Isolator

Abstract

To provide an isolator capable of improving reliability.SOLUTION: An isolator according to an embodiment, comprises a first electrode, a second electrode, a first insulation part, an insulation layer, a first insulation layer, a conductor, and an insulation part. The first insulation part is provided between the first electrode and the second electrode. A part of the first insulation part is positioned around the second electrode along a first surface that is vertical to a first direction directed to the second electrode from the first electrode. The insulation layer is provided around the second electrode along the first surface, is positioned on the first insulation part, and is made of silicon nitride. The first insulation layer is provided on the second electrode, contains silicon, carbon, and nitrogen, and is contacted to an upper surface of the second electrode. The conductor is provided around the first electrode and the second electrode along the first surface. The insulation part is provided between the second electrode and the conductor, is positioned between the insulation layer and the first insulation layer in the first direction, and is made of silicon oxide.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention relates to an isolator. [Background technology]

[0002] An isolator transmits signals by utilizing changes in a magnetic or electric field while blocking current, and there is a demand for improved reliability of this isolator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2018 / 0286802 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an isolator capable of improving reliability. [Means for solving the problem]

[0005] The isolator according to the embodiment includes a first electrode, a second electrode, a first insulating portion, an insulating layer, a conductor, and an insulating portion. The second electrode is provided on the first electrode and is spaced apart from the first electrode. The first insulating portion is provided between the first electrode and the second electrode. A part of the first insulating portion is located around the second electrode along a first surface perpendicular to a first direction from the first electrode to the second electrode. The insulating layer is provided around the second electrode along the first surface, located on the first insulating portion, and made of silicon nitride. The first insulating layer is provided on the second electrode, contains silicon, carbon, and nitrogen, and is in contact with an upper surface of the second electrode. The conductor is provided around the first electrode and the second electrode along the first surface. The insulating portion is provided between the second electrode and the conductor, located between the insulating layer and the first insulating layer in the first direction, and made of silicon oxide. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view illustrating an isolator according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Diagram 3] 2A to 2C are schematic diagrams illustrating characteristics of the isolator according to the first embodiment. [Figure 4] 1 is a cross-sectional view showing a part of an isolator according to a reference example, and a graph showing analysis results of the isolator according to the reference example. [Diagram 5] 1A and 1B are a cross-sectional view illustrating a portion of an isolator according to a first embodiment, and graphs illustrating analysis results of the isolator according to the embodiment. [Figure 6] FIG. 4 is a cross-sectional view illustrating an isolator according to a modified example of the first embodiment. [Figure 7] FIG. 4 is a cross-sectional view illustrating an isolator according to a modified example of the first embodiment. [Figure 8] FIG. 4 is a cross-sectional view illustrating an isolator according to a modified example of the first embodiment. [Figure 9] FIG. 4 is a cross-sectional view illustrating an isolator according to a modified example of the first embodiment. [Figure 10] FIG. 11 is a plan view illustrating an isolator according to a second embodiment. [Figure 11] 6 is a schematic diagram illustrating a cross-sectional structure of an isolator according to a second embodiment. FIG. [Figure 12] FIG. 11 is a plan view illustrating an isolator according to a first modified example of the second embodiment. [Figure 13] FIG. 13 is a cross-sectional view taken along line XIII-XIII of FIG. [Figure 14] 14 is a cross-sectional view taken along the line XIV-XIV of FIG. 12. [Figure 15] FIG. 13 is a schematic diagram illustrating a cross-sectional structure of an isolator according to a first modified example of the second embodiment. [Figure 16] FIG. 11 is a plan view illustrating an isolator according to a second modified example of the second embodiment. [Figure 17] FIG. 13 is a schematic diagram illustrating a cross-sectional structure of an isolator according to a second modified example of the second embodiment. [Figure 18] FIG. 13 is a schematic diagram illustrating an isolator according to a third modified example of the second embodiment. [Figure 19] FIG. 11 is a perspective view illustrating a package according to a third embodiment. [Figure 20] FIG. 13 is a schematic diagram illustrating a cross-sectional structure of a package according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those already explained are given the same reference numerals and detailed explanations are omitted as appropriate.

[0008] (First embodiment) Fig. 1 is a plan view showing an isolator according to a first embodiment, and Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1. The isolator according to the first embodiment relates to a device called a digital isolator, a galvanic isolator, a galvanic isolation element, or the like.

[0009] 1 and 2, the isolator 100 according to the first embodiment includes a first circuit 1, a second circuit 2, a substrate 5, a first electrode 11, a second electrode 12, a first insulating layer 21, a second insulating layer 22, a third insulating layer 23, a fourth insulating layer 24, insulating layers 25 and 26, a first insulating section 31, insulating sections 30, 33, 35, 37, and 39, and a conductor 50. In Fig. 1, the first insulating layer 21, the second insulating layer 22, and the insulating sections 35, 37, and 39 are omitted.

[0010] In the description of the embodiment, an XYZ Cartesian coordinate system is used. The direction from the first electrode 11 to the second electrode 12 is defined as the Z direction (first direction). Two directions that are perpendicular to the Z direction and perpendicular to each other are defined as the X direction (second direction) and the Y direction (third direction). For the sake of description, the direction from the first electrode 11 to the second electrode 12 is referred to as "up" and the opposite direction is referred to as "down". These directions are based on the relative positional relationship between the first electrode 11 and the second electrode 12 and are unrelated to the direction of gravity.

[0011] 2, the insulating section 30 is provided on the substrate 5. The first electrode 11 is provided in the insulating section 30. The first insulating section 31 is provided on the first electrode 11. The second electrode 12 is provided on the first insulating section 31 and is separated from the first electrode 11. The second electrode 12 is electrically isolated from the first electrode 11.

[0012] 1 and 2, the first electrode 11 and the second electrode 12 are coils spirally arranged along the XY plane (first plane). The first electrode 11 and the second electrode 12 face each other in the Z direction. At least a portion of the second electrode 12 is aligned with at least a portion of the first electrode 11 in the Z direction.

[0013] The conductor 50 is provided around the first electrode 11 and the second electrode 12 along the XY plane. Specifically, the conductor 50 includes a first conductive portion 51, a second conductive portion 52, and a third conductive portion 53. The first conductive portion 51 is provided around the first electrode 11 along the XY plane. The second conductive portion 52 is provided on a part of the first conductive portion 51. A plurality of second conductive portions 52 are provided along the first conductive portion 51. The third conductive portion 53 is provided on the plurality of second conductive portions 52. The third conductive portion 53 is located around the second electrode 12 along the XY plane.

[0014] For example, a distance D1 between the second electrode 12 and the conductor 50 in the X direction is longer than a distance D2 between the first electrode 11 and the second electrode 12 in the Z direction.

[0015] The first insulating layer 21 is provided on the second electrode 12. For example, the first insulating layer 21 is in contact with the second electrode 12. The second insulating layer 22 is provided on the third conductive portion 53. For example, the second insulating layer 22 is in contact with the third conductive portion 53. The second insulating layer 22 is provided continuously with the first insulating layer 21. That is, one insulating layer provided on the second electrode 12 and the conductor 50 may function as the first insulating layer 21 and the second insulating layer 22. Alternatively, the second insulating layer 22 may be provided apart from the first insulating layer 21 and around the second insulating layer 22 along the XY plane.

[0016] The third insulating layer 23 is provided between the first electrode 11 and the first insulating portion 31. For example, the third insulating layer 23 is in contact with the first electrode 11. The fourth insulating layer 24 is provided around the bottom of the second conductive portion 52 along the XY plane. For example, the fourth insulating layer 24 is in contact with another part of the first conductive portion 51 and the second conductive portion 52. The fourth insulating layer 24 is provided continuously with the third insulating layer 23. Alternatively, the fourth insulating layer 24 may be separated from the third insulating layer 23 and provided around the third insulating layer 23 along the XY plane.

[0017] The insulating layer 25 is provided around the bottom of the second electrode 12 along the XY plane. The insulating layer 26 is provided around the bottom of the third conductive portion 53. The insulating layer 26 is provided continuously with the insulating layer 25. Alternatively, the insulating layer 26 may be separated from the insulating layer 25 and provided around the insulating layer 25 along the XY plane. The insulating portion 33 is provided on the insulating layers 25 and 26. The insulating portion 33 is located around the second electrode 12 and around the third conductive portion 53 along the XY plane.

[0018] 1, one end of the first electrode 11 (one end of the coil) is electrically connected to the first circuit 1 via a wiring 60. The other end of the first electrode 11 (the other end of the coil) is electrically connected to the first circuit 1 via a wiring 61.

[0019] One end of the second electrode 12 (one end of the coil) is electrically connected to the pad 62. One end of the wiring 63 is joined to the pad 62. One end of the second electrode 12 is electrically connected to the second circuit 2 via the pad 62 and the wiring 63.

[0020] The other end of the second electrode 12 (the other end of the coil) is electrically connected to the pad 64. One end of the wiring 65 is joined to the pad 64. The other end of the second electrode 12 is electrically connected to the second circuit 2 via the pad 64 and the wiring 65.

[0021] For example, the pad 62 is provided on one end of the second electrode 12. The pad 64 is provided on the other end of the second electrode 12. Alternatively, the position of the pad 62 in the Z direction and the position of the pad 64 in the Z direction may be the same as the position of the second electrode 12 in the Z direction. The pads 62 and 64 may be formed integrally with the second electrode 12.

[0022] As shown in FIG. 2, a pad 66 is provided on the conductor 50. The conductor 50 is electrically connected to a conductive member (not shown) via the pad 66 and the wiring 67. For example, the conductor 50 and the substrate 5 are connected to a reference potential. The reference potential is, for example, a ground potential. This can prevent the conductor 50 from becoming a floating potential. The possibility of unexpected insulation breakdown occurring between the conductor 50 and each electrode due to fluctuations in the potential of the conductor 50 can be reduced. The first circuit 1 may also be provided on the substrate 5. In this case, by providing the conductor 50 on the first circuit 1, the first circuit 1 is shielded by the conductor 50 against electromagnetic waves directed from the outside of the substrate 5 and the conductor 50 toward the first circuit 1. As a result, the operation of the first circuit 1 can be more stabilized.

[0023] An insulating portion 35 is provided along the XY plane around the pads 62 and 66. An insulating portion 37 is provided on the insulating portion 35. An insulating portion 39 is provided on the insulating portion 37. The pads 62, 64, and 66 are not covered by the insulating portions 35, 37, and 39, and are exposed to the outside.

[0024] One of the first circuit 1 and the second circuit 2 is used as a receiving circuit. The other of the first circuit 1 and the second circuit 2 is used as a transmitting circuit. Here, a case will be described in which the first circuit 1 is a receiving circuit and the second circuit 2 is a transmitting circuit.

[0025] The second circuit 2 sends a signal (current) with a waveform suitable for transmission to the first electrode 11. When the current flows through the first electrode 11, a magnetic field is generated that passes through the inside of the spiral first electrode 11. At least a part of the first electrode 11 is aligned with at least a part of the second electrode 12 in the Z direction. A part of the generated magnetic field lines passes through the inside of the second electrode 12. Due to a change in the magnetic field inside the second electrode 12, an induced electromotive force is generated in the second electrode 12, and a current flows through the second electrode 12. The first circuit 1 detects the current flowing through the second electrode 12 and generates a signal according to the detection result. As a result, the signal is transmitted between the first electrode 11 and the second electrode 12 in a state where the current is blocked (insulated).

[0026] An example of the material of each component of the isolator 100 will be described. The substrate 5 is, for example, a silicon substrate. The substrate 5 is, for example, doped with an impurity and has electrical conductivity. The first electrode 11, the second electrode 12, the conductor 50, the pad 62, the pad 64, and the pad 66 contain a metal. For example, the first electrode 11, the second electrode 12, the conductor 50, the pad 62, the pad 64, and the pad 66 contain a metal selected from the group consisting of copper and aluminum. In order to suppress heat generation in the first electrode 11 and the second electrode 12 when transmitting a signal, it is preferable that the electrical resistance of these components is low. From the viewpoint of reducing the electrical resistance, it is preferable that the first electrode 11, the second electrode 12, the conductor 50, the pad 62, the pad 64, and the pad 66 contain copper. The insulating portion 30, the first insulating portion 31, the insulating portion 33, and the insulating portion 35 contain silicon and oxygen. For example, the insulating portion 30, the first insulating portion 31, the insulating portion 33, and the insulating portion 35 contain silicon oxide. The insulating portion 30, the first insulating portion 31, the insulating portion 33, and the insulating portion 35 may further contain nitrogen. The insulating portion 37 contains silicon and nitrogen. For example, the insulating portion 37 contains silicon nitride. The insulating portion 39 contains an insulating resin such as polyimide or polyamide. The wires 63, 65, and 67 include a metal such as aluminum.

[0027] The first insulating layer 21 and the second insulating layer 22 contain silicon, carbon, and nitrogen. The first insulating layer 21 and the second insulating layer 22 may further contain hydrogen. The third insulating layer 23, the fourth insulating layer 24, the insulating layer 25, and the insulating layer 26 contain silicon and nitrogen. For example, the third insulating layer 23, the fourth insulating layer 24, the insulating layer 25, and the insulating layer 26 contain silicon nitride. By providing the first insulating layer 21 to the fourth insulating layer 24, it is possible to suppress the diffusion of the metal material contained in the first electrode 11, the second electrode 12, and the conductor 50 to each insulating portion. In addition, by providing the third insulating layer 23, it is possible to reduce the leakage current between the first electrode 11 and the second electrode 12.

[0028] The first electrode 11 may include metal layers 11a and 11b. The metal layer 11b is provided between the metal layer 11a and the insulating portion 30. The second electrode 12 may include metal layers 12a and 12b. The metal layer 12b is provided between the metal layer 12a and the first insulating portion 31, between the metal layer 12a and the insulating layer 25, and between the metal layer 12a and the insulating portion 33. The metal layers 11a and 12a include copper. The metal layers 11b and 12b include tantalum. The metal layers 11b and 12b may include a laminated film of tantalum and tantalum nitride. By providing the metal layers 11b and 12b, it is possible to suppress the diffusion of the metal material included in the metal layers 11a and 12a into each insulating portion.

[0029] The first conductive section 51 may include metal layers 51a and 51b. The metal layer 51b is provided between the metal layer 51a and the insulating section 30. The second conductive section 52 may include metal layers 52a and 52b. The metal layer 52b is provided between the metal layer 52a and the first insulating section 31, between the metal layer 52a and the fourth insulating layer 24, and between the metal layer 52a and the first conductive section 51. The third conductive section 53 may include metal layers 53a and 53b. The metal layer 53b is provided between the metal layer 53a and the first insulating section 31, between the metal layer 53a and the insulating layer 26, between the metal layer 53a and the insulating section 33, and between the metal layer 53a and the second conductive section 52. The metal layers 51a to 53a contain copper. The metal layers 51b to 53b contain tantalum. The metal layers 51b to 53b may include a laminated film of tantalum and tantalum nitride. By providing the metal layers 51b to 53b, it is possible to suppress diffusion of the metal material contained in the metal layers 51a to 53a into each insulating portion.

[0030] The effects of the first embodiment will be described. FIG. 3 is a schematic diagram illustrating the characteristics of the isolator according to the first embodiment. 3 shows equipotential lines EP in the vicinity of the outer periphery of the second electrode 12. In the isolator 100, when a signal is transmitted between the first electrode 11 and the second electrode 12, a positive voltage is applied to the second electrode 12 with respect to the first electrode 11 and the conductor 50. As shown in FIG 3, a potential gradient from the second electrode 12 to the first electrode 11 and a potential gradient from the second electrode 12 to the conductor 50 are generated.

[0031] Fig. 4(a) is a cross-sectional view showing a part of the isolator according to the reference example, and Fig. 4(b) is a graph showing the analysis results of the isolator according to the reference example. Fig. 5(a) is a cross-sectional view showing a part of the isolator according to the first embodiment, and Fig. 5(b) is a graph showing the analysis results of the isolator according to the first embodiment. 4(a), in the isolator 100r according to the reference example, insulating layers 21r and 22r are provided instead of the first insulating layer 21 and the second insulating layer 22, respectively. The insulating layers 21r and 22r contain nitrogen and silicon. The insulating layers 21r and 22r are formed without adding carbon and do not substantially contain carbon.

[0032] 4(b) and 5(b) show the results of elemental analysis on the dashed line L shown in FIG. 4(a) and FIG. 5(a), respectively. Secondary ion mass spectrometry (SIMS) was used for the analysis. The dashed line L is located midway in the X direction between the second electrode 12 and the third conductive portion 53. In FIG. 4(b) and FIG. 5(b), the vertical axis represents the position P in the Z direction. The horizontal axis represents the concentration C of copper element at each position in the Z direction. The concentration C is expressed in arbitrary units.

[0033] Conventionally, silicon nitride is used as a barrier layer or a passivation layer to prevent unintended diffusion or intrusion of elements. Nevertheless, the inventors discovered that the concentration of copper elements is high near the insulating layer 21r between the second electrode 12 and the third conductive portion 53, as shown in FIG. 4(b). Specifically, a peak in the concentration of copper elements was confirmed at the interface between the insulating portion 33 and the insulating layer 21r. Copper elements were also detected in the insulating portion 33, and the concentration decreased with increasing distance from the interface.

[0034] In the isolator, a high voltage of, for example, 0.6 kVrms or more is applied between the first electrode 11 and the second electrode 12 during signal transmission. At this time, as shown in FIG. 3, a large gradient of potential occurs not only between the first electrode 11 and the second electrode 12 but also between the conductor 50 and the second electrode 12. In the isolator 100r, it is considered that the metal contained in the second electrode 12 moves toward the conductor 50 along the interface between the second electrode 12 and the insulating layer 21r due to this gradient. Furthermore, it is considered that the metal that moves toward the conductor 50 diffuses into the insulating part 33 between the second electrode 12 and the conductor 50. When the metal diffuses from the second electrode 12 toward the conductor 50, a large leak current flows locally along the diffused metal, and dielectric breakdown may occur between the second electrode 12 and the conductor 50. For this reason, in order to reduce the possibility of dielectric breakdown, it is preferable to be able to suppress the diffusion of the metal from the second electrode 12.

[0035] In the isolator 100 according to the first embodiment, the first insulating layer 21 contains silicon, carbon, and nitrogen. The inventors discovered that when the first insulating layer 21 contains these materials, the diffusion of metal in the second electrode 12 is suppressed as shown in FIG. 5(b) compared to when carbon is not added to the first insulating layer 21. Specifically, a high concentration of metal element as shown in FIG. 4(b) was not confirmed between the second electrode 12 and the conductor 50. By suppressing the diffusion of metal from the second electrode 12, the possibility of dielectric breakdown occurring in the isolator 100 can be reduced. In addition, the total operating time (insulation life) of the isolator 100 until dielectric breakdown occurs can be extended. This improves the reliability of the isolator 100.

[0036] The reason why diffusion of metal from the second electrode 12 is suppressed when the first insulating layer 21 contains silicon, carbon, and nitrogen is believed to be as follows. In the insulating layer 21r to which no carbon is added, dangling bonds of silicon exist at the interface. Since silicon is relatively active, the metal of the second electrode 12 reacts with silicon. The metal reacted with silicon moves toward the conductor 50 along the interface of the insulating layer 21r due to the potential difference between the second electrode 12 and the conductor 50. On the other hand, in the first insulating layer 21 containing silicon, carbon, and nitrogen, carbon is present in the places where dangling bonds existed in the insulating layer 21r, and silicon is bonded to carbon. That is, the number of dangling bonds of silicon is smaller in the first insulating layer 21 than in the insulating layer 21r. This suppresses the reaction between silicon and the metal of the second electrode 12. As a result, even if a potential difference occurs between the second electrode 12 and the conductor 50, the metal does not move toward the conductor 50.

[0037] In order to suppress unintended diffusion of the metal contained in the conductor 50 (third conductive portion 53), it is preferable that the second insulating layer 22 is provided on the conductor 50. Like the first insulating layer 21, when the second insulating layer 22 contains silicon, carbon, and nitrogen, diffusion of the metal in the conductor 50 is suppressed more than in the insulating layer 22r.

[0038] In order to effectively suppress metal diffusion, the carbon concentration in first insulating layer 21 and second insulating layer 22 is preferably 10 mass % or more and 45 mass % or less.

[0039] In order to reduce the leakage current between the second electrode 12 and the conductor 50, it is preferable that the electrical resistance of the first insulating layer 21 and the second insulating layer 22 is higher. In order to increase the electrical resistance, the silicon concentration C1 Si Nitrogen concentration C1 (mass%) N (mass%) ratio C1 N / C1 Si In the second insulating layer 22, the silicon concentration (mass%) C2 is preferably 0.2 or more and 0.8 or less. Si Nitrogen concentration C2 N (mass%) ratio C2 N / C2 Si is preferably 0.2 or more and 0.8 or less.

[0040] First insulating layer 21 may further contain hydrogen. In this case, the hydrogen concentration in first insulating layer 21 is preferably 0.5 mass % or more and 5 mass % or less. Similarly, second insulating layer 22 may further contain hydrogen. In this case, the hydrogen concentration in second insulating layer 22 is preferably 0.5 mass % or more and 5 mass % or less.

[0041] (Modification) 6 to 9 are cross-sectional views illustrating an isolator according to a modification of the first embodiment. 6, the second insulating layer 22 is separated from the first insulating layer 21 along the XY plane. The first insulating layer 21 is provided at least on the second electrode 12. The second insulating layer 22 is provided at least on the third conductive portion 53. Even in this case, similar to the isolator 100, the diffusion of the metal contained in the second electrode 12 can be suppressed.

[0042] 7, the fourth insulating layer 24 contains silicon, carbon, and nitrogen. The fourth insulating layer 24 may further contain hydrogen. When a current flows through the first electrode 11 and the second electrode 12, heat is generated. When the first electrode 11, the second electrode 12, and the conductor 50 thermally expand, stress is applied to each of the adjacent insulating layers and insulating portions.

[0043] The Young's modulus of silicon nitride is higher than that of silicon oxide. That is, silicon nitride is less likely to deform than silicon oxide. When the fourth insulating layer 24 contains silicon and nitrogen, a large stress is applied to the fourth insulating layer 24 at the contact portion CP between the bottom surface of the second conductive portion 52 and the fourth insulating layer 24, and the fourth insulating layer 24 may peel off or be damaged. In addition, the thermal expansion amount of a metal layer containing tantalum is larger than that of a metal layer containing copper or aluminum. Therefore, the thermal expansion amount of the metal layer 52b along the XY plane is particularly large at the bottom of the second conductive portion 52. In this case, the possibility of peeling off or being damaged at the contact portion CP is further increased.

[0044] The Young's modulus of the fourth insulating layer 24 when it contains silicon, carbon, and nitrogen is lower than the Young's modulus of the fourth insulating layer 24 when it contains silicon and nitrogen. That is, the addition of carbon makes the fourth insulating layer 24 more easily deformable. According to the isolator 120, peeling or damage caused by stress on the fourth insulating layer 24 during thermal expansion is suppressed at the contact portion CP. This improves the reliability of the isolator 120.

[0045] Furthermore, the third insulating layer 23 may contain silicon, carbon, and nitrogen. The third insulating layer 23 may further contain hydrogen. One insulating layer containing silicon, carbon, and nitrogen may be provided on the first electrode 11 and around the bottom of the second conductive portion 52, and this one insulating layer may be used as the third insulating layer 23 and the fourth insulating layer 24.

[0046] According to the inventors' verification, even when carbon is not added to the third insulating layer 23 and the fourth insulating layer 24, diffusion of metal from the first electrode 11 toward the conductor 50 was not confirmed. This is thought to be because there is no potential difference or the potential difference is small between the first electrode 11 and the conductor 50 when a signal is transmitted. Therefore, from the viewpoint of suppressing metal diffusion, it is not necessarily necessary to add carbon to the third insulating layer 23 and the fourth insulating layer 24. In order to suppress peeling or damage of the fourth insulating layer 24, it is preferable that the fourth insulating layer 24 contains silicon, carbon, and nitrogen.

[0047] In the isolator 130 shown in FIG. 8, the fourth insulating layer 24 is separated from the third insulating layer 23. The fourth insulating layer 24 contains silicon, carbon, and nitrogen. The third insulating layer 23 is formed without adding carbon and contains silicon and nitrogen. The third insulating layer 23 is substantially free of carbon. The carbon concentration in the third insulating layer 23 is lower than the carbon concentration in the fourth insulating layer 24.

[0048] The third insulating layer 23 and the fourth insulating layer 24 may be separated from each other or may be in contact with each other along the XY plane. A part of one of the third insulating layer 23 and the fourth insulating layer 24 may be provided on a part of the other. When the third insulating layer 23 contains silicon, carbon, and nitrogen, the leakage current between the first electrode 11 and the second electrode 12 may increase. When the third insulating layer 23 does not substantially contain carbon, the leakage current between the first electrode 11 and the second electrode 12 can be reduced compared to when the third insulating layer 23 contains carbon.

[0049] 9, the first electrode 11 and the second electrode 12 are not spirally shaped but are flat. For example, the first electrode 11 and the second electrode 12 are provided such that the upper surface of the first electrode 11 and the lower surface of the second electrode 12 are parallel to each other.

[0050] The isolator 140 transmits signals using changes in an electric field instead of changes in a magnetic field. Specifically, when the second circuit 2 applies a voltage to the second electrode 12, an electric field is generated between the first electrode 11 and the second electrode 12. Charges corresponding to the electric field strength are accumulated in the first electrode 11. The first circuit 1 detects the flow of charges at this time and generates a signal based on the detection result. As a result, a signal is transmitted between the first electrode 11 and the second electrode 12 with the current being blocked.

[0051] The structure of the isolator 140 can be the same as that of the isolator 100, except for the structures related to the first electrode 11 and the second electrode 12. Like the isolator 100, the isolator 140 can improve reliability.

[0052] The modifications described above can be combined as appropriate. For example, the third insulating layer 23 and the fourth insulating layer 24 in the isolator 120 or 130 may be applied to the isolator 110 or 140.

[0053] Second embodiment FIG. 10 is a plan view illustrating an isolator according to the second embodiment. FIG. 11 is a schematic diagram illustrating a cross-sectional structure of an isolator according to the second embodiment. 10, in the isolator 200 according to the second embodiment, one end of the first electrode 11 is electrically connected to the conductor 50 via a wiring 61. The other end of the first electrode 11 is electrically connected to the first circuit 1 via a wiring 60.

[0054] 11, the first circuit 1 is provided in a substrate 5. The second circuit 2 is provided in a substrate 6 separate from the substrate 5. The pad 62 is electrically connected to a pad 68 provided on the substrate 6 via a wiring 63. The pad 64 is electrically connected to a pad 69 provided on the substrate 6 via a wiring 65. The second circuit 2 is electrically connected to the pads 68 and 69.

[0055] In the isolator 200, the structures according to the embodiments already described can be applied to the structure above the substrate 5. This can improve the reliability of the isolator 200.

[0056] FIG. 12 is a plan view illustrating an isolator according to a first modified example of the second embodiment. Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 12. Fig. 14 is a cross-sectional view taken along line XIV-XIV in Fig. 12. FIG. 15 is a schematic diagram illustrating a cross-sectional structure of an isolator according to a first modified example of the second embodiment. As shown in FIG. 12, an isolator 210 according to a first modification includes a first structure 10-1 and a second structure 10-2.

[0057] 12, 13, and 15, the first structure 10-1 includes an electrode 11-1, an electrode 12-1, insulating layers 21a to 26a, insulating portions 30a, 31a, 33a, 35a, 37a, and 39a, a conductor 50a, a pad 62a, a pad 64a, and a pad 66a. The structures of these components are similar to the structures of the first electrode 11, the second electrode 12, the first insulating layer 21 to the fourth insulating layer 24, the insulating layers 25 and 26, the insulating portion 30, the first insulating portion 31, the insulating portions 33, 35, 37, and 39, the conductor 50, the pad 62, the pad 64, and the pad 66, respectively, shown in FIG.

[0058] 12, 14, and 15, the second structure 10-2 includes an electrode 11-2, an electrode 12-2, insulating layers 21b to 26b, insulating portions 30b, 31b, 33b, 35b, 37b, and 39b, a conductor 50b, a pad 62b, a pad 64b, and a pad 66b. The structures of these components are similar to the structures of the first electrode 11, the second electrode 12, the first insulating layer 21 to the fourth insulating layer 24, the insulating layers 25 and 26, the insulating portion 30, the first insulating portion 31, the insulating portions 33, 35, 37, and 39, the conductor 50, the pad 62, the pad 64, and the pad 66, respectively, shown in FIG.

[0059] 12, pad 62a is electrically connected to pad 62b via wiring 63. Pad 64a is electrically connected to pad 64b via wiring 65. Pad 66a is electrically connected to another conductive member via wiring 67a. Pad 66b is electrically connected to another conductive member via wiring 67b.

[0060] As shown in FIG. 15, the first circuit 1 is provided in a substrate 5. The first structure 10-1 is provided on the substrate 5. The second circuit 2 is provided in a substrate 6. The second structure 10-2 is provided on the substrate 6. One end of the electrode 11-1 is electrically connected to the conductor 50a. The other end of the electrode 11-1 is electrically connected to the first circuit 1. One end of the electrode 11-2 is electrically connected to the conductor 50b. The other end of the electrode 11-2 is electrically connected to the second circuit 2.

[0061] In the isolator 210, the structures according to the embodiments already described can be applied to the structure above the substrate 5 and the structure above the substrate 6. This can suppress diffusion of metal from the electrodes 12-1 and 12-2.

[0062] 12 to 15, a pair of electrodes 11-1 and 12-1 are connected in series with a pair of electrodes 11-2 and 12-2. In other words, the first circuit 1 and the second circuit 2 are doubly insulated by the two pairs of electrodes connected in series. The isolator 210 can improve insulation reliability compared to a structure in which insulation is provided by a single pair of electrodes.

[0063] FIG. 16 is a plan view illustrating an isolator according to a second modification of the second embodiment. FIG. 17 is a schematic diagram illustrating a cross-sectional structure of an isolator according to a second modification of the second embodiment. 16 and 17, an isolator 220 according to a second modified example of the second embodiment differs from the isolator 200 in that both ends of the first electrode 11 are electrically connected to the first circuit 1. The conductor 50 is electrically isolated from the first circuit 1 and the first electrode 11. If the conductor 50 is set to a reference potential, the electrical connection relationship between the first circuit 1, the first electrode 11, and the conductor 50 can be appropriately changed. In this case, in order to reduce the potential difference between the first electrode 11 and the conductor 50, it is preferable that the first electrode 11 and the conductor 50 are set to the same potential.

[0064] FIG. 18 is a schematic diagram illustrating an isolator according to a third modified example of the second embodiment. The isolator 230 according to the third modification includes a first structure 10-1, a second structure 10-2, a third structure 10-3, and a fourth structure 10-4. The first structure 10-1 includes an electrode 11-1 and an electrode 12-1. The second structure 10-2 includes an electrode 11-2 and an electrode 12-2. The third structure 10-3 includes an electrode 11-3 and an electrode 12-3. The fourth structure 10-4 includes an electrode 11-4 and an electrode 12-4. Each electrode is a coil. The first circuit 1 includes a differential driver circuit 1a, a capacitance C1, and a capacitance C2. The second circuit 2 includes a differential receiver circuit 2a, a capacitance C3, and a capacitance C4.

[0065] For example, the differential driver circuit 1a, the capacitance C1, the capacitance C2, the electrodes 11-1, 11-2, 12-1, and 12-2 are formed on a first substrate (not shown). One end of the electrode 11-1 is connected to a first constant potential. The other end of the electrode 11-2 is connected to the capacitance C1. One end of the electrode 11-2 is connected to a second constant potential. The other end of the electrode 11-2 is connected to the capacitance C2.

[0066] One output of the differential driver circuit 1a is connected to a capacitance C1. The other output of the differential driver circuit 1a is connected to a capacitance C2. The capacitance C1 is connected between the differential driver circuit 1a and an electrode 11-1. The capacitance C2 is connected between the differential driver circuit 1a and an electrode 11-2.

[0067] Electrodes 11-1 and 12-1 are stacked with an insulating part sandwiched between them. Electrodes 11-2 and 12-2 are stacked with another insulating part sandwiched between them. The winding direction of electrode 12-1 is opposite to that of electrode 12-2. One end of electrode 12-1 is connected to one end of electrode 12-2.

[0068] For example, the differential receiver circuit 2a, the capacitor C3, the capacitor C4, the electrode 11-3, the electrode 11-4, the electrode 12-3, and the electrode 12-4 are formed on a second substrate (not shown). One end of the electrode 11-3 is connected to a third constant potential. The other end of the electrode 11-3 is connected to the capacitor C3. One end of the electrode 11-4 is connected to a fourth constant potential. The other end of the electrode 11-4 is connected to the capacitor C4.

[0069] One input of the differential receiving circuit 2a is connected to a capacitance C3. The other input of the differential receiving circuit 2a is connected to a capacitance C4. Electrodes 11-3 and 12-3 are stacked with an insulating section in between. Electrodes 11-4 and 12-4 are stacked with another insulating section in between. One end of the electrode 12-3 is connected to one end of the electrode 12-4.

[0070] The operation will be described. In the isolator, a modulated signal is transmitted. In FIG. 18, Vin represents the modulated signal. For example, the edge trigger method or the On-Off Keying method is used for modulating the signal. In either method, Vin is a signal obtained by shifting the original signal to a high frequency band.

[0071] The differential driver circuit 1a passes currents in opposite directions to the electrodes 11-1 and 11-2 in response to Vin. The electrodes 11-1 and 11-2 generate magnetic fields (H1) in opposite directions. When the number of turns of the electrode 11-1 is the same as the number of turns of the electrode 11-2, the magnitudes of the generated magnetic fields are equal to each other.

[0072] The induced voltage in electrode 12-1 due to magnetic field H1 is added to the induced voltage in electrode 12-2 due to magnetic field H1. A current i1 flows through electrodes 12-1 and 12-2. The other end of electrode 12-1 is connected to the other end of electrode 12-3 by a bonding wire. The other end of electrode 12-2 is connected to the other end of electrode 12-4 by another bonding wire. The bonding wire contains, for example, gold. The diameter of the bonding wire is, for example, 30 μm.

[0073] The induced voltages added by the electrodes 12-1 and 12-2 are applied to the electrodes 12-3 and 12-4. A current i2 having the same value as the current i1 flows through the electrodes 12-3 and 12-4. The electrodes 12-3 and 12-4 generate magnetic fields (H2) in opposite directions. When the number of turns of the electrode 12-3 is the same as the number of turns of the electrode 12-4, the magnitudes of the generated magnetic fields are equal to each other.

[0074] The direction of the induced voltage generated in electrode 11-3 by magnetic field H2 is opposite to the direction of the induced voltage generated in electrode 11-4 by magnetic field H2. Current i3 flows through electrodes 11-3 and 11-4. The magnitude of the induced voltage generated in electrode 11-3 is the same as that of the induced voltage generated in electrode 11-4. The sum of the induced voltages generated by electrodes 11-3 and 11-4 is applied to differential receiving circuit 2a, and a modulated signal is transmitted.

[0075] Third embodiment FIG. 19 is a perspective view illustrating a package according to the third embodiment. FIG. 20 is a schematic diagram showing a cross-sectional structure of a package according to the third embodiment. The package 300 according to the third embodiment includes metal members 81a to 81f, metal members 82a to 82f, pads 83a to 83f, pads 84a to 84f, a sealing portion 90, and a plurality of isolators 230, as shown in FIG.

[0076] In the illustrated example, the package 300 includes four isolators 230. That is, four sets of the first structure 10-1 to the fourth structure 10-4 shown in FIG.

[0077] The multiple first structures 10-1 and the multiple second structures 10-2 are provided on a portion of the metal member 81a. For example, the multiple first structures 10-1 and the multiple second structures 10-2 are provided on one substrate 5. The substrate 5 is electrically connected to the metal member 81a. The multiple first circuits 1 are provided in the substrate 5. One first circuit 1 is provided corresponding to a pair of one first structure 10-1 and one second structure 10-2.

[0078] The multiple third structures 10-3 and the multiple fourth structures 10-4 are provided on a portion of the metal member 82a. The multiple third structures 10-3 and the multiple fourth structures 10-4 are provided on one substrate 6. The substrate 6 is electrically connected to the metal member 82a. A multiple second circuits 2 are provided in the substrate 6. One second circuit 2 is provided corresponding to a pair of one third structure 10-3 and one fourth structure 10-4.

[0079] The metal member 81a is further electrically connected to a pad 83a. The pad 83a is electrically connected to the conductor 50a of each of the first structures 10-1 and each of the second structures 10-2. The metal member 82a is further electrically connected to a pad 84a. The pad 84a is electrically connected to the conductor 50b of each of the third structures 10-3 and each of the fourth structures 10-4.

[0080] The metal members 81b to 81e are electrically connected to the pads 83b to 83e, respectively. The pads 83b to 83e are electrically connected to the plurality of first circuits 1, respectively. The metal member 81f is electrically connected to the pad 83f. The pad 83f is electrically connected to the plurality of first circuits 1.

[0081] The metal members 82b to 82e are electrically connected to the pads 84b to 84e, respectively. The pads 84b to 84e are electrically connected to the plurality of second circuits 2, respectively. The metal member 82f is electrically connected to the pad 84f. The pad 84f is electrically connected to the plurality of second circuits 2.

[0082] The sealing portion 90 covers a portion of each of the metal members 81a to 81f and 82a to 82f, the pads 83a to 83f, the pads 84a to 84f, and the multiple isolators 230.

[0083] The metal members 81a to 81f have terminals T1a to T1f, respectively. The metal members 82a to 82f have terminals T2a to T2f, respectively. The terminals T1a to T1f and T2a to T2f are not covered by the sealing portion 90 and are exposed to the outside.

[0084] For example, terminals T1a and T2a are connected to a reference potential. Signals to the respective first circuits 1 are input to terminals T1b to T1e. Signals from the respective second circuits 2 are output to terminals T2b to T2e. Terminal T1f is connected to a power supply for driving the multiple first circuits 1. Terminal T2f is connected to a power supply for driving the multiple second circuits 2.

[0085] According to the third embodiment, it is possible to reduce the possibility of dielectric breakdown of the isolator, and improve the reliability of the package 300. Here, an example in which four isolators 230 are provided has been described, but the package 300 may be provided with one or more other isolators.

[0086] Although some embodiments of the present invention have been illustrated above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. In addition, the above-mentioned embodiments can be implemented in combination with each other. [Explanation of symbols]

[0087] 1 first circuit, 2 second circuit, 5 substrate, 11 first electrode, 11a, 11b metal layer, 12 second electrode, 12a, 12b metal layer, 21 first insulating layer, 22 second insulating layer, 21r, 22r insulating layer, 23 third insulating layer, 24 fourth insulating layer, 25, 26 insulating layer, 30 insulating portion, 31 first insulating portion, 33, 35, 37, 39 insulating portion, 50 conductor, 51 first conductive portion, 51a, 51b metal layer, 52 second conductive portion, 52a, 52b metal layer, 53 third conductive portion, 53a, 53b metal layer, 60, 61 wiring, 62 pad, 63 wiring, 64 pad, 65 wiring, 66 pad, 67 Wiring, 100,100r,110~140 Isolator

Claims

1. A first electrode; a second electrode disposed on the first electrode and spaced apart from the first electrode; a first insulating portion provided between the first electrode and the second electrode, the first insulating portion being located around the second electrode along a first surface, a portion of which is perpendicular to a first direction from the first electrode toward the second electrode; an insulating layer made of silicon nitride, the insulating layer being provided around the second electrode along the first surface and positioned on the first insulating portion; a first insulating layer provided on the second electrode, the first insulating layer including silicon, carbon, and nitrogen, and in contact with a top surface of the second electrode; a conductor provided around the first electrode and the second electrode along the first surface; an insulating portion made of silicon oxide, the insulating portion being provided between the second electrode and the conductor and positioned between the insulating layer and the first insulating layer in the first direction; An isolator comprising:

2. The second electrode is a first metal layer comprising copper or aluminum; a second metal layer including tantalum, the second metal layer being provided between the first insulating portion and the first metal layer, between the insulating layer and the first metal layer, and between the insulating portion and the first metal layer; 2. The isolator of claim 1 , comprising:

3. The isolator according to claim 1 , wherein the conductor is electrically connected to the first electrode.

4. 3. The isolator according to claim 1, wherein the electric potential of the conductor is set to be the same as the electric potential of the first electrode.

5. a second insulating layer disposed over the conductor and comprising silicon, carbon, and nitrogen; The isolator according to claim 1 , wherein the second insulating layer is in contact with an upper surface of the conductor.

6. 6. The isolator according to claim 1, further comprising a third insulating layer made of silicon nitride, the third insulating layer being provided between the first electrode and the first insulating portion.

7. a fourth insulating layer comprising silicon, carbon, and nitrogen; The conductor is a first conductive portion provided around the first electrode along the first surface; a second conductive portion provided on a portion of the first conductive portion; a third conductive portion provided on the second conductive portion and provided around the second electrode along the first surface; Including, The isolator according to any one of claims 1 to 6, wherein the fourth insulating layer is provided around a bottom of the second conductive portion and on another part of the first conductive portion and is in contact with the second conductive portion.

8. 8. The isolator according to claim 1, wherein the carbon concentration in the first insulating layer is equal to or greater than 10 mass % and equal to or less than 45 mass %.

9. 9. The isolator according to claim 1, wherein the hydrogen concentration in the first insulating layer is not less than 0.5 mass % and not more than 5 mass %.

10. 10. The isolator according to claim 1, wherein in the first insulating layer, a mass ratio of nitrogen to silicon is not less than 0.2 and not more than 0.8.

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