state.
- a search key is input via the search line pair.
- the search key information to be compared with the storage information of the memory cell MC 11 is “1”
- the search line SL 11 which is at the voltage VSS, is driven by the power supply voltage VDD, and the search line SL 21 is held at the ground voltage VSS.
- the high-voltage matching line HML 1 is the parasitic capacitance CSH 1, CSH
- the search nodes SL 1 1, SL 1 2 via the parasitic capacitance CNH 1 and the storage node N 1 via the CNH 2 N 2 is bonded to each. Among them, the voltage of the high-voltage side match line HML1 rises due to the coupling with the activated search line SL11.
- search line driving noise is generated in the high voltage match line HML1.
- the actual search key which is omitted in the figure, is information composed of a plurality of bits
- the search line driving noise VNC shown in the figure is a value corresponding to the number of search line drives.
- the low-voltage side match line LML 1 is coupled to the storage nodes N 1 and N 2 via the parasitic capacitances CNL 1 and CNL 2 and to the search lines SL ll and SL 12 via the parasitic capacitances CSL 1 and CSL 2, respectively. are doing.
- the search line SL 11 is driven, but as described above, since the parasitic capacitance CSL 1 is extremely small, the voltage rise of the low-voltage side match line L ML 1 due to the coupling with the search line SL 11 is The high-voltage side match line is negligibly small compared to HML1. Therefore, in the figure, the voltage of the low-voltage side match line LML1 after the start of the search line SL11 is set to the ground voltage VSS.
- the transistor T5 of the memory cell MC11 is turned on.However, since the transistor T6 is in the cut-off state, a current flows to the storage node N2 side of the comparison circuit CP. Not flowing. Further, since the transistor T3 is kept in the cut-off state, no current flows to the storage node N1.
- the comparison circuit CP of the memory cell MC 11 is in a matching state.
- the high-voltage match line HML1 is maintained at the precharge voltage VH or higher (here, the power supply voltage VDD or higher), and the low-voltage match line LML1 is maintained at the ground voltage VSS.
- the match determination circuit MD1 discriminates that the voltage of the high-voltage side match line HML1 is higher than the reference voltage VRH and a voltage equal to or higher than the positive comparison signal voltage (VS IG) is generated. Detects a match in the entry on the first line.
- the search line SL 11 which is the power supply voltage VDD, is driven to the ground voltage VSS, and the precharge enable signal PC, which is the ground voltage VSS, is driven to the boosted voltage VDH to match the match line pair.
- a search operation when the search key and the entry are different will be described with reference to FIGS.
- the operation of inputting the search key after the precharged match line pair is in the floating state is as described above.
- a search operation in a case where the information of the search key to be compared with the storage information of the memory cell MC 11 is “0” will be described.
- the search line SL11 is held at the ground voltage VSS, while the search line SL11 is held at the ground voltage VSS.
- the search line SL21 which is at VSS, is driven to the power supply voltage VDD.
- the voltage of the high-voltage side match line HML1 increases due to the coupling with the search line SL21 via the parasitic capacitance CSH2.
- the transistor T3 of the memory cell MC11 is turned on, and a current path is formed on the storage node N1 side of the comparison circuit CP. Short-circuited. That is, the high-voltage side match line HML1, which has been precharged to the power supply voltage VDD, is discharged toward the vicinity of the intermediate voltage VDD / 2, and the low-voltage side match line, which has been precharged to the ground voltage VSS. LML 1 is charged toward the intermediate voltage VDD / 2.
- the match determination circuit MD1 discriminates that a negative comparison signal voltage (one VSIG) is generated when the voltage of the high-voltage side match line HML1 falls below the reference voltage VRH by VSIG, and It is determined that the entries in one line do not match.
- the search line SL21 which is at the power supply voltage VDD, is driven to the ground voltage VSS, and the precharge enable signal PRE, which is at the ground voltage VSS, is driven to the boosted voltage VDH, and the match line is driven.
- the search operation is completed by precharging each pair.
- the match line pair is short-circuited by the current paths formed in the multiple memory cells. Therefore, it is apparent that the voltage reaches the intermediate voltage VDDZ 2 around earlier than the waveform shown. That is, the high voltage match line HML1 reaches the voltage level (VR-VSIG) in a time shorter than the illustrated comparison time t2.
- the match line pair is designed to have the same parasitic capacitance, but the match detection circuit is connected to only one of the high-voltage side match lines HML1. Considering that the load capacity imbalance caused by the short circuit and the search line drive noise are generated only on one high-voltage side match line HM L1, the voltage of the match line pair after the short circuit is the intermediate voltage VDD. / 2 explained as near.
- the first effect is that power consumption can be reduced.
- the match line pair which has been precharged to different voltages, is put into a floating state, and then a search key is input via the search line pair, so that a signal corresponding to the comparison result of information is charged. Since the voltage is generated in the high voltage side match line by the operation, the voltage amplitude of the high voltage side match line can be suppressed to about half of the precharge voltage difference between the pair of matching lines. Accordingly, the power required for the precharge operation of the match line can be reduced.
- the second effect is that the time required for the search operation can be reduced. Since the match line pair is coupled to the search line pair via the parasitic capacitances CSH1, CSH2, CSL1, and C.SL2, search line drive noise is generated in the match line pair. However, since the parasitic capacitances CSL 1 and CSL 2 are extremely small, the voltage rise on the low-voltage side match line is negligibly small. Therefore, the transistors T 3, T 4, T 5, and T 6, which compare information, can avoid a decrease in drive capability due to a decrease in the gate-source voltage or an increase in the threshold voltage due to the substrate bias effect. Thus, the comparison time can be reduced. That is, the time required for the search operation can be reduced.
- the third effect is that the introduction of a self-aligned process widely used in general-purpose DRAMs can reduce the mask alignment margin.
- the transistor T 3 The gate electrode of T5 is formed in an L shape, and the gate electrodes of the transistors T4 and T6 and the two word lines are arranged at a minimum distance. Further, the gate electrodes of the transistors T3, T4, T5, T6 are arranged in parallel with each other at a minimum interval. With the above layout, the first and third contacts can be formed between the gate electrodes using a self-alignment process, so that the area of the memory cell can be reduced.
- the fourth effect is that a TDCAM cell can be formed in the same processing steps as general-purpose DRAM. That is, similar to a circuit block arranged outside the memory array, the connection between the internal nodes of the memory cells can be realized by using the first and third contacts and the first metal layer. The DRAM processing process can be applied as it is.
- the fifth effect is that the cell area can be suppressed by sharing a connection portion between a memory cell and a bit line pair, a search line pair, or a match line pair with an adjacent memory cell.
- the sixth effect is that the load capacity of the match line pair can be made substantially the same. That is, first, the connection part between the low-voltage side match line and the memory cell is shared with the adjacent memory cell, and the match line pair is formed using the same second metal layer, so that the side wall insulating film is formed. Therefore, the load capacitance of the match line pair can be made almost the same value while the parasitic capacitance generated on the low voltage side match line is the same as that of the high voltage side match line. It can be almost the intermediate voltage VDD / 2. Therefore, it is possible to realize a stable charge sharing operation in which the voltage amplitude of the match line pair is suppressed to almost half of the power supply voltage V DD while generating a sufficiently large comparison signal voltage. With the above six effects, it is possible to realize a large-capacity TCAM that performs a search operation at low power and at high speed.
- FIG. 14 shows a memory array configuration when the simplified equivalent circuit model of the memory cell described in FIGS. 8 and 9 is applied to FIG. Below, Figure 15 and Figure 1 According to 6, the search operation in the memory array of FIG. 14 will be described.
- Figure 15 shows the search operation timing when the search key and the entry match.
- the pre-charged pair of matching wires is set to the floating state and then grounded.
- the search line SL11 which is at the voltage VSS, is driven to the power supply voltage VDD.
- the high-voltage matching line HML1 which is coupled to the search line SL11 via the parasitic capacitance CSH1, is raised to a voltage higher than the precharge voltage VH (here, the power supply voltage VDD) by the search line drive noise. It is kept as it is.
- the low voltage side match line L ML 1 is coupled to the search line SL 11 1 via the parasitic capacitance CSL 1, but since the coupling is weak, the search line drive noise is so small that it can be ignored. It is kept at the precharge voltage (here, the ground voltage VSS).
- the reference voltage VRL is set to a voltage higher than the ground voltage VSS by VS IG, and the match determination circuit MD1 outputs a negative comparison signal (here, one VSIG) is generated on the low-voltage side match line LML1, and it is determined that the first entry matches.
- a negative comparison signal here, one VSIG
- FIG. 16 shows the search operation timing when the search key and the entry are different.
- the precharged match line pair is put into a floating state.
- the search line SL 21 having the ground voltage VSS is driven to the power supply voltage V DD.
- the match determination circuit MD1 By discriminating that a positive comparison signal (here, VSIG) has been generated on the side match line LML1, it is determined that the first entry did not match.
- a positive comparison signal here, VSIG
- the search operation takes less time than the memory array in Figure 1. Can be performed. That is, as described with reference to FIG. 11, in the memory array configuration of FIG. 1, the voltage of the non-matching high-voltage side match line rises due to search line driving noise and is discharged before being discharged. The time (comparison time T2) required to generate (one VSIG) is long.
- the comparison time t 3 shown in FIG. 16 is shorter than the time t 2. Therefore, the configuration in which the match determination circuit is connected to the low-voltage side match line as shown in FIG. 14 enables the search operation to be performed in a shorter time.
- FIG. 17 shows a memory array according to the present embodiment, and shows a configuration having m ⁇ n-bit memory cells as in FIG.
- the memory cell is composed of two capacitors and six transistors.
- the corresponding two data lines are referred to as a data line pair.
- the read / write circuit block RWB is composed of a plurality of sense amplifiers connected to the data lines and a precharge circuit as described in FIG. 1 of the first embodiment.
- these sense amplifiers drive the data lines to a voltage corresponding to the stored information (entry) or the comparison information (search key). That is, binary information (information '
- the search line drive circuit SLD for driving the search line pairs in the column direction as shown in FIGS. 13 and 1 can be eliminated, and the array area can be reduced.
- the configuration is shown in which the match decision circuit MDs (1, 2, ⁇ , m) is connected to the low-voltage side matching line LMLs (1, 2, ⁇ , m). Also, it is possible to connect to the high voltage side match line HMLs (1, 2,..., M).
- the configuration shown in FIG. 17 is more suitable for shortening the search time.
- the layout and structure of the memory cell as described in Embodiment 1 with reference to FIGS. 2 to 7 it is possible to realize a memory cell having a small area.
- FIG. 18 shows a block diagram of a memory array according to the third embodiment, together with power supply voltages supplied to the respective memory arrays.
- This memory array is, for example, a block of the memory array configuration shown in FIG. 13.
- a memory array MA is surrounded by a precharge circuit block PB composed of a plurality of precharge circuits, and a plurality of match detection circuits.
- a match detection circuit MDB, a row decoder XDE (:, a search line drive circuit S LD, and a read / write circuit block RWB are arranged.
- a precharge enable signal drive circuit PCD for driving the precharge enable signal PC, a power supply voltage generation circuit VGEN, and an array control circuit ACT L are added.
- the feature of the third embodiment is that a power supply voltage generation circuit VGEN is used to generate a bit line voltage VBL higher than a power supply voltage VDD which is a high voltage level of a search line, and to store a logical value '1'. By driving the node voltage to a voltage higher than the power supply voltage VDD, the read operation of stored information can be performed accurately.
- the power supply voltage generator VGEN uses the power supply voltage VDD input from outside the chip. In addition, receiving boost voltage VDH, VPP, bit line voltage VBL, reference voltage VRL, VBLR, and precharge voltage VH, VL in response to ground voltage VSS.
- the search line drive circuit SLD which is the first circuit block, receives the power supply voltage VDD and the ground voltage VSS, respectively, and turns the search line pair from the ground voltage VSS to the power supply. Drive to voltage VDD respectively.
- the precharge enable signal drive circuit PCD which is a second circuit block, receives the boosted voltage VDH and the ground voltage VSS, and drives the precharge enable signal PC from the ground voltage VSS to the boosted voltage VDH.
- the boosted voltage VDH is set to a voltage higher than the power supply voltage VDD and higher than the threshold voltage VTN of the NMOS transistor in the precharge circuit block PB as described in the first embodiment.
- the second circuit block, the array control circuit ACTL receives the power supply voltage VDD, the ground voltage VSS, the bit line voltage VB L, and the reference voltage VB LR, and receives a common source according to the input timing of the address. It drives the lines CSP and CSN, the bit line equalize signal BL EQ, and the read / write enable signal RWE.
- the read / write circuit block RWB which is the third circuit block, has a common source line CSP, CSN, a bit line equalize signal BLEQ, and a read / write enable signal RWE. Receiving each of the voltages VBLR, each bit line pair is driven to a voltage corresponding to the stored information (entry).
- FIG. 19 shows a read / write circuit RWC 11 arranged on a bit line BL 11 as an example of a configuration of an element circuit of the read / write circuit block RWB.
- the sense amplifier S A is a cross force ripple type latch known for general-purpose DRAMs, comprising two PMOS transistors T 10 and T 11 and two NMOS transistors T 12 and T 13.
- the sources of the transistors ⁇ ⁇ ⁇ and ⁇ ⁇ ⁇ ⁇ are connected to the common source line CSP, and the sources of the transistors T12 and T13 are connected to the common source line CSN, respectively, and the bit line BL11 and the dummy bit line BLD1 are connected. Discriminates and amplifies the small voltage difference generated between the two.
- the equalizing circuit PE has a known configuration composed of three NMOS transistors T 20, ⁇ 21, and 2 22. According to the bit line equalizing signal BL EQ, the bit Itoizumi BL 11, And the dummy bit line BLD11 is driven to the reference voltage VBLR.
- the column switch circuit YSW is composed of NMOS transistors ⁇ 30 and ⁇ 31, and is connected to the bit line BL11, the input / output line I ⁇ 11, and the dummy bit line BLD111 according to the read / write enable signal RWE. Connect the output lines I ⁇ ⁇ 1 1 respectively.
- the dummy capacitance CD is equal to the load capacitance of the bit line BL 11 and the dummy bit line B LD 11 in order to accurately separate and amplify the minute voltage generated on the bit line BL 11 It is a capacity designed as follows.
- the memory cell MC 11 in the memory array MA in FIG. 18 holds the storage information '1', and the memory cell MC 1 in ⁇ 13 Assume that the logical value of storage node N 1 of 1 is '1'.
- bit line equalizing signal BLEQ is driven to the boost voltage VPP to turn on the transistors in the equalizing circuit PE, so that the bit line BL 11 and dummy bit line BLD 11 are connected to the reference voltage VB. Drive to LR respectively.
- the boosted voltage VPP is set so that the source-drain voltage of the transistors T20, T21, and T22 becomes sufficiently larger than the threshold voltage VTN1.
- the voltage is set higher than the threshold voltage VTN1 for the bit line voltage VBL. That is, there is a relationship of VP P> VB L + VTN 1.
- the equalizing circuit PE is cut off by driving the bit line equalizing signal B PRE, which is the boosted voltage VPP, to the ground voltage VSS, and the lead line WL1, which is at the ground voltage VSS, is turned off. Is driven to the boost voltage VPP, the transistor T1 in the memory cell MC11 in FIG. 13 is turned on, and a very small voltage is generated on the bit line BL11.
- the common source line CSP which is the reference voltage VB LR, is driven to the bit line voltage VBL, and the common source line CSN is driven to the ground voltage VSS to activate the sense amplifier SA. And amplify.
- the reference voltage VB LR is set to the intermediate voltage VB L / 2 between the bit line voltage VBL and the ground voltage VSS, and the logical value '1' of the storage node N1 of the memory cell MC11 is set.
- the example shows that the voltage of the bit line BL11 slightly increases in response to the change in the voltage. Therefore, the sense amplifier SA discriminates the voltage of the bit line BL 11 from the voltage of the dummy bit line BLD 11 and sets the bit line BL 11 to the bit line voltage VBL and the dummy bit line BLD 11 to the ground voltage VSS. Drive each.
- the storage node N1 (not shown) is driven near the bit line voltage VBL.
- drive the lead line WL which is the boosted voltage VPP, to the ground voltage VSS to turn off the transistor T1 in the memory cell, and then apply the equalize signal BLEQ, which is at the ground voltage VSS.
- the precharge circuit PE By driving the boosted voltage VPP, the bit line BL11 and the dummy bit line BLD11 are driven to the reference voltage VBLR, respectively, and the refresh operation is completed.
- the memory array shown in FIG. 18 has the following effects. That is, a voltage (here, the bit line voltage VBL) higher than the high voltage level of the search line (here, the power supply voltage VDD) is generated using the voltage generator VGEN, and read / write via the array control circuit ACTL. By supplying the circuit block RWB, the bit line can be driven to a higher voltage than the search line.
- VBL bit line voltage
- VDD power supply voltage
- the storage node can be driven to a sufficiently high voltage. In other words, stable reading and writing with a large noise margin It is possible to further reduce the power consumption in the search operation while maintaining the search operation and the refresh operation.
- the memory array configuration and operation that generate a bit line voltage VBL higher than the power supply voltage VDD has been described.
- the power supply voltage VDD is a bit line
- the storage node has a negative voltage level of the storage node.
- TCAM high-speed search operation is required. To drive the search line at high speed, a stable power supply voltage VDD input from the outside must be set to the high voltage level of the search line. It is desirable. Therefore, the configuration in FIG. 18 is optimal.
- FIG. 19 shows a read / write circuit configuration in which a dummy capacitor CD is connected to the dummy bit line BLD11.
- a configuration in which the read / write circuit block; RWB is shared by the two memory arrays is also possible.
- This configuration can be easily understood from the open bit line configuration widely known in general-purpose DRAM.
- the load capacities of the bit lines can be equalized without the dummy capacity CD. That is, the circuit design is facilitated, and the read operation and the refresh operation can be performed stably.
- the power supply voltage generator VGEN When applied to Fig. 17, the power supply voltage generator VGEN generates VRH instead of the reference voltage VRL so that the match determination circuit can discriminate the comparison signal voltage generated on the high-voltage side match line. , Supplied to the match determination circuit block MDB.
- the high voltage level of the data line pair is switched to the power supply voltage VDD during the search operation and to the bit line voltage VBL during the read / write operation and refresh operation, depending on the operation. That is easy to understand.
- the refresh operation has been described in FIG.
- the read / write enable signal RWE which is at the ground voltage VSS, is driven to the power supply voltage VDD before the activated read line falls.
- the voltage setting according to the third embodiment is not limited to the memory arrays according to the first and second embodiments described above, but can be applied to a memory array using the memory cells illustrated in FIG. .
- the storage node is driven to a sufficiently high voltage to enable stable read / write and refresh operations with a large noise margin, while lowering the power supply voltage VDD to search. Power consumption in operation can be further reduced.
- TCAMs having various memory array configurations have been described according to the first to third embodiments.
- the present invention is not limited to the TCAMs, and the binary content addressable memory used in voice recognition, image recognition, and the like is used. It is also possible to apply to
- the TCAM according to the present invention is not limited to an off-chip, that is, a single device, but can also be applied to a TCAM block mounted on a system LSI called a so-called system-on-chip (SoC).
- SoC system-on-chip
- the present invention is not limited to a memory cell having a storage circuit including two transistors and two capacitors, but also includes a known static random access memory (SRAM) including six transistors. It can also be applied to a memory array composed of memory cells having a storage circuit composed of In any case, the same effect as that described in each embodiment can be obtained.
- SRAM static random access memory
- the comparison signal voltage is generated on the match line pair by the charge sharing operation, and the parasitic capacitance between the pair and the search line is smaller.
- a match decision circuit to discriminate the comparison signal generated on the low-voltage side match line, it is possible to perform a search operation that avoids the effects of search line drive noise, and is suitable for technology that performs the search operation with low power and high speed. I have.
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Priority Applications (5)
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JP2005510763A JPWO2005050663A1 (ja) | 2003-11-21 | 2003-11-21 | 半導体集積回路装置 |
PCT/JP2003/014901 WO2005050663A1 (ja) | 2003-11-21 | 2003-11-21 | 半導体集積回路装置 |
EP03774141A EP1688957A4 (en) | 2003-11-21 | 2003-11-21 | INTEGRATED SEMICONDUCTOR CIRCUIT ELEMENT |
US10/579,911 US7619911B2 (en) | 2003-11-21 | 2003-11-21 | Semiconductor integrated circuit device |
CNA2003801108225A CN1906699A (zh) | 2003-11-21 | 2003-11-21 | 半导体集成电路器件 |
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PCT/JP2003/014901 WO2005050663A1 (ja) | 2003-11-21 | 2003-11-21 | 半導体集積回路装置 |
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US (1) | US7619911B2 (ja) |
EP (1) | EP1688957A4 (ja) |
JP (1) | JPWO2005050663A1 (ja) |
CN (1) | CN1906699A (ja) |
WO (1) | WO2005050663A1 (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105913870A (zh) * | 2015-02-25 | 2016-08-31 | 瑞萨电子株式会社 | 半导体存储器装置 |
US9836238B2 (en) | 2015-12-31 | 2017-12-05 | International Business Machines Corporation | Hybrid compression for large history compressors |
US10067705B2 (en) | 2015-12-31 | 2018-09-04 | International Business Machines Corporation | Hybrid compression for large history compressors |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8073648B2 (en) * | 2007-05-14 | 2011-12-06 | Sandisk Il Ltd. | Measuring threshold voltage distribution in memory using an aggregate characteristic |
JP5477621B2 (ja) * | 2009-08-03 | 2014-04-23 | ルネサスエレクトロニクス株式会社 | 連想メモリ |
US8320209B2 (en) * | 2010-05-05 | 2012-11-27 | Stmicroelectronics International N.V. | Sense amplifier using reference signal through standard MOS and DRAM capacitor |
CN102881331A (zh) * | 2011-07-15 | 2013-01-16 | 复旦大学 | 灵敏放大器的控制电路及包括其的dram |
US8582380B2 (en) | 2011-12-21 | 2013-11-12 | Micron Technology, Inc. | Systems, circuits, and methods for charge sharing |
US8861285B2 (en) * | 2012-02-09 | 2014-10-14 | Micron Technology, Inc. | Apparatuses and methods for line charge sharing |
US9214231B2 (en) | 2013-01-31 | 2015-12-15 | Hewlett-Packard Development Company, L.P. | Crossbar memory to provide content addressable functionality |
US9947406B2 (en) * | 2015-02-23 | 2018-04-17 | Qualcomm Incorporated | Dynamic tag compare circuits employing P-type field-effect transistor (PFET)-dominant evaluation circuits for reduced evaluation time, and related systems and methods |
CN118038934A (zh) * | 2022-11-04 | 2024-05-14 | 长鑫存储技术有限公司 | 存储器和控制方法 |
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JP2000132978A (ja) * | 1998-10-29 | 2000-05-12 | Internatl Business Mach Corp <Ibm> | 連想メモリ(cam) |
JP2001319481A (ja) * | 2000-03-03 | 2001-11-16 | Kawasaki Steel Corp | 連想メモリ装置 |
JP2002541610A (ja) * | 1999-03-31 | 2002-12-03 | モサイド・テクノロジーズ・インコーポレイテッド | ダイナミック連想記憶セル |
JP2003303495A (ja) * | 2002-04-09 | 2003-10-24 | Fujitsu Ltd | 半導体記憶装置 |
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US6343029B1 (en) * | 2001-02-13 | 2002-01-29 | Silicon Access Networks, Inc. | Charge shared match line differential generation for CAM |
JP2003100086A (ja) | 2001-09-25 | 2003-04-04 | Fujitsu Ltd | 連想メモリ回路 |
US7116593B2 (en) * | 2002-02-01 | 2006-10-03 | Hitachi, Ltd. | Storage device |
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2003
- 2003-11-21 WO PCT/JP2003/014901 patent/WO2005050663A1/ja not_active Application Discontinuation
- 2003-11-21 US US10/579,911 patent/US7619911B2/en not_active Expired - Fee Related
- 2003-11-21 EP EP03774141A patent/EP1688957A4/en not_active Withdrawn
- 2003-11-21 JP JP2005510763A patent/JPWO2005050663A1/ja active Pending
- 2003-11-21 CN CNA2003801108225A patent/CN1906699A/zh active Pending
Patent Citations (5)
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JP2000132978A (ja) * | 1998-10-29 | 2000-05-12 | Internatl Business Mach Corp <Ibm> | 連想メモリ(cam) |
JP2002541610A (ja) * | 1999-03-31 | 2002-12-03 | モサイド・テクノロジーズ・インコーポレイテッド | ダイナミック連想記憶セル |
JP2001319481A (ja) * | 2000-03-03 | 2001-11-16 | Kawasaki Steel Corp | 連想メモリ装置 |
JP2003303495A (ja) * | 2002-04-09 | 2003-10-24 | Fujitsu Ltd | 半導体記憶装置 |
JP2004128266A (ja) * | 2002-10-03 | 2004-04-22 | Fujitsu Ltd | 半導体装置 |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105913870A (zh) * | 2015-02-25 | 2016-08-31 | 瑞萨电子株式会社 | 半导体存储器装置 |
JP2016157500A (ja) * | 2015-02-25 | 2016-09-01 | ルネサスエレクトロニクス株式会社 | 半導体記憶装置 |
CN105913870B (zh) * | 2015-02-25 | 2021-04-16 | 瑞萨电子株式会社 | 半导体存储器装置 |
US9836238B2 (en) | 2015-12-31 | 2017-12-05 | International Business Machines Corporation | Hybrid compression for large history compressors |
US10067705B2 (en) | 2015-12-31 | 2018-09-04 | International Business Machines Corporation | Hybrid compression for large history compressors |
Also Published As
Publication number | Publication date |
---|---|
EP1688957A4 (en) | 2007-03-28 |
US7619911B2 (en) | 2009-11-17 |
EP1688957A1 (en) | 2006-08-09 |
US20070274144A1 (en) | 2007-11-29 |
CN1906699A (zh) | 2007-01-31 |
JPWO2005050663A1 (ja) | 2007-08-23 |
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