Preparation method of three-dimensional inductor

Abstract

This invention provides a method for fabricating a three-dimensional inductor, comprising: providing a substrate, wherein an annular trench is formed on a first surface; forming a lead zirconate titanate thin film to cover the inner wall of the annular trench to form a magnetic core of the three-dimensional inductor; forming a plurality of through holes at least partially surrounding the annular trench, the depth of the through holes being greater than or equal to the depth of the annular trench, and forming a first conductive wire within the through holes; forming a plurality of second conductive wires on the first surface to connect the first conductive wire; thinning the substrate from a second surface to expose the first conductive wire, and forming second conductive wires to connect the first conductive wire, wherein the first and second conductive wires surround the magnetic core and serve as the coil of the three-dimensional inductor. In this invention, the thin film structure formed by covering the inner wall of the annular trench with a lead zirconate titanate thin film as the magnetic core is not only easier to implement in terms of manufacturing process, but also simultaneously improves the inductance value and quality factor of the three-dimensional inductor.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to a method for fabricating a three-dimensional inductor. Background Technology

[0002] Inductors are one of the essential basic components in integrated circuits, playing an important role in switching power supplies and radio frequency circuits.

[0003] As the integration density of integrated circuits increases, the feature size of semiconductor devices will reach its physical limit. To further improve performance and integration density, researchers have begun to integrate chips in three dimensions. Compared with planar inductors, three-dimensional inductors occupy a smaller area, which greatly improves the packaging density and inductance density per unit area. However, existing three-dimensional inductors cannot simultaneously achieve a large inductance value and a large quality factor, and this also leads to complex structural designs, which is not conducive to the manufacture of three-dimensional inductors. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating a three-dimensional inductor, so as to improve the performance of the three-dimensional inductor and facilitate its manufacturing.

[0005] To solve the above-mentioned technical problems, the present invention provides a method for fabricating a three-dimensional inductor, comprising:

[0006] A substrate is provided, the substrate having opposing first and second surfaces, wherein an annular trench is formed on the first surface;

[0007] A lead zirconate titanate thin film is formed to cover the inner wall of the annular trench to form the magnetic core of the three-dimensional inductor, and a first material layer is formed to cover the lead zirconate titanate thin film and fill the annular trench.

[0008] A plurality of through holes are formed to at least partially surround the annular groove, the depth of the through holes being greater than or equal to the depth of the annular groove, and a first conductor is formed within the through holes;

[0009] A plurality of second wires are formed on the first surface and the second surface respectively to connect to the first wire, and the first wire and the second wires surround the magnetic core as the coil of the three-dimensional inductor.

[0010] Optionally, the step of forming the magnetic core includes:

[0011] A patterned mask layer is formed to cover the first surface and expose the annular groove;

[0012] A lead zirconate titanate thin film is formed using a deposition process to cover the patterned mask layer and the inner wall of the annular trench;

[0013] Remove the patterned mask layer and use the lead zirconate titanate film within the annular trench as the magnetic core.

[0014] Optionally, the patterned mask layer also exposes the central region of the annular trench, on which the lead zirconate titanate film is formed and retained as part of the magnetic core.

[0015] Optionally, the material of the first material layer may include polyimide.

[0016] Optionally, the depth of the via is less than the thickness of the substrate, and the step of forming the first wire within the via includes:

[0017] A first dielectric layer is formed to cover the inner wall of the through hole and the surface of the first surface;

[0018] An adhesion layer and a seed layer are sequentially formed on the first medium layer;

[0019] A metal layer is formed on the seed layer using a chemical electroplating process, and the through-hole is filled to the top of the first surface;

[0020] The grinding process is performed with the first dielectric layer as the grinding stop layer, and the metal layer and seed layer in the through hole are used as the first conductive line.

[0021] Optionally, after forming the first conductor, a plurality of second conductors are formed on the first surface to connect the plurality of first conductors.

[0022] Optionally, after forming a plurality of the second wires on the first surface, the method further includes:

[0023] A carrier plate is provided, the carrier plate is attached to the first side, and then flipped so that the second side is facing up;

[0024] The second surface is thinned and ground until the first conductor is exposed.

[0025] Optionally, the second surface may be thinned and ground to expose the first conductor and the annular groove.

[0026] Optionally, the lead zirconate titanate film is formed on the thinned second surface to cover the middle region of the annular groove or the projected region corresponding to the middle region of the annular groove.

[0027] Optionally, the step of forming the second wire includes:

[0028] A second dielectric layer is formed to cover the surface of the substrate;

[0029] The second dielectric layer is graphically represented to form several trenches that connect to the first conductor;

[0030] A second conductor is formed within the trench, and the second conductor is connected to the first conductor.

[0031] In summary, this invention forms an annular trench on the first surface of a substrate, and a lead zirconate titanate thin film is formed on the inner wall of the annular trench to serve as the magnetic core of a three-dimensional inductor. A first material layer is then filled into the annular trench, and second wires are formed on the first and second surfaces respectively to connect to the first wires, forming a coil surrounding the magnetic core, thereby forming a three-dimensional inductor. The higher permeability of the lead zirconate titanate thin film compared to the substrate increases the inductance of the three-dimensional inductor. The higher dielectric constant of the lead zirconate titanate thin film compared to the substrate reduces eddy current losses, and the thinner film structure reduces core losses, thereby improving the quality factor. Furthermore, compared to using a solid structure (such as the substrate itself, air, or other materials) as the magnetic core, using a thin film structure formed by covering the inner wall of the annular trench with a lead zirconate titanate thin film as the magnetic core is not only easier to implement in terms of manufacturing process, but also simultaneously improves the inductance and quality factor of the three-dimensional inductor. Attached Figure Description

[0032] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention.

[0033] Figure 1 This embodiment provides a method for fabricating a three-dimensional inductor.

[0034] Figures 2a to 14b The diagram shows the structural schematic corresponding to the steps of the fabrication method of the three-dimensional inductor provided in this embodiment.

[0035] In the attached image:

[0036] 10-Substrate; 10a-First surface; 10b-Second surface; 11-Annular trench; 12-Intermediate region; 21-Patterned second mask layer; 22-Lead zirconate titanate thin film; 23-First material layer; 31-Through hole; 32-First dielectric layer; 33-First conductive line; 34-Second conductive line; 41-Carrier plate; 42-Second dielectric layer. Detailed Implementation

[0037] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0038] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature, unless otherwise expressly indicated.

[0039] Figure 1 This embodiment provides a method for fabricating a three-dimensional inductor.

[0040] like Figure 1 As shown, the method for fabricating a three-dimensional inductor provided in this embodiment includes:

[0041] S01: A substrate is provided, the substrate having opposing first and second surfaces, wherein an annular trench is formed on the first surface;

[0042] S02: Form a lead zirconate titanate film to cover the inner wall of the annular trench to form the magnetic core of the three-dimensional inductor, and form a first material layer to cover the lead zirconate titanate film and fill the annular trench;

[0043] S03: Form a plurality of through holes that at least partially surround the annular groove, wherein the depth of the through holes is greater than or equal to the depth of the annular groove, and form a first conductor within the through holes;

[0044] S04: A plurality of second wires are formed on the first surface and the second surface respectively to connect the first wire, and the first wire and the second wires surround the magnetic core as the coil of the three-dimensional inductor.

[0045] Figures 2a to 14b The diagram below shows the structural schematics corresponding to the steps of the fabrication method for the three-dimensional inductor provided in this embodiment. The following will be combined with... Figures 2a to 14b The fabrication method of the three-dimensional inductor is described in detail.

[0046] First, perform step S01, please refer to... Figure 2a and Figure 2b A substrate 10 is provided, the substrate 10 having a first surface 10a and a second surface 10b opposite to each other, and an annular groove 11 is formed on the first surface 10a.

[0047] The substrate 10 can be any suitable substrate material well known to those skilled in the art, such as at least one of the following materials: silicon, quartz, or glass. In this embodiment, the substrate 10 is described as being made of silicon. Figure 2a This is a cross-sectional schematic diagram showing an annular trench 11 formed on the substrate 10. Figure 2b This is a top view of a substrate 10 in which an annular trench 11 is formed.

[0048] Specifically, the step of forming an annular trench 11 on the first surface 10a of the substrate 10 may include: forming a first mask layer on the first surface 10a of the substrate 10; patterning the first mask layer to expose an annular pattern; then etching the exposed annular pattern using the first mask layer to form the annular trench 11; the first surface 10a surrounding the annular trench 11 may be the middle region 12 of the annular trench 11; and then removing the first mask layer. The shape of the annular pattern and the depth of the annular trench 11 are matched to the three-dimensional inductor to be formed, for subsequent formation of the magnetic core of the three-dimensional inductor. In this embodiment, the shape of the annular trench 11 (annular pattern) may be a U-shape, and the shape of the middle region 12 may be rectangular.

[0049] Next, step S02 is performed to form a lead zirconate titanate film 22 covering the inner wall of the annular groove 11 to form the magnetic core of the three-dimensional inductor, and to form a first material layer 23 covering the lead zirconate titanate film 22 and filling the annular groove 11.

[0050] The specific steps for forming the magnetic core may include: first, forming a patterned second mask layer 21 to cover the first surface 10a and expose the annular groove 11 (its opening region). In a preferred embodiment, please refer to... Figure 3 The patterned second mask layer 21 exposes the annular trench 11 and its intermediate region 12 (the region of the first surface 10a located in the middle of the annular trench 11) to further improve the performance (inductance value and quality factor) of the three-dimensional inductor.

[0051] Please refer to Figure 4 A lead zirconate titanate film 22 is formed using a deposition process to cover the patterned second mask layer 21, the inner wall of the annular trench 11, and the exposed first surface 10a. The lead zirconate titanate film 22 can be formed using any suitable deposition process, such as physical sputtering, hydrothermal deposition, or sol-gel deposition. The thickness of the formed lead zirconate titanate film 22 can be, for example, 0.2 μm to 0.8 μm, but is not limited to this. During the formation of the lead zirconate titanate film 22, the dielectric constant of the formed lead zirconate titanate film 22 can be increased by adjusting the process, thereby improving the performance (inductance value and quality factor) of the formed three-dimensional inductor. In this embodiment, a physical sputtering process can be used to form the lead zirconate titanate film 22 to improve its film quality.

[0052] Compared to using a lead zirconate titanate film 22 without it to form the magnetic core, using a lead zirconate titanate film 22 as the magnetic core can significantly improve both the inductance and quality factor of the three-dimensional inductor. However, it should be noted that as the thickness of the lead zirconate titanate film 22 increases, the inductance and quality factor of the three-dimensional inductor exhibit opposite trends. That is, as the thickness of the lead zirconate titanate film 22 increases, the magnetic permeability of the core increases, which is beneficial for increasing the inductance of the three-dimensional inductor, but it will slightly increase the core loss, relatively decreasing the quality factor. Therefore, when setting the thickness of the lead zirconate titanate film, its impact on the performance of the three-dimensional inductor must be comprehensively considered based on the above characteristics.

[0053] Please refer to Figure 5 The patterned second mask layer 21 is removed, and the remaining lead zirconate titanate film 22 is used as the core or part of the core of the three-dimensional inductor. Specifically, a wet process can be used to remove the patterned second mask layer 21, and simultaneously remove the lead zirconate titanate film 22 located on the patterned second mask layer 21. The lead zirconate titanate film 22 on the inner wall of the annular trench 11 and in the middle region 12 of the annular trench 11 is used as the core of the three-dimensional inductor.

[0054] Please refer to Figure 6 A first material layer 23 is formed to fill the annular groove 11. The first material layer 23 can preferably be a medium material that is easy to fill, such as polyimide. Polyimide is filled into the annular groove 11 using a spin-coating process, and then the polyimide outside the annular groove 11 is removed and cured, so that the top surface of the first material layer 23 is substantially flush with the first surface 10a. Alternatively, if a lead zirconate titanate film 22 is formed on the middle region 12 of the annular groove 11, the remaining thickness of the first material layer 23 can cover the lead zirconate titanate film 22 for isolation, which is also feasible.

[0055] Next, step S03 is performed to form a plurality of through holes 31 that at least partially surround the annular groove 11, the depth of the through holes 31 being greater than or equal to the depth of the annular groove 11, and a first conductor 33 being formed within the through holes 31.

[0056] In this embodiment, taking the example of a three-dimensional inductor coil extending in a strip shape, the steps for forming the first conductor 33 include: Please refer to... Figure 7A plurality of through holes 31 are formed on both sides of the annular groove 11. These through holes 31 may not penetrate the substrate 10 (the depth of the through hole 31 is less than the thickness of the substrate 10) to facilitate the formation of the first conductor 33, but the depth of the through hole 31 is greater than or equal to the depth of the annular groove 11 to facilitate the subsequent formation of a coil surrounding the magnetic core. These through holes 31 may be symmetrically arranged on both sides of the annular groove 11 and maintain a certain distance from the annular groove 11. The distance between the first through hole 31 and the last through hole 31 on each side is the length of the coil of the three-dimensional inductor. Specifically, in this embodiment, four through holes 31 are provided on each side of the annular groove 11 so that the number of turns of the coil is four.

[0057] Please refer to Figure 8 A first dielectric layer 32 is formed to cover the inner wall of the through-hole 31 and the surface of the first surface 10a. The first dielectric layer 32 can be any suitable insulating material, such as silicon oxide, and can be formed by vapor deposition to cover the inner wall of the through-hole 31 and the surface of the first surface 10a. The surface of the first surface 10a covered by the first dielectric layer 32 here also includes a first material layer 23 that is substantially flush with the first surface 10a and the surface of a thin lead zirconate titanate sheet.

[0058] Please refer to Figure 9 Taking the first conductor 33 as an example, where the material includes copper and copper is formed by chemical electroplating, the specific steps for forming the first conductor 33 in the through hole 31 include: forming an adhesion layer and a seed layer sequentially on the first dielectric layer 32. The material of the adhesion layer can be tantalum nitride, titanium tungstenide, or tungsten nitride, etc., and forming the adhesion layer and seed layer (material is copper) by physical sputtering process; forming a metal layer (copper) on the seed layer by chemical electroplating process, and filling the through hole 31 to the top of the first surface 10a; performing a grinding process with the first dielectric layer 32 as the grinding stop layer, and using the metal layer and seed layer in the through hole 31 as the first conductor 33.

[0059] Next, step S04 is executed, in which a plurality of second wires 34 are formed on the first surface 10a and the second surface 10b respectively to connect to the first wire 33, and the first wire 33 and the second wires 34 surround the magnetic core as the coil of the three-dimensional inductor.

[0060] Please refer to Figure 10 A plurality of second conductive lines 34 are formed on the first surface 10a to connect to the first conductive lines 33. The material of the second conductive lines 34 on the first surface 10a can be the same as that of the first conductive lines 33, and they are formed using a similar process. The specific steps may include: firstly, using a photolithography process to form a plurality of first trenches connecting the first conductive lines 33 on both sides in the first dielectric layer 32, with the two ends of the first trenches exposing the first conductive lines 33; then, forming an adhesion layer and a seed layer in sequence to cover the inner wall of the first trenches and the surface of the first dielectric layer 32; and then using a chemical electroplating process to form copper filling in the first trenches, and using the copper in the first trenches as the second conductive lines 34.

[0061] Next, the substrate 10 is thinned from the second surface 10b to expose the first conductive line 33, and a second conductive line 34 is formed to connect the first conductive line 33. The first conductive line 33 and the second conductive line 34 surround the magnetic core and serve as the coil of a three-dimensional inductor. For details, please refer to... Figure 11 The substrate 10 is thinned from the second surface 10b to expose the first conductive wire 33. Specific steps may include: providing a carrier plate 41, attaching the carrier plate 41 to the first surface 10a, and flipping it so that the second surface 10b faces upwards; then thinning and grinding the second surface 10b to expose the first conductive wire 33. The carrier plate 41 can be any suitable material, and a bonding process can be used to temporarily combine the carrier plate 41 and the first surface 10a to protect the first surface 10a and facilitate subsequent processes. In some embodiments, the depth of the through-hole 31 before thinning is greater than the depth of the annular trench 11. During the thinning and grinding of the second surface 10b, it can be ground to a first stop surface sufficient to connect the first conductive wire 33 as a grinding stop surface, and this first stop surface (e.g., ...) Figure 10 The first stopping surface 51 is spaced a certain distance from the annular groove 11 (magnetic core). In another embodiment, after grinding to the first stopping surface, grinding continues to the second stopping surface (e.g., ...). Figure 10 The first stop surface 52) and the second stop surface simultaneously expose the first conductor 33 and the annular groove 11 (or expose the annular groove 11 as close as possible to it). Of course, if the depth of the thinning through hole 31 is equal to the depth of the annular groove 11, the annular groove 11 can be exposed at the same time as the first stop surface exposes the first conductor 33.

[0062] Please refer to Figure 12Taking the thinned second surface 10b exposing the annular trench 11 as an example, a lead zirconate titanate film 22 is formed on the thinned second surface 10b to cover the annular trench 11 and the middle region 12 of the annular trench 11. The lead zirconate titanate film 22 on the thinned second surface 10b, together with the inner wall of the annular trench 11 and the lead zirconate titanate film 22 on the first surface 10a, constitutes a thin film structure that is closed in both the depth and surface directions of the substrate 10, serving as the magnetic core of the three-dimensional inductor, thereby improving the performance of the three-dimensional inductor. The specific formation steps may include, for example, forming a patterned third mask layer on the thinned second surface 10b to expose the annular trench 11 and the middle region 12 of the annular trench 11; then using a deposition process to form a lead zirconate titanate film 22 to cover the patterned third mask layer, the annular trench 11, and the surface of the middle region 12 of the annular trench 11; and then removing the patterned third mask layer and the lead zirconate titanate film 22 thereon. It should be noted that if the thinned second surface 10b does not expose the bottom of the annular groove 11, that is, the lead zirconate titanate film 22 formed in this step can only cover the projection of the middle region 12 on the second surface 10b. In other words, it is feasible for the lead zirconate titanate film 22 on the second surface 10b not to contact the lead zirconate titanate film 22 in the annular groove 11 to form a completely closed film structure; even omitting this step, that is, not forming the lead zirconate titanate film 22 on the thinned second surface 10b, is also feasible. Of course, in some embodiments, the lead zirconate titanate film 22 can also extend to cover the projection of the annular groove 11 on the thinned second surface 10b.

[0063] Please refer to Figure 13 A second dielectric layer 42 is formed on the thinned second surface 10b, and a second conductor 34 connecting the first conductor 33 is formed on the second dielectric layer 42. The material of the second dielectric layer 42 can be the same as that of the first dielectric layer 32, and the second conductor 34 is formed on the thinned second surface 10b using the same process as that used to form the second conductor 34 on the first surface 10a. The second conductor 34 on the first surface 10a and the second conductor 34 on the thinned second surface 10b are sequentially connected to the corresponding first conductor 33, thereby forming a coil (spiral coil) surrounding the annular groove 11 (magnetic core). The spiral coil extends into a strip shape (straight spiral coil).

[0064] It should be noted that other methods can also be used to form the second conductive line 34 on the first surface 10a and / or the thinned second surface 10b. For example, an adhesive layer and a seed layer can be formed sequentially on the first surface 10a and / or the thinned second surface 10b, then a patterning process can be performed on the adhesive layer and the seed layer, retaining the adhesive layer and the seed layer in the area for forming the second conductive line 34, and then a chemical electroplating process can be performed to form a metal layer in the area with the adhesive layer and the seed layer, thus forming the second conductive line 34.

[0065] Please refer to Figure 14a and Figure 14b Remove the carrier plate 41 to form the three-dimensional inductor of this embodiment. Figure 14a This is a cross-sectional schematic diagram of a three-dimensional inductor. Figure 14b This is a top view of a three-dimensional inductor.

[0066] In summary, this invention forms an annular trench on the first surface of a substrate, and a lead zirconate titanate thin film is formed on the inner wall of the annular trench to serve as the magnetic core of a three-dimensional inductor. A first material layer is then filled into the annular trench, and second wires are formed on the first and second surfaces respectively to connect to the first wires, forming a coil surrounding the magnetic core, thereby forming a three-dimensional inductor. The higher permeability of the lead zirconate titanate thin film compared to the substrate increases the inductance of the three-dimensional inductor. The higher dielectric constant of the lead zirconate titanate thin film compared to the substrate reduces eddy current losses, and the thinner film structure reduces core losses, thereby improving the quality factor. Furthermore, compared to using a solid structure (such as the substrate itself, air, or other materials) as the magnetic core, using a thin film structure formed by covering the inner wall of the annular trench with a lead zirconate titanate thin film as the magnetic core is not only easier to implement in terms of manufacturing process, but also simultaneously improves the inductance and quality factor of the three-dimensional inductor.

[0067] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for fabricating a three-dimensional inductor, characterized in that, include: A substrate is provided, the substrate having opposing first and second surfaces, wherein an annular trench is formed on the first surface; A lead zirconate titanate thin film is formed to cover the inner wall of the annular trench to form the magnetic core of the three-dimensional inductor, and a first material layer is formed to cover the lead zirconate titanate thin film and fill the annular trench. A plurality of through holes are formed to at least partially surround the annular trench, the depth of the through holes being greater than or equal to the depth of the annular trench, a first dielectric layer is formed to cover the inner wall of the through holes and the lead zirconate titanate film on the first surface, and a first conductive line is formed in the through holes; The substrate is thinned from the second surface to expose the first conductor, and a plurality of second conductors are formed on the second surface and the first surface respectively, which are sequentially connected to the corresponding first conductors. The first conductors and the second conductors surround the magnetic core as the coil of the three-dimensional inductor.

2. The method for fabricating a three-dimensional inductor according to claim 1, characterized in that, The steps for forming the magnetic core include: A patterned mask layer is formed to cover the first surface and expose the annular groove; A lead zirconate titanate thin film is formed using a deposition process to cover the patterned mask layer and the inner wall of the annular trench; Remove the patterned mask layer and use the lead zirconate titanate film within the annular trench as the magnetic core.

3. The method for fabricating a three-dimensional inductor according to claim 2, characterized in that, The patterned mask layer also exposes the central region of the annular trench, on which the lead zirconate titanate film is formed and retained as part of the magnetic core.

4. The method for fabricating a three-dimensional inductor according to claim 1, characterized in that, The material of the first material layer includes polyimide.

5. The method for fabricating a three-dimensional inductor according to claim 1, characterized in that, The depth of the via is less than the thickness of the substrate, and the step of forming the first wire within the via includes: A first dielectric layer is formed to cover the inner wall of the through hole and the surface of the first surface; An adhesion layer and a seed layer are sequentially formed on the first medium layer; A metal layer is formed on the seed layer using a chemical electroplating process, and the through-hole is filled to the top of the first surface; The grinding process is performed with the first dielectric layer as the grinding stop layer, and the metal layer and seed layer in the through hole are used as the first conductive line.

6. The method for fabricating a three-dimensional inductor according to claim 1, characterized in that, After the first conductor is formed, a plurality of second conductors are formed on the first surface to connect the plurality of first conductors.

7. The method for fabricating a three-dimensional inductor according to claim 6, characterized in that, After forming a plurality of second conductors on the first surface, the method further includes: A carrier plate is provided, the carrier plate is attached to the first side, and then flipped so that the second side is facing up; The second surface is thinned and ground until the first conductor is exposed.

8. The method for fabricating a three-dimensional inductor according to claim 7, characterized in that, The second surface is thinned and ground until the first conductor and the annular groove are exposed.

9. The method for fabricating a three-dimensional inductor according to claim 7 or 8, characterized in that, The lead zirconate titanate film is formed on the thinned second surface to cover the middle region of the annular groove or the projected region corresponding to the middle region of the annular groove.

10. The method for fabricating a three-dimensional inductor according to claim 1, characterized in that, The steps for forming the second conductor include: A second dielectric layer is formed to cover the surface of the substrate; The second dielectric layer is graphically represented to form several trenches that connect to the first conductor; A second conductor is formed within the trench, and the second conductor is connected to the first conductor.

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