Stepped micro heater for phase change photonic device and preparation method of stepped micro heater

Abstract

The invention belongs to the field of photoelectrons, and particularly discloses a stepped micro heater for a phase change photonic device and a preparation method of the stepped micro heater. The micro heater comprises a substrate, a phase change material film and at least three layers of electrodes, except for the bottom layer electrode, the remaining electrodes are located on the two sides of the phase-change material film from bottom to top in an open stepped mode, a heating area is arranged on the bottom layer electrode, and the phase-change material film is arranged above the heating area; the wide stepped structure of the electrode is used for optimizing current distribution on the electrode when a driving signal is applied to the top electrode, so that the current density of a heating area reaches a peak value, Joule heat is generated in the heating area in a concentrated mode, and then the state change of the phase change material film is achieved. The stepped micro heater of the phase change photonic device has the advantages of being high in heating efficiency, small in heat loss and high in switching speed.

Description

Technical Field

[0001] The present application belongs to the field of optoelectronics, and more specifically, to a stepped microheater for a phase change photonic device and a preparation method thereof. Background Art

[0002] In recent decades, with the rapid development of information technology, global communication data is growing at an exponential rate, which has put forward higher requirements for information processing chips in the fields of communication, storage and quantum computing. The contradiction between the explosive growth of information weight and the limited available physical resources (such as energy, space and channels) faced by the current information network has become the main contradiction in the information field. Photonic devices can be mass-produced at low cost without the need for expensive equipment. They can not only achieve low power consumption and greatly improve the working speed, but also realize the hybrid integration of photons and electrons on the same chip. In the long run, photonic devices based on phase change materials have unlimited potential and are expected to become a feasible way to break through the traditional development bottleneck. At the same time, they also put forward higher requirements on the power consumption, reliability and multi-functional integration of the new generation of photonic devices.

[0003] For photonic devices based on phase change materials, in which the state of the phase change material is affected by temperatures of different magnitudes, it is necessary to study a heater structure of the phase change photonic device with high heating efficiency and low heat loss. Summary of the invention

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a stepped microheater for phase change photonic devices and a preparation method thereof, aiming to solve the problems of low heating efficiency, high heat loss and slow switching speed of the heating electrode structure of traditional phase change photonic devices.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a stepped micro-heater for a phase-change photonic device, comprising: a substrate, a phase-change material film, and at least three layers of electrodes; all electrodes are arranged adjacent to each other from bottom to top, and a bottom electrode is arranged above the substrate; except for the bottom electrode, the remaining electrodes are arranged on both sides of the phase-change material film in an open stepped manner from bottom to top, that is, the window of the upper electrode is larger; a heating area is arranged on the bottom electrode, and a phase-change material film is arranged above the heating area; The open stepped structure of the electrode is used to optimize the current distribution on the electrode when a driving signal is applied to the top electrode, so that the current density in the heating area reaches a peak value, so as to generate Joule heat in the heating area, thereby realizing the change of the state of the phase change material film. Further preferably, the stepped microheater for phase change photonic devices also includes a cladding, which covers other areas except the phase change material film and the needle piercing area of ​​the top electrode; the needle piercing area of ​​the top electrode is used for the probe to apply an electric pulse on the top electrode; the cladding is used to accelerate the heat exchange between the cladding area and the electrode after the electric pulse ends, so as to reduce the temperature of the phase change material film.

[0006] Further preferably, the thickness of the phase change material film is thinner than the thickness of the adjacent intermediate electrode.

[0007] Further preferably, the electrode is provided with three layers, including a bottom electrode, a top electrode and a second electrode, and the thicknesses thereof are the same, and the thickness ranges from 10 nm to 1000 nm.

[0008] More preferably, the cladding is SiO 2 , its thickness is 0.1um~1000um.

[0009] Further preferably, the acupuncture area is rectangular and the heating area is rectangular.

[0010] Further preferably, the phase change material thin film material includes Sb 2 Se 3 Or Ge 2 Sb 2 Te 5 ; Further preferably, the electrode material includes W, In 2 O 3 , Pt, ITO, Au or Ag.

[0011] In a second aspect, based on the above-mentioned stepped microheater for phase change photonic devices, the present application provides a method for preparing a corresponding stepped microheater, comprising the following steps: Step S1: preparing a bottom electrode on a substrate; Step S2: preparing a step-type remaining electrode on the bottom electrode; Step S3: preparing a phase change material film at the heating area of ​​the bottom electrode.

[0012] Further preferably, step S1, step S2 and step S3 respectively prepare the bottom electrode, the remaining electrode and the phase change material film by any one of magnetron sputtering, evaporation, chemical vapor deposition, plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, metal compound vapor deposition, molecular beam epitaxy, atomic vapor deposition, atomic layer deposition and electron beam grazing angle deposition.

[0013] Further preferably, after step 3, the following steps are also included: covering the structure in step S3 with silicon oxide, and then digging holes based on dry etching to obtain a cladding pattern.

[0014] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: The present application provides a stepped microheater for a phase-change photonic device, comprising a substrate, a bottom electrode, an intermediate electrode, a top electrode, a phase-change material film and a cladding layer arranged on the bottom electrode; by applying a pulse voltage to the top electrode, a large amount of Joule heat is generated in the heating area, thereby realizing a rapid change in the state of the phase-change material. Compared with the conventional stepped microheater for phase-change photonic devices, the stepped microheater for phase-change photonic devices provided by the present application has the characteristics of high heating efficiency, small heat loss and fast switching speed.

[0015] The present application optimizes the structure, size and thickness of the heating area by regulating the shape, size and thickness of the electrode, so that the heating electrode material film has a suitable resistance, the temperature distribution in the heating area is uniform, the heating efficiency is high, and the preparation of the heating electrode material film is easy, the process steps are few and the fault tolerance is high, which can ensure the yield of the microheater.

[0016] In this application, the cladding has three holes: two in the needle puncture area and one in the phase change material; the two holes in the needle puncture area are used for the probe to apply electric pulses; the holes in the phase change material film can reduce heat loss, because the thermal conductivity of air is lower than that of the cladding material, and the heat exchange is slow, which can reduce heat loss. In contrast, the heat exchange between the cladding area without holes and the electrode is relatively rapid, resulting in a rapid drop in the electrode temperature after the electric pulse ends, which in turn causes a corresponding drop in the temperature of the phase change film material. This application effectively optimizes thermal management, improves the temperature control performance of the equipment, and meets the needs of rapid heating and cooling of phase change materials.

[0017] This application adopts a heating method with a stepped structure. By optimizing the current distribution, the current density in the heating area reaches a peak value, forming a local concentration in the heating area, so that the Joule heat is concentrated in the heating area; at the same time, the phase change material is directly set on the bottom electrode and directly in contact with the middle electrodes on both sides, which increases the heat conduction area, optimizes the heat transfer path, and significantly improves the heat conduction efficiency. Through the synergistic effect of heat source concentration and expansion of the heated area, a significant improvement in heating efficiency is achieved. This heating method not only improves energy utilization, but also ensures the uniformity and controllability of the heating process.

[0018] The preparation process of the heating electrode structure of the phase change photonic device provided in the present application is simple and has high fault tolerance, is compatible with traditional CMOS processes, is easy to integrate and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a schematic diagram of the electrode structure of a microheater of a phase change photonic device prepared according to an embodiment of the present application; Figure 2 is a pulse parameter diagram of a stepped microheater electrode applied to a phase change photonic device provided in an embodiment of the present application; Figure 3 This is a temperature distribution diagram of the stepped microheater of the phase change photonic device provided in an embodiment of the present application after a pulse is applied; Figure 4 It is a surface temperature curve diagram of a phase change material film after a pulse is applied to a stepped micro-heater of a phase change photonic device provided in an embodiment of the present application, and a comparison with other different structures; Figure 5 It is a process of applying pulses to a stepped microheater of a phase change photonic device provided in an embodiment of the present application, and a crystal phase transition curve diagram of a phase change material; Figure 6 It is a temperature curve diagram of the x-direction coordinate of the surface of the phase change material film after a pulse is applied to the stepped micro-heater of the phase change photonic device provided in an embodiment of the present application; Figure 7 It is a y-direction coordinate temperature curve diagram of the surface of the phase change material film after a pulse is applied to the stepped microheater of the phase change photonic device provided in an embodiment of the present application; Figure 8 It is a current density distribution curve diagram of the electrode after a pulse is applied to the stepped micro-heater of the phase change photonic device provided in an embodiment of the present application; Fig. 9 This is a temperature curve of different electrode sizes when the bridge side length of the phase change photonic device provided in an embodiment of the present application is 10 um; Fig.10 This is a temperature distribution comparison diagram of a phase change photonic device with and without cladding holes provided in an embodiment of the present application; Fig.11 is a process flow chart of a stepped heater for a phase change photonic device provided in an embodiment of the present application; In all the drawings, the same reference numerals are used to represent the same elements or structures, wherein: 101 is a substrate; 102 is a bottom electrode; 103 is an intermediate electrode; 104 is a top electrode; 105 is a phase change material film; 106 is a cladding; 107 is a heating area; and 108 is a needle puncture area. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] The term "and / or" in this article is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this article indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0022] The terms “first”, “second” and the like in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects.

[0023] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0024] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0025] In order to solve the problems of low heating efficiency and high heat loss of the heating electrode structure of traditional phase change photonic devices, the present application provides a stepped microheater of a phase change photonic device, including a substrate 101, a bottom electrode 102, an intermediate electrode 103, a top electrode 104 and a phase change material film 105 arranged on the bottom electrode 102; the area where the bottom electrode 102 located at the bridge is located is a heating area 107, and a needle pricking area 108 is arranged on the top electrode 104; the phase change material film 105 is placed on the bottom electrode 102; by applying a pulse voltage to the top electrode, Joule heat is generated in the heating area, thereby realizing a rapid change in the state of the phase change material; wherein, the intermediate electrode 103 can be a multi-layer electrode or a single-layer electrode.

[0026] In some embodiments, the shape of the acupuncture area 108 is rectangular rather than fish-mouth shaped; In some embodiments, the heating area 107 is rectangular in shape and has a certain size difference with the acupuncture area 108; the side length of the heating area 107 is 10 um; the side length of the acupuncture area 108 is 150 um; In some embodiments, the middle electrode 103 is a layer of electrode, namely, a second layer electrode; the thickness of the bottom electrode 102, the second layer electrode 103, and the top layer electrode 104 are all 100 nm, and the height difference of each step is 100 nm; In some embodiments, the substrate is made of silicon. The substrate is not particularly limited in the present application, and those skilled in the art may set it according to actual needs, which is within the protection scope of the present application.

[0027] It should be noted that, although the present application does not limit the size of the electrode, the size of the electrode must be within a suitable range and cannot be too small; those skilled in the art can prepare electrodes of appropriate size according to the actual situation such as the size of the probe for applying the pulsed electric wave. In some embodiments of the present application, the pattern of the above-mentioned electrode is a rectangle; In some embodiments, the phase change material film 104 is made of Sb 2 Se 3 Or Ge 2 Sb 2 Te 5 ; In some embodiments, the bottom electrode 102, the middle electrode 103, and the top electrode 104 are made of W, In 2 O 3 , Pt, ITO, Au or Ag materials; In some embodiments, the micro heater further includes a cladding layer 105 covering the middle electrode 103 and the top electrode 104; In some embodiments, the cladding layer is SiO 2 ; In some embodiments, the thickness of the cladding is 0.1um~1000um.

[0028] The present application also provides a method for preparing a stepped microheater of a phase change photonic device, comprising the following steps: A bottom electrode 102 is prepared on a substrate 101; The intermediate electrode 103 is prepared on the bottom electrode 102; A top electrode 104 is prepared on the middle electrode 103; A phase change material film 105 is formed at a heating region 107 of the bottom electrode 102; The coating layer 106 is prepared by applying glue on the photolithography phase change material film area and the electrode.

[0029] In some embodiments, the substrate 101, the bottom electrode 102, the middle electrode 103, the top electrode 104, the phase change material film 105 disposed at the bottom electrode 102 and the cladding 106 can be formed by any one of magnetron sputtering, evaporation, chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), metal compound vapor deposition (MOCVD), molecular beam epitaxy (MBE), atomic vapor deposition (AVD), atomic layer deposition (ALD) and electron beam grazing angle deposition (GLAD).

[0030] The preparation method provided in the present application does not include a series of steps of photolithography patterning. In actual implementation, the patterns corresponding to each device and the implementation methods of the photolithography steps can be designed according to requirements.

[0031] The above technical scheme is described in detail below in conjunction with specific embodiments. It should be understood that these are merely exemplary and are not intended to limit the present application. Materials that are the same or similar in type, model, quality, nature or function as the following materials and instruments can be used to implement the present application. The experimental methods used in the following embodiments and comparative examples are conventional methods unless otherwise specified. The materials used in the following embodiments and comparative examples, etc., can be obtained from commercial sources unless otherwise specified.

[0032] The following are examples and comparative examples: Example 1 like Figure 1 As shown, the embodiment of the present application provides a heating electrode of a phase change photonic device, including: a substrate 101, a bottom electrode 102, an intermediate electrode 103, a top electrode 104, a phase change material film 105 and a cladding 106 arranged at the bottom electrode 102; in this embodiment, the intermediate electrode is a layer electrode, that is, a second layer electrode; In this embodiment, the thickness of the substrate 101 is 550 , the thickness of the cladding 105 is 1 ; In this embodiment, the size of the heating area 107 is The two acupuncture areas 108 are sized The size of the phase change material film 105 is ; In this embodiment, the phase change material film 105 is made of Ge 2 Sb 2 Te 5 Material, thickness is 20nm; In this embodiment, the bottom electrode 102, the second electrode 103 and the top electrode 104 are all made of W material; It should be understood that the materials and thicknesses selected in this embodiment are only applicable to this embodiment and do not limit the content of this application; The following is a description of the method for preparing the heating electrode structure provided in the embodiment of the present application: (1) Spin-coat photoresist on a silicon substrate, bake for 2 minutes, use a maskless photolithography machine to photolithography the electrode pattern, then develop it in a developer, then use a magnetron sputtering coating machine to grow 100nm of electrode material W on the surface of the substrate, and then go through a degumming and stripping process to obtain the bottom electrode pattern; then transfer the developed pattern to the wafer by dry etching to obtain the bottom electrode; (2) After the electrode is grown, spin-coat the photoresist on the substrate, bake for 2 minutes, use a maskless photolithography machine to photolithography the pattern of the electrode bridge area, then develop it in a developer, and then use a magnetron sputtering coating machine to grow 100nm of electrode material W on the surface of the bottom electrode; finally, after the degumming and peeling process, the second layer of electrode and the heating area are obtained; (3) On the structure obtained in step (2), the photoresist is rotated and baked for 2 minutes. The pattern of the heating area is photolithographically processed using a maskless photolithography machine, and then developed in a developer. Then, a magnetron sputtering coating machine is used to grow electrode material W 100nm on the surface of the second electrode layer. Finally, after the degumming and stripping processes, the top electrode and the needle insertion area are obtained. (4) Spin-coat the photoresist on the structure obtained in step (3), bake for 2 minutes, use a maskless photolithography machine to photolithography the pattern of the phase change material film, then develop it in a developer, and then use a magnetron sputtering coating machine to grow the phase change material Ge on the surface of the bottom electrode. 2 Sb 2 Te 5 20nm; finally, after the debonding and stripping process, the phase change material film area is obtained; (5) Cover the structure obtained in step (4) with a silicon oxide cladding layer, photolithograph a hole pattern, and use an ICP etcher to dig the hole pattern after development to obtain a complete micro-heating electrode for the phase change photonic device.

[0033] Fig.11 It is a process flow chart of stepped microheater for phase change photonic devices.

[0034] It should be noted that the above description of the preparation process and structural parameters of the micro-heater structure is only an optional implementation method and should not be understood as the only limitation of the present application; The performance of the micro heater provided in the embodiment of the present application was tested. Figure 2 The pulse width shown is 0.6 The temperature distribution of the stepped microheater of the phase change photonic device is shown in the figure below: Figure 3 As shown, it can be seen that the temperature is concentrated in the heating area, and the phase change material film is heated evenly, which shows that the microheater prepared in this application has the characteristics of high heating efficiency, small heat loss and fast switching speed; Figure 4 The surface temperature curve of the phase change material film in the stepped microheater of the phase change photonic device is shown in Figure 1. Compared with other structures, the peak temperature reaches 1600°C, which is higher than other structures, and the switching speed is also the fastest. Figure 5 The graph showing the crystallization ratio of the phase change material changing with time shows that the phase change material has undergone a state change; Fig. 9The side length of the bridge for the phase change photonic device is 10 When the temperature curves of different electrode sizes are taken, it can be seen that the electrode should not be too small, which will affect the heating efficiency; Fig.10 This is a comparison chart of the temperature distribution of the phase change photonic device with and without holes in the cladding. It can be seen that the maximum temperature reached by digging holes is higher than that without holes, and the heat is more concentrated in the phase change material film area.

[0035] In summary, compared with the prior art, the present application has the following advantages: The present application provides a stepped microheater for a phase-change photonic device, comprising a substrate, a bottom electrode, an intermediate electrode, a top electrode, a phase-change material film and a cladding layer arranged on the bottom electrode; by applying a pulse voltage to the top electrode, a large amount of Joule heat is generated in the heating area, thereby realizing a rapid change in the state of the phase-change material. Compared with the conventional stepped microheater for phase-change photonic devices, the stepped microheater for phase-change photonic devices provided by the present application has the characteristics of high heating efficiency, small heat loss and fast switching speed.

[0036] The present application optimizes the structure, size and thickness of the heating area by regulating the shape, size and thickness of the electrode, so that the heating electrode material film has a suitable resistance, the temperature distribution in the heating area is uniform, the heating efficiency is high, and the preparation of the heating electrode material film is easy, the process steps are few and the fault tolerance is high, which can ensure the yield of the microheater.

[0037] In this application, the cladding has three holes: two in the needle puncture area and one in the phase change material; the two holes in the needle puncture area are used for the probe to apply electric pulses; the holes in the phase change material film can reduce heat loss, because the thermal conductivity of air is lower than that of the cladding material, and the heat exchange is slow, which can reduce heat loss. In contrast, the heat exchange between the cladding area without holes and the electrode is relatively rapid, resulting in a rapid drop in the electrode temperature after the electric pulse ends, which in turn causes a corresponding drop in the temperature of the phase change film material. This application effectively optimizes thermal management, improves the temperature control performance of the equipment, and meets the needs of rapid heating and cooling of phase change materials.

[0038] This application adopts a heating method with a stepped structure. By optimizing the current distribution, the current density in the heating area reaches a peak value, forming a local concentration in the heating area, so that the Joule heat is concentrated in the heating area; at the same time, the phase change material is directly set on the bottom electrode and directly in contact with the middle electrodes on both sides, which increases the heat conduction area, optimizes the heat transfer path, and significantly improves the heat conduction efficiency. Through the synergistic effect of heat source concentration and expansion of the heated area, a significant improvement in heating efficiency is achieved. This heating method not only improves energy utilization, but also ensures the uniformity and controllability of the heating process.

[0039] The preparation process of the heating electrode structure of the phase change photonic device provided in the present application is simple and has high fault tolerance, is compatible with traditional CMOS processes, is easy to integrate and is suitable for large-scale production.

[0040] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0041] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0042] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. Among them, "fixed connection" means that the relative position relationship after connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0043] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0044] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A stepped microheater for a phase change photonic device, characterized in that: include: A substrate, a phase change material film and at least three layers of electrodes; all electrodes are arranged adjacent to each other from bottom to top, and a bottom electrode is arranged above the substrate; except for the bottom electrode, the remaining electrodes are arranged on both sides of the phase change material film in an open step-type from bottom to top; a heating area is arranged on the bottom electrode, and a phase change material film is arranged above the heating area; The open stepped structure of the electrode is used to optimize the current distribution on the electrode when a driving signal is applied to the top electrode, so that the current density in the heating area reaches a peak value, so as to generate Joule heat in the heating area, thereby realizing the change of the state of the phase change material film.

2. The stepped micro heater according to claim 1, characterized in that: It also includes a cladding layer, which covers other areas of the processed phase change material film and the needle piercing area of ​​the top electrode; the needle piercing area of ​​the top electrode is used for the probe to apply an electric pulse on the top electrode; the cladding layer is used to accelerate the heat exchange between the cladding area and the electrode after the electric pulse ends, so as to reduce the temperature of the phase change material film.

3. The stepped micro heater according to claim 1 or 2, characterized in that: The thickness of the phase change material film is lower than the thickness of the adjacent intermediate electrode.

4. The stepped micro-heater according to any one of claims 1 to 3, characterized in that: The electrode is provided with three layers, including a bottom electrode, a top electrode and a second electrode, and the thickness thereof is the same, and the thickness ranges from 10nm to 1000nm.

5. The stepped micro heater according to claim 2, characterized in that: The cladding is SiO2, and its thickness is 0.1um~1000um.

6. The stepped micro-heater according to claim 2 or 5, characterized in that: The acupuncture area is rectangular and the heating area is rectangular.

7. The stepped micro heater according to claim 1, characterized in that: The phase change material thin film material includes Sb2Se3 or Ge2Sb2Te5; the electrode material includes W, In2O3, Pt, ITO, Au or Ag.

8. A method for preparing a stepped micro-heater according to any one of claims 1 to 7, characterized in that: The following steps are involved: Step S1: preparing a bottom electrode on a substrate; Step S2: preparing a step-type remaining electrode on the bottom electrode; Step S3: preparing a phase change material film at the heating area of ​​the bottom electrode.

9. The preparation method according to claim 8, characterized in that: Step S1, step S2 and step S3 respectively prepare the bottom electrode, the remaining electrode and the phase change material film by any one of magnetron sputtering, evaporation, chemical vapor deposition, plasma enhanced chemical vapor deposition, low pressure chemical vapor deposition, metal compound vapor deposition, molecular beam epitaxy, atomic vapor deposition, atomic layer deposition and electron beam grazing angle deposition.

10. The preparation method according to claim 8, characterized in that: The step S3 also includes the following steps: covering the structure in step S3 with silicon oxide, and then digging holes based on dry etching to obtain a cladding pattern.

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