isolator

Abstract

The isolation device according to an embodiment of the present application includes a first conductor, a second conductor, and first to third insulating films. The first insulating film is provided between the first conductor and the second conductor, and contains silicon, oxygen, and nitrogen. The second insulating film is provided between the first conductor and the first insulating film, and contains silicon and oxygen, and further contains nitrogen having a composition ratio smaller than that of the first insulating film, or does not contain nitrogen. The first insulating film has a first film thickness between the second conductor and the second insulating film in a first direction from the first conductor toward the second conductor, and the second insulating film has a second film thickness in the first direction thinner than the first film thickness. The third insulating film is provided between the first conductor and the second insulating film, has a third film thickness in the first direction thinner than the first film thickness, and has a composition different from those of the first insulating film and the second insulating film.

Description

[0001] Related applications

[0002] This application claims priority to Japanese Patent Application No. 2021-70841 (filed on April 20, 2021), which is the basic application. This application incorporates the entire contents of the basic application by reference to it. Technical Field

[0003] The implementation involves an isolator. Background Technology

[0004] There are isolators that transmit signals between two magnetically coupled coils. In such isolators, for example, a thick insulating film is preferably provided between the two coils to maintain the desired insulation withstand voltage while preventing insulation breakdown between the coils. However, if the insulating film is thickened, its internal stress increases, causing warping in the wafer on which the insulating film is formed. Therefore, this can sometimes pose obstacles to the manufacturing process of the isolator. Summary of the Invention

[0005] One embodiment provides an isolator comprising two conductors and an insulating film disposed between them, which can reduce the stress on the structure.

[0006] The isolator of this embodiment includes a first conductor, a second conductor facing the first conductor, and first to third insulating films. The first insulating film is disposed between the first conductor and the second conductor and contains silicon, oxygen, and nitrogen. The second insulating film is disposed between the first conductor and the first insulating film and contains silicon and oxygen, further containing nitrogen in a smaller proportion than that of the first insulating film, or containing no nitrogen. The first insulating film has a first film thickness between the second conductor and the second insulating film in a first direction from the first conductor toward the second conductor, and the second insulating film has a second film thickness in the first direction that is thinner than the first film thickness. The third insulating film is disposed between the first conductor and the second insulating film, has a third film thickness in the first direction that is thinner than the first film thickness, and has a composition different from that of the first and second insulating films. Attached Figure Description

[0007] Figure 1 This is a schematic cross-sectional view of the isolator used in the implementation of the method.

[0008] Figure 2 This is a schematic top view showing the isolator in the implementation method.

[0009] Figure 3 (a)~ Figure 4 (c) is a schematic cross-sectional view showing the manufacturing process of the isolator according to the first embodiment.

[0010] Figure 5 This is a schematic cross-sectional view of an isolator representing a modified embodiment.

[0011] Figure 6 This is a schematic cross-sectional view of an isolator showing other variations of the implementation. Detailed Implementation

[0012] Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] In this specification and the figures, elements identical to those already described are labeled with the same symbols, and detailed descriptions are appropriately omitted. The figures are schematic or conceptual, and the relationship between the thickness and width of the parts, the ratio of the sizes between the parts, etc., are not necessarily the same as in reality. Even when representing the same parts, the dimensions and ratios between them are sometimes shown differently according to the figures.

[0014] In the following description, an XYZ orthogonal coordinate system is sometimes used to illustrate the arrangement of the constituent elements. The Z-axis direction is defined as the Z direction, and the two directions perpendicular to and orthogonal to the Z direction are defined as the X and Y directions. Furthermore, the Z direction is sometimes referred to as "up," and its opposite direction as "down." These directions indicate the relative positional relationships of the elements; for example, up and down are not limited to the direction of gravity.

[0015] (First Implementation)

[0016] Figure 1 This is a schematic cross-sectional view showing the isolator 100 according to the first embodiment. The embodiment relates, for example, to a device referred to as a digital isolator, a galvanic isolator, or a galvanic insulating element.

[0017] like Figure 1 As shown, the isolator 100 of the first embodiment includes a substrate SS, a first conductor 10, a second conductor 20, a third conductor 30, a connecting wire 40, a first insulating film IF1, a second insulating film IF2, a third insulating film IF3, a fourth insulating film IF4, a fifth insulating film IF5, a sixth insulating film IF6, a seventh insulating film IF7, an eighth insulating film IF8, a first bonding pad BP1, and a second bonding pad BP2.

[0018] The substrate SS is, for example, a silicon substrate. The substrate SS can be conductive or insulating.

[0019] A first conductor 10 and a second conductor 20 are disposed above a substrate SS. The substrate SS, the first conductor 10, and the second conductor 20 are arranged, for example, along the Z direction. The first conductor 10 is disposed facing the second conductor 20. The first conductor 10 is disposed between the substrate SS and the second conductor 20.

[0020] The first conductor 10 and the second conductor 20 are, for example, planar coils. The first conductor 10 and the second conductor 20 are respectively arranged in a spiral shape in a plane parallel to the XY plane. The first conductor 10 and the second conductor 20 face each other in the Z direction and are magnetically coupled to each other.

[0021] The third conductor 30 is disposed, for example, in a plane parallel to the XY plane, outside the first conductor 10 and the second conductor 20. A connecting wire 40 electrically connects the first conductor 10 and the third conductor 30. The third conductor 30 and the connecting wire 40, for example, electrically connect the first conductor 10 to a peripheral circuit or a peripheral potential. Furthermore, the second conductor 20 is connected, for example, to an external circuit or an external potential.

[0022] A first insulating film IF1 is disposed between the first conductor 10 and the second conductor 20. The first insulating film IF1 comprises, for example, silicon (Si), oxygen (O), and nitrogen (N). The first insulating film IF1 is, for example, a silicon oxynitride (SiON) film.

[0023] A second insulating film IF2 is disposed between the first conductor 10 and the first insulating film IF1. The second insulating film IF2, for example, contains silicon (Si) and oxygen (O). The second insulating film IF2 may further contain nitrogen in a smaller proportion than that in the first insulating film IF1, or it may contain no nitrogen. Furthermore, the relative permittivity of the second insulating film IF2 is, for example, smaller than that of the first insulating film IF1.

[0024] The second insulating film IF2 is, for example, a silicon oxide film (SiO2).

[0025] A third insulating film IF3 is disposed between the first conductor 10 and the second insulating film IF2. The third insulating film IF3 has a different composition from the first insulating film IF1 and the second insulating film IF2. For example, the third insulating film IF3 contains silicon (Si) and nitrogen (N). Furthermore, the relative permittivity of the third insulating film IF3 is, for example, greater than the relative permittivity of the first insulating film IF1 and the second insulating film IF2. The third insulating film IF3 is, for example, a silicon nitride film (SiN). Alternatively, the third insulating film IF3 may also be a silicon oxynitride film (SiON), but the nitrogen content in the third insulating film IF3 is greater than that in the first insulating film IF1. In yet another example, the third insulating film IF3 may also be a silicon carbide film (SiC) or a silicon carbon nitride film (SiCN).

[0026] A fourth insulating film IF4 is disposed between the substrate SS and the first conductor 10. The fourth insulating film IF4 electrically insulates the first conductor 10 from the substrate SS. The fourth insulating film IF4 is, for example, a silicon oxide film.

[0027] A fifth insulating film IF5 is disposed between the fourth insulating film IF4 and the third insulating film IF3. The fifth insulating film IF5 is, for example, a silicon oxide film. The first conductor 10 is disposed within the fifth insulating film IF5 and is in contact with the third insulating film IF3. The third insulating film IF3, for example, has an oxygen-free composition to prevent oxidation of the first conductor 10.

[0028] A sixth insulating film IF6 is disposed on the first insulating film IF1. The sixth insulating film IF6 is, for example, a silicon nitride film.

[0029] The second conductor 20 is disposed between the first insulating film IF1 and the sixth insulating film IF6. For example, the second conductor 20 is disposed within the first insulating film IF1 and is in contact with the sixth insulating film IF6. The sixth insulating film IF6, for example, has an oxygen-free composition to prevent the second conductor 20 from oxidizing.

[0030] A seventh insulating film IF7 is disposed on the sixth insulating film IF6. The seventh insulating film IF7 is, for example, a silicon oxide film.

[0031] An eighth insulating film IF8 is disposed on the seventh insulating film IF7. The eighth insulating film IF8 contains, for example, a resin such as polyimide. The eighth insulating film IF8 is disposed on the seventh insulating film IF7 in such a manner that it surrounds the first bonding pad BP1 and the second bonding pad BP2.

[0032] The first bonding pad BP1 is disposed on the seventh insulating film IF7 and is electrically connected to the third conductor 30 via contact holes disposed in the sixth insulating film IF6 and the seventh insulating film IF7. The first bonding pad BP1 may contain, for example, copper (Cu) or aluminum (Al).

[0033] The second bonding pad BP2 is disposed on the seventh insulating film IF7 and electrically connected to the second conductor 20 via contact holes disposed in the sixth insulating film IF6 and the seventh insulating film IF7. The second bonding pad BP2 may contain, for example, gold (Cu) or aluminum (Al).

[0034] like Figure 1 As shown, the first conductor 10 includes, for example, a metal core 13 and a barrier layer 15. The metal core 13 includes, for example, copper (Cu). The barrier layer 15 includes, for example, tantalum (Ta) or tantalum nitride (TaN). The barrier layer 15 is disposed, for example, between the metal core 13 and the fourth insulating film IF4, and between the metal core 13 and the fifth insulating film IF5. The barrier layer 15 prevents the diffusion of metal atoms from the metal core 13 to the fourth insulating film IF4 and the fifth insulating film IF5.

[0035] The second conductor 20 includes, for example, a metal core 23 and a barrier layer 25. The metal core 23 includes, for example, copper (Cu). The barrier layer 25 is disposed, for example, between the metal core 23 and the first insulating film IF1. The barrier layer 25 is disposed, for example, in contact with the first insulating film IF1. The barrier layer 25 includes, for example, tantalum (Ta) or tantalum nitride (TaN). The barrier layer 25 prevents the diffusion of metal atoms from the metal core 23 to the first insulating film IF1.

[0036] The third conductor 30 includes a first portion 30a, a second portion 30b, and a third portion 30c. The first portion 30a, the second portion 30b, and the third portion 30c are arranged along the Z direction. The second portion 30b is disposed between the first portion 30a and the third portion 30c, electrically connecting the first portion 30a and the third portion 30c. The third portion 30c is disposed at the same level as the second conductor 20 in the Z direction.

[0037] The first portion 30a of the third conductor 30 is disposed at the same level as the first conductor 10 in the Z direction. That is, the first portion 30a is disposed within the fifth insulating film IF5. The first portion 30a of the third conductor 30 is formed, for example, simultaneously with the first conductor 10, and includes a metal core 31 and a barrier layer 33. The barrier layer 33 is disposed, for example, between the metal core 31 and the fourth insulating film IF4, and between the metal core 31 and the fifth insulating film IF5. The barrier layer 33 prevents the diffusion of metal atoms from the metal core 31 to the fourth insulating film IF4 and the fifth insulating film IF5.

[0038] The second part 30b of the third conductor 30 extends along the -Z direction (opposite to the Z direction) in the first insulating film IF1, the second insulating film IF2 and the third insulating film IF3, and is connected to the first part 30a.

[0039] The second part 30b includes a metal core 35 and a barrier layer 36. The metal core 35 contains, for example, copper (Cu). The barrier layer 36 contains, for example, tantalum (Ta) or tantalum nitride (TaN). The barrier layer 36 is disposed, for example, between the metal core 35 and the first insulating film IF1, between the metal core 35 and the second insulating film IF2, between the metal core 35 and the third insulating film IF3, and between the metal core 35 and the first part 30a. The barrier layer 36 prevents, for example, the diffusion of metal atoms from the metal core 35 to the first insulating film IF1, the second insulating film IF2, and the third insulating film IF3.

[0040] The third portion 30c of the third conductor 30 is positioned at the same level as the second conductor 20 in the Z direction. That is, the third portion 30c is disposed within the first insulating film IF1 and contacts the sixth insulating film IF6. The third portion 30c is formed, for example, simultaneously with the second conductor 20, and includes a metal core 37 and a barrier layer 38. The barrier layer 38 is disposed, for example, between the metal core 37 and the first insulating film IF1, and between the metal core 37 and the second portion 30b. The barrier layer 38 prevents the diffusion of metal atoms from the metal core 37 to the first insulating film IF1.

[0041] The third part 30c is connected to the second part 30b. In addition, the third part 30c is electrically connected to the first bonding pad BP1.

[0042] Connecting wiring 40 is disposed between the fourth insulating film IF4 and the fifth insulating film IF5. Connecting wiring 40, for example, contains copper (Cu). Connecting wiring 40 is connected to the lower surface of the outermost portion of the first conductor 10 and the lower surface of the first portion 30a of the third conductor 30.

[0043] In the isolator 100 of this embodiment, the second conductor 20 is electrically insulated from the first conductor 10 by a first insulating film IF1, a second insulating film IF2, and a third insulating film IF3. The first insulating film IF1, for example, has a first film thickness T1 in the Z direction between the second conductor 20 and the second insulating film IF2. The second insulating film IF2 has a second film thickness T2 in the Z direction. The third insulating film IF3 has a third film thickness T3 in the Z direction.

[0044] The insulation withstand voltage between the first conductor 10 and the second conductor 20 is determined by the total thickness (T1+T2+T3) of the first insulating film IF1, the second insulating film IF2, and the third insulating film IF3. That is, by increasing the total thickness (T1+T2+T3), the insulation withstand voltage between the first conductor 10 and the second conductor 20 can be improved. The total thickness of the first insulating film IF1, the second insulating film IF2, and the third insulating film IF3 is preferably 5 micrometers (μm) or more. Furthermore, it is more preferably 8 μm or more.

[0045] For example, if a silicon substrate is used as the substrate SS, and silicon oxide films are used for the first insulating film IF1 and the second insulating film IF2, thickening the first insulating film IF1 and the second insulating film IF2, and setting the total thickness (T1+T2+T3) to 5μm or more, then the internal stress of the first insulating film IF1 and the second insulating film IF2 increases, causing warping in the substrate SS. Therefore, during the manufacturing process of the isolator 100, it may sometimes cause obstacles to the automated handling of wafers.

[0046] In the isolator 100, by using, for example, a silicon oxynitride (SiON) film as the first insulating film IF1, the stress in the first insulating film IF1 can be reduced, and wafer warping can be suppressed. That is, instead of a silicon oxide film, by using a silicon oxynitride film with a suitably controlled nitrogen composition ratio, the stress in the first insulating film IF1 can be reduced.

[0047] Furthermore, the first film thickness T1 of the first insulating film IF1 is thicker than the second film thickness T2 of the second insulating film IF2. The first film thickness T1 of the first insulating film IF1 is also thicker than the third film thickness T3 of the third insulating film IF3. That is, by increasing the first film thickness T1 of the first insulating film IF1, wafer warping can be suppressed, while the desired insulation withstand voltage is obtained between the first conductor 10 and the second conductor 20.

[0048] Figure 2 This is a schematic top view showing the isolator 100 according to the first embodiment. Figure 2 In the diagram, the upper surface of the isolator 100 is shown, excluding the sixth insulating film IF6, the seventh insulating film IF7, and the eighth insulating film IF8. It should be noted that... Figure 1 It is along Figure 2 A cross-sectional view of line A1-A2 in the diagram.

[0049] like Figure 2 As shown, the isolator 100 further includes a first circuit 50, a second circuit 60, a connection wiring 70, and a third bonding pad BP3. The first circuit 50 is electrically connected to the first conductor 10. The second circuit 60 is electrically connected to the second conductor 20.

[0050] One of the first circuit 50 and the second circuit 60 is used, for example, as a transmitting circuit. The other of the first circuit 50 and the second circuit 60 is used, for example, as a receiving circuit. Hereinafter, the first circuit 50 will be described as a transmitting circuit and the second circuit 60 as a receiving circuit.

[0051] The first circuit 50 is electrically connected to one end of the first conductor 10 (planar coil). The first circuit 50 is electrically connected to the first conductor 10 located below the second conductor 20 via connecting wire 70. The other end of the first conductor 10 is electrically connected to the third conductor 30 via connecting wire 40 (see reference). Figure 1 ).

[0052] The second circuit 60 is electrically connected to one end of the second conductor 20 (planar coil) via the first metal lead WR1 and the second bonding pad BP2. Furthermore, the second circuit 60 is electrically connected to the second conductor 20 via the second metal lead WR2 and the third bonding pad BP3.

[0053] The third bonding pad BP3 is, for example, disposed on the seventh insulating film IF7, located at the other end of the second conductor 20. The third bonding pad BP3 and the second bonding pad BP2 (see reference) Figure 1 Similarly, it is electrically connected to the other end of the second conductor 20 via contact holes (not shown) provided in the sixth insulating film IF6 and the seventh insulating film IF7.

[0054] like Figure 2 As shown, a first bonding pad BP1 is disposed on a third conductor 30. The third conductor 30 is electrically connected to an external circuit (not shown) or a reference potential, for example, via a metal lead (not shown) bonded to the first bonding pad BP1. Alternatively, a first portion 30a of the third conductor 30 may be connected to a first reference potential, for example, without via a metal lead on the first bonding pad BP1. The first reference potential is, for example, a first ground potential.

[0055] The first circuit 50 may also be disposed on the substrate SS and electrically connected to the first conductor 10. The first circuit 50 may include, for example, a plurality of transistors (not shown) disposed between the substrate SS and the fourth insulating film IF4, and wiring (not shown) disposed in the fourth insulating film IF4.

[0056] The first circuit 50, for example, sends a signal (current) suitable for transmission via magnetic coupling between the first conductor 10 and the second conductor 20 to the first conductor 10. That is, an induced electromotive force corresponding to a change in the magnetic field of the first conductor 10 is generated in the second conductor 20, and current flows between the second conductor 20 and the second circuit 60. The second circuit 60 detects the current flowing in the second conductor 20 and generates a signal corresponding to the detection result. Thus, a signal can be transmitted between the first conductor 10 and the second conductor 20.

[0057] The second circuit 60 is disposed on another substrate (not shown) and is disposed in a manner having a second ground potential that is different from that of the first circuit 50 disposed on the substrate SS.

[0058] The isolator 100 may also include one of the first circuit 50 or the second circuit 60, or be provided independently of either. For example, it may also be configured according to... Figure 2 The first circuit 50, the second circuit 60, the first conductor 10 and the second conductor 20 shown are respectively disposed on different substrates, and are configured to transmit and receive signals between the first circuit 50 and the second circuit 60 via the first conductor 10 and the second conductor 20 which are electrically insulated and magnetically coupled to each other.

[0059] In addition, isolator 100 can function individually, but multiple isolators 100 can also be connected in series to function as a double-insulated isolator.

[0060] The third conductor 30 is arranged along the XY plane in a manner that surrounds the first conductor 10 and the second conductor 20. The first part 30a of the third conductor 30 (refer to...) Figure 1 The third conductor 30 is arranged along a plane parallel to the XY plane in a manner that surrounds the first conductor 10. The third portion 30c of the third conductor 30 surrounds the second conductor 20 along the XY plane.

[0061] The second portion 30b of the third conductor 30 is disposed on the first portion 30a. Multiple second portions 30b are disposed and arranged along the first portion 30a. The second portions 30b extend along the Z direction. The lower end of the second portion 30b is connected to the first portion 30a, and the upper end of the second portion 30b is connected to the third portion 30c (see reference). Figure 1 ).

[0062] Next, refer to Figure 3 (a)~ Figure 4 (c) A method for manufacturing the isolator 100 according to the first embodiment will be described. Figure 3 (a)~ Figure 4 (c) is a cross-sectional view showing a part of the manufacturing process of isolator 100. Figure 3 (a)~ Figure 4 (c) is along Figure 2 The schematic diagram corresponding to the cross section of line A1-A2 in the diagram.

[0063] like Figure 3 As shown in (a), a third insulating film IF3, a second insulating film IF2, and a first insulating film IF1 are sequentially formed on the fifth insulating film IF5. A first portion 30a of the third conductor 30 is formed in the fifth insulating film IF5. Furthermore, in a portion not shown, a first conductor 10 is formed in the fifth insulating film IF5.

[0064] The first insulating film IF1, the second insulating film IF2, and the third insulating film IF3 are formed, for example, using plasma-enhanced chemical vapor deposition (CVD). The first insulating film IF1 is, for example, a silicon oxynitride film. The second insulating film IF2 is, for example, a silicon oxide film. The third insulating film IF3 is, for example, a silicon nitride film.

[0065] like Figure 3 As shown in (b), an etching mask 41 is formed on the first insulating film IF1. The etching mask 41 has an opening 41f located above the first portion 30a of the third conductor 30. The etching mask 41 is, for example, a photoresist.

[0066] like Figure 3As shown in (c), the first insulating film IF1 is selectively removed using an etching mask 41 to form the contact hole CH. The first insulating film IF1 is removed, for example, using RIE (Reactive Ion Etching). The first insulating film IF1 is etched, for example, under conditions where the etching rate of the silicon oxynitride film is at least several times that of the silicon oxide film. Thus, the etching time can be controlled such that etching stops at the moment when the bottom surface of the contact hole CH reaches the second insulating film IF2.

[0067] like Figure 4 As shown in (a), the remainder of the second insulating film IF2 is removed, exposing the third insulating film IF3 on the bottom surface of the contact hole CH. The second insulating film IF2 is selectively removed, for example, by using the RIE of the etching mask 41. The second insulating film IF2 is etched, for example, under conditions where the etching rate of the silicon oxide film exceeds 10 times the etching rate of the silicon nitride film.

[0068] like Figure 4 As shown in (b), the third insulating film IF3 is selectively removed, exposing the first portion 30a of the third conductor 30 to the bottom surface of the contact hole CH. The third insulating film IF3 is selectively removed, for example, by using the RIE of the etching mask 41.

[0069] like Figure 4 As shown in (c), after removing the etch mask 41, a second portion 30b of the third conductor 30 is formed inside the contact hole CH. The second portion 30b is formed in a manner that is electrically connected to the first portion 30a. The second portion 30b is formed, for example, by forming tantalum nitride (TaN) covering the inner surface of the contact hole CH using reactive sputtering, and then filling the interior of the contact hole CH using Cu plating.

[0070] In the aforementioned manufacturing process, for example, if the second insulating film IF2 is not formed and the first insulating film IF1 is formed directly on the third insulating film IF3, it becomes difficult to stop the etching of the first insulating film IF1 at the moment the third insulating film IF3 is exposed. That is, since both the first insulating film IF1 and the third insulating film IF3 contain nitrogen (N), it becomes difficult to set etching conditions with a high selectivity between the etching of the first insulating film IF1 and the third insulating film IF3. Therefore, the first insulating film IF1 and the third insulating film IF3 are etched continuously, and the etching stops at the moment the first portion 30a of the third conductor 30 is exposed.

[0071] In this etching process, the etching time is controlled such that etching stops when the first portion 30a of the third conductor 30 is exposed to the bottom surface of the contact hole CH across the entire surface of the wafer. Therefore, due to the uneven etching within the wafer surface, a portion of the first portion 30a is exposed to the etching atmosphere of the first insulating film IF1 and the third insulating film IF3 for an extended period. As a result, while the first portion 30a is etched, residue containing components of the first portion 30a remains, for example, within the chamber of the etching apparatus.

[0072] The first portion 30a of the third conductor 30 contains, for example, copper (Cu). Therefore, etching residues containing Cu sometimes remain in the chamber, causing adverse conditions such as etching gas deactivation. To avoid this, chamber cleaning is performed frequently to remove the etching residues, reducing manufacturing efficiency.

[0073] In contrast, during the manufacturing process of isolator 100, the etching of the first insulating film IF1 is stopped at the moment the second insulating film IF2 is exposed. Afterward, selective etching of the remaining portion of the second insulating film IF2 and the third insulating film IF3 becomes possible. This shortens the time the first portion 30a of the third conductor 30 is exposed to the etching atmosphere. Consequently, the generation of etching residue containing components of the first portion 30a is suppressed, extending the chamber cleaning interval.

[0074] For example, shortening the etching time of the third insulating film IF3 can shorten the time the first portion 30a of the third conductor 30 is exposed to the etching atmosphere. That is, the third film thickness T3 of the third insulating film IF3 is preferably thinner than the second film thickness T2 of the second insulating film IF2. Considering the difference in their respective etching rates, the ratio of the second film thickness T2 to the third film thickness T3 (T2 / T3) is preferably at least 5 times. Furthermore, the ratio of the first film thickness T1 to the second film thickness T2 is set proportionally to the difference in etching rates. The film thickness ratio (T1 / T2) is preferably about 2 times.

[0075] Figure 5 This is a schematic cross-sectional view of the isolator 110, illustrating a modified example of the implementation method. (See attached image.) Figure 5 As shown, isolator 110 further comprises a ninth insulating film IF9 and a tenth insulating film IF10.

[0076] A ninth insulating film IF9 is disposed between the first insulating film IF1 and the sixth insulating film IF6. The ninth insulating film IF9 is, for example, a silicon nitride film. The ninth insulating film IF9 has a thickness T1 greater than that of the first insulating film IF1 (see reference). Figure 1 ) thin film thickness in the Z direction.

[0077] A tenth insulating film IF10 is disposed between the ninth insulating film IF9 and the sixth insulating film IF6. The tenth insulating film IF10 has a thickness in the Z direction that is thinner than the first film thickness T1 of the first insulating film IF1. Furthermore, the tenth insulating film IF10 contains a material with a greater selectivity for etching compared to the material of the ninth insulating film IF9. The tenth insulating film IF10 is, for example, a silicon oxide film.

[0078] In this example, the second conductor 20 is disposed in the ninth insulating film IF9 and the tenth insulating film IF10. The second conductor 20 is disposed, for example, inside a groove extending from the upper surface of the tenth insulating film IF10 to the depth of the first insulating film IF1.

[0079] The ninth insulating film IF9 is used, for example, as an etch stop film for the tenth insulating film IF10 during the formation of the second conductor 20. That is, a groove is formed extending from the upper surface of the tenth insulating film IF10 to the depth of the ninth insulating film IF9, and then the ninth insulating film IF9 is etched. The thickness of the ninth insulating film IF9 in the Z direction is thinner than the thickness of the tenth insulating film IF10 in the Z direction. This makes it easier to control the position of the lower end of the second conductor 20.

[0080] The lower end of the second conductor 20 is, for example, located at a level lower than the boundary between the first insulating film IF1 and the ninth insulating film IF9. In other words, the distance between the lower ends of the first conductor 10 and the second conductor 20 is shorter than the distance between the first conductor 10 and the ninth insulating film IF9. As a result, the stress on the insulating film between the first conductor 10 and the second conductor 20 can be alleviated.

[0081] The third portion 30c of the third conductor 30 is formed in the same manner as the second conductor 20. That is, the third portion 30c is disposed within the ninth insulating film IF9 and the tenth insulating film IF10. The lower end of the third portion 30c is located at a level lower than the boundary between the first insulating film IF1 and the ninth insulating film IF9.

[0082] Figure 6 This is a schematic cross-sectional view of the isolator 200, illustrating other variations of the embodiment. The first conductor 10 and the second conductor 20 of the isolator 200 are respectively arranged in a flat plate shape and positioned facing each other. The second conductor 20 is electrically insulated from the first conductor 10 by a first insulating film IF1, a second insulating film IF2, and a third insulating film IF3.

[0083] When viewed along the Z-direction, the first conductor 10 and the second conductor 20 may also have circular, elliptical, or polygonal shapes. The first conductor 10 and the second conductor 20 are arranged, for example, such that the upper surface of the first conductor 10 and the lower surface of the second conductor 20 become parallel.

[0084] The isolator 200 uses changes in the electric field to transmit signals instead of changes in the magnetic field. For example, if the potential of the first conductor 10 (input side) is changed through the first circuit 50, the amount of charge induced in the second conductor 20 (output side) changes. As a result, charge flows between the second conductor 20 and the second circuit 60. The second circuit 60 detects the voltage caused by this change in charge and generates a signal based on the detection result. Thus, a signal can be transmitted between the first conductor 10 and the second conductor 20.

[0085] In this example, the first insulating film IF1 also contains silicon (Si), oxygen (O), and nitrogen (N), which can reduce its stress and suppress wafer warpage. Furthermore, as the second insulating film IF2, by using an insulating film that does not contain nitrogen (N) or an insulating film with a nitrogen composition ratio smaller than that of the first insulating film IF1, etching residues can be suppressed during the manufacturing process of the isolator 200, thereby improving manufacturing efficiency.

[0086] The above embodiments of the present invention have been illustrated, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are also included in the scope of the invention as described in the claims and its equivalents. Furthermore, the above-described embodiments can be combined with each other.

Claims

1. An isolator comprising: First conductor; The second conductor faces the first conductor; A first insulating film, disposed between the first conductor and the second conductor, comprises silicon, oxygen, and nitrogen; A second insulating film is disposed between the first conductor and the first insulating film, comprising silicon and oxygen, further comprising nitrogen in a smaller proportion than that of the nitrogen in the first insulating film, or containing no nitrogen, wherein the first insulating film has a first film thickness in a first direction from the first conductor toward the second conductor, and the second insulating film is disposed such that it has a second film thickness in the first direction that is thinner than that of the first film thickness; A third insulating film is disposed between the first conductor and the second insulating film, having a third film thickness in the first direction that is thinner than the first film thickness, and having a composition different from that of the first insulating film and the second insulating film. A sixth insulating film covers the second conductor, which is disposed between the first insulating film and the sixth insulating film; A first intermediate insulating film is disposed between the first insulating film and the sixth insulating film, and comprises a material different from the first insulating film; as well as The second intermediate insulating film is disposed between the first intermediate insulating film and the sixth insulating film, and comprises a material different from that of the first intermediate insulating film; The second conductor is disposed within the first and second intermediate insulating films. The distance between the first conductor and the second conductor is shorter than the distance between the first conductor and the first intermediate insulating film. The lower end of the second conductor is located at a level lower than the boundary between the first insulating film and the first intermediate insulating film.

2. The isolator according to claim 1, wherein, The second insulating film has a smaller relative permittivity than the first insulating film.

3. The isolator according to claim 1, wherein, The first insulating film comprises silicon oxynitride, and the second insulating film comprises silicon oxide.

4. The isolator according to claim 1, wherein, The third insulating film contains silicon and nitrogen. When the third insulating film is oxygen-free or contains oxygen, the nitrogen composition ratio in the third insulating film is greater than the nitrogen composition ratio in the first insulating film.

5. The isolator according to claim 1, wherein, The third insulating film contains silicon and oxygen and nitrogen. The nitrogen composition ratio in the third insulating film is greater than that in the first insulating film.

6. The isolator according to claim 1, wherein, The third insulating film contains silicon nitride.

7. The isolator according to claim 1, wherein, The third insulating film has a relative permittivity that is greater than that of the first insulating film and the second insulating film.

8. The isolator according to claim 1, further comprising: a substrate arranged parallel to the first conductor and the second conductor in the first direction; and A fourth insulating film is disposed between the substrate and the first conductor. The first conductor is disposed between the substrate and the second conductor.

9. The isolator according to claim 8, wherein, The fourth insulating film contains silicon oxide.

10. The isolator according to claim 8, further comprising a fifth insulating film disposed between the third insulating film and the fourth insulating film, wherein the first conductor is disposed in the fifth insulating film.

11. The isolator according to claim 10, wherein, The fifth insulating film contains silicon oxide.

12. The isolator according to claim 10, further comprising: The wiring is disposed at the boundary between the fourth insulating film and the fifth insulating film and is electrically connected to the first conductor; A third conductor, disposed within the first insulating film, the second insulating film, the third insulating film, and the fifth insulating film, extends along the first direction at a position spaced apart from the first conductor and the second conductor, and is connected to the wiring; and The first bonding pad is electrically connected to the third conductor.

13. The isolator according to any one of claims 1 to 12, wherein, The second conductor is disposed in the first insulating film.

14. The isolator according to claim 1, wherein, The sixth insulating film comprises silicon nitride. The first intermediate insulating film contains silicon nitride. The second intermediate insulating film contains silicon oxide.

15. The isolator according to claim 1, further comprising: A seventh insulating film, which covers the sixth insulating film, has a different composition from the sixth insulating film; and The second bonding pad is disposed on the seventh insulating film and is electrically connected to the second conductor via contact holes disposed in the sixth and seventh insulating films.

16. The isolator according to claim 15, wherein, The seventh insulating film contains silicon oxide.

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