A coreless arched MEMS inductor and a preparation method thereof

Abstract

The application discloses a coreless arched MEMS inductor and a preparation method thereof, and belongs to the technical field of semiconductors. The coreless arched MEMS inductor comprises a glass substrate, an inductor coil, a fuse pad and a non-photosensitive polyimide coating. The inductor coil comprises an inductor bottom coil and an inductor top arched coil. The fuse pad comprises a first fuse pad, a first connecting line of the first fuse pad, a second fuse pad and a second connecting line of the second fuse pad. The inductor bottom coil and the first fuse pad are electroplated on the glass substrate. The two ends of the inductor coil are connected with the first fuse pad and the second fuse pad respectively. The non-photosensitive polyimide coating is attached to the surface of the glass substrate and serves as a supporting layer of the inductor top arched coil. The inductor top arched coil and the non-photosensitive polyimide coating are in the same shape. The top surface of the fuse pad and the top surface of the inductor top arched coil are not covered by the non-photosensitive polyimide coating. The preparation time is shortened by 15% to 20% by using the application.

Description

TECHNICAL FIELD

[0001] The application relates to a coreless arched MEMS inductor and a preparation method, and belongs to the technical field of semiconductors. BACKGROUND

[0002] As one of important components in microelectronic devices, the coreless three-dimensional inductor is widely used in the fields of MEMS sensors, RF MEMS and micro energy storage devices. The inductor coil wound by enameled wire has a large volume, low production efficiency, and poor repeatability. The inherent defects of the traditional technology for winding the inductor coil cannot meet the existing requirements. The devices based on the inductor have an increasing demand for miniaturized inductors with small volume, high production efficiency and excellent performance. The micro-nano processing technology can realize the structure manufacturing and batch production of devices with micron or even nanometer level precision, thereby overcoming the shortcomings of the traditional inductor manufacturing technology. The micro-miniaturization and precision manufacturing of the inductor can be realized by using the MEMS (Micro-Electro-Mechanical Systems) process.

[0003] At present, the manufacturing of the three-dimensional MEMS inductor is mostly performed by using the UV-LIGA, TSV (Through-Silicon Vias) and DRIE (Deep Reactive Ion Etching) processes. The processes are as follows: first, a bottom coil is prepared; then, a high aspect ratio post is prepared through the processes of exposure, etching and electroplating; finally, a top coil is prepared. The three-dimensional inductor can be prepared by connecting the bottom coil and the top coil through the high aspect ratio post. The manufacturing of the high aspect ratio structure is difficult and has a high processing cost. The structure mask can be manufactured only by exposing and developing the specific thick photoresist for a long time. The post with a height of dozens or even hundreds of microns needs to be prepared through a long time of electroplating. The process flow is complicated and the manufacturing cost is high.

[0004] The photoresist hot reflow process is a process in which the developed photoresist is deformed under the condition that the heating temperature is higher than the glass transition temperature. After the heating treatment, the photoresist can be transformed from a rectangle into a sphere or a cylinder, so that the flatness of the photoresist is improved. The three-dimensional MEMS inductor can be combined into an arched or arched coil by the photoresist hot reflow process, so as to simplify the preparation process. Although the three-dimensional MEMS inductor prepared by using the photoresist hot reflow process does not need to prepare the high aspect ratio post, the photoresist as the support layer of the three-dimensional inductor is easily affected in the subsequent process. In addition, the stress generated in the process of removing the photoresist as the sacrificial layer by using the degreasing liquid such as acetone and NMP can reduce the mechanical stability of the inductor and even break the inductor.

[0005] In addition, the prior art uses a silicon wafer as a substrate of the coreless three-dimensional inductor, but the silicon wafer substrate increases the loss of the inductor and reduces the quality factor of the inductor. Therefore, how to prepare a coreless three-dimensional inductor with high quality and high stability by using a simple and easy-to-implement low-cost process has become a technical problem to be solved. SUMMARY

[0006] The present application provides a coreless arched MEMS inductor and a preparation method to solve the problems of complex processing, high preparation cost and poor stability of the prior art coreless three-dimensional MEMS inductor. By optimizing the structure of the coreless three-dimensional inductor, the mechanical stability of the inductor is improved, and the batch production of the micro inductor is completed.

[0007] The present application provides a coreless arched MEMS inductor, comprising: a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating.

[0008] The inductor coil comprises an inductor bottom coil and an inductor top arched coil, and the fuse pad comprises a first fuse pad and a first connecting line thereof, and a second fuse pad and a second connecting line thereof. The inductor bottom coil and the first fuse pad are electroplated on the glass substrate. The two ends of the inductor coil are connected through the first connecting line, the second connecting line, and the first fuse pad and the second fuse pad. The non-photosensitive polyimide coating is attached to the surface of the glass substrate as a support layer for the inductor top arched coil. The inductor top arched coil and the non-photosensitive polyimide coating are in the same shape. The top surface of the fuse pad and the top surface of the inductor top arched coil are not covered by the non-photosensitive polyimide coating.

[0009] Preferably, the two ends of the inductor bottom coil are connected through the first connecting line, the second connecting line, and the first fuse pad and the second fuse pad.

[0010] The present application also provides a preparation method of a coreless arched MEMS inductor, comprising the following steps:

[0011] Step S1: sequentially clean the glass substrate with acetone, isopropyl alcohol and deionized water, and blow dry;

[0012] Step S2: magnetron sputter a layer of Ti or Ti+Cu metal seed layer on the surface of the glass substrate;

[0013] Step S3: coat a layer of first positive photoresist on the surface of the Ti or Ti+Cu metal seed layer, and bake, expose and develop to obtain an inductor bottom coil groove, a first fuse pad groove, a first connecting line groove, a second fuse pad groove and a second connecting line groove;

[0014] Step S4, electroplating at the inductor bottom coil groove and the first and second fuse pad grooves to obtain the inductor bottom coil, the first and second fuse pads, the first and second connecting lines, and the two ends of the inductor bottom coil being connected through the first and second connecting lines and the first and second fuse pads respectively;

[0015] Step S5, removing the first positive photoresist using acetone to expose the Ti or Ti+Cu seed layer, and then removing the Ti or Ti+Cu seed layer using etching solution;

[0016] Step S6, spin-coating a layer of non-photosensitive polyimide coating and baking, and then coating a layer of second positive photoresist on the surface of the non-photosensitive polyimide coating and baking;

[0017] Step S7, through exposure and development, the support layer of the inductor top arch-shaped coil is shaped, and the fuse pads are wrapped in the non-photosensitive polyimide coating with the top of the fuse pads exposed outside;

[0018] Step S8, removing the residual second positive photoresist on the surface of the non-photosensitive polyimide coating using propylene glycol monomethyl ether acetate solution, and baking the non-photosensitive polyimide coating at high temperature in an oxygen-free environment to complete imidization;

[0019] Step S9, magnetron sputtering a layer of Cu metal seed layer on the surface of the non-photosensitive polyimide coating;

[0020] Step S10, coating a layer of third positive photoresist on the surface of the Cu metal seed layer and baking;

[0021] Step S11, through exposure and development, the inductor top arch-shaped coil groove is formed;

[0022] Step S12, electroplating at the inductor top arch-shaped coil groove to obtain the inductor top arch-shaped coil, so that the inductor top arch-shaped coil and the inductor bottom coil are closed to form a complete inductor coil 7 and realize electrical connection;

[0023] Step S13, removing the third positive photoresist using acetone, and then sequentially using isopropyl alcohol and deionized water to clean the surface to expose the Cu metal seed layer, and then removing the Cu metal seed layer using etching solution and slicing bonding to obtain the arch-shaped MEMS inductor without magnetic core.

[0024] Preferably, in step S2, the magnetron sputtering process parameters are as follows: the Ti sputtering power is 400W~600W, the Ti sputtering rate is 2.04Å / s~3.14Å / s, and the thickness is 500Å~1000Å; the Cu sputtering power is 300W~600W, the Cu sputtering rate is 3.68Å / s~6.59Å / s, and the thickness is 1000Å~2000Å.

[0025] Preferably, in step S3, the AZ positive photoresist is spin-coated or sprayed as the first positive photoresist, the thickness of the first positive photoresist is 5-15 μm, the baking temperature is 90-110 °C, the baking time is 200-350 s, the exposure mode is hard contact exposure, the exposure distance is 50-200 μm, the exposure dose is 230-600 mj, the developing solution is a basic solution of tetramethylammonium hydroxide or an organic solvent developing solution, and the developing time is 2 min 40 s-4 min.

[0026] In step S4, the electroplating solution is a Cu-ion-containing electroplating solution, the electroplating current is 0.182-0.251 A, and the electroplating time is 200-800 s.

[0027] In step S5, the acetone solution is soaked for 5-10 min, the etching solution is a Ti metal etching solution or a Ti metal etching solution and a Cu metal etching solution, the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid, and the Ti metal etching solution is an aqueous HF solution, wherein the mass percentage of HF in the aqueous solution is 2-8%.

[0028] Preferably, in step S6, the thickness of the non-photosensitive polyimide coating is 45-65 μm, the baking temperature is 110-140 °C, and the baking time is 200-300 s; the AZ positive photoresist is spin-coated or sprayed as the second positive photoresist, the thickness of the second positive photoresist is 5-15 μm, the baking temperature is 90-110 °C, and the baking time is 200-350 s.

[0029] Preferably, in step S7, the exposure mode is hard contact exposure, the exposure distance is 50-200 μm, the exposure dose is 230-600 mj, the developing solution is a basic solution of tetramethylammonium hydroxide or an organic solvent developing solution, and the developing time is 3 min 20 s-4 min 40 s.

[0030] Preferably, in step S8, the concentration of the propylene glycol monomethyl ether acetate solution is 99.1-99.9%, and the soaking time is 2 min 40 s-5 min 30 s; the baking temperature is 140-300 °C, and the baking time is 6-9 h.

[0031] Preferably, in step S9, the Cu sputtering power is 300-600 W, the Cu sputtering rate is 3.68-6.59 Å / s, and the thickness is 500-1000 Å.

[0032] In step S10, the AZ system positive photoresist is spin-coated or sprayed as the third positive photoresist, the thickness of the third positive photoresist is 5-15 microns, the baking temperature is 90-110 DEG C, and the baking time is 200-350 seconds;

[0033] In step S11, the exposure mode is hard contact exposure, the exposure distance is 50-200 microns, the exposure dose is 230-600 mj, the developing solution is an alkaline solution of tetramethylammonium hydroxide or an organic solvent developing solution, and the developing time is 2 minutes 40 seconds-4 minutes.

[0034] Preferably, in step S12, the electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.147-0.212 A, and the electroplating time is 240-600 seconds.

[0035] In step S13, the acetone soaking time is 5-10 minutes, the etching solution is a Cu metal etching solution prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0036] Compared with the prior art, the present application has the following advantages:

[0037] 1. The present application uses a glass wafer as a substrate, and the low substrate loss of the glass wafer does not interfere with the operation of the electronic element, and the excellent physical properties and chemical stability are conducive to the long-term use of the electronic element.

[0038] 2. The present application uses non-photosensitive polyimide as a support layer for the top arched coil of the inductor, and the non-photosensitive polyimide after imidization has excellent physical properties, and can significantly improve the mechanical stability of the three-dimensional inductor as a support layer for the coil, and the non-photosensitive polyimide as a support layer for the inductor instead of a sacrificial layer eliminates the risk of inductor rupture caused by deformation stress during the removal process of the colloid.

[0039] 3. The present application selects wet development for the non-photosensitive polyimide coating, and compared with dry etching, wet etching has stronger etching ability, and the pattern side wall treated by wet etching often has a certain slope instead of a nearly vertical cross section, and this feature can improve the uniformity of subsequent thin film deposition and the step coverage of the pattern. Compared with the traditional photoresist, the non-photosensitive polyimide has a higher viscosity, and a thicker or higher viscosity photoresist layer will slow down the diffusion speed of the developing solution, so that the side wall is more likely to form an inclined surface during the developing process. By controlling the developing time of the non-photosensitive polyimide, the side wall forms an inclined surface, and in the subsequent step of coating the positive photoresist, the positive photoresist will be uniformly distributed on the inclined surface, and the three-dimensional coil can be prepared by one electroplating, thereby eliminating the dependence of the three-dimensional inductor on the high aspect ratio structure.

[0040] 4. Compared with the MEMS inductor prepared based on the UV-LIGA, TSV and DRIE process, the arch-shaped coil prepared by the method does not need to form a high-aspect-ratio pillar structure through long-time electroplating, reduces the process cost and complexity, improves the production efficiency of the device, and compared with the existing preparation process under the same conditions, the preparation time of the preparation method is shortened by 15-20%. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0042] Figure 1 It is an axial measurement schematic diagram of the coreless arch-shaped MEMS inductor of the present application.

[0043] Figure 2 It is a three-view schematic diagram of the coreless arch-shaped MEMS inductor of the present application.

[0044] Figure 3 It is a step S1 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0045] Figure 4 It is a step S2 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0046] Figure 5 It is a step S3 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0047] Figure 6 It is a step S4 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0048] Figure 7 It is a step S5 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0049] Figure 8 It is a step S6 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0050] Figure 9 It is a step S7 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0051] Figure 10 It is a step S8 effect schematic diagram of preparing the coreless arch-shaped MEMS inductor of the present application.

[0052] Figure 11Effect schematic diagram of step S9 for preparing the coreless arched MEMS inductor of the present application;

[0053] Figure 12 Effect schematic diagram of step S10 for preparing the coreless arched MEMS inductor of the present application;

[0054] Figure 13 Effect schematic diagram of step S11 for preparing the coreless arched MEMS inductor of the present application;

[0055] Figure 14 Effect schematic diagram of step S12 for preparing the coreless arched MEMS inductor of the present application;

[0056] Figure 15 Effect schematic diagram of step S13 for preparing the coreless arched MEMS inductor of the present application;

[0057] Figure 16 Test result diagram of the coreless arched MEMS inductor prepared in Embodiment 1 of the present application;

[0058] In the figure, a is a top view; b is a front view; c is a left view; 1 is a glass substrate; 2 is a Ti / Cu metal seed layer; 3 is a first positive photoresist; 4 is an inductor bottom coil groove; 5 is a first fuse pad groove; 50 is a first connecting line groove; 6 is a second fuse pad groove; 60 is a second connecting line groove; 7 is an inductor coil; 70 is an inductor bottom coil; 71 is an inductor top arched coil; 8 is a first fuse pad; 80 is a first connecting line; 9 is a second fuse pad; 90 is a second connecting line; 10 is a non-photosensitive polyimide coating; 11 is a second positive photoresist; 12 is a Cu metal seed layer; 13 is a third positive photoresist; 14 is an inductor top arched coil groove. DETAILED DESCRIPTION

[0059] In order to make the inventive purposes, technical solutions and beneficial technical effects of the present application clearer, the present application will be described in detail below in combination with specific embodiments. It should be understood that the embodiments described in the present specification are only for explaining the present application, and are not intended to limit the present application.

[0060] The present application provides a coreless arched MEMS inductor, comprising: a glass substrate, an inductor coil, a fuse pad, a non-photosensitive polyimide coating.

[0061] Specifically, the inductor coil 7 comprises an inductor bottom coil 70 and an inductor top arc coil 71, the fuse pad comprises a first fuse pad 8 and a first connecting line 80 thereof, and a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 are electroplated on the glass substrate 1, the two ends of the inductor coil 7 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, respectively, the non-photosensitive polyimide coating 10 is attached to the surface of the glass substrate 1 as a supporting layer of the inductor top arc coil 71, the inductor top arc coil 71 and the non-photosensitive polyimide coating 10 are in the same shape, and the top surface of the fuse pad and the top surface of the inductor top arc coil 71 are not covered by the non-photosensitive polyimide coating 10. Figure 1 It is an axial measurement schematic diagram of the coreless arc MEMS inductor of the application, Figure 2 It is a three-view schematic diagram of the coreless arc MEMS inductor of the application.

[0062] Specifically, the two ends of the inductor bottom coil 70 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, respectively.

[0063] It should be noted that when a silicon wafer is used as the substrate of the coreless three-dimensional inductor, the silicon wafer substrate will increase the loss of the inductor and reduce the quality factor of the inductor, while the low substrate loss of the glass wafer will not interfere with the operation of the electronic element, and the excellent physical properties and chemical stability are conducive to the long-term use of the electronic element, so the application adopts a glass wafer as the substrate.

[0064] The application also provides a preparation method of the coreless arc MEMS inductor, comprising the following steps:

[0065] Step S1, sequentially clean the glass substrate 1 with acetone, isopropyl alcohol and deionized water, and blow dry;

[0066] Step S2, magnetron sputter a layer of Ti or Ti+Cu metal seed layer 2 on the surface of the glass substrate 1;

[0067] Step S3, coat a layer of first positive photoresist 3 on the surface of the Ti or Ti+Cu metal seed layer 2, and bake, expose and develop to obtain the inductor bottom coil groove 4 and the first fuse pad groove 5, the first connecting line groove 50, the second fuse pad groove 6 and the second connecting line groove 60;

[0068] Step S4, electroplating in the inductor bottom coil groove 4 and the first fuse pad groove 5 and the second fuse pad groove 6 to obtain the inductor bottom coil 70 and the first fuse pad 8, the first connecting line 80, the second fuse pad 9 and the second connecting line 90, and the two ends of the inductor bottom coil 70 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9 respectively;

[0069] Step S5, removing the first positive photoresist 3 by using acetone to expose the Ti or Ti+Cu seed layer 2, and then removing the Ti or Ti+Cu seed layer 2 by using etching solution;

[0070] Step S6, spin-coating a layer of non-photosensitive polyimide coating 10 and baking, and then coating a layer of second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10 and baking;

[0071] Step S7, forming the support layer of the inductor top arch-shaped coil 71 and wrapping the fuse pad around the non-photosensitive polyimide coating 10 by exposure and development, and exposing the top of the fuse pad;

[0072] Step S8, removing the residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10 by using propylene glycol monomethyl ether acetate solution, and baking the non-photosensitive polyimide coating 10 at high temperature in an oxygen-free environment to complete imidization;

[0073] Step S9, magnetron sputtering a layer of Cu metal seed layer 12 on the surface of the non-photosensitive polyimide coating 10;

[0074] Step S10, coating a layer of third positive photoresist 13 on the surface of the Cu metal seed layer 12 and baking;

[0075] Step S11, forming the inductor top arch-shaped coil groove 14 by exposure and development;

[0076] Step S12, electroplating in the inductor top arch-shaped coil groove 14 to obtain the inductor top arch-shaped coil 71, so that the inductor top arch-shaped coil 71 and the inductor bottom coil 70 are closed to form a complete inductor coil 7 and realize electrical connection;

[0077] Step S13, removing the third positive photoresist 13 by using acetone, and then sequentially cleaning the surface by using isopropyl alcohol and deionized water to expose the Cu metal seed layer 12, and then removing the Cu metal seed layer 12 by using etching solution and slicing and bonding to obtain the arch-shaped MEMS inductor without magnetic core.

[0078] It should be noted that in step S1, Figure 3 The effect schematic diagram of step S1 for preparing the arch-shaped MEMS inductor without magnetic core according to the present application.

[0079] In step S2, the magnetron sputtering process parameters are as follows: the Ti sputtering power is 400 W to 600 W, the Ti sputtering rate is 2.04 Å / s to 3.14 Å / s, and the thickness is 500 Å to 1000 Å; the Cu sputtering power is 300 W to 600 W, the Cu sputtering rate is 3.68 Å / s to 6.59 Å / s, and the thickness is 1000 Å to 2000 Å.

[0080] It should be noted that the bonding effect of the glass wafer and the metal layer is an important factor for selecting the type of seed layer metal. Cu, as one of the most commonly used metals, has poor bonding force with the glass wafer. If Cu is selected as the seed layer of the substrate, the poor bonding force will easily cause the substrate to fall off, increasing the risk of process failure. To solve this problem, it is more feasible to select Ti, which has better bonding force with the glass wafer, as the seed layer of the substrate. Therefore, a layer of Ti is first sputtered as a primer layer by magnetron sputtering. Since the inductor bottom coil and the fuse pad are prepared by electroplating Cu, the growth rate of the same metal will be faster, so a layer of Cu can be optionally sputtered on the surface of the Ti layer by magnetron sputtering.

[0081] Figure 4 The effect schematic diagram of step S2 for preparing the coreless arched MEMS inductor according to the present application is shown in the figure.

[0082] In step S3, AZ positive photoresist is spin-coated or sprayed as the first positive photoresist, and the thickness of the first positive photoresist 3 is 5 μm to 15 μm; the baking temperature is 90 °C to 110 °C, the baking time is 200 s to 350 s, the exposure mode is hard contact exposure, the exposure distance is 50 μm to 200 μm, the exposure dose is 230 mj to 600 mj, the developing solution is an alkaline solution containing TMAH (tetramethylammonium hydroxide) or an organic solvent developing solution, and the developing time is 2 min 40 s to 4 min. Figure 5 The effect schematic diagram of step S3 for preparing the coreless arched MEMS inductor according to the present application is shown in the figure.

[0083] In step S4, the electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.182 A to 0.251 A, and the electroplating time is 200 s to 800 s. Figure 6 The effect schematic diagram of step S4 for preparing the coreless arched MEMS inductor according to the present application is shown in the figure.

[0084] In step S5, the acetone solution is soaked for 5 min to 10 min, and the etching solution is a Ti metal etching solution or a Ti metal etching solution and a Cu metal etching solution, wherein the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid, and the Ti metal etching solution is an HF aqueous solution, wherein the mass percentage of HF in the aqueous solution is 2% to 8%. Figure 7 The effect schematic diagram of step S5 for preparing the coreless arched MEMS inductor according to the present application is shown in the figure.

[0085] In step S6, a non-photosensitive polyimide is spin-coated, the thickness of the non-photosensitive polyimide coating 10 is 45-65 μm, the baking temperature is 110-140℃, and the baking time is 200-300 s; AZ positive photoresist is spin-coated or sprayed as a second positive photoresist, the thickness of the second positive photoresist 11 is 5-15 μm, the baking temperature is 90-110℃, and the baking time is 200-350 s. Figure 8 The effect schematic diagram of step S6 for preparing the coreless arched MEMS inductor according to the application is shown in FIG. 6.

[0086] In step S7, the exposure mode is hard contact exposure, the exposure distance is 50-200 μm, the exposure dose is 230-600 mj, the developing solution is an alkaline solution containing TMAH (tetramethylammonium hydroxide) or an organic solvent developing solution, and the developing time is determined according to the surface shape of the non-photosensitive polyimide coating 10 to be formed, for example, 3 min 20 s-4 min 40 s. Figure 9 The effect schematic diagram of step S7 for preparing the coreless arched MEMS inductor according to the application is shown in FIG. 7.

[0087] It should be noted that in steps S6 and S7, the non-photosensitive polyimide is used as the top arched coil support layer of the inductor, and wet development is selected. Compared with dry etching, wet etching has stronger etching ability, and the side wall of the processed pattern often has a certain slope rather than a nearly vertical cross section. This feature can improve the uniformity of subsequent thin film deposition and the step coverage of the pattern. Compared with traditional photoresist, the non-photosensitive polyimide has a higher viscosity. During the developing process, the diffusion speed of the developing solution is slowed down by the thick or excessively viscous photoresist layer, so that the side wall is more likely to form a slope during the developing process. By controlling the developing time of the non-photosensitive polyimide, the side wall forms a slope. In step S10 of spin-coating the positive photoresist, the positive photoresist is uniformly distributed on the slope, and the three-dimensional coil can be prepared by one-time electroplating, thereby eliminating the dependence of the three-dimensional inductor on high aspect ratio structures. In addition, the imidized non-photosensitive polyimide has excellent physical properties, and as the coil support layer, it can significantly improve the mechanical stability of the three-dimensional inductor. Moreover, the non-photosensitive polyimide is used as the inductor support layer rather than a sacrificial layer, thereby eliminating the risk of inductor rupture caused by deformation stress during the removal of the photoresist.

[0088] In step S8, the concentration of propylene glycol monomethyl ether acetate solution is 99.1%-99.9%, and the soaking time is 2 min 40 s-5 min 30 s; the baking temperature is 140-300℃, and the baking time is 6-9 h. It should be noted that the baking temperature is a gradual heating process from 140℃ to 300℃, rather than baking at a certain temperature between 140℃ and 300℃. Figure 10The step S8 effect schematic diagram for preparing the coreless arched MEMS inductor of the present application.

[0089] In step S9, the sputtering process parameters are as follows: the Cu sputtering power is 300W~600W, the Cu sputtering rate is 3.68Å / s~6.59Å / s, and the thickness is 500Å~1000Å. Figure 11 The step S9 effect schematic diagram for preparing the coreless arched MEMS inductor of the present application.

[0090] In step S10, AZ positive photoresist is spin-coated or sprayed as the third positive photoresist, the thickness of the third positive photoresist 13 is 5μm~15μm, the baking temperature is 90℃~110℃, and the baking time is 200s~350s. Figure 12 The step S10 effect schematic diagram for preparing the coreless arched MEMS inductor of the present application.

[0091] In step S11, the exposure mode is hard contact exposure, the exposure distance is 50μm~200μm, the exposure dose is 230mj~600mj, the developing solution is an alkaline solution containing TMAH (tetramethylammonium hydroxide) or an organic solvent developing solution, and the developing time is 2min40s~4min. Figure 13 The step S11 effect schematic diagram for preparing the coreless arched MEMS inductor of the present application.

[0092] In step S12, the electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.147A~0.212A, and the electroplating time is 240s~600s. Figure 14 The step S12 effect schematic diagram for preparing the coreless arched MEMS inductor of the present application.

[0093] In step S13, the acetone soaking time is 5min~10min, the etching solution is a Cu metal etching solution, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid. Figure 15 The step S13 effect schematic diagram for preparing the coreless arched MEMS inductor of the present application.

[0094] The prepared coreless arched MEMS inductor is tested for performance by using an E4990A vector network analyzer, and the performance test includes inductance value and quality factor, the test frequency is 1KHz ~ 100MHz, and the measurement interval is 0.2 MHz. Figure 16 The inductance value and quality factor curves of the test result diagram of the coreless arched MEMS inductor of Example 1 of the present application, Figure 16 are within the normal range, which belongs to a normal inductance curve, indicating that the performance of the prepared coreless arched MEMS inductor of the present application can meet the use requirements.

[0095] Compared with the MEMS inductor prepared based on the UV-LIGA, TSV and DRIE process, the arch-shaped coil prepared by the method does not need to form a high-aspect-ratio post structure through long-time electroplating, reduces the process cost and complexity, and improves the production efficiency of the device.

[0096] Embodiment 1

[0097] The coreless arch-shaped MEMS inductor comprises a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating.

[0098] Specifically, the inductor coil 7 comprises an inductor bottom coil 70 and an inductor top arch-shaped coil 71, the fuse pad comprises a first fuse pad 8 and a first connecting line 80 thereof, and a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 and the second fuse pad 9 are electroplated on the glass substrate 1, the two ends of the inductor coil 7 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, the non-photosensitive polyimide coating 10 is attached to the surface of the glass substrate 1 and serves as a support layer of the inductor top arch-shaped coil 71, the inductor top arch-shaped coil 71 and the non-photosensitive polyimide coating 10 are in the same shape, and the top surface of the fuse pad and the top surface of the inductor top arch-shaped coil 71 are not covered by the non-photosensitive polyimide coating 10.

[0099] A preparation method of a coreless arch-shaped MEMS inductor comprises the following steps:

[0100] In step S1, the glass substrate 1 is sequentially cleaned with acetone, isopropyl alcohol and deionized water, and then dried by blowing.

[0101] In step S2, a Ti metal seed layer 2 is magnetron sputtered on the surface of the glass substrate 1.

[0102] The sputtering process parameters are as follows: the Ti sputtering power is 400 W, the Ti sputtering rate is 2.04 Å / s, and the thickness is 500 Å.

[0103] In step S3, a first positive photoresist 3 is coated on the surface of the Ti metal seed layer 2, and then baked, exposed and developed to obtain an inductor bottom coil groove 4 and a first fuse pad groove 5, a first connecting line groove 50, a second fuse pad groove 6 and a second connecting line groove 60.

[0104] The spin-coated AZ positive photoresist is used as the first positive photoresist, the thickness of the first positive photoresist 3 is 5 μm, the baking temperature is 90 °C, the baking time is 200 s, the exposure mode is hard contact exposure, the exposure distance is 50 μm, the exposure dose is 230 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 2 min 40 s.

[0105] In step S4, the inductor bottom coil 70 and the first and second fuse pads 8 and 9 and the first and second connecting lines 80 and 90 are obtained by electroplating at the inductor bottom coil groove 4 and the first and second fuse pad grooves 5 and 6, and the two ends of the inductor bottom coil 70 are connected through the first and second connecting lines 80 and 90 and the first and second fuse pads 8 and 9, respectively.

[0106] The electroplating solution is a Cu-ion-containing electroplating solution, the electroplating current is 0.182 A, and the electroplating time is 200 s.

[0107] In step S5, the first positive photoresist 3 is removed using acetone to expose the Ti seed layer 2, and then the Ti seed layer 2 is removed using an etching solution.

[0108] The acetone solution is soaked for 5 min, and the etching solution is a Ti metal etching solution, which is an HF aqueous solution with a mass percentage of HF in the aqueous solution of 2%.

[0109] In step S6, a layer of non-photosensitive polyimide coating 10 is spin-coated and dried, and then a layer of second positive photoresist 11 is coated on the surface of the non-photosensitive polyimide coating 10 and dried.

[0110] The non-photosensitive polyimide is spin-coated, the thickness of the non-photosensitive polyimide coating 10 is 45 μm, the baking temperature is 110 °C, and the baking time is 200 s; the AZ positive photoresist is used as the second positive photoresist, the thickness of the second positive photoresist 11 is 5 μm, the baking temperature is 90 °C, and the baking time is 200 s.

[0111] In step S7, the support layer of the inductor top arch-shaped coil 71 is shaped by exposure and development, and the fuse pads are wrapped in the non-photosensitive polyimide coating 10, with the top of the fuse pads exposed.

[0112] The exposure mode is hard contact exposure, the exposure distance is 50 μm, the exposure dose is 230 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 3 min 20 s.

[0113] Step S8, using propylene glycol monomethyl ether acetate solution to remove the residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10, baking the non-photosensitive polyimide coating 10 at high temperature in an oxygen-free environment to complete the imidization;

[0114] The propylene glycol monomethyl ether acetate solution has a concentration of 99.1%, and the soaking time is 2min40s; the baking temperature is 140℃-300℃, and the baking time is 6h.

[0115] Step S9, magnetron sputtering a layer of Cu metal seed layer 12 on the surface of the non-photosensitive polyimide coating 10;

[0116] The sputtering process parameters are: Cu sputtering power is 300W, Cu sputtering rate is 3.68Å / s, and thickness is 500Å.

[0117] Step S10, coating a layer of third positive photoresist 13 on the surface of the Cu metal seed layer 12 and drying;

[0118] The AZ system positive photoresist is used as the third positive photoresist, the thickness of the third positive photoresist 13 is 5μm, the baking temperature is 90℃, and the baking time is 200s.

[0119] Step S11, forming an inductor top arched coil groove 14 by exposure and development;

[0120] The exposure method is hard contact exposure, the exposure distance is 50μm, the exposure dose is 230mj, the development solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the development time is 2min40s.

[0121] Step S12, electroplating to obtain an inductor top arched coil 71 at the inductor top arched coil groove 14, so that the inductor top arched coil 71 and the inductor bottom coil 70 are closed to form a complete inductor coil 7 and realize electrical connection;

[0122] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.147A, and the electroplating time is 240s.

[0123] Step S13, using acetone to remove the third positive photoresist 13, and sequentially using isopropyl alcohol and deionized water to clean the surface, exposing the Cu metal seed layer 12, and then using an etching solution to remove the Cu metal seed layer 12 and slice bonding to obtain a magnetic core-free arched MEMS inductor.

[0124] The acetone soaking time is 5min, the etching solution is a Cu metal etching solution, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid, and acetic acid.

[0125] Example 2

[0126] A coreless arched MEMS inductor, comprising: a glass substrate, an inductor coil, a fuse pad, a non-photosensitive polyimide coating layer;

[0127] Specifically, the inductor coil 7 comprises an inductor bottom coil 70 and an inductor top arched coil 71, the fuse pad comprises a first fuse pad 8 and a first connecting line 80 thereof, a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 and the first fuse pad 9 are electroplated on the glass substrate 1, the two ends of the inductor bottom coil 70 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9 respectively, the non-photosensitive polyimide coating layer 10 is attached to the surface of the glass substrate 1 as a support layer of the inductor top arched coil 71, the inductor top arched coil 71 and the non-photosensitive polyimide coating layer 10 are conformal, and the top surface of the fuse pad and the top surface of the inductor top arched coil 71 are not covered by the non-photosensitive polyimide coating layer 10.

[0128] A preparation method of a coreless arched MEMS inductor, comprising the following steps:

[0129] Step S1, sequentially clean the glass substrate 1 with acetone, isopropyl alcohol and deionized water, and blow dry;

[0130] Step S2, magnetron sputter a layer of Ti metal seed layer 2 on the surface of the glass substrate 1;

[0131] The sputtering process parameters are: Ti sputtering power is 600W, Ti sputtering rate is 3.14Å / s, and thickness is 1000Å.

[0132] Step S3, coat a layer of first positive photoresist 3 on the surface of the Ti metal seed layer 2, and bake, expose and develop to obtain an inductor bottom coil groove 4 and a first fuse pad groove 5, a first connecting line groove 50, a second fuse pad groove 6 and a second connecting line groove 60;

[0133] Spray AZ positive photoresist as the first positive photoresist, the thickness of the first positive photoresist 3 is 15μm; the baking temperature is 110℃, the baking time is 350s, the exposure mode is hard contact exposure, the exposure distance is 200μm, the exposure dose is 600mj, the developing solution is organic solvent developing solution, and the developing time is 4min.

[0134] Step S4, electroplating to obtain an inductor bottom coil 70 and a first fuse pad 8, a first connecting line 80, a second fuse pad 9 and a second connecting line 90 at the inductor bottom coil groove 4 and the first fuse pad groove 5 and the second fuse pad groove 6, the two ends of the inductor bottom coil 70 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9 respectively;

[0135] The electroplating solution is a Cu-ion-containing electroplating solution, the electroplating current is 0.251 A, and the electroplating time is 800 s.

[0136] Step S5, the first positive photoresist 3 is removed by using acetone, the Ti seed layer 2 is exposed, and then the Ti seed layer 2 is removed by using an etching solution;

[0137] The acetone solution immersion time is 10 min, the etching solution is a Ti metal etching solution, and the Ti metal etching solution is an HF aqueous solution, wherein the mass percentage of HF in the aqueous solution is 8%.

[0138] Step S6, a layer of non-photosensitive polyimide coating 10 is spin-coated and dried; a layer of second positive photoresist 11 is further coated on the surface of the non-photosensitive polyimide coating 10 and dried;

[0139] The non-photosensitive polyimide is spin-coated, the thickness of the non-photosensitive polyimide coating 10 is 65 μm, the baking temperature is 140°C, and the baking time is 300 s; the AZ positive photoresist is sprayed as the second positive photoresist, the thickness of the second positive photoresist 11 is 15 μm, the baking temperature is 110°C, and the baking time is 350 s.

[0140] Step S7, the support layer of the inductor top arc-shaped coil 71 is shaped by exposure and development, and the periphery of the fuze pad is wrapped in the non-photosensitive polyimide coating 10, and the top of the fuze pad is exposed;

[0141] The exposure mode is hard contact exposure, the exposure distance is 200 μm, the exposure dose is 600 mj, the development solution is an organic solvent development solution, and the development time is 4 min 40 s.

[0142] Step S8, the residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10 is removed by using a propylene glycol monomethyl ether acetate solution, and the non-photosensitive polyimide coating 10 is high-temperature baked in an oxygen-free environment to complete imidization;

[0143] The propylene glycol monomethyl ether acetate solution has a concentration of 99.9%, and the immersion time is 5 min 30 s; the baking temperature is 140°C-300°C, and the baking time is 9 h.

[0144] Step S9, a Cu metal seed layer 12 is magnetron sputtered on the surface of the non-photosensitive polyimide coating 10;

[0145] The sputtering process parameters are as follows: the Cu sputtering power is 600 W, the Cu sputtering rate is 6.59 Å / s, and the thickness is 1000 Å.

[0146] Step S10, a third positive photoresist 13 is coated on the surface of the Cu metal seed layer 12 and dried;

[0147] The third positive photoresist AZ is sprayed, the thickness of the third positive photoresist 13 is 15 μm, the baking temperature is 110℃, and the baking time is 350 s.

[0148] In step S11, the top arched coil groove 14 of the inductor is formed by exposure and development.

[0149] The exposure mode is hard contact exposure, the exposure distance is 200 μm, the exposure dose is 600 mj, the developing solution is an organic solvent developing solution, and the developing time is 4 min.

[0150] In step S12, the top arched coil 71 of the inductor is obtained by electroplating at the top arched coil groove 14 of the inductor, so that the top arched coil 71 of the inductor and the bottom coil 70 of the inductor are closed to form a complete inductor coil 7 and achieve electrical connection.

[0151] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.212 A, and the electroplating time is 600 s.

[0152] In step S13, the third positive photoresist 13 is removed by using acetone, and the surface is sequentially cleaned by using isopropyl alcohol and deionized water to expose the Cu metal seed layer 12, and then the Cu metal seed layer 12 is removed by using an etching solution, slicing and bonding to obtain a magnetic core-free arched MEMS inductor.

[0153] The acetone soaking time is 10 min, the etching solution is a Cu metal etching solution, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0154] Embodiment 3

[0155] The magnetic core-free arched MEMS inductor comprises a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating.

[0156] Specifically, the inductor coil 7 comprises an inductor bottom coil 70 and an inductor top arched coil 71, the fuse pad comprises a first fuse pad 8 and a first connecting line 80 thereof, and a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 and the second fuse pad 9 are electroplated on the glass substrate 1, the two ends of the inductor coil 7 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, respectively, the non-photosensitive polyimide coating 10 is attached to the surface of the glass substrate 1 as a support layer of the inductor top arched coil 71, the inductor top arched coil 71 and the non-photosensitive polyimide coating 10 are in the same shape, and the top surface of the fuse pad and the top surface of the inductor top arched coil 71 are not covered by the non-photosensitive polyimide coating 10.

[0157] A preparation method of a magnetic core-free arched MEMS inductor comprises the following steps:

[0158] Step S1, clean the glass substrate 1 with acetone, isopropyl alcohol and deionized water in sequence, and dry it by blowing;

[0159] Step S2, magnetron sputter a layer of Ti metal seed layer 2 on the surface of the glass substrate 1;

[0160] The sputtering process parameters are: Ti sputtering power is 500W, Ti sputtering rate is 2.59Å / s, and thickness is 750Å.

[0161] Step S3, coat a layer of first positive photoresist 3 on the surface of the Ti metal seed layer 2, dry, expose, and develop to obtain the inductor bottom coil groove 4 and the first fuse pad groove 5, the first connecting line groove 50, the second fuse pad groove 6, and the second connecting line groove 60;

[0162] The first positive photoresist is spin-coated AZ positive photoresist, and the thickness of the first positive photoresist 3 is 10μm; the baking temperature is 100℃, the baking time is 275s, the exposure mode is hard contact exposure, the exposure distance is 125μm, the exposure dose is 415mj, the developing solution is an alkaline solution containing TMAH, i.e. tetramethylammonium hydroxide, and the developing time is 3min20s.

[0163] Step S4, electroplate to obtain the inductor bottom coil 70 and the first fuse pad 8, the first connecting line 80, the second fuse pad 9, and the second connecting line 90 at the inductor bottom coil groove 4 and the first fuse pad groove 5 and the second fuse pad groove 6, and the two ends of the inductor bottom coil 70 are connected through the first connecting line 80, the second connecting line 90, and the first fuse pad 8 and the second fuse pad 9 respectively;

[0164] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.217A, and the electroplating time is 500s.

[0165] Step S5, remove the first positive photoresist 3 using acetone to expose the Ti seed layer 2, and then remove the Ti seed layer 2 using an etching solution;

[0166] The acetone solution immersion time is 7.5min, the etching solution is a Ti metal etching solution, and the Ti metal etching solution is an HF aqueous solution, in which the mass percentage of HF in the aqueous solution is 5%.

[0167] Step S6, spin-coat a layer of non-photosensitive polyimide coating 10 and dry it; then coat a layer of second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10 and dry it;

[0168] The non-photosensitive polyimide is spin-coated, the thickness of the non-photosensitive polyimide coating 10 is 55 μm, the baking temperature is 125 °C, and the baking time is 250 s; the AZ positive photoresist is spin-coated as the second positive photoresist, the thickness of the second positive photoresist 11 is 10 μm, the baking temperature is 100 °C, and the baking time is 275 s.

[0169] In step S7, the support layer of the top arc-shaped coil 71 of the inductor is shaped by exposure and development, and the fuse pad is wrapped in the non-photosensitive polyimide coating 10 around the fuse pad, and the top of the fuse pad is exposed.

[0170] The exposure mode is hard contact exposure, the exposure distance is 125 μm, the exposure dose is 415 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 4 min.

[0171] In step S8, the propylene glycol monomethyl ether acetate solution is used to remove the residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10, and the non-photosensitive polyimide coating 10 is baked at high temperature in an oxygen-free environment to complete imidization.

[0172] The concentration of the propylene glycol monomethyl ether acetate solution is 99.5%, the soaking time is 4 min 5 s, the baking temperature is 140 °C to 300 °C, and the baking time is 7.5 h.

[0173] In step S9, a Cu metal seed layer 12 is sputtered on the surface of the non-photosensitive polyimide coating 10.

[0174] The sputtering process parameters are as follows: the Cu sputtering power is 450 W, the Cu sputtering rate is 5.14 Å / s, and the thickness is 750 Å.

[0175] In step S10, a third positive photoresist 13 is coated on the surface of the Cu metal seed layer 12 and dried.

[0176] The AZ positive photoresist is spin-coated as the third positive photoresist, the thickness of the third positive photoresist 13 is 10 μm, the baking temperature is 100 °C, and the baking time is 275 s.

[0177] In step S11, the top arc-shaped coil groove 14 of the inductor is formed by exposure and development.

[0178] The exposure mode is hard contact exposure, the exposure distance is 125 μm, the exposure dose is 415 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 3 min 20 s.

[0179] Step S12, electroplating at the top arched coil groove 14 of the inductor to obtain the top arched coil 71 of the inductor, so that the top arched coil 71 of the inductor and the bottom coil 70 of the inductor complete the closure to form a complete inductor coil 7, and realize electrical connection;

[0180] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.180 A, and the electroplating time is 420 s.

[0181] Step S13, using acetone to remove the third positive photoresist 13, and sequentially using isopropyl alcohol and deionized water to clean the surface, exposing the Cu metal seed layer 12, and then using etching solution to remove the Cu metal seed layer 12, slicing and bonding to obtain a magnetic core-free arched MEMS inductor.

[0182] The acetone soaking time is 7.5 min, the etching solution is a Cu metal etching solution, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0183] Example 4

[0184] A magnetic core-free arched MEMS inductor, comprising: a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating layer.

[0185] Specifically, the inductor coil 7 comprises an inductor bottom coil 70 and an inductor top arched coil 71, the fuse pad comprises a first fuse pad 8 and a first connecting line 80 thereof, and a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 and the second fuse pad 9 are electroplated on the glass substrate 1, the two ends of the inductor coil 7 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, respectively, the non-photosensitive polyimide coating layer 10 is attached to the surface of the glass substrate 1 as a supporting layer of the inductor top arched coil 71, the inductor top arched coil 71 and the non-photosensitive polyimide coating layer 10 are in the same shape, and the top surface of the fuse pad and the top surface of the inductor top arched coil 71 are not covered by the non-photosensitive polyimide coating layer 10.

[0186] A preparation method of a magnetic core-free arched MEMS inductor, comprising the following steps:

[0187] Step S1, sequentially using acetone, isopropyl alcohol, and deionized water to clean the glass substrate 1, and then blowing dry;

[0188] Step S2, magnetron sputtering a layer of Ti+Cu metal seed layer 2 on the surface of the glass substrate 1;

[0189] The sputtering process parameters are as follows: the Ti sputtering power is 400 W, the Ti sputtering rate is 2.04 Å / s, and the thickness is 500 Å; the Cu sputtering power is 300 W, the Cu sputtering rate is 3.68 Å / s, and the thickness is 1000 Å.

[0190] Step S3, a first positive photoresist 3 is coated on the surface of the Ti+Cu metal seed layer 2, and baking, exposure, and development are performed to obtain an inductor bottom coil groove 4 and a first fuse pad groove 5, a first connecting line groove 50, a second fuse pad groove 6, and a second connecting line groove 60;

[0191] The AZ positive photoresist is used as the first positive photoresist, and the thickness of the first positive photoresist 3 is 5 μm. The baking temperature is 90 °C, the baking time is 200 s, the exposure mode is hard contact exposure, the exposure distance is 50 μm, the exposure dose is 230 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 2 min 40 s.

[0192] Step S4, electroplating is performed at the inductor bottom coil groove 4 and the first fuse pad groove 5 and the second fuse pad groove 6 to obtain an inductor bottom coil 70 and a first fuse pad 8, a first connecting line 80, a second fuse pad 9, and a second connecting line 90. The two ends of the inductor bottom coil 70 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, respectively.

[0193] The electroplating solution is a Cu-ion-containing electroplating solution, the electroplating current is 0.182 A, and the electroplating time is 200 s.

[0194] Step S5, the first positive photoresist 3 is removed using acetone to expose the Ti+Cu seed layer 2, and then the Ti+Cu seed layer 2 is removed using an etching solution.

[0195] The acetone solution is soaked for 5 min, the etching solution is a Ti metal etching solution and a Cu metal etching solution. The Ti metal etching solution is an HF aqueous solution, in which the mass percentage of HF in the aqueous solution is 2%. The Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid, and acetic acid.

[0196] Step S6, a layer of non-photosensitive polyimide coating 10 is spin-coated and baked, and a second positive photoresist 11 is coated on the surface of the non-photosensitive polyimide coating 10 and baked.

[0197] The non-photosensitive polyimide is spin-coated, and the thickness of the non-photosensitive polyimide coating 10 is 45 μm. The baking temperature is 110 °C, and the baking time is 200 s. The AZ positive photoresist is used as the second positive photoresist, and the thickness of the second positive photoresist 11 is 5 μm. The baking temperature is 90 °C, and the baking time is 200 s.

[0198] Step S7, exposure and development are performed to form a support layer of the inductor top arch-shaped coil 71 and wrap the fuse pad around the non-photosensitive polyimide coating 10, and the top of the fuse pad is exposed.

[0199] The exposure mode is hard contact exposure, the exposure distance is 50μm, the exposure dose is 230mj, the developing solution is a basic solution containing TMAH, i.e. tetramethylammonium hydroxide, and the developing time is 3min20s.

[0200] Step S8, using propylene glycol monomethyl ether acetate solution to remove the residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10, baking the non-photosensitive polyimide coating 10 in an oxygen-free environment to complete the imidization;

[0201] The concentration of propylene glycol monomethyl ether acetate solution is 99.1%, and the soaking time is 2min40s; the baking temperature is 140℃~300℃, and the baking time is 6h.

[0202] Step S9, magnetron sputtering a layer of Cu metal seed layer 12 on the surface of the non-photosensitive polyimide coating 10;

[0203] The sputtering process parameters are: Cu sputtering power is 300W, Cu sputtering rate is 3.68Å / s, and thickness is 500Å.

[0204] Step S10, coating a layer of third positive photoresist 13 on the surface of the Cu metal seed layer 12 and drying;

[0205] The third positive photoresist 13 is AZ positive photoresist, the thickness of the third positive photoresist 13 is 5μm, the baking temperature is 90℃, and the baking time is 200s.

[0206] Step S11, forming an inductor top arched coil groove 14 by exposure and development;

[0207] The exposure mode is hard contact exposure, the exposure distance is 50μm, the exposure dose is 230mj, the developing solution is a basic solution containing TMAH, i.e. tetramethylammonium hydroxide, and the developing time is 2min40s.

[0208] Step S12, electroplating to obtain an inductor top arched coil 71 at the inductor top arched coil groove 14, so that the inductor top arched coil 71 and the inductor bottom coil 70 are closed to form a complete inductor coil 7 and realize electrical connection;

[0209] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.147A, and the electroplating time is 240s.

[0210] Step S13, using acetone to remove the third positive photoresist 13, and then sequentially using isopropyl alcohol and deionized water to clean the surface, exposing the Cu metal seed layer 12, and then using etching solution to remove the Cu metal seed layer 12 and slice bonding to obtain a magnetic core-free arched MEMS inductor.

[0211] The acetone soaking time is 5 min, and the etching solution is a Cu metal etching solution prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0212] Embodiment 5

[0213] The coreless arched MEMS inductor comprises a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating.

[0214] Specifically, the inductor coil 7 comprises an inductor bottom coil 70 and an inductor top arched coil 71, the fuse pad comprises a first fuse pad 8 and a first connecting line 80 thereof, and a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 and the second fuse pad 9 are electroplated on the glass substrate 1, the two ends of the inductor bottom coil 70 are connected through the first connecting line 80 and the second connecting line 90 and the first fuse pad 8 and the second fuse pad 9, the non-photosensitive polyimide coating 10 is attached to the surface of the glass substrate 1 as a support layer of the inductor top arched coil 71, the inductor top arched coil 71 and the non-photosensitive polyimide coating 10 are in the same shape, and the top surface of the fuse pad and the top surface of the inductor top arched coil 71 are not covered by the non-photosensitive polyimide coating 10.

[0215] A preparation method of a coreless arched MEMS inductor comprises the following steps:

[0216] In step S1, the glass substrate 1 is sequentially cleaned with acetone, isopropyl alcohol and deionized water, and then dried by blowing.

[0217] In step S2, a Ti+Cu metal seed layer 2 is magnetron sputtered on the surface of the glass substrate 1.

[0218] The sputtering process parameters are as follows: the Ti sputtering power is 600 W, the Ti sputtering rate is 3.14 Å / s, and the thickness is 1000 Å; the Cu sputtering power is 600 W, the Cu sputtering rate is 6.59 Å / s, and the thickness is 2000 Å.

[0219] In step S3, a first positive photoresist 3 is coated on the surface of the Ti+Cu metal seed layer 2, and then baked, exposed and developed to obtain an inductor bottom coil groove 4 and a first fuse pad groove 5, a first connecting line groove 50, a second fuse pad groove 6 and a second connecting line groove 60.

[0220] The first positive photoresist 3 is an AZ series positive photoresist, and the thickness of the first positive photoresist 3 is 15 μm; the baking temperature is 110°C, the baking time is 350 s, the exposure mode is hard contact exposure, the exposure distance is 200 μm, the exposure dose is 600 mj, the developing solution is an organic solvent developing solution, and the developing time is 4 min.

[0221] Step S4, electroplating in the inductor bottom coil groove 4 and the first fuse pad groove 5, the second fuse pad groove 6 to obtain the inductor bottom coil 70 and the first fuse pad 8, the first connecting line 80, the second fuse pad 9, the second connecting line 90, the two ends of the inductor bottom coil 70 are connected through the first connecting line 80, the second connecting line 90 and the first fuse pad 8, the second fuse pad 9 respectively;

[0222] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.251A, and the electroplating time is 800s.

[0223] Step S5, using acetone to remove the first positive photoresist 3, exposing the Ti+Cu seed layer 2, and then using an etching solution to remove the Ti+Cu seed layer 2;

[0224] The acetone solution immersion time is 10min, the etching solution is a Ti metal etching solution and a Cu metal etching solution, the Ti metal etching solution is an HF aqueous solution, and the mass percentage of HF in the aqueous solution is 8%, and the Cu metal etching solution is mixed by nitric acid, phosphoric acid and acetic acid.

[0225] Step S6, spin coating a layer of non-photosensitive polyimide coating 10 and baking; coating a layer of second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10 and baking;

[0226] The non-photosensitive polyimide is spin coated, the thickness of the non-photosensitive polyimide coating 10 is 65μm, the baking temperature is 140℃, and the baking time is 300s; the AZ positive photoresist is sprayed as the second positive photoresist, the thickness of the second positive photoresist 11 is 15μm, the baking temperature is 110℃, and the baking time is 350s.

[0227] Step S7, through exposure and development, the support layer of the inductor top arch-shaped coil 71 is shaped, and the fuse pad is wrapped in the non-photosensitive polyimide coating 10 around the top of the fuse pad is exposed;

[0228] The exposure mode is hard contact exposure, the exposure distance is 200μm, the exposure dose is 600mj, the developing solution is an organic solvent developing solution, and the developing time is 4min40s.

[0229] Step S8, using propylene glycol monomethyl ether acetate solution to remove the residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10, and baking the non-photosensitive polyimide coating 10 at high temperature in an oxygen-free environment to complete imidization;

[0230] The propylene glycol monomethyl ether acetate solution has a concentration of 99.9% and an immersion time of 5min30s; the baking temperature is 140℃~300℃, and the baking time is 9h.

[0231] Step S9, magnetron sputtering a Cu metal seed layer 12 on the surface of the non-photosensitive polyimide coating 10;

[0232] The sputtering process parameters are as follows: Cu sputtering power is 600 W, Cu sputtering rate is 6.59 Å / s, and thickness is 1000 Å.

[0233] Step S10, coating a third positive photoresist 13 on the surface of the Cu metal seed layer 12, and baking;

[0234] The third positive photoresist 13 is AZ positive photoresist, the thickness of the third positive photoresist 13 is 15 μm, the baking temperature is 110°C, and the baking time is 350 s.

[0235] Step S11, forming an inductor top arched coil groove 14 by exposure and development;

[0236] The exposure method is hard contact exposure, the exposure distance is 200 μm, the exposure dose is 600 mj, the development solution is an organic solvent development solution, and the development time is 4 min.

[0237] Step S12, electroplating to obtain an inductor top arched coil 71 at the inductor top arched coil groove 14, so that the inductor top arched coil 71 and the inductor bottom coil 70 are closed to form a complete inductor coil 7 and realize electrical connection;

[0238] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.212 A, and the electroplating time is 600 s.

[0239] Step S13, removing the third positive photoresist 13 using acetone, and sequentially using isopropyl alcohol and deionized water to clean the surface, exposing the Cu metal seed layer 12, then removing the Cu metal seed layer 12 using an etching solution, slicing and bonding to obtain a magnetic core-free arched MEMS inductor.

[0240] The acetone soaking time is 10 min, the etching solution is a Cu metal etching solution, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0241] Example 6

[0242] A magnetic core-free arched MEMS inductor, comprising: a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating;

[0243] Specifically, the inductor coil 7 includes an inductor bottom coil 70 and an inductor top arc coil 71, the fuse pad includes a first fuse pad 8 and a first connecting line 80 thereof, a second fuse pad 9 and a second connecting line 90 thereof, the inductor bottom coil 70 and the first fuse pad 8 are electroplated on the glass substrate 1, the first fuse pad 9, two ends of the inductor coil 7 are connected through the first connecting line 80, the second connecting line 90 and the first fuse pad 8, the second fuse pad 9, respectively, the non-photosensitive polyimide coating 10 is attached to the surface of the glass substrate 1 as a supporting layer of the inductor top arc coil 71, the inductor top arc coil 71 and the non-photosensitive polyimide coating 10 are in the same shape, and the top surface of the fuse pad and the top surface of the inductor top arc coil 71 are not covered by the non-photosensitive polyimide coating 10.

[0244] A preparation method of a coreless arc MEMS inductor, comprising the following steps:

[0245] In step S1, the glass substrate 1 is sequentially cleaned with acetone, isopropyl alcohol and deionized water, and then dried by blowing.

[0246] In step S2, a Ti+Cu metal seed layer 2 is magnetron sputtered on the surface of the glass substrate 1.

[0247] The sputtering process parameters are as follows: the Ti sputtering power is 500 W, the Ti sputtering rate is 2.59 Å / s, and the thickness is 750 Å; the Cu sputtering power is 450 W, the Cu sputtering rate is 5.14 Å / s, and the thickness is 1500 Å.

[0248] In step S3, a first positive photoresist 3 is coated on the surface of the Ti+Cu metal seed layer 2, and then baked, exposed and developed to obtain an inductor bottom coil groove 4 and a first fuse pad groove 5, a first connecting line groove 50, a second fuse pad groove 6 and a second connecting line groove 60.

[0249] The first positive photoresist 3 is an AZ positive photoresist, and the thickness of the first positive photoresist 3 is 10 μm; the baking temperature is 100°C, the baking time is 275 s, the exposure mode is hard contact exposure, the exposure distance is 125 μm, the exposure dose is 415 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 3 min 20 s.

[0250] In step S4, the inductor bottom coil 70 and the first fuse pad 8, the first connecting line 80, the second fuse pad 9 and the second connecting line 90 are electroplated at the inductor bottom coil groove 4 and the first fuse pad groove 5 and the second fuse pad groove 6, and two ends of the inductor bottom coil 70 are connected through the first connecting line 80, the second connecting line 90 and the first fuse pad 8, the second fuse pad 9, respectively.

[0251] The electroplating solution is an electroplating solution containing Cu ions, the electroplating current is 0.217 A, and the electroplating time is 500 s.

[0252] Step S5, remove the first positive photoresist 3 using acetone to expose the Ti+Cu seed layer 2, and then remove the Ti+Cu seed layer 2 using an etching solution;

[0253] The acetone solution immersion time is 7.5 min, the etching solution is a Ti metal etching solution and a Cu metal etching solution, the Ti metal etching solution is an aqueous HF solution, and the mass percentage of HF in the aqueous solution is 5%, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0254] Step S6, spin a layer of non-photosensitive polyimide coating 10 and dry; then coat a second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10 and dry;

[0255] The non-photosensitive polyimide is spin-coated, the thickness of the non-photosensitive polyimide coating 10 is 55 μm, the baking temperature is 125°C, and the baking time is 250 s; the AZ positive photoresist is spin-coated as the second positive photoresist, the thickness of the second positive photoresist 11 is 10 μm, the baking temperature is 100°C, and the baking time is 275 s.

[0256] Step S7, by exposure and development, the support layer of the inductor top arc-shaped coil 71 is shaped, and the fuse pad is wrapped in the non-photosensitive polyimide coating 10 around the fuse pad, and the top of the fuse pad is exposed;

[0257] The exposure method is hard contact exposure, the exposure distance is 125 μm, the exposure dose is 415 mj, the development solution is an alkaline solution containing TMAH, i.e. tetramethylammonium hydroxide, and the development time is 4 min.

[0258] Step S8, use propylene glycol monomethyl ether acetate solution to remove residual second positive photoresist 11 on the surface of the non-photosensitive polyimide coating 10, and bake the non-photosensitive polyimide coating 10 at high temperature in an oxygen-free environment to complete imidization;

[0259] The propylene glycol monomethyl ether acetate solution has a concentration of 99.5% and an immersion time of 4 min 5 s; the baking temperature is 140°C-300°C, and the baking time is 7.5 h.

[0260] Step S9, magnetron sputtering a layer of Cu metal seed layer 12 on the surface of the non-photosensitive polyimide coating 10;

[0261] The sputtering process parameters are: Cu sputtering power is 450 W, Cu sputtering rate is 5.14 Å / s, and thickness is 750 Å.

[0262] Step S10, a third positive photoresist 13 is coated on the surface of the Cu metal seed layer 12, and is baked;

[0263] The AZ positive photoresist is spin-coated as the third positive photoresist, and the thickness of the third positive photoresist 13 is 10 μm, the baking temperature is 100 °C, and the baking time is 275 s.

[0264] Step S11, the inductor top arched coil groove 14 is formed by exposure and development;

[0265] The exposure mode is hard contact exposure, the exposure distance is 125 μm, the exposure dose is 415 mj, the developing solution is an alkaline solution containing TMAH, i.e., tetramethylammonium hydroxide, and the developing time is 3 min 20 s.

[0266] Step S12, the inductor top arched coil 71 is obtained by electroplating at the inductor top arched coil groove 14, so that the inductor top arched coil 71 and the inductor bottom coil 70 are closed to form a complete inductor coil 7 and realize electrical connection;

[0267] The electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.180 A, and the electroplating time is 420 s.

[0268] Step S13, the third positive photoresist 13 is removed using acetone, and the surface is sequentially cleaned using isopropyl alcohol and deionized water to expose the Cu metal seed layer 12, and then the Cu metal seed layer 12 is removed using an etching solution, and slicing and bonding are performed to obtain a magnetic core-free arched MEMS inductor.

[0269] The acetone soaking time is 7.5 min, the etching solution is a Cu metal etching solution, and the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid.

[0270] The magnetic core-free arched MEMS inductors prepared in Examples 1-6 are tested for performance using an E4990A vector network analyzer, and the performance test includes inductance value and quality factor, the test frequency is 1 KHz-100 MHz, the measurement interval is 0.2 MHz, and the inductance value and quality factor curves of the magnetic core-free arched MEMS inductor prepared in Example 1 are shown in FIG. 2. Figure 16 The inductance value and quality factor curves are within the normal range.

[0271] Compared with the MEMS inductor prepared based on the UV-LIGA, TSV and DRIE processes, the arched coil prepared in Examples 1-6 does not need to go through a long electroplating process to form a high aspect ratio post structure, which reduces the process cost and complexity while improving the production efficiency of the device. Compared with the existing preparation process under the same conditions, the preparation time of Examples 1-6 is shortened by 15%-20%.

[0272] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope determined by the claims.

Claims

1. A method of fabricating a coreless arched MEMS inductor, comprising: The inductor comprises a glass substrate, an inductor coil, a fuse pad, and a non-photosensitive polyimide coating; the inductor coil comprises an inductor bottom coil and an inductor top arched coil, the fuse pad comprises a first fuse pad and a first connecting line thereof, and a second fuse pad and a second connecting line thereof, the inductor bottom coil and the first and second fuse pads are electroplated on the glass substrate, one end of the inductor bottom coil is connected to the first fuse pad through the first connecting line, and the other end of the inductor bottom coil is connected to the second fuse pad through the second connecting line, the non-photosensitive polyimide coating is attached to the surface of the glass substrate as a support layer of the inductor top arched coil, the inductor top arched coil and the non-photosensitive polyimide coating are shaped together, and the top surface of the fuse pad and the top surface of the inductor top arched coil are not covered by the non-photosensitive polyimide coating; The method comprises the following steps: Step S1, sequentially clean the glass substrate with acetone, isopropyl alcohol, and deionized water, and blow dry; Step S2, magnetron sputter a layer of Ti or Ti+Cu metal seed layer on the surface of the glass substrate; Step S3, coat a layer of first positive photoresist on the surface of the Ti or Ti+Cu metal seed layer, dry, expose, and develop to obtain inductor bottom coil grooves and first fuse pad grooves, first connecting line grooves, second fuse pad grooves, and second connecting line grooves; Step S4, electroplate the inductor bottom coil and the first and second fuse pads and the first and second connecting lines in the inductor bottom coil grooves and the first fuse pad grooves, the first connecting line grooves, the second fuse pad grooves, and the second connecting line grooves, one end of the inductor bottom coil being connected to the first fuse pad through the first connecting line and the other end of the inductor bottom coil being connected to the second fuse pad through the second connecting line; Step S5, remove the first positive photoresist using acetone to expose the Ti or Ti+Cu seed layer, and then remove the Ti or Ti+Cu seed layer using an etching solution; Step S6, spin coat a layer of non-photosensitive polyimide coating and dry, and coat a layer of second positive photoresist on the surface of the non-photosensitive polyimide coating and dry; Step S7, expose and develop to shape the support layer of the inductor top arched coil and wrap the fuse pad in the non-photosensitive polyimide coating, and expose the top of the fuse pad; Step S8, remove residual second positive photoresist on the surface of the non-photosensitive polyimide coating using propylene glycol monomethyl ether acetate solution, and bake the non-photosensitive polyimide coating at high temperature in an oxygen-free environment to complete imidization; Step S9, magnetron sputter a layer of Cu metal seed layer on the surface of the non-photosensitive polyimide coating; Step S10, coat a layer of third positive photoresist on the surface of the Cu metal seed layer and dry; Step S11, expose and develop to form inductor top arched coil grooves; Step S12, electroplate the inductor top arched coil in the inductor top arched coil grooves to complete the closure of the inductor top arched coil and the inductor bottom coil to form a complete inductor coil and achieve electrical connection. Step S13, using acetone to remove the third positive photoresist, and sequentially using isopropyl alcohol and deionized water to clean the surface, exposing the Cu metal seed layer, and then using an etching solution to remove the Cu metal seed layer, slicing and bonding to obtain a non-magnetic core arched MEMS inductor.

2. The method of claim 1, wherein, In the step S2, the magnetron sputtering process parameters are as follows: the Ti sputtering power is 400 W-600 W, the Ti sputtering rate is 2.04 Å / s-3.14 Å / s, and the thickness is 500 Å-1000 Å; the Cu sputtering power is 300 W-600 W, the Cu sputtering rate is 3.68 Å / s-6.59 Å / s, and the thickness is 1000 Å-2000 Å.

3. The method of claim 1, wherein, In the step S3, the first positive photoresist is AZ positive photoresist which is spin-coated or sprayed, the thickness of the first positive photoresist is 5 μm-15 μm, the drying temperature is 90 °C-110 °C, the drying time is 200 s-350 s, the exposure mode is hard contact exposure, the exposure distance is 50 μm-200 μm, the exposure dose is 230 mj-600 mj, the developing solution is a basic solution of tetramethylammonium hydroxide or an organic solvent developing solution, and the developing time is 2 min 40 s-4 min. In the step S4, the electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.182 A-0.251 A, and the electroplating time is 200 s-800 s. In the step S5, the acetone solution immersion time is 5 min-10 min, and the etching solution is a Ti metal etching solution or a Ti metal etching solution and a Cu metal etching solution, wherein the Cu metal etching solution is prepared by mixing nitric acid, phosphoric acid and acetic acid, and the Ti metal etching solution is an HF aqueous solution, wherein the mass percentage of HF in the aqueous solution is 2%-8%.

4. The method of claim 1, wherein, In the step S6, the thickness of the non-photosensitive polyimide coating is 45 μm-65 μm, the drying temperature is 110 °C-140 °C, the drying time is 200 s-300 s, the second positive photoresist is AZ positive photoresist which is spin-coated or sprayed, the thickness of the second positive photoresist is 5 μm-15 μm, the drying temperature is 90 °C-110 °C, and the drying time is 200 s-350 s.

5. The method of claim 1, wherein, In the step S7, the exposure mode is hard contact exposure, the exposure distance is 50 μm-200 μm, the exposure dose is 230 mj-600 mj, the developing solution is a basic solution of tetramethylammonium hydroxide or an organic solvent developing solution, and the developing time is 3 min 20 s-4 min 40 s.

6. The method of claim 1, wherein, In the step S8, the concentration of the propylene glycol monomethyl ether acetate solution is 99.1%-99.9%, the immersion time is 2 min 40 s-5 min 30 s, the baking temperature is 140 °C-300 °C, and the baking time is 6 h-9 h.

7. The method of claim 1, wherein, In the step S9, the magnetron sputtering process parameters are as follows: the Cu sputtering power is 300 W-600 W, the Cu sputtering rate is 3.68 Å / s-6.59 Å / s, and the thickness is 500 Å-1000 Å. In the step S10, the AZ system positive photoresist is spin-coated or sprayed as the third positive photoresist, the thickness of the third positive photoresist is 5-15 μm, the drying temperature is 90-110 ℃, and the drying time is 200-350 s; In the step S11, the exposure mode is hard contact exposure, the exposure distance is 50-200 μm, the exposure dose is 230-600 mj, the developing solution is an alkaline solution of tetramethylammonium hydroxide or an organic solvent developing solution, and the developing time is 2 min 40 s-4 min.

8. The method of claim 1, wherein, In the step S12, the electroplating solution is a Cu ion-containing electroplating solution, the electroplating current is 0.147-0.212 A, and the electroplating time is 240-600 s. In the step S13, the acetone immersion time is 5-10 min, and the etching solution is a Cu metal etching solution prepared by mixing nitric acid, phosphoric acid and acetic acid.

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