JP2013201269A - Molecular memory and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molecular memory, in which variations in characteristics between memory cells are small, and a manufacturing method thereof.SOLUTION: A molecular memory according to an embodiment includes: first wiring that is made of a first conductive material and extends in a first direction; second wiring that is made of a second conductive material different from the first conductive material and extends in a second direction orthogonal to the first direction; and a resistance change type molecular chain disposed between the first wiring and the second wiring. An area, which opposes a center part in a widthwise direction of the second wiring, of a surface on a second wiring side of the first wiring is positioned closer to the second wiring than an area, which opposes an end part in the widthwise direction of the second wiring, of the surface.

Description

  Embodiments described herein relate generally to a molecular memory and a method for manufacturing the same.

  Conventionally, in a nonvolatile memory device such as a NAND flash memory, the recording density has been improved by miniaturizing a memory cell. However, miniaturization of memory cells is approaching the limit due to limitations of lithography technology. Therefore, research on molecular memory using resistance change type molecular chains as memory elements is underway. The resistance change type molecular chain is a molecular chain whose electric resistance value changes when an electric signal such as voltage or current is input, and since its size is small, there is a possibility that the memory cell can be greatly miniaturized. In order to commercialize such a molecular memory, it is important to reduce the variation in characteristics between memory cells.

JP 2008-294166 A

  An object of the present invention is to provide a molecular memory having a small variation in characteristics between memory cells and a method for manufacturing the same.

  The molecular memory according to the embodiment includes a first wiring made of a first conductive material, extending in a first direction, and a second conductive material different from the first conductive material, and the first direction. 2nd wiring extended in the 2nd direction which crosses, and a resistance change type molecular chain arranged between the 1st wiring and the 2nd wiring. Of the surface of the first wiring on the second wiring side, the region facing the central portion in the width direction of the second wiring is more than the region facing the end portion in the width direction of the second wiring. Located on the side.

  The method for manufacturing a molecular memory according to the embodiment includes a first conductive film made of a first conductive material, a sacrificial film, and a second conductive film made of a second conductive material different from the first conductive material. The step of laminating in this order, and the upper layer portion of the first conductive film, the sacrificial film, and the second conductive film are selectively removed to form a plurality of first stacked bodies extending in the first direction. Side etching the upper layer portion of the first conductive film to make the width of the upper layer portion smaller than the width of the second conductive film; and embedding a first insulating film between the first stacked bodies; The first insulating film, the second conductive film, the sacrificial film, and the first conductive film are selectively removed, and a plurality of second stacked layers extending in a second direction intersecting the first direction. Forming a body; removing the sacrificial film to form a void; and Disposing a resistance variable molecular chain therein, embedding a second insulating film between the second stacked bodies in which the variable resistance molecular chain is disposed, and the arrayed along the first direction Forming a third conductive film extending in the first direction so as to be commonly connected to the second conductive film.

1 is a perspective view illustrating a molecular memory according to a first embodiment. 1 is a cross-sectional view illustrating a molecular memory according to a first embodiment. It is a figure which illustrates the resistance change type molecular chain in 1st Embodiment. (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). (A)-(c) is process drawing which illustrates the manufacturing method of the molecular memory which concerns on 1st Embodiment, (a) is a top view, (b) is AA shown to (a). It is sectional drawing by a line, (c) is sectional drawing by the BB 'line shown to (a). It is sectional drawing which illustrates the molecular memory which concerns on a comparative example. FIG. 6 is a perspective view illustrating a molecular memory according to a second embodiment. It is sectional drawing which illustrates the molecular memory which concerns on 2nd Embodiment. It is sectional drawing which illustrates the molecular memory which concerns on 3rd Embodiment. FIG. 6 is a circuit diagram illustrating a molecular memory according to a third embodiment. FIG. 10 is a perspective view illustrating a molecular memory according to a fourth embodiment. It is a figure which illustrates the general formula of the resistance change type molecular chain which concerns on a modification. (A)-(f) is a figure which illustrates the molecular unit which can comprise the molecule | numerator which (pi) conjugated system extended in the one-dimensional direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the first embodiment will be described.
FIG. 1 is a perspective view illustrating a molecular memory according to this embodiment.
FIG. 2 is a cross-sectional view illustrating a molecular memory according to this embodiment.
FIG. 3 is a diagram illustrating a resistance variable molecular chain in the present embodiment.
In order to make the drawing easier to see, only the conductive portion is shown in FIG. 1, and the insulating portion is not shown.

  As shown in FIGS. 1 and 2, in the molecular memory 1 according to the present embodiment, an interlayer insulating film 10 is provided on a silicon substrate (not shown), and a wiring layer 11 and a memory layer are formed thereon. 12 and the wiring layer 13 are laminated in this order. Hereinafter, this stacking direction is referred to as “Z direction”. In the wiring layer 11, a plurality of wirings 21 extending in one direction (hereinafter referred to as “Y direction”) are periodically arranged. In the wiring layer 13, a plurality of wirings 22 that intersect with the Y direction, for example, extend in a direction orthogonal to the Y direction (hereinafter referred to as “X direction”) are periodically arranged. The X direction, the Y direction, and the Z direction are orthogonal to each other. The wiring 21 and the wiring 22 are formed of different conductive materials. The wiring 21 is made of, for example, molybdenum (Mo), and the wiring 22 is made of, for example, tungsten (W).

  And, in the upper surface 21 a of the wiring 21, that is, the surface on the wiring 22 side, the region 21 b facing the central portion in the width direction (Y direction) of the wiring 22 is more than the region 21 c facing both ends in the width direction of the wiring 22. , Located above, that is, on the wiring 22 side. The region 21 c also faces the space between the wirings 22. Thus, a convex portion 21 d that protrudes toward the center in the width direction of the wiring 22 is formed on the upper surface 21 a of the wiring 21. The convex portions 21d are periodically arranged at the same period as the arrangement period of the wirings 22 along the direction (Y direction) in which the wirings 21 extend. The convex portion 21 d is formed over the entire length in the width direction of the wiring 21.

  On the other hand, of the lower surface 22a of the wiring 22, that is, the surface on the wiring 21 side, the region 22b facing the wiring 21 is located below the region 22c facing the space between the wirings 21, that is, on the wiring 21 side. ing. Thus, a convex portion 22 d that protrudes toward the wiring 21 is formed on the lower surface 22 a of the wiring 22. The convex portions 22d are periodically arranged at the same period as the arrangement period of the wirings 21 along the direction (X direction) in which the wirings 22 extend. Further, the convex portion 22 d is formed over the entire length in the width direction of the wiring 22.

  A gap 30 is formed in the closest portion between the wiring 21 and the wiring 22, that is, in the region immediately below the convex portion 22d. Thereby, in the memory layer 12, the plurality of voids 30 are arranged in a matrix along the X direction and the Y direction. In each gap 30, an organic molecular layer 32 including a plurality of resistance variable molecular chains 31 is provided. The resistance change type molecular chain 31 is a molecule that changes an electric resistance value when an electric signal such as voltage or current is inputted. Each organic molecular layer 32 includes, for example, about several tens to several hundreds of resistance change type molecular chains 31.

  As shown in FIG. 3, the resistance-change molecular chain 31 is, for example, 4- [2-amino-5-nitro-4- (phenethylenyl) phenethylenyl] benzenethiol, and one end thereof has a thiol group (R-SH). ) Is provided. The sulfur atom (S) of the thiol group is easily bonded to the tungsten atom (W). On the other hand, the resistance variable molecular chain 31 does not include a group that easily binds to a molybdenum atom (Mo). For this reason, the resistance variable molecular chain 31 is easier to bond with tungsten than with molybdenum.

  Therefore, the resistance change type molecular chain 31 is bonded to the wiring 22 made of tungsten, but is not bonded to the wiring 21 made of molybdenum. As a result, each resistance variable molecular chain 31 has one end coupled to the lower surface of the convex portion 22d of the wiring 22, that is, the region 22b, and the direction from the wiring 22 toward the wiring 21 (Z Direction). The length of the resistance variable molecular chain 31 is, for example, about 2 nm. However, the other end portion of the resistance variable molecular chain 31 does not reach the wiring 21 and is separated from the wiring 21 with a gap of, for example, about 1 nm.

In the molecular memory 1, an inter-wiring insulating film 35 is provided so as to embed the wiring 21, the wiring 22, and the organic molecular layer 32. The interlayer insulating film 10 and the inter-wiring insulating film 35 are formed of an insulating material such as silicon oxide, alumina, or silicon nitride, for example.
The width direction end of the wiring 22 refers to, for example, about 10 to 30% of the width of the wiring 22. Therefore, the length of the convex portion 21 d in the Y direction is about 40 to 80% of the width of the wiring 22. In one example, the widths of the wirings 21 and 22 are 10 nm, the length of the convex portion 21d in the Y direction is 6 nm, and the height of the convex portion 21d is 4 to 5 nm.

Next, a method for manufacturing the molecular memory 1 according to this embodiment will be described.
4 (a)-(c), FIG. 5 (a)-(c), FIG. 6 (a)-(c), FIG. 7 (a)-(c), FIG. 8 (a)-(c), FIGS. 9A to 9C, FIGS. 10A to 10C, and FIGS. 11A to 11C are process diagrams illustrating the method for manufacturing the molecular memory according to this embodiment.
4A to 4C show the same process. 4A is a plan view, FIG. 4B is a cross-sectional view taken along the line AA ′ shown in FIG. 4A, and FIG. 4C is a cross-sectional view taken along line B- shown in FIG. It is sectional drawing by a B 'line. The same applies to FIGS. 5A to 11C.

  First, as shown in FIGS. 4A to 4C, an interlayer insulating film 10 made of an insulating material such as silicon oxide or alumina is formed on a silicon substrate (not shown). Next, a conductive material, for example, molybdenum is deposited, and a conductive film 21 m is formed on the interlayer insulating film 10. Next, a sacrificial film 40 is formed by depositing a material that can be removed by wet etching in a later step, for example, silicon oxide, aluminum oxide, or silicon nitride. Next, a conductive material different from molybdenum, for example, tungsten is deposited to form a conductive film 22m. In this manner, a stacked body in which the interlayer insulating film 10, the conductive film 21m, the sacrificial film 40, and the conductive film 22m are stacked in this order from the lower layer side is formed on the silicon substrate.

  Next, as shown in FIGS. 5A to 5C, the conductive film 22m and the sacrificial film 40 are selectively removed by using a lithography technique and an anisotropic etching technique to form a line shape extending in the X direction. To process. Subsequently, the upper layer portion 21u of the conductive film 21m is selectively removed and processed into a line extending in the X direction. Thus, the upper layer portion 21u of the conductive film 21m, the sacrificial film 40, and the conductive film 22 are stacked in this order, and a plurality of stacked bodies 41 extending in the X direction are formed. A portion other than the upper layer portion 21u in the conductive film 21m, that is, a portion remaining in a planar shape without being processed into a line shape is defined as a planar portion 21p.

  Next, for example, isotropic etching is performed to side-etch the upper layer portion 21u. As a result, the width of the upper layer portion 21u becomes narrower than the widths of the conductive film 22m and the sacrificial film 40. At this time, the end portion of the conductive film 22m may be slightly etched and damaged. For example, the lower surfaces of both ends in the width direction (Y direction) of the conductive film 22 may be inclined. However, this damage is not shown.

  Next, as shown in FIGS. 6A to 6C, an insulating material different from the sacrificial film 40, for example, silicon oxide, aluminum oxide, or silicon nitride is deposited to obtain a plane of the conductive film 21 m. An insulating film 35a is formed on the portion 21p so as to bury the stacked body 41. Next, a planarization process such as CMP (chemical mechanical polishing) is performed using the conductive film 22m as a stopper to planarize the upper surface of the insulating film 35a.

  Next, as shown in FIGS. 7A to 7C, the conductive film 22m, the sacrificial film 40, and the conductive film 21m are selectively removed using a lithography technique and an anisotropic etching technique. Thereby, a plurality of stacked bodies 42 including the conductive film 21m, the sacrificial film 40, the conductive film 22m, and the insulating film 35a and extending in the Y direction are formed. At this time, the stacked body 41 including the upper layer portion 21u of the conductive film 21m, the sacrificial film 40, and the conductive film 22 is divided along both the X direction and the Y direction, and a plurality of island-shaped portions arranged in a matrix. It becomes. The insulating film 35a is also divided along both the X direction and the Y direction, and is disposed between the stacked bodies 41 adjacent in the Y direction. Furthermore, the planar portion 21p of the conductive film 21m is divided into a plurality of line-shaped portions extending in the Y direction. Thereby, the conductive film 21m becomes a plurality of wirings 21. That is, in each stacked body 42, the wiring 21 is provided below the stacked body 42, and the stacked body 41 and the insulating films 35 a are alternately arranged on the wiring 21 along the Y direction.

  Next, as shown in FIGS. 8A to 8C, for example, wet etching is performed to remove the sacrificial film 40 (see FIGS. 7B and 7C). Thereby, the air gap 30 is formed in the space after the sacrificial film 40 is removed. The wiring 21 is disposed below the gap 30, the conductive film 22m is disposed above, the insulating film 35a is disposed on both sides in the Y direction, and both sides in the X direction are open.

  Next, a chemical solution including the resistance change type molecular chain 31 (see FIG. 3) is permeated into the gap 30. Thereby, the resistance variable molecular chain 31 is arranged in the gap 30. Since the thiol group of the resistance variable molecular chain 31 is bonded to a tungsten atom (W) contained in the conductive film 22m, one end of the resistance variable molecular chain 31 is bonded to the lower surface of the conductive film 22m. On the other hand, the resistance variable molecular chain 31 is not bonded to the wiring 21 made of molybdenum. Next, a treatment such as drying is performed to remove the liquid contained in the chemical liquid from the gap 30. As a result, an organic molecular layer 32 is formed at each closest portion between the wiring 21 and the conductive film 22m. Each organic molecular layer 32 includes, for example, several tens to several hundreds of resistance variable molecular chains 31.

  Next, as shown in FIGS. 9A to 9C, an insulating material such as silicon oxide, alumina, or silicon nitride is deposited to form an insulating film 35b. Next, a planarization process such as CMP is performed using the conductive film 22m as a stopper to planarize the upper surface of the insulating film 35b. Thereby, the insulating film 35b is removed from the upper surface of the conductive film 22m, and the insulating film 35b is embedded between the stacked bodies 42. At this time, the insulating material hardly penetrates into the gap 30 and remains as it is. Accordingly, the insulating material does not enter between the resistance change type molecular chains 31 formed in the gap 30.

  Next, as shown in FIGS. 10A to 10C, for example, molybdenum is deposited to form a conductive film 22n on the entire surface. The conductive film 22n is in contact with the conductive film 22m.

  Next, as shown in FIGS. 11A to 11C, the conductive film 22n is selectively removed using a lithography technique and an etching technique. Thereby, the conductive film 22n is processed into a plurality of lines extending in the X direction. At this time, the conductive film 22n is left so as to pass through the region immediately above the conductive film 22m. Thereby, the conductive film 22n is commonly connected to the conductive films 22m arranged in a line along the X direction. Next, an insulating material (not shown) is deposited so as to embed the conductive film 22n processed into a line shape. In this way, the molecular memory 1 according to this embodiment is manufactured.

  In the molecular memory 1, the conductive film 22m and the conductive film 22n become the wiring 22 extending in the X direction. At this time, the conductive film 22 m becomes the convex portion 22 d of the wiring 22. Further, the upper layer portion 21 u of the conductive film 21 m becomes the convex portion 21 d of the wiring 21. Further, the insulating films 35 a and 35 b and the insulating material deposited thereafter become a part of the inter-wiring insulating film 35. In the Z direction, the range in which the wiring 21 is arranged becomes the wiring layer 11, the range in which the wiring 22 is arranged becomes the wiring layer 13, and the range between the wiring layer 11 and the wiring layer 13, that is, the gap 30 and The range where the organic molecular layer 32 is formed is the memory layer 12.

  In addition, a memory cell including one organic molecular layer 32 is formed for each closest portion of the wiring 21 and the wiring 22. Thereby, the memory cells are arranged in a matrix along the X direction and the Y direction. Then, by applying a predetermined voltage between one wiring 21 and one wiring 22, the electronic state of the resistance change type molecular chain 31 included in the organic molecular layer 32 between them changes, and the electric resistance The value changes. Thereby, information can be written in each memory cell. Further, the written information can be read by detecting the electrical resistance value between the wiring 21 and the wiring 22.

Next, the effect of this embodiment is demonstrated.
As shown in FIG. 2, in the molecular memory 1 according to the present embodiment, the region 21 b facing the central portion in the width direction (Y direction) of the wiring 22 on the upper surface 21 a of the wiring 21 has both ends in the width direction of the wiring 22. It is located closer to the wiring 22 than the region 22c facing the part. Thereby, the distance between the both ends of the wiring 22 in the width direction and the wiring 21 is larger than the central portion in the width direction. For this reason, among the resistance change type molecular chains 31 bonded to the lower surface 22 a of the wiring 22, only the resistance change type molecular chain 31 bonded to the central portion in the width direction of the wiring 22 effectively functions as a memory element. The resistance variable molecular chain 31 bonded to both ends in the direction does not function as a memory element. That is, since both ends of the wiring 22 in the width direction have a large distance from the wiring 21, the resistance change type molecular chains 31 coupled to both ends of the wiring 22 do not interact electrically with the wiring 21. Does not contribute to the operation of the memory cell. As a result, even if the shape of the end portion in the width direction of the wiring 22 varies due to, for example, process factors, the characteristics of the memory cell are less affected by the variation. For example, as shown in FIG. 2, even if a defect occurs in the edge portion E of the wiring 22 and the lower surface of the wiring 22 is inclined with respect to the XY plane, the defect of the edge portion E causes the memory cell. Switching characteristics are less likely to vary.

Next, a comparative example will be described.
FIG. 12 is a cross-sectional view illustrating a molecular memory according to this comparative example.
As shown in FIG. 12, in the molecular memory 101 according to this comparative example, the upper surface 121a of the wiring 121 is flat. For this reason, in the upper surface 121a, the distance between the wiring 22 is substantially equal in the region facing the central portion in the width direction of the wiring 22 and the region facing both ends in the width direction. Accordingly, for example, if the shape of the end portion in the width direction of the wiring 22 varies due to process factors, the operation of the resistance change type molecular chain 31 varies due to this variation, and the switching characteristics of the memory cells vary.

  For example, when a defect occurs in the edge portion E of the wiring 22 and the lower surface is inclined, a gap between the resistance variable molecular chain 31 bonded to this portion and the wiring 121 is expanded, and the operation of the resistance variable molecular chain 31 is increased. The characteristics are different from the operation characteristics of the other resistance variable molecular chains 31. Since the variation in the shape of the end portion in the width direction of the wiring 22 is different for each memory cell, the switching characteristics of the memory cell vary. In particular, when the memory cell is miniaturized, since the ratio of the end portion of the wiring 22 is increased, the variation in switching characteristics is also increased.

Next, a second embodiment will be described.
FIG. 13 is a perspective view illustrating a molecular memory according to this embodiment.
FIG. 14 is a cross-sectional view illustrating a molecular memory according to this embodiment.
In order to make the drawing easier to see, only the conductive portion is shown in FIG. 13, and the insulating portion is not shown.

  As shown in FIGS. 13 and 14, in the molecular memory 2 according to the present embodiment, a plurality of wiring layers 11, a storage layer 12, and a wiring layer 13 are provided. The wiring layers 11 and the wiring layers 13 are alternately stacked along the Z direction with the memory layer 12 interposed therebetween. That is, the wiring layer 11, the memory layer 12, the wiring layer 13, the memory layer 12, the wiring layer 11, the memory layer 12, the wiring layer 13,. And in the wiring 21, the convex part 21d is formed not only on the upper surface 21a but also on the lower surface 21e. Thereby, in the lower surface 21 e of the wiring 21, the region facing the central portion in the width direction (X direction) of the wiring 22 is positioned below the region facing both ends in the width direction of the wiring 22.

  The convex portion 21d of the lower surface 21e of the wiring 21 can be formed by a method similar to the method of forming the convex portion 22d on the lower surface 22a of the wiring 22 described above. However, when the wiring 21 is formed, the width of the conductive film 22m to be processed into a line shape is set in the steps corresponding to the steps shown in FIGS. In the step corresponding to the step shown in FIG. 2, the width is made narrower than the width of the conductive film 22n processed into a line shape. Thereby, the convex portion 21 d whose length in the X direction is narrower than the width of the wiring 22 can be formed.

  According to the present embodiment, the memory cells can be arranged in the Z direction by stacking a plurality of wiring layers 11, memory layers 12, and wiring layers 13. That is, the memory cells can be arranged in a three-dimensional matrix along the X direction, the Y direction, and the Z direction. As a result, it is possible to improve the degree of integration of the memory cells and increase the recording density of the molecular memory. The configuration, manufacturing method, and operational effects other than those described above in the present embodiment are the same as those in the first embodiment described above.

Next, a third embodiment will be described.
FIG. 15 is a cross-sectional view illustrating a molecular memory according to this embodiment.
FIG. 16 is a circuit diagram illustrating a molecular memory according to this embodiment.

  As shown in FIG. 15, in the molecular memory 3 according to the present embodiment, the element isolation insulator 62 is selectively formed in the upper layer portion of the silicon substrate 61, and the region partitioned by the element isolation insulator 62 is formed. The source region 63 and the drain region 64 are formed apart from each other. A gate insulating film 66 is provided on the silicon substrate 61 and immediately above the channel region 65 between the source region 63 and the drain region 64, and a gate electrode 67 is provided thereon. Side walls 68 are provided on the sides of the gate electrode 67. Thereby, a field effect transistor 69 is formed.

  An interlayer insulating film 50 is provided on the silicon substrate 61. In the interlayer insulating film 50, a contact 51, a contact 52, a contact 53, a word line 54, and a bit line 55 are provided. The contact 52 is made of molybdenum, and the contact 53 is made of tungsten. A gap 56 is formed between the contact 52 and the contact 53 in the element isolation insulating film 50.

  The contact 51 is connected between the source region 63 and the word line 64. The lower end of the contact 52 is connected to the drain region 64, and the upper end is exposed in the gap 56. A convex portion 52 d is formed at the center of the upper end surface of the contact 52. The contact 53 is disposed immediately above the contact 52, and is separated from the contact 52 via a gap 56. The lower end of the contact 53 is exposed in the gap 56, and the upper end is connected to the bit line 55. A resistance variable molecular chain 31 is disposed in the gap 56 and is coupled to the contact 53. An organic molecular layer 32 is formed by a plurality of resistance variable molecular chains 31.

  Accordingly, as shown in FIG. 16, in the molecular memory 3, between the word line 54 and the bit line 55, an organic molecular layer 32 functioning as a storage element and a field effect transistor 69 functioning as a selection element are provided. 1R1T type memory cells connected in series are formed. The effect of this embodiment is the same as that of the first embodiment described above.

Next, a fourth embodiment will be described.
FIG. 17 is a perspective view illustrating a molecular memory according to this embodiment.
In order to make the drawing easier to see, only the conductive portion is shown in FIG. 17 and the insulating portion is not shown.

As shown in FIG. 17, in the molecular memory 4 according to the present embodiment, no protrusion 22 d (see FIG. 1) is formed on the wiring 22. For this reason, the lower surface 22a of the wiring 22 is flat.
Configurations and operational effects other than those described above in the present embodiment are the same as those in the first embodiment.

Hereinafter, the modification of the material in each above-mentioned embodiment is demonstrated.
FIG. 18 is a diagram illustrating a general formula of a resistance variable molecular chain according to a modification.
FIGS. 19A to 19F are diagrams illustrating molecular units that can form molecules in which a π-conjugated system extends in a one-dimensional direction.

  In each of the above-described embodiments, an example in which the resistance-change molecular chain 31 is 4- [2-amino-5-nitro-4- (phenethylenyl) phenethylenyl] benzenthiol shown in FIG. 3 is shown, but the present invention is not limited thereto. The resistance variable molecular chain 31 may be any molecule having a function of changing resistance. For example, the resistance-change molecular chain 31 may be a derivative of 4- [2-amino-5-nitro-4- (phenylthynyl) benzynethiol as shown as a general formula in FIG.

In the general formula shown in FIG. 18, the combination of X and Y is fluorine (F), chlorine (Cl), bromine (Br), iodine (I), cyano group (CN), nitro group (NO ₂ ). , An amino group (NH ₂ ), a hydroxyl group (OH), a carbonyl group (CO), and a carboxy group (COOH). Rn (n = 1 to 8) is an arbitrary atom excluding an atom whose outermost electron is d electron or f electron, and a characteristic group such as hydrogen (H), fluorine (F), chlorine ( Cl), bromine (Br), iodine (I), and a methyl group (CH ₃ ).

  Further, the resistance variable molecular chain 31 may be a molecule in which a π-conjugated system extends in a one-dimensional direction other than the molecular structure represented by the general formula in FIG. For example, a paraphenylene derivative, an oligothiophene derivative, an oligopyrrole derivative, an oligofuran derivative, or a paraphenylene vinylene derivative can be used.

  The molecular unit that can form a molecule in which a π-conjugated system extends in a one-dimensional direction may be paraphenylene shown in FIG. 19A or thiophene shown in FIG. 19B. The pyrrole shown in (c), the furan shown in FIG. 19 (d), the vinylene shown in FIG. 19 (e), or the alkyne shown in FIG. 19 (f) may be used. May be. In addition, a hetero 6-membered ring compound such as pyridine may be used.

  However, when the length of the π-conjugated system is short, the electrons injected from the electrode escape without staying on the molecule, so that it is a molecule of a certain length in order to accumulate charges. Preferably, it is desirable to calculate 5 or more in units of —CH═CH— in the one-dimensional direction. In the case of a benzene ring (paraphenylene), this corresponds to 3 or more. Note that the diameter of the benzene ring is about twice the spread width of polaron, which is a π-conjugated carrier. On the other hand, when the length of the π-conjugated system is long, a voltage drop due to charge conduction in the molecule becomes a problem. For this reason, it is desirable that the length of the π-conjugated system is 20 or less calculated by the unit of —CH═CH— in the one-way direction. This corresponds to 10 or less in the case of a benzene ring.

  Further, in each of the above-described embodiments, the example in which the wiring 21 is formed of molybdenum and the wiring 22 is formed of tungsten is shown, but the present invention is not limited to this. A suitable conductive material for forming the wirings 21 and 22 differs depending on the molecular structure of one end of the resistance variable molecular chain 31.

  For example, as shown in FIG. 3, when one end portion of the resistance change type molecular chain 31 is a thiol group, the material of the wiring 22, that is, the material of the portion where the resistance change type molecular chain 31 is to be chemically bonded is as described above. In addition to tungsten (W), gold (Au), silver (Ag), copper (Cu), tungsten nitride (WN), tantalum nitride (TaN), or titanium nitride (TiN) is preferable. Tungsten (W), gold (Au), or silver (Ag), which is easy to form a chemical bond, is desirable. On the other hand, the material of the wiring 21, that is, the material of the portion where the resistance change type molecular chain 31 is not desired to be chemically bonded, is not only molybdenum (Mo) but also tantalum (Ta), molybdenum nitride (MoN), or silicon (Si ) Is desirable.

  For example, when one end portion of the resistance variable molecular chain 31 is an alcohol group or a carboxyl group, the material of the portion where the resistance variable molecular chain 31 is to be chemically bonded is tungsten (W) or tungsten nitride (WN). Tantalum (Ta), tantalum nitride (TaN), molybdenum (Mo), molybdenum nitride (MoN), or titanium nitride (TiN), among which tantalum (Ta) and tantalum nitride are particularly easy to form chemical bonds. (TaN), molybdenum nitride (MoN), or titanium nitride (TiN) is desirable. On the other hand, it is desirable that the material of the portion where the resistance variable molecular chain 31 is not desired to be chemically bonded is gold (Au), silver (Ag), copper (Cu), or silicon (Si).

  Further, for example, when one end portion of the resistance change type molecular chain 31 is a silanol group, the material of the portion where the resistance change type molecular chain 31 is to be chemically bonded is preferably silicon (Si) or a metal oxide. . On the other hand, the material of the portion where the resistance change type molecular chain 31 is not desired to be chemically bonded is gold (Au), silver (Ag), copper (Cu), tungsten (W), tungsten nitride (WN), tantalum (Ta), Tantalum nitride (TaN), molybdenum (Mo), molybdenum nitride (MoN), or titanium nitride (TiN) is desirable. Further, when the wiring material is a compound, the composition of the compound can be selected as appropriate. Further, for example, graphene or carbon nanotubes can be applied as the wiring material.

  According to the embodiment described above, it is possible to realize a highly reliable molecular memory and a manufacturing method thereof.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalents thereof.

1, 2, 3, 4: Molecular memory, 10: Interlayer insulating film, 11: Wiring layer, 12: Memory layer, 13: Wiring layer, 21: Wiring, 21a: Upper surface, 21b, 21c: Region, 21d: Projection 21e: lower surface, 21m: conductive film, 21p: planar portion, 21u: upper layer portion, 22: wiring, 22a: lower surface, 22b, 22c: region, 22d: convex portion, 22m, 22n: conductive film, 30: gap, 31: resistance variable molecular chain, 32: organic molecular layer, 35: inter-wiring insulating film, 35a, 35b: insulating film, 40: sacrificial film, 41, 42: laminate, 50: interlayer insulating film, 51, 52, 53: contact, 52d: convex portion, 54: word line, 55: bit line, 56: air gap, 61: silicon substrate, 62: element isolation insulator, 63: source region, 64: drain region, 65: channel region, 66: Gate insulating film, 67: Over gate electrode, 68: side wall, 69: field-effect transistor, 101: molecular memory, 121: wiring, 121a: upper surface, E: edge

Claims (5)

A first wiring made of molybdenum and extending in the first direction;
A second wiring made of tungsten and extending in a second direction intersecting the first direction;
A resistance variable molecular chain disposed between the first wiring and the second wiring and coupled to the second wiring;
With
Of the surface of the first wiring on the second wiring side, the region facing the central portion in the width direction of the second wiring is more than the region facing the end portion in the width direction of the second wiring. Molecular memory located on the side. A first wiring made of a first conductive material and extending in a first direction;
A second wiring made of a second conductive material different from the first conductive material and extending in a second direction intersecting the first direction;
A resistance variable molecular chain disposed between the first wiring and the second wiring;
With
Of the surface of the first wiring on the second wiring side, the region facing the central portion in the width direction of the second wiring is more than the region facing the end portion in the width direction of the second wiring. Molecular memory located on the side.   The molecular memory according to claim 2, wherein the resistance variable molecular chain is bonded to the second conductive material. The first conductive material includes molybdenum;
The molecular memory according to claim 2, wherein the second conductive material includes tungsten. Laminating a first conductive film made of a first conductive material, a sacrificial film, and a second conductive film made of a second conductive material different from the first conductive material in this order;
The upper layer portion of the first conductive film, the sacrificial film, and the second conductive film are selectively removed to form a plurality of first stacked bodies extending in the first direction, and the first conductive film A step of side-etching the upper layer portion to make the width of the upper layer portion smaller than the width of the second conductive film;
Embedding a first insulating film between the first stacked bodies;
A plurality of second stacked bodies extending in a second direction intersecting the first direction by selectively removing the first insulating film, the second conductive film, the sacrificial film, and the first conductive film. Forming a step;
Removing the sacrificial film to form voids;
Arranging a resistance variable molecular chain in the void;
Embedding a second insulating film between the second stacked bodies in which the resistance variable molecular chains are disposed;
Forming a third conductive film extending in the first direction so as to be commonly connected to the second conductive film arranged along the first direction;
A method for manufacturing a molecular memory comprising:

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