Method for manufacturing coil devices

Abstract

To provide a coil device that includes a first coil and a second coil which are insulated by polyimide, and suppresses the deformation of polyimide.SOLUTION: A coil device comprises: a substrate 1 having a first main surface and a second main surface opposite to the first main surface; a first insulation film 2 that is provided so as to be contacted to the substrate 1 in a first direction side in the case where a direction directed from the second main surface to the first main surface is a first direction; a first coil part 8 that is provided so as to be contacted to the first direction side to the first insulation film 2, and is a spiral-like conductive film; a second insulation film 4 that is provided so as to cover the first direction side of a first coil part 8 and the first direction side of the first insulation film 2 where the first coil part 8 is not provided; a second coil part 12 that is provided so as to be contacted to the first direction side of a second insulation film 4, and is the spiral-like conductive film; and a first groove 9 that is provided to the second insulation film 4, and includes a width to the first direction on the first direction side of the second insulation film 4 in a region inner from an outer peripheral end of the second coil part 12 in a plan view.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a coil device and a method for manufacturing the same.

Background Art

[0002] An insulated coil device has a primary coil and a secondary coil provided via an insulating member, and is a coil device for transmitting a signal. In such a coil device, for example, polyimide having a film thickness corresponding to a desired breakdown voltage is used as the insulating member. When the polyimide film is cured by heat, it tends to shrink and deform. In order to obtain a region with little deformation where the coil can be arranged on the upper surface of the film, there is a problem that the size of the coil device has to be increased.

[0003] In Japanese Patent Application Laid-Open No. 2008-218121, there is described a signal transmission device having a primary-side electrode (lower electrode) and a secondary-side electrode (upper electrode) provided via a film of an insulating material such as polyimide, and having grooves formed in the film surface of the insulating material around the upper electrode in a plan view.

Prior Art Documents

Patent Documents

[0007] The coil device according to this disclosure comprises a substrate having a first main surface and a second main surface facing the first main surface; a first insulating film provided in contact with the first direction side of the substrate when the direction from the second main surface toward the first main surface is defined as the first direction; a first coil portion provided in contact with the first direction side of the first insulating film and being a spiral-shaped conductive film in a plan view when viewed in the opposite direction to the first direction; a second insulating film provided so as to cover the first direction side of the first coil portion and the first direction side of the first insulating film where the first coil portion is not provided; a second coil portion provided in contact with the first direction side of the second insulating film and being a spiral-shaped conductive film in a plan view; and one or more grooves provided in the second insulating film, in a region inward from the outer peripheral edge of the second coil portion in a plan view, having a width in the first direction on the first direction side surface of the second insulating film.

[0008] A method for manufacturing a coil device according to this disclosure comprises: a first insulating film forming step of forming a first insulating film on a substrate having a first main surface and a second main surface facing the first main surface, with the direction from the second main surface toward the first main surface being defined as the first direction; a first coil portion forming step of forming a first coil portion that contacts the first insulating film on the first direction side after the first insulating film forming step and is a spiral conductive film in a plan view when viewed in the opposite direction to the first direction; and a second insulating film that covers the first coil portion on the first direction side and contacts the first insulating film where the first coil portion is not provided on the first direction side after the first coil portion forming step. The method comprises: a second insulating film forming step for forming the shape of the outer periphery of the second insulating film; a second coil portion forming step for forming a second coil portion that is in contact with the second insulating film on the first direction side and is a spiral-shaped conductive film in plan view, after the second insulating film forming step or after the second coil portion forming step, heating to harden the second insulating film; and a groove forming step for forming one or more grooves on the first direction side surface of the second insulating film by etching in a region inward from the outer periphery end of the second coil portion in plan view, between the second insulating film forming step and the groove forming step. [Effects of the Invention]

[0009] According to this disclosure, by arranging a groove in a region inward from the outer peripheral edge of the second coil portion of the second insulating film in a plan view, stress due to the contraction of the second insulating film is reduced and dispersed, thereby providing the effect of obtaining a semiconductor device in which deformation of the second insulating film is reduced. [Brief explanation of the drawing]

[0010] [Figure 1] This is a plan view of an insulating coil device according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is a cross-sectional view of an insulated coil device. [Figure 3] This is a flowchart showing a part of the manufacturing method for an insulated coil device according to Embodiment 1 of the present invention. [Figure 4]Cross-sectional view of an insulated coil device in the first insulating film forming step of Embodiment 1 of the present invention. [Figure 5] Cross-sectional view of an insulated coil device in the primary coil forming step of Embodiment 1 of the present invention. [Figure 6] Cross-sectional view of an insulated coil device in the second insulating film forming step of Embodiment 1 of the present invention. [Figure 7] Cross-sectional view of an insulated coil device in the second insulating film forming step of Embodiment 1 of the present invention. [Figure 8] Cross-sectional view of an insulated coil device in the groove forming step of Embodiment 1 of the present invention. [Figure 9] Cross-sectional view of an insulated coil device in the groove forming step of Embodiment 1 of the present invention. [Figure 10] Cross-sectional view of an insulated coil device in the groove forming step of Embodiment 1 of the present invention. [Figure 11] Cross-sectional view of an insulated coil device in the groove forming step of Embodiment 1 of the present invention. [Figure 12] Cross-sectional view of an insulated coil device in the groove forming step of Embodiment 1 of the present invention. [Figure 13] Cross-sectional view of an insulated coil device in the secondary coil forming step of Embodiment 1 of the present invention. [Figure 14] Plan view showing an outline of an insulated coil device. [Figure 15] Cross-sectional view showing an outline of an insulated coil device. [Figure 16] Plan view of an insulated coil device of Embodiment 2 of the present invention. [Figure 17] Cross-sectional view of the insulated coil device of FIG. 16. [Figure 18] Plan view of an insulated coil device of Embodiment 3 of the present invention. [Figure 19] Cross-sectional view of the insulated coil device of FIG. 18. [Figure 20] Flow chart showing a part of the manufacturing method of an insulated coil device of Embodiment 3 of the present invention. [Figure 21]Cross-sectional view of an insulated coil device in the primary coil forming step of Embodiment 3 of the present invention. [Figure 22] Cross-sectional view of an insulated coil device in the second insulating film forming step of Embodiment 3 of the present invention. [Figure 23] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 24] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 25] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 26] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 27] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 28] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 29] Cross-sectional view of an insulated coil device in the secondary coil and groove forming step of Embodiment 3 of the present invention. [Figure 30] Planar view of an insulated coil device in Embodiment 4 of the present invention.

[0011] In the present disclosure, the surface of the substrate on which the coil of the coil device is disposed is defined as the first main surface which is the upper surface, and the surface facing the first main surface is defined as the second main surface which is the lower surface. Further, the direction from the second main surface toward the first main surface is defined as the first direction (Z direction). Furthermore, the direction parallel to the first main surface is defined as the second direction (X direction), the direction orthogonal to the X direction and parallel to the first main surface is defined as the third direction (Y direction). Therefore, the X direction, the Y direction, and the Z direction are orthogonal to each other. Also, for each film constituting the coil device, the surface far from the substrate in the Z direction is referred to as the upper surface, and the surface close to the substrate is referred to as the lower surface. Also, the plan view is, for example, the view from the direction opposite to the first direction, that is, from the direction from the first main surface toward the second main surface onto a plane.

[0012] Embodiment 1 Figure 1 is a plan view showing an insulated coil device 101 of Embodiment 1. Figure 2 is a cross-sectional view showing the section A-A of the insulated coil device 101 in Figure 1. As shown in Figure 2, the insulated coil device 101 has a substrate 1. The substrate 1 has a first main surface which is the upper surface and a second main surface which is the lower surface opposite the first main surface. In this disclosure, the direction from the second main surface toward the first main surface is defined as the first direction for explanation purposes. The insulated coil device 101 further includes a first insulating film 2 provided in contact with the substrate 1 on the first direction side, a primary coil 3 which is a conductive film provided in contact with the first insulating film 2 on the first direction side, a second insulating film 4 provided in contact with the second insulating film 2 on the first direction side, covering the first direction side of the primary coil 3 and not having a first coil portion, a groove 9 provided on the first direction side surface of the second insulating film 4 with a width in the first direction, and a secondary coil 5 which is a conductive film provided in contact with the first direction side surface of the second insulating film 4. The insulated coil device 101 is a device that transmits signals by magnetic coupling between the primary coil 3 and the secondary coil 5 arranged via the second insulating film 4.

[0013] The substrate 1 has a rectangular shape with sides parallel to the X and Y directions. The substrate 1 is made of silicon (Si). The substrate 1 may also be made of, for example, silicon carbide (SiC), gallium nitride (GaN), or an insulating substrate made of glass, ceramics, etc.

[0014] The first insulating film 2 is provided in contact with the upper surface of the substrate 1 so as to cover it. The first insulating film 2 is composed of a silicon oxide film (SiO2), which is a semiconductor material. The first insulating film 2 may also be composed of, for example, a silicon nitride film (Si3N4).

[0015] The primary coil 3 is not shown in Figure 1 because it is located beneath the second insulating film 4, i.e., on the opposite side of the first direction. However, as shown in Figure 2, it is provided in contact with the upper surface of the first insulating film 2 and has the same shape as the secondary coil 5 shown in Figure 1 in plan view. That is, the primary coil 3 is a conductive film provided in contact with the upper surface of the first insulating film 2, and is composed of a first coil portion 8 with a circular spiral shape in plan view, a first electrode 6 positioned in the center of the first coil portion 8 in plan view and connected to one end of the first coil portion 8, to which current is input, and a second electrode 7 positioned on the outer circumference of the first coil portion 8 in plan view and connected to the other end of the first coil portion 8, to which current is output. The material of the primary coil 2 is, for example, aluminum or copper, and the width of the conductive film in the first direction is, for example, 0.1 to 10 μm. The conductor width of the first coil portion 8 in plan view is, for example, 1 to 20 μm.

[0016] The second insulating film 4 is an insulating film formed between the primary coil 3 and the secondary coil 5 for voltage resistance maintenance. By adjusting the film thickness, a desired voltage resistance performance corresponding to the high voltage applied between the two coils can be obtained. The second insulating film 4 is provided in contact with the region inside the outer shape of the upper surface of the first insulating film 2, and in a plan view, it has a rectangular shape with sides parallel to the X and Y directions at its outer edges. The second insulating film 4 is made of polyimide, for example, an insulating organic material. A groove 9 having a width in the first direction is formed on the upper surface of the second insulating film 4. This groove 9 will be described later.

[0017] The secondary coil 5 is provided in contact with the upper surface of the second insulating film 4 and has the same configuration as the primary coil 3. That is, as shown in Figure 1, the secondary coil 5 is a conductive film provided in contact with the upper surface of the second insulating film 2, and is composed of a second coil portion 12 with a circular spiral shape in plan view, a third electrode 10 which is located in the center of the second coil portion 12 in plan view and connected to one end of the second coil portion 12 and to which current is input, and a fourth electrode 11 which is located on the outer circumference of the second coil portion 12 in plan view and connected to the other end of the second coil portion 12 and to which current is output. The material of the secondary coil 5 is, for example, aluminum or copper, and the width of the conductive film in the first direction is, for example, 0.1 to 10 μm. The conductor width of the second coil portion 12 in plan view is, for example, 1 to 20 μm. In Embodiment 1, the primary coil 3 and the secondary coil 5 have the same planar shape, but are not limited to this. Any coil may have a different shape, and may also have different materials and widths in the first direction.

[0018] Now, let's describe the groove 9. In Embodiment 1, as shown in Figure 1, the groove 9 is a first groove located inside the outer peripheral edge of the second coil portion 12 in a plan view, and has a groove 9A located in the region between adjacent conductive films on the spiral inner and outer sides of the second coil portion 12, and a second groove 9B located in the region outside the outer peripheral edge of the second coil portion 12, i.e., at the periphery of the second insulating film 4. Both groove 9A and groove 9B are located in positions that do not overlap the second coil portion 12. That is, the second coil portion 12 is configured so that it does not straddle the step between the upper surface of the second insulating film where the groove 9 is not provided and the bottom surface of the groove 9. Furthermore, both groove 9A and groove 9B have a straight portion extending in a direction parallel to the X direction or the Y direction. Here, the outer peripheral end of the second coil portion 12 refers to the second coil portion 12 located closest to the end of the semiconductor device when viewed in a straight line in any direction from the center of the third electrode 10 toward the end of the insulating coil device 101 in a plan view. Inside the outer peripheral end refers to the space between the outer peripheral end and the third electrode 10 on the line connecting the outer peripheral end and the third electrode 10. In Figure 1, there are multiple grooves 9A and grooves 9B, but there may be only one.

[0019] Furthermore, as shown in Figure 2, the groove 9A is positioned between adjacent conductive films of the second coil portion 12 in a cross-sectional view. Also, when d1 is the width of the second insulating film 4 in the first direction, i.e., the dimension in the Z direction from the interface with the first insulating film 2 to the upper surface of the second insulating film 4, and d2 is the width in the Z direction of the groove 9 provided on the upper surface of the second insulating film 4, d2 is formed to be 50% or less of d1. Reducing d2 in this way has the effect of suppressing the decrease in insulation between the first coil portion 8 and the second coil portion 12.

[0020] Next, the manufacturing method of the insulated coil device 101 of Embodiment 1 will be described. Figure 3 is a flowchart showing the manufacturing flow. Figures 4 to 13 are cross-sectional views corresponding to the cross-section of the insulated coil device 101 shown in Figure 2, showing the same cross-section at each manufacturing process.

[0021] First, in step 1, a first insulating film 2 is deposited in contact with the upper surface of the substrate 1. Figure 4 is a cross-sectional view showing the insulated coil device 101 after step 1 has been performed. The first insulating film 2 can be deposited, for example, by vapor deposition using a thermal CVD apparatus.

[0022] Next, in step 2, a primary coil 3 is formed in contact with the upper surface of the first insulating film 2. Figure 5 is a cross-sectional view showing a cross-section of the insulating coil device 101 after step 2 has been performed. For example, to form the primary coil 3, first a film of a conductive material such as aluminum or copper is deposited on the upper surface of the first insulating film 2 using a sputtering apparatus or the like, and then the primary coil 3 is formed using photoengraving process technology. Photoengraving is a process technology in which a photosensitive resist is applied to the upper surface of a film, the resist is exposed using a photomask on which a desired pattern has been formed, and the pattern is formed through resist development, etching, and resist peeling. In photoengraving in step 2, etching is performed using, for example, dry etching or wet etching.

[0023] Next, in step 3, a second insulating film 4 is formed in contact with the upper surface of the first insulating film 2 on which the primary coil 3 is formed. Figures 6 and 7 are cross-sectional views showing the insulated coil device 101 in step 3. In Embodiment 1, the second insulating film 4 is made of polyimide. To form the second insulating film 4, first, polyimide is applied to cover the entire upper surface of the insulated coil device 101 (Figure 6). Then, the outer periphery of the second insulating film 4 is removed using photoengraving process technology to form a rectangular outer shape (Figure 7). This photoengraving process technology is the same as that described in step 2, but in the photoengraving in step 3, for example, dry etching is used.

[0024] Next, in step 4, grooves 9 are formed on the upper surface of the second insulating film 4. The grooves 9 are formed by photoengraving process technology. Figures 8-12 are cross-sectional views showing the insulated coil device 101 in step 4. First, a positive-type photosensitive resist 20 is applied to cover the entire upper surface of the insulated coil device 101 (Figure 8). Next, the resist 20 is exposed to UV light using a photomask 21 on which the groove pattern 9 is formed (Figure 9). Next, the resist 20 is developed. Here, the photosensitive areas of the resist 20 are removed (Figure 10). Next, the second insulating film 4 in the areas where the resist 20 was removed by etching is etched (Figure 11), and then the resist 20 is removed (Figure 12). In the photoengraving of step 4, anisotropic dry etching is used, for example, when etching the polyimide.

[0025] In step 5, the secondary coil 5 is formed in contact with the upper surface of the second insulating film 4. Figure 13 is a cross-sectional view showing the insulated coil device 101 after step 5 has been performed. The secondary coil 5 is first formed by depositing a film of a conductive material such as aluminum or copper onto the upper surface of the second insulating film 4 using, for example, a sputtering apparatus, and then by a photoengraving process using a photomask on which the pattern of the secondary coil 5 has been formed. This photoengraving process technology is the same as that described in step 2.

[0026] In step 6, the second insulating film 4 is baked by heating it at a high temperature to heat-cur it and stabilize the film quality. The cross-section after step 6 is the same as shown in Figure 13.

[0027] In the description of Embodiment 1, the groove 9 was formed in step 4, the secondary coil 5 was formed in step 5, and finally the heat sealing was performed in step 6. However, the order of steps 4 to 6 can be changed as long as the groove is formed before the heat sealing. That is, the groove 9 may be formed after the secondary coil 5 is formed and then the heat sealing may be performed (step 5 → step 4 → step 6), or the heat sealing may be performed after the groove 9 is formed and then the secondary coil 5 is formed (step 4 → step 6 → step 5).

[0028] Next, the operation of the insulated coil device 101 of Embodiment 1 will be explained. First, the insulated coil device in the case where the groove 9 is not arranged will be explained using Figures 14 and 15. Figure 14 is a plan view showing a schematic of the insulated coil device when it is baked at a high temperature during the baking process, and Figure 15 is a cross-sectional view showing the BB cross section of Figure 14. For simplification, the secondary coil 5 is not shown in Figures 14 and 15. In the insulated coil device, hardening shrinkage of the second insulating film 4 occurs when baking is performed at a high temperature in step 6 of the manufacturing process described above. Due to hardening shrinkage, in the XY direction, as shown in Figure 14, a stress F1 is generated in a plan view from the outer edge of the second insulating film 4 toward the center of the second insulating film 4. Also, in the Z direction, as shown in Figure 15, a stress F2 is generated in a cross-sectional view from the upper surface of the second insulating film 4 toward the first insulating film 2. These F1 and F2 are called shrinkage stresses.

[0029] The hardening of the second insulating film 4 progresses from the periphery to the center because the periphery becomes hotter first. When the shrinkage stress becomes large, as shown in Figure 15, the second insulating film 4, which had the shape shown by the dotted line before hardening, may deform, with the periphery rising in a convex shape in the Z direction. As a result, the flat region 22, which is the area on the upper surface of the second insulating film 4 where no deformation has occurred, shrinks towards the center of the second insulating film 4 in a plan view.

[0030] In Embodiment 1, the average thickness of the second insulating film 4 is reduced by providing grooves 9, thereby reducing shrinkage stresses F1 and F2. Furthermore, by arranging grooves 9 not only on the outside of the second coil portion 12 but also in a region inside the outer peripheral edge of the second coil portion 12, the effect of reducing shrinkage stresses F1 and F2 is further increased, and deformation of the second insulating film 4 can be suppressed. At the same time, by forming the grooves 9 with straight sections extending in the X and Y directions, the upper surface of the second insulating film 4 is divided, and the shrinkage stress F1 is dispersed. As a result, the reduction of the flat region 22 due to deformation can be further suppressed.

[0031] Next, the effects of the insulated coil device 101 of Embodiment 1 will be explained. In an insulated coil device, in order to place the secondary coil 5 on the upper surface of the second insulating film 4, the upper surface must be a flat surface without deformation. However, if deformation of the peripheral edge occurs during sintering, there is a problem that the size of the insulated coil device must be increased in advance by the amount by which the flat region 22 is reduced. In the insulated coil device 101 of Embodiment 1, as described above, the deformation of the second insulating film 4 is reduced by placing the groove 9 inside the outer circumference of the second coil portion 12. This makes it possible to suppress the reduction of the flat region 22 on which the secondary coil 5 can be provided, thereby suppressing the increase in the size of the device and enabling miniaturization. Furthermore, by forming the groove 9 with straight sections extending in the X and Y directions, which are parallel to the outer peripheral edges of the rectangular outer shape of the second insulating film 4, the shrinkage stress of the second insulating film 4 is dispersed, further reducing the deformation of the second insulating film 4 and suppressing the reduction of the flat region 22. Furthermore, by positioning the groove 9 in a region inward from the outer circumference of the second coil portion 12, and ensuring that it does not intersect with the second coil portion 12, the thinning of the second coil portion 12 at the stepped portion of the groove 9 can be reduced, thereby suppressing wire breakage or an increase in electrical resistance.

[0032] In Embodiment 1, the second insulating film 4 is a rectangle with sides parallel to the X and Y directions in a plan view, and the first groove 9A, which is located inside the outer peripheral edge of the second coil portion 12, and the second groove 9B, which is located outside the outer peripheral edge of the second coil portion 12, have portions parallel to the X and Y directions. When the coil device is made into a rectangular shape considering the processability of the outer shape and subsequent mounting workability, and the second insulating film 4 is also made into a rectangle to match, manufacturing workability may be good. However, the second insulating film 4 is not limited to a rectangle and can be any shape. Furthermore, when the second insulating film 4 is any shape, including a rectangle, if at least one of the grooves 9A or 9B has a portion that extends in the same direction as the outer peripheral edge of the second insulating film 4 closest to the groove in a plan view, the shrinkage stress from the outer peripheral edge of the second insulating film 4 toward the center is dispersed, and the deformation of the second insulating film 4 is further suppressed.

[0033] Embodiment 2 In Embodiment 1, an insulating coil device 101 was described in which the outer shape of the second insulating film 4 is rectangular, and grooves 9 extending in a direction parallel to the sides of the outer shape of the second insulating film 4 are formed on the upper surface of the second insulating film 4. In Embodiment 2, an insulating coil device 102 will be described in which spiral grooves 13 are formed in the region between adjacent conductive films on the spiral inner and outer sides of the second coil portion.

[0034] Figure 16 shows a plan view of the insulated coil device 102, which is a semiconductor device of Embodiment 2. Figure 17 shows a cross-sectional view of the insulated coil device 102 along cross-section C-C in Figure 16. As shown in Figures 16 and 17, the insulated coil device 102 has, similar to the insulated coil device 101 of Embodiment 1, a first insulating film 2 provided on the upper surface of the substrate 1, a primary coil 3 which is a conductive film formed in a spiral shape in contact with the upper surface of the first insulating film 2, a second insulating film 4 which covers the upper side of the primary coil 3 and is provided in contact with the upper side of the second insulating film 2 where the first coil portion is not provided, and a secondary coil 5 which is a conductive film formed in a spiral shape in contact with the upper surface of the second insulating film 4. Furthermore, similar to Embodiment 1, the insulated coil device 102 has a groove 13, which is a first groove, located on the upper surface of the second insulating film 4 and positioned inward from the outer peripheral edge of the second coil portion 12, between adjacent conductive films of the second coil portion 12 in a cross-sectional view. However, unlike Embodiment 1, the groove 13 is formed in a spiral shape between adjacent conductive films on the spiral inner and outer sides of the second coil portion 12 in a plan view. The groove 13 may be interrupted in the middle as long as it is spiral-shaped. In addition, in the insulated coil device 102, the outer shape of the second insulating film 4 follows the outer edge of the second coil portion 12.

[0035] The manufacturing method for the insulated coil device 102 of Embodiment 2 is the same as the manufacturing method shown in Embodiment 1, and only the following two points need to be changed. The first point is that in the second insulating film formation step of step 3, the outer shape of the second insulating film 4 is made to follow the outer edge of the second coil portion 12 instead of being rectangular. This can be achieved by changing the photomask used in step 3 to a corresponding one. The second point is that in the groove formation step of step 4, spiral grooves 13 are formed instead of grooves 9 parallel to the X or Y direction. This can be achieved by changing the photomask used in step 4 to a corresponding one.

[0036] Next, the operation and effects of the insulated coil device 102 of Embodiment 2 will be explained. In the insulated coil device 102, spiral grooves 13 are formed between adjacent conductive films in a cross-sectional view of the second coil portion 12, thereby further reducing the average thickness of the second insulating film 4 and simultaneously dividing the upper surface of the second insulating film 4 into finer sections according to the number of turns of the second coil portion 12. This further reduces and disperses the shrinkage stress of the second insulating film 4, suppressing deformation. Furthermore, by shaping the outer form of the second insulating film 4 to follow the outer edge of the second coil portion 12, the shrinkage stress generated in the region of the second insulating film 4 outside the outer edge of the second coil portion 12 can be reduced. As a result, the reduction in the flat region where the secondary coil 5 can be provided can be suppressed, thereby suppressing an increase in the size of the device and enabling miniaturization.

[0037] Embodiment 3 The third embodiment, an insulated coil device 103, is described below. Embodiment 3 is a modification of Embodiment 2. Figure 18 shows a plan view of the insulated coil device 103. Figure 19 shows a cross-sectional view of the insulated coil device 103 along cross-section D-D in Figure 18. In the insulated coil device 103, the first groove 14, which is located inside the outer peripheral edge of the second coil portion 12, is formed in a spiral shape in the region between adjacent conductive films on the spiral inner and outer sides of the second coil portion 12 in a plan view, and the outer shape of the second insulating film 4 follows the outer peripheral edge of the second coil portion 12. Embodiment 3 differs from Embodiment 2 in the manufacturing process of the groove 14 and the secondary coil, and accordingly, as shown in Figure 19, the width of the groove 14 in the direction perpendicular to the first direction in a cross-sectional view is the same as the width between adjacent conductive films of the second coil portion 12 in the direction perpendicular to the first direction.

[0038] The manufacturing method for the insulated coil device 103 of Embodiment 3 is described below. Figure 20 shows the manufacturing flow. Figures 21 to 29 correspond to the cross-section of the insulated coil device 103 shown in Figure 19, and are cross-sectional views showing the same location in each manufacturing process.

[0039] In step 1, a first insulating film 2 is deposited on one side of the substrate 1. Next, in step 2, a primary coil 3 is formed on the first insulating film 2. Figure 21 is a cross-sectional view showing the insulated coil device 103 after step 2 has been carried out. The manufacturing process in steps 1 and 2 is the same as in steps 1 and 2 of Embodiment 1, so a detailed explanation is omitted.

[0040] Next, in step 3, a second insulating film 4 is formed on the upper surface of the first insulating film 2 on which the primary coil 3 is formed. Figure 22 is a cross-sectional view showing a cross-section of the insulating coil device 103 after step 3 has been carried out. The manufacturing process in step 3 is the same as in step 3 of embodiment 1, but as in embodiment 2, the outer shape of the second insulating film 4 is not rectangular but follows the outer edge of the second coil portion 12. This can be achieved by changing the photomask used in step 3 to the corresponding one.

[0041] Next, in step 4, a secondary coil 5 and a groove 14 are formed on the upper surface of the first insulating film 2. This step 4 differs from that of Embodiments 1 and 2, and will be explained in detail below with reference to the figures.

[0042] First, a conductive film 23 made of aluminum, copper, or other materials, which will form the components of the secondary coil 5, is deposited over the entire upper surface of the insulating coil device 103 using, for example, a sputtering apparatus (Figure 23).

[0043] Next, a photosensitive resist 24 is applied to the entire upper surface of the conductive film 20 (Figure 24). Then, the resist 24 is exposed using a photomask 25 on which the pattern of the secondary coil 5 is formed (Figure 25). After that, the resist 24 is developed to remove the resist 24 from the areas that were irradiated with light (Figure 26).

[0044] Next, the conductive film 23 in the area where the resist 24 has been removed is removed by the first etching process. As a result, the secondary coil 5 is formed by the conductive film 23 that was not removed. The etching used in this first etching process does not remove the second insulating film 3. Therefore, at this point, the second insulating film 3 is exposed in the area other than the conductive film 23 that has become the secondary coil 5 in a plan view (Figure 27).

[0045] Next, a second etching process is performed to excavate the upper surface of the second insulating film 3 in the area where the resist 24 has been removed, forming a groove 14. Note that the conductive film 23 of the secondary coil 5 is not removed by the etching used in the second etching process. Therefore, in a cross-sectional view, the width of the groove 14 is equal to the distance between adjacent conductive films of the second coil portion 12 (Figure 28). After that, the resist 24 is removed (Figure 29).

[0046] Finally, in step 5, the second insulating film 4 is cured by sintering. The cross-section of the insulating coil device 103 after sintering is the same as that shown in Figure 29. The sintering process in step 5 may be the same as that in step 6 of Embodiment 1.

[0047] In Embodiment 3, similar to Embodiment 2, spiral grooves 14 are formed between adjacent conductive films of the second coil portion 12, further reducing and dispersing the shrinkage stress of the second insulating film 4 and suppressing deformation. Furthermore, by making the outer shape of the second insulating film 4 conform to the outer edge of the second coil portion 12, shrinkage stress from the region of the second insulating film 4 outside the secondary coil 5 can be reduced. As a result, the region where it is impossible to provide the secondary coil 5 can be reduced, enabling miniaturization of the device size. In addition to the above effects, by changing the formation process of the secondary coil 5 and grooves 14, the resist application, exposure, and development processes in the formation of the secondary coil 5 and grooves 14 can be reduced from two to one compared to Embodiments 1 and 2, and the photomask can be reduced from two sets to one set, resulting in a reduction in lead time and manufacturing costs.

[0048] Similar results can be obtained using processes other than those described above. For example, one such method involves simultaneously etching the conductive film 23 and the second insulating film 4 in areas where the resist 24 has not been formed during the first etching. This can be achieved by performing the first etching using a process that can etch both the conductive film 23 and the second insulating film 4. This method eliminates the need for a second etching step. Another method involves first forming the secondary coil 5 in the first etching step, and then removing the resist 24. After that, the secondary coil 5 formed from the conductive film 23 can be used as a substitute for the resist, and the second etching can be performed on the second insulating film 4. This process can also achieve a similar configuration if the second etching is performed using a process that does not remove the conductive film 23. The choice of which process to adopt depends on the type of materials used for the conductive film 23 and the second insulating film, the specifications and capabilities of the manufacturing equipment, and the cost of the process.

[0049] Embodiment 4 The insulated coil device 104, which is a semiconductor device of Embodiment 4, will now be described. Figure 30 shows a plan view of the insulated coil device 104. As shown in Figure 30, the insulated coil device 104 has, similar to Embodiment 1, a substrate 1, a first insulating film 2 provided on one side of the substrate 1, a primary coil 3 formed of a conductive film on the upper surface of the oxide film 2, a second insulating film 4 formed to cover the primary coil 3 and the area on the upper surface of the first insulating film 2 where the primary coil 3 is not provided, and a secondary coil 5 formed of a conductive film on the upper surface of the second insulating film 4. In Embodiment 4, the upper surface of the second insulating film 4 is further provided with a groove 15 that combines both a first groove positioned inside the outer peripheral edge of the second coil portion 12 and a second groove positioned outside the outer peripheral edge of the second coil portion 12. In Figure 30, multiple grooves 15 are provided, but there may be only one. The second coil portion 12 of the secondary coil 5 is provided straddling the step between the upper surface of the second insulating film 4 where the groove 15 is not provided and the bottom surface of the groove 15.

[0050] In Embodiment 4, since the second coil portion 12 is formed across the step of the groove 15, measures may be taken to increase the width of the second coil portion 12 in the first direction or to decrease the width of the groove 15 in the first direction in order to suppress wire breakage at the step or an increase in resistance due to thinning. For example, the width of the second coil portion 12 in the first direction may be the same as or greater than the width of the groove 15 in the first direction.

[0051] In Embodiment 4, similar to Embodiment 1, by arranging the groove 15 in a region inward from the outer peripheral edge of the second coil portion 12, the reduction and dispersion effect of shrinkage stress can be greatly increased, and deformation of the second insulating film 4 can be suppressed. Furthermore, in Embodiment 4, the groove 15 can be arranged regardless of the shape of the secondary coil 5. For example, the shape and width of the groove 15 can be freely changed to one that offers advantages in terms of manufacturing efficiency and cost.

[0052] In Figure 30 of Embodiment 4, the second insulating film 4 was a rectangle with sides parallel to the X and Y directions in a plan view. The groove 15 was provided to extend in the X and Y directions. However, the second insulating film 4 is not limited to a rectangle and can have any shape. Furthermore, when the second insulating film 4 has any shape, including a rectangle, if the groove 15 has a portion that extends in the same direction as the outer edge of the second insulating film 4 closest to the groove 15 in a plan view, it will disperse the contraction stress from the outer edge of the second insulating film 4 toward the center and further suppress the deformation of the second insulating film 4.

[0053] In embodiments 1 to 4 of this disclosure, the first coil section 8 and the second coil section 12 are not limited to being circular as long as they have the function of a coil, and may be spiral-shaped. In addition to spiral shapes, they may also be circular, polygonal, or a combination of circular and polygonal shapes. Furthermore, the shapes of the first coil section 8 and the second coil section 12 may be different. In addition, the first electrode 6 and the third electrode 10 are arranged in the center of the first coil section 8 and the second coil section 12, respectively, and the second electrode 7 and the fourth electrode 11 are arranged in the spiral outer periphery of the first coil section 8 and the second coil section 12, respectively, but the arrangement positions are not limited to these, and it is sufficient that the first electrode 6 and the second electrode 7 and the third electrode 10 and the fourth electrode 11 are electrically connected via the first coil section 8 and the second coil section 12, respectively.

[0054] Furthermore, the grooves provided in each embodiment may be combined in the region inside and outside the outer peripheral edge of the second coil portion 12. That is, it is possible to combine the respective forms of the first groove located inside the outer peripheral edge of the second coil portion 12 and the second groove located outside the outer peripheral edge of the second coil portion 12.

[0055] An example of such a combination of the first groove and the second groove will be described. In Embodiment 1, the second insulating film 4 has a rectangular outer shape, and the second groove, groove 9B, is placed in the region outside the second coil portion 12. In Embodiment 2, the second insulating film 4 is made to follow the outer edge of the second coil portion 12, and the first groove, a spiral-shaped groove 13, is placed inside the outer edge of the second coil portion 12. For example, by combining these, the second insulating film 4 may have a rectangular outer shape with sides in the X and Y directions, and the spiral-shaped first groove, groove 13, may be placed in the region inside the second coil portion 12, while the second groove, groove 9B, which is parallel to the X or Y direction, may be placed in the region outside the second coil portion 12.

[0056] Another example of the combination of the first groove and the second groove will be described. For example, in the embodiments shown in Embodiment 1 and Embodiment 4, the outer shape of the second insulating film 4 may be made to follow the shape of the second coil portion 12. In this case, since the second insulating film 4 does not exist in the region outside the second coil portion 12, the second groove will also not exist, similar to Embodiment 2 and Embodiment 3.

[0057] While several embodiments of this disclosure have been described, these embodiments are presented as examples only. Various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Furthermore, the embodiments can be combined. The scope of the invention is indicated by the claims rather than the foregoing description, and all modifications are intended to be within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0058] 101, 102, 103, 104 Insulated coil device, 1 Substrate, 2 First insulating film, 3 Primary coil, 4 Second insulating film, 5 Secondary coil, 8 First coil section, 9, 13, 14, 15 Grooves, 12 Second coil section, 20, 24 Resist, 23 Conductor film

Claims

1. A first insulating film forming step, in which a first insulating film is formed on a substrate having a first main surface and a second main surface facing the first main surface, with the direction from the second main surface toward the first main surface being defined as the first direction, and the insulating film is in contact with the substrate on the first direction side. After the first insulating film formation step, a first coil portion formation step is performed, in which a first coil portion is formed that is in contact with the first insulating film on the first direction side and is a spiral-shaped conductive film in a plan view when viewed in the opposite direction to the first direction, After the first coil portion forming step, a second insulating film is formed which covers the first coil portion on the first direction side and contacts the first insulating film where the first coil portion is not provided on the first direction side, and then the shape of the outer periphery of the second insulating film is formed. After the second insulating film formation step, a second coil portion formation step is performed to form a second coil portion that is in contact with the second insulating film on the first direction side, is a spiral-shaped conductive film in plan view, and transmits signals with the first coil portion. After the second insulating film formation step, or after the second coil portion formation step, a curing step is performed in which the second insulating film is heated and hardened. A method for manufacturing a coil device, comprising: a groove forming step, between the second insulating film formation step and the scorching step, in a region inward from the outer peripheral edge of the region corresponding to the second coil portion in a plan view, in which one or more first grooves having depth in the first direction are formed on the first direction side surface of the second insulating film by etching.

2. The groove formation step is performed after the second insulating film formation step, The method for manufacturing a coil device according to claim 1, wherein the second coil portion forming step is performed after the groove forming step.

3. The method for manufacturing a coil device according to claim 1 or claim 2, wherein the first groove and the second coil portion are provided in positions that do not overlap in a plan view.

4. The second coil portion forming step is a step of forming a conductive film on the first direction side surface of the second insulating film, forming a resist in the shape of the second coil portion on the upper surface of the conductive film, and removing the conductive film in a region that does not overlap with the resist in the plan view by etching to form the second coil portion. The method for manufacturing a coil device according to claim 1, wherein the groove forming step is performed after the second coil portion forming step, and is a step of forming the first groove in the second insulating film in a region that does not overlap with the resist in the plan view by etching.

5. The second coil portion forming step is a step of forming a conductive film on the first direction side surface of the second insulating film, forming a resist in the shape of the second coil portion on the upper surface of the conductive film, removing the conductive film in a region that does not overlap with the resist in the plan view by etching, and removing the resist to form the second coil portion. The method for manufacturing a coil device according to claim 1, wherein the groove forming step is performed after the second coil portion forming step, and is a step of forming the first groove by etching in the second insulating film in a region that does not overlap with the second coil portion in a plan view.

6. The method for manufacturing a coil device according to any one of claims 1 to 5, wherein in a plan view, the second insulating film has a rectangular outer shape consisting of sides in a second direction parallel to the first main surface and sides in a third direction perpendicular to the second direction, and the first groove has a straight portion extending in a direction parallel to at least one of the second or third directions.

7. The method for manufacturing a coil device according to any one of claims 1 to 6, wherein in a plan view, each of the first grooves has a portion that extends in the same direction as the outer peripheral end of the second insulating film that is closest to the first groove.

8. The method for manufacturing a coil device according to any one of claims 1 to 5, wherein the first groove is spiral-shaped in a plan view.

9. The method for manufacturing a coil device according to claim 8, wherein in a cross-sectional view of the substrate, the width of the first groove in a direction perpendicular to the first direction is the same as the width between adjacent conductive films of the second coil portion in a direction perpendicular to the first direction.

10. The method for manufacturing a coil device according to claim 1, wherein in a plan view, the second coil portion is arranged across the step difference between the surface of the second insulating film on the first direction side in the region where the first groove is not provided and the bottom surface of the first groove.

11. The method for manufacturing a coil device according to claim 10, wherein in a plan view, each of the first grooves has a portion that extends parallel to the outer peripheral end of the second insulating film in the portion closest to the first groove.

12. The method for manufacturing a coil device according to claim 10 or claim 11, wherein the thickness of the second coil portion in the first direction is greater than or equal to the depth of the first groove in the first direction.

13. A method for manufacturing a coil device according to any one of claims 1 to 12, wherein, in a plan view, one or more second grooves are provided on the surface of the second insulating film on the first direction side, having depth in the first direction, in a region outside the outer peripheral edge of the region corresponding to the second coil portion.

14. The method for manufacturing a coil device according to claim 13, wherein in a plan view, the second insulating film has a rectangular outer shape consisting of sides in a second direction parallel to the first main surface and sides in a third direction perpendicular to the second direction, and the second groove has a straight portion extending in a direction parallel to at least one of the second or third directions.

15. The method for manufacturing a coil device according to claim 13 or claim 14, wherein in a plan view, each of the second grooves has a portion that extends parallel to the outer peripheral edge of the second insulating film in the portion closest to the second groove.

16. The method for manufacturing a coil device according to any one of claims 1 to 15, wherein in a plan view, the second insulating film has an outer shape that follows the outer peripheral end of the second coil portion.

17. The method for manufacturing a coil device according to any one of claims 1 to 16, wherein the depth of the first groove in the first direction is 50% or less of the thickness of the second insulating film in the first direction.

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