Physical quantity sensor and manufacturing method of physical quantity sensor

Abstract

To provide a physical quantity sensor capable of inhibiting a bonding member from being squeezed out, and suppressing yield reduction and reliability deterioration, and a manufacturing method of the physical quantity sensor.SOLUTION: The physical quantity sensor comprises: a substrate; a physical quantity detection element supported by the substrate and detecting a physical quantity; and a lid body bonded to the substrate via a bonding member and storing the physical quantity detection element between the substrate and the lid body. A surface of the substrate bonded to the bonding member is defined as a substrate bonding surface, and a surface of the lid body bonded to the bonding member is defined as a lid body bonding surface. In this case, at least one of the substrate bonding surface and the lid body bonding surface is provided with a pillar structure including a bottomed recess and a plurality of pillar parts provided erected on the bottom of the recess and arranged with gaps from each other. The bonding member intrudes into the recess.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a physical quantity sensor and a method for manufacturing a physical quantity sensor. [Background technology]

[0002] The composite sensor described in Patent Document 1 has a package that includes a substrate and a lid joined to the substrate via a joining member, and has a first housing section and a second housing section that are independently formed. The first housing section houses three acceleration sensor elements, and the second housing section houses three angular velocity sensor elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-169365 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned composite sensor, the joining material joining the substrate and the lid body easily protrudes into and out of the first and second housings, which can have adverse effects on surrounding components, such as contacting the acceleration sensor element or the angular velocity sensor element and causing these elements to stop functioning, or covering the terminals and making it difficult to electrically connect to an external device. [Means for solving the problem]

[0005] The physical quantity sensor of the present invention comprises a substrate and a physical quantity detection element supported on the base and detecting a physical quantity; a lid body that is joined to the base body via a joining member and that houses the physical quantity detection element between the lid body and the base body, a surface of the base that is joined to the joining member is defined as a base joining surface; When the surface of the lid body joined to the joining member is defined as a lid body joining surface, At least one of the base joining surface and the lid joining surface has a pillar structure formed thereon, the pillar structure having a bottomed recess and a plurality of column portions erected on the bottom surface of the recess and arranged at intervals from each other, and the joining member penetrates into the recess.

[0006] A method for manufacturing a physical quantity sensor of the present invention is a method for manufacturing a physical quantity sensor having a base that supports a physical quantity detection element that detects a physical quantity, and a lid that is joined to the base to accommodate the physical quantity detection element between the base and the lid, a pillar structure forming step of forming a pillar structure on at least one of the base joining surface and the lid joining surface, the pillar structure having a bottomed recess and a plurality of pillar portions erected on the bottom surface of the recess and arranged at intervals from each other, when a surface of the base that is joined to the lid is defined as a base joining surface and a surface of the lid that is joined to the base is defined as a lid joining surface; a bonding member placement step of placing a bonding member on at least one of the base bonding surface and the lid bonding surface; and a joining step of joining the base body and the lid body via the joining member. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a physical quantity sensor according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 10 is a plan view showing a modified example of the physical quantity sensor. [Figure 4] 2 is a cross section taken along line AA in FIG. 1, and is an enlarged cross section of the joint between the lid and the base. [Figure 5] 2 is a cross-sectional view taken along the line BB in FIG. 1, and is an enlarged cross-sectional view of the joint between the lid and the base. [Figure 6] FIG. 2 is a cross-sectional view of the pillar structure as seen from the positive side in the Z-axis direction. [Figure 7] FIG. 10 is a cross-sectional view showing a modified example of the pillar structure. [Figure 8] 1 is a flowchart showing a manufacturing process of a physical quantity sensor. [Figure 9] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 10] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 11] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 12] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 13] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 14] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 15] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 16] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 17] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 18] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 19] 10A to 10C are cross-sectional views for explaining a method for manufacturing a physical quantity sensor. [Figure 20] FIG. 10 is an enlarged cross-sectional view showing a joint portion between a lid and a base of a physical quantity sensor according to a second embodiment. [Figure 21] FIG. 10 is an enlarged cross-sectional view showing a state after the joining member arrangement step. [Figure 22] FIG. 10 is an enlarged cross-sectional view showing a modified example of the pillar structure. [Figure 23] FIG. 10 is an enlarged cross-sectional view showing a modified example of the pillar structure. [Figure 24] FIG. 10 is an enlarged cross-sectional view showing a modified example of the pillar structure. [Figure 25] FIG. 10 is an enlarged cross-sectional view showing a modified example of the pillar structure. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A physical quantity sensor and a method for manufacturing a physical quantity sensor according to the present invention will be described in detail below with reference to embodiments shown in the accompanying drawings.

[0009] First Embodiment FIG. 1 is a plan view showing a physical quantity sensor according to a first embodiment. FIG. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 3 is a plan view showing a modified example of the physical quantity sensor. FIG. 4 is a cross-sectional view taken along line AA in FIG. 1, and is an enlarged cross-sectional view of a joint between a lid body and a base body. FIG. 5 is a cross-sectional view taken along line BB in FIG. 1, and is an enlarged cross-sectional view of a joint between a lid body and a base body. FIG. 6 is a cross-sectional view of a pillar structure viewed from the positive side in the Z-axis direction. FIG. 7 is a cross-sectional view showing a modified example of the pillar structure. FIG. 8 is a flowchart showing manufacturing steps for a physical quantity sensor. FIGS. 9 to 19 are cross-sectional views for explaining a manufacturing method for a physical quantity sensor.

[0010] For ease of explanation, the second silicon oxide layer 2B is not shown in Figures 1 and 3. Each figure except for Figure 8 illustrates three mutually orthogonal axes: the X-axis, the Y-axis, and the Z-axis. Hereinafter, for ease of explanation, the direction along the X-axis, i.e., the direction parallel to the X-axis, will be referred to as the "X-axis direction," the direction along the Y-axis as the "Y-axis direction," and the direction along the Z-axis as the "Z-axis direction." The arrowhead side of each axis will also be referred to as the "plus side," and the opposite side as the "minus side." The positive side of the Z-axis will also be referred to as the "upper," and the negative side of the Z-axis will also be referred to as the "lower."

[0011] 1 and 2 is an acceleration sensor for detecting acceleration in the X-axis direction. Such physical quantity sensor 1 includes a base 3 and an acceleration detection element 4 as a physical quantity detection element, which are integrally formed by patterning an SOI (Silicon on Insulator) substrate 2 using a semiconductor process, a lid 5 joined to the base 3 via a joining member 6 and forming an airtight housing space S between the base 3 and the lid 5 for housing the acceleration detection element 4, and a wiring group 7 routed inside and outside the housing space S and electrically connected to the acceleration detection element 4.

[0012] As shown in FIG. 2, the SOI substrate 2 includes a first silicon layer 2A located above, a second silicon layer 2C located below, and a silicon oxide layer 2B interposed between the first silicon layer 2A and the second silicon layer 2C. In particular, the SOI substrate 2 of this embodiment is a cavity SOI substrate in which a recess 311 is formed in advance on the upper surface of the second silicon layer 2C. Of these three layers 2A, 2B, and 2C, the first silicon layer 2A is also called a device layer, the second silicon layer 2C is also called a handle layer, and the silicon oxide layer 2B is also called a BOX layer. The thickness of the first silicon layer 2A is approximately 200 μm to 300 μm, the thickness of the silicon oxide layer 2B is approximately 20 μm, and the thickness of the second silicon layer 2C is approximately 200 μm to 500 μm. However, the thicknesses of the layers 2A, 2B, and 2C are not particularly limited. An insulating layer 2D is formed on the upper surface of the SOI substrate 2. The insulating layer 2D is made of, for example, silicon oxide, and is formed by sputtering.

[0013] ≪Base 3≫ 2, the base 3 is formed from a stack of an insulating layer 2D, a first silicon layer 2A, a silicon oxide layer 2B, and a second silicon layer 2C. Such a base 3 has a cavity portion 31 formed from the two lower layers, i.e., the second silicon layer 2C and the silicon oxide layer 2B, and a frame portion 32 formed from the two upper layers, i.e., the insulating layer 2D and the first silicon layer 2A, and disposed above the cavity portion 31.

[0014] The cavity 31 has a recess 311 that opens to its upper surface. The recess 311 overlaps with the acceleration detection element 4 in a plan view of the substrate 3, that is, in a plan view from the Z-axis direction, and functions as a relief portion that prevents contact between the base 3 and the acceleration detection element 4. On the other hand, the frame 32 is disposed so as to surround the entire periphery of the acceleration detection element 4 in a plan view from the Z-axis direction. Here, the recess 311 formed in the cavity 31 is smaller than the inner periphery of the frame 32 in a plan view from the Z-axis direction. Therefore, the upper surface of the cavity 31 has an exposed portion 312 that is exposed inside the frame 32. The base 3 supports the acceleration detection element 4 from below at this exposed portion 312.

[0015] The base 3 also has a protruding portion 39 that protrudes from the cover 5 toward the negative side in the X-axis direction and has an upper surface exposed to the outside of the accommodation space S. The wiring group 7 is drawn out from inside the accommodation space S onto the protruding portion 39.

[0016] Although the base body 3 has been described above, the configuration of the base body 3 is not particularly limited as long as it can support the acceleration detecting element 4.

[0017] <Acceleration detection element 4> 2, the acceleration detecting element 4 is composed of a laminate of an insulating layer 2D and a first silicon layer 2A. The acceleration detecting element 4 is disposed inside the frame portion 32 of the base 3 without contacting the frame portion 32, and is supported by the exposed portion 312 of the base 3. As shown in FIG. 1, the acceleration detecting element 4 has a movable portion 41 that displaces in the X-axis direction relative to the base 3, a fixed portion 44 fixed to the exposed portion 312 of the base 3, and a pair of spring portions 42 and 43 that connect the movable portion 41 and the fixed portion 44.

[0018] The movable portion 41 has a base 410 extending in the X-axis direction, a first movable comb electrode 411 protruding from the base 410 toward the positive side in the Y-axis direction, and a second movable comb electrode 412 protruding from the base 410 toward the negative side in the Y-axis direction.

[0019] The fixed portion 44 is located on the positive side of the movable portion 41 in the Y-axis direction and has a first fixed comb-tooth electrode 441 that meshes with the first movable comb-tooth electrode 411, and a second fixed comb-tooth electrode 442 that is located on the negative side of the movable portion 41 in the Y-axis direction and meshes with the second movable comb-tooth electrode 412. The fixed portion 44 further has a first support portion 443 that is located on the positive side of the movable portion 41 in the X-axis direction and a second support portion 444 that is located on the negative side of the movable portion 41 in the X-axis direction. An insulating separator 8 is provided between the fixed portion 44 and the frame portion 32, thereby insulating the base 3 and the acceleration detection element 4. The insulating separator 8 is made of, for example, silicon oxide.

[0020] Both spring portions 42 and 43 are elastically deformable in the X-axis direction. Spring portion 42 is located between and connects base portion 410 and first support portion 443. On the other hand, spring portion 43 is located between and connects base portion 410 and second support portion 444.

[0021] When acceleration in the X-axis direction is applied to the acceleration detection element 4 configured as described above, the movable portion 41 is displaced in the X-axis direction relative to the base body 3 while elastically deforming the spring portions 42 and 43. In response to this displacement, the capacitance between the first movable comb electrode 411 and the first fixed comb electrode 441 and the capacitance between the second movable comb electrode 412 and the second fixed comb electrode 442 change in opposite phases. Therefore, acceleration can be detected based on these changes in capacitance.

[0022] Although the acceleration detecting element 4 has been described above, the configuration of the acceleration detecting element 4 is not particularly limited as long as it can detect acceleration.

[0023] ≪Wiring group 7≫ 1 and 2, the wiring group 7 is disposed on the upper surface of the SOI substrate 2, i.e., on the upper surface of the insulating layer 2D. The wiring group 7 is disposed on the upper surface of the protruding portion 39 and includes three terminals 711, 712, and 713 exposed to the outside of the accommodation space S, and three wires 721, 722, and 723 that pass between the base 3 and the lid 5 and are routed inside and outside the accommodation space S to electrically connect the terminals 711, 712, and 713 to the acceleration detecting element 4. The wire 721 electrically connects the terminal 711 and the movable portion 41, the wire 722 electrically connects the terminal 712 and the first fixed comb-tooth electrode 441, and the wire 723 electrically connects the terminal 713 and the second fixed comb-tooth electrode 442. These three wires 721, 722, and 723 are electrically connected to the movable section 41, the first fixed comb-teeth electrode 441, and the second fixed comb-teeth electrode 442, respectively, through vias that penetrate the insulating layer 2D.

[0024] <Lid 5> 2, the lid 5 is joined to the base 3 via a joining member 6, and a housing space S for housing the acceleration detecting element 4 is formed between the lid 5 and the base 3. The lid 5 is made of a silicon substrate. However, the lid 5 is not limited to this, and may be made of a glass substrate, a quartz substrate, or the like.

[0025] The lid 5 is located above the base 3 and has a recess 51 that opens to its bottom surface. The recess 51 overlaps with the acceleration detection element 4 in a plan view from the Z-axis direction, and functions as a relief that prevents contact between the lid 5 and the acceleration detection element 4. The lid 5 is bonded to the top surface of the base 3 via a bonding member 6 at its bottom surface, which has a rectangular frame shape that surrounds the recess 51. The bonding member 6 is, for example, glass paste. The lid 5 also has a through hole 53 that penetrates its top surface and the bottom surface of the recess 51. The through hole 53 is used to adjust the atmosphere in the housing space S during the manufacture of the physical quantity sensor 1, and is then sealed with a sealing material 57.

[0026] For ease of explanation, in the following, the surface of the lid body 5 that is joined to the joining member 6, i.e., the lower surface of the lid body 5, will also be referred to as the lid body joining surface 50, and the surface of the base body 3 that is joined to the joining member 6, i.e., the area on the upper surface of the base body 3 that faces the lid body joining surface 50, will also be referred to as the base joining surface 30.

[0027] The lid joint surface 50, the base joint surface 30, and the joint member 6 overlap each other in a plan view from the Z-axis direction, forming a rectangular frame shape. As described in the manufacturing method below, during the process of joining the lid 5 and the base 3, the lid 5 and the base 3 are pressed together, causing the joint member 6 located therebetween to be crushed and protrude into or out of the accommodation space S. If the joint member 6 protrudes excessively, various problems may occur, such as: (a) the joint member 6 comes into contact with the movable part 41, preventing the movable part 41 from moving; (b) the terminals 711, 712, and 713 are covered by the joint member 6, resulting in poor connection with an external device; and (c) the process of removing unnecessary portions of the lid 5 during the manufacture of the physical quantity sensor 1, as described in the manufacturing method below, may not proceed smoothly. These problems may result in reduced reliability and yield of the physical quantity sensor 1.

[0028] The protrusion of the bonding member 6 is particularly noticeable in the portions where it overlaps with the wirings 721, 722, and 723. This is because the bonding member 6 is crushed thinner than other portions by the thickness of the wirings 721, 722, and 723. Furthermore, since the bonding member 6 has a rectangular frame shape, the protrusion of the bonding member 6 is also noticeable at each corner. This is because the crushed bonding member 6 tends to concentrate at each corner.

[0029] Therefore, in the physical quantity sensor 1, as shown in FIGS. 1 and 2, pillar structures 9 are formed on the lid bonding surface 50 to suppress protrusion of the bonding member 6. As described above, protrusion of the bonding member 6 occurs significantly at the portions overlapping with the wirings 721, 722, and 723 and at each corner. Therefore, in this embodiment, as shown in FIG. 1, pillar structures 9 are partially formed in five locations on the lid bonding surface 50: the portions overlapping with the wirings 721, 722, and 723 and at each corner. By forming the pillar structures 9 only on a portion of the lid bonding surface 50 in this manner, protrusion of the bonding member 6 can be effectively suppressed while minimizing the reduction in mechanical strength of the lid 5 due to the formation of the pillar structures 9. However, the present invention is not limited to this. For example, as shown in FIG. 3, the pillar structures 9 may be formed in a frame shape around the entire periphery of the lid bonding surface 50. According to such a configuration, the mechanical strength of the lid body 5 may be lower than that of the present embodiment, but protrusion of the joining member 6 can be effectively suppressed over the entire periphery.

[0030] The pillar structures 9 will be described in detail below with reference to Figures 4 and 5. Note that the five pillar structures 9 have the same configuration, so for ease of explanation, Figure 4 shows only the portions overlapping with the wirings 721, 722, and 723, and Figure 5 shows only the portions overlapping with the wirings 721, 722, and 723 and one corner.

[0031] The pillar structure 9 of this embodiment is a micropillar structure. As shown in FIGS. 4 and 5 , the pillar structure 9 includes a bottomed recess 91 that opens to the lid joint surface 50 and multiple pillars 92 that are erected on the bottom surface of the recess 91 and spaced apart from one another. Each pillar 92 extends along the Z-axis. This configuration allows a portion of the joining member 6 that is crushed between the lid joint surface 50 and the base joint surface 30 to enter the recess 91, thereby preventing the joining member 6 from protruding. This reduces the occurrence of the aforementioned problems (a), (b), and (c). Furthermore, the joining member 6 that has entered the recess 91 comes into contact with the multiple pillars 92 arranged within the recess 91, thereby increasing the contact area between the joining member 6 and the lid 5. Furthermore, the multiple pillars 92 function as anchors, thereby more firmly joining the joining member 6 and the lid 5. Furthermore, protrusion of the joining member 6 can be prevented without increasing the size of the physical quantity sensor 1.

[0032] Such pillar structures 9 can be formed, for example, by metal-assisted etching (noble metal catalytic etching). Metal-assisted etching is anisotropic etching that uses a noble metal as a catalyst. Only the silicon interface in contact with the noble metal, such as silver nanoparticles, is selectively etched, making it possible to process with a high aspect ratio. Therefore, by using metal-assisted etching, the pillar structures 9 can be formed easily and accurately. However, the method for forming the pillar structures 9 is not particularly limited, and for example, silicon deep trench dry etching using the Bosch process, wet etching, etc. may be used.

[0033] 6, the plurality of pillars 92 are regularly arranged in a matrix along the X-axis direction and the Y-axis direction. By regularly arranging the plurality of pillars 92 in this manner, there is no variation in the density of the pillars 92 within the recess 91, and therefore the aforementioned effects of suppressing protrusion of the joining member 6 and increasing the joining strength between the joining member 6 and the lid 5 can be achieved evenly throughout the recess 91. Note that, for example, the same effects as those of this embodiment can be achieved by regularly arranging the plurality of pillars 92 in a checkerboard pattern as shown in FIG. 7. However, the arrangement of the plurality of pillars 92 is not particularly limited, and they may be arranged irregularly, for example.

[0034] As shown in FIG. 6 , each pillar 92 is a square prism. That is, it is a pillar with a square cross section. With this configuration, the surface area of ​​the pillar 92 can be made larger than, for example, a cylindrical, triangular prism, or pentagonal prism having the same width W. This allows for a larger contact area between the joining member 6 and the lid 5, thereby more firmly joining the joining member 6 and the lid 5. Note that the term "square prism" does not only refer to a shape whose cross section is identical to a square, but also includes a shape whose cross section can be considered substantially the same as a square, taking into account, for example, shape deviations and rounded corners that may occur during manufacturing. However, the shape of each pillar 92 is not particularly limited and may be a cylindrical, triangular prism, pentagonal prism, or the like. Furthermore, at least one pillar 92 may have a different shape from the other pillars 92, for example, a mixture of square pillars 92 and cylindrical pillars 92.

[0035] 4 and 5, the top surface of each pillar portion 92, i.e., the surface facing the base 3, is flush with the lid joint surface 50. In other words, the depth L of the recess 91 and the height of the pillar portion 92 are equal. This configuration facilitates contact between each pillar portion 92 and the joint member 6, thereby increasing the contact area between the joint member 6 and the lid 5. This further increases the joint strength between the joint member 6 and the lid 5. However, this is not limiting, and the top surface of each pillar portion 92 may protrude below the lid joint surface 50 or may be recessed above the lid joint surface 50.

[0036] As shown in FIG. 4, the depth L of the recess 91 is preferably 1 μm or more and 100 μm or less. By setting the depth L to such a value, the space within the recess 91 is sufficiently large, allowing a sufficient amount of the bonding member 6 to enter the recess 91. Therefore, the protrusion of the bonding member 6 can be effectively suppressed. Furthermore, the recess 91 can be prevented from becoming deeper than necessary, thereby preventing the physical quantity sensor 1 from becoming larger. Furthermore, it is possible to prevent a decrease in the manufacturing efficiency of the physical quantity sensor 1, which would otherwise be caused by a longer time required to form the pillar structure 9. The depth L of the recess 91 is more preferably 5 μm or more and 50 μm or less, and even more preferably 10 μm or more and 30 μm or less. By setting the depth L to such a value, the above-described effects become more pronounced. However, the depth L of the recess 91 is not particularly limited.

[0037] As shown in FIG. 6 , the width W of each pillar portion 92 is preferably 0.1 μm or more and 10 μm or less. By setting the width W to such a value, the pillar portions 92 can be made sufficiently thin, allowing more pillar portions 92 to be placed within the recess 91. This increases the contact area between the joining member 6 and the lid 5, and allows more anchors to be formed. This results in a stronger bond between the joining member 6 and the lid 5. The width W of each pillar portion 92 is more preferably 0.1 μm or more and 5 μm or less, and even more preferably 0.1 μm or more and 1 μm or less. By setting the width W to such a value, the aforementioned effects become more pronounced. However, the width W of each pillar portion 92 is not particularly limited. Furthermore, pillar portions 92 with different widths W may be mixed.

[0038] As shown in FIG. 6 , the separation distance D between a pair of adjacent column portions 92 is preferably 0.1 μm or more and 10 μm or less. By setting the separation distance D to 0.1 μm or more, the gap between the pair of adjacent column portions 92 is sufficiently large, making it easier for the joining member 6 to enter the gap. This effectively prevents the joining member 6 from overflowing. By setting the separation distance D to 10 μm or less, the gap between the pair of adjacent column portions 92 is not excessively large, allowing an appropriate number of column portions 92 to be formed in the recess 91. This ensures a sufficiently large contact area between the joining member 6 and the lid 5, and allows a sufficient number of anchors to be formed. This allows the joining member 6 and the lid 5 to be firmly joined. The separation distance D is more preferably 0.1 μm or more and 5 μm or less, and even more preferably 0.1 μm or more and 1 μm or less. By setting the separation distance D to such a value, the aforementioned effects become more pronounced. However, the separation distance D is not particularly limited.

[0039] Furthermore, the occupancy rate of the pillar portions 92 in the recess 91 (total volume of each pillar portion 92 / volume of the recess 91) is preferably 10% or more and 50% or less. By setting this occupancy rate, the pillar portions 92 can be arranged in the recess 91 with an appropriate density. This makes it easier for the joining member 6 to enter the recess 91, more effectively preventing the joining member 6 from protruding, and ensures a sufficiently large contact area between the joining member 6 and the lid 5, thereby firmly joining the joining member 6 and the lid 5. The occupancy rate is more preferably 20% or more and 40% or less, and even more preferably 25% or more and 35% or less. By setting this occupancy rate, the above-mentioned effects become more pronounced. However, the occupancy rate is not particularly limited.

[0040] The configuration of the pillar structure 9 has been described above in detail. Here, as shown in FIG. 1 , each pillar structure 9 arranged overlapping each corner of the joining member 6 is bent at a right angle along the corner and has a portion extending in the X-axis direction and a portion extending in the Y-axis direction. This configuration ensures that the pillar structure 9 is sufficiently large, effectively preventing the joining member 6 from protruding from each corner. Furthermore, as shown in FIGS. 1 and 5 , the pillar structure 9 arranged overlapping the wirings 721, 722, and 723 is formed to protrude from the wirings 721, 722, and 723 in a direction perpendicular to the X-axis direction, which is the extension direction of the wirings 721, 722, and 723, in a plan view from the Z-axis direction, that is, on both sides of the Y-axis direction. This configuration effectively prevents the joining member 6 from protruding from the portions overlapping with the wirings 721, 722, and 723.

[0041] The above has described the configuration of the physical quantity sensor 1. Next, a description will be given of a manufacturing method for the physical quantity sensor 1. As shown in Fig. 8, the manufacturing method for the physical quantity sensor 1 includes a pillar structure forming step S1 of forming the pillar structure 9 on the lid body 5, an acceleration detecting element forming step S2 of forming the acceleration detecting element 4, a joining member arranging step S3 of arranging a joining member 6 on the lid body joining surface 50, and a joining step S4 of joining the base body 3 and the lid body 5 via the joining member 6.

[0042] <Pillar structure forming step S1> In the pillar structure forming step S1, first, as shown in FIG. 9, a silicon substrate 500 that serves as a base material for the lid body 5 is prepared. Note that a plurality of lid bodies 5 are integrally formed on the silicon substrate 500. Next, as shown in FIG. 10, recesses are formed in the lower surface of the silicon substrate 500 by, for example, dry etching. In addition to recesses 51 and through-holes 53, the recesses include recesses 59 for preventing contact between the silicon substrate 500 and terminals 711, 712, and 713. Next, as shown in FIG. 11, pillar structures 9 are formed in predetermined locations on the lower surface of the silicon substrate 500 by, for example, metal-assisted etching.

[0043] <Acceleration detection element forming process S2> In the acceleration detecting element forming process S2, first, as shown in FIG. 12, an SOI substrate 2 is prepared as a base material for the base 3 and the acceleration detecting elements 4. Recesses 311 are formed in advance in the SOI substrate 2. Next, as shown in FIG. 13, the acceleration detecting elements 4 and frame 32 are formed in the first silicon layer 2A by, for example, dry etching. Next, an insulating separation section 8 for insulating the acceleration detecting elements 4 from the frame 32 is formed by sputtering or the like, and further, an insulating layer 2D is formed on the first silicon layer 2A. In this way, the base 3 and the acceleration detecting elements 4 are formed collectively from the SOI substrate 2. Next, as shown in FIG. 14, a wiring group 7 is formed on the insulating layer 2D.

[0044] <Joint member placement process S3> In the bonding member placement step S3, as shown in Fig. 15, a glass paste, which is the bonding member 6, is applied to the lid bonding surface 50 of the lid 5 by, for example, screen printing. The glass paste is a glass frit dispersed in an organic binder. The glass paste may be applied to the base bonding surface 30, or may be applied to both the lid bonding surface 50 and the base bonding surface 30.

[0045] ≪Joining process S4≫ In the bonding process S4, as shown in FIG. 16, the lid body 5 and the base body 3 are first pressed against each other and heat-treated to bond them together. This forms a housing space S for housing the acceleration detection element 4. During this process, a portion of the bonding member 6, crushed between the lid body 5 and the base body 3, penetrates into the pillar structure 9, effectively preventing the bonding member 6 from protruding into or out of the housing space S. Next, the atmosphere in the housing space S is adjusted via the through-hole 53, and the housing space S is sealed with a sealant 57 as shown in FIG. 17. Next, as shown in FIG. 18, the lid body 5 is half-diced to remove unnecessary portions. This exposes the terminals 711, 712, and 713 to the outside. If the bonding member 6 protrudes out of the housing space S along the underside of the lid body 5, the dicing saw may come into contact with the bonding member 6 during half-dicing, potentially preventing successful removal of the unnecessary portions. Finally, as shown in FIG. 19, the physical quantity sensors 1 are separated into individual pieces by dicing. In this way, the physical quantity sensor 1 is manufactured.

[0046] According to the manufacturing method described above, a part of the joining member 6 that is crushed between the lid body 5 and the base body 3 can penetrate into the pillar structure 9, thereby suppressing the protrusion of the joining member 6. Therefore, the protrusion of the joining member 6 can be suppressed. Furthermore, the joining member 6 that has penetrated into the recess 91 comes into contact with the multiple pillars 92 erected in the recess 91, thereby increasing the contact area between the joining member 6 and the lid body 5 and also causing the multiple pillars 92 to function as anchors, thereby enabling the joining member 6 and the lid body 5 to be joined more firmly.

[0047] The physical quantity sensor 1 has been described above. As described above, the physical quantity sensor 1 includes a base 3, an acceleration detection element 4 that is supported by the base 3 and serves as a physical quantity detection element for detecting a physical quantity, and a lid 5 that is joined to the base 3 via a joining member 6 and houses the acceleration detection element 4 between the base 3 and the lid 5. When the surface of the base 3 that is joined to the joining member 6 is defined as a base joining surface 30 and the surface of the lid 5 that is joined to the joining member 6 is defined as a lid joining surface 50, a pillar structure 9 is formed on at least one of the base joining surface 30 and the lid joining surface 50. The pillar structure 9 includes a bottomed recess 91 and a plurality of pillars 92 that are erected on the bottom surface of the recess 91 and spaced apart from one another. In particular, in this embodiment, the pillar structure 9 is formed on the lid joining surface 50. The joining member 6 extends into the recess 91. According to this configuration, a part of the joining member 6 that is crushed between the lid body 5 and the base body 3 can enter the pillar structure 9, thereby suppressing the protrusion of the joining member 6. Therefore, the protrusion of the joining member 6 can be suppressed. Furthermore, the joining member 6 that has entered the recess 91 comes into contact with the multiple pillar portions 92 erected in the recess 91, thereby increasing the contact area between the joining member 6 and the lid body 5 and also causing the multiple pillar portions 92 to function as anchors, thereby enabling the joining member 6 and the lid body 5 to be joined more firmly.

[0048] As described above, the joining member 6 has a rectangular frame shape in a plan view of the base 3, and the pillar structures 9 overlap the corners of the joining member 6. The corners are areas where the joining member 6 is particularly likely to protrude. Therefore, with this configuration, the joining member 6 can be more effectively prevented from protruding.

[0049] As described above, the physical quantity sensor 1 has wirings 721, 722, and 723 that are electrically connected to the acceleration detection element 4 inside the lid 5, pass between the base 3 and the lid 5, and are drawn out to the outside of the lid 5. In a plan view of the base 3, the pillar structure 9 overlaps with the wirings 721, 722, and 723. The overlapping portions with the wirings 721, 722, and 723 are locations where the joining member 6 is particularly likely to protrude. Therefore, with this configuration, the joining member 6 can be more effectively prevented from protruding.

[0050] Furthermore, as described above, in a plan view of the base 3, the pillar structures 9 are formed so as to protrude from both sides of the wirings 721, 722, and 723 in a direction perpendicular to the extending direction of the wirings 721, 722, and 723. With this configuration, the protrusion of the bonding member 6 can be more effectively suppressed.

[0051] As described above, the top surface of each pillar 92 is flush with the surface on which the recess 91 is formed, which in this embodiment is the lid joint surface 50. This configuration facilitates contact between each pillar 92 and the joint member 6, thereby increasing the contact area between the joint member 6 and the lid 5. This further increases the joint strength between the joint member 6 and the lid 5.

[0052] As described above, the plurality of pillars 92 are regularly arranged in a matrix or checkerboard pattern. With this configuration, the pillars 92 are uniformly arranged within the recess 91, so that the effects of suppressing protrusion of the joining member 6 and increasing the joining strength between the joining member 6 and the lid 5 can be achieved evenly throughout the entire recess 91.

[0053] As described above, the width W of each pillar portion 92 is 0.1 μm or more and 10 μm or less. With this configuration, the pillar portions 92 can be made sufficiently thin, and accordingly, more pillar portions 92 can be arranged in the recess 91. This increases the contact area between the joining member 6 and the lid 5, and allows more anchors to be formed. This allows the joining member 6 and the lid 5 to be joined more firmly.

[0054] As described above, the separation distance D between a pair of adjacent column portions 92 is 0.1 μm or more and 10 μm or less. With this configuration, the gap between the pair of adjacent column portions 92 is sufficiently large, making it easier for the joining member 6 to enter the gap. This effectively prevents the joining member 6 from protruding. Furthermore, the gap between the pair of adjacent column portions 92 does not become excessively large, allowing an appropriate number of column portions 92 to be formed in the recess 91. This ensures a sufficiently large contact area between the joining member 6 and the lid 5, while also allowing a sufficient number of anchors to be formed. This allows the joining member 6 and the lid 5 to be firmly joined.

[0055] As described above, the occupancy rate of the pillars 92 in the recesses 91 is 10% or more and 50% or less. With this configuration, the pillars 92 can be arranged at an appropriate density in the recesses 91. This makes it easier for the joining members 6 to enter the recesses 91, more effectively preventing the joining members 6 from protruding, and also ensures a sufficiently large contact area between the joining members 6 and the lid 5, thereby firmly joining the joining members 6 and the lid 5.

[0056] As described above, the depth L of the recess 91 is not less than 1 μm and not more than 100 μm. With this configuration, the space inside the recess 91 is sufficiently large, and a sufficient amount of the bonding member 6 can enter the recess 91. Therefore, it is possible to effectively prevent the bonding member 6 from protruding. It is also possible to prevent the recess 91 from becoming deeper than necessary, and to prevent the physical quantity sensor 1 from becoming larger. It is also possible to prevent a decrease in the manufacturing efficiency of the physical quantity sensor 1, which would be caused by a longer time required to form the pillar structure 9.

[0057] As described above, the manufacturing method of the physical quantity sensor 1 is a manufacturing method of the physical quantity sensor 1 having the base 3 supporting the acceleration detection element 4, which is a physical quantity detection element that detects a physical quantity, and the lid body 5 that houses the acceleration detection element 4 between the base 3 and the lid body 5 by being joined to the base 3, and includes the following steps: a pillar structure forming step S1 of forming a pillar structure 9 on at least one of the base joining surface 30 and the lid body joining surface 50, the pillar structure 9 having a bottomed recess 91 and a plurality of pillar portions 92 standing on the bottom surface of the recess 91 and arranged at intervals from each other, when the surface of the base 3 that is joined to the lid body 5 is defined as the base joining surface 30 and the surface of the lid body 5 that is joined to the base 3 is defined as the lid body joining surface 50; a joining member arranging step S3 of arranging a joining member 6 on at least one of the base joining surface 30 and the lid body joining surface 50; and a joining step S4 of joining the base 3 and the lid body 5 via the joining member 6. According to this manufacturing method, a part of the joining member 6 that is crushed between the lid body 5 and the base body 3 can penetrate into the pillar structure 9, thereby suppressing the protrusion of the joining member 6. Therefore, the protrusion of the joining member 6 can be suppressed. Furthermore, the joining member 6 that has penetrated into the recess 91 comes into contact with the multiple pillar portions 92 erected in the recess 91, thereby increasing the contact area between the joining member 6 and the lid body 5 and also causing the multiple pillar portions 92 to function as anchors, thereby enabling the joining member 6 and the lid body 5 to be joined more firmly.

[0058] Second Embodiment Fig. 20 is an enlarged cross-sectional view showing a joint between the cover and the base of the physical quantity sensor according to the second embodiment, and Fig. 21 is an enlarged cross-sectional view showing a state after the joining member arrangement step has been completed.

[0059] The physical quantity sensor 1 of this embodiment is similar to the first embodiment described above, except for the configuration of the joining member 6. In the following description, the differences between this embodiment and the first embodiment will be mainly described, and a description of similar points will be omitted. In addition, in each drawing of this embodiment, the same reference numerals are used to designate the same components as those in the above-described embodiment.

[0060] As shown in FIG. 20 , in the physical quantity sensor 1 of this embodiment, the bonding member 6 is formed by eutectic bonding between a first metal film 61 formed on the lid bonding surface 50 and a second metal film 62 formed on the base bonding surface 30. Because the bonding member 6 is conductive, an insulating layer 73 is interposed between the second metal film 62 and the wirings 721, 722, and 723 in this embodiment. In this embodiment, the first metal film 61 is made of germanium (Ge), and the second metal film 62 is made of aluminum (Al). The insulating layer 73 is made of silicon oxide. However, the materials of the first and second metal films 61 and 62 and the insulating layer 73 are not particularly limited. The first and second metal films 61 and 62 and the insulating layer 73 are each formed by, for example, sputtering.

[0061] In the bonding member placement process S3, as shown in FIG. 21, a process of depositing a first metal film 61 on the lid body bonding surface 50 and a process of depositing a second metal film 62 on the base bonding surface 30 are performed. However, since the pillar structures 9 formed on the lid body bonding surface 50 have a fine structure, the first metal film 61 can be deposited on the pillar structures 9 without any problems.

[0062] The second embodiment can also achieve the same effects as the first embodiment described above.

[0063] Although the physical quantity sensor and the method for manufacturing the physical quantity sensor of the present invention have been described above based on the illustrated embodiments, the present invention is not limited to these, and the configuration of each part can be replaced with any configuration or process having a similar function. Furthermore, any other configuration or process may be added to the present invention.

[0064] For example, in the above-described embodiment, the physical quantity detection element is the acceleration detection element 4 that detects acceleration in the X-axis direction, but this is not limited thereto and may be an acceleration detection element that detects acceleration in the Y-axis direction or an acceleration detection element that detects acceleration in the Z-axis direction. Furthermore, the physical quantity detection element may be an angular velocity detection element that detects angular velocity around the X-axis, an angular velocity detection element that detects angular velocity around the Y-axis, or an angular velocity detection element that detects angular velocity around the Z-axis. Furthermore, the physical quantity sensor 1 may be configured to have a plurality of physical quantity detection elements that detect different targets within the accommodation space S.

[0065] 22, the pillar structures 9 may be formed on the base bonding surface 30 instead of the lid bonding surface 50. With such a configuration, the same effects as those of the above-described embodiment can be achieved. As shown in FIG. 23, the pillar structures 9 may be formed on both the base bonding surface 30 and the lid bonding surface 50. As shown in FIGS. 24 and 25, the pillars 92 may be formed to extend in a wall shape. [Explanation of symbols]

[0066] 1...physical quantity sensor, 2...SOI substrate, 2A...first silicon layer, 2B...silicon oxide layer, 2C...second silicon layer, 2D...insulating layer, 3...base, 30...base bonding surface, 31...cavity portion, 311...recess, 312...exposed portion, 32...frame portion, 39...protruding portion, 4...acceleration detection element, 41...movable portion, 410...base portion, 411...first movable comb electrode, 412...second movable comb electrode, 42...spring portion, 43...spring portion, 44...fixed portion, 441...first fixed comb electrode, 442...second fixed comb electrode, 443...first support portion, 444...second support portion, 5...lid, 50...lid bonding surface, 500...silicon substrate, 51...recess, 53...through hole, 57...sealing material, 59...recess, 6...bonding member, 61...first metal film, 62...second metal film, 7...wiring group, 711...terminal, 712...terminal, 713...terminal, 721...wiring, 722...wiring, 723...wiring, 73...insulating layer, 8...insulating separation portion, 9...pillar structure, 91...recess, 92...pillar portion, D...separation distance, L...depth, S...accommodation space, S1...pillar structure forming step, S2...acceleration detection element forming step, S3...bonding member arranging step, S4...bonding step

Claims

1. a substrate; a physical quantity detection element supported on the base and detecting a physical quantity; a lid body that is joined to the base body via a joining member and that houses the physical quantity detection element between the lid body and the base body, a surface of the base that is joined to the joining member is defined as a base joining surface; When the surface of the lid body joined to the joining member is defined as a lid body joining surface, a pillar structure is formed on at least one of the base bonding surface and the lid bonding surface, the pillar structure having a bottomed recess and a plurality of pillar portions erected on the bottom surface of the recess and arranged at intervals from each other, and the bonding member extends into the recess.

2. In a plan view of the base, The joining member has a rectangular frame shape, The physical quantity sensor according to claim 1 , wherein the pillar structure overlaps a corner of the joining member.

3. a wiring electrically connected to the physical quantity detection element inside the lid, passing between the base and the lid and extending to the outside of the lid; In a plan view of the base, The physical quantity sensor according to claim 1 , wherein the pillar structure overlaps with the wiring.

4. In a plan view of the base, The physical quantity sensor according to claim 3 , wherein the pillar structure is formed so as to protrude from both sides of the wiring in a direction perpendicular to the extending direction of the wiring.

5. The physical quantity sensor according to claim 1 , wherein a top surface of each of the pillars is flush with a surface on which the recess is formed.

6. The physical quantity sensor according to claim 1 , wherein the plurality of pillars are regularly arranged in a matrix or checkerboard pattern.

7. The physical quantity sensor according to claim 1 , wherein the width of each of the pillars is not less than 0.1 μm and not more than 10 μm.

8. The physical quantity sensor according to claim 1 , wherein the distance between the adjacent pair of pillars is 0.1 μm or more and 10 μm or less.

9. The physical quantity sensor according to claim 1 , wherein the occupancy rate of the pillars relative to the recesses is 10% or more and 50% or less.

10. The physical quantity sensor according to claim 1 , wherein the depth of the recess is not less than 1 μm and not more than 100 μm.

11. a wiring electrically connected to the physical quantity detection element inside the lid, passing between the base and the lid and extending to the outside of the lid; When viewed from above, the joining member has a rectangular frame shape, the pillar structure overlaps a corner of the joining member and the wiring, and is formed to protrude on both sides in a direction perpendicular to an extending direction of the wiring, The plurality of pillars are regularly arranged in a matrix or checkerboard pattern, a top surface of each of the pillars is flush with a surface on which the recess is formed; The width of each of the pillars is 0.1 μm or more and 10 μm or less, The distance between the adjacent pair of column portions is 0.1 μm or more and 10 μm or less, an occupancy rate of the column portion relative to the recess portion is 10% or more and 50% or less; The physical quantity sensor according to claim 1 , wherein the depth of the recess is not less than 1 μm and not more than 100 μm.

12. A method for manufacturing a physical quantity sensor having a base supporting a physical quantity detection element that detects a physical quantity, and a lid that is joined to the base to house the physical quantity detection element between the base and the lid, comprising: a pillar structure forming step of forming a pillar structure on at least one of the base joining surface and the lid joining surface, the pillar structure having a bottomed recess and a plurality of pillar portions erected on the bottom surface of the recess and arranged at intervals from each other, when a surface of the base that is joined to the lid is defined as a base joining surface and a surface of the lid that is joined to the base is defined as a lid joining surface; a bonding member placement step of placing a bonding member on at least one of the base bonding surface and the lid bonding surface; a bonding step of bonding the base body and the lid body via the bonding member.

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