JP2009081251A - Resistance change element, manufacturing method thereof, and resistance change type memory - Google Patents

Abstract

A variable resistance element having a new structure that can cope with further miniaturization and high integration of elements while reducing the load of the process of forming a variable resistance portion.
A substrate includes a substrate, a first electrode and a second electrode disposed on the substrate, and a resistance change portion disposed between the first and second electrodes. There are two or more states having different electrical resistance values between the first and second electrodes, and the driving voltage or current is applied to the resistance change unit 12 through the first and second electrodes, thereby obtaining the two or more states. A variable resistance element 1 that changes from one state selected from the above state to another state, and a laminated body 15 having a laminated structure of the first electrode 11 and the insulating film 14 is disposed on the substrate 10, The resistance change portion 12 is in contact with the stacked body 15 such that the side surfaces thereof are in contact with both side surfaces of the first electrode 11 and the insulating film 14, and the resistance change portion 12 and the second electrode 13 are connected to each side surface. The elements are in contact with each other.
[Selection] Figure 1

Description

  The present invention relates to a resistance change element whose electric resistance value changes by application of a drive voltage or a drive current, a manufacturing method thereof, and a resistance change type memory including the element as a memory element.

  In recent years, there has been an increasing demand for miniaturization of memory elements, and a nonvolatile memory element that records information not by charge capacity but by a change in electric resistance value has attracted attention as a memory element that is not easily affected by the miniaturization. One type of such a memory element is a resistance change element whose electric resistance value changes when a driving voltage or current is applied.

  The resistance change element has a resistance change portion and a pair of electrodes arranged so as to sandwich the resistance change portion. Usually, a lower electrode, a resistance change layer, and an upper electrode are sequentially stacked on a substrate. Has a structured. This element can take two or more states having different electric resistance values, and the state can be changed by applying a predetermined voltage or current between the electrodes. One selected state is basically maintained (ie, non-volatile) until a predetermined voltage or current is applied again between the electrodes. Such an effect is called a giant resistance change effect (CER: Colossal Electro-Resistance). The CER effect is not easily affected by miniaturization, and a large resistance change can be obtained with the CER effect. Therefore, the resistance change element is highly expected as a next-generation nonvolatile memory element that can be miniaturized. .

  In the report (Non-patent Document 1) described in Journal of Applied Physics by Hick Mott, hysteresis is observed in the current-voltage characteristics of various oxides. The possibility has been pointed out.

  JP 2002-537627 A (Patent Document 1) discloses a resistance change element using various oxides, and a nonvolatile semiconductor memory constructed using this element is a resistance change random access memory. It is called (Re-RAM) and has attracted attention. Since Re-RAM is not easily restricted by miniaturization, there is a high expectation for further high integration.

  In Japanese Patent No. 3919205 (Patent Document 2), iron oxide is studied as a material that exhibits the CER effect.

In Japanese Patent Laid-Open No. 2003-197877 (Patent Document 3), high integration of Re-RAM is achieved by stacking variable resistance elements in multiple layers. The Re-RAM disclosed in Patent Document 3 is a cross-point in which a resistance change layer is arranged at the intersection of a pair of strip-like electrodes (bit lines and word lines) orthogonal to each other when viewed from a direction perpendicular to the main surface of the substrate. Type Re-RAM. In this Re-RAM, a pair of word lines are arranged so as to sandwich the bit line, and the bit lines are shared between the word lines, that is, the electrodes are shared, thereby miniaturizing the device and increasing the integration density. Is planned. Paying attention to the above-mentioned intersection of the word line and the bit line in the Re-RAM in Document 3, at this intersection, two or more resistance change layers are regularly arranged in the stacking direction of each layer constituting the Re-RAM. It can be said that the variable resistance elements that are multi-valued by the number of the arrangements are located at the intersections.
TW Hickmott, "Journal of Applied Physics", 2000, vol.88, pp.2805 JP 2002-537627 A Japanese Patent No. 3919205 JP 2003-197877 A

  For manufacturing a multilayer stack and cross-point type Re-RAM as shown in Patent Document 3, a plurality of resistance change layers are arranged in the stacking direction of each layer constituting the resistance change element (direction perpendicular to the main surface of the substrate). Need to form. For this purpose, it is essential to have a technology that uniformly forms each layer of the device over several layers while ensuring the flatness of the surface. It is currently difficult to secure accurate layer formation control technology. Further, when the composition of the resistance change layer is an oxide, it is necessary to keep the oxygen content that greatly contributes to the resistance value of the layer, but the resistance change layer made of an oxide is generally exposed to an oxygen atmosphere. In reality, it is difficult to form a number of variable resistance layers with a constant oxide composition.

  For this reason, the resistance change part has a new structure that can cope with further miniaturization and higher integration of elements while reducing the load of the process of forming the resistance change part, such as the resistance change part can be formed by the same control technology as before. Realization of an element is desired.

  It is an object of the present invention to provide a variable resistance element having such a novel configuration, a method for manufacturing the variable resistance element, and a variable resistance memory including the element.

  The resistance change element of the present invention includes a substrate, a first electrode and a second electrode disposed on the substrate, and a resistance change portion disposed between the first and second electrodes, There are two or more states with different electrical resistance values between the first and second electrodes, and by applying a driving voltage or current to the resistance change unit via the first and second electrodes, A variable resistance element that changes from one state selected from the two or more states to another state, the laminate having a laminated structure of the first electrode and an insulating film is disposed on the substrate. The resistance change portion is in contact with the stacked body such that the side surfaces thereof are in contact with both side surfaces of the first electrode and the insulating film, and the resistance change portion and the second electrode are respectively The elements are in contact with each other on the side surface.

  The variable resistance element manufacturing method of the present invention is the above-described element manufacturing method of the present invention, which has a laminated structure of a first electrode and an insulating film on a substrate, the first electrode and the insulating A step of forming a first laminate in which a side surface of the film is exposed, and a step of forming a resistance change portion so that the side surface of both the first electrode and the insulating film is in contact with the side surface (B) and a step (c) of forming the second electrode so that the resistance change portion is sandwiched with the first electrode and the side surface of the resistance change portion is in contact with the side surface of the resistance change portion. .

  The resistance change type memory according to the present invention includes the element according to the present invention as a memory element.

  In the element of the present invention, the laminate having the laminated structure of the first electrode and the insulating film, and the resistance change portion are arranged such that the side surface of the resistance change portion is in contact with both side surfaces of the first electrode and the insulation film. It touches. In such an element, for example, a stacked body in which two or more first electrodes are stacked so that insulation between each other is maintained by an insulating film, and each side surface of the two or more electrodes is defined as a side surface of the resistance change portion. By making contact, the variable resistance portion can be shared between the electrodes, and the multi-value of the element can be achieved. That is, in the element of the present invention, as in the element disclosed in Patent Document 3, a large number of resistance change portions (resistance change layers in Patent Document 3) are stacked in a direction perpendicular to the main surface of the substrate by a plurality of processes. Instead, in the most efficient example, the element can be multi-valued by forming one resistance change portion by one process. The element of the present invention having such a configuration can cope with further miniaturization and higher integration while reducing the load of the process of forming the resistance change portion. Further, even when the resistance change portion is made of an oxide, there is little variation in characteristics between the multi-valued resistance change elements in the element, and a highly integrated memory having excellent characteristics can be constructed.

  Hereinafter, the present invention will be specifically described with reference to the drawings. In the following description, the same reference numerals may be given to the same members, and overlapping descriptions may be omitted.

[Resistance change element]
1 and 2 show an example of the variable resistance element of the present invention. FIG. 2 is a plan view of the variable resistance element 1 shown in FIG. 1 as viewed from the top surface (viewed from a direction perpendicular to the substrate 10).

  In the element 1 shown in FIGS. 1 and 2, a first electrode 11, a resistance change portion 12, a second electrode 13, an insulating film 14, an upper wiring electrode 16, and a lower wiring electrode 17 are disposed on a substrate 10. Yes.

  Hereinafter, each of the members in the element 1 shown in FIGS.

  The first electrode 11 has a strip shape extending on a plane parallel to the main surface of the substrate 10, and constitutes a stacked body 15 together with a pair of insulating films 14 that sandwich the electrode 11. It can be said that the stacked body 15 has a stacked structure of the first electrode 11 and the insulating film 14, and the stacking direction of the first electrode 11 and the insulating film 14 in this stacked structure is on the main surface of the substrate 10. It is vertical.

  The resistance change portion 12 has a cylindrical shape in which a direction perpendicular to the main surface of the substrate 10 is a direction in which the central axis extends (a central axial direction). The resistance change unit 12 is in contact with the stacked body 15 such that the side surface (outer peripheral surface) thereof is in contact with both side surfaces of the first electrode 11 and the insulating film 14. The side surface of the first electrode 11 in contact with the resistance change portion 12 and the side surface of the insulating film 14 in contact with the resistance change portion 12 are on the same plane. The resistance change portion 12 has a portion that is in contact with the first electrode 11 over the entire circumference of the outer peripheral surface, and the other portion of the outer peripheral surface is in contact with the insulating layer 14. That is, the first electrode 11 is in contact with a part of the outer peripheral surface of the resistance change portion 12. Considering the first electrode 11 as a reference, the first electrode 11 has a through-hole formed in a peripheral surface having a shape corresponding to the outer peripheral surface of the resistance change portion 12, and the resistance change portion 12 has a through hole. It can be said that it is arranged in the hole.

  The second electrode 13 has a cylindrical shape extending in a direction perpendicular to the main surface of the substrate 10, and the second electrode 13 and the resistance change unit 12 are in contact with each other on each side surface. More specifically, the second electrode 13 has a columnar shape having a peripheral surface corresponding to the inner peripheral surface of the resistance change portion 12, and fills the inside of the cylindrical resistance change layer 12. Are arranged to be. That is, the entire inner peripheral surface of the resistance change portion 12 is in contact with the second electrode 13.

  The first electrode 11 and the second electrode 13 sandwich the resistance change portion 12 in the direction along the main surface of the substrate 10 so as to be in contact with the resistance change portion 12.

  The upper wiring electrode 16 and the lower wiring electrode 17 have a strip shape extending on a plane parallel to the main surface of the substrate 10. The upper wiring electrode 16 is disposed so as to be in contact with the upper surfaces of the resistance change section 12 and the second electrode 13, and is electrically connected to the second electrode 13. The lower wiring electrode 17 is disposed so as to be in contact with the lower surface of the resistance change unit 12 and the second electrode 13, and is electrically connected to the second electrode 13. The lower wiring electrode 17 is embedded in the substrate 10, but such a wiring electrode can be formed by a damascene process. The upper wiring electrode 16 and the lower wiring electrode 17 and the first electrode 11 are orthogonal to each other when viewed from a direction perpendicular to the main surface of the substrate 10.

  The resistance change unit 12 is disposed between the first electrode 11 and the second electrode 13 (see a portion surrounded by a broken line in FIG. 1), and has two or more states having different electric resistance values. . The state of the resistance change unit 12 changes from one state selected from the two or more states to another state by applying a driving voltage or current through the first electrode 11 and the second electrode 13. . That is, in the element 1, there are two or more states in which the electric resistance value between the first electrode 11 and the second electrode 13 is different, and this state is the first electrode 11 and the second electrode 13. The state changes from one state selected from the two or more states to another state by applying a driving voltage or current to the resistance changing unit 12 via the above.

  Typically, the resistance change unit 12 has the two states, that is, a high resistance state with a relatively high electrical resistance value and a low resistance state with a relatively low electrical resistance value. That is, typically, the element 1 has two states (a high resistance state and a low resistance state) in which the electric resistance value between the first electrode 11 and the second electrode 13 is different. Changes from a high resistance state to a low resistance state or from a low resistance state to a high resistance state by application of a driving voltage or current.

  In the element 1, the second electrode 13, the upper wiring electrode 16, and the lower wiring electrode 17 are electrically connected. Therefore, for example, a memory is constructed in which the first electrode 11 is a word line (or bit line) and the upper wiring electrode 16 and / or the lower wiring electrode 17 orthogonal to the first electrode 11 is a bit line (or word line). In this case, by applying a driving voltage or current to the resistance change section 12 via the word line and the bit line, the state of the resistance change section 12 can be changed and the Re-RAM can be operated. Can do.

  FIG. 3 shows another example of the variable resistance element of the present invention. The element 1 shown in FIG. 3 has the same configuration as that of the element 1 shown in FIGS.

  In the element 1 shown in FIG. 3, the stacked body 15 has a stacked structure in which two or more first electrodes 11 and insulating films 14 are alternately stacked. Each of the two or more first electrodes 11 includes: It is in contact with one common resistance change section 12. That is, in the element 1 shown in FIG. 3, the resistance change portion 12 is shared between the plurality of first electrodes 11.

  In such an element 1, unlike the cross-point type Re-RAM disclosed in Document 3, for example, one resistance change is formed without forming a plurality of resistance change layers in the stacking direction of each layer constituting the resistance change element. By forming the portion 12 and sharing the resistance change portion 12 with the plurality of first electrodes 11, multi-valued elements can be realized. That is, in the element 1, when the multi-value is increased, the load of the process of forming the resistance change portion can be reduced, and further miniaturization and higher integration can be realized.

  An example of a configuration that each part of the element of the present invention can take will be described.

  The structure of the laminated body 15 has a laminated structure of the first electrode 11 and the insulating film 14, and both side surfaces of the first electrode 11 and the insulating film 14 included in the laminated body 15 are resistance change portions. As long as it contacts 12 side surfaces, it is not particularly limited.

  The stacking direction of the first electrode 11 and the insulating film 14 in the stacked structure of the stacked body 15 is typically perpendicular to the main surface of the substrate 10 (in other words, the first electrode 11, the insulating film 14, Is typically parallel to the main surface of the substrate 10), but the stacking direction may be inclined from a direction perpendicular to the main surface of the substrate 10. However, since it becomes difficult to obtain the effects of the present invention when the degree of inclination becomes excessively large, the degree of inclination is usually preferably within a few degrees.

  When the stacked body 15 is disposed in contact with the substrate 10, the first electrode 11 may be in contact with the substrate 10, or the insulating film 14 may be in contact therewith. In the example shown in FIGS. 1 to 3, the first electrode 11 is disposed away from the substrate 10, and is sandwiched by the insulating film 14 in the stacked structure.

  The side surface in contact with the resistance change portion 12 in the first electrode 11 and the side surface in contact with the resistance change portion 12 in the insulating film 14 may be on different planes or on the same plane. In the element 1 having both side surfaces on the same plane, for example, as described later, a columnar opening is formed in a stacked body having a stacked structure of the first electrode 11 and the insulating film 14, and the inside of the formed opening Since the resistance change portion 12 can be arranged and manufactured, the load of the formation process of the resistance change portion 12 can be further reduced when the element is multi-valued.

  In the element of the present invention, as in the example shown in FIG. 3, the stacked body 15 has a stacked structure in which two or more first electrodes 11 and insulating films 14 are alternately stacked, and the two or more first electrodes At least two electrodes selected from the electrodes 11 may be in contact with the common resistance change portion 12. In such an element 1, multi-value can be realized by sharing the resistance changing unit 12 with a plurality of electrodes (electrodes to which a driving voltage or current is applied). In this case, all of the first electrodes 11 included in the stacked body 15 may be in contact with one common resistance change unit 12.

  In this case, the side surfaces of the at least two electrodes that are in contact with the resistance change portion may be on different planes or on the same plane. The element 1 whose side surfaces are on the same plane is formed by, for example, forming a columnar opening in a stacked body having a stacked structure of two or more first electrodes 11 and an insulating film 14 as described later. Since the variable resistance portion 12 can be arranged and manufactured in the opening, the load of the formation process of the variable resistance portion 12 can be further reduced when the element is multi-valued.

  The shape of the first electrode 11 is not particularly limited as long as the above relationship is satisfied between the laminated film 14 and the resistance change portion 12. However, from the viewpoint of promoting element miniaturization and high integration, the shape of the first electrode 11 is usually flat. It may be a strip as one form. In particular, when a resistance change type memory is constructed with two or more elements, the first electrode 11 is preferably strip-shaped, and the strip-shaped first electrode 11 is on a plane parallel to the main surface of the substrate. Is preferably elongated.

  The shape of the resistance change portion 12 is not particularly limited as long as the relationship between the stacked body 15 (the first electrode 11 and the insulating film 14) and the second electrode 13 is satisfied. For example, the resistance change unit 12 may have a columnar shape extending in a direction perpendicular to the main surface of the substrate 10. Examples of the columnar shape include a prismatic shape, a columnar shape, and an elliptical columnar shape. As an example, in the case where the resistance change portion 12 has a quadrangular prism shape, the first and second electrodes may be in contact with opposite side surfaces of the resistance change portion 12, for example.

  Further, for example, the resistance change unit 12 may have a cylindrical shape having a direction perpendicular to the main surface of the substrate 10 as a central axis direction. Examples of the cylindrical shape include a rectangular cylindrical shape, a cylindrical shape, and an elliptical cylindrical shape. When the resistance change part 12 is cylindrical, the 1st and 2nd electrode may be in contact with the outer peripheral surface and inner peripheral surface of the resistance change part 12, respectively. In the example shown in FIGS. 1 to 3, the resistance change portion 12 has a cylindrical shape with the direction perpendicular to the main surface of the substrate 10 as the central axis direction, and the first electrode 11 is formed on the outer peripheral surface of the resistance change portion 12. It touches. Further, in the above example, the first electrode 11 has a through hole formed with a peripheral surface having a shape corresponding to the outer peripheral surface of the resistance change portion 12, and the resistance change portion 12 It arrange | positions in the said through-hole. At this time, the first electrode 11 is preferably a flat plate having a main surface parallel to the main surface of the substrate 10. In consideration of the construction of the resistance change memory, the first electrode 11 is on a surface parallel to the main surface of the substrate 10. It is preferable that it is a belt-like shape that extends.

  The shape of the second electrode 13 is not particularly limited as long as the relationship with the resistance change unit 12 is satisfied.

  When the resistance change portion 12 has a cylindrical shape with the direction perpendicular to the main surface of the substrate 10 as the central axis direction, the second electrode 13 is, for example, a peripheral surface having a shape corresponding to the inner peripheral surface of the resistance change portion 12 And may be disposed inside the resistance change portion 12. At this time, the second electrode 13 is in contact with the inner peripheral surface of the resistance change portion 12, and the resistance change portion 12 has a portion in contact with the second electrode 13 over the entire circumference of the inner peripheral surface. . Examples of the configuration of such an element include the examples shown in FIGS. In the above example, it can be said that the second electrode 13 is disposed so as to fill the inside of the cylindrical resistance change portion 12. By configuring the element in this way, two or more first electrodes 11 are formed. Even when the element is multi-valued by the arrangement of the element, the operation of the element can be further stabilized. Further, by arranging the upper wiring electrode 16 and / or the lower wiring electrode 17 electrically connected to the second electrode 13, it becomes easier to construct a resistance change type memory in which two or more elements 1 are combined. .

  The upper wiring electrode 16 and the lower wiring electrode 17 should just be arrange | positioned as needed. Moreover, although the electrode to which each wiring electrode is connected is the 2nd electrode 13 in the example shown in FIGS. 1-3, it is not limited to a 2nd electrode in particular. 1-3, the strip-like upper wiring electrode 16 and / or the lower wiring electrode 17 electrically connected to the second electrode 13 are arranged above and / or below the resistance change section 12. This makes it easier to construct a resistance change type memory in which two or more elements 1 are combined. In particular, the first electrode 11 and the wiring electrode are formed in a strip shape extending on a plane parallel to the main surface of the substrate 10, and both are orthogonal to each other when viewed from a direction perpendicular to the main surface of the substrate 10. Therefore, it is easier to construct a highly integrated resistance change memory.

The type of the substrate 10 is not particularly limited, and is typically a semiconductor substrate such as a Si substrate, or an insulator substrate such as a TEOS (tetraethylorthosilicate) substrate, a thermally oxidized Si (SiO ₂ ) substrate, or a SiOC substrate. . The substrate 10 made of an organic material having a low dielectric constant may be used. When a semiconductor substrate is used as the substrate 10, it is easy to produce and combine the variable resistance element of the present invention and a semiconductor element different from the element on the same substrate. The semiconductor substrate includes a substrate on which a transistor, a contact plug, and the like are formed.

  The first electrode 11 and the second electrode 13 may be made of a material having excellent conductivity (for example, a specific resistance of 100 mΩ · cm or less). Specific examples of the material include copper (Cu), aluminum (Al), platinum (Pt), tantalum (Ta), tungsten (W), tantalum nitride (Ta—N), titanium nitride (Ti—N), aluminum titanium nitride (Ti—Al—N), and the like can be given. 1 to 3, when the second electrode 13 is filled in the cylindrical resistance change portion 12, the electrode is in contact with the inner peripheral surface of the resistance change portion 12. A thin film made of the exemplified material may be formed, and the inside of the film may be filled with a conductor such as tungsten.

The insulating film 14 that constitutes the stacked body 15 together with the first electrode 11 may basically be made of an insulator. Specific examples of the insulator include SiO ₂ , Al ₂ O ₃ , and SiOC. The insulating film 14 made of an organic material having a low dielectric constant may be used.

  Similar to the first and second electrodes 11 and 13, the upper wiring electrode 16 and the lower wiring electrode 17 may be made of a material having excellent conductivity.

  The material (resistance change material) constituting the resistance change portion 12 has two or more states in which the resistance change portion 12 has different electric resistance values, and the driving voltage and current through the first and second electrodes 11 and 13. As long as it can be changed from one state selected from the two or more states to another state by application of the above, there is no particular limitation. A variable resistance material used for a general variable resistance element can be widely used.

  The variable resistance portion 12 may be mainly composed of a metal oxide, and the metal oxide may be at least selected from iron (Fe), titanium (Ti), tungsten (W), tantalum (Ta), and hafnium (Hf). An oxide of one kind of element is preferable because high resistance change characteristics can be realized. In addition, a main component means the material (component) which occupies 50 weight% or more in content rate among the materials which comprise the resistance change part 12. FIG.

  4 and 5 show another example of the variable resistance element of the present invention. FIG. 5 is a plan view of the element 1 shown in FIG. 4 as viewed from above. The element 1 shown in FIGS. 4 and 5 is similar to the element 1 shown in FIG. 1 except that a conductive film (nonlinear conductive film) 18 having nonlinear electrical characteristics is formed in a portion of the first electrode 11 that is in contact with the resistance change portion 12. 2 has the same configuration as the element 1 shown in FIG. By using such an element 1, a non-linear resistance change characteristic can be realized. The “nonlinear resistance change characteristic” may be symmetric or asymmetric with respect to application of a driving voltage or current to the element.

  The nonlinear conductive film 18 may be formed in a portion of the second electrode 13 that is in contact with the resistance change portion 12. That is, in the element of the present invention, the non-linear conductive film 18 may be formed in a portion in contact with the resistance change portion 12 in at least one electrode selected from the first electrode 11 and the second electrode 13. The nonlinear conductive film 18 is a part of the at least one electrode.

  The nonlinear conductive film 18 preferably has a Schottky conduction action.

The non-linear conductive film 18 may be a material that exhibits non-linear electrical characteristics in relation to the material constituting the resistance change section 12 as well as a material that alone exhibits non-linear electrical characteristics. For example, when the resistance change portion 12 is made of iron oxide (FeO _x1 : typically 3/2 ≧ X1> 4/3), the nonlinear conductive film 18 is made of gold (Au) or platinum (Pt). There may be.

  The nonlinear conductive film 18 may be a plated layer (plated electrode layer) formed on the surface of a bulk electrode.

  A plurality of elements of the present invention can be arranged. For example, a resistance change type memory can be constructed by arranging a plurality of elements of the present invention as memory elements.

  6 and 7 show an example of a configuration in which the elements 1 shown in FIGS. 4 and 5 are arranged in an array. FIG. 7 is a plan view of the element group 2 shown in FIG. In the element group 2 shown in FIGS. 6 and 7, three elements 1 are arranged in an array. In the element group 2, the first electrode 11 has a strip shape extending on a plane parallel to the main surface of the substrate 10, and is shared between the elements 1. The first electrode 11 is orthogonal to the strip-like upper wiring electrode 16 and lower wiring electrode 17 in each element 1.

  A plurality of element groups 2 shown in FIGS. 6 and 7 can be arranged while sharing the upper wiring electrode 16 and the lower wiring electrode 17, and the elements 1 can be arranged in a matrix (matrix shape). A configuration example of such an element group is shown in FIG.

  In the element group 3 shown in FIG. 8, the six elements 1 are arranged in a matrix, and the first band-like element extending on a plane parallel to the main surface of the substrate 10 between the elements 1 arranged in the row direction. The electrode 11 is shared. Further, between the elements 1 arranged in the column direction, a strip-like upper wiring electrode 16 and a lower wiring electrode 17 that extend on a plane parallel to the main surface of the substrate 10 are shared. The first electrode 11, the upper wiring electrode 16, and the lower wiring electrode 17 are orthogonal to each other when viewed from the direction perpendicular to the main surface of the substrate 10.

  In the element group 3 shown in FIG. 8, for example, the upper wiring electrode 16 (or the lower wiring electrode 17) may be a bit line and the first electrode 11 may be a word line (the bit line and the word line may be reversed). ) By selecting one bit line and word line and applying a driving voltage or current to the element 1 (1a) located at the intersection (see the arrow in FIG. 8), the electric resistance value of the element 1a The state can be changed. Here, by assigning information (bits) to the state of the electrical resistance value of the element 1a, the application of the drive voltage or current to the element 1a via the selected bit line and word line can be changed. Writing or reading of information from the element 1a can be performed. That is, with the configuration shown in FIG. 8, it is possible to realize a resistance change type memory having random accessibility.

  FIG. 9 shows an equivalent circuit of the element group 3 shown in FIG. The symbol of the diode in the element 1 (1a) corresponds to the nonlinear conductive film 18 in the element. The arrows in FIG. 9 indicate application of a driving voltage or current to the element 1a via the selected bit line 32 and word line 33.

  The structure of the element of the present invention is not limited to the examples shown in FIGS. Other structures can be employed as long as the first electrode, the resistance change portion, the second electrode, and the stacked body having the stacked structure of the first electrode and the insulating film satisfy the above relationship. For example, the element 1 as shown in FIG. 10 may be used.

  The element 1 shown in FIG. 10 has the following configuration. The resistance change portion 12 has a cylindrical shape having a direction perpendicular to the main surface of the substrate 10 as a central axis direction, and has a shape stretched in a direction in which the strip-like upper wiring electrode 16 and the lower wiring electrode 17 extend. In other words, the resistance changing portion 12 has a short axis direction in which the distance between the inner peripheral surfaces facing each other is relatively small and the distance between the inner peripheral surfaces facing each other in a cross section parallel to the main surface of the substrate 10. Large major axis direction. The resistance change portion 12 is formed with a slit-like space having a length in the major axis direction, a width in the minor axis direction, and a depth in a direction perpendicular to the main surface of the substrate 10. The space is filled with the second electrode 13.

  The element 1 shown in FIG. 10 includes strip-shaped first electrodes 11a and 11b extending in a direction orthogonal to the direction in which the upper wiring electrode 16 and the lower wiring electrode 17 extend, and the first electrodes 11a and 11b are Further, they are separated from each other in a direction parallel to the main surface of the substrate 10 and are in contact with the outer peripheral surface of the resistance change portion 12. The first electrodes 11a and 11b are formed with notches having side surfaces having a shape corresponding to a part of the outer peripheral surface of the resistance change portion 12, and the resistance change portion 12 includes the first electrodes 11a and 11b. It can be said that it is arrange | positioned so that it may fit in the said notch part. In such an element 1, the resistance change portion 12 can be shared between the first electrodes 11 a and 11 b, so that multi-value can be achieved. High integration is possible.

  In the element shown in FIG. 10, the resistance change portion 12 is shared by two or more first electrodes 11 (11a, 11b) separated in a direction parallel to the main surface of the substrate 10, but further shown in FIG. Even if the first electrodes 11 that are spaced apart from each other in the direction perpendicular to the main surface of the substrate 10 are arranged like the element, the resistance change portion 12 is shared by the first electrodes 11 together. Good. In this case, the device can be further miniaturized and highly integrated.

The junction area of the element of the present invention is not particularly limited, but may be 0.05 μm ² or less, for example. Here, the “junction area” means the smaller area selected from the contact area between the resistance change portion 12 and the first electrode 11 and the contact area between the resistance change portion 12 and the second electrode 13. To do.

  A more specific example of the resistance change type memory including the element of the present invention as a memory element will be described later.

[Method of manufacturing variable resistance element]
The element of the present invention described above can be formed by, for example, the manufacturing method of the present invention.

  That is, the manufacturing method of the present invention is a manufacturing method of the element of the present invention, which has a laminated structure of the first electrode and the insulating film, and the side surfaces of the first electrode and the insulating film are exposed. A step (a) of forming a first laminated body on a substrate, a step (b) of forming a resistance change portion so that the side surface of the first stacked body and the side surface of both the first electrode and the insulating film are in contact with each other; A step (c) of forming the second electrode so that the side surface of the resistance change portion is in contact with the side surface of the resistance change portion while holding the resistance change portion together with the first electrode.

  In the manufacturing method of the present invention, in the step (a), a first laminated body having a laminated structure in which two or more first electrodes and insulating films are alternately laminated is formed, and in the step (b), two or more The resistance change portion may be formed so that its side surface is in contact with the side surface of at least two electrodes selected from the first electrodes.

  In the manufacturing method of the present invention, in the step (a), a second stacked body having a stacked structure of the first electrode and the insulating film is formed on the substrate, and the first stacked body is formed with the first stacked body. The first stacked body may be formed by forming an opening so that the side surfaces of the electrode and the insulating film are exposed.

  At this time, in the step (a), a columnar opening having a central axis direction in a direction perpendicular to the main surface of the substrate may be formed in the second stacked body. After this, in step (b), a cylindrical resistance change portion having an outer peripheral surface having a shape corresponding to the inner peripheral surface of the opening is formed in the formed opening, and in step (c), the step ( A columnar second electrode having a peripheral surface corresponding to the inner peripheral surface of the resistance change portion may be formed inside the resistance change portion formed in b).

  The manufacturing method of the present invention may further include a step of forming a strip-shaped wiring electrode electrically connected to the second electrode.

  In the manufacturing method of this invention, arbitrary processes other than process (a)-(c) may be included.

  A specific example of the device manufacturing method of the present invention will be described with reference to FIGS.

  First, as shown in FIGS. 11A and 11B, strip-like lower wiring electrodes 17 extending in a direction perpendicular to the paper surface are formed in a stripe pattern on the surface of the substrate 10. 11B corresponds to the cross section AA in FIG. 11A, and similarly in the subsequent FIGS. 12 to 19, the above cross section in FIG. (Not shown) is shown in (b).

  In the example shown in FIG. 11, the lower wiring electrode 17 is embedded in the substrate 10, and the surface of the lower wiring electrode 17 and the surface of the substrate 10 are on the same plane. Such a lower wiring electrode 17 can be formed by a damascene process. When copper (Cu) is used for the lower wiring electrode 17, the wiring electrode can be formed by a Cu damascene process. However, Cu does not need to be exposed on the surface of the lower wiring electrode 17. For example, a conductive material such as Ta—N can be used. The material may be coated with a material.

  Next, as illustrated in FIG. 12, a stacked body (second stacked body) in which the insulating films 14 and the conductive films 21 are alternately stacked is formed on the substrate 10 and the lower wiring electrode 17. In the example illustrated in FIG. 12, the second stacked body includes a three-layer insulating film 14 and a two-layer conductive film 21 disposed between the adjacent insulating films 14. The number of stacked layers of the film 21 and the insulating film 14 is not particularly limited.

  Next, as shown in FIG. 13, the second stacked body is finely processed to form the conductive film 21 as the first electrode 11. In the example shown in FIG. 13, the first electrode 11 is finely processed so as to have a belt shape orthogonal to the lower wiring electrode 17 when viewed from the direction perpendicular to the main surface of the substrate 10. The method of microfabrication is not particularly limited, and for example, a lithography method and an etching method can be used.

  Next, as shown in FIG. 14, after an insulating material is deposited on the entire surface including the substrate 10, the lower wiring electrode 17, and the first stacked body, the surface is planarized by a CMP (chemical mechanical polishing) method or the like. Then, an insulating layer 22 is formed to cover the substrate 10, the lower wiring electrode 17, and the first stacked body. Thereby, the side surface of the first electrode 11 is covered with the insulating layer 22. The insulating material to be deposited is not particularly limited, and for example, TEOS may be used.

  Next, as shown in FIG. 15, when viewed from the direction perpendicular to the main surface of the substrate 10, the lower wiring electrode 17 is exposed at the portion where the lower wiring electrode 17 and the first electrode 11 intersect. Part 23 is formed. The opening 23 may be formed by a known method, and the shape thereof may be adjusted according to the shape of the resistance change portion to be formed. Thereby, the second stacked body has a multilayer structure of the first electrode 11 and the insulating film 14, and becomes the first stacked body in which the side surfaces of the first electrode 11 and the insulating film 14 are exposed.

  Next, as shown in FIG. 16, a resistance change material 24 is deposited inside the opening 23. At this time, the resistance change material 24 is deposited on the bottom surface (exposed surface of the lower wiring electrode 17) and the side surface of the opening 23, but the inside of the opening 23 is not filled with the resistance change material 24.

  Next, as shown in FIG. 17, the resistance change material 24 deposited on the bottom surface of the opening 23 and the insulating layer 22 is removed by an etching method or the like, and the resistance change material 24 deposited on the side surface of the opening 23 is resisted. The change unit 12 is assumed. In removing the variable resistance material 24, a dry etching method with high directivity may be used.

  Next, as shown in FIG. 18, a conductive material 25 is deposited so as to fill the inside of the opening 23. The conductive material 25 may be deposited so as to ensure electrical connection with the lower wiring electrode 17. As a result, the inside of the opening 23 is filled with the cylindrical resistance change portion 12 and the conductive material 25 filled in the resistance change portion 12.

  Next, as shown in FIG. 19, the conductive material 25 deposited on the insulating layer 22 is removed by a CMP method or the like, the surface of the insulating layer 22 is planarized, and the conductive material embedded in the opening 23 is used. Reference numeral 25 denotes a plug-like second electrode 13. Next, the strip-shaped upper wiring electrode 16 extending in the same direction as the direction in which the lower wiring electrode 17 extends is connected to the resistance change unit 12 and the second so that electrical connection with the second electrode 13 is ensured. It is possible to realize the element 1 of the present invention and an element group in which the elements are arranged. The upper wiring electrode 16 can be formed by a known method in combination with a general lithography method or etching method.

  In the example shown in FIGS. 11 to 19, the resistance change material 24 deposited on the bottom surface of the opening 23 is removed (see FIG. 17), but the resistance change material 24 deposited on the bottom surface is not necessarily removed. . In this case, as shown in FIG. 20, the element 1 in which the resistance change portion 12 has a bottomed cylindrical shape is formed, but a driving voltage or current is applied using the upper wiring electrode 16 as a bit line (or word line). Thus, the element 1 can be driven. In the example shown in FIG. 20, the resistance change portion 12 is directly formed on the substrate 10. However, such an element 1 is formed on the main surface of the substrate 10 in the first or second stacked body, for example. An opening 23 is formed in a portion where the lower wiring electrode 17 is not formed when viewed from the vertical direction so that the substrate 10 is exposed, and a resistance change material 24 and a conductive material 25 are deposited in the formed opening 23. Can be formed.

  Another example of the device manufacturing method of the present invention will be described with reference to FIGS.

  First, as shown in FIGS. 21A and 21B, strip-like lower wiring electrodes 17 extending in a direction perpendicular to the paper surface are formed in a stripe pattern on the surface of the substrate 10. The method for forming the lower wiring electrode 17 may be the same as the example shown in FIG. 21B corresponds to the cross section AA in FIG. 21A, and similarly in the subsequent FIGS. 22 to 29, the cross section in FIG. (Not shown) is shown in (b).

  Next, as illustrated in FIG. 22, a stacked body (second stacked body) in which the insulating films 14 and the conductive films 21 are alternately stacked is formed on the substrate 10 and the lower wiring electrode 17. The formation of the second stacked body may be similar to the example shown in FIG.

  Next, as shown in FIG. 23, the opening 23 is exposed so that the lower wiring electrode 17 is exposed at a portion where the lower wiring electrode 17 and the conductive film 21 intersect when viewed from the direction perpendicular to the main surface of the substrate 10. Form. The opening 23 may be formed by a known method, and the shape thereof may be adjusted according to the shape of the resistance change portion to be formed. Thereby, the second stacked body becomes the first stacked body.

  Next, as shown in FIG. 24, a resistance change material 24 is deposited inside the opening 23. At this time, the resistance change material 24 is deposited on the bottom surface (exposed surface of the lower wiring electrode 17) and the side surface of the opening 23, but the inside of the opening 23 is not filled with the resistance change material 24.

  Next, as shown in FIG. 25, the resistance change material 24 deposited on the bottom surface of the opening 23 and the stacked body of the conductive film 21 and the insulating film 14 is removed by an etching method or the like, and the side surface of the opening 23 is removed. The resistance change material 24 deposited on is used as the resistance change portion 12. In removing the variable resistance material 24, a dry etching method with high directivity may be used.

  Next, as shown in FIG. 26, a conductive material 25 is deposited so as to fill the inside of the opening 23. The conductive material 25 may be deposited so as to ensure electrical connection with the lower wiring electrode 17. As a result, the inside of the opening 23 is filled with the cylindrical resistance change portion 12 and the conductive material 25 filled in the resistance change portion 12.

  Next, as shown in FIG. 27, the conductive material 25 deposited on the stacked body of the conductive film 21 and the insulating film 14 is removed by a CMP method or the like to planarize the surface of the stacked body and open the opening 23. The conductive material 25 embedded in is used as the plug-like second electrode 13.

  Next, as illustrated in FIG. 28, the stacked body of the conductive film 21 and the insulating film 14 is finely processed, and the conductive film 21 is used as the first electrode 11. The method of microfabrication is not particularly limited, and for example, a lithography method and an etching method can be used. Thereafter, an insulating material is deposited on the entire surface including the substrate 10, the lower wiring electrode 17, and the stacked body, and then the surface is planarized by a CMP method or the like to cover the substrate 10, the lower wiring electrode 17, and the stacked body. Form. Thereby, the side surface of the first electrode 11 is covered with the insulating layer 22. The deposited insulating material may be planarized so that the resistance change portion 12 and the second electrode 13 are exposed. The insulating material to be deposited is not particularly limited, and for example, TEOS may be used.

  Next, as shown in FIG. 29, the strip-shaped upper wiring electrode 16 extending in the same direction as the direction in which the lower wiring electrode 17 extends is secured to ensure electrical connection with the second electrode 13. Formed on the resistance change section 12 and the second electrode 13, the element 1 of the present invention and an element group in which the elements are arranged can be realized. The upper wiring electrode 16 can be formed by a known method in combination with a general lithography method or etching method.

  In the examples shown in FIGS. 11 to 19 and FIGS. 21 to 29, when the damascene process is applied to the formation of the lower wiring electrode 17, the wiring and the connection via are simultaneously formed in the laminated film of the low dielectric insulating films having different properties. Any method such as hybrid dual damascene method, dual damascene method in which wiring and connection via are simultaneously formed in a single layer of low dielectric insulating film, and single damascene method in which wiring and connection via are individually formed May be used. Further, a standard technique as a damascene process can be used for specific processes (for example, an insulating film forming process, a groove processing process, a metal filling process, and the like).

  In the examples shown in FIGS. 11 to 19 and FIGS. 21 to 29, the type of the resistance change material 24 deposited inside the opening 23 is not particularly limited, and a resistance change material used for a general resistance change element is used. Can be widely used.

  For example, the resistance change material 24 mainly composed of a metal oxide may be deposited. As the metal oxide, an oxide of at least one element selected from Fe, Ti, W, Ta, and Hf is used. It is preferable because high resistance change characteristics can be realized. That is, in the manufacturing method of the present invention, it is preferable to form the resistance change portion 12 having the oxide of the at least one element as a main component.

Such a resistance change portion 12 can be formed, for example, by depositing a base material containing at least one element and then oxidizing the base material. The base material to be deposited preferably contains, as a main component, an oxide, nitride, simple substance, or a mixture thereof of at least one element. Specifically, for example, a resistance material 12 made of FeO _x1 (3/2 ≧ X1> 4/3) obtained by oxidizing the base material may be used as a base material made of FeO _4/3 . Alternatively, for example, a base material made of TiN may be used, and the resistance change unit 12 made of TiO _X2 N _X3 (0.5 ≦ X2 <2, 0 <X3 <1) obtained by oxidizing the base material may be used. Alternatively, for example, a base material made of TaN may be used, and the resistance change unit 12 made of TaO _X4 N _X5 (1 ≦ X4 <2.5, 0 <X5 <1) obtained by oxidizing the base material may be used.

  In order to deposit the resistance change material 24 on the side surface of the opening 23, the aspect ratio α (α = height of the opening / opening diameter) of the opening 23 is relatively small (for example, α is 5 or less). For this, a film forming method such as a magnetron sputtering method can be used. On the other hand, when the aspect ratio α of the opening 23 is relatively large (for example, α is 10 or more), it is preferable to use a film forming method such as a CVD (chemical vapor deposition) method. For example, when the variable resistance material 24 made of thallium oxide (Ta—O) is deposited, it is possible to meet the condition of the aspect ratio α ≧ 1000 by the CVD method.

  The second electrode 13 that fills the inside of the cylindrical resistance change portion 12 is formed of a film that contacts the inner peripheral surface of the resistance change portion 12 with, for example, a conductive material, You may form by filling the same or different conductive material as the material used for formation.

  In the manufacturing method of the present invention, a step of forming a conductive film having nonlinear electrical characteristics (nonlinear conductive film) on the exposed side surface of the first electrode between the steps (a) and (b) is further provided. May be included. The conductive film to be formed preferably has a Schottky conduction action.

  For example, before depositing the variable resistance material 24 in FIG. 16, a plating layer (plating electrode layer) is formed on the exposed surface of the first electrode 11 into the opening 23 by an electrolytic plating method or the like. A film can be formed. This utilizes the fact that in the electrolytic plating method, the seed does not adhere to the insulating film 14 and the plated electrode layer is formed only on the electrode portion. When the resistance change material 24 made of iron oxide (Fe—O) is deposited (that is, the resistance change portion 12 made of iron oxide), for example, a plated electrode layer made of Au or Pt may be formed. .

  In addition, by using this method, the conductive film 21 to be the first electrode 11 is made of a material (TaN or the like) that is easily subjected to fine processing such as etching, and the contact surface with the resistance change portion 12 is made of Pt or the like. It is also possible to arrange a plated electrode layer.

  Each process shown in FIGS. 11 to 19 and FIGS. 21 to 29 can be performed by applying a known technique, for example, a technique used in a semiconductor element manufacturing process, a thin film forming process, a microfabrication process, or the like. For forming each layer constituting the element, for example, atomic layer deposition (ALD); pulsed laser deposition (PLD), ion beam deposition (IBD), cluster ion beam, and RF, DC, electron cycloton resonance ( Various sputtering methods such as ECR), helicon, inductively coupled plasma (ICP), and counter target; molecular beam epitaxy (MBE), ion plating method and the like can be applied. In addition to the PVD (Physical Vapor Deposition) method, a CVD (Chemical Vapor Deposition) method, a MOCVD (Metalorganic Chemical Vapor Deposition) method, a plating method, a MOD (Metalorganic Decomposition) method, or a sol-gel method may be used. When forming the resistance change portion on the side surface of the opening, it is preferable to use the CVD method because a uniform resistance change portion can be formed.

  For microfabrication of each layer, for example, a method used in a semiconductor device manufacturing process or a magnetic device manufacturing process typified by a magnetoresistive element such as GMR or TMR can be applied. Specifically, for example, a physical or chemical etching method such as an ion milling method, an RIE (Reactive Ion Etching) method, or an FIB (Focused Ion Beam) method may be used. Further, for example, a stepper for forming a fine pattern, a photolithography technique using an EB (Electron Beam) method, or the like may be combined. For example, a CMP method or a cluster ion beam etching method can be used to planarize the surface of the insulating material 22 and the conductive material 25 deposited inside the opening 23.

  When an oxidation treatment is used in combination with the formation of the resistance change portion 12 or the like, the treatment may be performed in an oxidizing atmosphere containing oxygen atoms, molecules, ions, plasma, radicals, or the like. During the oxidation treatment, the atmosphere, temperature, time, and the like may be changed. Known methods such as ECR discharge, glow discharge, RF discharge, helicon, and ICP can be applied to the generation of oxygen plasma and radicals. In the case where nitriding treatment is required for deposition of a base material, the treatment can be performed by the same method as the oxidation treatment.

  Note that an electronic device including the element of the present invention, such as a resistance change memory, can also be manufactured by the above method or a combination of the above method and a known method.

[Electronic device including variable resistance element]
The element of the present invention has two or more states having different electric resistance values. The element changes from one state selected from the two or more states to another state by application of a driving voltage or current. Typically, there are two such states in a device, a high resistance state and a low resistance state, and such a device can be switched from a high resistance state to a low resistance state by application of a driving voltage or current, or a low resistance state. It changes from a state to a high resistance state.

The element of the present invention is also excellent in resistance change characteristics such as a resistance change ratio. The resistance change ratio is a numerical value serving as an index of the resistance change characteristic of the element. Specifically, the resistance value in the high resistance state indicated by the element is R _HIGH , and the resistance value in the low resistance state is R _LOW. Is a value obtained by the following equation (1).
Resistance change ratio = (R _HIGH −R _LOW ) / R _LOW (1)

  A driving voltage or current is applied to the element 1 through the first electrode 11 and the second electrode 13. By applying the driving voltage or current, the state of the element 1 changes from, for example, a high resistance state to a low resistance state, but the state after the change is maintained until the driving voltage or current is applied to the element 1 again. Is done. The state of the element 1 can be changed again (for example, from the low resistance state to the high resistance state) by applying a driving voltage or current to the element 1.

  The driving voltage or current applied to the element 1 does not necessarily have to be the same between when the element 1 is in the high resistance state and when it is in the low resistance state. It may be different depending on the state of 1. That is, the “drive voltage or current” in this specification may be a “voltage or current” that can be changed to another state different from the state when the element 1 is in a certain state.

  Thus, in the element 1, the state of the element exhibiting a specific electric resistance value can be maintained until a drive voltage or current is applied to the element 1. For this reason, a nonvolatile resistance change memory can be constructed by combining the element 1 and a mechanism for detecting the state of the element 1 (that is, a mechanism for detecting the electric resistance value of the element 1). By using two or more elements 1, a memory array can be constructed. In this memory, a bit, for example, “0” for the high resistance state and “1” for the low resistance state may be assigned to each state of the element 1. Since the change of the state of the element 1 can be repeated at least twice, a reliable nonvolatile random access memory can be constructed. Further, by assigning “ON” or “OFF” to each state of the element 1, the element 1 can be applied to a switching element.

  The drive voltage or current applied to the element 1 is preferably pulsed. By making the driving voltage (driving current) into a pulse shape, it is possible to reduce power consumption and improve switching efficiency in an electronic device such as a memory constructed using the element 1. The shape of the pulse is not particularly limited, and may be, for example, at least one shape selected from a sine wave shape, a rectangular wave shape, and a triangular wave shape. The width of the pulse may usually be in the range of several nanoseconds to several milliseconds.

  Of course, the drive voltage or current applied to the element 1 may not be pulsed as long as the above-described state of the resistance change layer 12 can be changed.

  In order to more easily drive the device, the pulse shape is preferably triangular. In order to make the response of the element 1 faster, the shape of the pulse is preferably rectangular, and in this case, a response of several nanoseconds to several microseconds can be achieved. In order to achieve simple driving, reduced power consumption, fast response speed, etc., the pulse shape is a sine wave or a trapezoid with a suitable slope at the rising / falling part of a rectangular wave. It is preferable. A sinusoidal or trapezoidal pulse is suitable when the response speed of the element 1 is about several tens of nanoseconds to several hundreds of microseconds, and a triangular wave-like pulse has a response speed of the element 1 of several tens of microseconds. It is suitable for the case where the second to several milliseconds are set.

  It is preferable to apply a voltage to the element 1. In this case, the element 1 can be miniaturized and an electronic device constructed using the element 1 can be more easily downsized. For example, a potential difference applying mechanism that generates a potential difference between the first electrode 11 and the second electrode 13 is connected to the element 1, and the state of the element 1 is changed by applying a potential difference between both electrodes. Can do. For example, a pulse generator may be used as the potential difference applying mechanism. Hereinafter, a method of changing the state (driving the element 1) by applying a voltage to the element 1 will be described.

  For example, by applying two types of bias voltages (positive bias voltages) such that the potential of the first electrode 11 becomes positive with respect to the potential of the second electrode 13, the element 1 is changed from a low resistance state to a high resistance state. You may change to a resistance state or from a high resistance state to a low resistance state. In particular, when the element 1 has the nonlinear conductive film 18, it is preferable to drive the element 1 by applying the two types of positive bias voltages. More specifically, the element 1 is changed from the low resistance state to the high resistance state by applying the reset voltage of the voltage V1 (V1> 0), and by applying the set voltage of the voltage V2 (V2> V1> 0). The element 1 may be changed from the high resistance state to the low resistance state. Such an operation of the element is called a unipolar operation. In the unipolar operation, the element 1 is reset / set by applying two types of drive voltages having the same polarity. Depending on the configuration of the element 1, the element may be driven by applying two types of bias voltages (negative bias voltages) such that the potential of the first electrode 11 is negative with respect to the potential of the second electrode 13. You can also. In the case of an element having the nonlinear conductive film 18, application of a positive bias voltage or application of a negative bias voltage may be selected according to the electrical characteristics of the conductive film 18.

  Further, for example, the element 1 may be changed from the low resistance state to the high resistance state by applying a positive bias voltage, and the element 1 may be changed from the high resistance state to the low resistance state by applying a negative bias voltage. The application of the positive bias voltage and the application of the negative bias voltage with respect to the change in the state of the element 1 may be reversed. Such an operation of the element is called a bipolar operation. In the bipolar operation, the element 1 is reset / set by applying two types of drive voltages having different polarities. In the case of an element having the non-linear conductive film 18, in order to perform bipolar operation of the element, electrical characteristics that can be applied to both positive and negative bias voltages (for example, a double Schottky type) It is preferable that the conductive film 18 has electrical characteristics exhibiting strong nonlinear conductivity.

  The electrical resistance value of the element 1 is preferably calculated based on the difference between the resistance value (or output current value) of the element 1 and the reference resistance value (or reference output current value) of the reference element. The reference resistance value can be obtained, for example, by preparing a reference element separately from the element to be detected and applying a read voltage (the read voltage will be described later) to the reference element as in the element 1. An example of a circuit configuration for obtaining the electrical resistance value of the element 1 by such a method is shown in FIG.

  In the circuit shown in FIG. 30, an output 93 obtained by amplifying the output 91 from the element 1 by the negative feedback amplifier circuit 92a and an output 96 obtained by amplifying the output 95 from the reference element 94 by the negative feedback amplifier circuit 92b are differential amplifier circuits. Enter in 97. The resistance of the element 1 can be obtained using the output signal 98 obtained from the differential amplifier circuit 97.

  In the case of constructing a resistance change type memory using the element 1, writing information to the element 1 may be performed by applying a driving voltage or current to the element 1, and reading information recorded in the element 1 is, for example, It may be performed by applying a voltage (current) having a magnitude different from that at the time of writing information to the element 1. As an example of a method for writing and reading information, an example of a method for applying a pulsed voltage to the element 1 will be described with reference to FIGS.

  It is assumed that the element 1 is in a low resistance state. When a pulsed positive bias voltage V1 that makes the potential of the first electrode 11 positive with respect to the potential of the second electrode 13 is applied to the element 1, the element 1 changes from the low resistance state to the high resistance state. It changes (reset operation: “RESET” shown in FIG. 31).

Here, the electric resistance value of the element 1 in the high resistance state can be obtained from the current output obtained by applying a positive bias voltage having a magnitude of less than V1 to the element 1. The electric resistance value of the element 1 can also be obtained by applying a negative bias voltage having a magnitude less than V1 to the element 1. These voltages applied to detect the electric resistance value of the element 1 are defined as a read voltage (READ voltage: V _RE ).

  The lead voltage may be pulsed as shown in FIG. By setting the pulsed read voltage, it is possible to reduce power consumption and improve switching efficiency in an electronic device such as a memory constructed using the element 1.

  When the read voltage is applied, the state of the element 1 does not change. Therefore, even when the read voltage is applied a plurality of times, the same electric resistance value can be detected.

  Next, when a pulsed positive bias voltage V2 (V2> V1) is applied, the element 1 changes from the high resistance state to the low resistance state (set operation: “SET” shown in FIG. 31). Here, the electrical resistance value of the element 1 in the low resistance state can be obtained from the current output obtained by applying the read voltage to the element 1.

  In this manner, information can be written to the element 1 and information can be read from the element 1 by applying a pulsed voltage. The magnitude of the output current of the element 1 at the time of reading varies depending on the state of the element 1. Here, if the relatively small output current state (OUTPUT1 in FIG. 31) is “0” and the relatively large output current state (OUTPUT2 in FIG. 31) is “1”, the element 1 is set to the reset voltage. The information “0” is recorded by, and the information “1” is recorded by the set voltage (the information “0” is erased).

  The magnitude of the read voltage is usually preferably in the range of about 1/4 to 1/1000 of the magnitude of the voltage (set voltage and reset voltage) applied during the set operation and the reset operation. Although specific values of the set voltage and the reset voltage depend on the configuration of the element 1, they are usually in the range of about 0.1V to 20V, preferably in the range of about 0.5V to 10V.

  As shown in FIG. 32, by using a pass transistor 35 and arranging two or more elements 1 in a matrix, a nonvolatile random access variable resistance memory array 100 can be constructed.

  In the memory array 100, the bit line 32 is connected to the first electrode 11 of the element 1, and the word line 33 is connected to the second electrode 13 of the element 1. In the case of an element including the strip-shaped first electrode 11 like the element 1 shown in FIG. 1, the first electrode 11 itself may be the bit line 32. In the case of an element including the upper wiring electrode 16 and the lower wiring electrode 17 connected to the second electrode 13 as in the element 1 shown in FIG. 1, at least one wiring electrode may be the word line 33. .

In the memory array 100, a pass transistor 35a connected to one bit line (B _n ) selected from two or more bit lines 32 and one word line (W _n ) selected from two or more word lines 33 are connected. By selecting the selected pass transistor 35b (for example, by selectively turning it on), information is written to the element 1a located at the coordinates (B _n , W _n ), and information is read from the element 1a Is possible. In addition, when reading the information written in the element 1a, for example, the voltage V shown in FIG. 32 that is a voltage corresponding to the electric resistance value of the element 1a may be measured.

A reference element group 37 is arranged in the memory array 100 shown in FIG. 32, and the pass transistor 35c corresponding to the bit line (B ₀ ) connected to the element group 37 is selectively turned on, as shown in FIG. By measuring the voltage V _ref , the difference between the output of the element 1 a and the output of the reference element group 37 can be detected.

  In the memory array 100 shown in FIG. 32, when the element 1 does not have the nonlinear conductive film 18, each element 1 on the array 100 is electrically connected to each other through a non-selected element. However, even if the resistance component through the non-selected element is assumed as the reference element group, and the difference between the output of the selected element 1a and the output of the virtual reference element group is detected as described above, Good. In this method, it is necessary to set the resistance value as the reference element while referring to the state of the element located around the selected element 1a, so that the operation as the memory array is slow, but the configuration is simplified. Can be

  As shown in FIG. 3, when the element 1 is an element multi-valued by the multi-layering of the first electrode 11, for example, an array configuration as shown in FIG. 33 can be realized, and the bit line 32 and the word A memory transistor can be operated by placing a pass transistor in each combination of lines 33.

  The element of the present invention can be applied to nonvolatile semiconductor memories having various forms.

  FIG. 34 is a block diagram showing a configuration of a nonvolatile memory including the element of the present invention. As shown in FIG. 34, the semiconductor memory 200 includes a memory body 201 on a semiconductor substrate. The memory body 201 includes a memory array 202, a row selection circuit / driver 203, a column selection circuit / driver 204, a memory A write circuit 205 for writing information to the array 202, a sense amplifier 206 that detects the amount of current flowing through the selected bit line and determines that the information written in the memory array 202 is “1” or “0”. And a data input / output circuit 207 that performs data input / output processing via a terminal DQ. Further, the semiconductor memory 200 includes an address input circuit 208 that receives an address signal input from the outside of the memory 200 and a control circuit that controls the operation of the memory body 201 based on a control signal input from the outside of the memory 200. 209.

  As shown in FIG. 34, the memory array 202 includes a plurality of word lines WL0, WL1, WL2,... Formed in parallel to each other on a semiconductor substrate, and in parallel with each other in a plane parallel to the main surface of the semiconductor substrate. In addition, above the plurality of word lines, a plurality of bit lines BL0, BL1, BL2,. In the memory array 202, a plurality of memory cells arranged in a matrix so as to correspond to the solid intersections of the word lines WL0, WL1, WL2,... And the bit lines BL0, BL1, BL2,. M111, M112, M113, M121, M122, M123, M131, M132, M133,... (Hereinafter referred to as “memory cells M111, M112,...”) Are arranged, and the memory cells M111, M112,. The device of the present invention is provided.

  The address input circuit 208 receives an address signal from an external circuit (not shown), outputs a row address signal to the row selection circuit / driver 203 based on the address signal, and outputs a column address signal to the column selection circuit / driver 204. Output to. Here, the address signal is a signal indicating the address of a specific memory cell selected from the plurality of memory cells M111, M112,. The row address signal is a signal indicating a row address among the addresses indicated by the address signal, and the column address signal is a signal indicating a column address among the addresses indicated by the address signal.

  In the upper write cycle to the memory array 202, the control circuit 209 outputs a write signal instructing application of a write voltage to the write circuit 205 according to the input data Din input to the data input / output circuit 207. . On the other hand, in the information read cycle, the control circuit 209 outputs a read signal instructing application of the read voltage to the column selection circuit / driver 204.

  The row selection circuit / driver 203 receives the row address signal from the address input circuit 208, selects one of the word lines WL0, WL1, WL2,... According to the received row address signal, and selects the selected word line. A predetermined voltage is applied to.

  The column selection circuit / driver 204 receives a column address signal from the address input circuit 208, selects one of the bit lines BL0, BL1, BL2,... According to the received column address signal, and selects the selected bit line. In contrast, a write voltage or a read voltage is applied.

  When the write circuit 205 receives a write signal from the control circuit 209, the write circuit 205 outputs a signal for instructing application of a voltage to the selected word line to the row selection circuit / driver 203 and also to the column selection circuit / driver 204. On the other hand, a signal instructing application of a write voltage to the selected bit line is output.

The sense amplifier 206 determines the information “1” or “0” by detecting the amount of current flowing through the selected bit line to be read in the information read cycle. The output data DO obtained by the determination is output to an external circuit via the data input / output circuit 207. As shown in FIG. In the case of the device, a multilayered structure stacked in three dimensions can be realized, and for example, an array configuration as shown in FIG. 33 can be realized.

  Next, operation examples of a write cycle for writing information and a read cycle for reading information in the memory 200 shown in FIG. 34 will be described with reference to a timing chart shown in FIG. Here, the variable resistance element included in each memory cell has a non-linear conductive film, and when the element is in a high resistance state, information “1” is assigned, and when the low resistance state is assigned to information “0”, respectively. An example of operation is shown. For convenience of explanation, only the case where information is written to and read from the memory cells M111 and M122 is shown.

  VP in FIG. 35 indicates a pulse voltage necessary for resistance change of an element included in the memory cell. In the example shown in FIG. 35, the voltage VP / 2 is constantly applied to the bit lines BL0 and BL1 and the word lines WL0 and WL1, but the relationship of VP / 2 <threshold voltage Vf is established. Is preferred. The threshold voltage Vf indicates a reset (high resistance) voltage VP or a set (low resistance) voltage VP ′ (> VP). When this relationship is established, leakage current that flows into unselected memory cells, that is, extra current supplied to memory cells that do not need to be written with information, can be suppressed, and the power consumption of the memory 200 can be further reduced. This is because it can proceed. Further, the establishment of this relationship provides an advantage that unintentional writing (generally referred to as “disturb”) to unselected memory cells is suppressed.

  In FIG. 35, tW is the time required for one write cycle (write cycle time), and tR is the time required for one read cycle (read cycle time).

  Here, in the write cycle of the memory cell M111, a pulse voltage VP having a pulse width tP is applied to the bit line BL0, and a voltage having a pulse width tP of 0V (zero volt) is applied to the word line WL0 so as to correspond to the timing. To do. As a result, the resistance change element of the memory cell M111 is increased in resistance, and information “1” is written in the memory cell M111.

  Next, in the write cycle of the memory cell M122, a voltage of 0 V (zero volt) with a pulse width tP is applied to the word line WL1, and a pulse voltage VP ′ (with a pulse width tP) is applied to the bit line BL1 so as to correspond to the timing. VP ′> VP) is applied. As a result, the resistance change element of the memory cell M122 is reduced in resistance, and information “0” is written in the memory cell M122.

  Next, in the read cycle of the memory cell M111, a voltage having a pulse width smaller than the pulse voltage at the time of writing and a value larger than 0 V (zero volts) and smaller than VP / 2 is applied to the bit line BL0. In order to correspond to this timing, a voltage having a pulse width smaller than the pulse voltage at the time of writing and a value larger than VP / 2 and smaller than VP is applied to the word line WL0. Thereby, a current corresponding to the resistance value of the resistance change element of the memory cell M111 is output, and the output current value can be detected to read the information “1”.

  Next, in the read cycle of the memory cell M122, the same voltage as that of the previous read cycle of the memory cell M111 is applied to the word line WL1 and the bit line BL1. As a result, a current corresponding to the resistance value of the resistance change element of the memory cell M122 is output, and the output current value can be detected to read the information “0”.

  Although not shown in this specification, a semiconductor memory is generally provided with a redundant relief memory cell having the same configuration as the memory cell for the purpose of relieving a defective memory cell. In addition, a parity bit memory cell used for error correction may be prepared in a part of the memory array, or a memory array including such a parity bit memory cell may be separately provided. Such a memory cell and memory array may be separately provided in a memory including the element of the present invention, and the resistance change element of the present invention can be used for the memory cell and memory array.

  FIG. 36 is a block diagram showing an example of a configuration of a memory including the element of the present invention.

  As shown in FIG. 36, a semiconductor memory 400 includes a CPU 402, an input / output circuit 403 that performs data input / output processing with an external circuit, a logic circuit 404 that executes a predetermined operation, and an analog signal on a semiconductor substrate 401. Are connected to an analog circuit 405 for processing self-diagnosis, a BIST (Built In Self Test) circuit 406, an SRAM 407, and a BIST circuit 406 and an SRAM 407, and a relief address storage register 408 for storing specific address information It has.

  As shown in FIG. 37, the relief address storage register 408 includes a nonvolatile storage element 409 corresponding to the element of the present invention, a write circuit 410 for writing specific address information to the storage element 409, and a storage element 409. Are provided with a read circuit 411 and a latch circuit 412. It is only necessary that these circuits are connected to the memory array.

  The storage element 409 is connected to a switching unit to the writing circuit 410 side and a switching unit to the reading circuit 411 side.

  The example shown in FIG. 37 shows a configuration in which a memory element 409 is disposed between the first wiring and the second wiring using two-layer wiring. A nonvolatile memory element may be arranged between arbitrary wirings, or a nonvolatile memory element may be arranged between a plurality of wirings as necessary.

  Next, a procedure for writing address information to the relief address storage register 408 will be described with reference to FIGS.

  First, the BIST circuit 406 executes the inspection of the memory block of the SRAM 407 by the diagnosis instruction signal TST. This inspection of the memory block is performed in the manufacturing process of the LSI and in a state where the LSI is mounted on an actual system.

  Next, when a defective bit is detected as a result of the memory block inspection by the BIST circuit 406, the BIST circuit 406 outputs a write data instruction signal WD to the relief address storage register 408. The relief address storage register 408 that has received the write data instruction signal WD stores the address information of the corresponding defective bit in the relief address storage register. Address information is stored by increasing or decreasing the resistance state of the variable resistance element included in the register corresponding to the address information. In this way, address information is written to the relief address storage register 408.

  When the access to the SRAM 407 is executed, the address information written in the relief address storage register 408 is read at the same time. The address information is read by detecting an output current value corresponding to the state of the resistance change element. When the address information read from the relief address storage register 408 matches the address information of the access destination, access to the spare redundant memory cell provided in the SRAM 407 is executed, and information to the memory cell is obtained. Is read or written.

  The realization of such a self-diagnosis function eliminates the need to use an expensive external LSI tester in the inspection process when manufacturing the memory. Further, not only at the time of inspection, but also when a change with time occurs due to actual use, the defective bit can be relieved, and the quality of the memory can be maintained over a long period of time.

  A memory including the element of the present invention can cope with both a case where information is written only once in a manufacturing process and a case where information is rewritten repeatedly after product shipment.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the examples shown below.

Example 1
In Example 1, the variable resistance element 1 having the structure shown in FIG. 1 was produced, and its resistance change characteristics were evaluated. The element 1 was produced based on the method shown in FIGS. Further, the resistance change portion 12 made of an iron oxide (Fe-O), the variable resistance region is formed by oxidizing a base material consisting of Fe ₃ O _4.

First, a strip-like lower wiring electrode 17 containing Cu as a main component is embedded on the surface of the substrate 10 on which the TEOS film (SiO ₂ film) is formed so as to be embedded in the substrate 10 (however, the surface is exposed). Formed. The lower wiring electrode 17 was formed using a standard Cu damascene process, and a Ta / TaN multilayer film was disposed on the surface including the bottom and side surfaces of the lower wiring electrode 17. The wiring width of the lower wiring electrode 17 was 1 μm.

  Next, a laminated body in which a TEOS film as the insulating film 14 and a Pt film as the conductive film 21 were alternately laminated was formed on the substrate 10 and the lower wiring electrode 17. The thickness of the TEOS film was 500 nm, the thickness of the Pt film was 50 nm, and the number of stacked Pt films was 4. The Pt film was produced by a magnetron sputtering method in an argon atmosphere at a pressure of 0.7 Pa with a substrate temperature of 27 ° C. and an applied power of 100 W.

  Next, the stacked body of the insulating film 14 and the conductive film 21 was finely processed to form the first electrode 11 from the conductive film 21. Standard lithography and etching methods are used for microfabrication of the multilayer film, and the shape of the first electrode 11 is a belt-like shape perpendicular to the lower wiring electrode 17 when viewed from the direction perpendicular to the main surface of the substrate 10. did. The wiring width of the first electrode 11 was 5 μm.

  Next, a TEOS film having a thickness of 1500 nm was deposited as an insulating material, and then the deposited insulating material was planarized by CMP to form an insulating layer 22.

  Next, when viewed from a direction perpendicular to the main surface of the substrate 10, a cylindrical opening 23 (0) is provided so that the lower wiring electrode 17 is exposed at a portion where the lower wiring electrode 17 and the first electrode 11 intersect. .4 μmφ) was formed.

Next, Fe ₃ O ₄ was deposited inside the formed opening 23 as a base material of the resistance change material. The deposition of Fe ₃ O ₄ is performed by magnetron sputtering using FeO _0.75 as a target, with the temperature of the substrate 10 being in the range of room temperature to 400 ° C. (mainly 300 ° C.) in an argon atmosphere at a pressure of 0.6 Pa. The power was RF100W. In depositing the base material, the base material was deposited on the side surface of the opening 23, but attention was paid so that the opening 23 was not filled with the base material. The specific resistance of the deposited base material is about 5 to 50 mΩcm (typically 10 mΩcm). The specific resistance value and evaluation methods such as X-ray diffraction, infrared absorption, and Raman spectroscopy are used to determine the specific resistance of the base material. It was confirmed that the material was Fe ₃ O ₄ . Subsequently, the deposited base material is oxidized by heat treatment (300 ° C., 1 minute) in an oxidizing atmosphere, and then the oxidized base material deposited on the bottom surface of the opening 23 and the insulating layer 22 is dry-etched. After removal, a cylindrical resistance change portion 12 made of iron oxide was formed in the opening 23. The film thickness of the resistance change portion 12 was 20 nm. The composition of the resistance change portion 12 was estimated to be FeO _X1 (3/2 ≧ X1> 4/3) from the result of oxidation treatment under the same conditions for the solid film of Fe ₃ O ₄ .

  Next, a Pt / TaN / W laminated film is deposited as the conductive material 25 so as to fill the inside of the opening 23, and the conductive material 25 deposited on the insulating layer 22 is removed by CMP. The plug-shaped second electrode 13 filled in the cylindrical resistance change portion 12 was used. In the laminated film, the thickness of the Pt film was 10 nm, the thickness of the TaN film was 20 nm, and W was deposited so as to fill the remaining space following the deposition of the Pt film and the TaN film.

  Next, a strip-shaped upper wiring electrode 16 extending in the same direction as the direction in which the lower wiring electrode 17 extends was formed of TaN to obtain a resistance change element 1 (sample 1) as shown in FIG. The thickness of the upper wiring electrode 16 was 50 nm, and the wiring width was 5 μm.

  When the electrical characteristics of Sample 1 produced in this way were evaluated, it showed non-linear bias voltage applicability. This is because the iron oxide constituting the resistance change portion 12 is an n-type semiconductor, and the contact between the resistance change portion 12 and the first electrode 11 made of Pt having a high work function is Schottky. It was presumed to be the cause.

Next, a pulse voltage shown in FIG. 31 was applied to Sample 1 and the resistance change ratio was evaluated. The resistance change ratio was evaluated as follows. A positive bias voltage of 1 V as a reset voltage, 2.5 V as a set voltage, and 0.05 V as a read voltage was applied between the first electrode 11 and the lower wiring electrode 17 of Sample 1 using a pulse generator. The pulse width of each voltage is 10 ms (milliseconds), and the electric resistance value of sample 1 after applying the set voltage and the electric resistance value of sample 1 after applying the reset voltage are samples by applying the read voltage. It was obtained from the output current value of 1. One electrical resistance value reflects the high resistance state of sample 1, and the other electrical resistance value reflects the low resistance state of sample 1. Here, the electrical resistance value of Sample 1 obtained in the above-described manner in the high resistance state is R _HIGH , and the electrical resistance value of Sample 1 in the low resistance state is R _LOW, and the resistance change ratio is obtained from the following equation.
[Resistance change ratio] = (R _HIGH -R _LOW ) / R _LOW

As a result of the evaluation, Sample 1 exhibited a resistance change ratio of 10 times or more, a write repetition performance of 1000 times or more, and a holding characteristic (R _High / R _LOW holding characteristic) of 500 hours or more. Note that the write repeatability is a characteristic that evaluates whether or not the set operation and the reset operation are repeated as one cycle, and the retention characteristic is that the elements in the R _High and R _LOW states are held at room temperature. This is a characteristic evaluated by the time during which the change in the resistance value of the element is held within 25% of the initial value.

  The evaluation results are shown in Table 1 below.

  Separately, a positive bias voltage of 1.5 V is applied as a reset voltage, a negative bias voltage of 2.5 V is applied as a set voltage, and a positive bias voltage of 0.05 V is applied as a read voltage, so that the bipolar operation of Sample 1 can be verified. went. The pulse width of each voltage was 100 ns (nanoseconds). With this operation, the resistance change ratio of sample 1 was obtained in the same manner as described above. Sample 1 exhibited a resistance change ratio of 10 times or more, a write repetition performance of 1000 times or more, and a holding characteristic of 500 hours or more. It was.

(Example 2)
In Example 2, the variable resistance element 1 (sample 2) having the structure shown in FIG. 1 was used in the same manner as in Example 1 except that a TaN film was used instead of the Pt film as the first electrode 11 (conductive film 21). ) Was produced.

  The TaN film is formed by a magnetron sputtering method using Ta as a target in a nitrogen-argon mixed atmosphere at a pressure of 0.1 Pa (nitrogen: argon (volume ratio) = about 4: 1) at a substrate temperature of 0 to 400 ° C. It was made into the range (mainly 350 degreeC), and applied electric power was made into DC4kW.

  When the resistance change ratio, the write repetition performance, and the retention characteristic of Sample 2 were evaluated in the same manner as in Example 1, the resistance change ratio of Sample 2 was 10 times or more, the write repetition performance of 1000 times or more, and 500 hours or more. The retention characteristics were shown.

  The evaluation results are shown in Table 2 below.

(Example 3)
In Example 3, the variable resistance element 1 (sample) having the structure shown in FIG. 1 was used in the same manner as in Example 1 except that the variable resistance part 12 was made of tantalum oxide (Ta—O) instead of iron oxide. 3) was produced.

  The resistance change portion 12 was formed by depositing tantalum oxide inside the opening 23. Tantalum oxide has a substrate temperature of 20 to 20 in an oxygen-argon mixed atmosphere with a pressure of 0.2 to 5 Pa (oxygen flow ratio of 0.1 to 10% by volume) by an RF magnetron sputtering method using Ta as a target. The deposition was performed in a range of 400 ° C. (mainly 300 ° C.) and an applied power of 150 to 300 W. The film thickness of the resistance change portion 12 formed by this deposition was 20 nm. Moreover, the composition of the resistance change portion 12 is about 0.5 to 0.7 in terms of oxygen content (O / (Ta + O)) from the result of evaluating the composition of the Ta oxide deposited on the flat plate under the same conditions. It was estimated that.

  When the resistance change ratio, the write repetition performance, and the retention characteristics of Sample 3 were evaluated in the same manner as in Example 1, the resistance change ratio of Sample 3 was 10 times or more, the write repetition performance of 1000 times or more, and 500 hours or more. The retention characteristics were shown.

  The evaluation results are shown in Table 3 below.

  Separately, a positive bias voltage of 1.5 V is applied as a reset voltage, a negative bias voltage of 2.5 V is applied as a set voltage, and a positive bias voltage of 0.05 V is applied as a read voltage, so that the bipolar operation of Sample 3 can be verified. went. The pulse width of each voltage was 100 ns (nanoseconds). By this operation, the resistance change ratio of sample 3 was obtained in the same manner as described above. Sample 3 showed a resistance change ratio of 10 times or more, a write repetition performance of 1000 times or more, and a holding characteristic of 500 hours or more. It was.

Example 4
In Example 4, the variable resistance element 1 (sample) having the structure shown in FIG. 1 was used in the same manner as in Example 2 except that the variable resistance part 12 was made of tantalum oxide (Ta—O) instead of iron oxide. 4) was produced.

  The resistance change portion 12 was formed by depositing TaN as a base material of the resistance change material in the opening 23 and then oxidizing the deposited TaN.

  TaN, which is a base material, has a substrate temperature of 0 to 0 in a nitrogen-argon mixed atmosphere (nitrogen: argon (volume ratio) = approximately 4: 1) at a pressure of 0.1 Pa by a magnetron sputtering method using Ta as a target. The temperature was 400 ° C. (mainly 350 ° C.) and the applied power was DC 4 kW.

  Next, the deposited TaN was oxidized by plasma oxidation (250 ° C., 60 seconds) to form a resistance change portion 12 made of thallium oxide. The film thickness of the formed resistance change portion 12 was 1 to 5 nm. Further, the composition of the resistance change portion 12 is estimated to be about 0.5 to 0.7 in terms of oxygen content (O / (Ta + O)) from the result of oxidation treatment under the same conditions for the solid film of TaN. It was.

  When the resistance change ratio, the write repetition performance, and the retention characteristics of Sample 4 were evaluated in the same manner as in Example 1, the resistance change ratio of Sample 4 was 10 times or more, the write repetition performance of 1000 times or more, and 500 hours or more. The retention characteristics were shown.

  The evaluation results are shown in Table 4 below.

(Example 5)
In Example 5, the resistance change element 1 (samples 5-1 to 5-3) having the structure shown in FIG. 1 was changed by changing the material constituting the first electrode 11 and the material constituting the resistance change portion 12. ) And its resistance change characteristics were evaluated. Each sample of Samples 5-1 to 5-3 was fabricated in the same manner as in Example 1.

The combination of the material which comprises the 1st electrode 11 in each sample, and the material which comprises the resistance change part 12 is as follows.
----------------------------------
Sample 5-1 TiN (first electrode) Ti-O (resistance change portion)
Sample 5-2 TaN (first electrode) WO (resistance change portion)
Sample 5-3 Pt (first electrode) Hf-O (resistance change portion)
----------------------------------

  The TiN film is formed by a magnetron sputtering method using Ti as a target in a nitrogen-argon mixed atmosphere (nitrogen: argon (volume ratio) = about 4: 1) at a pressure of 0.1 Pa in a substrate temperature range of 20 to 400 ° C. (Mainly 150 ° C.), and the applied power was DC4 kW.

  The TaN film is formed by a magnetron sputtering method using Ta as a target in a nitrogen-argon mixed atmosphere at a pressure of 0.1 Pa (nitrogen: argon (volume ratio) = approximately 4: 1) in a range of 0 to 400 ° C. of the substrate temperature. (Mainly 350 ° C.), and the applied power was DC4 kW.

  The Pt film was produced by a magnetron sputtering method in an argon atmosphere at a pressure of 0.7 Pa with a substrate temperature of 27 ° C. and an applied power of 100 W.

Ti-O (titanium oxide) is obtained by a magnetron sputtering method using Ti as a target in an oxygen-argon mixed atmosphere at a pressure of 0.2 to 5 Pa (0.1 to 10% by volume as an oxygen flow ratio). The substrate temperature was set in the range of 20 to 400 ° C. (mainly 300 ° C.), and the applied power was RF150-300W. The composition of the deposited titanium oxide was estimated to be TiO _X2 (0.5 ≦ X2 <2) from the result of evaluating the composition of the titanium oxide deposited on the flat plate under the same conditions.

W—O (tungsten oxide) is obtained by a magnetron sputtering method using W as a target in an oxygen-argon mixed atmosphere at a pressure of 0.2 to 5 Pa (0.1 to 10% by volume as an oxygen flow ratio). The substrate temperature was set in the range of 20 to 400 ° C. (mainly 300 ° C.), and the applied power was RF150-300W. The composition of the deposited tungsten oxide was estimated to be WO _X6 (0.5 ≦ X6 <3) from the result of evaluating the composition of the tungsten oxide deposited on the flat plate under the same conditions.

Hf-O (hafnium oxide) is obtained by a magnetron sputtering method using Hf as a target in an oxygen-argon mixed atmosphere at a pressure of 0.2 to 5 Pa (0.1 to 10% by volume as an oxygen flow ratio). The substrate temperature was set in the range of 20 to 400 ° C. (mainly 300 ° C.), and the applied power was RF150-300W. The composition of the deposited hafnium oxide was estimated to be HfO _X7 (0.5 ≦ X7 <2) from the result of evaluating the composition of the hafnium oxide deposited on the flat plate under the same conditions.

  When the resistance change ratio, the write repetition performance, and the retention characteristics of Samples 5-1 to 5-3 were evaluated in the same manner as in Example 1, all of Samples 5-1 to 5-3 had a resistance change of 10 times or more. The ratio, the repetition performance of writing over 100 times, and the retention characteristics over 100 hours were shown.

  The evaluation results are shown in Table 5 below.

(Example 6)
Sample 1 produced in Example 1 was arranged in a matrix (8 × 8) to construct a 64-bit memory array, and the operation of the memory was checked. It could be confirmed.

  ADVANTAGE OF THE INVENTION According to this invention, the resistance change element which has a new structure which can respond to further miniaturization and high integration of an element can be provided, reducing the load of the formation process of a resistance change part.

  The variable resistance element of the present invention can be applied to various electronic devices. Examples of the electronic device include nonvolatile memories, switching elements, sensors, and image display devices used in information communication terminals and digital home appliances. .

It is sectional drawing which shows typically an example of the resistance change element of this invention. It is the top view which looked at the resistance change element shown in FIG. 1 from the upper surface. It is sectional drawing which shows typically another example of the variable resistance element of this invention. It is sectional drawing which shows typically another example of the variable resistance element of this invention. It is the top view which looked at the resistance change element shown in FIG. 4 from the upper surface. It is sectional drawing which shows typically the state which arranged the 2 or more resistance change element of this invention in the array form. It is the top view which looked at the state of the arrangement | sequence shown in FIG. 6 from the upper surface of the element. It is a top view which shows typically the state which arranged the 2 or more resistance change element of this invention in matrix form (matrix form). It is a figure which shows the equivalent circuit of the state of the arrangement | sequence shown in FIG. It is a top view which shows typically another example of the variable resistance element of this invention. It is process drawing which shows typically an example of the manufacturing method of the resistance change element of this invention. FIG. 12 is a diagram showing a step that follows the step of FIG. 11. FIG. 13 is a diagram showing a step that follows the step of FIG. 12. FIG. 14 is a diagram showing a step that follows the step of FIG. 13. FIG. 15 is a diagram showing a step that follows the step of FIG. 14. . FIG. 16 is a diagram showing a step that follows the step of FIG. 15. FIG. 17 is a diagram showing a step that follows the step of FIG. 16. FIG. 18 is a diagram showing a step that follows the step of FIG. 17. FIG. 19 is a diagram showing a step that follows the step of FIG. 18. It is sectional drawing which shows typically another example of the variable resistance element of this invention. It is process drawing which shows typically another example of the manufacturing method of the resistance change element of this invention. FIG. 22 is a diagram showing a step that follows the step of FIG. 21. FIG. 23 is a diagram showing a step that follows the step of FIG. 22. FIG. 24 is a diagram showing a step that follows the step of FIG. 23. FIG. 25 is a diagram showing a step that follows the step of FIG. 24. FIG. 26 is a diagram showing a step that follows the step of FIG. 25. FIG. 27 is a diagram showing a step that follows the step of FIG. 26. FIG. 28 is a diagram showing a step that follows the step of FIG. 27. FIG. 29 is a diagram showing a step that follows the step of FIG. 28. It is a figure for demonstrating an example of the reading method of the information in the resistance change element of this invention. It is a figure for demonstrating an example of the writing and reading-out method of the information in the resistance change element of this invention. It is a schematic diagram which shows an example of a memory array provided with the resistance change element of this invention. It is a schematic diagram which shows an example of a memory array provided with the resistance change element of this invention. It is a block diagram which shows typically an example of a structure of a memory provided with the resistance change element of this invention. FIG. 35 is a timing chart showing an operation example of the memory shown in FIG. 34. FIG. It is a block diagram which shows typically another example of a structure of a memory provided with the resistance change element of this invention. FIG. 37 is a block diagram schematically showing an example of a configuration of a relief address storage register of the memory shown in FIG. 36.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Resistance change element 2 Element group 3 Element group 10 Board | substrate 11 1st electrode 12 Resistance change part 13 2nd electrode 14 Insulating film 15 Laminated body 16 Upper wiring electrode 17 Lower wiring electrode 18 Nonlinear conductive film 21 Conductive film 22 Insulating layer 23 Opening 24 Resistance change material 25 Conductive material 32 Bit line 33 Word line 35, 35a, 35b, 35c Pass transistor 37 Reference element group 91 Output (from element 1) 92a, 92b Negative feedback amplifier circuit 93 (Negative) Output 94 (from feedback amplifier 92a) Reference element 95 Output 96 (from reference element 94) Output 96 (From negative feedback amplifier 92b) 97 Differential amplifier 98 Output signal (From differential amplifier 97) 100 Memory Array 200 Semiconductor memory 201 Memory body 202 Memory array 203 Row selection circuit / driver 2 4 column selection circuit / driver 205 write circuit 206 sense amplifier 207 data input-output circuit 208 address input circuit 209 control circuit 400 semiconductor memory 401 a semiconductor substrate 402 CPU
403 I / O circuit 404 Logic circuit 405 Analog circuit 406 BIST circuit 407 SRAM
408 Relief address storage register 409 Non-volatile memory element 410 Write circuit 411 Read circuit 412 Latch circuit

Claims (31)

A substrate, a first electrode and a second electrode disposed on the substrate, and a resistance change portion disposed between the first and second electrodes,
There are two or more states with different electrical resistance values between the first and second electrodes,
A resistance change element that changes from one state selected from the two or more states to another state by applying a driving voltage or current to the resistance change unit via the first and second electrodes. And
A stacked body having a stacked structure of the first electrode and the insulating film is disposed on the substrate;
The variable resistance portion is in contact with the stacked body such that the side surfaces thereof are in contact with both side surfaces of the first electrode and the insulating film,
The resistance change element and the second electrode are resistance change elements in contact with each other on each side surface.   The resistance change element according to claim 1, wherein a stacking direction of the first electrode and the insulating film in the stacked structure is perpendicular to a main surface of the substrate.   The variable resistance element according to claim 1, wherein the first electrode is sandwiched between the insulating films in the stacked structure.   2. The variable resistance element according to claim 1, wherein a side surface of the first electrode that contacts the variable resistance portion and a side surface of the insulating film that contacts the variable resistance portion are on the same plane. The laminated body has a laminated structure in which two or more first electrodes and the insulating film are alternately laminated,
The resistance change element according to claim 1, wherein at least two electrodes selected from the two or more first electrodes are in contact with the common resistance change unit.   The variable resistance element according to claim 5, wherein all of the two or more first electrodes are in contact with the common variable resistance portion.   The resistance change element according to claim 5, wherein side surfaces of the at least two electrodes that are in contact with the resistance change portion are on the same plane.   The variable resistance element according to claim 1, wherein the variable resistance portion has a columnar shape extending in a direction perpendicular to a main surface of the substrate. The resistance change portion is a cylindrical shape having a direction perpendicular to the main surface of the substrate as a central axis direction,
The resistance change element according to claim 1, wherein the first electrode is in contact with the outer peripheral surface of the resistance change portion, and the second electrode is in contact with the inner peripheral surface of the resistance change portion. The first electrode has a through hole formed by a peripheral surface having a shape corresponding to the outer peripheral surface of the resistance change portion,
The resistance change element according to claim 9, wherein the resistance change portion is disposed in the through hole. The first electrode has a notch portion having a side surface having a shape corresponding to the outer peripheral surface of the resistance change portion,
The resistance change element according to claim 9, wherein the resistance change portion is disposed so as to be fitted to the notch portion.   The variable resistance element according to claim 10, wherein the first electrode has a flat plate shape having a main surface parallel to the main surface of the substrate.   The variable resistance element according to claim 9, wherein the variable resistance portion has a portion in contact with the second electrode over an entire inner peripheral surface thereof.   10. The variable resistance element according to claim 9, wherein the second electrode has a columnar shape having a peripheral surface corresponding to an inner peripheral surface of the variable resistance portion, and is disposed inside the variable resistance portion.   The resistance change element according to claim 9, wherein the second electrode is disposed so as to fill the inside of the resistance change portion.   The resistance change element according to claim 9, wherein a strip-shaped wiring electrode electrically connected to the second electrode is further disposed above and / or below the resistance change portion.   The first electrode and the wiring electrode have a strip shape extending on a plane parallel to the main surface of the substrate, and are orthogonal to each other when viewed from a direction perpendicular to the main surface of the substrate. The resistance change element described.   2. The variable resistance element according to claim 1, wherein a conductive film having nonlinear electrical characteristics is formed in a portion in contact with the variable resistance portion in at least one electrode selected from the first electrode and the second electrode. .   The resistance change element according to claim 18, wherein the conductive film has a Schottky conduction function.   2. The resistance change portion is mainly composed of an oxide of at least one element selected from iron (Fe), titanium (Ti), tungsten (W), tantalum (Ta), and hafnium (Hf). The resistance change element according to 1.   A resistance change type memory comprising the resistance change element according to claim 1 as a memory element.   The resistance change type memory according to claim 21, wherein the two or more elements are arranged in a matrix. It is a manufacturing method of the resistance change element according to claim 1,
A step (a) of forming a first laminated body having a laminated structure of a first electrode and an insulating film on a substrate, the first electrode and a side surface of the insulating film being exposed;
A step (b) of forming a resistance change portion so that its side surface is in contact with the side surfaces of both the first electrode and the insulating film;
A step (c) of forming a second electrode such that the side surface of the resistance change portion is in contact with the side surface of the resistance change portion while sandwiching the resistance change portion together with the first electrode. Production method. In the step (a),
Forming the first laminated body having a laminated structure in which two or more of the first electrodes and the insulating film are alternately laminated;
In the step (b),
24. The method of manufacturing a resistance change element according to claim 23, wherein the resistance change portion is formed such that its side surface is in contact with the side surface of at least two electrodes selected from the two or more first electrodes. In the step (a),
Forming a second stacked body having a stacked structure of the first electrode and the insulating film on the substrate;
24. The resistor according to claim 23, wherein an opening is formed in the formed second stacked body so that side surfaces of the first electrode and the insulating film are exposed, thereby forming the first stacked body. A manufacturing method of a change element. In the step (a),
26. The method of manufacturing a resistance change element according to claim 25, wherein the columnar opening that extends in a direction perpendicular to the main surface of the substrate is formed in the second stacked body. In the step (b),
Forming the tubular resistance change portion having an outer peripheral surface having a shape corresponding to the inner peripheral surface of the opening in the formed opening,
27. The resistance according to claim 26, wherein in the step (c), the columnar second electrode having a peripheral surface corresponding to an inner peripheral surface of the resistance change portion is formed inside the formed resistance change portion. A manufacturing method of a change element.   24. The method of manufacturing a resistance change element according to claim 23, further comprising a step of forming a strip-shaped wiring electrode electrically connected to the second electrode. Between the steps (a) and (b),
24. The method of manufacturing a resistance change element according to claim 23, further comprising a step of forming a conductive film having non-linear electrical characteristics on the exposed side surface of the first electrode.   30. The method of manufacturing a resistance change element according to claim 29, wherein the conductive film has a Schottky conduction action. In the step (b),
Forming the variable resistance portion mainly composed of an oxide of at least one element selected from iron (Fe), titanium (Ti), tungsten (W), tantalum (Ta), and hafnium (Hf). Item 24. The method of manufacturing a resistance change element according to Item 23.

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