Three-dimensional spiral variable thin-film inductor and method of manufacture

Abstract

The application belongs to the technical field of thin film inductance and magnetron sputtering, and particularly relates to a three-dimensional spiral variable thin film inductance and a preparation method thereof. The inductance comprises a racetrack type magnetic core, the magnetic core comprises oppositely arranged first and second long arms, oppositely arranged first and second short arms, a plurality of first spiral coils arranged on the first long arm, and a plurality of second spiral coils arranged on the second long arm. Each first spiral coil is provided with contacts at both ends, adjacent first spiral coils are connected in series through shared contacts located between the two, each second spiral coil is provided with contacts at both ends, and adjacent second spiral coils are connected in series through shared contacts located between the two. The magnetic core is a high-entropy alloy magnetic core, and the high-entropy alloy composition comprises Zr and / or B, Fe, Co and Ni. The application can supply power to each coil individually or to the combination of multiple coils through the contacts, and has stronger design and application flexibility.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of thin film inductance and magnetron sputtering, and particularly relates to a three-dimensional spiral variable thin film inductance and a preparation method. BACKGROUND

[0002] In recent years, due to the driving of the product market, an important development trend of power electronics technology is system miniaturization and system functionalization. Miniaturization of portable devices from the portable electronic product market also requires miniaturization of power management circuits (such as DC-DC converters). Discrete passive components, i.e. inductors and transformers, are usually the largest components in power systems. Miniaturized inductors can achieve a higher degree of system integration to realize power system on chip (PwrSoC). Thin film inductors use a new inductor manufacturing technology as a thin film technology, combined with the application of high-performance magnetic materials, to meet the requirements.

[0003] At present, due to the complexity of application and the diversity of demand scenarios, the thin film inductors of major manufacturers all have numerous product models to meet the needs of different application scenarios, which undoubtedly increases the complexity of product variety quantity, resulting in high research and development, design and manufacturing costs. Therefore, it is of great significance to design a performance controllable thin film inductance structure, expand the application scenarios of thin film inductors, and reduce development and manufacturing costs. SUMMARY

[0004] The application aims to overcome the shortcomings of the prior art, and provides a three-dimensional spiral variable thin film inductance suitable for multiple power requirements and a preparation method. The application proposes a thin film inductance structure, which adopts a racetrack-shaped magnetic core and sets 4 spiral coils on both sides of the racetrack. All the spiral coils have the same design, the same number of turns and the same cross-sectional area. The 4 spiral coils on the same side are connected in series with each other and each has 5 contact points, which can be flexibly contacted with the equipment. This structure has stronger flexibility, which can not only supply power to each spiral coil individually, but also combine with each other to realize mutual modulation of inductance. This design can be used for devices with more power designs, while reducing the variety of types and reducing costs.

[0005] The complete technical solution of the application includes:

[0006] A three-dimensional spiral variable thin film inductor includes a racetrack-shaped magnetic core, the racetrack-shaped magnetic core includes a first long arm and a second long arm arranged opposite to each other, a first short arm and a second short arm arranged opposite to each other, a plurality of first spiral coils arranged on the first long arm, and a plurality of second spiral coils arranged on the second long arm; each first spiral coil is provided with contacts at both ends, adjacent first spiral coils are connected in series through a shared contact located between the two, each second spiral coil is provided with contacts at both ends, and adjacent second spiral coils are connected in series through a shared contact located between the two.

[0007] The racetrack-shaped magnetic core is a high-entropy alloy magnetic core, and the high-entropy alloy includes Fe, Co, Ni, and Zr and / or B elements.

[0008] Further, the number of the first spiral coils and the second spiral coils is the same.

[0009] Further, the first spiral coils and the second spiral coils have the same number of turns.

[0010] Further, the first spiral coils and the second spiral coils have the same cross-sectional area.

[0011] Further, each spiral coil can be powered individually or a combination of multiple spiral coils can be powered through the contacts.

[0012] Further, the number of the first spiral coils and the second spiral coils is 4, and the number of contacts on the first spiral coils and the second spiral coils is 5.

[0013] Further, the composition and content range of the high-entropy alloy are as follows:

[0014] 1) composed of Zr, Fe, Co, and Ni, and the content range of each element is: Zr: 10.5-14.2 at%, Fe: 21.7-50.5 at%, Co: 16.4-53.4 at%, and Ni: 12.3-22.1 at%; or

[0015] 2) composed of B, Fe, Co, and Ni, and the content range of each element is: B: 7.5-12.1 at%, Fe: 20.3-54.5 at%, Co: 13.5-58.5 at%, and Ni: 11.2-22.5 at%; or

[0016] 3) composed of B, Zr, Fe, Co, and Ni, and the content range of each element is: B: 4.6-8.8 at%, Zr: 2.7-6.5 at%, Fe: 20.3-54.5 at%, Co: 13.5-58.5 at%, and Ni: 11.2-22.5 at%.

[0017] Further, the optimized component content of the high-entropy alloy is determined by a high-throughput screening component design method.

[0018] Further, by switching the contacts of the three-dimensional spiral variable thin-film inductor, different taps are selected to adjust the effective number of turns of the inductor, thereby controlling the inductance value, and realizing multi-inductance demand applications.

[0019] Further, the preparation method of the three-dimensional spiral variable thin-film inductor comprises the following steps:

[0020] Step (1) sputter a SiO2 layer on a substrate, and after photoetching a lower coil pattern, magnetron sputter a lower seed layer, and electroplate a lower copper coil on the lower seed layer;

[0021] Step (2) then photoetch a lower copper column via hole pattern and electroplate a lower copper column, remove photoresist and etch to remove the seed layer: obtain a lower copper wire layer and a copper column;

[0022] Step (3) spin PI layer to completely cover the copper column, and polish the surface of the PI layer to expose the surface of the copper column;

[0023] Step (4) photoetch a high-entropy alloy magnetic core pattern, and obtain a high-entropy alloy magnetic core layer by magnetron sputtering;

[0024] Step (5) prepare an upper copper column via hole pattern and electroplate an upper copper column in the same way as step (2);

[0025] Step (6) prepare an upper copper coil and a contact PAD in the same way as step (1);

[0026] Step (7) etch to remove the upper seed layer to obtain a three-dimensional spiral variable thin-film inductor.

[0027] Compared with the prior art, the beneficial effects of the present application are:

[0028] (1) stronger design and application flexibility: this structure can be flexibly adjusted according to different demand scenarios, and can realize design requirements in various scenarios; at the same time, the inductor device of this structure has stronger application flexibility, can supply power to each coil separately, or can be combined with each other to realize mutual modulation of inductance. This design can be used for more power design devices, reducing the variety of types and reducing the research and development and manufacturing costs.

[0029] (2) the spiral structure can obtain larger inductance: compared with a simple planar spiral inductor, the coils are located in the same plane, and due to the limited space, the number of coils is relatively limited, and the inductance value is relatively limited. In comparison, the three-dimensional spiral inductor increases the number of coils, which is more conducive to obtaining a larger inductance value and improving the overall performance of the inductor.

[0030] (3) Compatible with semiconductor process, suitable for batch industrial production: the manufacturing process adopts thin film technology and semiconductor process, good compatibility, various application scenarios, high adjustability, suitable for batch production. BRIEF DESCRIPTION OF DRAWINGS

[0031] Fig. 1 It is a plan view of the three-dimensional spiral variable thin film inductor of the application.

[0032] Fig. 2 It is a perspective view of the three-dimensional spiral variable thin film inductor of the application.

[0033] Fig. 3 It is a schematic view of the spiral coil.

[0034] In the figure, 1 is a magnetic core, 2 is a first spiral coil, 3 is a second spiral coil, 4 is a first contact, and 5 is a second contact. DETAILED DESCRIPTION

[0035] The application will be described in detail below in conjunction with the embodiments and drawings, but it should be understood that the embodiments and drawings are only used to exemplarily describe the application and cannot constitute any limitation on the protection scope of the application. All reasonable transformations and combinations within the inventive concept of the application fall within the protection scope of the application.

[0036] As Figs. 1-3 shown, the application discloses a three-dimensional spiral variable thin film inductor suitable for multiple power requirements, which comprises a runway-type magnetic core 1, the magnetic core comprises a first long arm and a second long arm arranged opposite to each other, a first short arm and a second short arm arranged opposite to each other, a plurality of first spiral coils 2 arranged on the first long arm, and a plurality of second spiral coils 3 arranged on the second long arm; the number of the first spiral coils and the second spiral coils is the same, the first spiral coils and the second spiral coils have the same number of turns and cross-sectional area, each first spiral coil is provided with a first contact 4 at both ends, adjacent first spiral coils are connected in series through a shared first contact located between the two, each first spiral coil is provided with a second contact 5 at both ends, and adjacent second spiral coils are connected in series through a shared second contact located between the two; preferably, the number of the first spiral coils and the second spiral coils is 4, and the number of the contacts on the first spiral coils and the second spiral coils is 5.

[0037] The three-dimensional spiral variable thin film inductor of the application can supply power to each spiral coil individually or supply power to multiple spiral coils in combination through the contacts. Specifically,

[0038] Inductance calculation formula:

[0039]

[0040] wherein, L is inductance [H], K is Nagata coefficient, p is permeability, N is the number of turns, S is the cross-sectional area of the coil [m 2 ], is the length of the coil [m].

[0041] Since the inductance L is proportional to the square of the number of turns N (L∝N 2 ), by switching the contact of the variable thin-film inductor of the three-dimensional spiral to select different taps, the effective number of turns of the inductor can be adjusted, so as to accurately control the inductance value, so as to realize the multi-inductance demand application. For example, if the total number of turns is 100, the contact is connected to the 80th turn, and the inductance is about 64% of the total number of turns.

[0042] Inductance L is proportional to the square of the permeability of the racetrack-shaped magnetic core (L∝ ), and the good soft magnetic performance of the magnetic core is conducive to the improvement of the inductance performance. The high-entropy alloy magnetic core used in the application has good soft magnetic performance and high resistivity characteristics. The high resistivity characteristics are conducive to reducing eddy current loss, reducing the total loss of the device to reduce the heat generation, and ensuring the stability of the device.

[0043] In the application, the optimal composition of the high-entropy alloy used in the racetrack-shaped magnetic core is determined by a high-throughput screening composition design method. In order to illustrate the alloy composition optimization process of the application, the high-throughput screening method used is further described.

[0044] (1.1) Multicomponent gradient thin film sputtering: using a magnetron sputtering process, controlling the chamber atmosphere conditions, depositing each component element of the high-entropy alloy target material on each substrate surface by magnetron sputtering, and obtaining a plurality of thin film samples with different component contents.

[0045] Firstly, the content of each component element determined by the application is in the preset range:

[0046] 1) Zr: 10.5~14.2 at%, Fe: 21.7~50.5 at%, Co: 16.4~53.4 at%, Ni: 12.3~22.1 at%; or

[0047] 2) B: 7.5~12.1 at%, Fe: 20.3~54.5 at%, Co: 13.5~58.5 at%, Ni: 11.2~22.5 at%; or

[0048] 3) B: 4.6~8.8 at%, Zr: 2.7~6.5 at%, Fe: 20.3~54.5 at%, Co: 13.5~58.5 at%, Ni: 11.2~22.5 at%;

[0049] In the process, in order to make the composition content of the thin film sample in the preset range, and the content of each component in each sample is as uniform as possible, which is beneficial to subsequent high-throughput screening. Due to the different atomic binding forces of each target material in the sputtering process, the atomic detachment speed of each target material is different. The present application analyzes the law of the spatial distribution of the atomic detachment of each target material (the concentration of target element atoms in space gradually decreases with the increase of the distance from the target material), analyzes the main influencing factors (the total number of samples, the horizontal and vertical spacing of each sample), and selects the following experimental method:

[0050] High-purity Fe, high-purity Co, high-purity Ni, and high-purity M target materials are used, and are uniformly placed in four positions in the chamber, wherein the M target material is a Zr target material, or a B target material, or a mixed target material of Zr and B. The angles of the four target positions are adjusted to be 45° with the horizontal angle, the sample holder is placed in the middle of the four target materials, and a plurality of high-resistivity non-magnetic material substrates are placed on the sample holder.

[0051] First, a fixed sputtering time t0 and the same sample at a fixed distance d0 from the target material are selected, and the deposition thickness of each target element on the sample surface at different powers is measured to represent the detachment speed at different powers. Subsequently, taking Fe component as the reference, the reference sputtering power (250W) of Fe target material and the detachment speed of Fe at the power are determined, and then the corresponding power is selected for other components, so that the detachment speed at the corresponding sputtering power meets:

[0052]

[0053] In the formula: is the component the detachment speed at the selected corresponding power, is the detachment speed of the Fe component at the reference sputtering power, is the component the minimum atomic percentage content in the preset range, is the component the maximum atomic percentage content in the preset range, is the minimum atomic percentage content of Fe in the preset range, is the maximum atomic percentage content of Fe in the preset range.

[0054] When M is a Zr target or a B target, the maximum and minimum values of the atomic percentage of the M component are the maximum and minimum values of the atomic percentage of Zr and B elements respectively, and when M is a Zr / B mixed target, the maximum value of the atomic percentage of the M component is the sum of the maximum values of the atomic percentage of Zr and B elements, and the minimum value of the atomic percentage of the M component is the sum of the minimum values of the atomic percentage of Zr and B elements.

[0055] Subsequently, the placement parameters (horizontal spacing, vertical spacing and number) of the samples are determined. The Fe target and the M target are selected, and the deposition rate (the ratio of the deposition thickness of the substrate surface to the deposition time) of the sample closest to the Fe target and the deposition rate of the sample farthest from the Fe target are measured under the conditions of different sample spacing (horizontal spacing, vertical spacing) and sample number, and the degree of attenuation is counted. The relationship between the degree of attenuation and the sample horizontal spacing, vertical spacing and sample number is obtained by multiple linear regression, wherein when M is a Zr target and a B target, the deposition rates of Zr and B elements are counted and analyzed respectively, and when M is a Zr / B mixed target, the total deposition rate of the two elements is counted and analyzed.

[0056] According to the obtained relationship, the corresponding sample spacing and number are selected to satisfy:

[0057]

[0058]

[0059] In the formula, is the maximum value of the atomic percentage ratio of the Fe component to the M component in the preset range, is the maximum value of the atomic percentage ratio of the M component to the Fe component in the preset range in the high-throughput test. Similarly, when M is a Zr target and a B target, the maximum and minimum values of the atomic percentage of the M component are the maximum and minimum values of the atomic percentage of Zr and B elements respectively, and when M is a Zr / B mixed target, the maximum value of the atomic percentage of the M component is the sum of the maximum values of the atomic percentage of Zr and B elements, and the minimum value of the atomic percentage of the M component is the sum of the minimum values of the atomic percentage of Zr and B elements. is the deposition rate of Fe atoms on the sample closest to the Fe target, is the deposition rate of Fe atoms on the sample farthest from the Fe target; is the deposition rate of M atoms on the sample closest to the M target, is the deposition rate of M atoms on the sample farthest from the M target.

[0060] The finally selected parameters are: horizontal spacing 2.5 cm, vertical spacing 1.3 cm, and number 60.

[0061] (1.2) Sample testing and target material composition design: test the obtained multiple film samples, and screen the specific content of each element of the high-entropy alloy and the high-entropy alloy target material according to the performance requirements of saturation magnetization, coercivity and resistivity.

[0062] After the target material is prepared, the target material is cut and processed, and then heat treated, in terms of the target material cutting processing size and heat treatment process, a response surface model is constructed for experimental design, and the optimized parameter combination is obtained according to the experimental results, and the controllable variables selected include: target material cutting thickness X1, the value range is 10-20mm; target material cutting diameter X2, the value range is 100-150mm; heat treatment times X3, the value range is 1-3 times; heat treatment temperature X4, the value range is 700-1000℃; heat treatment time X5, the value range is 1-15 hours.

[0063] The degree of composition content deviation Y is selected as the response variable. Factor level coding is performed, the actual experimental parameters are constructed according to the coded values of the designed experiments, the designs that do not meet the actual requirements are removed, central composite experimental design is performed, multiple experiments are performed, the composition content deviation degree Y of each experiment is measured and calculated. A second-order polynomial regression model based on the composition content deviation degree and the controllable variable is established, the least square method is used to fit the coefficient estimates of the regression model, the predicted composition content deviation degree Y obtained by the regression model is taken as the objective function, and the objective is to minimize Y. Set the initial solution and perform iterative optimization, when the set maximum iteration number is reached, the current solution at this time is the optimized parameter combination. Specifically, the target material cutting diameter is 142mm, the cutting thickness is 16mm, the two-stage heat treatment process is adopted, wherein the first-stage heat treatment temperature is 820℃, the heat treatment holding time is 10h; the second-stage heat treatment temperature is 980℃, and the heat treatment holding time is 1.5h.

[0064] By using the above inert gas plus two-stage homogenization heat treatment method, the first-stage heat treatment temperature is lower than the second-stage heat treatment temperature, and the heat treatment time is longer, so that the good homogenization effect is ensured, and local overburning and abnormal grain growth caused by high temperature and long holding time are avoided.

[0065] The preparation method of the three-dimensional spiral variable thin film inductor of the application is as follows:

[0066] S1. Substrate preparation: a high-resistance silicon substrate is used, and a SiO2 layer with a thickness of about 1μm is sputtered to reduce substrate loss.

[0067] S2. Photolithography of lower copper coil: spin coating photoresist, baking, exposure and development, etc. to obtain the lower copper coil pattern.

[0068] S3. Seed layer sputtering: sputtering Ti / Cu seed layer to improve the adhesion of electroplated copper.

[0069] S4. Electroplating lower copper coil: electroplating copper layer on seed layer, electroplating current density is 20 mA / cm 2 , time is 10 min.

[0070] S5. Removing photoresist.

[0071] S6. Copper pillar via pattern photolithography: spin-coating photoresist, baking, exposure and development.

[0072] S7. Electroplating copper pillar.

[0073] S8. Removing photoresist and etching to remove Cu seed layer: obtaining lower copper wire layer and copper pillar.

[0074] S9. Thickly coating polyimide layer (PI) and polishing: spin-coating PI layer to completely cover copper pillar, polishing PI layer surface to expose clear copper pillar surface.

[0075] S10. High-entropy alloy magnetic core layer shape photolithography: spin-coating photoresist, baking, exposure and development, etc. to obtain high-entropy alloy magnetic core pattern.

[0076] S11. Magnetron sputtering high-entropy alloy magnetic core layer.

[0077] S12. Copper pillar via pattern photolithography and electroplating copper pillar, thickly coating PI layer and polishing: steps are same as S6, S7 and S8.

[0078] S13. Upper copper coil and contact PAD shape photolithography: spin-coating photoresist, baking, exposure and development, etc. to obtain upper copper coil and contact PAD shape pattern.

[0079] S14. Upper copper coil and contact PAD electroplating preparation and post-processing: steps are same as S3, S4, S5.

[0080] S15. Etching to remove seed layer to obtain three-dimensional spiral variable thin film inductor.

[0081] Other embodiments of the present disclosure will be readily apparent to those skilled in the art in view of the disclosure herein. The present disclosure is intended to cover any alternatives, modifications, and equivalents of the methods and applications described herein, which are in accordance with the spirit and scope of the disclosure. The specification and examples given herein are further intended to be illustrative only and not in a limiting sense. Thus, the true scope and spirit of the present disclosure should be indicated by the following claims.

Claims

1. A three-dimensional spiral variable thin-film inductor, characterized by, The runway type magnetic core comprises a first long arm and a second long arm arranged opposite to each other, a first short arm and a second short arm arranged opposite to each other, a plurality of first spiral coils arranged on the first long arm, and a plurality of second spiral coils arranged on the second long arm; each first spiral coil is provided with contacts at both ends, and adjacent first spiral coils are connected in series through a shared contact located between the two; each second spiral coil is provided with contacts at both ends, and adjacent second spiral coils are connected in series through a shared contact located between the two; By switching the contacts of the variable thin film inductor of the three-dimensional spiral, different taps are selected, the effective number of turns of the inductor is adjusted, the inductance value is controlled, and the application of multiple inductances is realized; The runway type magnetic core is a high-entropy alloy magnetic core, and the components of the high-entropy alloy include Fe, Co, Ni, and Zr and / or B elements; The content of each component of the high-entropy alloy is determined by a high-throughput screening component design method, including: Multi-component gradient thin film sputtering: using a magnetron sputtering process, controlling the chamber atmosphere conditions, depositing each component element of the high-entropy alloy target material on the surface of each substrate to obtain a plurality of thin film samples with different component contents; The content of each component element is in the following preset range: 1) Zr: 10.5-14.2 at%, Fe: 21.7-50.5 at%, Co: 16.4-53.4 at%, Ni: 12.3-22.1 at%; or 2) B: 7.5-12.1 at%, Fe: 20.3-54.5 at%, Co: 13.5-58.5 at%, Ni: 11.2-22.5 at%; or 3) B: 4.6-8.8 at%, Zr: 2.7-6.5 at%, Fe: 20.3-54.5 at%, Co: 13.5-58.5 at%, Ni: 11.2-22.5 at%; High-purity Fe, high-purity Co, high-purity Ni, and high-purity M target materials are uniformly placed at four positions in the chamber, wherein the M target material is a Zr target material, or a B target material, or a mixed Zr and B target material; Taking the Fe component as a reference, the reference sputtering power of the Fe target material and the desorption speed of Fe under the power are determined, and then corresponding powers are selected for other components so that the desorption speed under the corresponding sputtering power meets: In the formula: is the component is the desorption rate at the selected corresponding power, is the desorption rate of the Fe component at the reference sputtering power, is the component is the minimum atomic percentage content within the preset range of content, is the component is the maximum atomic percentage content within the preset range, is the minimum atomic percentage content of Fe within the preset range, is the maximum atomic percentage content of Fe within the preset range; when M is a Zr target or a B target, the maximum and minimum atomic percentage contents of the M component are the maximum and minimum atomic percentage contents of the Zr and B elements respectively; when M is a Zr / B mixed target, the maximum atomic percentage content of the M component is the sum of the maximum atomic percentage contents of the Zr and B elements, and the minimum atomic percentage content of the M component is the sum of the minimum atomic percentage contents of the Zr and B elements. Determine the placement parameters of the sample: horizontal distance, vertical distance, and number; select the Fe target material and the M target material, respectively, under different horizontal distances, vertical distances, and sample numbers, measure the deposition rate of the sample closest to it and the deposition rate of the sample farthest from it, and statistically analyze the degree of attenuation, and use multiple linear regression to obtain the relationship between the degree of attenuation and the sample horizontal distance, vertical distance, and sample number, wherein, when M is a Zr target material and a B target material, the deposition rates of Zr and B elements are respectively statistically analyzed and correspondingly analyzed, and when it is a Zr / B mixed target material, the total deposition rate of the two elements is statistically analyzed; according to the obtained relationship, the corresponding sample distance and number are selected so that: In the formula, is the maximum value of the atomic percentage ratio of the Fe component to the M component within a predetermined range, is the maximum value of the atomic percentage ratio of the M component to the Fe component within a predetermined range in high flux testing, when M is a Zr target and a B target, the maximum and minimum values of the atomic percentage of the M component are the maximum and minimum values of the atomic percentage of the Zr and B elements, when it is a Zr / B mixed target, the maximum value of the atomic percentage of the M component is the sum of the maximum values of the atomic percentage of the Zr and B elements, and the minimum value of the atomic percentage of the M component is the sum of the minimum values of the atomic percentage of the Zr and B elements; is the deposition rate of Fe atoms on the sample closest to the Fe target, is the deposition rate of Fe atoms on the sample farthest from the Fe target; is the deposition rate of M atoms on the sample closest to the M target, is the deposition rate of M atoms on the sample farthest from the M target; The obtained plurality of film samples are tested, and according to the performance requirements of saturation magnetization, coercivity and resistivity, the specific content of each component element of the high-entropy alloy is screened.

2. A three-dimensional spiral variable thin-film inductor as defined in claim 1, wherein, The first spiral coil and the second spiral coil have the same number.

3. A three-dimensional spiral variable thin-film inductor as defined in claim 2, wherein, The first spiral coil and the second spiral coil have the same number of turns.

4. A three-dimensional spiral variable thin-film inductor as claimed in claim 3, characterized in that, The first spiral coil and the second spiral coil have the same cross-sectional area.

5. A three-dimensional spiral variable thin-film inductor as claimed in claim 4, characterized in that, Each spiral coil can be powered individually or multiple spiral coils can be powered in combination through the contacts.

6. A three-dimensional spiral variable thin-film inductor as defined in claim 5, wherein, The first spiral coil and the second spiral coil each have 4 numbers, and the first spiral coil and the second spiral coil each have 5 numbers of contacts.

7. The method of claim 6 wherein the three-dimensional spiral variable thin film inductor is formed by the steps of: The method comprises the following steps: ​ Step (1) sputtering a SiO2 layer on a substrate, and after obtaining a lower coil pattern by photolithography, magnetron sputtering a lower seed layer, and electroplating a lower copper coil on the lower seed layer; Step (2) then, photolithography of the lower copper column via hole pattern and electroplating of the lower copper column, removal of photoresist and etching of the lower seed layer: obtaining a lower copper wire layer and a copper column; Step (3) spin coating a PI layer to completely cover the copper column, and polishing the surface of the PI layer to expose the surface of the copper column; Step (4) photolithography of the high-entropy alloy magnetic core pattern, and obtaining a high-entropy alloy magnetic core layer by magnetron sputtering; Step (5) preparing an upper copper column via hole pattern in the same way as step (2) and electroplating an upper copper column; Step (6) preparing an upper copper coil and a contact PAD in the same way as step (1); Step (7) etching to remove the upper seed layer to obtain a three-dimensional spiral variable thin film inductor.

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