WO2010109803A1 - 抵抗変化型不揮発性記憶装置 - Google Patents
抵抗変化型不揮発性記憶装置 Download PDFInfo
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- WO2010109803A1 WO2010109803A1 PCT/JP2010/001833 JP2010001833W WO2010109803A1 WO 2010109803 A1 WO2010109803 A1 WO 2010109803A1 JP 2010001833 W JP2010001833 W JP 2010001833W WO 2010109803 A1 WO2010109803 A1 WO 2010109803A1
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- H—ELECTRICITY
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- H01L27/00—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate
- H01L27/02—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier
- H01L27/04—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body
- H01L27/10—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration
- H01L27/101—Devices consisting of a plurality of semiconductor or other solid-state components formed in or on a common substrate including semiconductor components specially adapted for rectifying, oscillating, amplifying or switching and having at least one potential-jump barrier or surface barrier; including integrated passive circuit elements with at least one potential-jump barrier or surface barrier the substrate being a semiconductor body including a plurality of individual components in a repetitive configuration including resistors or capacitors only
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- 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
- G11C11/56—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency
- G11C11/5685—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency using storage elements comprising metal oxide memory material, e.g. perovskites
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- G—PHYSICS
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- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/0002—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements
- G11C13/0007—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements comprising metal oxide memory material, e.g. perovskites
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/0002—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements
- G11C13/0021—Auxiliary circuits
- G11C13/003—Cell access
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/0002—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using resistive RAM [RRAM] elements
- G11C13/0021—Auxiliary circuits
- G11C13/0038—Power supply circuits
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B63/00—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices
- H10B63/30—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices comprising selection components having three or more electrodes, e.g. transistors
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- H—ELECTRICITY
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- H10B—ELECTRONIC MEMORY DEVICES
- H10B63/00—Resistance change memory devices, e.g. resistive RAM [ReRAM] devices
- H10B63/80—Arrangements comprising multiple bistable or multi-stable switching components of the same type on a plane parallel to the substrate, e.g. cross-point arrays
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B69/00—Erasable-and-programmable ROM [EPROM] devices not provided for in groups H10B41/00 - H10B63/00, e.g. ultraviolet erasable-and-programmable ROM [UVEPROM] devices
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C2213/00—Indexing scheme relating to G11C13/00 for features not covered by this group
- G11C2213/70—Resistive array aspects
- G11C2213/75—Array having a NAND structure comprising, for example, memory cells in series or memory elements in series, a memory element being a memory cell in parallel with an access transistor
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C2213/00—Indexing scheme relating to G11C13/00 for features not covered by this group
- G11C2213/70—Resistive array aspects
- G11C2213/79—Array wherein the access device being a transistor
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- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/011—Manufacture or treatment of multistable switching devices
- H10N70/021—Formation of the switching material, e.g. layer deposition
- H10N70/026—Formation of the switching material, e.g. layer deposition by physical vapor deposition, e.g. sputtering
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- H—ELECTRICITY
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- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/20—Multistable switching devices, e.g. memristors
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- H—ELECTRICITY
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- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/821—Device geometry
- H10N70/826—Device geometry adapted for essentially vertical current flow, e.g. sandwich or pillar type devices
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N70/00—Solid-state devices without a potential-jump barrier or surface barrier, and specially adapted for rectifying, amplifying, oscillating or switching
- H10N70/801—Constructional details of multistable switching devices
- H10N70/881—Switching materials
- H10N70/883—Oxides or nitrides
- H10N70/8833—Binary metal oxides, e.g. TaOx
Definitions
- the present invention relates to a variable resistance nonvolatile memory device having a memory cell composed of a variable resistance element whose resistance value reversibly changes based on an electrical signal and a transistor.
- the resistance change element refers to an element having a property that the resistance value reversibly changes by an electrical signal, and further capable of storing data corresponding to the resistance value in a nonvolatile manner.
- a so-called cross-point structure is used for one of the memory cells using the resistance variable element.
- each memory cell is configured by being sandwiched between a bit line and a word line at a position of an intersection between a bit line and a word line arranged orthogonally.
- a memory cell area of 4F 2 can be realized.
- Patent Document 1 discloses a cross-point variable resistance storage device using a bipolar variable resistance element. In this resistance change type memory device, Vpp is applied to the selected bit line, Vss (0 V) is applied to the selected word line, and 1/2 Vpp is applied to the unselected word line and unselected bit line at the time of data writing. In data erasure, Vpp is applied to the selected word line, Vss (0 V) is applied to the selected bit line, and Vpp / 2 is applied to the unselected word line and the unselected bit line.
- nonvolatile memory device using a resistance change element a so-called 1T1R in which a MOS transistor and a resistance change element are connected in series at the intersection of a bit line, a word line, and a source line arranged orthogonally.
- a nonvolatile memory device in which memory cells called “types” are arranged in a matrix is generally known. Area of the memory cell is required to 6F 2 at minimum.
- Patent Document 2 discloses a nonvolatile memory device including 1T1R type memory cells using an oxide having a perovskite crystal structure as a resistance change element.
- FIG. 47 is a schematic diagram of a cross section of a memory cell disclosed in FIG.
- the memory cell 1011 is formed by electrically connecting a transistor 1006 and a resistance change element 1010 in series.
- the transistor 1006 includes a source region 1002 which is a first diffusion layer region manufactured over a semiconductor substrate 1001, a drain region 1003 which is a second diffusion layer region, and a gate electrode 1005 formed on the gate oxide film 1004. .
- the resistance change element 1010 is formed by sandwiching a variable resistance layer 1008 whose resistance value changes with voltage application between a lower electrode 1007 and an upper electrode 1009.
- the drain region 1003 and the lower electrode 1007 are electrically connected.
- the upper electrode 1009 is connected to the metal wiring to be the bit line 1012, the gate electrode 1005 is connected to the word line, and the source region 1002 is connected to the metal wiring to be the source line 1013.
- Pr 1-x Ca x MnO 3 , La 1-x Ca x MnO 3 (PCMO) and the like are disclosed as materials used for the variable resistance layer 1008, but no particular mention is made regarding the electrode material. .
- Patent Document 3 and Patent Document 4 disclose structures in which the memory cell area can be realized to 4F 2 by using the 1T1R memory structure.
- FIG. 48 is a circuit diagram disclosed in FIG. Here, the resistance change element and the transistor are arranged in parallel to constitute a memory cell. Memory cells are connected in series to form a memory array. With this arrangement, the area of the memory cell is determined by the area of the transistor and can be realized up to 4F 2 .
- Patent Document 2 which is smaller than the memory cell area of 1T1R 6F 2 , a cross-point type resistance change memory device using a varistor as a rectifying element is disclosed.
- a diode is used as a rectifying element in a cross-point type resistance change memory device.
- the diode has a characteristic that current increases exponentially with voltage. The value of the current flowing through the diode is not completely zero even if the applied voltage is lower than the threshold voltage Vth.
- Patent Document 3 and Patent Document 4 since the resistance change element and the transistor are arranged in parallel, when one cell among the memory cells arranged in series is selected, all the transistors arranged in the same column are in the ON state. The voltage between the source and drain is also applied to the resistance change element that is not selected. Further, since the low resistance of the variable resistance element is several hundred ohms and the ON resistance of the transistor is about 1 k ⁇ , more current flows through the low resistance variable resistance element than the current flowing through the transistor, and the memory characteristics deteriorate.
- the present invention solves the above problems, and by devising a structure in which a variable resistance element is arranged, a nonvolatile memory that realizes a memory cell of 4F 2 while effectively suppressing a current flowing through a non-selected memory cell.
- the main purpose is to provide a storage device.
- a nonvolatile memory device includes a plurality of first wirings extending in parallel to each other in a first direction in a first plane, and a second in a second plane parallel to the first plane.
- a plurality of second wirings extending parallel to each other and three-dimensionally intersecting the first wiring, and memory cells provided corresponding to the three-dimensional intersections of the first wiring and the second wiring, respectively.
- Each of the memory cells includes one transistor and one variable resistance element, and each of the transistors includes a first main terminal, a second main terminal, and a control terminal, and the variable resistance element Each of which includes a first electrode, a second electrode, a resistance change layer provided between the first electrode and the second electrode, and is adjacent to the plurality of memory cells arranged along the first direction. 2 memory cells By connecting the first main terminal of one of the included memory cells and the second main terminal of the other memory cell, the main terminals of the plurality of memory cells are sequentially connected in series to extend in the first direction.
- a serial path is formed, and for each of the memory cells, a control terminal is connected to a first wiring corresponding to the memory cell, a second electrode is connected to a second wiring corresponding to the memory cell, and the first electrode is A series path corresponding to the memory cell is connected.
- Such a configuration provides a nonvolatile memory device that realizes a 4F 2 memory cell while effectively suppressing the current flowing through the non-selected memory cells.
- the nonvolatile memory device includes a plurality of third wirings extending in parallel with each other in the first direction, and a plurality of memory cells arranged along the first direction are formed by a predetermined number of memory cells arranged in series. And the series path may be connected to the third wiring for each memory block.
- both ends of the series path may be connected to the third wiring for each memory block.
- the nonvolatile memory device includes a power supply circuit for applying a voltage to the resistance variable element included in each memory cell, and the power supply circuit corresponds to the corresponding series path for the selected memory cell.
- the output voltage may be changed according to the number of transistors included in the series path from the connection portion with the third wiring to the first electrode of the memory cell.
- the voltage applied between both electrodes of the resistance variable element is constant regardless of the position of the memory cell, the resistance value after writing is kept more constant than in the previous structure, and the resistance variable element It is possible to further suppress unnecessary voltage stress.
- the first main terminal and the second main terminal may each have a silicide layer, and the silicide layer may constitute the first electrode.
- the silicide layer may be made of platinum silicide.
- the present invention can provide a nonvolatile memory device having the above-described configuration and realizing a 4F 2 memory cell while effectively suppressing a current flowing through a non-selected memory cell.
- FIG. 1 is a block diagram showing an example of a circuit configuration of the nonvolatile memory device 100 according to the first embodiment of the present invention.
- FIG. 2 is an enlarged view of the memory cell MC portion in FIG. The subscript indicates the row or column number of the corresponding memory block.
- FIG. 3 is a diagram showing one memory block
- FIG. 3 (a) is a top view of the memory block
- FIG. 3 (b) is an equivalent circuit diagram of FIG. 3 (a).
- 4 is a diagram showing a cross section of the memory block indicated by the alternate long and short dash line in FIG. 3.
- FIG. 4A is a cross sectional view taken along the line AA ′ in FIG. 3
- FIG. 3 is a cross-sectional view taken along line BB ′ in FIG. 3, FIG.
- FIG. 5 is a diagram illustrating an example of characteristics (relationship between voltage and resistance value) of the resistance variable element included in the nonvolatile memory device according to Embodiment 1 of the present invention.
- FIG. 6 is a timing chart showing an operation example of the nonvolatile memory device according to Embodiment 1 of the present invention.
- FIG. 6A shows a case where “0” is written in the memory cell MC00 00 (resistance change element RR).
- FIG. 6B shows a case where “1” is written in the memory cell MC00 00 (when the resistance variable element RR is increased in resistance), and
- FIG. 6C shows a case where the memory cell MC00 00 has a low resistance. The case where the written data is read is shown.
- FIG. 7 is a top view showing a step of forming a polysilicon layer on a P-type silicon substrate.
- FIG. 8 is a cross-sectional view showing a process of forming a polysilicon layer on a P-type silicon substrate.
- FIG. 8A is a cross-sectional view taken along the line AA ′ in FIG.
- FIG. 8B is a cross-sectional view taken along the line BB ′ in FIG. 7 as seen in the direction of the arrow
- FIG. 8C is a cross-sectional view taken along the line CC ′ in FIG.
- FIG. 8D is a cross-sectional view taken along the line DD ′ in FIG. 7, and a cross-sectional view taken in the direction of the arrow is shown in FIG. 8E.
- FIG. 8F is a cross-sectional view of the cross section cut along FF ′ in FIG. 7 as viewed in the direction of the arrow.
- FIG. 9 is a top view showing a step of forming a trench for forming an STI by etching a P-type silicon substrate and a polysilicon layer.
- FIG. 9 is a top view showing a step of forming a trench for forming an STI by etching a P-type silicon substrate and a polysilicon layer.
- FIG. 10 is a cross-sectional view showing a step of forming a trench for forming an STI by etching a P-type silicon substrate and a polysilicon layer
- FIG. 10 (a) is taken along line AA ′ in FIG.
- FIG. 10B is a cross-sectional view taken along the line BB ′ in FIG. 9
- FIG. 10C is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 10 (d) is a cross-sectional view taken along the line CC ′ in FIG. 9
- FIG. 11 is a top view showing a step of forming STI by embedding silicon dioxide in the groove.
- FIG. 12 is a cross-sectional view showing a step of forming STI by embedding silicon dioxide in the groove.
- FIG. 12A is a cross-sectional view taken along the line AA ′ in FIG.
- FIG. 12B is a cross-sectional view taken along the line BB ′ in FIG. 11 as seen in the direction of the arrow.
- FIG. 12C is a cross-sectional view taken along the line CC ′ in FIG. FIG.
- FIG. 12D is a cross-sectional view taken along the line DD ′ in FIG. 11 and FIG. 12E is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 12F is a cross-sectional view of the cross section cut along FF ′ in FIG. 11 as viewed in the direction of the arrow.
- FIG. 13 is a top view showing a step of forming a Si 3 N 4 layer so as to cover the silicon dioxide layer and the polysilicon layer.
- FIG. 14 is a cross-sectional view showing a process of forming a Si 3 N 4 layer so as to cover the silicon dioxide layer and the polysilicon layer, and FIG. 14A is cut along AA ′ in FIG. FIG.
- FIG. 14B is a cross-sectional view taken along the line BB ′ in FIG. 13 and FIG. 14C is a cross-sectional view taken along the line CC ′ in FIG.
- FIG. 14D is a cross-sectional view taken along the line DD ′ in FIG. 13
- FIG. 14E is a cross-sectional view taken along the line DD ′ in FIG. 13 is a cross-sectional view taken along the line EE ′ as seen in the direction of the arrow
- FIG. 14 (f) is a cross-sectional view taken along the line FF ′ in FIG. 13 as seen in the direction of the arrow. is there.
- FIG. 15 is a top view illustrating a process of forming a memory groove.
- FIG. 15 is a top view illustrating a process of forming a memory groove.
- FIG. 16 is a cross-sectional view showing a process of forming a memory groove.
- FIG. 16A is a cross-sectional view taken along the line AA ′ in FIG. 15 is a cross-sectional view taken along the line BB ′ in FIG. 15 as seen in the direction of the arrow.
- FIG. 16C is a cross-sectional view taken along the line CC ′ in FIG. 15 as seen in the direction of the arrow.
- 16D is a cross-sectional view taken along the line DD ′ in FIG. 15 as viewed in the direction of the arrow
- FIG. 16E is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 16F is a cross-sectional view taken along the line FF ′ in FIG.
- FIG. 17 is a top view showing a step of implanting phosphorus atoms (P) into the exposed portion of the P-type silicon substrate at the bottom of each memory groove.
- FIG. 18 is a cross-sectional view showing the step of implanting phosphorus atoms (P) into the exposed portion of the P-type silicon substrate at the bottom of each memory trench, and FIG. 18 (a) is taken along line AA ′ in FIG.
- FIG. 18B is a cross-sectional view taken along the line BB ′ in FIG. 17, and
- FIG. 18C is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 18 (d) is a cross-sectional view taken along the line CC ′ in FIG.
- FIG. 18 (d) is a cross-sectional view taken along the line DD ′ in FIG. e) is a cross-sectional view taken along the line EE ′ in FIG. 17 as seen in the direction of the arrow
- FIG. 18 (f) is a cross-sectional view taken along the line FF ′ in FIG. It is sectional drawing.
- FIG. 19 is a top view showing a process of forming Si 3 N 4 portions (side walls) on the left and right side walls of each memory groove.
- FIG. 20 is a cross-sectional view showing a process of forming Si 3 N 4 portions (side walls) on the left and right side walls of each memory trench, and FIG. 20A is cut along AA ′ in FIG.
- FIG. 20B is a sectional view taken along the line BB ′ in FIG. 19, and a sectional view taken along the line BB ′ in FIG. 19, and FIG. 20C is a sectional view taken along the line CC in FIG.
- FIG. 20D is a cross-sectional view taken along the line DD ′ in FIG. 19
- FIG. 20E is a cross-sectional view taken along the line DD ′ in FIG. 19 is a cross-sectional view taken along the line EE ′ as seen in the direction of the arrow
- FIG. 20 (f) is a cross-sectional view taken along the line FF ′ in FIG. 19 as seen in the direction of the arrow. is there.
- FIG. 20D is a cross-sectional view taken along the line DD ′ in FIG. 19
- FIG. 21 is a top view showing a step of implanting phosphorus atoms (P) into a portion where a P-type silicon substrate is exposed between a pair of Si 3 N 4 portions formed in each memory groove.
- FIG. 22 is a cross-sectional view showing a step of implanting phosphorus atoms (P) into a portion where the P-type silicon substrate is exposed between a pair of Si 3 N 4 portions formed in each memory groove, and FIG. ) Is a cross-sectional view taken along the line AA ′ in FIG. 21 as viewed in the direction of the arrow, and FIG. 22B is a cross-sectional view taken along the line BB ′ in FIG. FIG.
- FIG. 22 (c) is a cross-sectional view taken along the line CC ′ in FIG. 21 as seen in the direction of the arrow
- FIG. 22 (d) is a cross-section taken along the line DD ′ in FIG. 22E is a cross-sectional view taken along the line EE ′ in FIG. 21, and a cross-sectional view taken in the direction of the arrow is shown in FIG. 22
- FIG. 22F is a cross-sectional view taken along the line FF ′ in FIG. It is sectional drawing which looked at the cross section cut along along the arrow direction.
- FIG. 23 is a top view showing a step of forming a platinum silicide layer in a portion where the P implantation region is exposed between a pair of Si 3 N 4 portions formed in each memory trench.
- FIG. 24 is a cross-sectional view showing a step of forming a platinum silicide layer in a portion where the P implantation region is exposed between a pair of Si 3 N 4 portions formed in each memory trench
- FIG. 23 is a cross-sectional view taken along the line AA ′ in FIG. 23
- FIG. 24B is a cross-sectional view taken along the line BB ′ in FIG. 24
- (c) is a cross-sectional view taken along the line CC ′ in FIG. 23 as viewed in the direction of the arrow.
- FIG. 24 is a cross-sectional view showing a step of forming a platinum silicide layer in a portion where the P implantation region is exposed between a pair of Si 3 N 4 portions formed in each memory trench
- FIG. 23 is a cross
- FIG. 24 (d) is a cross-sectional view taken along the line DD ′ in FIG. 24E is a cross-sectional view taken along the line EE ′ in FIG. 23, and is a cross-sectional view taken along the line FF ′ in FIG. 23.
- FIG. 24F is a cross-sectional view taken along the line FF ′ in FIG. It is sectional drawing which looked at the cross section which looked at the arrow direction.
- FIG. 25 is a top view showing a process of forming a tantalum oxide layer and a tantalum nitride layer on the entire surface including the side surface and the bottom surface of each memory groove.
- FIG. 26 is a cross-sectional view showing a process of forming a tantalum oxide layer and a tantalum nitride layer on the entire surface including the side surface and the bottom surface of each memory groove, and FIG. 26 (a) is taken along line AA ′ in FIG.
- FIG. 26B is a cross-sectional view taken along the line BB ′ in FIG. 25
- FIG. 26C is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 26D is a cross-sectional view taken along the line CC ′ as viewed in the direction of the arrow.
- FIG. 26D is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 27 is a top view showing a process of removing the tantalum oxide layer and the tantalum nitride layer except for the portion existing inside the memory trench.
- FIG. 28 is a cross-sectional view showing a process of removing the tantalum oxide layer and the tantalum nitride layer except for the portion existing inside the memory trench, and FIG. 28A is taken along line AA ′ in FIG.
- FIG. 28B is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 28C is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 28D is a cross-sectional view taken along the line CC ′ as viewed in the direction of the arrow.
- FIG. 28D is a cross-sectional view taken along the line DD ′ in FIG. e) is a cross-sectional view taken along the line EE ′ in FIG. 27 as seen in the direction of the arrow, and
- FIG. 28 (f) is a cross-sectional view taken along the line FF ′ in FIG. It is sectional drawing.
- FIG. 28D is a cross-sectional view taken along the line CC ′ as viewed in the direction of the arrow.
- FIG. 28D is a cross-sectional view taken along the line DD ′ in FIG. e) is a cross-sectional view taken along the line EE ′ in FIG. 27 as seen in the direction of the arrow
- FIG. 28 (f) is a cross-sectional view
- FIG. 29 is a top view showing a process of forming a tungsten layer in the groove formed inside the tantalum nitride layer and forming a silicon dioxide layer in the recess.
- FIG. 30 is a cross-sectional view showing a process of forming a tungsten layer in the groove formed inside the tantalum nitride layer and forming a silicon dioxide layer in the recess
- FIG. 30B is a cross-sectional view taken along the line BB ′ in FIG. 29, and
- FIG. 30C is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 30D is a cross-sectional view taken along the line CC ′ in FIG. 29, and FIG.
- FIG. 30D is a cross-sectional view taken along the line DD ′ in FIG. 30 (e) is a sectional view taken along the line EE ′ in FIG. 29 as seen in the direction of the arrow, and FIG. 30 (f) is a sectional view taken along the line FF ′ in FIG. 29 in the direction of the arrow.
- FIG. FIG. 31 is a top view showing a process of forming a silicon dioxide layer on the entire surface and further forming a groove for embedding a word line.
- FIG. 32 is a cross-sectional view showing a process of forming a silicon dioxide layer on the entire surface and further forming a groove for embedding a word line, and FIG. 32A is cut along AA ′ in FIG. FIG.
- FIG. 32B is a cross-sectional view taken along the line BB ′ in FIG. 31 and FIG. 32C is a cross-sectional view taken along the line CC in FIG.
- FIG. 32D is a cross-sectional view taken along the line DD ′ in FIG. 31
- FIG. 32E is a cross-sectional view taken along the line DD ′ in FIG. 31 is a cross-sectional view taken along the line EE ′ as viewed in the direction of the arrow
- FIG. 32 (f) is a cross-sectional view taken along the line FF ′ in FIG. is there.
- FIG. 33 is a top view showing a step of forming a hole for embedding the control electrode (gate) of the transistor.
- FIG. 34 is a cross-sectional view showing a step of forming a hole for embedding a control electrode (gate) of a transistor.
- FIG. 34 (a) is a cross section taken along line AA ′ in FIG. 34B is a cross-sectional view taken along the line BB ′ in FIG. 33, and is a cross-sectional view taken along the line BB ′ in FIG. 33.
- FIG. 34C is a cross-sectional view taken along the line CC ′ in FIG.
- FIG. 34D is a cross-sectional view taken along the line DD ′ in FIG. 33
- FIG. 34E is a cross-sectional view taken along the line DD ′ in FIG. FIG.
- FIG. 34F is a cross-sectional view taken along the line FF ′ in FIG. 33, and is a cross-sectional view taken along the line E '.
- FIG. 35 is a top view showing a process of forming a word line and a control electrode (gate) of a transistor.
- FIG. 36 is a cross-sectional view showing a process of forming word lines and transistor control electrodes (gates).
- FIG. 36 (a) is a cross-sectional view taken along line AA 'in FIG.
- FIG. 36B is a cross-sectional view taken along the line BB ′ in FIG. 35 as viewed in the direction of the arrow.
- FIG. 36C is a cross-sectional view taken along the line CC ′ in FIG. FIG.
- FIG. 36D is a cross-sectional view taken along the line DD ′ in FIG. 35
- FIG. 36E is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 36F is a cross-sectional view of the cross section taken along the line FF ′ in FIG. 35 and viewed in the direction of the arrow.
- FIG. 37 is a top view showing a process of forming a trench for burying a source line and a hole for burying a contact.
- FIG. 38 is a cross-sectional view showing a process of forming a trench for burying a source line and a hole for burying a contact.
- FIG. 38 (a) is a cross-sectional view taken along line AA 'in FIG. FIG.
- FIG. 38B is a cross-sectional view taken along the line BB ′ in FIG. 37
- FIG. 38C is a cross-sectional view taken along the line CC ′ in FIG.
- FIG. 38D is a cross-sectional view taken along the line DD ′ in FIG. 37
- FIG. 38E is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 38F is a cross-sectional view taken along the line EE ′ in FIG. 37
- FIG. 38F is a cross-sectional view taken along the line FF ′ in FIG.
- FIG. 39 is a top view showing a process of forming source lines and contacts. 40 is a cross-sectional view showing a process of forming source lines and contacts, and FIG.
- FIG. 40A is a cross-sectional view taken along the line AA ′ in FIG. 39B is a cross-sectional view taken along the line BB ′ in FIG. 39 as viewed in the direction of the arrow.
- FIG. 40C is a cross-sectional view taken along the line CC ′ in FIG. 40 (d) is a cross-sectional view taken along the line DD 'in FIG. 39 as seen in the direction of the arrow, and FIG. 40 (e) is taken along the line EE' in FIG.
- FIG. 40F is a cross-sectional view of the cross section taken along the line FF ′ in FIG. 39 as viewed in the direction of the arrow.
- FIG. 41 is a top view showing a process of forming a bit line and a contact.
- FIG. 42 is a cross-sectional view showing a process of forming a bit line and a contact
- FIG. 42 (a) is a cross-sectional view taken along the line AA ′ in FIG. 41B is a cross-sectional view taken along the line BB ′ in FIG. 41 as viewed in the direction of the arrow
- FIG. 42C is a cross-sectional view taken along the line CC ′ in FIG. 42
- (d) is a cross-sectional view taken along the line DD 'in FIG. 41, as viewed in the direction of the arrow
- FIG. 42 (e) is taken along the line EE' in FIG.
- FIG. 42 (f) is a cross-sectional view taken along the line FF ′ in FIG.
- FIG. 43 is a block diagram showing an example of a circuit configuration of the nonvolatile memory device 100 ′ according to the modification of the first embodiment of the present invention.
- FIG. 44 is a block diagram showing an example of a circuit configuration of the nonvolatile memory device 200 according to Embodiment 2 of the present invention.
- FIG. 45 is a conceptual diagram for simulating a potential drop due to the substrate bias effect.
- FIG. 46 is a diagram showing a result of obtaining a potential drop due to the substrate bias effect by simulation based on the conceptual diagram of FIG.
- FIG. 47 is a schematic diagram of a cross section of the memory cell disclosed in Patent Document 2.
- FIG. 48 is a circuit diagram disclosed in Patent Document 3. In FIG.
- FIG. 1 is a block diagram showing an example of a circuit configuration of the nonvolatile memory device 100 according to the first embodiment of the present invention.
- FIG. 2 is an enlarged view of the memory cell MC portion in FIG. The subscript indicates the row or column number of the corresponding memory block.
- the nonvolatile memory device 100 includes a plurality of word lines WL0 0 , WL1 0 , WL2 0 , WL3 0 , WL1 0 , WL1 extending in parallel with each other in the first direction in the first plane. 1 ,... (Consisting of a first wiring, for example, tungsten: hereinafter simply referred to as “WL”), and in a second plane parallel to the first plane, parallel to each other in the second direction and three-dimensionally intersecting with the first wiring A plurality of source lines SL0 0 , SL1 0 , SL2 0 , SL3 0 , SL0 1 , SL1 1 ,...
- WL word lines
- SL Local wiring made of, for example, copper: hereinafter simply referred to as “SL”) and a word Memory cells MC00 00 , MC01 00 , MC02 00 , MC03 00 , MC10 00 ,... MC33 provided corresponding to each of the solid intersections of the line WL and the source line SL 00 ,... MC32 mn , MC33 mn (hereinafter simply referred to as “MC”).
- MC word Memory cells
- Each of the memory cells MC includes one transistor TR (for example, an FET transistor) and one resistance change element RR (for example, a ReRAM element).
- Each of the transistors TR includes a first main terminal T1 (source / drain), a second main terminal T2 (source / drain), and a control terminal T3 (gate).
- Each of the resistance variable elements RR includes a first electrode E1 (for example, a lower electrode made of platinum or platinum silicide), a second electrode E2 (for example, an upper electrode made of tantalum nitride), a first electrode E1, and a second electrode E2.
- It includes a resistance change layer VR for example, an oxide of a transition metal such as Ta, Ni, Ti, Hf, Zr, etc.
- It preferably includes a tantalum oxide, and more preferably includes a tantalum oxide. ).
- a first main terminal T1 of one memory cell MC and a second main terminal T2 of the other memory cell MC included in two adjacent memory cells MC are By being connected, the main terminals of the plurality of memory cells are sequentially connected in series and serial paths SP0 00 , SP1 00 , SP2 00 , SP3 00 , SP0 01 ,. "SP") is formed.
- the control terminal T3 is connected to the word line WL corresponding to that memory cell MC.
- the second electrode E2 is connected to the source line SL corresponding to the memory cell MC.
- the second electrode E2 may be a part of the source line SL corresponding to the memory cell MC.
- the first electrode E1 is connected to the series path SP corresponding to the memory cell MC.
- the first electrode E1 may be a part of the series path SP corresponding to the memory cell MC.
- one resistance variable element is formed for each transistor. That is, two adjacent resistance change elements share one transistor in the first electrode E1, and the second electrode E2 is connected to the wiring without being connected to the transistor.
- the current passed through the selected memory cell flows through the series path SP and does not flow between both electrodes of the unselected memory cell.
- the nonvolatile memory device 100 further includes a plurality of bit lines BL0, BL1,... (Third wiring, for example, made of copper: hereinafter simply referred to as “BL”) extending in parallel with each other in the first direction.
- the plurality of memory cells MC arranged in the direction constitute a plurality of memory blocks MB by a predetermined number of memory cells MC arranged in series, and the series path SP extends in the second direction for each memory block MB. It is connected to the bit line BL via a wiring CL (for example, made of platinum silicide: hereinafter simply referred to as “CL”).
- CL for example, made of platinum silicide
- the first main terminal T1 and the second main terminal T2 each have a silicide layer, and this silicide layer constitutes the first electrode E1.
- This silicide layer is preferably made of platinum silicide.
- the silicide formed on the silicon substrate is used for the electrode of the resistance variable element, the element size can be further reduced.
- the silicide layer is preferably made of platinum silicide.
- the source lines SL are connected to the column decoder 102, respectively.
- the word line WL and the bit line BL are connected to the row decoder 104, respectively.
- the memory cells MC, word lines WL, source lines SL, bit lines BL, contact lines CL, column decoders 102, and row decoders 104 constitute one memory cell array 106 as a whole.
- the first (first column) memory cells MC00 00 , MC10 00 , MC20 00 , MC30 00 , MC00 10 ,... From the left side belonging to the memory cell block MB x0 in the first column.
- the nonvolatile memory device 100 further receives an address signal AD from the outside and sends it to the memory cell array 106, a control circuit 110 that receives the control signal CTL from the outside and sends it to the memory cell array 106, and a predetermined voltage Output from a power input circuit 112 that outputs (a write voltage such as a low resistance voltage or a high resistance voltage or a read voltage), a data input / output circuit 114 that transfers data to / from the outside, and a data input / output circuit.
- a write circuit 116 for inputting a voltage output from the power supply circuit 112 to the memory cell array based on the write data to be written, and a sense amplifier 120 are provided.
- the sense amplifier 120 detects the amount of current flowing through the selected bit line, and when this amount of current is the amount of current corresponding to the case where the memory cell is in the high resistance state, the data is “1”, and the memory cell has a low resistance. The current amount corresponding to the state is determined as data “0”.
- the power supply circuit 112 generates a voltage to be applied when the resistance of the memory cell MC is reduced (the resistance variable element RR included in the memory cell MC is in a low resistance state). And a high resistance voltage generation circuit 124 for generating a voltage to be applied when the resistance of the memory cell MC is increased (the resistance variable element RR included in the memory cell MC is set to a high resistance state). ing.
- FIG. 3 is a diagram showing one memory block
- FIG. 3 (a) is a top view of the memory block
- FIG. 3 (b) is an equivalent circuit diagram of FIG. 3 (a).
- FIG. 3B is an enlarged view of the memory block MB extracted in FIG.
- the word lines WL extend in parallel to each other in the first direction (left-right direction in the drawing) in the first plane
- source lines SL second wiring
- the bit line BL third wiring
- the contact wiring CL fourth wiring
- a memory cell MC and a first main terminal T1 and a second main terminal T2 of a transistor TR are provided at each of the solid intersections of the word line WL and the source line SL.
- a control terminal T3 of the transistor TR is provided in a portion of the word line WL that does not overlap with the source line SL.
- a contact C1 (a connection portion between the source line SL and the second electrode E2) is provided below the solid intersection of the bit line BL and the source line SL.
- the second electrode E2 is formed so as to extend in the second direction, and functions as an upper electrode of the plurality of resistance variable elements RR. Therefore, in the equivalent circuit diagram (FIG. 3B), it seems that the second electrode E2 is connected to the source line SL for each memory cell, but actually the second electrode E2 is connected to the source line SL for each memory cell block. However, the circuit is equivalent to FIG.
- a contact C2 (a connecting portion between the bit line BL and the contact wiring CL) is provided at a solid intersection of the bit line BL and the contact wiring CL.
- FIG. 4A is a cross sectional view taken along the line AA ′ in FIG. 3
- FIG. 3 is a cross-sectional view taken along line BB ′ in FIG. 3
- FIG. 4C is a cross-sectional view taken along line CC ′ in FIG. 3
- FIG. 4D is a cross-sectional view taken along line D-- in FIG.
- FIG. 4E is a cross-sectional view taken along line EE ′ of FIG. 3
- FIG. 4F is a cross-sectional view taken along line FF ′ of FIG. FIG.
- FIG. 4A is a cross sectional view taken along the line AA ′ in FIG. 3
- FIG. 3 is a cross-sectional view taken along line BB ′ in FIG. 3
- FIG. 4C is a cross-sectional view taken along line CC ′ in FIG. 3
- FIG. 4D is a cross-sectional view taken along line D-- in FIG.
- FIG. 4E is a cross-
- the direction in which the source line SL extends is the front-rear direction
- the thickness direction of the substrate is the up-down direction
- the direction in which the word line WL extends is the left-right direction.
- FIG. 4 it is shown that the same mesh pattern is composed of substantially the same material in principle. However, the detailed composition and components may be different even in the portions indicated by the same mesh pattern.
- a plurality of silicon dioxide layers 132 are formed on the P-type silicon substrate layer 130 so as to extend in the left-right direction at a predetermined interval.
- the left end of the silicon dioxide layer 132 is continuous in the front-rear direction.
- the portion extending from side to side in the silicon dioxide layer 132 constitutes an STI [Shallow Trench Insulator] region.
- the size of the STI region is, for example, a width of 0.18 ⁇ m and a depth of 300 nm.
- a plurality of grooves (hereinafter referred to as “memory grooves”.
- the number of memory grooves in FIG. 4 is 5) is formed so as to extend through the upper half of the silicon dioxide layer 132 in the front-rear direction.
- the size of the memory groove is, for example, a width of 0.18 ⁇ m and a depth of 550 nm (STI + dummy gate height).
- Si 3 N 4 portions 138 (side walls) are formed on the left and right side wall portions of the memory groove.
- a tantalum oxide layer 140 (resistance change layer) and a tantalum nitride layer 142 (upper electrode layer) are formed in this order so as to cover the surface of the Si 3 N 4 portion 138 and the bottom surface of the memory groove.
- the thickness of the bottom of the tantalum oxide layer 140 is, for example, 30 nm.
- a tungsten layer 144 (embedded conductor layer) is formed so as to fill a groove formed inside the tantalum nitride layer 142.
- the Si 3 N 4 portion 138, the tantalum oxide layer 140, the tantalum nitride layer 142, and the tungsten layer 144 fill the memory groove as a whole, the upper end surface forms a recess, and the recess is filled with the silicon dioxide layer 148. ing.
- the titanium / titanium nitride layer 149 is filled in the recess.
- the buried conductor layer may be formed of copper or aluminum.
- a tungsten layer 152 and a titanium / titanium nitride layer 150 (adhesion layer) constituting the word line WL are formed to extend in the left-right direction.
- the size of the tungsten layer 152 is, for example, a width of 0.18 ⁇ m and a depth of 300 nm.
- the tungsten layer 152 and the titanium / titanium nitride layer 150 extend downward and are in contact with the P-type silicon substrate layer 130 through the silicon dioxide layer 158.
- the thickness of the silicon dioxide layer 158 is, for example, 10 nm.
- a portion where the tungsten layer 152 is connected to the P-type silicon substrate layer 130 with the silicon dioxide layer 158 interposed therebetween functions as a control terminal T3 (gate) of the transistor TR.
- the size of the control terminal T3 is, for example, 0.18 ⁇ m ⁇ 0.18 ⁇ m.
- a P implantation region 134 (source / drain region) is formed at a connection portion between the P-type silicon substrate layer 130 and the memory groove.
- a platinum silicide layer 136 is formed on the P implantation region 134.
- the P implantation region 134 and the platinum silicide layer 136 are formed inside the P-type silicon substrate layer 130.
- the P implantation region 134 may be an As implantation region (using arsenic atoms [As] instead of phosphorus atoms [P]).
- the rightmost one (hereinafter referred to as contact wiring groove) has no silicon dioxide layer 132 formed in the STI region, and the memory groove and the P-type silicon substrate layer 130 are connected. .
- a P implantation region 134 and a platinum silicide layer 136 are formed on the bottom surface of the contact wiring groove so as to be continuous (extend in the front-rear direction).
- the platinum silicide layer 136 connected to the contact wiring trench constitutes the contact wiring CL.
- the platinum silicide layer 136 connected to the memory trench other than the contact wiring trench constitutes a lower electrode layer (first electrode E1).
- a portion of the tantalum nitride layer 142 corresponding to the lower electrode layer functions as the second electrode E2.
- a portion of the tantalum oxide layer 140 sandwiched between the lower electrode layer and the upper electrode layer functions as the resistance change layer VR.
- the P implantation region 134 and the platinum silicide layer 136 function as a first main terminal T1 (source / drain) and a second main terminal T2 (source / drain) of the transistor TR.
- the platinum silicide layer 136 that constitutes the lower electrode of the resistance variable element RR simultaneously constitutes a part of the series path SP.
- the P injection region 134 which is a component of the first main terminal T1 and the second main terminal T2 of the transistor TR also forms part of the series path SP.
- a plurality of copper layers 154 constituting the source line SL are formed to extend in the front-rear direction above the tungsten layer 152 with the silicon dioxide layer 156 (interlayer insulating layer) interposed therebetween.
- the copper layer 154 is connected to the titanium / titanium nitride layer 149 (adhesion layer), and the copper layer 154 of the connection portion constitutes a contact 153 (contact C1 in FIG. 3).
- a titanium / titanium nitride layer may be formed as an adhesion layer also at a boundary portion between the copper layer 154 and the silicon dioxide layer 156.
- a copper layer 162 constituting the bit line BL is formed so as to extend in the left-right direction above the copper layer 154 with the silicon dioxide layer 156 (interlayer insulating layer) interposed therebetween.
- the copper layer 162 is connected to the platinum silicide layer 136, and the copper layer 162 at the connection portion constitutes a contact 161 (contact C ⁇ b> 2 in FIG. 3). That is, in this portion, the tantalum oxide layer 140, the tantalum nitride layer 142, and the tungsten layer 144 are removed, and the bit line BL and the platinum silicide layer 136 (contact wiring CL) are short-circuited via the contact 161.
- a titanium / titanium nitride layer may be formed as an adhesion layer also at a boundary portion between the copper layer 162 and the silicon dioxide layer 156.
- a polysilicon layer 160 derived from the manufacturing process is formed in the lower half between the memory grooves.
- the thickness of the polysilicon layer 160 is, for example, 250 nm.
- an Si 3 N 4 layer 146 derived from the manufacturing process is formed on the polysilicon layer 160 and the silicon dioxide layer 132.
- the thickness of the Si 3 N 4 layer 146 is, for example, 50 nm.
- FIG. 5 is a diagram illustrating an example of characteristics (relationship between voltage and resistance value) of the resistance variable element included in the nonvolatile memory device according to Embodiment 1 of the present invention.
- the lower electrode is platinum (thickness 50 nm)
- the resistance change layer is tantalum oxide (when expressed as TaOx, 0 ⁇ x ⁇ 2.5)
- the upper electrode is tantalum nitride (thickness 100 nm)
- Tantalum oxide was formed by sputtering (300 ° C.).
- An electrical pulse was applied to the obtained variable resistance element while gradually changing the voltage with a pulse width of 100 nsec.
- the resistance value of the resistance variable element was obtained by applying a voltage of 50 mV and measuring the current each time it was applied.
- the plot in the figure shows the voltage (voltage generated between the upper electrode and the lower electrode) actually applied to the resistance variable element.
- the polarity of the voltage is indicated by the potential of the lower electrode with respect to the upper electrode. That is, the case where the potential of the lower electrode was higher than that of the upper electrode was regarded as positive.
- FIG. 6 is a timing chart showing an operation example of the nonvolatile memory device according to Embodiment 1 of the present invention.
- FIG. 6A shows a case where “0” is written in the memory cell MC00 00 (resistance change element RR).
- FIG. 6B shows a case where “1” is written in the memory cell MC00 00 (when the resistance variable element RR is increased in resistance), and
- FIG. 6C shows a case where the memory cell MC00 00 has a low resistance.
- the case where the written data is read is shown.
- the case where the resistance variable element RR is in the low resistance state (LR) is associated with the data “0”
- the case where the resistance variable element RR is in the high resistance state (HR) is the data “1”.
- LR low resistance state
- HR high resistance state
- V1 is a voltage output from the low resistance voltage generation circuit 122.
- V1 + 1.5 V (a positive voltage having an absolute value larger than ⁇ 0.8 V, which is the threshold for reducing resistance in FIG. 5).
- V2 is a voltage output from the high resistance voltage generation circuit 124.
- V2 + 1.5 V (a positive voltage having a larger absolute value than +1.2 V, which is the threshold value for increasing resistance in FIG. 5).
- Vread is a read voltage generated by the sense amplifier 120.
- Vread + 0.5V (from the low resistance state disturb boundary voltage in FIG. 5 [the upper limit voltage at which the resistance value of the resistance variable element in the low resistance state does not change] Can also be a positive voltage having a large absolute value).
- the power supply voltage supplied to the nonvolatile memory element 100 from the outside corresponds to the power supply voltage supplied to the nonvolatile memory element 100 from the outside, and is, for example, + 4.5V.
- ⁇ V1 ( ⁇ 1.5 V) is applied to the first electrode E1 (lower electrode) with respect to the second electrode E2 (upper electrode).
- a voltage is applied.
- the resistance variable element RR changes from the high resistance state to the low resistance state.
- the voltage of the selected word line WL00 is set to 0V, and the data “0” write operation is completed.
- the voltage of the second electrode E2 to the first electrode E1 (the lower electrode) as a reference (upper electrode) + V2 (+ 1.5V) is Applied.
- the resistance variable element RR changes from the low resistance state to the high resistance state.
- the voltage of the selected word line WL00 is set to 0V, and the data “1” write operation is completed.
- the address input circuit 108 receives an address signal from an external circuit (not shown), outputs a row address signal to the column decoder 102 based on this address signal, and outputs a column address signal to the row decoder 104.
- the address signal is a signal indicating an address of a specific memory cell selected from among a plurality of memory cells.
- control circuit 110 In the data write cycle, the control circuit 110 outputs a write signal instructing application of a write voltage to the write circuit 116 in accordance with the input data Din input to the data input / output circuit 114.
- the column decoder 102 receives the row address signal output from the address input circuit 108, and in response to the row address signal, the row decoder 104 applies a predetermined word line to a selected word line from among the plurality of word lines. Apply voltage. Similarly, the column decoder 102 receives the row address signal output from the address input circuit 108, and in response to the row address signal, the column decoder 102 applies the selected source line among the plurality of source lines. Then, a predetermined voltage is applied.
- the row decoder 104 receives the column address signal output from the address input circuit 108, selects one of a plurality of bit lines in accordance with the column address signal, and selects the selected bit line. Then, a writing voltage or a reading voltage is applied.
- the write power source 112 includes an LR power source 122 for reducing resistance and an HR power source 124 for increasing resistance, and outputs thereof are input to the row decoder 104 and the write circuit 116, respectively.
- the resistance variable element RR is in a low resistance state (data is “0”) or in a high resistance state. (Whether the data is “1”). Thereafter, the voltage of the selected word line WL00 is set to 0V, and the data read operation is completed.
- FIGS. 7 to 42 are views showing steps for manufacturing the nonvolatile memory device according to the first embodiment of the present invention.
- processes other than those shown in FIGS. 7 to 42 are required. However, since these processes can be performed using known methods, description thereof is omitted.
- FIG. 7 and 8 are a top view and a cross-sectional view showing a process of forming a polysilicon layer on a P-type silicon substrate, respectively.
- 8A is a cross-sectional view taken along the line AA ′ in FIG. 7 as viewed in the direction of the arrow.
- FIG. 8B is a cross-sectional view taken along the line BB ′ in FIG. 8C is a cross-sectional view taken along the line CC ′ in FIG. 7, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 8D is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 8E is a cross-sectional view taken along the line EE ′ in FIG. 7, and
- FIG. 8F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- step S1 polysilicon is deposited on the P-type silicon substrate made of the P-type silicon layer 130 by CVD (conditions are deposited by way of example). Then, a polysilicon layer 160 is formed, and the dummy gate is preferably formed at a thickness optimized for a process such as dry etching characteristics.
- FIGS. 9 and 10 are a top view and a cross-sectional view showing a step of forming a trench for forming an STI by etching a P-type silicon substrate and a polysilicon layer, respectively.
- 10A is a cross-sectional view taken along the line AA ′ in FIG. 9 as viewed in the direction of the arrow
- FIG. 10B is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 10C is a cross-sectional view taken along the line CC ′ in FIG. 9, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 10D is a cross-sectional view taken along the line DD ′ in FIG. FIG.
- FIG. 10E is a cross-sectional view taken along the line EE ′ in FIG. 9, and FIG. 10F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- a desired groove is formed by a patterning process using a mask.
- FIGS. 11 and 12 are a top view and a cross-sectional view, respectively, showing a process of forming STI by embedding silicon dioxide in the groove.
- 12A is a cross-sectional view taken along the line AA ′ in FIG. 11 as viewed in the direction of the arrow
- FIG. 12B is a cross-sectional view taken along the line BB ′ in FIG. 12C is a cross-sectional view taken along the line CC ′ in FIG. 11, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 12D is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 12E is a cross-sectional view taken along the line EE ′ in FIG. 11, and
- FIG. 12F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- silicon dioxide (SiO 2 ) (HDP-NSG film) is subjected to HDP-CVD (600 nm) so as to fill the groove 163 formed in step S2.
- the silicon dioxide layer 130 is formed by removing the silicon dioxide until reaching the upper end surface of the polysilicon layer 160 by CMP.
- FIG. 13 and 14 are a top view and a cross-sectional view showing a process of forming a Si 3 N 4 layer so as to cover the silicon dioxide layer and the polysilicon layer, respectively.
- 14A is a cross-sectional view taken along the line AA ′ in FIG. 13 as viewed in the direction of the arrow
- FIG. 14B is a cross-sectional view taken along the line BB ′ in FIG. 14C is a cross-sectional view taken along the line CC ′ in FIG. 13, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 14D is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 14E is a cross-sectional view taken along the line EE ′ in FIG. 13
- FIG. 14F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction
- Si 3 N 4 is deposited on the entire surface by the CVD method, so that the Si 3 N 4 layer 146 is formed. It is formed.
- FIG. 15 and FIG. 16 are a top view and a cross-sectional view showing a process of forming a memory groove, respectively.
- 16A is a cross-sectional view taken along the line AA ′ in FIG. 15 as viewed in the direction of the arrow.
- FIG. 16B is a cross-sectional view taken along the line BB ′ in FIG. 16C is a cross-sectional view taken along the line CC ′ in FIG. 15, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 16D is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 16E is a cross-sectional view taken along the line EE ′ in FIG. 15, and
- FIG. 16F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- the Si 3 N 4 layer 146, the polysilicon layer 160, and the silicon dioxide layer 132 are formed at predetermined widths and intervals so as to extend in the vertical direction (second direction) in FIG.
- the memory groove 164 is formed.
- the bottom surface of the memory groove is flat, and its position is adjusted to coincide with the bottom surface of the polysilicon layer 160.
- the rightmost of the five memory grooves 164 is the contact wiring groove 166.
- FIGS. 17 and 18 are a top view and a cross-sectional view showing a step of implanting phosphorus atoms (P) into the exposed portions of the P-type silicon substrate at the bottom of each memory groove, respectively.
- 18A is a cross-sectional view taken along the line AA ′ in FIG. 17 as viewed in the direction of the arrow
- FIG. 18B is a cross-sectional view taken along the line BB ′ in FIG. 18
- (c) is a cross-sectional view taken along the line CC ′ in FIG. 17, and is a cross-sectional view taken in the direction of the arrow
- FIG. 18 (d) is along the line DD ′ in FIG. FIG.
- FIG. 18E is a cross-sectional view taken along the line EE ′ in FIG. 17, and FIG. 18F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- the bottom surface of the memory groove 164 formed in step S5 is formed with low energy by ion implantation.
- Phosphorus atoms (P) are implanted, and a P implantation region 134 is formed by rapid annealing.
- phosphorus atoms are implanted only into the portion where the P-type silicon substrate layer 130 is exposed, and a P implantation region 134 is formed.
- phosphorus atoms are not implanted into the exposed portion of the silicon dioxide layer 132, and no P implantation region 134 is formed.
- the P implantation region 134 is formed over the entire bottom surface of the contact wiring trench 166.
- P implantation regions 134 are formed in island shapes at predetermined intervals on the bottom surfaces of the other memory grooves 164 (see FIG. 17).
- Arsenic (As) atoms may be implanted instead of phosphorus atoms.
- FIG. 19 and 20 are a top view and a cross-sectional view showing a process of forming Si 3 N 4 portions (side walls) on the left and right side walls of each memory groove, respectively.
- 20A is a cross-sectional view taken along the line AA ′ in FIG. 19 as viewed in the direction of the arrow
- FIG. 20B is a cross-sectional view taken along the line BB ′ in FIG.
- 20C is a cross-sectional view taken along the line CC ′ in FIG. 19, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 20D is a cross-sectional view taken along the line DD ′ in FIG.
- FIG. 20E is a cross-sectional view taken along the line EE ′ in FIG. 19
- FIG. 20F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the
- Si 3 N 4 is deposited to a thickness of 70 nm on the entire surface by the CVD method, and other than the side surface of the memory groove by dry etching.
- the Si 3 N 4 portion 138 is formed by removing the Si 3 N 4 adhering to the surface.
- FIGS. 21 and 22 are a top view and a cross-sectional view showing a step of implanting phosphorus atoms (P) into a portion where the P-type silicon substrate is exposed between a pair of Si 3 N 4 portions formed in each memory groove, respectively.
- FIG. 22A is a cross-sectional view taken along the line AA ′ in FIG. 21 as viewed in the direction of the arrow
- FIG. 22B is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 22C is a cross-sectional view taken along the line CC ′ in FIG. 21, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 22D is a cross-sectional view taken along line DD ′ in FIG. FIG.
- FIG. 22E is a cross-sectional view taken along the line EE ′ in FIG. 21, and FIG. 22F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- step S8 the step is performed by step S7 by ion implantation. Between the Si 3 N 4 portions (sidewalls) thus formed, phosphorus atoms (P) are implanted with low energy, and further, a P implantation region 134 is formed deeper by high-speed annealing. As in step S6, phosphorus atoms are not implanted into the portion where the silicon dioxide layer 132 is exposed, and the P implantation region 134 is not formed.
- FIG. 23 and 24 are a top view and a cross-sectional view showing a step of forming a platinum silicide layer in a portion where the P implantation region is exposed between a pair of Si 3 N 4 portions formed in each memory trench, respectively.
- . 24A is a cross-sectional view taken along the line AA ′ in FIG. 23 as viewed in the direction of the arrow.
- FIG. 24D is a cross-sectional view taken along line DD ′ in FIG. FIG.
- FIG. 24E is a cross-sectional view taken along the line EE ′ in FIG. 23, and FIG. 24F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- step S9 In the step of forming a platinum silicide layer in a portion where the P implantation region is exposed between a pair of Si 3 N 4 portions formed in each memory groove (step S9), first, platinum is formed by sputtering (condition is 5 nm, for example). Deposited on the bottom surface of the memory groove. Next, platinum silicide is generated at the boundary portion between the P implantation region 134 and the deposited platinum layer by annealing (the condition is, for example, 500 ° C., 10 minutes). Thereby, a platinum silicide layer 136 is formed. Excess platinum layer is removed by standard processes.
- 25 and 26 are a top view and a cross-sectional view showing a process of forming a tantalum oxide layer and a tantalum nitride layer on the entire surface including the side surface and the bottom surface of each memory groove, respectively.
- 26A is a cross-sectional view taken along the line AA ′ in FIG. 25 as viewed in the direction of the arrow
- FIG. 26B is a cross-sectional view taken along the line BB ′ in FIG.
- 26C is a cross-sectional view taken along the line CC ′ in FIG. 25, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 26D is a cross-sectional view taken along the line DD ′ in FIG. FIG.
- FIG. 26 (e) is a cross-sectional view taken along the line EE ′ in FIG. 25, and FIG. 26 (f) is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- oxygen can be increased by increasing the oxygen flow rate during film formation in the sputtering (eg, reactive sputtering method).
- the tantalum oxide layer 140 can be formed by depositing tantalum oxide under the conditions of argon 34 sccm, oxygen 24 sccm, power 1.6 kW, and oxygen content of about 72 atm%.
- tantalum nitride is deposited by so-called reactive sputtering, in which a tantalum target is sputtered in an argon and nitrogen gas atmosphere to form a tantalum nitride layer 142.
- the thickness of the tantalum oxide layer is determined so as to ensure an appropriate thickness (for example, 3 nm) of the sidewall portion in consideration of the step coverage (ratio of the size of the sidewall portion to the planar portion). The That is, when the step coverage is 10%, the tantalum oxide is deposited so that the thickness of the planar portion (including the bottom surface of the memory groove) is 30 nm. At this time, the thickness of the tantalum oxide layer 140 on the side wall is about 3 nm.
- FIG. 27 and FIG. 28 are a top view and a cross-sectional view, respectively, showing a process of removing the tantalum oxide layer and the tantalum nitride layer except for the portion existing inside the memory trench.
- 28A is a cross-sectional view taken along the line AA ′ in FIG. 27 as viewed in the direction of the arrow
- FIG. 28B is a cross-sectional view taken along the line BB ′ in FIG.
- 28C is a cross-sectional view taken along the line CC ′ in FIG. 27, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 28D is a cross-sectional view along DD ′ in FIG. FIG.
- FIG. 28E is a cross-sectional view taken along the line EE ′ in FIG. 27, and FIG. 28F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- the tantalum oxide layer 140 except for the portion existing inside the memory trench is formed by CMP.
- the tantalum nitride layer 142 is removed.
- the upper end surfaces of the tantalum oxide layer 140 and the tantalum nitride layer 142 are adjusted to be lower than the upper end surfaces of the Si 3 N 4 layer 146 by increasing the CMP polishing pressure or extending the polishing time. . Note that this can be performed not only by adjusting the CMP conditions but also by etch back.
- FIGS. 29 and 30 are a top view and a cross-sectional view showing a process of forming a tungsten layer in the groove formed inside the tantalum nitride layer and forming a silicon dioxide layer in the recess, respectively.
- 30A is a cross-sectional view taken along the line AA ′ in FIG. 29 as seen in the direction of the arrow
- FIG. 30B is a cross-sectional view taken along the line BB ′ in FIG.
- 30C is a cross-sectional view taken along the line CC ′ in FIG. 29, and is a cross-sectional view taken in the direction of the arrow
- FIG. 30D is a cross-sectional view taken along the line DD ′ in FIG. FIG.
- FIG. 30E is a cross-sectional view taken along the line EE ′ in FIG. 29, and FIG. 30F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- the groove formed inside the tantalum nitride layer 142 and extending in the front-rear direction is filled.
- the tungsten layer 144 is formed. This is done by CVD and CMP.
- a silicon dioxide layer 148 is formed by filling the recess formed by the Si 3 N 4 portion 138 (sidewall), the tantalum oxide layer 140, the tantalum nitride layer 142, and the tungsten layer 144 with silicon dioxide. The This is performed by forming TEOS by CVD (for example, 50 nm) and by CMP.
- FIGS. 31 and 32 are a top view and a cross-sectional view showing a process of forming a silicon dioxide layer on the entire surface and further forming a groove for embedding a word line, respectively.
- 32A is a cross-sectional view taken along the line AA ′ in FIG. 31 as viewed in the direction of the arrow
- FIG. 32B is a cross-sectional view taken along the line BB ′ in FIG. 32
- (c) is a cross-sectional view taken along the line CC 'in FIG. 31, and is a cross-sectional view taken in the direction of the arrow.
- FIG. 32 (d) is along the line DD' in FIG.
- FIG. 32E is a cross-sectional view taken along the line EE ′ in FIG. 31
- FIG. 32F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the
- step S13 In the step of forming a silicon dioxide layer on the entire surface and further forming a groove for embedding the word line WL (step S13), after depositing TEOS by CVD with silicon dioxide, a part of it is etched by using a mask. By removing, a trench 168 for embedding the word line WL is formed, and the Si 3 N 4 layer 146 where the control electrode T3 (gate) of the transistor is formed is exposed (see FIG. 31).
- FIG. 33 and 34 are a top view and a cross-sectional view, respectively, showing a process for forming a hole for embedding a control electrode (gate) of a transistor.
- 34A is a cross-sectional view taken along the line AA ′ in FIG. 33 as viewed in the direction of the arrow
- FIG. 34B is a cross-sectional view taken along the line BB ′ in FIG.
- FIG. 34C is a cross-sectional view taken along the line CC ′ in FIG. 33, and is a cross-sectional view taken in the direction of the arrow in FIG. 33.
- FIG. FIG. 34E is a cross-sectional view taken along the line EE ′ in FIG. 33
- FIG. 34F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- a portion of the Si 3 N 4 layer 146 where the control electrode T3 (gate) of the transistor is formed by dry etching using a mask is formed. Remove.
- the polysilicon layer 160 is soluble in an alkaline solution such as TMAH, but chemical dry etching of CF 4 + O 2 may be used. Thereby, a hole 170 for embedding the control electrode (gate) of the transistor is formed.
- FIG. 35 and FIG. 36 are a top view and a cross-sectional view showing a step of forming a word line and a control electrode (gate) of a transistor, respectively.
- 36A is a cross-sectional view taken along the line AA ′ in FIG. 35 as viewed in the direction of the arrow
- FIG. 36B is a cross-sectional view taken along the line BB ′ in FIG.
- 36C is a cross-sectional view taken along the line CC ′ in FIG. 35, and is a cross-sectional view taken in the direction of the arrow
- FIG. 36D is a cross-sectional view taken along line DD ′ in FIG.
- FIG. 36E is a cross-sectional view taken along the line EE ′ in FIG. 35
- FIG. 36F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an
- a titanium / titanium nitride layer 150 (adhesion layer) is first formed by sputtering, and then a tungsten layer 152 (word line) is formed by plating.
- WL and control electrode T3) are formed.
- FIG. 37 and 38 are a top view and a cross-sectional view showing a process of forming a groove for burying the source line and a hole for burying the contact, respectively.
- FIG. 38A is a cross-sectional view taken along the line AA ′ in FIG. 37 as viewed in the direction of the arrow
- FIG. 38B is a cross-sectional view taken along the line BB ′ in FIG. 38
- (c) is a cross-sectional view taken along the line CC ′ in FIG. 37, and is a cross-sectional view taken in the direction of the arrow
- FIG. 38 (d) is along the line DD ′ in FIG.
- FIG. 38E is a cross-sectional view taken along the line EE ′ in FIG. 37
- FIG. 38F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of
- step S16 silicon dioxide was deposited by a thermal oxidation method (condition is, for example, 10 nm), and then a mask was used. By removing a part thereof by etching, a groove 172 for embedding the source line SL and a hole 174 for embedding the contact C1 are formed.
- FIG. 39 and 40 are a top view and a cross-sectional view, respectively, showing a process for forming a source line and a contact.
- 40A is a cross-sectional view taken along the line AA ′ in FIG. 39 as viewed in the direction of the arrow.
- FIG. 40B is a cross-sectional view taken along the line BB ′ in FIG. 40 (c) is a cross-sectional view taken along the line CC ′ in FIG. 39, and is a cross-sectional view taken in the direction of the arrow
- FIG. 40 (d) is along the line DD ′ in FIG.
- FIG. 40E is a cross-sectional view taken along the line EE ′ in FIG. 39
- FIG. 40F is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- step S17 copper is buried in the groove 172 and the hole 174 formed in step S16 by a damascene process, and excess copper is removed by CMP. Thereby, the copper layer 154 and the contact 153 (contact C1 in FIG. 3) are formed.
- 41 and 42 are a top view and a cross-sectional view showing a process of forming a bit line and a contact, respectively.
- 42A is a cross-sectional view taken along the line AA ′ in FIG. 41 as viewed in the direction of the arrow.
- FIG. 42B is a cross-sectional view taken along the line BB ′ in FIG. 42 (c) is a cross-sectional view taken along the line CC ′ in FIG. 41, and is a cross-sectional view taken in the direction of the arrow
- FIG. 42 (d) is along the line DD ′ in FIG.
- FIG. 42 (e) is a cross-sectional view taken along the line EE ′ in FIG. 41
- FIG. 42 (f) is a cross-sectional view taken along the line EE ′ in FIG.
- FIG. 6 is a cross-sectional view of a cross section cut along ⁇ F ′ as seen in the direction of an arrow.
- step S18 silicon dioxide is deposited on the front surface by TEOS so as to cover the copper layer 154 and the contact 153, and a part thereof is etched by using a mask. By removing, a groove for embedding the bit line BL and a hole for embedding the contact C2 are formed. Copper is buried in the grooves and holes by a damascene process, and excess copper is removed by CMP. Thereby, the copper layer 162 and the contact 161 (contact C2 in FIG. 3) are formed.
- FIG. 42 is the same as FIG. 4.
- FIG. 43 is a block diagram showing an example of a circuit configuration of the nonvolatile memory device 100 ′ according to the modification of the first embodiment of the present invention. As shown in FIG. 43, both ends of the series path may be connected to a bit line (third wiring) for each memory block.
- FIGS. 3 and 4 Such an arrangement, in FIGS. 3 and 4, by adding one of the contact wire CL in the left SL 0 0, is obtained by connecting the bit line BL0 via the contact C2 this.
- the configuration of the contact wiring to be added can be the same as the contact wiring of the first embodiment. Details of the specific configuration and manufacturing method will be omitted because they will be apparent to those skilled in the art from the above description.
- the embodiment is the same as the embodiment shown in FIG. 1 except for the connection relationship between the series path SP and the bit line BL. Therefore, elements common to FIGS. 1 and 43 are denoted by the same reference numerals and names, and description thereof is omitted.
- FIG. 44 is a block diagram showing an example of a circuit configuration of the nonvolatile memory device according to Embodiment 2 of the present invention.
- the nonvolatile memory device 200 includes a power supply circuit 113 for applying a voltage to the resistance variable element included in each memory cell.
- the power supply circuit 113 corresponds to the selected memory cell.
- the output voltage is changed according to the number of transistors TR included in the series path SP from the connection portion between the series path SP and the corresponding bit line (third wiring) to the first electrode E1 of the memory cell MC. It is configured.
- the nonvolatile memory device 200 is the same as the nonvolatile memory device 100 of FIG. 1 except that the power supply circuit 112 is the power supply circuit 113 and the high resistance voltage generation circuit 124 is the first high resistance voltage generation circuit 125. And the second high resistance voltage generation circuit 126, the third high resistance voltage generation circuit 127, and the fourth high resistance voltage generation circuit 128, and the other configuration is the same as that of the nonvolatile memory device 100. is there. Therefore, elements common to FIG. 1 and FIG. 44 are denoted by the same reference numerals and names, and description thereof is omitted.
- the first high resistance voltage generation circuit 125 applies a voltage V2 0 (first high resistance voltage) to be applied to the selected bit line BL when increasing the resistance of the memory cell MC located in the first column from the left of the memory block. Is output.
- V2 0 first high resistance voltage
- the number of transistors h set in the portion connecting the first electrode E1 and the bit line BL of the resistance variable element RR included in the memory cell is four.
- the second high resistance voltage generation circuit 126 is configured to increase the resistance of the memory cell MC located in the second column from the left of the memory block, by applying a voltage V2 1 (second high resistance voltage) applied to the selected bit line BL. ) Is output.
- V2 1 second high resistance voltage
- Is output the number of transistors h set in the portion connecting the first electrode E1 and the bit line BL of the resistance variable element RR included in the memory cell is three.
- the third high-resistance voltage generation circuit 127 is configured to increase the resistance of the memory cell MC located in the third column from the left of the memory block by applying a voltage V2 2 (third high-resistance voltage) applied to the selected bit line BL. ) Is output.
- V2 2 third high-resistance voltage
- the fourth high-resistance voltage generating circuit 128 is configured to increase the resistance of the memory cell MC located in the fourth column from the left of the memory block by applying a voltage V2 3 (fourth high-resistance voltage) applied to the selected bit line BL. ) Is output.
- V2 3 fourth high-resistance voltage
- each memory cell has a low resistance when the selected source line SL is set to a high potential and the selected bit line BL is set to a low potential (for example, ground potential) (in the example of the first embodiment, as shown in FIG. 6A). Since the substrate bias effect hardly occurs in the selected transistor, the applied voltage is applied as it is between both electrodes of the resistance variable element RR as it is. On the other hand, when the selected source line SL is set to a low potential and the selected bit line BL is set to a high potential (in the example of the first embodiment, the resistance is increased as shown in FIG. 6B), the selection transistor is reversed. Since the substrate bias effect of the bias occurs, the voltage actually applied between both electrodes of the resistance variable element RR becomes smaller than the voltage applied between the selected source line SL and the selected bit line BL.
- a low potential for example, ground potential
- FIG. 45 is a diagram illustrating a circuit used for simulating a potential drop due to the substrate bias effect.
- A-Tr is a control transistor existing between the power supply circuit and the memory cell
- Tr 0 to Tr 15 are transistors connected to each memory cell.
- V E0 to V E15 are voltages on the source line when V D (V D0 to V D15 ) of each transistor constituting the memory cell is calculated as 0V.
- FIG. 46 is a diagram showing a result of obtaining a potential drop due to a substrate bias effect of V D (V D0 to V D15 ) of each transistor based on the circuit diagram of FIG. 45 by simulation.
- the transistor configuration used in the simulation is common to all of Tr 0 to Tr 15 and A-Tr.
- transistors provided continuously so that the first main terminal (source / drain) of one adjacent transistor and the second main terminal (source / drain) of the other transistor are connected to each other.
- the control terminals (gates) of the respective transistors are connected, and the same potential (V G ) is applied.
- a lower electrode of a resistance variable element is connected to each of connection portions (main terminals) of two adjacent transistors.
- the resistance variable element to the right of the main terminal of the rightmost transistor Tr 0 is not connected, the right of the main terminal is connected to the bit line BL I think. All upper electrodes of the resistance variable element are considered to be grounded.
- the first embodiment has a configuration in which four memory cells are connected to one serial path (a configuration in which four memory cells are included in one row in the memory block). Note that by adjusting the V G and V BL, can be connected more memory cells to one series path.
- VBL the degree of potential drop due to the substrate bias effect varies depending on the position on the series path (the number of transistors included in the path connecting the resistance variable element and the bit line).
- the voltage actually applied to the resistance variable element also changes.
- the applied voltage is constant regardless of the position on the series path. Therefore, according to the path length of the shortest serial path connecting the first electrode E1 of the memory cell and the bit line BL (the number of transistors included in the shortest serial path connecting the resistance variable element and the bit line), the resistance It is desirable to adjust VBL in advance so that the voltage applied between both electrodes of the variable element RR is equal regardless of the position in the memory block.
- the first high-resistance voltage generation circuit 125, the second high-resistance voltage generation circuit 126, the third high-resistance voltage generation circuit 127, and the fourth high-resistance voltage generation circuit 128 are used, and the memory cell the V BL by changing the V2 0 ⁇ V2 3 as described above, to realize such control in response to the position.
- the voltage applied between both electrodes of the resistance variable element RR is constant regardless of the position of the memory cell MC, and the resistance value after writing is made more constant than in the previous configuration. And unnecessary voltage stress applied to the resistance variable element can be further suppressed.
- the nonvolatile memory device according to the present invention is useful as a nonvolatile memory device that realizes a memory cell of 4F 2 while effectively suppressing a current flowing through an unselected memory cell.
Abstract
Description
[装置構成]
図1は、本発明の第1実施形態に係る不揮発性記憶装置100の回路構成の一例を示すブロック図である。図2は、図1におけるメモリセルMCの部分を拡大した図である。なお、添え字は対応するメモリブロックの行または列の番号を示す。
メモリセルMCのそれぞれについて、第2電極E2がそのメモリセルMCに対応するソース線SLに接続されている。第2電極E2はそのメモリセルMCに対応するソース線SLの一部であってもよい。
図3は、1個のメモリブロックを示す図であり、図3(a)はメモリブロックの上面図、図3(b)は図3(a)の等価回路図である。図3(b)は、図1におけるメモリブロックMBを抜き出して拡大したものになっている。
図4は、図3の一点鎖線で示したメモリブロックの断面を示す図であり、図4(a)は図3の線A-A’に沿って切った断面図、図4(b)は図3の線B-B’に沿って切った断面図、図4(c)は図3の線C-C’に沿って切った断面図、図4(d)は図3の線D-D’に沿って切った断面図、図4(e)は図3の線E-E’に沿って切った断面図、図4(f)は図3の線F-F’に沿って切った断面図である。以下、図4においてソース線SLが伸びる方向を前後方向、基板の厚み方向を上下方向、ワード線WLの伸びる方向を左右方向とする。図4において、同じメッシュ模様は原則的にほぼ同じ材料からなることを示す。ただし、同じメッシュ模様で示された部分であっても、詳細な組成や成分は異なる場合がある。
図5は、本発明の第1実施形態にかかる不揮発性記憶装置に含まれる抵抗変化型素子の特性(電圧と抵抗値との関係)の一例を示す図である。
以上のように構成された不揮発性記憶装置100について、その動作の概略を以下説明する。
図7~図42は、本発明の第1実施形態の不揮発性記憶装置を製造する工程を示す図である。なお、不揮発性記憶装置100を製造するためには、図7~42以外の工程も必要であるが、それらの工程については周知の方法を用いることができるため記載を省略する。
図43は、本発明の第1実施形態の変形例にかかる不揮発性記憶装置100’の回路構成の一例を示すブロック図である。図43に示すように、それぞれのメモリブロック毎に直列経路のそれぞれの両端がビット線(第3配線)と接続されていてもよい。
図44は、本発明の第2実施形態にかかる不揮発性記憶装置の回路構成の一例を示すブロック図である。
本実施形態においても、第1実施形態と同様の変形例が可能である。
102 カラムデコーダ
104 ロウデコーダ
106 メモリセルアレイ
108 アドレス入力回路
110 制御回路
112 電源回路
114 データ入出力回路
116 書込回路
118 クランプ回路
120 センスアンプ
122 低抵抗化電圧生成回路
124 高抵抗化電圧生成回路
125 第1高抵抗化電圧生成回路
126 第2高抵抗化電圧生成回路
127 第3高抵抗化電圧生成回路
128 第4高抵抗化電圧生成回路
130 P型シリコン基板層
132 二酸化珪素層
134 P注入領域
136 白金シリサイド層
138 Si3N4部
140 タンタル酸化物層
142 窒化タンタル層
144 タングステン層
146 Si3N4層
148 二酸化珪素層
149 チタン/窒化チタン層
150 チタン/窒化チタン層
152 タングステン層
153 コンタクト
154 銅層
156 二酸化珪素層
158 二酸化珪素層
160 ポリシリコン層
161 コンタクト
162 銅層
163 溝
164 メモリ溝
166 コンタクト配線溝
168 溝
170 ホール
172 溝
174 ホール
200 不揮発性記憶装置
BL ビット線
CL コンタクト配線
C1、C2 コンタクト
D/S ドレイン/ソース
E1 第1電極
E2 第2電極
G ゲート
MC メモリセル
RR 抵抗変化型素子
SL ソース線
T1 第1主端子(ドレイン/ソース)
T2 第2主端子(ドレイン/ソース)
T3 制御端子(ゲート)
TR トランジスタ
VR 抵抗変化層
WL ワード線
Claims (6)
- 第1平面内において第1方向に互いに平行に伸びる複数の第1配線と、
前記第1平面と平行な第2平面内において第2方向に互いに平行にかつ前記第1配線と立体交差するように伸びる複数の第2配線と、
前記第1配線と前記第2配線との立体交差点のそれぞれに対応して設けられたメモリセルとを備え、
前記メモリセルのそれぞれは1個のトランジスタと1個の抵抗変化型素子とを備え、
前記トランジスタのそれぞれは第1主端子と第2主端子と制御端子とを備え、
前記抵抗変化型素子のそれぞれは第1電極と第2電極と前記第1電極および前記第2電極の間に設けられた抵抗変化層とを備え、
前記第1方向に沿って並ぶ複数の前記メモリセルについて、隣接する2個のメモリセルに含まれる一方のメモリセルの第1主端子と他方のメモリセルの第2主端子とが接続されることで、複数のメモリセルの主端子を順次に直列に接続して前記第1方向に伸びる直列経路が形成され、
前記メモリセルのそれぞれについて、
前記制御端子が当該メモリセルに対応する前記第1配線に接続され、
前記第2電極が前記メモリセルに対応する前記第2配線の一部であるか前記第2配線に接続され、
前記第1電極が前記メモリセルに対応する前記直列経路の一部であるか直列経路に接続されている、
不揮発性記憶装置。 - 前記第1方向に互いに平行に伸びる複数の第3配線を備え、
前記第1方向に沿って並ぶ複数のメモリセルは、連続して並んだ所定個数のメモリセルにより複数のメモリブロックを構成し、
それぞれの前記メモリブロック毎に前記直列経路が前記第3配線と接続されている、請求項1に記載の不揮発性記憶装置。 - それぞれの前記メモリブロック毎に前記直列経路のそれぞれの両端が前記第3配線と接続されている、請求項2に記載の不揮発性記憶装置。
- それぞれの前記メモリセルに含まれる抵抗変化型素子に電圧を印加するための電源回路を備え、
前記電源回路は、選択されたメモリセルについて、対応する前記直列経路と対応する前記第3配線との接続部から前記メモリセルの第1電極までの前記直列経路に含まれるトランジスタの数に応じて出力する電圧を変化させるように構成されている、請求項2に記載の不揮発性記憶装置。 - 前記第1主端子および前記第2主端子はそれぞれシリサイド層を有し、
前記シリサイド層が前記第1電極を構成する、請求項1に記載の不揮発性記憶装置。 - 前記シリサイド層は白金シリサイドからなる、請求項5に記載の不揮発性記憶装置。
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