CN103390628B - Resistor-type memory of rear end structure being integrated in integrated circuit and preparation method thereof - Google Patents

Abstract

The invention provides a resistive memory integrated in the back-end structure of an integrated circuit and a preparation method thereof, belonging to the technical field of memory. The resistive memory is integrated in the back-end structure. For the via holes used to form vertical electrodes, the dielectric layer around the via holes is partially etched horizontally and laterally to form one or more horizontal trenches. The horizontal trenches are used to The storage function layer is defined, and the metal inner electrode, the semiconductor layer, and the metal horizontal electrode for forming a bidirectional diode are sequentially formed in the horizontal trench. The resistive memory realizes three-dimensional stacking arrangement, high density, high preparation efficiency, low cost and low power consumption, and can be applied to bipolar resistive memory.

Description

Resistive memory integrated in the back-end structure of integrated circuit and its preparation method

technical field

The invention belongs to the field of memory technology, and relates to a resistive memory (Resistive Memory) with a 3D structure, in particular to a resistive memory with a 3D structure that can be integrated into the back-end structure of an integrated circuit and a preparation method thereof.

Background technique

The memory market driven by consumer electronics requires higher density, high speed, low power consumption, non-volatile and inexpensive memory products. So far, Flash is the most successful high-density non-volatile memory. However, as the size of devices continues to scale down, the development of Flash is limited. As one of the new non-volatile memories, resistive random access memory (RRAM), because of its simple structure, fast working speed, low power consumption and information Notable for its stability and non-volatility.

In particular, in order to further increase the integration density, three-dimensional (3D) integration technology has been put on the agenda. At present, a three-dimensional cross-stacked structure based on resistive memory has been reported. However, this structure has obvious defects of large leakage current, so it is proposed to introduce diode to reduce leakage current.

FIG. 1 is a schematic structural diagram of a non-volatile memory with a 3D structure in the prior art. The non-volatile memory may be a resistive memory, which is disclosed in US Patent Publication No. US2009/0261314A1, the assignee of which is Samsung Electronics Corporation. As shown in FIG. 1, the memory of the 3D structure includes a first electrode 110, a second electrode 140 intersecting the first electrode, a storage function layer 130 at the intersection of the first electrode 110 and the second electrode 140, and The semiconductor layer 120 forms a diode junction with the first electrode 110, and the diode D formed by the diode junction can be used as a gate transistor of each memory cell.

However, the diode D in the memory structure shown in Figure 1 only has unidirectional conduction characteristics. The variable storage function layer is programmed into high and low resistance states (corresponding to states "0" and "1" respectively). However, for the bipolar resistive memory function layer, the programming operation of switching between the high-resistance state and the low-resistance state cannot be performed on the selected memory cell, so it is not suitable for bipolar resistive memory application. Moreover, the area of the diode D junction used in the memory shown in FIG. 1 is generally large, which is not conducive to further increasing the integration density; moreover, no suggestion is given for its high-density integration in the back-end structure.

In addition, in order to reduce the cost of resistive memory and make it suitable for embedded applications, Chinese patent application numbers CN200710045407.6, CN200710043460.2 and other patents propose to integrate resistive memory into the back end of integrated circuits Structured scheme. However, in the resistive memories disclosed in these patents, the storage functional layers are all formed on the upper surface of the trenches or through holes, so it is difficult to improve the integration density of the memory (for example, on a through hole, only corresponding One storage unit), and the storage unit integrated on each dielectric layer of the back-end structure needs to be formed by the preparation process of the corresponding storage functional layer once, and the storage unit integrated on the multi-layer dielectric layer needs to be prepared for multiple storage functional layers It is formed by a technological process, and the preparation process is relatively complicated.

Contents of the invention

One of the objects of the present invention is to increase the integration density of the resistive memory with 3D structure.

Another object of the present invention is to make the resistive memory with 3D structure suitable for both unipolar resistive memory and bipolar resistive memory.

Another object of the present invention is to reduce the manufacturing cost of the resistive memory with 3D structure.

To achieve the above objects or other objects, the present invention provides the following technical solutions.

According to one aspect of the present invention, a resistive memory is provided, the resistive memory is integrated in the back-end structure of an integrated circuit, and the resistive memory includes:

vertical electrodes formed in the vias of the backend structure;

a diffusion barrier layer located between the vertical electrode and a dielectric layer for forming the through hole, the dielectric layer is partially horizontally etched to form a horizontal trench partially exposing the diffusion barrier layer;

a storage functional layer formed by oxidizing the exposed diffusion barrier layer; and

a metal internal electrode, a semiconductor layer, and a metal horizontal electrode sequentially formed in the horizontal trench;

Wherein, the metal inner electrode, the semiconductor layer and the metal horizontal electrode are used to form a bidirectional diode based on a metal-semiconductor-metal structure.

In the resistive memory according to an embodiment of the present invention, the thickness of the semiconductor layer is set such that the semiconductor layer is fully depleted when used to form a bidirectional diode.

Preferably, the thickness of the semiconductor layer is greater than or equal to 1 nanometer and less than or equal to 10 nanometers.

Preferably, the semiconductor layer is doped, and by controlling the doping concentration of the semiconductor layer, the turn-on voltage of the bidirectional semiconductor diode is lower than the reset voltage and set voltage of the memory.

Preferably, the semiconductor layer is an N-type doped silicon thin film layer.

In the resistive memory according to yet another embodiment of the present invention, the material of the metal internal electrode is the same as that of the metal horizontal electrode.

According to another embodiment of the present invention, the resistive memory, wherein the dielectric layer includes multiple first dielectric layers and multiple second dielectric layers, the first dielectric layers and the second dielectric layers are stacked alternately in sequence, the The second dielectric layer is etched horizontally and laterally to form horizontal trenches between the first dielectric layers.

Preferably, the diffusion barrier layer may be Ta, TaN, Ti, TiN, copper-manganese alloy or copper-ruthenium alloy, or a composite layer formed by a combination of the above materials.

Preferably, the storage functional layer may be tantalum oxide, titanium oxide, manganese oxide, ruthenium oxide, tantalum silicon oxide, manganese silicon oxide or ruthenium silicon oxide.

Preferably, the backend structure is a copper interconnection backend structure.

According to another aspect of the present invention, there is provided a method for preparing a resistive memory integrated in the back-end structure of an integrated circuit, which includes the following steps:

providing a backend structure in which vias have been formed in the dielectric layer;

depositing a diffusion barrier layer in the through hole;

filling the through holes to form vertical electrodes;

patterning at least one auxiliary vertical trench substantially parallel to the through hole in the dielectric layer;

forming at least one horizontal trench partially exposing the diffusion barrier layer by horizontal lateral pattern etching on sidewalls of the auxiliary vertical trench;

oxidizing the exposed diffusion barrier layer to form a storage function layer;

sequentially depositing and forming a metal internal electrode, a semiconductor layer, and a metal horizontal electrode in the horizontal trench; and

Patterning vertically partially etches the metal internal electrodes, the semiconductor layer and the metal horizontal electrodes to form isolation trenches, so as to electrically isolate memory cells correspondingly formed in different horizontal trenches.

The preparation method according to an embodiment of the present invention, wherein the dielectric layer has multiple first dielectric layers and multiple second dielectric layers, and the first dielectric layers and the second dielectric layers are stacked alternately in sequence;

In the step of forming the horizontal groove by etching, the second dielectric layer is etched horizontally and laterally to form a horizontal groove between the first dielectric layers.

Preferably, in the step of etching to form the horizontal trench, wet etching is used.

Preferably, the oxidation may be thermal oxidation, silicidation oxidation, nitriding oxidation, plasma oxidation or wet oxidation process.

Preferably, in the step of depositing and forming the metal internal electrodes, the metal internal electrodes are deposited and formed by chemical vapor deposition, plasma enhanced chemical vapor deposition or atomic layer deposition.

Preferably, in the step of depositing and forming the semiconductor layer, the semiconductor layer is deposited and formed by chemical vapor deposition or plasma enhanced chemical vapor deposition.

Preferably, in the step of depositing and forming the metal horizontal electrode, the metal horizontal electrode is deposited and formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition or electroplating.

According to another aspect of the present invention, a resistive memory is provided, the resistive memory is integrated in the back-end structure of an integrated circuit, and the resistive memory includes:

vertical electrodes formed in the vias of the backend structure;

a storage function layer located between the vertical electrode and a dielectric layer for forming the via hole, the dielectric layer is partially horizontally etched to form a horizontal trench partially exposing the storage function layer; and

a metal internal electrode, a semiconductor layer, and a metal horizontal electrode sequentially formed in the horizontal trench;

Wherein, the metal inner electrode, the semiconductor layer and the metal horizontal electrode are used to form a bidirectional diode based on a metal-semiconductor-metal structure.

In the resistive memory according to an embodiment of the present invention, the thickness of the semiconductor layer is set such that the semiconductor layer is fully depleted when used to form a bidirectional diode.

Preferably, the thickness of the semiconductor layer is greater than or equal to 1 nanometer and less than or equal to 10 nanometers.

Preferably, the semiconductor layer is doped, and by controlling the doping concentration of the semiconductor layer, the turn-on voltage of the bidirectional semiconductor diode is lower than the reset voltage and set voltage of the memory.

Preferably, the semiconductor layer is an N-type doped silicon thin film layer.

In the resistive memory according to yet another embodiment of the present invention, the material of the metal internal electrode is the same as that of the metal horizontal electrode.

According to another embodiment of the present invention, the resistive memory, wherein the dielectric layer includes multiple first dielectric layers and multiple second dielectric layers, the first dielectric layers and the second dielectric layers are stacked alternately in sequence, the The second dielectric layer is etched horizontally and laterally to form horizontal trenches between the first dielectric layers.

Preferably, the storage functional layer is copper oxide, tungsten oxide, tantalum oxide, titanium oxide, manganese oxide, ruthenium oxide, tantalum silicon oxide, manganese silicon oxide or ruthenium silicon oxide.

Preferably, the backend structure is a copper interconnection backend structure.

According to another aspect of the present invention, a method for preparing a resistive memory integrated in the back-end structure of an integrated circuit is provided, which includes the following steps:

providing a backend structure in which vias have been formed in the dielectric layer;

forming a storage function layer in the through hole;

filling the through holes to form vertical electrodes;

patterning at least one auxiliary vertical trench substantially parallel to the through hole in the dielectric layer;

forming at least one horizontal trench partially exposing the storage function layer by horizontal lateral pattern etching on the sidewall of the auxiliary vertical trench;

sequentially depositing and forming a metal internal electrode, a semiconductor layer, and a metal horizontal electrode in the horizontal trench; and

Patterning vertically partially etches the metal internal electrodes, the semiconductor layer and the metal horizontal electrodes to form isolation trenches, so as to electrically isolate memory cells correspondingly formed in different horizontal trenches.

The preparation method according to an embodiment of the present invention, wherein the dielectric layer has multiple first dielectric layers and multiple second dielectric layers, and the first dielectric layers and the second dielectric layers are stacked alternately in sequence;

In the step of forming the horizontal groove by etching, the second dielectric layer is etched horizontally and laterally to form a horizontal groove between the first dielectric layers.

Preferably, in the step of etching to form the horizontal trench, wet etching is used.

Preferably, in the step of depositing and forming the metal internal electrodes, the metal internal electrodes are deposited and formed by chemical vapor deposition, plasma enhanced chemical vapor deposition or atomic layer deposition.

Preferably, in the step of depositing and forming the semiconductor layer, the semiconductor layer is deposited and formed by chemical vapor deposition or plasma enhanced chemical vapor deposition.

Preferably, in the step of depositing and forming the metal horizontal electrode, the metal horizontal electrode is deposited and formed by chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition or electroplating.

According to still another aspect of the present invention, a resistive memory is provided, the resistive memory is integrated in the back-end structure of an integrated circuit, and the resistive memory includes:

metal vertical electrodes formed in the vias of the backend structure;

a semiconductor layer between the vertical electrode and a dielectric layer for forming the via hole, the dielectric layer is partially horizontally etched to form a horizontal trench partially exposing the semiconductor layer; and

A metal internal electrode, a storage function layer, and a horizontal electrode sequentially formed in the horizontal trench;

Wherein, the metal inner electrode, the semiconductor layer and the metal vertical electrode are used to form a bidirectional diode based on a metal-semiconductor-metal structure.

According to still another aspect of the present invention, there is provided a method for preparing a resistive memory integrated in the back-end structure of an integrated circuit, which includes the following steps:

providing a backend structure in which vias have been formed in the dielectric layer;

depositing and forming a semiconductor layer in the through hole;

filling the through holes to form metal vertical electrodes;

patterning at least one auxiliary vertical trench substantially parallel to the through hole in the dielectric layer;

forming at least one horizontal trench partially exposing the semiconductor layer by horizontal lateral patterning etching on sidewalls of the auxiliary vertical trench;

sequentially depositing and forming a metal internal electrode, a storage function layer, and a horizontal electrode in the horizontal trench; and

Patterning vertically partially etches the metal internal electrodes, storage function layers and horizontal electrodes to form isolation trenches, so as to electrically isolate memory cells correspondingly formed in different horizontal trenches.

The technical effects of the present invention are: (1) integrating the resistive memory into the back-end structure, truly realizing the three-dimensional stacking arrangement, which greatly improves the integration density of the resistive memory; (2) the three-dimensional stacking arrangement of memory cell arrays It can be completed through the one-time process described above, the preparation process is simple, and the preparation cost is low; (3) A bidirectional diode with gating function is embedded in each memory cell, and it can be driven by a large current when used as a gating tube Therefore, the storage density can be effectively improved; (4) the bidirectional diode can make the resistive memory of the 3D structure suitable for bipolar resistive memory; (5) the embedded bidirectional diode can effectively reduce the leakage current of the resistive memory , to reduce the power consumption of the resistive memory.

Description of drawings

The above and other objects and advantages of the present invention will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein the same or similar elements are denoted by the same reference numerals.

FIG. 1 is a schematic structural diagram of a non-volatile memory with a 3D structure in the prior art;

Fig. 2 to Fig. 9 schematically illustrate the structural changes in the process of preparing the resistive memory of the embodiment shown in Fig. 10;

FIG. 10 is a schematic structural diagram of a resistive memory integrated in the back-end structure of an integrated circuit according to an embodiment of the present invention;

11 to 17 are schematic diagrams showing structural changes in the process of preparing the resistive memory of the embodiment shown in FIG. 18;

Fig. 18 is a schematic structural diagram of a resistive memory integrated in the back-end structure of an integrated circuit according to another embodiment of the present invention;

FIG. 19 is a schematic structural diagram of a resistive memory integrated in the back-end structure of an integrated circuit according to yet another embodiment of the present invention.

detailed description

Presented below are some of the many possible embodiments of the invention, intended to provide a basic understanding of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of protection.

In the drawings, the thicknesses of layers and regions are exaggerated for clarity, but as schematic diagrams, they should not be regarded as strictly reflecting the proportional relationship of geometric dimensions. Moreover, the structural diagram in the accompanying drawings is a schematic diagram of a relatively idealized embodiment of the present invention. The curves obtained by thin film deposition and dry etching usually have the characteristics of bending or roundness, but in the illustrations of the embodiments of the present invention, they are all represented by rectangles. express. Therefore, the representation of the shape of the area in the figure is schematic, but this should not be considered as limiting the scope of the present invention. shape.

In this paper, the "metal" electrode is not limited to the electrode formed by a single metal layer or a single metal material, and its "metal" mainly refers to its metal characteristics, and it does not limit its structure or the type of metal material. The electrode formed by a single metal layer or a composite metal layer can also be a composite electrode formed by combining multiple metal materials, or an electrode formed by doping metals containing various elements.

In the drawings, the direction perpendicular to the surface of the semiconductor substrate is defined as the y-axis direction, that is, the direction parallel to the depth direction of the through hole or trench in the back-end structure, and the direction parallel to the surface of the semiconductor substrate is defined as the x-axis Orientation, however, is not limiting and is only used for relative description and clarification.

FIG. 10 is a schematic structural diagram of a resistive memory integrated in the back-end structure of an integrated circuit according to an embodiment of the present invention. 2 to 9 are schematic diagrams showing structural changes during the process of preparing the resistive memory of the embodiment shown in FIG. 10 . In the embodiments shown in Figures 2 to 10, the resistance type memory is integrated in the copper interconnection back-end structure as an example for illustration, but this is not limiting, and it can also be integrated in other types of back-end structures To form resistive memory in other embodiments of the present invention. The manufacturing method of the resistive memory of the present invention will be described in detail below with reference to FIGS. 2-10 , and the structure of the resistive memory shown in FIG. 10 will be further described.

First, a dielectric layer for forming via holes is formed. In the embodiment shown in Figure 2, after the front-end process of the integrated circuit and the tungsten plug leading out of the MOS tube 100 are completed, dielectric layers 201a, 202a, 201b, 202b and 201c are sequentially deposited thereon, wherein the dielectric layers 201a, 201b, 201c and the dielectric layers 202a and 202b are two different types of dielectric materials, which have different etching selectivity ratios for these two dielectric materials under certain etching conditions, so that it is convenient to etch them in subsequent steps. A dielectric material. Specifically, the dielectric layers 201a, 201b, and 201c can be SiO ₂ , the dielectric layers 202b, 202a are Si ₃ N ₄ , and the dielectric layers formed by the two dielectric materials are alternately stacked, and the specific number of layers depends on the density of the resistive memory to be formed. It is set that the more layers there are, the more resistive memory cells are stacked corresponding to one via hole or trench. Therefore, the material of the dielectric layer, the number of layers of the composite layer, etc. are not limited by the embodiments of the present invention.

Further, one or more through holes are formed by etching in the dielectric layer, and a diffusion barrier layer is formed in the through holes, and the through holes are filled to form vertical electrodes. This step can be accomplished using a process for forming a via structure or a trench structure that is commonly used in copper interconnection backend structures. As shown in FIG. 3 , the diffusion barrier layer 231 is formed in the through hole, and the vertical electrode 220 is also formed in the through hole, thereby forming the vertical electrode of the resistive memory. Diffusion barrier layer 231 is selected from a material that can have resistive storage characteristics after an oxidation process, for example, it can be Ta, TaN, Ti, TiN, copper-manganese alloy or copper-ruthenium alloy, or a composite layer formed by a combination of the above materials; diffusion barrier layer 231 It can be formed by physical vapor deposition (PVD), chemical vapor deposition (CVD) or atomic layer deposition (ALD). The vertical electrode 220 can be a metal conductive material, and can be a metal material such as Ta, TaN, Ti, TiN, Ru, W, Ir, Al, Cu, Ni or Co, or a composite layer formed by a combination of the above metal materials; it can generally be It is formed by physical vapor deposition (PVD), chemical vapor deposition (CVD) or electroplating.

Further, as shown in FIG. 4 , the dielectric layers 201c, 202b, 201b, 202a, and 201a are patterned and etched to form one or more auxiliary etching trenches 241 therein. Auxiliary etch trenches 241 are parallel to the vias, which are generally located next to corresponding vertical trenches or vias. Specifically, it can be formed by dry etching, and the commonly used dry etching gas can be CF ₄ or CHF ₃ . The sidewall of the auxiliary etching trench 241 exposes at least one or more dielectric layers 202 covered by the dielectric layer 201 , and in the illustrated example, the sidewall of the auxiliary etching trench 241 exposes part of the dielectric layer 202b, 202a. The width direction of the auxiliary etching trench 241 is the x direction, and its length direction is the direction perpendicular to the x direction and the y direction as shown in the figure, and its length direction basically defines the length direction of the horizontal electrode formed thereafter.

Further, as shown in FIG. 5 , at least one horizontal trench 242 partially exposing the diffusion barrier layer 231 is formed by horizontal lateral pattern etching on the sidewall of the auxiliary vertical trench 241 . In this embodiment, wet process is preferably used, for example, hot phosphoric acid solution is used to etch the exposed dielectric layers 202b, 202a until the diffusion barrier layer 231 is exposed. In this step, a plurality of horizontal grooves 242 can be formed simultaneously, and the number of horizontal grooves 242 can be changed according to the design of the number of dielectric layers. In the embodiment shown in FIG. 5, a through hole can be Correspondingly, four horizontal grooves 242 are formed.

Further, as shown in FIG. 6 , the exposed portion of the diffusion barrier layer 231 is oxidized to form a storage function layer 230 . Specifically, the oxidation process can be thermal oxidation, silicidation oxidation (doping the storage functional layer generated by oxidation with silicon), nitriding oxidation (doping the storage functional layer generated by oxidation with nitrogen), plasma oxidation or wet oxidation, etc. Functional layer 230 has resistive switching characteristics, and it can perform Set and Reset operations under the bias of an electrical signal; the material type of storage function layer 230 changes with the material type of diffusion barrier layer 231, which can be tantalum oxide, Titanium oxide, manganese oxide, ruthenium oxide, tantalum silicon oxide, manganese silicon oxide or ruthenium silicon oxide, etc.; the thickness of the storage function layer 230 may range from 2nm to 20nm (for example, 8nm).

Further, as shown in FIG. 7 , the metal internal electrode 240 is formed by depositing in the horizontal trench 242. Specifically, the metal internal electrode 240 can be deposited and formed by methods such as chemical vapor deposition (CVD), atomic layer deposition, or electroplating. The metal internal electrode 240 partially fills the horizontal groove 242 and is in direct contact with the storage function layer 230. At this time, the metal internal electrode 240 can form a good contact with the storage function layer 230; the material of the metal internal electrode 240 can be Ta, TaN, Ti, TiN , Ru, W, or Ir, with a thickness ranging from 10 nm to 50 nm (eg, 30 nm).

Further, as shown in FIG. 8 , a semiconductor layer 250 is deposited in the horizontal trench 242 , the semiconductor layer 250 covers the metal internal electrode 240 , and the contact between the two can form a Schottky junction. Specifically, the semiconductor layer 250 is deposited on the surface of the metal internal electrode 240 by methods such as chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD); in this example, the semiconductor layer 250 is an n-type semiconductor, It can not only form a Schottky junction with the metal internal electrode 240, but also form a Schottky junction with the metal horizontal electrode 260 formed in direct contact with it, so that the metal internal electrode 240, the semiconductor layer 250, the metal horizontal Electrode 260 forms a bidirectional diode. Preferably, the semiconductor layer 250 can be realized by silicon doped with N, P, As or Sb. To ensure that the semiconductor layer 250 can be fully depleted, its thickness range is controlled between 1 nanometer and 10 nanometers (for example, 6 nm). Moreover, by controlling the doping concentration in the semiconductor layer 250, the turn-on voltage of the formed bidirectional diode can be regulated to ensure that the turn-on voltage is lower than the Set (reset) voltage and the Reset (set) voltage of the memory (at the time when the diode is gated). case, the Set/Reset operation can be successfully implemented).

Further, as shown in FIG. 9, a metal horizontal electrode 260 is deposited, and the metal horizontal electrode 260 can be deposited by methods such as chemical vapor deposition (CVD), atomic layer deposition or electroplating, which can fill the horizontal groove 242, and have Sometimes the auxiliary vertical trenches 241 may also be filled. The metal horizontal electrode 260 covers and contacts the semiconductor layer 250, and a Schottky may be formed therebetween. The material of the metal horizontal electrode 260 may specifically be a metal material such as Ta, TaN, Ti, TiN, Ru, W or Ir.

Further, as shown in FIG. 10 , the metal internal electrode 240, the semiconductor layer 250 and the metal horizontal electrode 260 are partially etched by patterning vertically to form an isolation trench 243. In this way, through the vertical isolation trench 243, it is possible to achieve The electrical isolation between the memory cells corresponding to the adjacent horizontal trenches in the direction, that is, the electrical isolation between the metal horizontal electrodes 260 in different horizontal trenches, and the electrical isolation between the semiconductor layers 250 in different horizontal trenches are realized. Isolation, electrical isolation between metal internal electrodes 240 in different horizontal trenches. By setting the width and depth of the isolation trench 243, the metal internal electrode 240, the semiconductor layer 250, and the metal horizontal electrode 260 are partially etched while the dielectric layer is etched, so that the corresponding thin film layers in different isolation trenches are cut off, realizing electrical isolation.

So far, the preparation of the resistive memory including multiple memory cells integrated in the back-end structure is basically completed.

Continuing to refer to FIG. 10 , it provides an enlarged structure diagram of one of the memory cells, and provides an equivalent circuit diagram of the memory cell. In this memory cell, a metal-semiconductor-metal structure is formed between the metal internal electrode 240, the semiconductor layer 250, and the metal horizontal electrode 260, which can form a bidirectional diode. The vertical electrode 220, the memory function layer 230, and the metal internal electrode 240 1. A storage unit is formed between the semiconductor layer 250 and the metal horizontal electrode 260, the bidirectional diode can be used to realize the gate function, and the storage function layer 230 is used to realize information storage. It should be understood that, through the above preparation process, a plurality of memory cells can be correspondingly formed on one through hole at the same time, and multiple memory cells can be formed correspondingly to each through hole in a plurality of through hole arrays arranged in rows and columns at the same time. Therefore, a three-dimensional stacking arrangement is truly realized, which greatly improves the integration density of resistive memory, that is, increases its storage density. In addition, the above three-dimensional stacked array of memory cells can be completed through the one-time process described above (it is not necessary to repeat the preparation process layer by layer to achieve three-dimensional stacking), and the manufacturing cost is low.

Moreover, due to the bidirectional voltage turn-on characteristic of the bidirectional diode, the miswrite operation of unselected cells can be avoided, the leakage current can be reduced, and it is suitable for bipolar resistive memory.

Continuing to refer to FIG. 10 , the metal inner electrode 240 and the metal horizontal electrode 260 can be made of the same metal material, so that the turn-on voltage of the bidirectional diode formed therein is basically the same in both directions, that is, has a symmetrical turn-on voltage. The isolation trench 243 may also be continuously filled with a dielectric layer, so as to prepare for other preparation processes of the copper interconnection back-end structure.

FIG. 18 is a schematic structural diagram of a resistive memory integrated in the back-end structure of an integrated circuit according to another embodiment of the present invention. 11 to 17 are schematic diagrams showing structural changes during the process of preparing the resistive memory of the embodiment shown in FIG. 18 . In the embodiments shown in FIG. 11 to FIG. 18 , the storage function layer is formed by direct deposition instead of self-aligned oxidation of the diffusion barrier layer (the embodiment shown in FIG. 10 ). The manufacturing method of the resistive memory of the present invention will be described in detail below with reference to FIGS. 11 to 18 , and the structure of the resistive memory shown in FIG. 18 will be further described.

First, a dielectric layer for forming via holes is formed. In the embodiment shown in Figure 11, after the front-end process of the integrated circuit and the tungsten plug leading out of the MOS tube 100 are completed, dielectric layers 201a, 202a, 201b, 202b and 201c are sequentially deposited thereon, wherein the dielectric layers 201a, 201b, 201c and the dielectric layer 202a, 202b are two different types of dielectric materials, which have different etching selectivity ratios for these two dielectric materials under certain etching conditions, which is convenient for subsequent steps (forming horizontal trench step) etching one of the dielectric materials. Specifically, the dielectric layers 201a, 201b, and 201c can be SiO ₂ , the dielectric layers 202b, 202a are Si ₃ N ₄ , and the dielectric layers formed by the two dielectric materials are alternately stacked, and the specific number of layers depends on the density of the resistive memory to be formed. It is set that the more layers there are, the more resistive memory cells are stacked corresponding to one via hole or trench. Therefore, the material of the dielectric layer, the number of layers of the composite layer, etc. are not limited by the embodiments of the present invention.

Further, as shown in FIG. 12 , one or more through holes are formed by etching in the dielectric layer, and a storage function layer 330 is deposited in the through holes, and the vertical electrodes 220 are formed by filling the through holes. The storage function layer 330 is located between the vertical electrode 220 and the dielectric layer used to form the through hole. Certainly, in other embodiments, other functional layers may be formed between the storage functional layer 330 and the vertical electrode 220 , for example, a diffusion barrier layer, and a thin dielectric layer (for realizing functions such as improving low-resistance state resistance).

Specifically, the storage function layer 330 can be formed by physical vapor deposition (PVD), chemical vapor deposition (CVD) or atomic layer deposition and other thin film deposition processes, or can be formed by first depositing a metal thin film layer and then by an oxidation process. For example, the oxidation process can be thermal oxidation, silicidation oxidation (doping the storage function layer generated by oxidation with silicon), nitriding oxidation (doping the storage function layer generated by oxidation with nitrogen), plasma oxidation or wet oxidation and other processes; the storage function The material of layer 330 can be copper oxide (eg CuxO, 1<x≤2), tungsten oxide, tantalum oxide, titanium oxide, manganese oxide, ruthenium oxide, tantalum silicon oxide, manganese silicon oxide or Ruthenium silicon oxide, etc.; the thickness of the storage function layer 330 may range from 2nm to 20nm. The storage function layer 330 has resistive switching characteristics, and can realize the conversion between the high resistance state and the low resistance state under the action of an external electrical signal; the specific material selection, preparation process, thickness, etc. of the storage function layer 330 are not affected by the present invention. Example limitations.

The vertical electrode 220 can be a metal conductive material, and can be a metal material such as Ta, TaN, Ti, TiN, Ru, W, Ir, Al, Cu, Ni or Co, or a composite layer formed by a combination of the above metal materials; it can generally be It is formed by physical vapor deposition (PVD), chemical vapor deposition (CVD) or electroplating.

Further, as shown in FIG. 13 , the dielectric layers 201c, 202b, 201b, 202a, and 201a are patterned and etched to form one or more auxiliary etching trenches 241 therein. Auxiliary etch trenches 241 are parallel to the vias, which are generally located next to corresponding vertical trenches or vias. Specifically, it can be formed by dry etching, and the commonly used dry etching gas can be CF ₄ or CHF ₃ . The sidewall of the auxiliary etching trench 241 exposes at least one or more dielectric layers 202 covered by the dielectric layer 201 , and in the illustrated example, the sidewall of the auxiliary etching trench 241 exposes part of the dielectric layer 202b, 202a. The width direction of the auxiliary etching trench 241 is the x direction, and its length direction is the direction perpendicular to the x direction and the y direction as shown in the figure, and its length direction basically defines the length direction of the horizontal electrode formed thereafter.

Further, as shown in FIG. 14 , at least one horizontal trench 242 partially storing the functional layer 330 is formed by horizontal pattern etching on the sidewall of the auxiliary vertical trench 241 . In this embodiment, wet process is preferably used, for example, hot phosphoric acid solution is used to etch the exposed dielectric layers 202b, 202a until the diffusion barrier layer 231 is exposed. In this step, a plurality of horizontal grooves 242 can be formed simultaneously, and the number of horizontal grooves 242 can be changed according to the layer number design of the dielectric layer. In the embodiment shown in FIG. 14, a through hole can be Correspondingly, four horizontal grooves 242 are formed.

Further, as shown in FIG. 15 , the internal metal electrode 240 is deposited and formed in the horizontal trench 242. Specifically, the internal metal electrode 240 can be deposited and formed by chemical vapor deposition (CVD), atomic layer deposition, or electroplating. The metal internal electrode 240 partially fills the horizontal groove 242 and is in direct contact with the storage function layer 330. At this time, the metal internal electrode 240 can form a good contact with the storage function layer 330; the material of the metal internal electrode 240 can be Ta, TaN, Ti, TiN , Ru, W, or Ir, with a thickness ranging from 10 nm to 50 nm (eg, 30 nm).

Further, as shown in FIG. 16 , a semiconductor layer 250 is deposited in the horizontal trench 242 , the semiconductor layer 250 covers the metal internal electrode 240 , and the contact between the two can form a Schottky junction. Specifically, the semiconductor layer 250 is deposited on the surface of the metal internal electrode 240 by methods such as chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD); in this example, the semiconductor layer 250 is an n-type semiconductor, It can not only form a Schottky junction with the metal internal electrode 240, but also form a Schottky junction with the metal horizontal electrode 260 formed in direct contact with it, so that the metal internal electrode 240, the semiconductor layer 250, the metal horizontal Electrode 260 forms a bidirectional diode. Preferably, the semiconductor layer 250 can be realized by silicon doped with N, P, As or Sb. To ensure that the semiconductor layer 250 can be fully depleted, its thickness range is controlled between 1 nanometer and 10 nanometers (for example, 6 nm). Moreover, by controlling the content of doping elements in the semiconductor layer 250 , the turn-on voltage of the bidirectional diode formed therein can be regulated.

Further, as shown in FIG. 17, a metal horizontal electrode 260 is deposited, and the metal horizontal electrode 260 can be formed by depositing methods such as chemical vapor deposition (CVD), atomic layer deposition or electroplating, which can fill the horizontal groove 242, and has Sometimes the auxiliary vertical trenches 241 may also be filled. The metal horizontal electrode 260 covers and contacts the semiconductor layer 250, and a Schottky may be formed therebetween. The material of the metal horizontal electrode 260 may specifically be a metal material such as Ta, TaN, Ti, TiN, Ru, W or Ir.

Further, as shown in FIG. 18 , the metal internal electrode 240, the semiconductor layer 250, and the metal horizontal electrode 260 are partially etched vertically by patterning to form an isolation trench 243. In this way, through the vertical isolation trench 243, the x direction and y The electrical isolation between the memory cells corresponding to the adjacent horizontal trenches in the direction, that is, the electrical isolation between the metal horizontal electrodes 260 in different horizontal trenches, and the electrical isolation between the semiconductor layers 250 in different horizontal trenches are realized. Isolation, electrical isolation between metal internal electrodes 240 in different horizontal trenches. By setting the width and depth of the isolation trench 243, the metal internal electrode 240, the semiconductor layer 250, and the metal horizontal electrode 260 are partially etched while the dielectric layer is etched, so that the corresponding thin film layers in different isolation trenches are cut off, realizing electrical isolation.

So far, the preparation of the resistive memory including multiple memory cells integrated in the back-end structure is basically completed.

Continuing to refer to FIG. 18, the basic structure of the resistive memory of this embodiment is similar to that of the resistive memory of the embodiment shown in FIG. It has substantially the same advantages as the resistive memory of the embodiment shown in FIG. 10 as described above.

FIG. 19 is a schematic structural diagram of a resistive memory integrated in the back-end structure of an integrated circuit according to yet another embodiment. Compared with the embodiment shown in FIG. 18 , the main difference is that the positions of the storage function layer and the semiconductor layer are changed. Therefore, in the embodiment shown in FIG. 19, the vertical electrode 220 is selected as a metal vertical electrode, and the vertical electrode 220, the semiconductor layer 450, and the metal internal electrode 240 form a bidirectional diode based on a metal-semiconductor-metal structure with similar principles and functions. The storage function layer 430 is formed between the metal inner electrode 240 and the metal horizontal electrode 260 .

For the preparation method process of the embodiment shown in Figure 19, compared with the preparation method process of the embodiment shown in Figure 18, the main difference is that the order of "depositing a semiconductor layer" and "depositing to form a storage function layer" is changed; therefore, in During the preparation method of the embodiment shown in Figure 19, the following steps are included:

Depositing and forming a semiconductor layer 450 in the via hole;

filling the via holes to form metal vertical electrodes 220;

patterning and forming at least one auxiliary vertical trench 241 substantially parallel to the through hole in the dielectric layer;

forming at least one horizontal trench 243 partially exposing the semiconductor layer 450 by horizontal lateral pattern etching on the sidewall of the auxiliary vertical trench 241;

In the horizontal trench 243, deposit and form the metal internal electrode 240, the memory function layer 430, and the horizontal electrode 460 in sequence;

Patterning vertically partially etches the metal internal electrode 240 , the memory function layer 430 and the horizontal electrode 460 to form an isolation trench 243 , so as to electrically isolate memory cells correspondingly formed in different horizontal trenches.

The above examples mainly illustrate various resistive memories of the present invention and their preparation methods. Although only some of the embodiments of the present invention have been described, those skilled in the art should appreciate that the present invention can be implemented in many other forms without departing from the spirit and scope thereof. The examples and embodiments shown are therefore to be regarded as illustrative and not restrictive, and the invention may cover various modifications without departing from the spirit and scope of the invention as defined in the appended claims with replace.

Claims (32)

1. A resistive memory, characterized in that, said resistive memory is integrated in the back-end structure of an integrated circuit, comprising: vertical electrodes formed in the vias of the backend structure; a diffusion barrier layer located between the vertical electrode and a dielectric layer for forming the through hole, the dielectric layer is partially horizontally etched to form a horizontal trench partially exposing the diffusion barrier layer; a storage functional layer formed by oxidizing the exposed diffusion barrier layer; and a metal internal electrode, a semiconductor layer, and a metal horizontal electrode sequentially formed in the horizontal trench; Wherein, the metal inner electrode, the semiconductor layer and the metal horizontal electrode are used to form a bidirectional diode based on a metal-semiconductor-metal structure; The semiconductor layer is doped, and by controlling the doping concentration of the semiconductor layer, the turn-on voltage of the bidirectional semiconductor diode is lower than the reset voltage and set voltage of the memory. 2. The resistive memory according to claim 1, wherein the thickness of the semiconductor layer is set such that the semiconductor layer is fully depleted when used to form a bidirectional diode. 3. The resistive memory according to claim 2, wherein the thickness of the semiconductor layer is greater than or equal to 1 nanometer and less than or equal to 10 nanometers. 4. The resistive memory according to claim 1 or 2, wherein the semiconductor layer is an N-type doped silicon thin film layer. 5. The resistive memory according to claim 1 or 2, wherein the material of the metal internal electrode is the same as that of the metal horizontal electrode. 6. The resistive memory according to claim 1, wherein the dielectric layer comprises multiple first dielectric layers and multiple second dielectric layers, and the first dielectric layers and the second dielectric layers are stacked alternately in sequence , the second dielectric layer is horizontally and laterally etched to form a horizontal trench between the first dielectric layers. 7. The resistive memory according to claim 1, wherein the diffusion barrier layer is Ta, TaN, Ti, TiN, copper-manganese alloy or copper-ruthenium alloy, or a composite layer formed by a combination of the above materials. 8. The resistive memory according to claim 1, wherein the memory functional layer is tantalum oxide, titanium oxide, manganese oxide, ruthenium oxide, tantalum silicon oxide, manganese silicon oxide or ruthenium silicon oxide. 9. The resistive memory according to claim 1, wherein the back-end structure is a copper interconnection back-end structure. 10. A preparation method of a resistive memory integrated in the back-end structure of an integrated circuit, characterized in that it comprises the following steps: providing a backend structure in which vias have been formed in the dielectric layer; depositing a diffusion barrier layer in the through hole; filling the through holes to form vertical electrodes; patterning at least one auxiliary vertical trench substantially parallel to the through hole in the dielectric layer; forming at least one horizontal trench partially exposing the diffusion barrier layer by horizontal lateral pattern etching on sidewalls of the auxiliary vertical trench; oxidizing the exposed diffusion barrier layer to form a storage function layer; sequentially depositing and forming a metal internal electrode, a semiconductor layer, and a metal horizontal electrode in the horizontal trench; and Patterning vertically partially etches the metal internal electrodes, the semiconductor layer and the metal horizontal electrodes to form isolation trenches, so as to electrically isolate memory cells correspondingly formed in different horizontal trenches. 11. The preparation method according to claim 10, wherein the dielectric layer has multiple first dielectric layers and multiple second dielectric layers, and the first dielectric layers and the second dielectric layers are stacked alternately in sequence; In the step of forming the horizontal groove by etching, the second dielectric layer is etched horizontally and laterally to form a horizontal groove between the first dielectric layers. 12 . The manufacturing method according to claim 10 , wherein, in the step of forming the horizontal groove by etching, wet etching is used. 13 . 13 . The preparation method according to claim 10 , wherein the oxidation is thermal oxidation, silicon oxidation, nitriding oxidation, plasma oxidation or wet oxidation process. 14 . 14. The preparation method according to claim 10, characterized in that, in the step of depositing and forming the metal inner electrode, chemical vapor deposition, plasma enhanced chemical vapor deposition or atomic layer deposition is used to deposit and form the metal inner electrode. electrode. 15. The preparation method according to claim 10, characterized in that, in the step of depositing and forming the semiconductor layer, the semiconductor layer is deposited and formed by chemical vapor deposition or plasma enhanced chemical vapor deposition. 16. The preparation method according to claim 10, characterized in that, in the step of depositing and forming the metal horizontal electrode, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition or electroplating are used to deposit and form the metal horizontal electrode. Metal horizontal electrodes. 17. A resistive memory, characterized in that the resistive memory is integrated in the back-end structure of an integrated circuit, comprising: vertical electrodes formed in the vias of the backend structure; a storage function layer located between the vertical electrode and a dielectric layer for forming the via hole, the dielectric layer is partially horizontally etched to form a horizontal trench partially exposing the storage function layer; and a metal internal electrode, a semiconductor layer, and a metal horizontal electrode sequentially formed in the horizontal trench; Wherein, the metal inner electrode, the semiconductor layer and the metal horizontal electrode are used to form a bidirectional diode based on a metal-semiconductor-metal structure; The semiconductor layer is doped, and by controlling the doping concentration of the semiconductor layer, the turn-on voltage of the bidirectional semiconductor diode is lower than the reset voltage and set voltage of the memory. 18. The resistive memory according to claim 17, wherein the thickness of the semiconductor layer is set such that the semiconductor layer is fully depleted when used to form a bidirectional diode. 19. The resistive memory according to claim 18, wherein the thickness of the semiconductor layer is greater than or equal to 1 nanometer and less than or equal to 10 nanometers. 20. The resistive memory according to claim 17 or 18, wherein the semiconductor layer is an N-type doped silicon thin film layer. 21. The resistive memory according to claim 17 or 18, wherein the material of the metal internal electrode is the same as that of the metal horizontal electrode. 22. The resistive memory according to claim 17, wherein the dielectric layer comprises multiple first dielectric layers and multiple second dielectric layers, and the first dielectric layers and the second dielectric layers are stacked alternately in sequence , the second dielectric layer is horizontally and laterally etched to form a horizontal trench between the first dielectric layers. 23. The resistive memory according to claim 17, wherein the storage functional layer is copper oxide, tungsten oxide, tantalum oxide, titanium oxide, manganese oxide, ruthenium oxide, tantalum silicon oxide compounds, manganese silicon oxide or ruthenium silicon oxide. 24. The resistive memory according to claim 17, wherein the back-end structure is a copper interconnection back-end structure. 25. A method for preparing a resistive memory integrated in the back-end structure of an integrated circuit, comprising the following steps: providing a backend structure in which vias have been formed in the dielectric layer; forming a storage function layer in the through hole; filling the through holes to form vertical electrodes; patterning at least one auxiliary vertical trench substantially parallel to the through hole in the dielectric layer; forming at least one horizontal trench partially exposing the storage function layer by horizontal lateral pattern etching on the sidewall of the auxiliary vertical trench; sequentially depositing and forming a metal internal electrode, a semiconductor layer, and a metal horizontal electrode in the horizontal trench; and Patterning vertically partially etches the metal internal electrodes, the semiconductor layer and the metal horizontal electrodes to form isolation trenches, so as to electrically isolate memory cells correspondingly formed in different horizontal trenches. 26. The preparation method according to claim 25, wherein the dielectric layer has multiple first dielectric layers and multiple second dielectric layers, and the first dielectric layers and the second dielectric layers are stacked alternately in sequence; In the step of forming the horizontal groove by etching, the second dielectric layer is etched horizontally and laterally to form a horizontal groove between the first dielectric layers. 27. The manufacturing method according to claim 26, characterized in that, in the step of forming the horizontal groove by etching, wet etching is used. 28. The preparation method according to claim 26, characterized in that, in the step of depositing and forming the metal inner electrode, chemical vapor deposition, plasma enhanced chemical vapor deposition or atomic layer deposition is used to deposit and form the metal inner electrode. electrode. 29. The preparation method according to claim 26, wherein in the step of depositing and forming the semiconductor layer, the semiconductor layer is deposited and formed by chemical vapor deposition or plasma enhanced chemical vapor deposition. 30. The preparation method according to claim 26, characterized in that, in the step of depositing and forming the metal horizontal electrode, chemical vapor deposition, plasma enhanced chemical vapor deposition, atomic layer deposition or electroplating are used to deposit and form the metal horizontal electrode. Metal horizontal electrodes. 31. A resistive memory, characterized in that the resistive memory is integrated in the back-end structure of an integrated circuit, comprising: metal vertical electrodes formed in the vias of the backend structure; a semiconductor layer between the vertical electrode and a dielectric layer for forming the via hole, the dielectric layer is partially horizontally etched to form a horizontal trench partially exposing the semiconductor layer; and A metal internal electrode, a storage function layer, and a horizontal electrode sequentially formed in the horizontal trench; Wherein, the metal internal electrode, the semiconductor layer and the metal vertical electrode are used to form a bidirectional diode based on a metal-semiconductor-metal structure; The semiconductor layer is silicon doped with N, P, As or Sb elements, and the turn-on voltage of the bidirectional diode is regulated by controlling the doping concentration of the semiconductor layer, so as to ensure that the turn-on voltage of the bidirectional diode is lower than the reset voltage of the memory voltage and set voltage. 32. A method for preparing a resistive memory integrated in the back-end structure of an integrated circuit, comprising the following steps: providing a backend structure in which vias have been formed in the dielectric layer; depositing and forming a semiconductor layer in the through hole; filling the through holes to form metal vertical electrodes; patterning at least one auxiliary vertical trench substantially parallel to the through hole in the dielectric layer; forming at least one horizontal trench partially exposing the semiconductor layer by horizontal lateral patterning etching on sidewalls of the auxiliary vertical trench; sequentially depositing and forming a metal internal electrode, a storage function layer, and a horizontal electrode in the horizontal trench; and Patterning vertically partially etches the metal internal electrodes, storage function layers and horizontal electrodes to form isolation trenches, so as to electrically isolate memory cells correspondingly formed in different horizontal trenches.