This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-194811, filed on Nov. 30, 2021, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a MEMS sensor and a MEMS sensor manufacturing method.
In the related art, there is known an acceleration sensor including a comb-like fixed electrode and a comb-like movable electrode formed of a part of a device substrate. An insulating film is embedded in a base end of each tooth of the fixed electrode and the movable electrode.
The insulating film forms an isolator that electrically insulates each tooth of the fixed electrode and the movable electrode. The isolator performs a function of electrically insulating portions located on both sides of the isolator, and also performs a function of mechanically connecting the portions. In other words, the isolator may also be called an isolation joint.
The isolator is configured by forming a trench recessed in the device substrate in a thickness direction thereof and extending in a direction that traverses the electrode in a plan view, and forming an insulating layer on an inner wall surface of the trench. The insulating layer is circumferentially continuous along an inner peripheral wall surface of the trench in the plan view. At a central portion in a width direction of the isolator, insulating layers face each other in the width direction, and a seam extending along the trench is formed. The isolator may be broken along the seam.
Some embodiments of the present disclosure provide a MEMS sensor and a MEMS sensor manufacturing method capable of suppressing breakage of an isolator along a seam.
According to an embodiment of the present disclosure, there is provided a MEMS sensor, which includes: a conductive device-side substrate including a cavity in a thickness direction of the conductive device-side substrate; a MEMS electrode arranged in the cavity; a support extending in a first direction toward the MEMS electrode from a peripheral wall of the cavity and connected to the MEMS electrode to support the MEMS electrode; and an isolator configured to traverse the support in a second direction intersecting the first direction in a plan view to isolate the support into a first support on the side of the MEMS electrode and a second support on the side of the device-side substrate such that the first support and the second support are electrically insulated from each other in the first direction, wherein the isolator includes: a trench recessed in the thickness direction with respect to the device-side substrate; insulating layers formed on inner wall surfaces of the trench; and joining layers formed on the insulating layers and including portions facing each other in the first direction and at least partially joined to each other in the first direction.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that the following description is merely an example, and does not limit the present disclosure, its applications, or its uses. Moreover, the drawings are schematic, and ratios of respective dimensions are different from actual ratios.
The device-side substrate assembly 2 includes a device-side substrate 10 formed in a rectangular shape in a plan view. In the following description, for the sake of convenience, when seen in a plan view, a longitudinal direction of the device-side substrate 10 is referred to as an X direction, a lateral direction of the device-side substrate 10 is referred to as a Y direction, and a thickness direction of the device-side substrate 10 is referred to as a Z direction. In other words, the Y direction is orthogonal to the X direction in a plan view, and the Z direction is orthogonal to both the X direction and the Y direction. In
The lid-side substrate assembly 3 includes a lid-side substrate 90 which is smaller than the device-side substrate 10 in the X direction.
The device-side substrate 10 is constituted by a conductive silicon substrate. As shown in
As shown in
The first peripheral wall 12 of the cavity 11 is formed with a first support 15 extending in the −X direction and connected to the sensor 5 to support the sensor 5 from the +X-direction side. The second peripheral wall 13 of the cavity 11 is formed with a second support 16 extending in the +X direction and connected to the sensor 5 to support the sensor 5 from the −X-direction side. Each of the first support 15 and the second support 16 is formed in a pair in the Y direction by a part of the device-side substrate 10.
As shown in
The movable electrode 20 includes a spring mechanism 21 formed by a part of the device-side substrate 10 at the +X-direction end. The movable electrode 20 may be displaced in the X direction, the Y direction, and the Z direction via the spring mechanism 21. The spring mechanism 21 is branched into two ends on the +X-direction side, each of which is connected to a pair of first supports 15.
The fixed electrode 30 includes a first fixed electrode 31 positioned on a +Y-direction half portion and a second fixed electrode 32 positioned on a −Y-direction half portion. Each of the first fixed electrode 31 and the second fixed electrode 32 is connected to a pair of second supports 16. An oxide film 18 is formed on a +Z-direction surface of each of the pair of second supports 16. The oxide film 18 allows the first fixed electrode 31 and the second fixed electrode 32 to bend in the Z direction, which improves detectability of changes in capacitance in the Z direction by the sensor 5.
In the sensor 5, when the movable electrode 20 is displaced due to acceleration, the change in capacitance between the movable electrode 20 and the fixed electrode 30 corresponding to the displacement of the movable electrode 20 is taken out as an electric signal from a pad 40, which will be described later.
An isolator 50 is formed in each of the pair of first supports 15 to isolate the first support 15 into a first portion on the side of the MEMS electrode and a second portion on the side of the device-side substrate 10 to electrically insulate the first portion and the second portion in the X direction. The isolator 50 extends in the X direction to traverse the first support 15 in a plan view. As shown in
The isolator 50 includes a trench 51 recessed in the Z direction with respect to the device-side substrate 10, trench insulating layers 52 continuously formed on inner wall surfaces of the trench 51 in a circumferential direction thereof, and trench joining layers 53 continuously formed on the trench insulating layers 52 in the circumferential direction. At least portions of the trench joining layers 53 facing each other in the X direction are joined to each other. The trench insulating layers 52 are formed of silicon oxide films. The trench joining layers 53 are formed of polysilicon. The trench joining layers 53 are joined to each other at least on the side of the first main surface 10a of the device-side substrate 10 in the trenches 51.
As shown in
A main insulating layer 17 is formed on the first main surface 10a of the device-side substrate 10 in a region excluding the movable electrode 20 and the fixed electrode 30. The main insulating layer 17 is, for example, a silicon oxide film. A plurality of pads 40 are formed on the main insulating layer 17 outside the accommodation space Z. The pad 40 is an electrode pad having conductivity. The pad 40 is formed of AlSi in the present embodiment. The pad 40 is electrically connected to the sensor 5 via a conductive path 60.
The pad 40 includes a first pad 41 positioned at the +X-direction end, a second pad portion 42 positioned on the +Y-direction side at the −X-direction end, and a third pad 43 positioned on the −Y-direction side at the −X-direction end. The first pad 41, the second pad 42, and the third pad 43 are electrically connected to the movable electrode 20, the first fixed electrode 31, and the second fixed electrode 32, respectively, via the conductive path 60.
The conductive path 60 connecting the first pad 41 and the movable electrode 20 will be described below as an example. The conductive path 60 includes a MEMS electrode wiring 61 connected to the sensor 5, a pad wiring 62 connected to the pad 40, and an inner conductive path 70 connecting the MEMS electrode wiring 61 and the pad wiring 62.
As shown in
The pad wiring 62 is formed on the main insulating layer 17 outside the accommodation space Z. The pad wiring 62 extends in the X direction and includes a pad wiring first end 62a connected to the first pad 41 and a pad wiring second end 62b positioned on the side of the sensor 5.
The inner conductive path 70 includes a trench 71 extending in the X direction from the inside to the outside of the accommodation space Z and recessed in the −Z direction with respect to the first main surface 10a of the device-side substrate 10, trench insulating layers 72 formed on the inner wall surfaces of the trench 71, and trench conductive layers 73 formed on the trench insulating layers 72. The inner conductive path 70 includes an inner conductive path first end 70a positioned inside the accommodation space Z and an inner conductive path second end 70b positioned outside the accommodation space Z. The inner conductive path first end 70a faces the MEMS electrode wiring second end 61b in the Z direction in a plan view. The inner conductive path second end 70b faces the pad wiring second end 62b in the Z direction in a plan view.
The trench insulating layers 72 are silicon oxide films. The trench conductive layers 73 are formed of conductive polysilicon. The inner conductive path 70 is formed to be flush with the first main surface 10a of the device-side substrate 10 in the Z direction.
A first contact hole 17a penetrating in the Z direction at a position facing the MEMS electrode wiring first end 61a, a second contact hole 17b penetrating in the Z direction at a position between the MEMS electrode wiring second end 61b and the inner conductive path first end 70a, and a third contact hole 17c penetrating in the Z direction at a position between the pad wiring second end 62b and the inner conductive path second end 70b are formed in the main insulating layer 17.
A first contact 81 is embedded in the first contact hole 17a . A second contact 82 is embedded in the second contact hole 17b . A third contact 83 is embedded in the third contact hole 17c. The first to third contacts 81 to 83 are conductive members. The first to third contacts 81 to 83 are formed of AlSi in the present embodiment.
Therefore, the MEMS electrode wiring 61 is connected to the sensor 5 via the first contact 81 and connected to the inner conductive path 70 via the second contact 82. The pad wiring 62 is connected to the inner conductive path 70 via the third contact 83. Accordingly, the conductive path 60 includes the MEMS electrode wiring 61 on the main insulating layer 17 inside the accommodation space Z, the inner conductive path 70 extending from the inside to the outside of the housing space Z and positioned inside the device-side substrate 10 in the thickness direction thereof, that is, embedded in the device-side substrate 10, and the pad wiring 62 on the main insulating layer 17 outside the accommodation space Z.
As shown in
As described above, the device-side substrate assembly 2 includes at least the device-side substrate 10, the sensor 5, the pad 40, the isolator 50, and the conductive path 60.
As shown in
The lid-side substrate 90 includes a recess 92 formed inside the peripheral bank 91. The recess 92 is formed by selectively digging, in the +Z direction, a portion facing the device-side substrate 10 in the Z direction. A position and a shape of the recess 92 are not limited to those shown in
A bonding pad 93 is formed on a top surface of the peripheral bank 91 facing the −Z direction. The bonding pad 93 is formed over the entire circumference of the peripheral bank 91.
A bonding material 94 that bonds the device-side substrate assembly 2 and the lid-side substrate assembly 3 is formed in a rectangular annular shape along the peripheral bank 91. The bonding material 94 is, for example, glass frit containing conductive particles. The bonding material 94 is bonded to the bonding layer 19 for the device-side substrate assembly 2 and bonded to the bonding pad 93 for the lid-side substrate assembly 3. The device-side substrate assembly 2 and the lid-side substrate assembly 3 are joined by the bonding material 94, and the accommodation space Z in which the sensor 5 is accommodated is formed between the device-side substrate assembly 2 and the lid-side substrate assembly 3.
Next, a method of manufacturing the MEMS sensor 1 will be described. First, a method of manufacturing the device-side substrate assembly 2 will be described with reference to
The first semiconductor wafer 101 has a first main surface 101a and a second main surface 101b corresponding to the first main surface 10a and the second main surface 10b of the device-side substrate 10, respectively. Hereinafter, in the first main surface 101a of the first semiconductor wafer 101, a region corresponding to the bonding material 94 is referred to as a seal region Es, a region surrounded by the seal region Es is referred to as a device region Ed, and a region outside the seal region Es is referred to as a pad region Ep.
First, the entire first main surface 101a of the first semiconductor wafer 101 is thermally oxidized. Thus, a first thermal oxide film 102 is formed on the first main surface 101a of the first semiconductor wafer 101. The first thermal oxide film 102 is then patterned and etched to form openings in the regions where the trench 51 of the isolator 50 and the trench 71 of the inner conductive path 70 are to be formed. Then, the first semiconductor wafer 101 is dug down by anisotropic etching using the first thermal oxide film 102 as a hard mask to form the trenches 51 and 71. That is, the trench 51 of the isolator 50 and the trench 71 of the inner conductive path 70 are formed at the same time.
Next, as shown in
Next, as shown in
Now, the polysilicon 104 deposited on the trench thermal oxide film 103 in the trenches 51 and 71 will be described with reference to
Specifically, the trench thermal oxide film 103 integrally includes a trench first thermal oxide film 103a formed on a first sidewall 55a on the +X-direction side of the trench 51, a trench second thermal oxide film 103b formed on a second sidewall 55b on the −X-direction side of the trench 51, a trench third thermal oxide film 103c formed on a third sidewall 55c on the +Y-direction side of the trench 51, a trench fourth thermal oxide film 103d formed on a fourth sidewall 55d on the −Y-direction side of the trench 51, and a trench fifth thermal oxide film 103e formed on a bottom wall 55e on the −Z-direction side of the trench 51. The trench first thermal oxide film 103a and the trench second thermal oxide film 103b are spaced apart from each other in the X direction, and the trench third thermal oxide film 103c and the trench fourth thermal oxide film 103d are spaced apart from each other in the Y direction.
The polysilicon 104 integrally includes a first polysilicon 104a deposited on the trench first thermal oxide film 103a, a second polysilicon 104b deposited on the trench second thermal oxide film 103b, a third polysilicon 104c deposited on the trench third thermal oxide film 103c, a fourth polysilicon 104d deposited on the trench fourth thermal oxide film 103d, and a fifth polysilicon 104e deposited on the trench fifth thermal oxide film 103e . In the present embodiment, the first polysilicon 104a and the second polysilicon 104b are in contact with each other in the X direction, and a seam 110 extending in the Y direction is formed by the first polysilicon 104a and the second polysilicon 104b.
In the present embodiment, an annealing process is performed to promote rearrangement and/or rejoining of the polysilicon 104. As a result, the first polysilicon 104a and the second polysilicon 104b are jointed to each other in the X direction such that the seam 110 is strongly bonded at least on the side of the first main surface 101a . Although illustration is omitted, the cross section of the trench 71 has the same configuration as the cross section of the trench 51 except that the X direction is changed to the Y direction. The description thereof is omitted.
Next, as shown in
Next, as shown in
Next, as shown in
Next, as shown in
Next, as shown in
Next, as shown in
Next, as shown in
As a result, in the device region Ed, all adjacent exposed spaces are integrated to form a cavity 11 inside the first semiconductor wafer 101. In the cavity 11, the movable electrode 20 is in a floating state by being supported by the first support 15 with respect to the first peripheral wall 12. Similarly, in the cavity 11, the fixed electrode 30 is in a floating state by being supported by the second support 16 with respect to the second peripheral wall 13. Further, the isolator 50 is formed to protrude into the cavity 11 while traversing the first support 15 and the second support 16 in the Y direction and the Z direction, respectively.
Finally, as shown in
Next, a method of manufacturing the lid-side substrate assembly 3 will be described with reference to
The second semiconductor wafer 201 has a first main surface 201a and a second main surface 201b corresponding to the first main surface 90a and the second main surface 90b of the lid-side substrate 90, respectively. A metal film 203 is deposited over the entire first main surface 201a of the second semiconductor wafer 201 by, for example, a sputtering method. The metal film 203 is then patterned by photolithography and etching to form a bonding pad 93.
Next, as shown in
Next, as shown in
Next, as shown in
Next, a process of bonding the device-side substrate assembly 2 and the lid-side substrate assembly 3 will be described. As shown in
Next, as shown in
According to the MEMS sensor 1 and the manufacturing method thereof according to the embodiments of the present disclosure described above, the following effects may be obtained.
(1) A MEMS sensor 1 includes a conductive device-side substrate 10 including a cavity 11 in a thickness direction of the conductive device-side substrate 10, a sensor 5 including a movable electrode 20 and a fixed electrode 30 which are MEMS electrodes arranged in the cavity 11, a first support 15 and a second support 16 extending in an X direction toward the sensor 5 from a first peripheral wall 12 and a second peripheral wall 13 of the cavity 11 and connected to the sensor 5 to support the sensor 5, and an isolator 50 configured to traverse the first support 15 and the second support 16 in a Y direction in a plan view to electrically insulate the first support 15 and the second support 16 in an X direction. The isolator 50 includes a trench 51 recessed in the thickness direction with respect to the device-side substrate 10, trench insulating layers 52 formed on inner wall surfaces of the trench 51, and trench joining layers 53 further formed on the trench insulating layers 52 and including portions facing each other in the X direction and at least partially joined to each other in the X direction.
According to the embodiments of the present disclosure, in the isolator 50, the seam 110 between the trench insulating layers 52 (a trench first thermal oxide film 103a and a trench second thermal oxide film 103b) facing each other in the X direction is joined in the X direction by the trench joining layers 53. Therefore, it is possible to suppress breakage of the isolator 50 along the seam 110.
(2) The trench insulating layers 52 may be easily formed of silicon oxide films.
(3) The trench joining layers 53 may be easily formed of polysilicon.
(4) The trench joining layers 53 are joined at least on the side of a first main surface 101a of a first semiconductor wafer 101 in the trench 51. According to the embodiments of the present disclosure, the seam 110 is joined at least in the X direction on the side of an opening of the trench 51. Therefore, it is possible to further suppress breakage of the isolator 50 along the seam, as compared with a case where the seam is joined on the bottom side.
(5) The MEMS sensor 1 further includes a lid-side substrate 90 connected to the device-side substrate 10 to form an accommodation space Z in which the sensor 5 is accommodated between the device-side substrate 10 and the lid-side substrate 90, a pad 40 configured to take out an electric signal from the sensor 5 outside the accommodation space Z, and a conductive path 60 configured to electrically connect the sensor 5 and the pad 40. The conductive path 60 includes an inner conductive path 70 embedded in the device-side substrate 10. According to the embodiments of the present disclosure, the conductive path 60 may be formed on the device-side substrate 10 while suppressing an increase in thickness.
(6) The inner conductive path 70 includes a trench 71 recessed in the thickness direction with respect to the device-side substrate 10, trench insulating layers 72 formed on inner wall surfaces of the trench 71, and trench conductive layers 73 further formed on the trench insulating layers 72. According to the embodiments of the present disclosure, the inner conductive path 70 can be easily formed.
(7) The trench insulating layers 72 may be easily formed of silicon oxide films.
(8) The trench conductive layers 73 may be easily formed of conductive polysilicon.
(9) The inner conductive path 70 has a surface flush with a surface of the device-side substrate 10 in the thickness direction of the device-side substrate 10. The MEMS sensor further includes a main insulating layer 17 formed over the first main surface 10a of the device-side substrate 10 and the surface of the inner conductive path 70, and a bonding layer 19 further formed on the main insulating layer 17 and bonded to the lid-side substrate 90. The inner conductive path 70 traverses the bonding layer 19 in a plan view. According to the embodiments of the present disclosure, the surface extending over the device-side substrate 10 and the inner conductive path 70 may be formed to be flat. Therefore, the main insulating layer 17 may be further formed to be flat over the first main surface 10a of the device-side substrate 10 and the inner conductive path 70. Further, it is easy to form the bonding layer 19 to be flat on the flat main insulating layer 17. Accordingly, the lid-side substrate 90 may be easily bonded to the device-side substrate 10 via the flat bonding layer 19. Moreover, even when the main insulating layer 17 is laminated over the inner conductive paths 70 adjacent to each other in the Y direction, passivation coverage for the inner conductive paths 70 of the main insulating layer 17 is improved because the inner conductive paths 70 are formed to be flush with the first main surface 10a of the device-side substrate 10 as described above. Accordingly, it is easy to prevent conduction between the adjacent inner conductive paths 70.
(10) The inner conductive path 70 extends from a position facing an inside of the accommodation space Z to a position facing an outside of the accommodation space Z in a plan view. According to the embodiments of the present disclosure, the inner conductive path 70 may suppress unevenness of the surface of the device-side substrate 10 in the boundary region between the inside and the outside of the accommodation space Z, thus causing the lid-side substrate 90 to be easily bonded to the surface.
(11) The inner conductive path 70 extends in the X direction traversing the bonding layer 19 and includes inner wall surfaces facing each other in the Y direction. At least portions of the trench conductive layers 73 further formed on the trench insulating layers 72 formed on the opposing inner wall surfaces are joined in the Y direction. According to the embodiments of the present disclosure, the inner conductive path 70 has a seam between the trench insulating layers 72 facing each other in the Y direction, and the seam is joined in the Y direction by the trench conductive layer 73. Therefore, it is possible to suppress breakage of the inner conductive path 70 along the seam.
(12) The trench conductive layer 73 is joined at least on the side of the first main surface 10a of the device-side substrate 10 in the trench 71. According to the embodiments of the present disclosure, the seam is joined on the side of an opening of the trench 71. Therefore, it is possible to further suppress breakage of the inner conductive path 70 along the seam, as compared with the case where the seam is joined on the bottom side.
(13) The pad 40 is formed on the main insulating layer 17, and the MEMS sensor further includes a pad wiring 62 formed on the main insulating layer 17 and extending from a pad wiring first end 62a, which is formed on the main insulating layer 17 and connected to the pad 40, to a pad wiring second end 62b facing the inner conductive path 70 in a plan view, and a third contact (pad wiring contact) 83 penetrating the main insulating layer 17 to electrically connect the pad wiring second end 62b and the inner conductive path 70. According to the embodiments of the present disclosure, the inner conductive path 70 embedded in the device-side substrate 10 and the pad 40 formed on the surface of the device-side substrate 10 may be electrically connected via the main insulating layer 17.
(14) The MEMS sensor 1 further includes a first support 15 and a second support 16 extending in the X direction toward the sensor 5 from the first peripheral wall 12 and the second peripheral wall 13 of the cavity 11 and connected to the sensor 5 to support the sensor 5, an isolator 50 configured to traverse the first support 15 and the second support 16 in the Y direction to electrically insulate the first support 15 and the second support 16 in the X direction in a plan view, a MEMS electrode wiring 61 formed on the main insulating layer 17 and extending from a MEMS electrode wiring first end 61a facing closer to the sensor 5 than the isolator 50 in the first support 15 and the second support 16 in a plan view to a MEMS electrode wiring second end 61b facing the inner conductive path 70, a first contact 81 (MEMS electrode wiring first contact) penetrating the main insulating layer 17 to electrically connect a portion of the first support 15 and the second support 16 located on the side of the sensor 5 to the MEMS electrode wiring first end 61a, and a second contact 82 (MEMS electrode wiring second contact) penetrating the main insulating layer 17 to electrically connect the inner conductive path 70 to the MEMS electrode wiring second end 61b . According to the embodiments of the present disclosure, the inner conductive path 70 embedded in the device-side substrate 10 and the MEMS electrode wiring 61 formed on the side of the first main surface 10a of the device-side substrate 10 via the main insulating layer 17 may be electrically connected to each other.
(15) A MEMS sensor manufacturing method includes: forming a trench 51 traversing in a Y direction a conductive path extending in an X-direction from a sensor 5 including a movable electrode 20 and a fixed electrode 30, which are MEMS electrodes, on a device-side substrate 10; forming trench insulating layers 52 on inner wall surfaces of the trench 51; forming trench joining layers 53 on the trench insulating layers 52 to be at least partially joined to each other in the X direction; and bonding a lid-side substrate 90 to the device-side substrate 10 to cover the sensor 5. According to the embodiments of the present disclosure, in the isolator 50, the seam 110 between the trench insulating layers 52 (a trench first thermal oxide film 103a and a trench second thermal oxide film 103b) facing each other in the X direction is joined in the X direction by the trench joining layers 53. Therefore, it is possible to suppress breakage of the isolator 50 along the seam 110.
(16) The trench joining layers 53 are annealed. This makes it easier to join the trench joining layers 53 together and makes it possible to further prevent breakage of the isolator 50 along the seam 110.
(17) A MEMS sensor manufacturing method includes: forming a trench 71 extending in an X direction on a device-side substrate 10 at a part of a conductive path extending in the X direction to a pad 40 configured to take out an electric signal from a sensor 5 including a movable electrode 20 and a fixed electrode 30, which are MEMS electrodes; forming trench insulating layers 72 on inner wall surfaces of the trench 71; forming trench conductive layers 73 on the trench insulating layers 72; and bonding a lid-side substrate 90 to the device-side substrate 10 to cover the sensor 5. According to the embodiments of the present disclosure, the conductive path 60 may be formed on the device-side substrate 10 while suppressing an increase in thickness.
(18) When manufacturing the device-side substrate 10, the trenches 51 and 71 are simultaneously formed on the first semiconductor wafer 101, the trench insulating layers 52 and 72 are simultaneously formed on the inner wall surfaces of the trenches 51 and 71, and the trench joining layers 53 and the trench conductive layers 73 are simultaneously formed on the trench insulating layers 52 and 72, thereby forming the isolator 50 and the inner conductive path 70 simultaneously. According to the embodiments of the present disclosure, the isolator 50 and the inner conductive path 70 are formed simultaneously, and therefore the number of steps may be reduced as compared with the case where the isolator 50 and the inner conductive path 70 are formed in separate steps. As a result, the MEMS sensor 1 may be efficiently manufactured, and manufacturing cost may be reduced because, for example, it is possible to integrate masks used when forming the isolator 50 and the inner conductive path 70 by etching respectively.
The present disclosure is not limited to the above-described embodiments, and various modifications may be made.
In the above-described embodiments of the present disclosure, the annealing process is performed after the polysilicon 104 is deposited by the CVD method. However, the annealing process may not be performed when the portions of the polysilicon 104 facing each other are bonded to each other in the trenches 51 and 71.
According to the above-described embodiments of the present disclosure, in the isolator, the seam between the insulating layers facing each other in the first direction is joined in the first direction by the joining layer. Therefore, it is possible to suppress breakage of the isolator along the seam.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosures. Indeed, the embodiments described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and changes in the form of the embodiments described herein may be made without departing from the spirit of the disclosures. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the disclosures.
Number | Date | Country | Kind |
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2021-194811 | Nov 2021 | JP | national |