CN112909160B - Phase change memory cell with low operation power consumption and preparation method thereof - Google Patents

Abstract

The invention discloses a phase-change memory unit with low operation power consumption and a preparation method thereof, belonging to the technical field of micro-nano electronics. A phase-change memory cell with low operating power consumption includes a substrate and a bottom electrode, a first insulating layer, a phase-change material layer, a second insulating layer, and a top electrode sequentially arranged on the substrate, and the first insulating layer is provided with a phase change A material plug, a first stress material layer is arranged around the phase change material plug, the material of the first stress material layer is a thermal stress material, a top electrode plug is arranged in the second insulating layer, and the phase change material is The projections of the plug posts and the top electrode plug posts on the substrate do not coincide. A first stress material layer is arranged around the phase change material plug. When the phase change material plug is heated, the first stress material layer will provide the phase change material plug with compressive stress parallel to the direction of the substrate, thereby reducing the The activation energy of the phase change material plays a role in reducing the operating power consumption of the phase change memory cell.

Description

A phase-change memory cell with low operating power consumption and method of making the same

technical field

The invention relates to the technical field of micro-nano electronics, in particular to a phase-change memory unit with low operating power consumption and a preparation method thereof.

Background technique

With the exponential increase in the amount of data caused by the development of science and technology, massive data requires faster and larger capacity memory to process and store, and the development of higher density and higher speed memory is an urgent need for scientific and technological development; traditional Although the non-volatile solid-state storage can meet the basic requirements in terms of capacity through some improvements in process structure, its read and write speed is relatively slow, which makes it a gap between it and the memory with fast speed but small capacity. Larger gap, which needs to be filled by new types of storage with larger capacity and faster speed. The latest research shows that the three-dimensional stacked phase-change memory crossbar array is the most promising candidate. Compared with other new memory technologies, its excellent performance such as better CMOS process compatibility, durability, and stability makes it popular. focus on.

The storage principle of the phase change memory is to use the Joule heat generated by the electric pulse to make the phase change memory material unit switch between a crystalline state with a lower resistance state and an amorphous state with a higher resistance state. The energy consumption of these two processes is relatively high relative to other types of storage, so there is a large heat dissipation in traditional phase change memory. At present, the solutions for reducing the power consumption of phase-change memory devices mainly focus on phase-change materials, such as doping and modification of phase-change materials.

SUMMARY OF THE INVENTION

In order to reduce operating power consumption and heat dissipation, embodiments of the present invention provide a phase-change memory cell with low operating power consumption and a manufacturing method thereof. The technical solution is as follows:

In one aspect, an embodiment of the present invention provides a phase-change memory cell with low operating power consumption, the phase-change memory cell comprising:

a substrate and a bottom electrode, a first insulating layer, a phase change material layer, a second insulating layer and a top electrode sequentially arranged on the substrate,

The first insulating layer is provided with a phase change material plug, one end of the phase change material plug is connected to the phase change material layer, and the other end of the phase change material plug is connected to the bottom The electrodes are connected, a first stress material layer is arranged around the phase change material plug, the material of the first stress material layer is a thermal stress material, and the thermal expansion coefficient of the thermal stress material is larger than that of the phase change material the thermal expansion coefficient;

The second insulating layer is provided with a top electrode plug, one end of the top electrode plug is connected to the phase change material layer, and the other end of the top electrode plug is connected to the top electrode, The projections of the phase change material plugs and the top electrode plugs on the substrate do not coincide.

Optionally, a second stress material layer is provided around the top electrode plug, and the material of the second stress material layer is a thermal stress material.

Optionally, the projection of the phase change material plug on the substrate is within the projection of the second stress material layer on the substrate.

Optionally, the phase change memory unit further includes:

a lower stress material layer between the first insulating layer and the phase change material layer and an upper stress material layer between the second insulating layer and the phase change material layer, the upper stress material layer and the material of the lower stress material layer are all thermal stress materials.

Optionally, the thermal expansion coefficient of the thermal stress material is at least 1.5 times the thermal expansion coefficient of the phase change material.

Optionally, the thermal stress material is benzocyclobutene.

On the other hand, an embodiment of the present invention also provides a method for fabricating a phase-change memory cell with low operating power consumption, including:

forming a bottom electrode on the substrate;

A first insulating layer is prepared on the bottom electrode, and the first insulating layer is patterned to obtain a first through hole, and a phase change material plug and a first stress material layer are prepared in the first through hole , one end of the phase change material plug is connected to the bottom electrode, the first stress material layer is arranged around the phase change material plug, and the material of the first stress material layer is thermal stress material, the thermal expansion coefficient of the thermal stress material is greater than the thermal expansion coefficient of the phase change material;

preparing a phase change material layer on the first insulating layer, and the other end of the phase change material plug is connected to the phase change material layer;

A second insulating layer is prepared on the phase change material layer, and the second insulating layer is patterned to obtain a second through hole, and a top electrode plug is prepared in the second through hole, and the top electrode One end of the plug post is connected to the phase change material layer, and the projections of the phase change material plug post and the top electrode plug post on the substrate are not coincident;

A top electrode is prepared on the second insulating layer, and the other end of the top electrode plug is connected to the top electrode.

Optionally, the method further includes preparing a second stress material layer in the second through hole, the second stress material layer is disposed around the top electrode plug, the second stress material layer is The material of the layer is a thermally stressed material.

Optionally, the projection of the phase change material plug on the substrate is within the projection of the second stress material layer on the substrate.

Optionally, the thermal expansion coefficient of the stress material is at least 1.5 times the thermal expansion coefficient of the phase change material.

The beneficial effects brought by the technical solutions provided by the embodiments of the present invention include at least:

The phase change memory cell in the present application includes a substrate and a bottom electrode, a first insulating layer, a phase change material layer, a second insulating layer and a top electrode sequentially arranged on the substrate, and the phase change material is arranged in the first insulating layer a plug, one end of the phase change material plug is connected to the phase change material layer, the other end of the phase change material plug is connected to the bottom electrode, and a first stress material layer is arranged around the phase change material plug, The material of the first stress material layer is a thermal stress material, and the thermal expansion coefficient of the thermal stress material is greater than that of the phase change material. The second insulating layer is provided with a top electrode plug, one end of the top electrode plug is connected to the phase change material layer, the other end of the top electrode plug is connected to the top electrode, and the phase change material plug is connected to the top electrode. The projections of the plugs on the substrate do not coincide.

A first stress material layer is arranged around the phase change material plug. When the phase change material plug is heated, since the thermal expansion coefficient of the thermal stress material is greater than that of the phase change material, there is a difference in volume expansion between the two. Therefore, the first stress material layer will provide compressive stress parallel to the substrate direction for the phase change material plug, thereby reducing the activation energy of the phase change material and reducing the operating power consumption of the phase change memory cell.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

1 is a schematic structural diagram of a phase-change memory cell with low operating power consumption provided by an embodiment of the present invention;

2 is a schematic structural diagram of another phase-change memory cell with low operating power consumption provided by an embodiment of the present invention;

3 is a flowchart of a method for fabricating a phase-change memory cell with low operating power consumption provided by an embodiment of the present invention;

4 to 9 are process diagrams of a method for fabricating a phase-change memory cell with low operating power consumption according to an embodiment of the present invention;

FIG. 10 is a flowchart of another method for fabricating a phase-change memory cell with low operating power consumption according to an embodiment of the present invention.

Description of drawings:

Substrate 100, bottom electrode 200, first insulating layer 300, first stress material layer 301, phase change material plug 302, lower stress material layer 303, phase change material layer 400, second insulating layer 500, second stress Material layer 501, top electrode plug 502, upper stress material layer 503, top electrode 600

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Embodiments of the present invention provide a phase-change memory cell with low operating power consumption. FIG. 1 is a schematic structural diagram of a phase-change memory cell with low operating power consumption provided by an embodiment of the present invention. As shown in FIG. 1 , the phase-change memory cell includes a substrate 100 and a bottom electrode 200 arranged on the substrate 100 in sequence. , the first insulating layer 300, the phase change material layer 400, the second insulating layer 500 and the top electrode 600,

The first insulating layer 300 is provided with a phase change material plug 302, one end of the phase change material plug 302 is connected to the phase change material layer 400, and the other end of the phase change material plug 302 is connected to the bottom electrode 200, surrounding the A first stress material layer 301 is arranged around the phase change material plug 302, the first stress material layer 301 is a thermal stress material, and the thermal expansion coefficient of the thermal stress material is greater than that of the phase change material;

The second insulating layer 500 is provided with a top electrode plug 502 , one end of the top electrode plug 502 is connected to the phase change material layer 400 , and the phase change material plug 302 and the top electrode plug 502 are on the substrate 100 The projections do not overlap, and the other end of the top electrode plug 502 is connected to the top electrode 600 .

The projections of the phase change material plugs 302 and the top electrode plugs 502 on the substrate 100 do not overlap, so that there is a certain distance between the top electrode 600 and the bottom electrode 200 in the direction parallel to the substrate 100, which can increase the phase transition The current density within the structure reduces temperature dissipation and improves heat utilization efficiency, thereby reducing operating current.

The storage principle of the phase change memory is to use the Joule heat generated by the electric pulse to make the phase change memory material unit switch between a crystalline state with a lower resistance state and an amorphous state with a higher resistance state. The energy of switching between the crystalline state and the non-static state is called the activation energy of the phase change material. Applying physical stress to the phase change material can reduce the activation energy of the phase change material. A first stress material layer 301 is arranged around the phase change material plug 302. When the phase change material plug 302 is heated, since the thermal expansion coefficient of the thermal stress material is greater than that of the phase change material, there is a volume between the two. Therefore, the first stress material layer 301 will provide a compressive stress parallel to the direction of the substrate 100 for the phase change material plug 302, thereby reducing the activation energy of the phase change material and reducing the operating power consumption of the phase change memory cell. effect.

The first stress material layer 301 surrounds the phase change material plug 302. It can be understood that the surrounding refers to a closed surrounding along the circumferential direction, but does not limit the cross-sectional shape of the phase change material plug 302, which can be A circle can also be other closed shapes. Correspondingly, the cross-sectional shape of the first stress material layer 301 is a closed figure including the cross-section of the phase change material plug 302 , which is not limited to a circle, and may also be other closed figures.

Optionally, the minimum distance d between the cross-sectional edge of the first stress material layer 301 and the cross-sectional edge of the phase change material plug 302 is not less than 20 nm, so as to ensure the generation between the first stressed material layer 301 and the phase change material plug 302. Sufficient volume change to provide sufficient compressive stress.

Preferably, the minimum distance d between the cross-sectional edge of the first stress material layer 301 and the cross-sectional edge of the phase change material plug 302 is a fixed value to ensure the compressive stress provided by the first stress material layer 301 for the phase change material plug 302 is uniform, so that the activation energy change of the phase change material is uniform, thereby ensuring the stability of the power consumption of the phase change unit.

In some embodiments, a second stress material layer 501 is provided around the top electrode plug 502 , the material of the second stress material layer 501 is a thermal stress material, and the thermal expansion coefficient of the thermal stress material is greater than the phase transition The thermal expansion coefficient of the material. A second stress material layer 501 is arranged around the top electrode plug 502. When the top electrode plug 502 is heated, since the thermal expansion coefficient of the thermal stress material is greater than that of the phase change material, there is a difference in volume expansion between the two. , so that the second stress material layer 501 provides the phase change material layer 400 with a compressive stress perpendicular to the direction of the substrate 100 , thereby reducing the activation energy of the phase change material and reducing the operating power consumption of the phase change memory cell.

Optionally, the projection of the phase change material plug 302 on the substrate 100 is within the projection of the second stress material on the substrate 100 .

The second stress material layer 501 surrounds the top electrode plug 502, wherein the surrounding refers to a closed surrounding along the circumferential direction, but does not limit the cross-sectional shape of the top electrode plug 502, which may be a circle or a Other closed graphics. Correspondingly, the cross-sectional shape of the second stress material layer 501 is a closed figure including the phase change material plug 302 or the top electrode plug 502 , which is not limited to a circle, but can also be other closed figures.

The projection of the phase change material plug 302 on the substrate 100 is located within the projection of the second stress material layer 501 on the substrate 100. When the top electrode plug 502 is electrified and heated, the second stress material layer 501 is heated . Since the thermal expansion coefficient of the thermal stress material is greater than the thermal expansion coefficient of the phase change material, the expansion and deformation of the second stress material layer 501 will provide the phase change material plug 302 with a compressive stress in the direction perpendicular to the substrate 100, further reducing the phase change material plug The activation energy of the pillars 302, thereby reducing the operating power consumption of the phase change memory cell.

Optionally, the thermal expansion coefficient of the thermal stress material is at least 1.5 times the thermal expansion coefficient of the phase change material to ensure that sufficient compressive stress is generated between the thermal stress material and the phase change material to affect the activation energy of the phase change material. Specifically, the thermal stress material may be an insulating material with a large thermal expansion coefficient, such as benzocyclobutene. The phase change material may be one or a mixture of two or more phase change materials such as germanium tellurium, antimony tellurium and germanium antimony tellurium.

Optionally, FIG. 2 is a schematic structural diagram of another phase-change memory cell with low operating power consumption provided by an embodiment of the present invention. Compared with the phase change memory cell shown in FIG. 1 , the phase change memory cell shown in FIG. 2 further includes: a lower stress material layer 303 located between the first insulating layer 300 and the phase change material layer 400 and a second insulating layer 303 . The materials of the upper stress material layer 503 between the layer 500 and the phase change material layer 400 , the upper stress material layer 503 and the lower stress material layer 303 are all thermal stress materials.

Since both the lower stress material layer 303 and the upper stress material layer 503 are in contact with the phase change material layer 400 , the action range of the compressive stress is expanded, so that the activation energy of the phase change material can be further reduced.

Optionally, the thicknesses of both the lower stress material layer 303 and the upper stress material layer 503 are not more than 20 nm, so as to reduce the influence of deformation on the integrity of the phase change material unit.

FIG. 3 is a flowchart of a method for fabricating a phase-change memory cell with low operating power consumption according to an embodiment of the present invention, which is used to fabricate the phase-change memory cell shown in FIG. 1 . As shown in Figure 3, the method includes:

Step S11: forming a bottom electrode on the substrate.

Optionally, the substrate 100 may be ITO conductive glass or any substrate 100 whose surface is covered with conductive thin films such as Ni/Au, Ti/Au, Ag, Ti/Pt, etc.

Optionally, the material of the bottom electrode 200 may be metal materials such as tungsten, titanium-tungsten, titanium-platinum, nickel-gold, and the like, and the thickness of the bottom electrode 200 is between 10 nm and 200 nm.

Specifically, as shown in Fig. 4, taking the silicon wafer as an example, the silicon wafer is placed in acetone and alcohol for ultrasonic cleaning for about ten minutes; after the ultrasonication is completed, the residual liquid on the surface is blown and dried by a nitrogen gun for use. .

A metal conductive layer such as titanium platinum, nickel gold, etc. can be evaporated on the clean silicon wafer by magnetron sputtering or electron beam evaporation, and its thickness is between 10nm-200nm.

Step S12 : preparing a first insulating layer on the bottom electrode, patterning the first insulating layer to obtain a first through hole, and preparing a phase change material plug and a first through hole in the first through hole A stress material layer, one end of the phase change material plug is connected to the bottom electrode, the first stress material layer is arranged around the phase change material plug, the material of the first stress material layer is Being a thermal stress material, the thermal expansion coefficient of the thermal stress material is greater than the thermal expansion coefficient of the phase change material.

Optionally, the thermal expansion coefficient of the thermal stress material is at least 1.5 times the thermal expansion coefficient of the phase change material, so that sufficient compressive stress is generated between the thermal stress material and the phase change material, thereby affecting the activation energy of the phase change material. Specifically, the thermal stress material may be an insulating material with a large thermal expansion coefficient, such as benzocyclobutene. The phase change material may be one or a mixture of two or more phase change materials such as germanium tellurium, antimony tellurium and germanium antimony tellurium.

In some embodiments, step S12 may include:

Step S121, preparing a first insulating layer on the bottom electrode.

Specifically, using PECVD (Plasma Enhanced Chemical Vapour Deposition, plasma enhanced chemical vapor deposition), magnetron sputtering or ALD (Atomic Layer Deposition, atomic layer deposition) to grow a dense layer of silicon dioxide or oxide on the bottom electrode 200 Other insulating materials such as aluminum are used as the first insulating layer 300 , and the thickness can be above the micrometer level according to design requirements.

Step S122, patterning the first insulating layer to obtain a first through hole.

Specifically, as shown in FIG. 5 , the pattern is transferred onto the first insulating layer 300 in combination with photolithography or other mask processes. Using the etching method, the first through hole is etched, and the depth of the etching here should be skipped to ensure that the bottom electrode 200 can be exposed.

In step S123, a first stress material layer is prepared in the first through hole.

Specifically, use magnetron sputtering and other methods to fill the first through hole with an insulating material with a larger thermal expansion coefficient as a stress material, the filling height is not lower than the depth of the first through hole, and then use CMP (Chemical-Mechanical Polishing) after the peeling is completed. , chemical mechanical polishing) flat surface to complete the preparation.

In step S124, a phase change material plug is prepared in the first stress material layer.

Specifically, as shown in FIG. 6, combined with photolithography or other mask processes, pattern the surface of the first stress material layer 301 in the previous step to obtain a space for accommodating the phase change material plug 302, and prepare a phase change in the space Material plug post 302 .

The preparation of the phase change material plug 302 can generally be completed by magnetron sputtering, pulsed laser deposition, atomic layer deposition and other common semiconductor thin film deposition methods.

Optionally, the minimum distance between the cross-sectional edge of the first stress material layer 301 and the cross-sectional edge of the pattern is not less than 20 nm, to ensure sufficient volume change between the first stress material layer 301 and the phase change material plug 302, providing sufficient compressive stress.

Preferably, the minimum distance between the cross-sectional edge of the first stress material layer 301 and the cross-sectional edge of the phase change material plug 302 is a fixed value, so as to ensure that the compressive stress provided by the first stress material layer 301 for the phase change material plug 302 is Uniform, so that the activation energy change of the phase change material is uniform, thereby ensuring the stability of the power consumption of the phase change unit.

Step S13: A phase change material layer is prepared on the first insulating layer, and the other end of the phase change material plug is connected to the phase change material layer.

In some embodiments, step S13 may be combined with step S124 , that is, as shown in FIG. 7 , the phase change material plug posts 302 and the phase change material layer 400 are obtained by one deposition.

Step S14: preparing a second insulating layer on the phase change material layer, patterning the second insulating layer to obtain a second through hole, and preparing a top electrode plug in the second through hole, so that the One end of the top electrode plug is connected to the phase change material layer, and the projection of the phase change material plug and the top electrode plug on the substrate are not coincident.

In some embodiments, step S14 may include:

Step S141, preparing a second insulating layer on the phase change material layer.

Specifically, PECVD, magnetron sputtering, or ALD is used to grow a dense layer of other insulating materials such as silicon dioxide or aluminum oxide on the bottom electrode 200 as the second insulating layer 500, and the thickness can reach the micron level or more according to design requirements.

Step S142, patterning the second insulating layer to obtain second through holes.

Specifically, as shown in FIG. 8 , the pattern is transferred onto the second insulating layer 500 in combination with photolithography or other mask processes. Using the etching method, the second through hole is etched, and the depth of the etching should be skipped to ensure that the bottom electrode 200 can be exposed. The projection of the second through hole on the substrate 100 does not coincide with the projection of the first through hole on the substrate 100 to ensure that the projections of the phase change material plug 302 and the top electrode plug 502 on the substrate 100 do not coincide coincide.

In step S143, a top electrode plug post is prepared in the second through hole.

Specifically, the material of the top electrode 600 is filled into the first through hole by a method such as magnetron sputtering. The filling height is not lower than the depth of the second through hole, and after the peeling is completed, chemical mechanical polishing (CMP) is used to flatten the surface to complete the preparation.

In other embodiments, step S143 may also be as shown in FIG. 9 and FIG. 1 , firstly preparing the second stress material layer 501 in the second through hole, and then preparing the top electrode plug 502 . For the specific method, refer to step S123 and step S124, which will not be repeated here.

Step S15: A top electrode is prepared on the second insulating layer, and the other end of the top electrode plug is connected to the top electrode.

Optionally, the material of the top electrode 600 may be metal materials such as tungsten, titanium-tungsten, titanium-platinum, nickel-gold and the like.

In the embodiment of the present application, the projections of the phase change material plugs 302 and the top electrode plugs 502 on the substrate 100 do not overlap, so that there is a certain distance between the top electrode 600 and the bottom electrode 200 in a direction parallel to the substrate 100 , which can increase the current density in the phase change structure, reduce the temperature dissipation, and reduce the operating current.

The storage principle of the phase change memory is to use the Joule heat generated by the electric pulse to make the phase change memory material unit switch between a crystalline state with a lower resistance state and an amorphous state with a higher resistance state. The energy of switching between the crystalline state and the non-static state is called the activation energy of the phase change material. Applying physical stress to the phase change material can reduce the activation energy of the phase change material. A first stress material layer 301 is arranged around the phase change material plug 302. When the phase change material plug 302 is heated, since the thermal expansion coefficient of the thermal stress material is greater than that of the phase change material, there is a volume between the two. Therefore, the first stress material layer 301 will provide a compressive stress parallel to the direction of the substrate 100 for the phase change material plug 302, thereby reducing the activation energy of the phase change material and reducing the operating power consumption of the phase change memory cell. effect.

FIG. 10 is a flowchart of a method for fabricating a phase-change memory cell with low operating power consumption provided by an embodiment of the present invention, which is used to fabricate the phase-change memory cell shown in FIG. 2 . As shown in Figure 10, the difference between this method and the method shown in Figure 3 is:

In step S22, a first insulating layer 300 and a lower stress material layer 303 are first prepared on the bottom electrode 200, and the first insulating layer 300 and the lower stress material layer 303 are patterned to obtain a first through hole, and then the first through hole is formed on the bottom electrode 200. Phase change material plug posts 302 and a first stress material layer 301 are prepared in the first through holes.

In step S24, an upper stress material layer 503 and a second insulating layer 500 are first prepared on the phase change material layer 400, and the second insulating layer 500 and the upper stress material layer 503 are patterned to obtain a second through hole, and then a second through hole is formed on the phase change material layer 400. A top electrode plug 502 is prepared in the second through hole.

The remaining steps are the same as the method shown in FIG. 3 , and are not repeated here.

Since both the lower stress material layer 303 and the upper stress material layer 503 are in contact with the phase change material layer 400 , the action range of the compressive stress is expanded, so that the activation energy of the phase change material can be further reduced.

Optionally, the thicknesses of both the lower stress material layer 303 and the upper stress material layer 503 do not exceed 20 nm, so as to reduce the influence of deformation on the integrity of the phase change material unit.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. A phase-change memory cell with low operating power consumption, wherein the phase-change memory cell comprises: a substrate and a bottom electrode, a first insulating layer, a phase change material layer, a second insulating layer and a top electrode sequentially arranged on the substrate, The first insulating layer is provided with a phase change material plug, one end of the phase change material plug is connected to the phase change material layer, and the other end of the phase change material plug is connected to the bottom The electrodes are connected, a first stress material layer is arranged around the phase change material plug, the material of the first stress material layer is a thermal stress material, and the thermal expansion coefficient of the thermal stress material is larger than that of the phase change material the thermal expansion coefficient; The second insulating layer is provided with a top electrode plug, one end of the top electrode plug is connected to the phase change material layer, and the other end of the top electrode plug is connected to the top electrode, The projections of the phase change material plugs and the top electrode plugs on the substrate do not coincide. 2 . The phase change memory cell according to claim 1 , wherein a second stress material layer is provided around the top electrode plug, and the material of the second stress material layer is a thermal stress material. 3 . 3 . The phase change memory cell according to claim 2 , wherein the projection of the phase change material plug on the substrate is located at the projection of the second stress material layer on the substrate. 4 . Inside. 4. The phase-change memory cell according to any one of claims 1 to 3, wherein the phase-change memory cell further comprises: a lower stress material layer between the first insulating layer and the phase change material layer and an upper stress material layer between the second insulating layer and the phase change material layer, the upper stress material layer and the material of the lower stress material layer are all thermal stress materials. 5 . The phase change memory cell according to claim 1 , wherein the expansion coefficient of the thermal stress material is at least 1.5 times the thermal expansion coefficient of the phase change material. 6 . 6 . The phase change memory cell according to claim 1 , wherein the thermal stress material is benzocyclobutene. 7 . 7. A preparation method of a phase-change memory cell with low operating power consumption, characterized in that, forming a bottom electrode on the substrate; A first insulating layer is prepared on the bottom electrode, and the first insulating layer is patterned to obtain a first through hole, and a phase change material plug and a first stress material layer are prepared in the first through hole , one end of the phase change material plug is connected to the bottom electrode, the first stress material layer is arranged around the phase change material plug, and the material of the first stress material layer is thermal stress material, the thermal expansion coefficient of the thermal stress material is greater than the thermal expansion coefficient of the phase change material; preparing a phase change material layer on the first insulating layer, and the other end of the phase change material plug is connected to the phase change material layer; A second insulating layer is prepared on the phase change material layer, and the second insulating layer is patterned to obtain a second through hole, and a top electrode plug is prepared in the second through hole, and the top electrode One end of the plug post is connected to the phase change material layer, and the projections of the phase change material plug post and the top electrode plug post on the substrate are not coincident; A top electrode is prepared on the second insulating layer, and the other end of the top electrode plug is connected to the top electrode. 8 . The method for manufacturing a phase change memory cell according to claim 7 , wherein the method further comprises: preparing a second stress material layer in the second through hole, the second stress material layer surrounding the The periphery of the top electrode plug is arranged, and the material of the second stress material layer is a thermal stress material. 9 . The method for manufacturing a phase change memory cell according to claim 8 , wherein the projection of the phase change material plug on the substrate is located on the substrate of the second stress material layer. 10 . within the projection on. 10 . The method for manufacturing a phase change memory cell according to claim 7 , wherein the thermal expansion coefficient of the stress material is at least 1.5 times the thermal expansion coefficient of the phase change material. 11 .

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