Memory and heating electrode structure and preparation method thereof

Abstract

The invention discloses a memory and a heating electrode structure and a preparation method thereof, the heating electrode structure comprises a body, the body is formed by a cylinder, a part of side wall of the cylinder is removed from one end to the other end, and one end of the cylinder after the part of side wall is removed has an end face area smaller than that of the other end. The body is used for being in contact with a resistor through the end face of the end, with the smaller area, of the cylinder body with part of the side wall removed. According to the invention, the contact area between the heating electrode structure and the resistor can be obviously reduced, and the memory can be prepared by adopting a conventional CMOS (Complementary Metal Oxide Semiconductor) process, so that the energy consumption can be effectively reduced, and the device performance can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor integrated circuit processes, and particularly to a memory, a heating electrode structure thereof, and a preparation method thereof. Background Art

[0002] The difference in conductivity exhibited when a chalcogenide, for example, undergoes a phase change between a crystalline state and an amorphous state can be used to store data. In the memory storage cells formed in this way, a heating electrode is usually used to contact the chalcogenide resistive material. When current passes through, Joule heat is generated. When the temperature reaches the phase change threshold of the resistive material, the resistive material will undergo a phase change between the crystalline state and the amorphous state. By miniaturizing the device size and improving the heating efficiency of the phase change region between the crystalline state and the amorphous state, the operating power consumption of the memory can be effectively reduced. And by reducing the contact area between the heating electrode and the resistive material, a good heating effect can be obtained. Therefore, reducing the size of the heating electrode is the key to reducing power consumption.

[0003] The traditional storage cell has a "T-shaped" structure, that is, a cylindrical heating electrode is used to contact the resistive material, and its contact surface is "circular". To reduce the contact area between the heating electrode and the resistive material, the heating electrode material can be deposited on the inner wall of a cylindrical hole to form an annular electrode. In this storage cell, the contact surface between the heating electrode and the resistive material is "circular annular". Compared with the "T-shaped" structure, its contact area is reduced and the power consumption is reduced.

[0004] To obtain a storage cell with lower power consumption, it is necessary to continuously reduce the contact area between the heating electrode and the resistive material. By reducing the thickness of the above-mentioned annular heating electrode and the size of the ring, the contact area between the heating electrode and the resistive material can be reduced. However, if the electrode thickness is too thin, there is a risk of open circuit. In addition, to reduce the circumference of the ring of the heating electrode, the diameter of the cylindrical hole where it is located needs to be reduced, which poses relatively stringent requirements on the lithography and etching processes.

[0005] Therefore, it is necessary to optimize the existing annular heating electrode to further reduce the contact area between the heating electrode and the resistive material, thereby further reducing the energy consumption. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art, and provide a memory, a heating electrode structure thereof, and a preparation method thereof.

[0007] To achieve the above purpose, the technical solution of the present invention is as follows:

[0008] The present invention provides a heating electrode structure, including a body formed by a cylinder. The cylinder removes a part of its side wall from one end to the other end, so that one end of the cylinder after removing the part of the side wall has an end face area smaller than that of the other end. The body is used to contact a resistor with the end face of the cylinder with a smaller area after removing the part of the side wall.

[0009] Further, the cylinder obliquely cuts from a first side position outside one end face of the cylinder to a second side position opposite to the other end of the cylinder until it penetrates through the cylinder to remove a part of the side wall; or, the cylinder longitudinally cuts from a first side position inside one end face of the cylinder to a distance greater than zero from the end face of the other end of the cylinder, and then transversely cuts to a second side position opposite to the other end of the cylinder until it penetrates through the cylinder to remove a part of the side wall.

[0010] Further, a first included angle between the oblique cutting direction and the radial direction of the cylinder is 45 to 80 degrees; or, a second included angle between the longitudinal cutting direction and the radial direction of the cylinder is 45 to 90 degrees.

[0011] Further, the end face of one end of the cylinder is also lowered after the cylinder removes a part of the side wall; and / or, one end of the cylinder is an open end, and the other end of the cylinder is a closed end.

[0012] The present invention also provides a memory, including a storage unit. The storage unit includes a bottom electrode, a resistor, a top electrode, and the above heating electrode structure. The heating electrode structure contacts the resistor with one end of the cylinder after removing a part of the side wall through the body, and contacts the bottom electrode with the other end of the cylinder after removing a part of the side wall through the body. The top electrode is connected to the resistor.

[0013] Further, it includes two adjacent storage units, and the bodies of the heating electrode structures in the two storage units are arranged relatively and symmetrically with the sides where the side walls are removed of their respective cylinders.

[0014] The present invention also provides a method for manufacturing a heating electrode structure, including:

[0015] Providing a substrate having two adjacent bottom electrodes;

[0016] Forming a first dielectric layer on the substrate;

[0017] Forming two through holes respectively communicating with the two bottom electrodes in the first dielectric layer;

[0018] Forming an electrode material layer on the inner wall of the through hole, and performing dielectric filling and planarization on the through hole;

[0019] Form a trench lithography pattern on the surface of the first dielectric layer, exposing the top surfaces of the two through holes;

[0020] Etch the two through holes through the trench lithography pattern, removing the electrode material layer on the partial side walls of the two through holes within the trench lithography pattern, forming a trench within the outer side walls away from each other of the two through holes below the surface of the first dielectric layer, and retaining the electrode material layer on the bottom surfaces of the two through holes;

[0021] Perform dielectric filling and planarization on the trench, forming two heating electrode structures respectively connecting the two bottom electrodes from the remaining electrode material layer, and exposing the tops of the heating electrode structures.

[0022] Further, after planarizing the through holes, the relationship between the remaining thickness h of the first dielectric layer and the diameter d of the bottom electrode is: h / d = tan 45° to tan 80°; when forming the trench lithography pattern, the opening pitch X of the trench lithography pattern is greater than or equal to the distance x2 between the distal ends of the two through holes; when etching the two through holes, the side walls of the formed trench are inclined at an angle α1 of 45° to 80° with respect to the horizontal direction; when planarizing the trench, adjust the exposed area of the top of the heating electrode structure by controlling the polishing amount during planarization.

[0023] Further, after planarizing the through holes, the relationship between the remaining thickness h of the first dielectric layer and the diameter d of the bottom electrode is: h / d = tan 45° to tan 80°; when forming the trench lithography pattern, the opening pitch X of the trench lithography pattern is greater than the distance x1 between the proximal ends of the two through holes and less than the distance x2 between the distal ends of the two through holes; when etching the two through holes, the side walls of the formed trench are inclined at an angle α2 of 45° to 90° with respect to the horizontal direction.

[0024] The present invention further provides a method for manufacturing a memory, including, after performing the above-mentioned method for manufacturing a heating electrode structure, further including:

[0025] Form two resistors respectively on the tops of the two heating electrode structures on the surface of the first dielectric layer;

[0026] Form a second dielectric layer on the surface of the first dielectric layer, covering the resistors;

[0027] Form two top electrodes respectively connecting the two resistors at the bottoms on the surface of the second dielectric layer.

[0028] As can be seen from the above technical solution, in the present invention, by removing a part of the side wall of the cylinder body forming the heating electrode structure body from one end to the other end, and contacting one end of the cylinder body after removing the part of the side wall with the resistor in the memory, the contact area between the heating electrode structure and the resistor can be significantly reduced, that is, the area of the conversion region between the crystalline state and the amorphous state in the resistor can be reduced, and the memory can be fabricated using a conventional CMOS process. Therefore, the energy consumption can be effectively reduced and the device performance can be improved. In addition, the contact area between the heating electrode structure and the resistor can be adjusted by performing a surface lowering adjustment on one end face of the cylinder body, thereby increasing the flexibility of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. 6 is a side view of a heating electrode structure according to a first preferred embodiment of the present invention.

[0030] Figure 2 FIG. 10 is a cross-sectional view of a heating electrode structure according to a first preferred embodiment of the present invention.

[0031] Figure 3 FIG. 14 is a side view of a heating electrode structure according to a second preferred embodiment of the present invention.

[0032] Figure 4 FIG. 18 is a cross-sectional view of a heating electrode structure according to a second preferred embodiment of the present invention.

[0033] Figure 5 FIG. 22 is a schematic structural diagram of a memory according to a first preferred embodiment of the present invention.

[0034] Figure 6 FIG. 26 is a schematic structural diagram of a memory according to a second preferred embodiment of the present invention.

[0035] Figures 7 - 14 FIG. 30 is a schematic diagram of the process steps of a method for fabricating a memory according to a first preferred embodiment of the present invention.

[0036] Figures 15 - 19 FIG. 34 is a schematic diagram of the process steps of a method for fabricating a memory according to a second preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present invention pertains. The words such as "including" used herein are intended to mean that the elements or items appearing before this word cover the elements or items listed after this word and their equivalents, without excluding other elements or items.

[0038] The following further elaborates on the specific implementation manners of the present invention in conjunction with the accompanying drawings.

[0039] Reference Figures 1 - 2 A heating electrode structure 20 of the present invention includes a body 22. The body 22 is formed by a cylindrical body 21. The cylindrical body 21 removes a part of the side wall from one end (shown as the upper end in the figure) to the other end (shown as the lower end), that is, the body 22 is formed by the remaining cylindrical part of the complete cylindrical body 21 (as shown by the rectangular contour graph formed by combining the body 22 represented by a solid line and the dashed box in Figure 1 ). After removing a part of the side wall from the upper end to the lower end.

[0040] The upper end of the cylindrical body 21 after removing a part of the side wall has an end face area smaller than that of the lower end. The body 22 is used to contact a phase change resistor in, for example, a phase change memory with the upper end face of the cylindrical body 21 after removing a part of the side wall to heat the phase change resistor, so that the phase change resistor undergoes a phase change between the crystalline state and the amorphous state. Since a part of the side wall at the upper end of the body 22 is removed, the body 22 has a relatively smaller upper end (area) compared to the lower end. Therefore, the contact area between the heating electrode structure 20 and the phase change resistor can be significantly reduced, that is, the area of the conversion region between the crystalline state and the amorphous state in the phase change resistor is reduced, the heating efficiency is improved, and the energy consumption is reduced.

[0041] In some embodiments, the cylindrical body 21 is obliquely cut from a first side position outside the upper end face (that is, any position on the horizontal extension line extending rightward outside the upper end face of the cylindrical body 21 shown in the figure) to a second side position opposite to the lower end of the cylindrical body 21, and is obliquely cut from the starting point A at the upper end of the cylindrical body 21 to the ending point D when passing through the cylindrical body 21, so as to remove a part of the side wall on the second side shown in the figure to form the body 22. It can be understood that the starting point A can be located at the endpoint on the right side (the first side) of the upper end of the cylindrical body 21, or can be located on the side wall on the right side of the upper end of the cylindrical body 21 (the starting point A shown in the figure is the case when it coincides with the endpoint on the right side of the upper end of the cylindrical body 21).

[0042] Further, the first included angle α1 between the above-mentioned oblique cutting direction and the radial direction (perpendicular to the axial direction of the cylinder body 21) of the cylinder body 21 is 45 to 80 degrees. Figure 2 The oblique cutting direction is represented by the oblique dotted line a (i.e., the direction of the AD connection line). It can be understood that according to the different magnitudes of the oblique cutting angle (the first included angle α1), the end point D when obliquely cutting through the cylinder body 21 can be located on the side wall of the cylinder body 21 at the second side position, or can be located on the lower end face of the cylinder body 21 at the second side position. That is, the lower end (point D) of the oblique dotted line a moves to the right when the oblique cutting angle increases, and conversely, the lower end of the oblique dotted line a moves to the left when the oblique cutting angle decreases. Since the starting point A of the oblique cutting is located at the right end point or the right side wall at the upper end of the cylinder body 21, the cylinder body 21 has a sharp new upper end after oblique cutting, like the shape of a "syringe needle tip".

[0043] In some embodiments, the upper end face of the cylinder body 21 is an open end; the lower end face of the cylinder body 21 is a closed end. The body 22 is further used to contact the bottom electrode in the memory with the closed lower end of the cylinder body 21 after removing part of the side wall. Since the body 22 has a closed lower end, the contact area between the heating electrode structure 20 and the bottom electrode can be fully guaranteed, and the contact resistance can be reduced.

[0044] In some embodiments, after the cylinder body 21 for forming the body 22 is obliquely cut to remove part of the side wall, the upper end face of the cylinder body 21 is further lowered. That is, the sharp upper end originally possessed by the cylinder body 21 is cut by a certain height L in the horizontal direction, so as to form a new upper end with a certain area, as Figure 1 shown. It can be seen that after the surface of the cylinder body 21 is lowered, the overall height of the cylinder body 21 drops from point A shown in the figure to point B, and the magnitude of the cutting height L between point A and point B is proportional to the area of the new upper end face of the cylinder body 21 after the surface is lowered. Therefore, by cutting the sharp upper end originally possessed by the cylinder body 21 by a certain height L, the contact area between the heating electrode structure 20 and the phase change resistor can be adjusted, thus solving the problem that the miniaturization of the traditional circular ring heating electrode requires reducing the size of the circular hole where it is located, and the size of the circular hole is limited by the process manufacturing capacity.

[0045] Refer to Figures 3 - 4 . Different from the above embodiments, in a heating electrode structure 20 of this embodiment, the cylinder body 21 for forming the body 22 is longitudinally cut from the first side position within the upper end face (i.e., the position on the upper end face having a certain distance M greater than zero from the right outer side wall of the cylinder body 21 at the first side position) to point E shown in the figure at a distance greater than zero from the end face of the lower end of the cylinder body 21, and then transversely cut to point D where it penetrates through the cylinder body 21 at the opposite second side position, thereby removing part of the side wall on the second side.

[0046] In some embodiments, the second included angle α2 between the longitudinal cutting direction and the radial direction of the cylinder 21 (the second included angle α2 faces the outer side wall of the cylinder 21 on the longitudinal cutting side) is 45 to 90 degrees.

[0047] In the figure, the vertical dotted line b and the horizontal dotted line c represent the orientations during longitudinal cutting and transverse cutting, and the corresponding second included angle α2 is 90 degrees at this time. It can be understood that regardless of the size of the longitudinal cutting angle (the second included angle α2), the end point D when longitudinally cutting and then transversely cutting through the cylinder 21 is located on the side wall of the cylinder 21 at the second side position. Among them, the lower end E of the vertical dotted line b moves to the right when the longitudinal cutting angle increases, and conversely, the lower end E of the vertical dotted line b moves to the left when the longitudinal cutting angle decreases. However, in any case, since the starting point A during longitudinal cutting is located inside the upper end face of the cylinder 21 (i.e., the position inside the outer side wall on the right side of the upper end of the cylinder 21), the cylinder 21 has a flat upper end with a certain area after longitudinal cutting, and this flat upper end is formed by the top surface of the side wall on the upper right side of the cylinder 21 that is not cut off. And, after transverse cutting, the closed lower end of the cylinder 21 is completely retained. The side wall of the cylinder 21 at the second side position can be partially retained, but because its height is lower than the height of the side wall on the right side, it will not contact the phase change resistor and thus does not participate in the direct heating of the phase change resistor. Therefore, the heating electrode structure 20 of this embodiment also has a relatively small heating contact area with the upper end smaller than the lower end.

[0048] It can be seen that the area size of the upper end face of the main body 22 (the cylinder 21) of the heating electrode structure 20 for contacting the phase change resistor is mainly related to the size of the distance M from the starting point A during longitudinal cutting to the outer side wall of the cylinder 21 at the first side position, and the area size when the top of the heating electrode structure 20 contacts the phase change resistor can also be adjusted by reducing the surface of the upper end of the cylinder 21.

[0049] Reference Figures 5 - 6 . A memory of the present invention is a phase change memory, and the phase change memory includes phase change memory cells. Illustrated is a case where, for example, the phase change memory is provided with 2 phase change memory cells, but it is not limited thereto. Each phase change memory cell includes a bottom electrode 10, a phase change resistor 30, a top electrode 40, and the heating electrode structure 20 of the present invention described above. Among them, the heating electrode structure 20 can adopt the corresponding heating electrode structure 20 as described above Figures 1 - 2 , such as Figure 5 shown. The heating electrode structure 20 can also adopt the corresponding heating electrode structure 20 as described above Figures 3 - 4 , such as Figure 6As shown. The heating electrode structure 20 contacts the phase change material at the bottom of the phase change resistor 30 through the upper end of the cylinder 21 after removing a part of the side wall by the body 22. The heating electrode structure 20 contacts the top of the bottom electrode 10 through the lower end of the cylinder 21 after removing a part of the side wall by the body 22. The top electrode 40 is connected to the top of the phase change resistor 30. The phase change memory cell is built on a substrate (not shown) and is disposed in the dielectric layer 50.

[0050] In some embodiments, the phase change memory includes two adjacent phase change memory cells on the left and right. The bodies 22 of the heating electrode structures 20 in the two phase change memory cells are oppositely disposed on one side (the second side) of the respective cylinders 21 with the removed side walls. Among them, the bodies 22 of the two heating electrode structures 20 may have the same shape and size and are mirror-symmetrically disposed.

[0051] In some embodiments, the upper ends of the bodies 22 (cylinders 21) of the two heating electrode structures 20 may be partially removed (lowered) to adjust the size of the contact area between the body 22 of the heating electrode structure 20 and the phase change material according to the height of the removed part.

[0052] In some embodiments, the dielectric layer 50 includes a front dielectric layer 51, an isolation dielectric layer 52, a first dielectric layer 53, and a second dielectric layer 54. A filling dielectric 60 is provided between the two heating electrode structures 20, and the filling dielectric 60 uses the same material as the first dielectric layer 53. The top electrode 40 includes a first top electrode 41 and a second top electrode 42.

[0053] For the materials of the bottom electrode 10, the phase change resistor 30, the top electrode 40, the dielectric layer 50, and the heating electrode structure 20 in the phase change memory of the present invention above, the materials of the bottom electrode, the phase change resistor, the top electrode, the dielectric layer, and the heating electrode in the conventional phase change memory are used. The substrate can be a common substrate suitable for forming a phase change memory, and reference can be made to the prior art.

[0054] The following further details a memory manufacturing method of the present invention including a method for manufacturing a heating electrode structure through specific embodiments and in combination with the drawings.

[0055] Refer to Figures 7 - 15 . A memory manufacturing method of the present invention can be used to manufacture, for example, Figure 5 a phase change memory of the present invention as shown, which contains, for example, Figures 1 - 2 a heating electrode structure 20 of the present invention as shown, and includes the following steps:

[0056] Step S11: Provide a substrate having two adjacent bottom electrodes 10.

[0057] As Figure 7As shown, a silicon substrate (not shown) is provided. A front dielectric layer 51 is formed on the silicon substrate. Two adjacent bottom electrodes 10 connected to the silicon substrate are formed in the front dielectric layer 51 as an example, and two phase change memory cells are further formed on the two bottom electrodes 10. The bottom electrode 10 can be, for example, a tungsten via electrode.

[0058] Step S12: Form a first dielectric layer 53 on the substrate.

[0059] As Figure 7 shown, a silicon nitride isolation dielectric layer 52 is formed on the surface of the front dielectric layer 51 by a deposition process to cover the bottom electrode 10.

[0060] Then, a silicon dioxide first dielectric layer 53 is formed on the surface of the isolation dielectric layer 52 by a deposition process. The relationship between the thickness H of the first dielectric layer 53 and the diameter d of the bottom electrode 10 is: H / d > tan80°.

[0061] Step S13: Form two through holes 531 that respectively communicate with the two bottom electrodes 10 in the first dielectric layer 53.

[0062] As Figure 8 shown, two through holes 531 that penetrate through the isolation dielectric layer 52 and communicate with the tops of the two bottom electrodes 10 are formed downward on the surface of the first dielectric layer 53 by a photolithography and etching process.

[0063] Step S14: Form an electrode material layer 201 on the inner wall of the through hole 531, and perform dielectric filling and planarization on the through hole 531.

[0064] As Figure 9 shown, an electrode material layer 201 for preparing the heating electrode structure 20 is grown on the inner wall of the through hole 531 by a chemical vapor deposition or atomic layer deposition technique. The material of the electrode material layer 201 is any one of TiN, TiSiN, and TiON; the thickness of the electrode material layer 201 is 2 nm to 10 nm.

[0065] Then, a silicon dioxide dielectric 61 is filled into the through hole 531 by a high aspect ratio process, and chemical mechanical polishing is used for planarization to expose the surface of the first dielectric layer 53 and the top of the electrode material layer 201. That is, a ring structure corresponding to Figures 1 - 2 the cylinder 21 is formed.

[0066] The remaining thickness of the first dielectric layer 53 after planarization is h, and it has a trigonometric function relationship with the diameter d of the bottom electrode 10, such that the value range of h / d is between tan 45° and tan 80°.

[0067] Step S15: Form a trench photolithography pattern 70 on the surface of the first dielectric layer 53, exposing the top surfaces of the two through holes 531.

[0068] As Figure 10 shown, use a photolithography process to form a trench photolithography pattern 70 on the surface of the first dielectric layer 53, exposing the top surfaces of the two through holes 531.

[0069] When forming the trench photolithography pattern 70, make the opening pitch X of the trench photolithography pattern 70 greater than or equal to the pitch x2 between the distal ends of the two through holes 531, and make the trench photolithography pattern 70 completely cover the two through holes 531. The pitch between the proximal ends of the two through holes 531 is denoted as x1.

[0070] Step S16: Etch the two through holes 531 through the trench photolithography pattern 70, remove the electrode material layer 201 on the partial side walls of the two through holes 531 within the trench photolithography pattern 70, form a trench 80 within the outer side walls away from each other of the two through holes 531 below the surface of the first dielectric layer 53, and retain the electrode material layer 201 on the bottom surfaces of the two through holes 531.

[0071] As Figure 11 shown, use an etching process and etch downward through the trench photolithography pattern 70, that is, etch the two through holes 531. Through etching, remove the electrode material layer 201 on the partial side walls of the two through holes 531 within the trench photolithography pattern 70, form a trench 80 below the surface of the first dielectric layer 53, with the bottom located within the outer side walls away from each other of the two through holes 531 and the top located outside the outer side walls away from each other of the two through holes 531, and retain at least part of the electrode material layer 201 on the bottom surfaces of the two through holes 531. In this embodiment, use an etching process in which the two sides of the top of the trench 80 correspond to the top positions of the outer side walls away from each other of the two through holes 531 to form a chamfering of the two through holes 531, that is, the starting point of the chamfering corresponds to Figures 1 - 2 the starting point A in

[0072] When etching the two through holes 531, it is necessary to adjust the etching parameters so that the side wall of the trench 80 formed by etching forms an inclination angle α1 of 45° to 80° with the horizontal direction (corresponding to Figures 1 - 2 the first included angle α1 during the chamfering of the cylinder body 21).

[0073] It should be noted that Figure 11 is an ideal situation where the etching depth of the trench 80 just reaches the top of the bottom electrode 10. When the thickness h of the first dielectric layer 53 and the diameter d of the bottom electrode 10 are fixed, the selection of the inclination angle α1 of the trench 80 does not need to exactly satisfy tanα1 = h / d. Figure 11This is only a relatively ideal etching solution. Because in this case, it can provide a suitable process window for subsequent planarization of the top of the heating electrode structure, and it is not easy to cause etching damage to the bottom electrode 10 when etching the trench 80.

[0074] After etching the trench 80, a heating electrode structure 20 (body 22) with a sharp upper end is formed on each of the two bottom electrodes 10. Figure 11 Shows the cross-sectional structure of the heating electrode structure 20 formed after etching. Figure 12 Shows the side structure of the heating electrode structure 20 formed after etching. In order to adjust the contact area between the heating electrode structure 20 and the phase change resistor 30 formed subsequently, the size of the upper end of the heating electrode structure 20 can also be correspondingly adjusted by performing a planarization and lowering process on the sharp upper end of the heating electrode structure 20. For details, see the following step S17.

[0075] Step S17: Fill the trench 80 with a dielectric and planarize it, and form two heating electrode structures 20 respectively connecting the two bottom electrodes 10 from the remaining electrode material layer 201, and expose the top of the heating electrode structure 20.

[0076] As Figure 13 shown, then, using a high aspect ratio process, fill the trench 80 with a silicon dioxide dielectric 60, and perform chemical mechanical polishing planarization to perform a lowering process on the sharp upper end of the heating electrode structure 20, exposing the surface of the first dielectric layer 53 and the top of the electrode material layer 201 (heating electrode structure 20). That is, a body 22 with a lowered upper end corresponding to Figures 1 - 2 is formed.

[0077] When planarizing the trench 80, by controlling the polishing amount during planarization, the exposed area of the top of the heating electrode structure 20 is adjusted, so as to form a heating electrode structure 20 with a desired contact area. The contact area can be adjusted through the lowering process, preventing subsequent problems of poor contact with the phase change material. Among them, the larger the inclination angle α1 of the trench 80, the larger the process window of the chemical mechanical polishing planarization.

[0078] The method for preparing the heating electrode structure of the present invention includes the above steps.

[0079] Step S18: Form two phase change resistors 30 respectively on the tops of the two heating electrode structures 20 on the surface of the first dielectric layer 53.

[0080] As Figure 14 shown, using a deposition process, a phase change material layer and a titanium nitride layer are sequentially formed on the surface of the first dielectric layer 53.

[0081] Then, a photolithography and etching process is adopted to pattern the phase change material layer and the titanium nitride layer, and a phase change resistor 30 and a first top titanium nitride electrode 41 located on the phase change resistor 30 are respectively formed on the top of the two heating electrodes.

[0082] Step S19: A second dielectric layer 54 is formed on the surface of the first dielectric layer 53 to cover the phase change resistor 30.

[0083] As Figure 14 shown, then, a high aspect ratio deposition process is adopted to form a second dielectric layer 54 of silicon dioxide on the surface of the first dielectric layer 53 to completely cover the phase change resistor 30 and the first top electrode 41 therein. Then, chemical mechanical polishing planarization is performed to obtain a flat surface of the second dielectric layer 54 and keep a certain distance from the top of the first top electrode 41.

[0084] Step S20: Two top electrodes 40 with bottoms respectively connected to the two phase change resistors 30 are formed on the surface of the second dielectric layer 54.

[0085] As Figure 14 shown, then, a photolithography and etching process is adopted to form two through holes with bottoms respectively communicating with the tops of the two first top electrodes 41 on the surface of the second dielectric layer 54 corresponding to the positions of the two phase change resistors 30 (the first top electrodes 41).

[0086] Finally, the through holes are filled with metal to form two second top electrodes 42 with bottoms respectively connected to the tops of the two first top electrodes 41, so that the two top electrodes 40 with bottoms respectively connected to the two phase change resistors 30 are formed by the second top electrodes 42 and the first top electrodes 41.

[0087] Refer to Figures 15 - 19 and combine with reference Figures 7 - 10 . A method for manufacturing a memory of the present invention can be used to manufacture a phase change memory of the present invention as shown in Figure 6 for example, which contains a heating electrode structure 20 of the present invention as shown in Figures 3 - 4 for example, and includes the following steps:

[0088] Step S21: Provide a substrate having two adjacent bottom electrodes 10.

[0089] Step S22: Form a first dielectric layer 53 on the substrate.

[0090] Step S23: Form two through holes 531 respectively communicating with the two bottom electrodes 10 in the first dielectric layer 53.

[0091] Step S24: Form an electrode material layer 201 on the inner wall of the through hole 531, and perform dielectric filling and planarization on the through hole 531.

[0092] Steps S21 to S24 are the same as steps S11 to S14 above. Please refer to the foregoing embodiments and Figures 7 - 9 understand them accordingly, and no further elaboration will be provided.

[0093] Step S25: Form a trench lithography pattern 70 on the surface of the first dielectric layer 53, exposing the top surfaces of the two through holes 531.

[0094] As Figure 15 shown, use a lithography process to form a trench lithography pattern 70 on the surface of the first dielectric layer 53, exposing the top surfaces of the two through holes 531.

[0095] When forming the trench lithography pattern 70, make the opening spacing X of the trench lithography pattern 70 greater than the spacing x1 between the proximal ends of the two through holes 531 and less than the spacing x2 between the distal ends of the two through holes 531; and make the opening of the trench lithography pattern 70 within the distal ends of the two through holes 531, and at a certain distance from the distal ends of the two through holes 531 (i.e., Figure 3 the distance M in).

[0096] Step S26: Etch the two through holes 531 through the trench lithography pattern 70, removing the electrode material layer 201 on the partial side walls of the two through holes 531 within the trench lithography pattern 70, forming a trench 80 within the outer side walls away from each other of the two through holes 531 below the surface of the first dielectric layer 53, and retaining the electrode material layer 201 on the bottom surfaces of the two through holes 531.

[0097] As Figure 16 shown, use an etching process and etch downward through the trench lithography pattern 70, that is, etch the two through holes 531. Through etching, remove the electrode material layer 201 on the partial side walls of the two through holes 531 within the trench lithography pattern 70, form a trench 80 whose bottom and top are both within the outer side walls away from each other of the two through holes 531 below the surface of the first dielectric layer 53, and retain all of the electrode material layer 201 on the bottom surfaces of the two through holes 531.

[0098] When etching the two through holes 531, it is necessary to adjust the etching parameters so that the side walls of the etched trench 80 form an inclination angle α2 of 45° to 90° with the horizontal direction (corresponding to Figures 3 - 4 the second included angle α2 when the cylinder 21 is longitudinally cut).

[0099] It should be noted that Figure 16 this is also an ideal etching situation. At this time, the optimal inclination angle α2 is 90°, and no etching damage is caused to the bottom electrode 10. Since this solution has high requirements for the lithography size and overlay accuracy of the trench 80, it can be used as an alternative solution.

[0100] After the trench 80 is etched, a heating electrode structure 20 with a certain area at the top (upper end) is formed on each of the two bottom electrodes 10 respectively. Figure 16 The cross-sectional structure of the heating electrode structure 20 formed after etching is shown, Figure 17 The side structure of the heating electrode structure 20 formed after etching is shown.

[0101] Step S27: Fill and planarize the trench 80, form two heating electrode structures 20 respectively connecting the two bottom electrodes 10 from the remaining electrode material layer 201, and expose the top of the heating electrode structure 20.

[0102] As Figure 18 shown, then, using a high aspect ratio process, fill the trench 80 with silicon dioxide dielectric 60, and perform chemical mechanical polishing planarization to perform a surface lowering treatment on the upper end of the heating electrode structure 20, exposing the surface of the first dielectric layer 53 and the top of the electrode material layer 201 (heating electrode structure 20). That is, a body 22 corresponding to Figures 3 - 4 and with the upper end subjected to surface lowering treatment is formed.

[0103] When planarizing the trench 80, by controlling the polishing amount during planarization, the height of the heating electrode structure 20 is adjusted, so as to form a heating electrode structure 20 with a required height. However, in this method, by controlling the polishing amount, the influence on the exposed area of the top of the heating electrode structure 20 is relatively small.

[0104] A method for preparing a heating electrode structure according to the present invention includes the above steps S21 to S27.

[0105] Step S28: Form two phase change resistors 30 respectively on the tops of the two heating electrode structures 20 on the surface of the first dielectric layer 53.

[0106] As Figure 19 shown, using a deposition process, a phase change material layer and a titanium nitride layer are sequentially formed on the surface of the first dielectric layer 53.

[0107] Then, using a photolithography and etching process, pattern the phase change material layer and the titanium nitride layer, and form a phase change resistor 30 and a first titanium nitride top electrode 41 located on the phase change resistor 30 on the top of each of the two heating electrode structures 20.

[0108] Step S29: Form a second dielectric layer 54 on the surface of the first dielectric layer 53 to cover the phase change resistor 30.

[0109] As Figure 19As shown, then, using a high aspect ratio deposition process, a second silicon dioxide dielectric layer 54 is formed on the surface of the first dielectric layer 53, completely covering the phase change resistor 30 and the first top electrode 41 therein. After that, chemical mechanical polishing planarization is performed to obtain a flat surface of the second dielectric layer 54 and a certain distance from the top of the first top electrode 41.

[0110] Step S30: Two top electrodes 40 are formed on the surface of the second dielectric layer 54, with the bottoms respectively connected to the two phase change resistors 30.

[0111] As Figure 19 shown, then, using a photolithography and etching process, two through holes are formed on the surface of the second dielectric layer 54 corresponding to the positions of the two phase change resistors 30 (the first top electrode 41), with the bottoms respectively communicating with the tops of the two first top electrodes 41.

[0112] Finally, the through holes are filled with metal to form two second top electrodes 42 with the bottoms respectively connected to the tops of the two first top electrodes 41, so that the two top electrodes 40 with the bottoms respectively connected to the two phase change resistors 30 are formed by the second top electrodes 42 and the first top electrodes 41.

[0113] In summary, in the present invention, by removing a part of the side wall of the cylinder 21 forming the main body 22 of the heating electrode structure 20 from the upper end to the lower end, and making the upper end of the cylinder 21 after removing the part of the side wall contact the phase change resistor in the phase change memory, the contact area between the heating electrode structure 20 and the phase change resistor can be significantly reduced, that is, the area of the conversion region between the crystalline state and the amorphous state in the phase change resistor is reduced, and the phase change memory can be fabricated using a conventional CMOS process. Therefore, the energy consumption can be effectively reduced and the device performance can be improved. In addition, the contact area between the heating electrode structure 20 and the phase change resistor can be adjusted by performing a surface lowering adjustment on the upper end face of the cylinder 21, thereby increasing the flexibility of the process.

[0114] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention described in the claims. Moreover, the present invention described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A heating electrode structure, characterized in that, it includes a body, the body is formed by a cylinder, the cylinder removes part of its side wall from one end to the other end, so that one end of the cylinder after removing part of the side wall has an end face area smaller than that of the other end, and the body is used to contact the resistor with the end face of the cylinder with a smaller area after removing part of the side wall.

2. The heating electrode structure according to claim 1, characterized in that, the cylinder obliquely cuts from a first side position outside one end face to a second side position opposite to the other end of the cylinder until it penetrates the cylinder to remove part of the side wall; or, the cylinder longitudinally cuts from a first side position inside one end face to a distance greater than zero from the end face of the other end of the cylinder, and then transversely cuts to a second side position opposite to penetrate the cylinder to remove part of the side wall.

3. The heating electrode structure according to claim 2, characterized in that, the first included angle between the oblique cutting direction and the radial direction of the cylinder is 45 to 80 degrees; or, the second included angle between the longitudinal cutting direction and the radial direction of the cylinder is 45 to 90 degrees.

4. The heating electrode structure according to claim 1, characterized in that, one end face of the cylinder is also lowered after the cylinder removes part of the side wall; and / or, one end of the cylinder is an open end, and the other end of the cylinder is a closed end.

5. A memory, characterized in that, it includes a storage unit, the storage unit includes a bottom electrode, a resistor, a top electrode, and the heating electrode structure according to any one of claims 1-4, the heating electrode structure contacts the resistor through one end of the cylinder after removing part of the side wall of the body, the heating electrode structure contacts the bottom electrode through the other end of the cylinder after removing part of the side wall of the body, and the top electrode is connected to the resistor.

6. The memory according to claim 5, characterized in that, it includes two adjacent storage units, and the bodies of the heating electrode structures in the two storage units are arranged relatively and symmetrically with the sides where the side walls are removed of their respective cylinders.

7. A method for preparing a heating electrode structure, characterized in that, it includes: providing a substrate having two adjacent bottom electrodes; forming a first dielectric layer on the substrate; forming two through holes in the first dielectric layer that respectively communicate with the two bottom electrodes; forming an electrode material layer on the inner walls of the through holes, and performing dielectric filling and planarization on the through holes; forming a trench lithography pattern on the surface of the first dielectric layer to expose the top surfaces of the two through holes; etching the two through holes through the trench lithography pattern, removing the electrode material layer on the partial side walls of the two through holes within the trench lithography pattern, forming a trench within the outer side walls away from each other of the two through holes below the surface of the first dielectric layer, and retaining the electrode material layer on the bottom surfaces of the two through holes; Perform dielectric filling and planarization on the trench, form two heating electrode structures respectively connecting the two bottom electrodes from the remaining electrode material layer, and expose the top of the heating electrode structures.

8. The method for preparing a heating electrode structure according to claim 7, wherein, after planarizing the through hole, the relationship between the remaining thickness h of the first dielectric layer and the diameter d of the bottom electrode is: h / d = tan 45° to tan 80°; when forming the trench lithography pattern, make the opening pitch X of the trench lithography pattern greater than or equal to the pitch x2 between the distal ends of the two through holes; when etching the two through holes, make the side wall of the trench formed by etching form an inclination angle α1 of 45° to 80° with the horizontal direction; when planarizing the trench, adjust the exposed area of the top of the heating electrode structure by controlling the grinding amount during planarization.

9. The method for preparing a heating electrode structure according to claim 7, wherein, after planarizing the through hole, the relationship between the remaining thickness h of the first dielectric layer and the diameter d of the bottom electrode is: h / d = tan 45° to tan 80°; when forming the trench lithography pattern, make the opening pitch X of the trench lithography pattern greater than the pitch x1 between the proximal ends of the two through holes and less than the pitch x2 between the distal ends of the two through holes; when etching the two through holes, make the side wall of the trench formed by etching form an inclination angle α2 of 45° to 90° with the horizontal direction.

10. A method for manufacturing a memory, wherein, including, after performing the method for preparing a heating electrode structure according to any one of claims 7-9, further including: forming two resistors respectively on the tops of the two heating electrode structures on the surface of the first dielectric layer; forming a second dielectric layer on the surface of the first dielectric layer to cover the resistors; forming two top electrodes respectively connected to the two resistors at the bottom on the surface of the second dielectric layer.

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