MEMS sensor and method for manufacturing MEMS sensor

Abstract

To suppress the intrusion of a eutectic material into a sensor element in a MEMS sensor in which the sensor element is sealed by eutectic bonding.SOLUTION: An MEMS sensor 1 includes a first substrate 10 having a sensor element 2, and a second substrate 20 bonded to the first substrate 10. A bonding portion 6 that seals the sensor element 2 is formed between the first substrate 10 and the second substrate 20, and an inner insulating portion 14 and an outer insulating portion 15 are formed on the first substrate 10, respectively, on the inside and outside of the bonding portion 6. The outer insulating portion 15 extends farther from the bonding portion 6 than the inner insulating portion 14. The bonding portion 6 is a eutectic bonding portion formed by eutectic bonding of Al and Ge.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a MEMS sensor and a method for manufacturing the MEMS sensor.

Background Art

[0002] A MEMS (Micro Electro Mechanical System) sensor manufactured using semiconductor microfabrication technology is known. Patent Document 1 discloses a MEMS sensor in which a second substrate is bonded to a first substrate having a sensor element, and a bonding portion made of AlGe is formed between the first substrate and the second substrate so as to seal the sensor element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When Al and Ge are eutectically bonded by heating to a predetermined temperature in a state where an Al layer formed on a first substrate having a sensor element and a Ge layer formed on a second substrate are pressed, a part of the eutectic material may enter the sensor element, which may reduce the reliability of the sensor.

[0005] An object of the present disclosure is to suppress the intrusion of the eutectic material into the sensor element in a MEMS sensor in which the sensor element is sealed by eutectic bonding.

Means for Solving the Problems

[0006] The present disclosure provides a MEMS sensor, comprising a first substrate having a sensor element and a second substrate bonded to the first substrate, a bonding portion for sealing the sensor element is formed between the first substrate and the second substrate, an inner insulating portion and an outer insulating portion are formed on the first substrate inside and outside the bonding portion, the outer insulating portion extends away from the bonding portion more than the inner insulating portion, and the bonding portion is a eutectic bonding portion in which Al and Ge are eutectically bonded.

[0007] According to the present disclosure, when a eutectic bonding portion in which Al and Ge are eutectically bonded is formed between the first substrate and the second substrate so as to seal the sensor element, the outer insulating portion on the first substrate extends away from the bonding portion more than the inner insulating portion on the first substrate. Thereby, when the Al layer on the first substrate and the Ge layer on the second substrate are bonded to form a eutectic bonding portion, if Al layers are formed on the outer insulating portion and the inner insulating portion respectively, since there is more Al on the outer insulating portion than on the inner insulating portion, the eutectic material of Al and Ge protruding from the eutectic bonding portion protrudes more on the outer insulating portion than on the inner insulating portion, and it is possible to suppress the intrusion of the eutectic material into the sensor element.

[0008] Further, the present disclosure provides a method for manufacturing a MEMS sensor, in which a portion to be sealed is formed of an Al layer on a first substrate having a sensor element, an inner insulating portion and an outer insulating portion are formed inside and outside the portion to be sealed on the first substrate respectively, a sealing portion bonded to the portion to be sealed is formed of a Ge layer on a second substrate, the portion to be sealed and the sealing portion are bonded by eutectic bonding of Al and Ge to form a bonding portion for sealing the sensor element between the first substrate and the second substrate, and the outer insulating portion extends away from the bonding portion more than the inner insulating portion.

[0009] According to the present disclosure, when a joint portion in which Al and Ge are eutectically bonded is formed between a first substrate and a second substrate so as to seal a sensor element, an outer insulating portion on the first substrate extends away from the joint portion more than an inner insulating portion on the first substrate. Thus, when an Al layer is formed on each of the outer insulating portion and the inner insulating portion when the Al layer on the first substrate and the Ge layer on the second substrate are joined to form a eutectic joint portion, since there is more Al on the outer insulating portion than on the inner insulating portion, the eutectic material of Al and Ge that protrudes from the eutectic joint portion protrudes more onto the outer insulating portion than onto the inner insulating portion, and it is possible to suppress the intrusion of the eutectic material into the sensor element.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0012] FIG. 1 is a schematic plan view of a MEMS sensor according to a first embodiment of the present disclosure. As shown in FIG. 1, the MEMS sensor 1 according to the first embodiment of the present disclosure has, as a sensor element 2, although not limited thereto, a capacitive acceleration sensor element in a sensor region.

[0013] The MEMS sensor 1 includes a first substrate assembly 11 including a first substrate 10 as a device-side substrate having the sensor element 2, and a second substrate assembly 21 including a second substrate 20 as a lid-side substrate joined to the first substrate 10 so as to seal the sensor element 2 under vacuum or a predetermined pressure. The MEMS sensor 1 is manufactured by processing the first substrate 10 and the second substrate 20 using semiconductor microfabrication technology.

[0014] Hereinafter, a predetermined direction along the surfaces of the first substrate 10 and the second substrate 20 is defined as the X direction, a direction orthogonal to the X direction is defined as the Y direction, and a thickness direction of the first substrate 10 and the second substrate 20 orthogonal to the X direction and the Y direction is defined as the Z direction. In FIG. 1, a MEMS sensor 1 in which the second substrate 20 is joined above the first substrate 10 in the Z direction is shown.

[0015] The sensor element 2 has a first sensor element 2a and a second sensor element 2b, which are well-known capacitive acceleration sensor elements. The first sensor element 2a is configured to detect acceleration in the X direction. The second sensor element 2b is configured to detect acceleration in the Y direction.

[0016] The sensor element 2 is disposed inside a joint portion 6 formed between the first substrate 10 and the second substrate 20 when the second substrate 20 is joined to the first substrate 10. A space portion 7 in which the sensor element 2 is sealed is formed inside the joint portion 6. The space portion 7 is defined by the first substrate 10, the second substrate 20, and the joint portion 6.

[0017] The first substrate 10 is provided with a plurality of pad portions 3. The pad portions 3 are connected to external electronic components or the like. The pad portions 3 are adapted to input an electrical signal to the sensor element 2 or output the electrical signal of the sensor element 2. A wiring electrically connected to the sensor element 2 and a wiring electrically connected to the first substrate 10 are connected to the pad portions 3.

[0018] FIG. 2 is a cross-sectional view of the MEMS sensor taken along line II-II of FIG. 1. As shown in FIG. 2, the first substrate assembly 11 includes a first substrate 10 having a first main surface 10a that is the front surface and a second main surface 10b that is the back surface on the opposite side of the first main surface 10a. The first substrate 10 is formed in a rectangular shape having two sides extending in the X direction and two sides extending in the Y direction in plan view. A single-crystalline silicon substrate is used as the first substrate 10.

[0019] The first substrate 10 has a cavity 12 that is partially exposed on the first main surface 10a corresponding to the sensor element 2. The cavity 12 is formed by being recessed in a substantially rectangular parallelepiped shape in the thickness direction of the first substrate 10 from the first main surface 10a, and has a bottom wall portion 12a and side wall portions 12b extending in the thickness direction of the first substrate 10 from the bottom wall portion 12a.

[0020] The sensor element 2 has an electrode 13 that is movably disposed in the cavity 12, and the electrode 13 includes a fixed electrode 13a and a movable electrode 13b that is relatively movable with respect to the fixed electrode 13a. When an acceleration acts on the sensor element 2, the capacitance between the fixed electrode 13a and the movable electrode 13b changes. The MEMS sensor 1 is adapted to detect the acceleration by taking out the change in the capacitance between the fixed electrode 13a and the movable electrode 13b as an electrical signal.

[0021] The second substrate assembly 21 includes a second substrate 20 having a first main surface 20a that is the front surface and a second main surface 20b that is the back surface on the opposite side of the first main surface 20a. The second substrate 20 is formed in a rectangular shape having two sides extending in the X direction and two sides extending in the Y direction in plan view, and is formed shorter in the X direction than the first substrate 10. A single-crystalline silicon substrate is used as the second substrate 20.

[0022] As described above, the second substrate 20 is joined to the first substrate 10, and a joint portion 6 is formed between the first substrate 10 and the second substrate 20. The joint portion 6 is formed over the entire periphery of the sensor element 2 so as to seal the sensor element 2, and is formed in an annular shape in a substantially square frame shape in plan view.

[0023] The joint portion 6 is a eutectic joint portion 6 in which Al and Ge are eutectically joined. A portion to be sealed is formed by an Al layer on the first substrate 10, a seal portion 9 is formed by a Ge layer on the second substrate 20, and the joint portion 6 is formed by joining the portion to be sealed and the seal portion by eutectic joining of Al and Ge.

[0024] FIG. 3 is a cross-sectional view of the MEMS sensor before joining the first substrate and the second substrate. As shown in FIG. 3, before joining the first substrate 10 and the second substrate 20, a portion 8 to be sealed is formed around the sensor element 2 on the first substrate 10. The portion 8 to be sealed is formed in an annular shape in a substantially square frame shape in plan view and is formed in a substantially rectangular cross-section. The portion 8 to be sealed is formed by an Al layer by a sputtering method or the like. Note that the portion 8 to be sealed may be formed on a protective layer or the like formed on the first substrate 10.

[0025] On the second substrate 20, a seal portion 9 is formed corresponding to the portion 8 to be sealed. The seal portion 9 is formed in an annular shape in a substantially square frame shape in plan view and is formed in a substantially rectangular cross-section. The seal portion 9 is formed by a Ge layer by a vapor deposition method or the like.

[0026] In the MEMS sensor 1, an inner insulating portion 14 and an outer insulating portion 15 are respectively disposed inside and outside the portion 8 to be sealed formed on the first substrate 10. The inner insulating portion 14 is disposed in an annular shape in a substantially square frame shape in plan view on the inner peripheral side of the portion 8 to be sealed. The outer insulating portion 15 is disposed in an annular shape in a substantially square frame shape in plan view on the outer peripheral side of the portion 8 to be sealed. The inner insulating portion 14 and the outer insulating portion 15 are each formed by a silicon oxide film by a CVD method or the like.

[0027] The inner insulating portion 14 has a first portion 14a extending inward from the sealed portion 8, a second portion 14b extending upward along the sealed portion 8 from the side of the first portion 14a on the sealed portion side, and a third portion 14c extending outward from the upper side of the second portion 14b to cover the sealed portion 8.

[0028] The outer insulating portion 15 has a first portion 15a extending outward from the sealed portion 8, a second portion 15b extending upward along the sealed portion 8 from the side of the first portion 15a on the sealed portion side, and a third portion 15c extending inward from the upper side of the second portion 15b to cover the sealed portion 8.

[0029] The second portion 15b and the third portion 15c of the outer insulating portion 15 are formed symmetrically with the second portion 14b and the third portion 14c of the inner insulating portion 14 with the sealed portion 8 therebetween. The first portion 15a of the outer insulating portion 15 extends away from the sealed portion 8 more than the first portion 14a of the inner insulating portion 14, and is formed with a larger dimension in a direction orthogonal to the extending direction of the sealed portion 8. The third portion 15c of the outer insulating portion 15 and the third portion 14c of the inner insulating portion 14 are formed to be spaced apart so that the sealing portion 9 is joined to the sealed portion 8.

[0030] In the MEMS sensor 1, protective layers 17 are also formed on the inner insulating portion 14 and the outer insulating portion 15, respectively. The protective layer 17 is formed of an Al layer by a sputtering method or the like. The protective layer 17 is formed in the same shape as the inner insulating portion 14 and the outer insulating portion 15 in plan view.

[0031] When the second substrate 20 is joined to the first substrate 10, the first substrate assembly 11 and the second substrate assembly 21 are overlapped and heated to a predetermined temperature, such as 480 degrees, for a predetermined time, such as 10 minutes, while a predetermined pressure is applied. The sealed portion 8 and the sealing portion 9 come into contact with each other, and Al and Ge are melted by a eutectic reaction between the Al layer of the sealed portion 8 and the Ge layer of the sealing portion 9. The eutectic of the melted Al and Ge is cooled to a solid phase to form the eutectic joint portion 6.

[0032] As shown in Fig. 2, the eutectic joint 6 refers to the portion where the portion to be sealed 8 and the seal portion 9 are joined. The first portion 14a of the inner insulating portion 14 extends inside the joint 6, the second portion 14b extends upward along the joint 6 from the joint side of the first portion 14a, and the third portion 14c extends outward from the upper side of the second portion 14b so as to cover the joint 6. The first portion 15a of the outer insulating portion 15 extends outside the joint 6, the second portion 15b extends upward along the joint 6 from the joint side of the first portion 15a, and the third portion 15c extends inward from the upper side of the second portion 15b so as to cover the joint 6.

[0033] When Al and Ge melt by eutectic reaction, a part of the eutectic of Al and Ge reacts with the Al layer which is the protective layer 17 formed on the inner insulating portion 14 and the outer insulating portion 15 arranged inside and outside the joint 6 respectively, and protrudes onto the inner insulating portion 14 and the outer insulating portion 15, and will exist between the inner insulating portion 14 and the outer insulating portion 15 and the second substrate 20. In the present embodiment, the eutectic material 6b between the outer insulating portion 15 and the second substrate 20 can be made more than the eutectic material 6a between the inner insulating portion 14 and the second substrate 20.

[0034] Thus, in the MEMS sensor 1, a joint 6 for sealing the sensor element 2 is formed between the first substrate 10 and the second substrate 20, and an inner insulating portion 14 and an outer insulating portion 15 are formed on the first substrate 10 inside and outside the joint 6 respectively, and the outer insulating portion 15 extends so as to be farther from the joint 6 than the inner insulating portion 14.

[0035] When the Al layer on the first substrate 10 and the Ge layer on the second substrate 20 are joined to form the eutectic joint 6, when the Al layer is formed on the outer insulating portion 15 and the inner insulating portion 14 respectively, since there is more Al on the outer insulating portion 15 than on the inner insulating portion 14, the eutectic material of Al and Ge protruding from the eutectic joint 6 protrudes more onto the outer insulating portion 15 than onto the inner insulating portion 14, and it is possible to suppress the intrusion of the eutectic material into the sensor element 2.

[0036] FIG. 9 is a cross-sectional view of a MEMS sensor in which an inner insulating portion and an outer insulating portion are symmetrically formed. FIG. 10 is a cross-sectional view of the MEMS sensor before bonding the first substrate and the second substrate. Also in the MEMS sensor 101 shown in FIGS. 9 and 10, as shown in FIG. 10, before bonding the first substrate 10 and the second substrate 20, a sealed portion 8 made of an Al layer is formed on the first substrate 10, and an inner insulating portion 14 and an outer insulating portion 115 are formed inside and outside the sealed portion 8, respectively. An Al layer is formed as a protective layer 17 on the inner insulating portion 14 and the outer insulating portion 115, respectively. Further, a sealing portion 9 made of a Ge layer is formed on the second substrate 20.

[0037] In the MEMS sensor 101, the inner insulating portion 14 and the outer insulating portion 115 are symmetrically formed in a direction perpendicular to the extending direction of the joint portion 6, and the protective layer 17 formed on the inner insulating portion 14 and the outer insulating portion 115 is also symmetrically formed in a direction perpendicular to the extending direction of the joint portion 6.

[0038] In this case, when the sealing portion 9 is bonded to the sealed portion 8 by eutectic bonding, as shown in FIG. 9, a part 106a, 106b of the eutectic of Al and Ge protrudes from the eutectic joint portion 6 of Al and Ge onto the inner insulating portion 14 and the outer insulating portion 15, and there is a risk that the eutectic material will penetrate into the sensor element 2.

[0039] In the MEMS sensor 1 according to the present embodiment, since the outer insulating portion 15 extends farther from the joint portion 6 than the inner insulating portion 14, the eutectic material protruding from the eutectic joint portion 6 protrudes more onto the outer insulating portion 15 than onto the inner insulating portion 14, and it is possible to suppress the eutectic material from penetrating into the sensor element 2.

[0040] Next, a method for manufacturing the MEMS sensor 1 will be described. FIG. 4 is a schematic plan view of the first substrate assembly and the second substrate assembly. As shown in FIG. 4, the MEMS sensors 1 are arranged in a matrix in a state where the first substrate assembly 11 having the first substrate 10 and the second substrate assembly 21 having the second substrate 20 are overlapped and bonded.

[0041] The MEMS sensor 1 is cut out by dicing with a dicing blade along the lines L1 and L2 set in a grid pattern, respectively. Then, it is cut by dicing along the line L3, and the portion facing the pad portion 3 of the second substrate assembly 21 is removed, and the MEMS sensor 1 is manufactured.

[0042] FIG. 5 is a diagram for explaining a manufacturing method of the first substrate assembly. FIG. 6 is a diagram for explaining a manufacturing method of the second substrate assembly. In the manufacture of the MEMS sensor 1, a first substrate 10 which is a silicon substrate and a second substrate 20 which is a silicon substrate bonded to the first substrate 10 so as to seal the sensor element 2 are prepared.

[0043] As shown in FIG. 5, a sensor element 2 is formed on the first substrate 10. Also, on the first substrate 10, a portion to be sealed 8 is formed by an Al layer by a sputtering method or the like over the entire periphery of the sensor element 2. After the formation of the portion to be sealed 8, an inner insulating portion 14 and an outer insulating portion 15 are formed by a silicon oxide film by a CVD method or the like, and a protective layer 17 by an Al layer is formed on the inner insulating portion 14 and the outer insulating portion 15 by a sputtering method or the like. Also, a pad portion 3 and wirings are formed on the first substrate 10, and the first substrate assembly 11 is manufactured.

[0044] As shown in FIG. 6, on the second substrate 20, a sealing portion 9 joined to the portion to be sealed 8 is formed by a Ge layer by a vapor deposition method or the like, and the second substrate assembly 21 is manufactured. The sealing portion 9 is formed to be smaller in dimension in a direction orthogonal to the extending direction of the portion to be sealed 8 than the portion to be sealed 8 so as to contact the exposed portion between the inner insulating portion 14 and the outer insulating portion 15 in the portion to be sealed 8.

[0045] After manufacturing the first substrate assembly 11 and the second substrate assembly 21, as shown in FIG. 3, the second substrate assembly 21 is disposed on the first substrate assembly 11. Then, as shown in FIG. 2, a seal portion 9 is joined to the portion to be sealed 8, and the second substrate 20 is joined by eutectic bonding so as to seal the sensor element 2 to the first substrate 10. Thereafter, the first substrate assembly 11 and the second substrate assembly 21 are cut by dicing along lines L1, L2, and L3, and the MEMS sensor 1 is manufactured.

[0046] When Al and Ge are eutectically bonded between the first substrate 10 and the second substrate 20 to form a joint portion 6, the outer insulating portion 15 on the first substrate 10 extends away from the joint portion 6 more than the inner insulating portion 14 on the first substrate 10. Thus, when Al layers are formed on the outer insulating portion 15 and the inner insulating portion 14, respectively, since there is more Al on the outer insulating portion 15 than on the inner insulating portion 14, the eutectic material of Al and Ge protruding from the eutectic joint portion 6 protrudes more onto the outer insulating portion 15 than onto the inner insulating portion 14, and it is possible to suppress the intrusion of the eutectic material into the sensor element 2.

[0047] In the present embodiment, the inner insulating portion 14 has a first portion 14a, a second portion 14b, and a third portion 14c, and the outer insulating portion 15 has a first portion 15a, a second portion 15b, and a third portion 15c. However, the inner insulating portion 14 may have the first portion 14a and the second portion 14b without having the third portion 14c, and the outer insulating portion 15 may have the first portion 15a and the second portion 15b without having the third portion 15c.

[0048] FIG. 7 is a cross-sectional view of a MEMS sensor according to a second embodiment of the present disclosure. FIG. 8 is a cross-sectional view of the MEMS sensor before joining the first substrate and the second substrate. The MEMS sensor 51 according to the second embodiment is different from the MEMS sensor 1 according to the first embodiment in the outer insulating portion, and description of the same configuration will be omitted.

[0049] As shown in FIG. 7, also for the MEMS sensor 51, a joint portion 6 that seals the sensor element 2 is formed between the first substrate 10 and the second substrate 20, and the joint portion 6 is a eutectic joint portion 6 in which Al and Ge are eutectically joined. Further, an inner insulating portion 14 and an outer insulating portion 55 that are disposed inside and outside the joint portion 6 are formed on the first substrate 10, and the outer insulating portion 55 extends so as to be farther from the joint portion 6 than the inner insulating portion 14.

[0050] As shown in FIG. 8, the inner insulating portion 14 of the MEMS sensor 51 is formed in the same manner as the inner insulating portion 14 of the MEMS sensor 1. A protective layer 17 is formed of an Al layer on the inner insulating portion 14, and the protective layer 17 is formed in the same shape as the inner insulating portion 14 in plan view.

[0051] In the present embodiment, the outer insulating portion 55 of the MEMS sensor 51 has only a first portion 15a that is separated from the portion to be sealed 8 and extends outside the portion to be sealed 8. Unlike the outer insulating portion 15, the outer insulating portion 55 does not have a second portion 15b that extends upward along the portion to be sealed 8 from the side of the portion to be sealed 8 of the first portion 15a and a third portion 15c that extends inward from above the second portion 15b so as to cover the portion to be sealed 8. Also for the MEMS sensor 51, a protective layer 17 is formed of an Al layer on the outer insulating portion 55, and the protective layer 17 is formed in the same shape as the outer insulating portion 55 in plan view.

[0052] Also for the MEMS sensor 51, when the second substrate 20 is joined to the first substrate 10, the portion to be sealed 8 and the seal portion 9 come into contact with each other, and Al and Ge are melted by a eutectic reaction between the Al layer of the portion to be sealed 8 and the Ge layer of the seal portion 9. The eutectic of the melted Al and Ge is cooled to become a solid phase, and the eutectic joint portion 6 is formed.

[0053] As shown in FIG. 7, the eutectic joint 6 refers to a portion where the portion to be sealed 8 and the seal portion 9 are joined. The first portion 14a of the inner insulating portion 14 extends inside the joint 6, the second portion 14b extends upward along the joint 6 from the joint side of the first portion 14a, and the third portion 14c extends outward from the upper side of the second portion 14b so as to cover the joint 6. The first portion 15a of the outer insulating portion 55 extends outside the joint 6 away from the joint 6.

[0054] When Al and Ge are melted by a eutectic reaction, a part of the eutectic of Al and Ge reacts with the Al layer which is the protective layer 17 formed on the inner insulating portion 14 and the outer insulating portion 55 disposed inside and outside the joint 6 respectively, and protrudes onto the inner insulating portion 14 and the outer insulating portion 55, and will exist between the inner insulating portion 14 and the outer insulating portion 55 and the second substrate 20. Also in this embodiment, the eutectic material 106b between the outer insulating portion 55 and the second substrate 20 can be made more than the eutectic material 106a between the inner insulating portion 14 and the second substrate 20. In particular, since the outer insulating portion 55 has only the first portion 15a and is provided away from the joint 6, the eutectic of the melted Al and Ge easily moves to the outer insulating portion 55 side.

[0055] In this way, also for the MEMS sensor 51, a joint 6 for sealing the sensor element 2 is formed between the first substrate 10 and the second substrate 20, and an inner insulating portion 14 and an outer insulating portion 55 are formed inside and outside the joint 6 on the first substrate 10 respectively, and the outer insulating portion 55 extends away from the joint 6 more than the inner insulating portion 14.

[0056] When the Al layer on the first substrate 10 and the Ge layer on the second substrate 20 are joined to form the eutectic joint 6, when the Al layer is formed on the outer insulating portion 55 and the inner insulating portion 14 respectively, since there is more Al on the outer insulating portion 55 than on the inner insulating portion 14, the eutectic material of Al and Ge protruding from the eutectic joint 6 protrudes more onto the outer insulating portion 15 than onto the inner insulating portion 14, and it is possible to suppress the intrusion of the eutectic material into the sensor element 2.

[0057] In this embodiment, the inner insulating portion 14 has the first portion 14a, the second portion 14b, and the third portion 14c. However, the inner insulating portion 14 may have the first portion 14a and the second portion 14b without having the third portion 14c.

[0058] As described above, the MEMS sensor 1,51 according to this embodiment includes the first substrate 10 having the sensor element 2 and the second substrate 20 joined to the first substrate 10. A joint portion 6 that seals the sensor element 2 is formed between the first substrate 10 and the second substrate 20. An inner insulating portion 14 and outer insulating portions 15, 55 are respectively formed on the inner side and the outer side of the joint portion 6 on the first substrate 10. The outer insulating portions 15, 55 extend so as to be farther from the joint portion 6 than the inner insulating portion 14. The joint portion 6 is a eutectic joint portion 6 in which Al and Ge are eutectically joined.

[0059] When a eutectic joint portion 6 in which Al and Ge are eutectically joined is formed between the first substrate 10 and the second substrate 20 so as to seal the sensor element 2, the outer insulating portion 15 on the first substrate 10 extends so as to be farther from the joint portion 6 than the inner insulating portion 14 on the first substrate 10. As a result, when the Al layer on the first substrate 10 and the Ge layer on the second substrate 20 are joined to form the eutectic joint portion 6, when Al layers are respectively formed on the outer insulating portions 15, 55 and the inner insulating portion 14, since there is more Al on the outer insulating portions 15, 55 than on the inner insulating portion 14, the eutectic material of Al and Ge protruding from the eutectic joint portion 6 protrudes more onto the outer insulating portions 15, 55 than onto the inner insulating portion 14, and it is possible to suppress the intrusion of the eutectic material into the sensor element 2.

[0060] In addition, more eutectic material may exist between the outer insulating portions 15, 55 and the second substrate 20 than between the inner insulating portion 14 and the second substrate 20. Thereby, it is possible to suppress the intrusion of the eutectic material into the sensor element 2.

[0061] Further, the first substrate 10 and the second substrate 20 are silicon substrates, and the inner insulating portion 14 and the outer insulating portions 15, 55 can be formed of a silicon oxide film. Thus, by forming a silicon oxide film on the silicon substrate by a CVD method or the like, the inner insulating portion 14 and the outer insulating portion 15 can be formed relatively easily.

[0062] Also, the inner insulating portion 14 has a first portion 14a extending inward from the joint portion 6 and a second portion 14b extending upward along the joint portion 6 from the joint portion side of the first portion 14a. The outer insulating portion 15 has a first portion 15a extending outward from the joint portion 6 and a second portion 15b extending upward along the joint portion 6 from the joint portion side of the first portion 15a. The first portion 15a of the outer insulating portion 15 can extend away from the joint portion 6 more than the first portion 14a of the inner insulating portion 14. Thus, when Al layers are formed on the outer insulating portion 15 and the inner insulating portion 14 respectively, since there is more Al on the outer insulating portion 15 than on the inner insulating portion 14, the eutectic material protruding from the eutectic joint portion 6 can protrude onto the outer insulating portion 15 rather than onto the inner insulating portion 14.

[0063] Also, the inner insulating portion 14 has a third portion 14c extending outward so as to cover the joint portion 6 from above the second portion 14b of the inner insulating portion 14, and the outer insulating portion 15 can have a third portion 15c extending inward so as to cover the joint portion 6 from above the second portion 15b of the outer insulating portion 15. Thus, the third portion 14c of the inner insulating portion 14 and the third portion 15c of the outer insulating portion 15 can suppress the eutectic material from protruding from the eutectic joint portion 6.

[0064] Further, the inner insulating portion 14 has a first portion 14a extending inward from the joint portion 6 and a second portion 14b extending upward along the joint portion 6 from the joint portion side of the first portion 14a. The outer insulating portion 55 may have a first portion 15a extending outward from the joint portion 6 and spaced apart from the joint portion 6. Thereby, when the Al layer on the first substrate 10 and the Ge layer on the second substrate 20 are joined to form the eutectic joint portion 6, the eutectic material can be easily moved from the inside to the outside of the eutectic joint portion 6, and the intrusion of the eutectic material into the sensor element 2 can be suppressed.

[0065] Moreover, the manufacturing method of the MEMS sensor according to the present embodiment forms a portion to be sealed 8 on the first substrate 10 having the sensor element 2 with an Al layer, forms an inner insulating portion 14 and outer insulating portions 15 and 55 inside and outside the portion to be sealed 8 on the first substrate 10, respectively, forms a sealing portion 9 joined to the portion to be sealed 8 on the second substrate 20 with a Ge layer, and joins the portion to be sealed 8 and the sealing portion 9 by an eutectic bonding of Al and Ge to form a joint portion 6 that seals the sensor element 2 between the first substrate 10 and the second substrate 20. The outer insulating portion 15 extends so as to be farther from the joint portion 6 than the inner insulating portion 14.

[0066] When a joint portion 6 in which Al and Ge are eutectically joined is formed between the first substrate 10 and the second substrate 20 so as to seal the sensor element 2, the outer insulating portion 15 on the first substrate 10 extends so as to be farther from the joint portion 6 than the inner insulating portion 14 on the first substrate 10. Thereby, when an Al layer is formed on each of the outer insulating portions 15 and 55 and the inner insulating portion 14 when the Al layer on the first substrate 10 and the Ge layer on the second substrate 20 are joined to form the eutectic joint portion 6, since there is more Al on the outer insulating portion 15 than on the inner insulating portion 14, the eutectic material of Al and Ge protruding from the eutectic joint portion 6 protrudes more onto the outer insulating portion 15 than onto the inner insulating portion 14, and the intrusion of the eutectic material into the sensor element 2 can be suppressed.

[0067] Also, an Al layer can be formed on the inner insulating portion 14 and the outer insulating portion 15. Thus, when the Al layer is formed on the inner insulating portion 14 and the outer insulating portion 15, the eutectic material protruding from the joint portion 6 protrudes more onto the outer insulating portion 15 than onto the inner insulating portion 14, and it is possible to suppress the intrusion of the eutectic material into the sensor element 2.

[0068] The present disclosure is not limited to the illustrated embodiments, and various improvements and design changes are possible without departing from the gist of the present disclosure.

[0069] [Appendix 1] A first substrate having a sensor element, A second substrate joined to the first substrate, Comprising: A joint portion for sealing the sensor element is formed between the first substrate and the second substrate, An inner insulating portion and an outer insulating portion are formed on the first substrate, disposed inside and outside the joint portion, The outer insulating portion extends farther from the joint portion than the inner insulating portion, The joint portion is a eutectic joint portion in which Al and Ge are eutectically joined, MEMS sensor. [Appendix 2] There is more eutectic material between the outer insulating portion and the second substrate than between the inner insulating portion and the second substrate. The MEMS sensor according to Appendix 1. [Appendix 3] The first substrate and the second substrate are silicon substrates, The inner insulating portion and the outer insulating portion are formed of a silicon oxide film. The MEMS sensor according to Appendix 1 or Appendix 2. [Appendix 4] The inner insulating portion has a first portion extending inside the joint portion and a second portion extending upward along the joint portion from the joint portion side of the first portion. The outer insulating portion has a first portion extending outward from the joint portion and a second portion extending upward along the joint portion from the joint portion side of the first portion. The first portion of the outer insulating portion extends away from the joint portion farther than the first portion of the inner insulating portion. The MEMS sensor according to any one of Appendices 1 to 3. [Appendix 5] The inner insulating portion has a third portion extending outward from above the second portion of the inner insulating portion to cover the joint portion. The outer insulating portion has a third portion extending inward from above the second portion of the outer insulating portion to cover the joint portion. The MEMS sensor according to Appendix 4. [Appendix 6] The inner insulating portion has a first portion extending inward from the joint portion and a second portion extending upward along the joint portion from the joint portion side of the first portion. The outer insulating portion has a first portion extending away from the joint portion and extending outward from the joint portion. The MEMS sensor according to any one of Appendices 1 to 3. [Appendix 7] A sealed portion is formed of an Al layer on a first substrate having a sensor element. An inner insulating portion and an outer insulating portion are respectively formed inside and outside the sealed portion on the first substrate. A seal portion joined to the sealed portion is formed of a Ge layer on a second substrate. The sealed portion and the seal portion are joined by a eutectic bond of Al and Ge to form a joint portion for sealing the sensor element between the first substrate and the second substrate. The outer insulating portion extends away from the joint portion farther than the inner insulating portion. A method for manufacturing a MEMS sensor. [Appendix 8] An Al layer is formed on the inner insulating portion and the outer insulating portion. The method for manufacturing a MEMS sensor according to Appendix 7. [Appendix 9] The first substrate and the second substrate are silicon substrates, The inner insulating portion and the outer insulating portion are formed of a silicon oxide film, The method for manufacturing a MEMS sensor according to Appendix 7 or Appendix 8. [Appendix 10] The inner insulating portion has a first portion extending inward from the joint portion and a second portion extending upward along the joint portion from the joint portion side of the first portion, The outer insulating portion has a first portion extending outward from the joint portion and a second portion extending upward along the joint portion from the joint portion side of the first portion, The first portion of the outer insulating portion extends away from the joint portion more than the first portion of the inner insulating portion, The method for manufacturing a MEMS sensor according to any one of Appendices 7 to 9. [Appendix 11] The inner insulating portion has a third portion extending outward so as to cover the joint portion from above the second portion of the inner insulating portion, The outer insulating portion has a third portion extending inward so as to cover the joint portion from above the second portion of the outer insulating portion, The method for manufacturing a MEMS sensor according to Appendix 10. [Appendix 12] The inner insulating portion has a first portion extending inward from the joint portion and a second portion extending upward along the joint portion from the joint portion side of the first portion, The outer insulating portion has a first portion extending outward from the joint portion and spaced apart from the joint portion, The method for manufacturing a MEMS sensor according to any one of Appendices 7 to 9.

Explanation of Signs

[0070] 1,51 MEMS sensor 2 Sensor element 6 Joint portion 8 Portion to be sealed 9 Sealing portion 10 First substrate 14 Inner insulating portion The first part of the inner insulating portion 14a The second part of the inner insulating portion 14b The third part of the inner insulating portion 14c The outer insulating portions 15, 55 The first part of the outer insulating portion 15a The second part of the outer insulating portion 15b The third part of the outer insulating portion 15c The second substrate 20

Claims

1. A first substrate having a sensor element, A second substrate bonded to the first substrate, Comprising, A bonding portion for sealing the sensor element is formed between the first substrate and the second substrate, An inner insulating portion and an outer insulating portion are formed on the first substrate, disposed inside and outside the bonding portion, The outer insulating portion extends away from the bonding portion more than the inner insulating portion, The bonding portion is a eutectic bonding portion in which Al and Ge are eutectically bonded, A MEMS sensor.

2. More eutectic material exists between the outer insulating portion and the second substrate than between the inner insulating portion and the second substrate, The MEMS sensor according to Claim 1.

3. The first substrate and the second substrate are silicon substrates, The inner insulating portion and the outer insulating portion are formed of silicon oxide films, The MEMS sensor according to Claim 1.

4. The inner insulating portion has a first portion extending inside the bonding portion and a second portion extending upward along the bonding portion from the bonding portion side of the first portion, The outer insulating portion has a first portion extending outside the bonding portion and a second portion extending upward along the bonding portion from the bonding portion side of the first portion, The first portion of the outer insulating portion extends away from the bonding portion more than the first portion of the inner insulating portion, The MEMS sensor according to Claim 1.

5. The inner insulating portion has a third portion extending outward to cover the bonding portion from above the second portion of the inner insulating portion, The outer insulating portion has a third portion extending inward to cover the bonding portion from above the second portion of the outer insulating portion, The MEMS sensor according to Claim 4.

6. The inner insulating portion has a first portion extending inside the bonding portion and a second portion extending upward along the bonding portion from the bonding portion side of the first portion, The outer insulating portion has a first portion extending outside the bonding portion, spaced apart from the bonding portion, The MEMS sensor according to Claim 1.

7. A portion to be sealed is formed of an Al layer on a first substrate having a sensor element, An inner insulating portion and an outer insulating portion are respectively formed inside and outside the portion to be sealed on the first substrate, A sealing portion bonded to the portion to be sealed is formed of a Ge layer on a second substrate, Bond the sealed part and the sealing part by eutectic bonding of Al and Ge to form a bonding part that seals the sensor element between the first substrate and the second substrate. The outer insulating part extends away from the bonding part from the inner insulating part. A method for manufacturing a MEMS sensor.

8. An Al layer is formed on the inner insulating part and the outer insulating part. The method for manufacturing a MEMS sensor according to claim 7.

9. The first substrate and the second substrate are silicon substrates. The inner insulating part and the outer insulating part are formed of a silicon oxide film. The method for manufacturing a MEMS sensor according to claim 7.

10. The inner insulating part has a first part extending inward from the bonding part and a second part extending upward along the bonding part from the bonding part side of the first part. The outer insulating part has a first part extending outward from the bonding part and a second part extending upward along the bonding part from the bonding part side of the first part. The first part of the outer insulating part extends away from the bonding part from the first part of the inner insulating part. The method for manufacturing a MEMS sensor according to claim 7.

11. The inner insulating part has a third part extending outward from above the second part of the inner insulating part to cover the bonding part. The outer insulating part has a third part extending inward from above the second part of the outer insulating part to cover the bonding part. The method for manufacturing a MEMS sensor according to claim 10.

12. The inner insulating part has a first part extending inward from the bonding part and a second part extending upward along the bonding part from the bonding part side of the first part. The outer insulating part has a first part extending outward from the bonding part and spaced apart from the bonding part. The method for manufacturing a MEMS sensor according to claim 7.

Images