JP7664800B2 - Isolation Devices - Google Patents

Description

An embodiment of the present invention relates to an insulating device.

Isolation devices transmit signals by using changes in magnetic or electric fields while blocking current. There is a demand for improving the life span of these isolation devices.

International Publication No. 2014/112179

The problem that this invention aims to solve is to provide an insulating device that can improve its lifespan.

The insulating device according to the embodiment includes an insulating film, a first coil provided inside the insulating film, and a second coil provided inside the insulating film and positioned above the first coil. A gap is formed in the insulating film outside the second coil when viewed from a first direction from the first coil toward the second coil.

FIG. 1 is a plan view illustrating an insulating device according to a first embodiment. 2 is a cross-sectional view of the insulating device in FIG. 1 as viewed from the direction of arrows AA. FIG. 11 is an explanatory diagram showing an example of forming a gap in an insulating layer. 3 is an explanatory diagram showing an example of a distance between the gap and a second coil in FIG. 2 and a stress state around the gap. FIG. FIG. 3 is a cross-sectional view similar to FIG. 2 illustrating an insulating device according to a second embodiment. FIG. 4 is a cross-sectional view similar to FIG. 2 , illustrating an insulating device according to a third embodiment.

Hereinafter, an embodiment 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.

FIG. 1 is a plan view illustrating an insulating device according to a first embodiment.
FIG. 2 is a cross-sectional view of the insulating device in FIG. 1 as viewed from the direction of arrows AA.

The isolation device 100 is, for example, called a digital isolator, a galvanic isolator, or a galvanic isolation element. As shown in FIG. 1 and FIG. 2, the isolation device 100 includes a first circuit 1, a second circuit 2, a substrate 5, a first coil 11, a second coil 12, an insulating film 20, and a conductor 50. The insulating film 20 is provided on the substrate 5. The first coil 11 is provided inside the insulating film 20. The second coil 12 is provided inside the insulating film 20 and is located above the first coil 11. The conductor 50 is provided inside the insulating film 20, surrounding the first and second coils 11 and 12.

The insulating film 20 has a first insulating part 21 in which the first coil 11 is provided, a second insulating part 22 in which the second coil 12 is provided, and an insulating layer 23 located between the first insulating part 21 and the second insulating part 22. The insulating film 20 also has a third insulating part 24 located between the first insulating part 21 and the insulating layer 23, a fourth insulating part 25 located between the insulating layer 23 and the second insulating part 22, and fifth to seventh insulating parts 26 to 28 located on the second insulating part 22. As shown in FIG. 2, the insulating film 20 is laminated in the Z direction in the order of the first insulating part 21, the third insulating part 24, the insulating layer 23, the fourth insulating part 25, the second insulating part 22, the fifth insulating part 26, the sixth insulating part 27, and the seventh insulating part 28 from the bottom. Note that the fifth to seventh insulating parts 26 to 28 are omitted in FIG. 1.

In the explanation of the embodiment, an XYZ Cartesian coordinate system is used. The direction from the first coil 11 to the second coil 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 explanation, the direction from the first coil 11 to the second coil 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 coil 11 and the second coil 12 and are unrelated to the direction of gravity.

As shown in FIG. 2, the first insulating portion 21 is provided on the substrate 5. The first coil 11 is provided inside the first insulating portion 21. The third insulating portion 24 is provided on the first insulating portion 21. The third insulating portion 24 is provided between the first coil 11 and the insulating layer 23. The third insulating portion 24 is in contact with the first coil 11.

The insulating layer 23 is provided on the first coil 11 and the first insulating part 21 via the third insulating part 24. The insulating layer 23 has multiple layers stacked along the first direction. In this example, the insulating layer 23 has a first layer 23a and a second layer 23b located on the first layer 23a. In the first direction, the second layer 23b has a greater thickness than the first layer. The insulating layer 23 may be one layer or three or more layers. The second coil 12 is provided on the insulating layer 23 (second layer 23b). That is, the insulating layer 23 is located between the first coil 11 and the second coil 12.

The fourth insulating portion 25 is provided on the insulating layer 23. The fourth insulating portion 25 is provided between the insulating layer 23 and the second insulating portion 22 in the Z direction (first direction). The fourth insulating portion 25 is located around the second coil 12 along the XY plane. "Around the second coil 12" means a region including the outside and inside of the second coil 12. That is, at least a part of the second coil 12 is provided inside the fourth insulating portion 25. "Outside the second coil 12" means a region radially outward from the outermost conductor of the wound second coil 12. In contrast, "inside the second coil 12" means a region radially inward from the outer edge of the outermost conductor of the wound second coil 12, and means a region where the wound conductor is arranged. The fourth insulating portion 25 is in contact with the second coil 12. The dielectric constant of the material used for the fourth insulating part 25 is higher than the dielectric constant of the material used for the insulating layer 23.

The second insulating part 22 is provided on the fourth insulating part 25. The second insulating part 22 is provided around the second coil 12 along an XY plane perpendicular to the Z direction. In other words, the second coil 12 is provided inside the second insulating part 22. The second coil 12 penetrates the fourth insulating part 25 and the second insulating part 22 in the Z direction.

In the example shown in Figures 1 and 2, the first coil 11 and the second coil 12 are formed in a circular spiral shape along the XY plane. Note that the first coil 11 and the second coil 12 are not limited to a circular spiral shape, and may be formed in, for example, a rectangular spiral shape. The first coil 11 and the second coil 12 face each other in the Z direction. At least a portion of the second coil 12 is aligned with at least a portion of the first coil 11 in the Z direction.

The fifth insulating portion 26 is provided on the second insulating portion 22 and the second coil 12. The fifth insulating portion 26 is in contact with, for example, the second coil 12. The sixth insulating portion 27 is provided on the fifth insulating portion 26. The seventh insulating portion 28 is provided on the sixth insulating portion 27. The sixth insulating portion 27 and the seventh insulating portion 28 are provided with a pad 62 connected to the second electrode 12 and a pad 66 connected to a conductor 50 described below. The pad 62 is connected to the second circuit 2 via a wiring 63. The pad 66 is connected to a conductive member (not shown) via a wiring 67.

The conductor 50 is arranged around the first coil 11 and the second coil 12 along the XY plane. The conductor 50 is connected to the first coil 11, for example. 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 located within the first insulating portion 21 and arranged around the first coil 11. When viewed from above, the first conductive portion 51 has a shape of, for example, a ring. The first conductive portion 51 is connected to the first coil 11, for example.

The second conductive portion 52 is provided on a part of the first conductive portion 51. The shape of each second conductive portion 52 is a column with the axial direction in the Z direction, for example a rectangular column. A plurality of second conductive portions 52 are provided along the first conductive portion 51. That is, the plurality of second conductive portions 52 are provided intermittently and spaced apart from each other along the annular first conductive portion 51. The second conductive portions 52 are located within the third insulating portion 24 and the insulating layer 23 and extend in the vertical direction (first direction).

The third conductive portion 53 is provided on the plurality of second conductive portions 52. The third conductive portion 53 is located within the fourth insulating portion 25 and the second insulating portion 22 and is located around the second coil 12. When viewed from above, the third conductive portion 53 has a circular ring shape, for example, the same as the first conductive portion 51. A fifth insulating portion 26 is provided on the third conductive portion 53.

In the example shown in FIG. 1, one end of the first coil 11 (one end of the coil) is electrically connected to the first circuit 1 via a wiring 60. The other end of the first coil 11 (the other end of the coil) is electrically connected to the first circuit 1 via a wiring 61.

One end of the second coil 12 (one end of the coil) is electrically connected to the second circuit 2 via a pad 62 and a wiring 63. The other end of the second coil 12 (the other end of the coil) is electrically connected to the second circuit 2 via a pad 64 and a wiring 65. For example, the pad 62 is provided on one end of the second coil 12. The pad 64 is provided on the other end of the second coil 12. 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 coil 12 in the Z direction. The pads 62 and 64 may be formed integrally with the second coil 12.

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. The conductor 50 is connected to the reference potential, and the conductor 50 can be prevented from becoming a floating potential. This can prevent leakage of the magnetic field generated from the first coil 11 and the second coil 12, and can also prevent an external magnetic field from reaching the first coil 11 and the second coil 12.

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 from electromagnetic waves directed toward the first circuit 1 from outside the substrate 5 and the conductor 50. As a result, the operation of the first circuit 1 can be made more stable.

Either the first circuit 1 or the second circuit 2 is used as a transmitting circuit. The other of the first circuit 1 and the second circuit 2 is used as a receiving/transmitting circuit. Here, we will explain the case where the first circuit 1 is a transmitting/receiving circuit and the second circuit 2 is a receiving/transmitting circuit.

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

Next, an example of the material of each component of the insulating device 100 will be described.
The first coil 11, the second coil 12, and the conductor 50 each include, for example, a metal. The first coil 11, the second coil 12, and the conductor 50 each include, for example, at least one metal selected from the group consisting of copper and aluminum. In order to suppress heat generation in the first coil 11 and the second coil 12 when transmitting a signal, it is preferable that the electrical resistance of these coils is low. From the viewpoint of reducing electrical resistance, it is preferable that the first coil 11 and the second coil 12 each include copper.

The first insulating portion 21, the insulating layer 23, the second insulating portion 22, and the sixth insulating portion 27 contain silicon and oxygen. For example, the first insulating portion 21, the insulating layer 23, the second insulating portion 22, and the sixth insulating portion 27 contain silicon oxide. The first insulating portion 21, the insulating layer 23, the second insulating portion 22, and the sixth insulating portion 27 may further contain nitrogen. For example, the nitrogen concentration of the second layer 23b of the insulating layer 23 is higher than the nitrogen concentration of the first layer 23a.

The seventh insulating section 28 contains an insulating resin such as polyimide or polyamide. The third insulating section 24 and the fifth insulating section 26 contain silicon and nitrogen. The third insulating section 24 and the fifth insulating section 26 contain, for example, silicon nitride. The substrate 5 contains silicon and an impurity. The impurity is at least one selected from the group consisting of boron, phosphorus, arsenic, and antimony.

The fourth insulating portion 25 includes at least one selected from the group consisting of a first material including silicon and nitrogen, a second material including aluminum and oxygen, a third material including tantalum and oxygen, a fourth material including hafnium and oxygen, a fifth material including zirconium and oxygen, a sixth material including strontium, titanium, and oxygen, a seventh material including bismuth, iron, and oxygen, and an eighth material including barium, titanium, and oxygen. For example, the fourth insulating portion 25 includes silicon nitride. The dielectric constant of the fourth insulating portion 25 is higher than the dielectric constant of the insulating layer 23 and higher than the dielectric constant of the second insulating portion 22.

For example, the fourth insulating section 25 contains silicon and nitrogen, and the insulating layer 23 and the second insulating section 22 contain silicon, oxygen, and nitrogen. In this case, the nitrogen concentration in the fourth insulating section 25 is higher than the nitrogen concentration in the insulating layer 23 and higher than the nitrogen concentration in the second insulating section 22.

Next, we will explain the void 70 formed inside the insulating film 20.

1, a gap 70 is formed in the insulating film 20 outside the second coil 12 when viewed from the first direction from the first coil 11 toward the second coil 12. In other words, the gap 70 is located inside the insulating film 20 and is formed along the outer periphery of the second coil 12 in a plan view. "Outside the second coil 12" refers to the area radially outward from the outermost conductor of the wound second coil 12. In contrast, "inside the second coil 12" refers to the area radially inward from the outer edge of the outermost conductor of the wound second coil 12, and refers to the area where the wound conductor is arranged.

The void 70 is an air layer. The void 70 reduces the residual stress in the insulating film 20 that occurs when the insulating device 100 is manufactured. As a result, the void 70 improves the life of the insulating device 100. The size, length, and shape of the void 70 are set by experiments and simulations, taking into account the effect of reducing residual stress, the rigidity of the insulating device 100, and the like. The reduction in stress in the insulating film 20 by the void 70 will be explained later.

2, the void 70 is formed in the insulating layer 23. In this example, the void 70 extends downward from the upper end 23b1 of the insulating layer 23. The lower end of the void 70 is located at the lower end of the insulating layer 23. That is, the void 70 extends across multiple layers, including the second layer 23b and the first layer 23a. In this case, the void 70 is formed so that the first coil 11 and the second coil 12 are not connected to each other. For example, the upper end of the void 70 does not contact the second coil 12, and the lower end does not contact the first coil 11. Also, if the upper end of the void 70 contacts the second coil 12, the lower end does not contact the first coil 11. Or, if the lower end of the void 70 contacts the first coil 11, the upper end does not contact the second coil 12. In other words, an insulating portion is provided at least either between the gap 70 and the first coil 11 or between the gap 70 and the second coil 12. This makes it possible to stably maintain the insulating state between the first coil 11 and the second coil 12.

As shown in FIG. 1, the void 70 surrounds the second coil 12 when viewed from the first direction. That is, the void 70 extends in a circular shape along the outermost conductor of the second coil 12. This makes it possible to effectively reduce residual stress in the insulating film 20 outside the first coil 11 and the second coil 12.

The gap 70 is provided between the second coil 12 and the conductor 50. Specifically, the gap 70 is provided closer to the second coil 12. In other words, the gap 70 is provided closer to the second coil 12 than the midpoint between the second coil 12 and the conductor 50 (the dashed dotted line B-B in FIG. 2). This makes it possible to effectively reduce the stress remaining in the area outside the second coil 12.

Next, a method for forming the voids 70 in the insulating film 20 will be described.
3A and 3B are explanatory diagrams showing an example of a method for forming a void in an insulating layer. Fig. 3A shows a state in which an insulating layer 23 has been formed. Fig. 3B shows a case in which a void 70 is formed in the insulating layer 23. Fig. 3C shows a case in which a fourth insulating portion 25 has been formed on the insulating layer 23 and the void 70.

First, as shown in FIG. 3(a), the first insulating portion 21 is formed on the substrate 5 by chemical vapor deposition (CVD). Then, a recess in which the first coil 11 and the first conductive portion 51 are embedded is formed by reactive ion etching (RIE). The first coil 11 and the first conductive portion 51 are embedded in the recess, and then the third insulating portion 24 and the insulating layer 23 are formed on the first insulating portion 21 and the first coil 11 by CVD.

3(b), when forming the void 70, a resist 110 is formed on the insulating layer 23, and an opening is formed in the area where the void 70 is to be formed. In this state, the void 70 extending in the vertical direction can be formed in the insulating layer 23 by RIE using the resist 110 as a mask. After that, the resist 110 is removed. Then, as shown in FIG. 3(c), a fourth insulating section 25 is formed on the insulating layer 23 and the void 70 by CVD. At this time, the forming conditions of the fourth insulating section 25 are controlled so that the fourth insulating section 25 does not fill the void 70. The fifth to seventh insulating sections 26 to 28, the second coil 12, and the second and third conductive sections 52 and 53 are also formed by CVD and RIE in the same manner. In this way, the insulating device 100 is manufactured.

In the insulating device 100 manufactured in this manner, residual stress occurs inside the insulating film 20 during manufacturing. For example, if this residual stress is applied to a portion of the second coil 12 where the electric field is strong, the life of the insulating device 100 may be shortened. The portion of the second coil 12 where the electric field is strong is, for example, near the conductor located at the outermost part of the second coil 12. Therefore, a gap 70 is formed inside the insulating film 20 to reduce this residual stress.

Figure 4 is an explanatory diagram showing an example of the distance between the gap and the second coil in Figure 2 and the stress state around the gap. The dotted characteristic line 81 in Figure 4 shows the stress state when the gap 70 is not formed. On the other hand, the solid characteristic line 82 in Figure 4 shows the stress state when the gap 70 is formed. Here, an example is shown in which the insulating layer 23 is silicon oxide containing nitrogen, and the nitrogen concentration of the second layer 23b is higher than the nitrogen concentration of the first layer 23a.

As shown by the characteristic line 81, if the void 70 is not formed, a large residual stress (tensile stress) occurs in the second layer 23b of the insulating layer 23. Therefore, the insulating layer 23 is formed with a void 70 extending in the vertical direction at a position within a horizontal distance D from the second coil 12. The distance D is, for example, 4 μm. The void 70 also extends downward from the upper end 23b1 of the insulating layer 23. The void 70 allows the insulating layer 23 to deform due to the residual stress. This makes it possible to reduce the residual stress (tensile stress) of the second layer 23b as shown by the characteristic line 82. As a result, the residual stress can be reduced in the upper part of the insulating layer 23 where the electric field is concentrated, and the life of the insulating device 100 is improved.

FIG. 5 is a cross-sectional view similar to FIG. 2, illustrating an insulating device according to a second embodiment.
In the above-described first embodiment, an example has been described in which the gap 70 is formed outside the second coil 12. However, the embodiment of the present invention is not limited to this, and for example, as in a second embodiment shown in Fig. 5, another gap 72 different from the gap 70 may be formed in the insulating layer 23 between the first coil 11 and the second coil 12. This makes it possible to reduce residual stress around the other gap 72.

6A and 6B are cross-sectional views similar to those of FIG. 2, illustrating an insulating device according to a third embodiment. Fig. 6A illustrates a case where the void is formed only in the topmost insulating layer. Fig. 6B illustrates a case where the void extends above the insulating layer.
In the above-described first embodiment, the case where the void 70 is formed across a plurality of layers of the insulating layer 23 has been described as an example. However, the embodiment of the present invention is not limited to this, and the length dimension of the void in the first direction can be set arbitrarily, for example, as in the third embodiment shown in FIG. 6. As shown in FIG. 6(a), the void 74 may be formed only in the topmost layer (second layer 23b) of the insulating layer 23. Also, as shown in FIG. 6(b), the void 76 may have its upper end extended to the third insulating portion 24 or the second insulating portion 22, or its lower end extended halfway through the first layer 23a.

In the above-described first embodiment, the gap 70 is described as surrounding the second coil 12 when viewed from the first direction. However, the embodiment of the present invention is not limited to this. For example, the gap may be formed by dividing the gap in the circumferential direction on the outside of the second coil 12. Also, the gap may be formed only in a part of the outside of the second coil 12.

The above-described embodiment makes it possible to realize an insulating device that can improve its lifespan.

The embodiment may include the following features.
(Configuration 1)
An insulating film;
A first coil provided inside the insulating film;
a second coil provided inside the insulating film and positioned above the first coil;
Equipped with
An insulating device, in which a gap is formed in the insulating film on the outside of the second coil when viewed in a first direction from the first coil toward the second coil.
(Configuration 2)
the insulating film has an insulating layer located between a first insulating portion having the first coil provided therein and a second insulating portion having the second coil provided therein;
2. The insulating device of claim 1, wherein the void is formed in the insulating layer.
(Configuration 3)
3. The insulating device of claim 2, wherein the void extends downward from an upper end of the insulating layer.
(Configuration 4)
the insulating layer has a plurality of layers stacked along the first direction,
4. The insulating device of claim 2 or 3, wherein the gap extends through the layers.
(Configuration 5)
the insulating layer has a plurality of layers stacked along the first direction,
4. The insulating device according to claim 2 or 3, wherein the void is formed only in the topmost layer of the insulating layer.
(Configuration 6)
An insulating device described in any one of configurations 1 to 5, wherein the gap surrounds the second coil when viewed from the first direction.
(Configuration 7)
An insulating device according to any one of configurations 1 to 6, wherein another gap is formed in the insulating layer in a portion between the first coil and the second coil.
(Configuration 8)
An insulating device according to any one of configurations 1 to 7, wherein the gap is formed within 4 μm of the second coil.
(Configuration 9)
An insulating device described in any one of configurations 1 to 8, wherein the gap is formed so that the first coil and the second coil are not in communication with each other.
(Configuration 10)
An insulating device according to any one of configurations 1 to 9, wherein the first coil and the second coil are formed in a circular spiral shape.
(Configuration 11)
a conductor provided inside the insulating film and connected to the first coil,
An insulating device described in any one of configurations 1 to 10, wherein the gap is provided between the second coil and the conductor.

Although several 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 variations are included within the scope and gist of the invention, as well as within the scope of the invention and its equivalents described in the claims. Furthermore, the above-mentioned embodiments can be implemented in combination with each other.

REFERENCE SIGNS LIST 1 First circuit 2 Second circuit 5 Substrate 11 First coil 12 Second coil 20 Insulating film 21 First insulating portion 22 Second insulating portion 23 Insulating layer 23a First layer 23b Second layer 23b1 Upper end 24 Third insulating portion 25 Fourth insulating portion 26 Fifth insulating portion 27 Sixth insulating portion 28 Seventh insulating portion 50 Conductor 51 First conductive portion 52 Second conductive portion 53 Third conductive portion 60, 61, 63, 65, 67 Wiring 62, 64, 66 Pad 70, 74, 76 Void 72 Other voids 81, 82 Characteristic line 100 Insulating device 110 Resist

Claims (9)

An insulating film;
A first coil provided inside the insulating film;
a second coil provided inside the insulating film and positioned above the first coil;
Equipped with
a gap is formed in the insulating film on an outer side of the second coil when viewed in a first direction from the first coil toward the second coil ,
the insulating film has an insulating layer located between a first insulating portion having the first coil provided therein and a second insulating portion having the second coil provided therein;
the void is formed in the insulating layer,
the insulating layer has a plurality of layers stacked along the first direction,
The air gap extends through the layers . The isolation device of claim 1 , wherein the void extends downward from an upper end of the insulating layer. the insulating layer has a plurality of layers stacked along the first direction,
3. The insulating device according to claim 1 , wherein the void is formed only in the uppermost layer of the insulating layers. The insulating device according to claim 1 , wherein the gap surrounds the second coil when viewed from the first direction. 5. The insulating device according to claim 1, wherein another gap is formed in a portion of the insulating layer between the first coil and the second coil. The insulating device according to claim 1 , wherein the gap is formed at a position within 4 μm from the second coil. The insulating device according to claim 1 , wherein the gap is formed so that the first coil and the second coil do not communicate with each other. The insulating device according to claim 1 , wherein the first coil and the second coil are formed in a circular spiral shape. a conductor provided inside the insulating film and connected to the first coil,
The insulating device according to claim 1 , wherein the gap is provided between the second coil and the conductor.

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