Wiring structure

Abstract

To provide a passive element suitable for mobile front-end modules and a method for manufacturing the same.SOLUTION: A passive element 100 includes a board 101, a first wiring 102 on the board, a second wiring 106 on the first wiring, a first insulating film 104 located between the first wiring and the second wiring and in contact with the first wiring and the second wiring, and a protective film 110 on the second wiring. The protective film includes a first inorganic film 110a including silicon nitride, a second inorganic film 110b located on the first inorganic film, in contact with the first inorganic film, and including silicon oxide, and a third inorganic film 110c located on the second inorganic film, in contact with the second inorganic film, and including silicon nitride.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to passive elements suitable for mobile front-end modules and the like, as well as methods for making the same. [Background technology]

[0002] With the rapid spread of electronic devices with wireless communication functions, high frequency bands are being used in a great number of wireless communications. For this reason, various RF front-end modules have been developed to prevent interference during communication and ensure sufficient communication distance. RF front-end modules incorporate various passive elements for filtering in multi-band and multi-standard communications. For example, Non-Patent Document 1 shows that integrated passive elements such as 3D inductors intended for use in RF front-end modules can be formed on glass through-hole wiring substrates. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Takamasa Takano and 2 others, "3D IPD on Thur Glass Via Substrate using panel Manufacturing Technology," IMAPS 2017-50th International Symposium on Microelectronics, (USA), October 2017, p.000097-000102 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the objectives of the present disclosure is to provide a passive element suitable for a mobile front-end module or the like, and a method for manufacturing the same. [Means for solving the problem]

[0005] One embodiment of the present disclosure is a passive element. The passive element includes a substrate, a first wiring on the substrate, a second wiring on the first wiring, a first insulating film located between the first wiring and the second wiring and in contact with the first wiring and the second wiring, and a protective film on the second wiring. The protective film includes a first inorganic film containing silicon nitride, a second inorganic film located on the first inorganic film and in contact with the first inorganic film and containing silicon oxide, and a third inorganic film located on the second inorganic film and in contact with the second inorganic film and containing silicon nitride.

[0006] One embodiment of the present disclosure is a passive element. The passive element includes a substrate having a first surface and a second surface facing each other and a through hole, a first wiring overlapping the first surface, the second surface, and the sidewall of the through hole, a second wiring located on the first surface via the first wiring, a first insulating film located between the first wiring and the second wiring and in contact with the first wiring and the second wiring, and a protective film on the second wiring. The protective film includes a first inorganic film containing silicon nitride, a second inorganic film located on the first inorganic film and in contact with the first inorganic film, containing silicon oxide, and a third inorganic film located on the second inorganic film and in contact with the second inorganic film, containing silicon nitride. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view of a passive element according to an embodiment. [Diagram 2] FIG. 1 is a schematic cross-sectional view of a passive element according to an embodiment. [Diagram 3] FIG. 1 is a schematic cross-sectional view of a passive element according to an embodiment. [Figure 4] FIG. 1 is a schematic cross-sectional view of a passive element according to an embodiment. [Diagram 5] FIG. 1 is a schematic cross-sectional view of a passive element according to an embodiment. [Figure 6]1A to 1C are schematic cross-sectional views illustrating a method for fabricating a passive element according to an embodiment. [Figure 7] 1A to 1C are schematic cross-sectional views illustrating a method for fabricating a passive element according to an embodiment. [Figure 8] 1A to 1C are schematic cross-sectional views illustrating a method for fabricating a passive element according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, each embodiment of the present disclosure will be described with reference to the drawings, etc. However, the present disclosure can be implemented in various forms without departing from the spirit of the present disclosure, and should not be interpreted as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each drawing, elements having the same functions as those described in the previous drawings may be given the same reference numerals, and duplicated descriptions may be omitted.

[0010] In this specification and the claims, when describing an aspect in which a structure is placed on top of another structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of a structure so as to be in contact with the structure, and a case in which another structure is placed above a structure via yet another structure.

[0011] In this specification and claims, the expression "a structure is exposed from another structure" means an embodiment in which a part of a structure is not covered by another structure, and includes an embodiment in which the part not covered by the other structure is covered by yet another structure.

[0012] (First embodiment) In this embodiment, a passive element 100 according to one embodiment of the present disclosure will be described.

[0013] 1.Basic structure A cross-sectional schematic diagram of a passive element 100 is shown in FIG. 1. The passive element 100 has a substrate 101, a first wiring 102 located on the substrate 101, a first insulating film 104 located on the first wiring 102 and in contact with the first wiring 102, a second wiring 106 on the first insulating film 104, and a protective film 110 located on the second wiring 106. The first insulating film 104 is sandwiched between the first wiring 102 and the second wiring 106, and this structure forms a capacitive element 108. The protective film 110 covers a part of the first wiring 102, a part of the first insulating film 104, and a part of the second wiring 106. The protective film 110 has an opening that overlaps with the first wiring 102 and the second wiring 106, and an electrical connection to an external circuit (not shown) or the like is made through this opening. 1, the first wiring 102 and the protective film 110 may be in contact with the substrate 101. Although not shown, another wiring may be provided on the substrate 101. The first wiring 102 may also be electrically connected to another external circuit or the like.

[0014] The substrate 101 has a function of supporting the capacitor element 108, the protective film 110, and various wirings provided thereon. Examples of materials used for the substrate 101 include glass, silicon, gallium arsenide, gallium nitride, ceramics, and composite materials of glass and resin. Examples of resins include epoxy resin, polyimide, polyamide, and polyester. Although not shown, an undercoat in contact with the substrate 101 may be provided on the substrate 101. The undercoat is a film that has a function of preventing impurities such as metal ions from diffusing from the substrate 101 to the capacitor element 108 and the like, and contains, for example, silicon-containing inorganic compounds such as silicon oxide and silicon nitride. The undercoat may have a single layer structure or may be composed of multiple films containing different materials. When an undercoat is provided, the first wiring 102 and the protective film 110 are not in direct contact with the substrate 101, but are provided on the substrate 101 via the undercoat.

[0015] The first wiring 102 may include metals such as titanium, aluminum, copper, nickel, tungsten, molybdenum, gold, silver, iron, and chromium, or alloys thereof, and typically includes copper. The first wiring 102 may have a single layer structure, or may include multiple layers as shown in FIG. 1. As described below, the first wiring 102 may be formed by electrolytic plating, in which case the first wiring 102 may be configured to include a seed layer 102a as a first layer, and a second layer 102b located on the seed layer 102a and in contact with the seed layer 102a. The second layer 102b includes the metals and alloys described above. The seed layer 102a includes metals such as titanium, nickel, chromium, copper, and gold, or alloys thereof, and typically includes copper. The seed layer 102a and the second layer 102b may have the same composition.

[0016] Since the first insulating film 104 functions as a dielectric film for the capacitance element 108, it preferably contains a material with a high dielectric constant. Examples of high dielectric materials include silicon nitride, hafnium oxide, aluminum oxide, aluminum nitride, titanium oxide, barium titanate, and hafnium silicate, and silicon nitride is a typical material because of its ease of film formation. When silicon nitride is used, the first insulating film 104 can be formed by applying a chemical vapor deposition method (plasma CVD method) in the presence of plasma.

[0017] The second wiring 106 also includes a metal or alloy usable in the first wiring 102, and typically includes copper. Similarly to the first wiring 102, the second wiring 106 may also have a seed layer 106a as a first layer, and a second layer 106b located on the seed layer 106a and in contact with the seed layer 106a. The seed layer 106a and the second layer 106b include a metal usable in the seed layer 102a and the second layer 102b of the first wiring 102, respectively. When the seed layer 106a is not provided, the second layer 106b contacts the first insulating film 104.

[0018] Although not shown, the passive element 100 may further have a barrier layer between the seed layer 106a and the substrate 101 and / or between the seed layer 106a and the first insulating film 104. The material contained in the barrier layer is preferably a conductive material selected from metals such as titanium, tantalum, molybdenum, and tungsten, alloys thereof, or nitrides thereof, and has a higher melting point than the metals contained in the first wiring 102 and the second wiring 106. By providing the barrier layer, it is possible to prevent the metals contained in the first wiring 102 and the second wiring 106 from diffusing.

[0019] The structure of the protective film 110 can be selected arbitrarily, and can have, for example, a three-layer structure. When the protective film 110 has a three-layer structure, the protective film 110 is composed of a first inorganic film 110a, a second inorganic film 110b located on the first inorganic film 110a and in contact with the first inorganic film 110a, and a third inorganic film 110c located on the second inorganic film 110b and in contact with the second inorganic film 110b. The protective film 110 is provided so as to be in contact with the second wiring 106.

[0020] The dielectric constant of the second inorganic film 110b is preferably smaller than that of the first inorganic film 110a and the third inorganic film 110c. More specifically, the first inorganic film 110a and the third inorganic film 110c contain silicon nitride or silicon carbide. That is, the first inorganic film 110a and the third inorganic film 110c contain silicon and nitrogen or silicon and carbon as main constituent elements. On the other hand, the second inorganic film 110b contains silicon oxide or silicon oxynitride. That is, the second inorganic film 110b contains silicon and oxygen as constituent elements, and may further contain nitrogen. When nitrogen is contained, its composition is smaller than that of oxygen. These first inorganic film 110a, second inorganic film 110b, and third inorganic film 110c are formed by plasma CVD.

[0021] The third inorganic film 110c can be configured so that its thickness is greater than that of the first inorganic film 110a and less than that of the second inorganic film 110b. That is, the thicknesses of the first inorganic film 110a, the second inorganic film 110b, and the third inorganic film 110c can be respectively set to T 1 , T 2 , T 3 Then, the protective film 110 can be configured so that the following relationship holds: T 1 <T 3 <T 2

[0022] For example, the thickness of the first inorganic film 110a can be 0.05 μm to 0.3 μm, typically 0.2 μm. The thickness of the second inorganic film 110b can be 0.5 μm to 10 μm, or 1 μm to 5 μm. The thickness of the third inorganic film 110c can be 0.2 μm to 1 μm, or 0.3 μm to 0.7 μm, typically 0.5 μm.

[0023] The silicon oxide contained in the second inorganic film 110b is relatively hydrophilic. Therefore, if the third inorganic film 110c is not provided, impurities such as water will enter from the outside and diffuse into the first inorganic film 110a. Although the first inorganic film 110a contains silicon nitride, which has low hydrophilicity and high blocking properties against impurities, if the film is thin, some of the impurities will penetrate through it. For this reason, the surfaces of the first wiring 102 and the second wiring 106 are oxidized by water and the impurities contained therein, and as a result, the adhesion between the first wiring 102 and the first insulating film 104 and between the second wiring 106 and the first insulating film is reduced, and peeling occurs between them. When such peeling occurs, a leak current occurs, and the function of the capacitance element 108 is significantly reduced.

[0024] However, the passive element 100 may include a third inorganic film 110c, which has a thickness greater than that of the first inorganic film 110a and contains silicon nitride, on the second inorganic film 110b. In this configuration, the rate at which impurities penetrate into the first inorganic film 110a through the second inorganic film 110b can be significantly reduced, and as a result, peeling between the first wiring 102 and the first insulating film 104 and peeling between the first insulating film 104 and the second wiring 106 can be effectively prevented.

[0025] As described above, the protective film 110 does not necessarily have to have a three-layer structure, and may have a single-layer structure including the third inorganic film 110c when used in an atmosphere with a low moisture concentration, for example. In this case, the third inorganic film 110c is provided so as to contact the second wiring 106.

[0026] 2. Variations The above-mentioned structural features can be applied to various passive elements. Passive elements 120, 130, and 140 having a different structure from the passive element 100 will be described below as passive elements according to this embodiment.

[0027] 2A is different in structure from the passive element 100 in that it further includes a second insulating film 122 and a third wiring 124, and that an opening overlapping with the second wiring 106 is provided in the second insulating film 122, and the second wiring 106 and the third wiring 124 are electrically connected through this opening. The opening provided in the protective film 110 exposes the third wiring 124, and electrical connection with other external circuits and the like is made through this opening.

[0028] The second insulating film 122 is provided so that a part of it is sandwiched between the second wiring 106 and the protective film 110, and so as to embed the first wiring 102, the second wiring 106, and the first insulating film 104. That is, the second insulating film 122 is formed so as to be in contact with the upper surface of the first insulating film 104 and the upper surface of the second wiring 106.

[0029] The second insulating film 122 contains an organic compound. The organic compound used preferably has a low dielectric constant and a low dielectric loss tangent. For example, the dielectric constant is 2.0 or more and 4.0 or less, and the dielectric loss tangent is 1×10 -4 More than 1×10 -2 or less, or 1×10 -3 More than 1×10 -2 The following organic compounds can be used as the second insulating film 122. Such organic compounds are typically polymers (hereinafter simply referred to as polyimide) with a polyimide skeleton, and the polyimide may be chain-like or may be cross-linked between molecules. The second insulating film 122 may be mixed with epoxy resin, silicon oxide particles, glass fiber, or the like. The second insulating film 122 may be flexible.

[0030] The third wiring 124 includes a metal or alloy that can be used in the first wiring 102 or the second wiring 106. Like the first wiring 102 or the second wiring 106, the third wiring 124 may also have a multi-layer structure. For example, as shown in FIG. 2A, the third wiring 124 may include a seed layer 124a as a first layer and a second layer 124b located on the seed layer 124a and in contact with the seed layer 124a. The seed layer 124a and the second layer 124b can have the same configuration as the seed layers 102a and 106a and the second layers 102b and 106b of the first wiring 102 or the second wiring 106, respectively. Although not shown, a barrier layer may be provided between the seed layer 124a and the second wiring 106.

[0031] 2B, a part of the first insulating film 104 may be in contact with the side surface of the first wiring 102 or the upper surface of the substrate 101. When an undercoat is provided, the first insulating film 104 may be in contact with the undercoat.

[0032] 3 has a second insulating film 122 and is structured differently from the passive element 100 in that a second wiring 106 is disposed so as to cover at least a portion of the protective film 110. The second wiring 106 contacts the first insulating film 104 at an opening provided in the protective film 110 and the second insulating film 122.

[0033] The passive element 130 shown in FIG. 4 differs from the passive element 120 in that the upper-limit relationship between the third wiring 124 and the protective film 110 is different. More specifically, in the passive element 130, the third wiring 124 is located on the protective film 110 and contacts the protective film 110. Furthermore, the third wiring 124 contacts the second wiring 106 at an opening provided in the protective film 110. As an optional configuration, the passive element 130 may have a third insulating film 126 located on the third wiring 124 and contacting the third wiring 124. The third insulating film 126 also has an opening, through which the third wiring is exposed and connected to other wiring. The third insulating film 126 also contains an organic compound, and the organic compound may have the same composition as the organic compound contained in the second insulating film 122.

[0034] As described above, the second insulating film 122 and the third insulating film 126 contain an organic compound, and therefore have a thermal expansion coefficient of 50 ppm or more. In addition, the thermal expansion coefficient of the metals constituting the first wiring 102, the second wiring 106, and the third wiring 124 is also 10 ppm or more, so that stress remains in the first insulating film 104 due to heat treatment in the manufacturing process of the passive element. On the other hand, the thermal expansion coefficient of the first insulating film 104 is 0.1 ppm to 0.5 ppm, which is approximately the same as that of the protective film 110. Therefore, as in the structure shown in this embodiment, by disposing the protective film 110 on the second insulating film 122, the second wiring 106, or the third wiring 124, it is possible to reduce the residual stress in the first insulating film 104. As a result, peeling between the first insulating film 104 and the first wiring 102, and peeling between the first insulating film 104 and the second wiring 106 can be prevented, the occurrence of leakage current is suppressed, and a capacitor element 108 with stable characteristics can be obtained.

[0035] The passive element 140 shown in FIG. 5 is different in structure from the passive element 120 in that one or more through holes 142 are provided in the substrate 101, and the first wiring 102 covers a part of the upper surface (first surface) of the substrate 101, a part of the lower surface (second surface) opposite to the upper surface, and at least a part of the side wall of the through hole 142. The first wiring 102 functions as a through wiring that penetrates the substrate 101. In the through hole 142, not only the first wiring 102 but also a through electrode 144 is provided. As with the first wiring 102 and the second wiring 106, the through electrode 144 can also have a seed layer 144a as a first layer and a second layer 144b overlapping the seed layer 144a. The through hole 142 may further include a filler 146 containing an organic compound such as epoxy resin, acrylic resin, polyimide, polyamide, or polyester, or titanium or copper. When filling with an organic compound, an inorganic material such as silica may be mixed with the organic compound. Although not shown, the passive element 140 may be configured so that the through-hole 142 is filled with the second layer 102b of the first wiring 102 without disposing the filling material 146. Also, one or more layers of an insulating film containing an organic compound such as polyimide or polyamide, or an inorganic compound such as silicon oxide or silicon nitride may be provided between the seed layer 102a and the substrate 101. This insulating film also functions as an undercoat.

[0036] Furthermore, as an optional configuration, a second protective film 148 may be provided on the second surface of the substrate 101. The second protective film 148 may contain the same material as the second insulating film 122. When the second protective film 148 is provided, an opening that exposes the first wiring 102 and an opening that exposes a part of the through electrode 144 are provided in the second protective film 148.

[0037] By employing such a configuration, electrical connection between the passive element 140 and an external circuit or the like can be easily achieved.

[0038] In passive elements that require high operating frequencies, such as high frequency elements, the insulating film surrounding the wiring of the passive element is required to have a low dielectric constant and dielectric dissipation factor in order to prevent signal transmission loss and delay. Even if an insulating film (e.g., second insulating film 122 in passive element 100) is formed using a material that satisfies such performance requirements, impurities such as water, oxygen, and metal ions will penetrate into the insulating film from the outside after the passive element is formed, and the dielectric constant and dielectric dissipation factor of the insulating film will gradually increase. As a result, signal transmission loss and delay will occur, significantly affecting the characteristics of the passive element.

[0039] On the other hand, in the passive elements 120, 130, and 140, the upper surface of the second insulating film 122 covering the first wiring 102 and the second wiring 106 is covered by the protective film 110 having a three-layer structure. As described above, when the third inorganic film 110c does not exist, the silicon oxide contained in the second inorganic film 110b is relatively hydrophilic, so that when impurities such as water enter from the outside, the impurities diffuse into the first inorganic film 110a. When the thickness of the first inorganic film 110a is small, some of the impurities penetrate. Therefore, the impurities enter the second insulating film 122, and the dielectric constant and dielectric loss tangent of the second insulating film 122 increase.

[0040] However, as described above, since the protective film 110 is provided with the third inorganic film 110c having a relatively large thickness, it is possible to significantly reduce the rate at which impurities penetrate into the first inorganic film 110a and the second insulating film 122 via the second inorganic film 110b, and to suppress an increase in the dielectric constant and dielectric loss tangent of the second insulating film 122. This enables the passive element 100 to function as a high-frequency device that is driven at a high frequency.

[0041] Second embodiment In this embodiment, a method for manufacturing the passive element described in the first embodiment will be described by taking as an example a passive element 140. Descriptions of configurations that are the same as or similar to those described in the first embodiment may be omitted.

[0042] First, through holes 142 are formed in the substrate 101 (FIG. 6(A)). When a glass substrate is used as the substrate 101, the through holes 142 may be formed by etching such as plasma etching or wet etching, laser irradiation, or mechanical processing such as sandblasting or ultrasonic drilling. The number and size of the through holes 142 can be determined arbitrarily according to the design of the passive element 140. Then, seed layers 102a, 144a are formed so as to cover at least a part of the sidewall of the through hole 142 and a part of both sides (first surface, second surface) of the substrate 101. The seed layers 102a, 144a can be formed by a sputtering method, a CVD method, electroless plating, a vapor deposition method, or the like. In particular, the seed layers 102a, 144a can be formed efficiently by applying the sputtering method. Although not shown, before the formation of the seed layers 102a and 144a, one or more layers of an insulating film containing an organic compound such as polyimide or polyamide, or an inorganic compound such as silicon oxide or silicon nitride, may be formed on the side walls of the through hole 142 and on both sides of the substrate 101.

[0043] Next, a resist mask 150 for protecting regions where the first wiring 102 and the through electrode 144 are not to be formed is formed on the first and second surfaces of the substrate 101 (FIG. 6(A)). The resist mask 150 may be formed by applying and hardening a liquid resist, but since the substrate 101 has the through holes 142, the resist mask 150 can be efficiently formed by attaching a film-like resist to the first and second surfaces and then performing exposure and development.

[0044] Then, the seed layers 102a and 144a are supplied with electricity to perform electrolytic plating, and a metal film is formed on the seed layers 102a and 144a that are not covered by the resist mask 150, and the second layer 102b of the first wiring 102 and the second layer 144b of the through electrode 144 are formed. Then, the resist mask 150 is removed (FIG. 6(B)), and the seed layers 102a and 144b exposed from the second layers 102b and 144b are removed by etching, thereby forming the first wiring 102 and the through electrode 144 (FIG. 6(C)). As the etchant, an etchant containing an acid such as sulfuric acid can be used. Although not shown, other wirings may be formed on the first surface or the second surface of the substrate 101 prior to forming the through hole 142, the first wiring 102, and the through electrode 144.

[0045] Next, the inside of through-hole 142 is filled with filler 146 (FIG. 6(C)). For example, epoxy resin, acrylic resin, polyimide, or a precursor thereof is applied to fill through-hole 142 using an inkjet method, a printing method, a spin-coating method, or the like, and then cured to form filler 146.

[0046] Subsequently, the first insulating film 104 is formed on the first wiring 102 (FIG. 6(D)). As described above, the first insulating film 104 typically contains silicon nitride and can be formed by applying a plasma CVD method. Thereafter, the seed layer 106a is formed so as to cover the through electrode 144, the filling material 146, the first wiring 102, and the first insulating film 104 (FIG. 6(D)). Although not shown, a barrier layer may be formed before forming the seed layer 106a. In this case, for example, the barrier layer containing titanium can be formed to a thickness of 0.1 μm, and the seed layer 106a containing copper can be formed to a thickness of 0.2 μm. The seed layer 106a and the barrier layer are formed by using a CVD method, a sputtering method, an electroless plating method, a vapor deposition method, or the like.

[0047] Next, a resist mask 152 is formed in an area where the second wiring 106 is not to be formed, and power is supplied to the seed layer 106a to form the second layer 106b of the second wiring 106 by electrolytic plating (FIG. 7(A)). Thereafter, the resist mask 152 is removed, and the seed layer 106a exposed from the second layer 106b is removed by etching (FIG. 7(B)).

[0048] Subsequently, a second insulating film 122 is formed so as to cover the first wiring 102, the first insulating film 104, and a part of the second wiring 106 (FIG. 7(C)). Specifically, a photosensitive polymer such as polyimide described in the first embodiment or a solution or suspension of its precursor is applied onto the substrate 101, and then exposure using a photomask, development, and baking are performed to form the second insulating film 122 having an opening that exposes the second wiring 106. Alternatively, the second insulating film 122 may be formed by attaching a film of the above polymer and performing exposure using a photomask, development, and baking. The thickness of the second insulating film 122 is appropriately adjusted within the range of 0.5 μm to 5 μm.

[0049] Thereafter, the second layer 124b is formed via the seed layer 124a by a method similar to that for forming the seed layer 106a and the second layer 106b, thereby forming the third wiring 124 (FIG. 8(A)).

[0050] Subsequently, the protective film 110 is formed. The protective film 110 is formed by sequentially forming a first inorganic film 110a, a second inorganic film 110b, and a third inorganic film 110c using a plasma CVD method (FIG. 8(B)). Thereafter, plasma etching is performed on the protective film 110 to form an opening that overlaps with the third wiring 124. As a result, a part of the third wiring 124 is exposed from the protective film 110 (FIG. 8(C)). The plasma etching is performed using, for example, CF 4 or CHF 4 Fluorine-containing alkanes or alkenes such as the above may be used. EXAMPLES

[0051] In this example, the results of a reliability test performed on the passive element of the first embodiment will be described. The passive element used was the passive element 140 (see FIG. 5), and the seed layer 102a was formed to a thickness of 0.1 μm using an electroless plating method. The first insulating film 104 had a thickness of 0.1 μm. A barrier layer (thickness 0.1 μm) containing titanium and a seed layer 106a (thickness 0.2 μm) containing copper were formed on the first insulating film 104 using a sputtering method. Similarly, a barrier layer (thickness 0.1 μm) containing titanium and a seed layer 124a (thickness 0.2 μm) containing copper were formed on the second wiring 106. The first inorganic film 110a, the second inorganic film 110b, and the third inorganic film 110c of the protective film 110 were all formed by a plasma CVD method, and their thicknesses were 0.2 μm, 1.0 μm, and 0.4 μm, respectively.

[0052] The fabricated passive element was left to stand for 96 hours under conditions of a temperature of 130°C and a humidity of 85%, and then the cross section was observed using a scanning electron microscope. As a result, no peeling was observed between the first wiring 102 and the first insulating film 104, and between the second wiring 106 and the first insulating film 104. As a result of measuring the capacitance of the capacitive element 108 formed by the first wiring 102, the first insulating film 104, and the second wiring 106, it was confirmed that a capacitance value almost identical to the design value was obtained.

[0053] In contrast, when a passive element having the same structure as the passive element 140 but not having the protective film 110 was used as a comparative example, it was found that peeling occurred between the first wiring 102 and the first insulating film 104, and between the second wiring 106 and the first insulating film 104. It was also confirmed that the first wiring 102 and the second wiring 106 were oxidized. As a result of measuring the capacitance of the capacitor 108, the leakage current was very large, and the capacitance value could not be obtained.

[0054] As shown in the above examples, it has been confirmed that by using the protective film 110 having a three-layer structure, it is possible to provide a highly reliable passive element.

[0055] The above-described embodiments of the present disclosure may be combined as appropriate as long as they are not mutually inconsistent. In addition, a product in which a person skilled in the art appropriately adds or deletes components or modifies the design based on each embodiment is also included in the scope of the present disclosure as long as it includes the gist of the present disclosure.

[0056] Furthermore, even if there are other effects and advantages different from those brought about by the above-described embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present disclosure. [Explanation of symbols]

[0057] 100: passive element, 101: substrate, 102: first wiring, 102a: seed layer, 102b: second layer, 104: first insulating film, 106: second wiring, 106a: seed layer, 106b: second layer, 108: capacitance element, 110: protective film, 110a: first inorganic film, 110b: second inorganic film, 110c: third inorganic film, 120: passive element, 122: third inorganic film, No. 2 insulating film, 124: third wiring, 124a: seed layer, 124b: second layer, 126: third insulating film, 128: passive element, 130: passive element, 140: passive element, 142: through hole, 144: through electrode, 144a: seed layer, 144b: second layer, 146: filling material, 148: second protective film, 150: resist mask, 152: resist mask,

Claims

1. A first wiring a second wiring on the first wiring; a first insulating film located between the first wiring and the second wiring and in contact with the first wiring and the second wiring; and a protective film on the second wiring; The protective film is a first inorganic film comprising silicon nitride; a second inorganic film located on and in contact with the first inorganic film, the second inorganic film including silicon oxide; and a third inorganic film located on and in contact with the second inorganic film, the third inorganic film comprising silicon nitride; A wiring structure, wherein a thickness of the third inorganic film is greater than a thickness of the first inorganic film and less than a thickness of the second inorganic film.

2. a substrate having a first surface and a second surface opposed to each other and having a through hole; a first wiring overlapping the first surface, the second surface, and a sidewall of the through hole; a second wiring located on the first surface via the first wiring; a first insulating film located between the first wiring and the second wiring and in contact with the first wiring and the second wiring; and a protective film on the second wiring; The protective film is a first inorganic film comprising silicon nitride; a second inorganic film located on and in contact with the first inorganic film, the second inorganic film including silicon oxide; and a third inorganic film located on and in contact with the second inorganic film, the third inorganic film comprising silicon nitride; A wiring structure, wherein a thickness of the third inorganic film is greater than a thickness of the first inorganic film and less than a thickness of the second inorganic film.

3. The wiring structure according to claim 1 , wherein the first inorganic film is in contact with an upper surface of the second wiring.

4. The first wiring and the second wiring each include a first layer comprising a metal selected from titanium, chromium, nickel, copper, and gold; and 3. The wiring structure of claim 1, further comprising a second layer overlying the first layer and comprising a metal selected from titanium, aluminum, copper, nickel, tungsten, molybdenum, gold, silver, iron, and chromium.

5. At least one of the first wiring and the second wiring further includes a third layer located below the first layer, in contact with the first layer, and including a metal selected from titanium, tantalum, molybdenum, and tungsten; 5. The wiring structure of claim 4, wherein the metal contained in the third layer has a higher melting point than the metal contained in the second layer.

6. 3. The wiring structure according to claim 1, further comprising a third wiring located between said second wiring and said protective film and in contact with said second wiring and said protective film.

7. the protective film has an opening overlapping the second wiring, 3. The wiring structure according to claim 1, further comprising a third wiring located on said protective film, in contact with said protective film, and in contact with said second wiring in said opening.

8. 8. The wiring structure according to claim 7, further comprising a second insulating film containing an organic compound, the second insulating film being located on the third wiring and the protective film.

9. The wiring structure according to claim 1 , wherein the first insulating film is in contact with a side surface of the first wiring.

10. 3. The wiring structure according to claim 1, wherein the first insulating film comprises silicon nitride.

11. A filler is provided in the through hole, The wiring structure according to claim 2 , wherein the filler includes a metal or a resin.

12. The wiring structure according to claim 2 , wherein the first insulating film contacts an upper surface of the substrate.

13. a substrate having a first surface and a second surface opposed to each other and having a through hole; The wiring structure of claim 1 , wherein the first wiring overlaps the first surface, the second surface, and a sidewall of the through hole.

14. The wiring structure according to claim 13 , further comprising a second protective film covering a portion of the first wiring under the substrate.

15. The wiring structure according to claim 13 , further comprising a filler material in the through hole in contact with the first wiring.

16. The wiring structure according to claim 2 , further comprising a second protective film covering a portion of the first wiring under the substrate.

17. The wiring structure according to claim 2 , further comprising a filler material in contact with the first wiring in the through hole.

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