JP4844118B2 - Sensor module and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sensor module including a sensor element, an IC chip on which a signal processing circuit for processing an output signal of the sensor element is formed, and a package in which the sensor element is housed, and a method for manufacturing the sensor module.

  Conventionally, a sensor element (for example, an MEMS such as an acceleration sensor and a gyro sensor) formed by utilizing micromachining technology, and an IC chip on which a signal processing circuit for processing an output signal of the sensor element is formed Has been proposed (see, for example, Patent Document 1).

  Here, for example, as shown in FIG. 19, the sensor module disclosed in Patent Document 1 includes a sensor element A ′ composed of a gyro sensor (angular velocity sensor), an IC chip 4 ′, a sensor element A ′, and an IC chip. 4 ′, each of which includes a mounting substrate 50 ′ composed of an MID substrate on which flip chip mounting is performed, and a storage recess (hereinafter referred to as “sensor recess”) for storing the sensor element A ′ on one surface (the lower surface in FIG. 19) of the mounting substrate 50 ′. A first storage recess 51 ′ is formed, and a storage recess (hereinafter referred to as a second storage recess) for storing the IC chip 4 ′ on the other surface (the upper surface in FIG. 19) of the mounting substrate 50 ′. 52 ′) is formed. That is, in the sensor module having the configuration shown in FIG. 19, the sensor element A ′ is flip-chip mounted on the inner bottom surface of the first housing recess 51 ′ in the mounting substrate 50 ′, and the second housing recess in the mounting substrate 50 ′. An IC chip 4 ′ is flip-chip mounted on the inner bottom surface of the location 52 ′. The sensor module described above is filled in the first housing recess 51 ′ and the first sealing portion 61 ′ filled with the sensor element A ′ and the second housing recess 52 ′. And a second sealing portion 62 ′ that seals the IC chip 4 ′.

  By the way, an acceleration sensor, a gyro sensor, and the like are widely known as MEMS, and as an acceleration sensor, a piezoelectric element that detects acceleration by a change in resistance value due to a strain of a gauge resistance composed of a piezoresistor when acceleration is applied. A resistance-type acceleration sensor, a capacitance-type acceleration sensor that detects acceleration based on a change in capacitance between a fixed electrode and a movable electrode when acceleration is applied, and the like are known.

  As a piezoresistive acceleration sensor, a cantilever type is supported in such a manner that a weight portion arranged inside a rectangular frame-like frame portion is swingably supported by the frame portion via a bending portion extended in one direction. Also proposed is a dual-support type that is swingably supported by the frame portion through a pair of flexure portions that are extended in two opposite directions with weight portions arranged inside the frame-shaped frame portion. In recent years, a weight portion arranged inside a frame-like frame portion is supported by the frame portion through four flexible portions extended in four directions so as to be swingable, and accelerations in three directions orthogonal to each other. Have been proposed (see, for example, Patent Documents 2 and 3).

In the above-described piezoresistive acceleration sensor, the weight part and the bending part constitute a movable part, and the piezoresistor constitutes a sensing part. Further, in a capacitive acceleration sensor (for example, see Patent Document 4) and a gyro sensor (for example, see Patent Document 5), a weight part provided with a movable electrode or a weight part that also serves as a movable electrode constitutes the movable part. The sensing unit is configured by the fixed electrode and the movable electrode.
JP 2005-129888 A JP 2004-109114 A JP 2004-233072 A JP 2004-028912 A JP 2005-292117 A

  By the way, in the sensor module having the configuration shown in FIG. 19, since the sensor element A ′ and the IC chip 4 ′ are arranged so as to overlap each other in the thickness direction, both are mounted on the same plane of the mounting substrate. As compared with the above, there is an advantage that the planar size of the mounting board 50 ′ which also serves as a package can be reduced, and the mounting area on a circuit board such as a printed board can be reduced.

  However, in the sensor module having the configuration shown in FIG. 19, since the planar size of the IC chip 4 ′ is limited by the opening area of the second housing recess 52 ′, the planar surface of the IC chip 4 ′ as shown in FIG. When the size is larger than the planar size of the sensor element A ′, it is necessary to make the area of the inner bottom surface of the second storage recess 52 ′ larger than the area of the inner bottom surface of the first storage recess 51 ′. Therefore, the mounting area on the circuit board is relatively large compared to the planar size of the sensor element A ′.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a sensor module and a method for manufacturing the same that can reduce the mounting area on a circuit board.

  According to the first aspect of the present invention, a sensor element, an IC chip on which a signal processing circuit for processing an output signal of the sensor element is formed, and a wiring for connecting the sensor element and the IC chip to an external circuit are formed. The package is composed of a cylindrical substrate in which the sensor element is disposed inside, and a plate-shaped substrate disposed on one end side in the axial direction of the cylindrical substrate. The sensor element is flip-chip mounted on one surface side, the IC chip is flip-chip mounted on the other surface side, and an external circuit connection terminal electrically connected to the wiring is the other end in the axial direction of the cylindrical substrate It is formed on the side.

  According to this invention, the package is configured by the cylindrical substrate on which the sensor element is disposed on the inner side and the plate-shaped substrate disposed on one end side in the axial direction of the cylindrical substrate, and on the one surface side of the plate-shaped substrate. The sensor element is flip-chip mounted, the IC chip is flip-chip mounted on the other side, and an external circuit connection terminal electrically connected to the wiring is formed on the other axial end of the cylindrical substrate Therefore, the mounting area on the circuit board can be further reduced without reducing the planar size of the IC chip.

  The invention of claim 2 is a method for manufacturing a sensor module according to claim 1, wherein an IC mounting step of flip-chip mounting an IC chip on the other surface side of the plate-like substrate, and a plate shape after the IC mounting step A substrate-to-substrate coupling step for mechanically and electrically coupling the substrate and the cylindrical substrate, and a sensor mounting step for flip-chip mounting the sensor element on the one surface side of the plate-shaped substrate after the substrate-to-substrate coupling step. It is characterized by.

  According to the present invention, a sensor module having a smaller mounting area on a circuit board can be provided.

  The invention of claim 3 is the bump forming step of forming bumps for mounting sensor elements on the one surface side of the plate-like substrate between the IC mounting step and the inter-substrate coupling step in the invention of claim 2. In the sensor mounting step, the sensor element is flip-chip mounted on the plate-like substrate via the bumps formed in the bump forming step.

  According to this invention, when the bump for mounting the sensor element is formed on the one surface side of the plate-like substrate by the stud bump method, the bump is formed as compared with the case where the bump is formed after the inter-substrate coupling step. Becomes easier.

  In the invention of claim 1, there is an effect that the mounting area on the circuit board can be further reduced.

  In the invention of claim 2, there is an effect that it is possible to provide a sensor module having a smaller mounting area on the circuit board.

(Embodiment 1)
The sensor module of this embodiment will be described with reference to FIGS.

  The sensor module of the present embodiment is an acceleration sensor module, and as shown in FIGS. 1 to 3, a sensor element A composed of an acceleration sensor element and a signal processing circuit for processing an output signal of the sensor element A are formed. The IC chip 4, the sensor element A and a wiring (not shown) for connecting the IC chip 4 to an external circuit are formed, and the sensor element A is housed in a box shape (in this embodiment, a rectangular box shape). Package 5. In the acceleration sensor module of this embodiment, the sensor element A and the IC chip 4 are flip-chip mounted on the package 5, and an underfill 8 in which the IC chip 4 is sealed is provided between the IC chip 4 and the package 5. Is formed. Here, in the acceleration sensor module of the present embodiment, the IC chip 4 is larger in plane size than the sensor element A, and the sensor element A arranged inside the package 5 is arranged outside the package 5. The package 5 is flip-chip mounted so as to be within the projection plane of the chip 4.

  Hereinafter, the sensor element A will be described in detail, and then the acceleration sensor module will be described in detail.

  As shown in FIG. 7, the sensor element A is formed using a first semiconductor substrate and has a sensor unit 1 having a sensing unit, which will be described later, and a sensing unit of the sensor substrate 1 formed using a second semiconductor substrate. A through-hole wiring forming substrate 2 having a plurality of through-hole wirings 24 electrically connected and sealed on one surface side (the upper surface side in FIG. 7B) of the sensor substrate 1, and a third semiconductor substrate And a cover substrate 3 formed on the other surface side of the sensor substrate 1 (on the lower surface side in FIG. 7B). Here, the outer peripheral shapes of the sensor substrate 1, the through-hole wiring formation substrate 2, and the cover substrate 3 are rectangular, and the through-hole wiring formation substrate 2 and the cover substrate 3 are formed to have the same outer dimensions as the sensor substrate 1. 8A is an enlarged view of a main part of FIG. 7B, and FIG. 8B is a schematic cross-sectional view taken along the line C-C ′ of FIG.

  The sensor substrate 1 described above processes an SOI wafer having an n-type silicon layer (active layer) 10c on an insulating layer (buried oxide film) 10b made of a silicon oxide film on a support substrate 10a made of a silicon substrate. The through-hole wiring forming substrate 2 is formed by processing the first silicon wafer, and the cover substrate 3 is formed by processing the second silicon wafer. That is, in this embodiment, the SOI wafer constitutes the first semiconductor substrate, the first silicon wafer constitutes the second semiconductor substrate, and the second silicon wafer constitutes the third semiconductor substrate. . In this embodiment, the thickness of the support substrate 10a in the SOI wafer is about 300 μm to 500 μm, the thickness of the insulating layer 10b is about 0.3 μm to 1.5 μm, and the thickness of the silicon layer 10c is about 4 μm to 10 μm. The thickness of the first silicon wafer is about 200 μm to 300 μm, and the thickness of the second silicon wafer is about 100 to 300 μm. However, these numerical values are not particularly limited. The surface of the silicon layer 10c, which is the main surface of the SOI wafer, is a (100) plane.

  As shown in FIGS. 9 to 11, the sensor substrate 1 includes a frame portion 11 having a frame shape (in this embodiment, a rectangular frame shape), and a weight portion 12 arranged inside the frame portion 11 is on one surface side. In FIG. 7 (b) and FIG. 9 (b), the frame portion 11 is swingably supported via four flexible strip-like bent portions 13 having flexibility. In other words, the sensor substrate 1 is swingably supported by the frame portion 11 via the four flexure portions 13 in which the weight portion 12 disposed inside the frame-shaped frame portion 11 extends from the weight portion 12 in four directions. Has been. Here, the frame portion 11 is formed using the above-described SOI wafer support substrate 10a, insulating layer 10b, and silicon layer 10c. On the other hand, the bending part 13 is formed using the silicon layer 10c in the above-described SOI wafer, and is sufficiently thinner than the frame part 11.

  The weight part 12 is continuously integrated with each of the rectangular parallelepiped core part 12a supported by the frame part 11 via the four flexure parts 13 and the four corners of the core part 12a when viewed from the one surface side of the sensor substrate 1. And four accompanying portions 12b having a rectangular parallelepiped shape connected to each other. In other words, the weight portion 12 is formed integrally with the core portion 12a and the core portion 12a in which the other end portion of each bending portion 13 whose one end portion is connected to the inner side surface of the frame portion 11 is connected to the outer surface. It has four accompanying parts 12b arranged in the space between the part 12a and the frame part 11. That is, each appendage portion 12b is disposed in a space surrounded by the frame portion 11 and the core portion 12a and the two bent portions 13 and 13 extending in a direction orthogonal to each other when viewed from the one surface side of the sensor substrate 1. In addition, a slit 14 is formed between each of the accompanying portions 12b and the frame portion 11, and the interval between the adjacent accompanying portions 12b with the bending portion 13 interposed therebetween is longer than the width dimension of the bending portion 13. Yes. Here, the core portion 12a is formed using the above-described SOI wafer support substrate 10a, the insulating layer 10b, and the silicon layer 10c, and each accompanying portion 12b is formed using the SOI wafer support substrate 10a. It is. Thus, the surface of each associated portion 12b on the one surface side of the sensor substrate 1 is from the plane including the surface of the core portion 12a to the other surface side of the sensor substrate 1 (FIGS. 7B and 9B). (Lower surface side). Note that the above-described frame portion 11, weight portion 12, and each bending portion 13 of the sensor substrate 1 may be formed using a lithography technique and an etching technique.

  By the way, as shown in the lower right of each of FIGS. 9A and 9B, one direction along one side of the frame portion 11 in a plane parallel to the one surface of the sensor substrate 1 is the positive direction of the x axis. If one direction along the side orthogonal to the one side is defined as the positive direction of the y-axis and one direction of the thickness direction of the sensor substrate 1 is defined as the positive direction of the z-axis, the weight portion 12 is extended in the x-axis direction. The pair of flexible portions 13 and 13 sandwiching the core portion 12a and the pair of flexible portions 13 and 13 extending in the y-axis direction and sandwiching the core portion 12a are supported by the frame portion 11. Will be. In the orthogonal coordinates defined by the three axes of the above-described x axis, y axis, and z axis, the center position of the weight portion 12 on the surface of the portion of the sensor substrate 1 formed by the silicon layer 10c is the origin.

  The bending portion 13 (the bending portion 13 on the right side of FIG. 9A) extending from the core portion 12a of the weight portion 12 in the positive direction of the x-axis is a pair of piezoresistors Rx2 and Rx4 in the vicinity of the core portion 12a. Is formed, and one piezoresistor Rz2 is formed in the vicinity of the frame portion 11. On the other hand, the bending portion 13 (the bending portion 13 on the left side of FIG. 9A) extended from the core portion 12a of the weight portion 12 in the negative direction of the x-axis is a pair of piezoresistors Rx1 in the vicinity of the core portion 12a. , Rx3 are formed, and one piezoresistor Rz3 is formed in the vicinity of the frame portion 11. Here, the four piezoresistors Rx1, Rx2, Rx3, and Rx4 formed in the vicinity of the core portion 12a are formed to detect acceleration in the x-axis direction, and the planar shape is an elongated rectangular shape. The wiring is formed so that the longitudinal direction thereof coincides with the longitudinal direction of the bending portion 13, and wiring (diffuse layer wiring formed on the sensor substrate 1, metal wiring 17 is formed so as to constitute the left bridge circuit Bx in FIG. 12. Etc.). Note that the piezoresistors Rx1 to Rx4 are formed in a stress concentration region where stress is concentrated in the bent portion 13 when acceleration in the x-axis direction is applied.

  Further, the bending portion 13 (the upper bending portion 13 in FIG. 9A) extending from the core portion 12a of the weight portion 12 in the positive direction of the y-axis is a pair of piezoresistors Ry1, in the vicinity of the core portion 12a. Ry3 is formed, and one piezoresistor Rz1 is formed in the vicinity of the frame portion 11. On the other hand, the bending portion 13 (the lower bending portion 13 in FIG. 9A) extending from the core portion 12a of the weight portion 12 in the negative direction of the y-axis is a pair of piezoresistors Ry2 in the vicinity of the core portion 12a. , Ry4 are formed, and one piezoresistor Rz4 is formed at the end on the frame part 11 side. Here, the four piezoresistors Ry1, Ry2, Ry3, and Ry4 formed in the vicinity of the core portion 12a are formed to detect acceleration in the y-axis direction, and the planar shape is an elongated rectangular shape. The wiring is formed so that the longitudinal direction coincides with the longitudinal direction of the bending portion 13, and the wiring (the diffusion layer wiring formed on the sensor substrate 1, the metal wiring 17 is formed so as to form the central bridge circuit By in FIG. 12. Etc.). Note that the piezoresistors Ry1 to Ry4 are formed in a stress concentration region where stress is concentrated in the flexure 13 when acceleration in the y-axis direction is applied.

  Further, the four piezoresistors Rz1, Rz2, Rz3, and Rz4 formed in the vicinity of the frame portion 11 are formed to detect acceleration in the z-axis direction, and constitute the right bridge circuit Bz in FIG. Thus, they are connected by wiring (a diffusion layer wiring formed on the sensor substrate 1, a metal wiring 17 or the like). However, the piezoresistors Rz1 and Rz4 formed in one set of the bent portions 13 and 13 of the two bent portions 13 and 13 are formed so that the longitudinal direction thereof coincides with the longitudinal direction of the bent portions 13 and 13. On the other hand, the piezoresistors Rz2 and Rz3 formed in the other set of flexures 13 and 13 are formed such that the longitudinal direction coincides with the width direction (short direction) of the flexures 13 and 13. Yes.

  7-9, only the site | part of the metal wiring 17 in the sensor board | substrate 1 vicinity of the 1st joining metal layer 19 for connection is shown in figure, and illustration of a diffused layer wiring is abbreviate | omitted.

  Here, an example of the operation of the sensor substrate 1 will be described.

  Now, assuming that acceleration is applied to the sensor substrate 1 in the positive x-axis direction while no acceleration is applied to the sensor substrate 1, the frame portion 11 is caused by the inertial force of the weight 12 acting in the negative x-axis direction. Accordingly, the weight 12 is displaced, and as a result, the bending portions 13 and 13 whose longitudinal direction is the x-axis direction are bent, and the resistance values of the piezoresistors Rx1 to Rx4 formed in the bending portions 13 and 13 are changed. Will do. In this case, the piezoresistors Rx1 and Rx3 are subjected to tensile stress, and the piezoresistors Rx2 and Rx4 are subjected to compressive stress. In general, a piezoresistor has a characteristic that a resistance value (resistivity) increases when subjected to a tensile stress, and a resistance value (resistivity) decreases when subjected to a compressive stress. Therefore, the piezoresistors Rx1 and Rx3 are resistant. The value increases, and the resistance values of the piezoresistors Rx2 and Rx4 decrease. Therefore, if a constant DC voltage is applied from the external power supply between the pair of input terminals VDD and GND shown in FIG. 12, the potential difference between the output terminals X1 and X2 of the left bridge circuit Bx shown in FIG. It changes according to the magnitude of the acceleration in the x-axis direction. Similarly, when acceleration in the y-axis direction is applied, the potential difference between the output terminals Y1 and Y2 of the central bridge circuit By shown in FIG. 12 changes according to the magnitude of acceleration in the y-axis direction, and the z-axis When the acceleration in the direction is applied, the potential difference between the output terminals Z1 and Z2 of the right bridge circuit Bz shown in FIG. 12 changes according to the magnitude of the acceleration in the z-axis direction. Thus, the above-described sensor substrate 1 detects the change in the output voltage of each of the bridge circuits Bx to Bz, so that the acceleration in the x-axis direction, the y-axis direction, and the z-axis direction that acted on the sensor substrate 1 is detected. Can be detected. In this embodiment, the weight part 12 and each bending part 13 comprise a movable part, and each piezoresistor Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4 constitutes a sensing part in the sensor substrate 1. Yes.

  By the way, as shown in FIG. 12, the sensor substrate 1 includes two input terminals VDD and GND common to the three bridge circuits Bx, By, and Bz described above, two output terminals X1 and X2 of the bridge circuit Bx, Two output terminals Y1 and Y2 of the bridge circuit By and two output terminals Z1 and Z2 of the bridge circuit Bz are provided. These input terminals VDD and GND and output terminals X1, X2, Y1, Y2, and the like. Z1 and Z2 are provided as the first connection bonding metal layer 19 on the one surface side (that is, the through hole wiring forming substrate 2 side), and the through hole wiring 24 formed on the through hole wiring forming substrate 2 is provided. And are electrically connected. That is, eight connecting metal layers 19 for connection are formed on the sensor substrate 1, and eight through-hole wirings 24 are formed on the through-hole wiring forming substrate 2. Note that the eight first connecting bonding metal layers 19 have a rectangular outer peripheral shape (in this embodiment, a square shape) and are spaced apart in the circumferential direction of the frame portion 11 (rectangular frame shape). 2 are arranged on each of the four sides of the frame part 11).

  In addition, a frame-shaped (rectangular frame-shaped) first sealing bonding metal layer 18 having a larger opening area than the frame portion 11 is formed on the frame portion 11 of the sensor substrate 1. The connection bonding metal layer 19 is disposed inside the first sealing bonding metal layer 18 in the frame portion 11. In short, the sensor substrate 1 is set so that the width dimension of the first sealing bonding metal layer 18 is smaller than the width dimension of the frame portion 11, and the first sealing bonding metal layer 18 and each connecting bonding metal. The layer 19 is formed on the same plane.

  Here, in the sensor substrate 1, an insulating film 16 made of a laminated film of a silicon oxide film and a silicon nitride film is formed on the silicon layer 10c on the one surface side, and a first connecting bonding metal layer 19 is formed. The first sealing bonding metal layer 18 and the metal wiring 17 are formed on the same level surface of the insulating film 16 with the same thickness.

  In addition, the first sealing bonding metal layer 18 and the first connecting bonding metal layer 19 have an adhesion improving Ti film interposed between the bonding Au film and the insulating film 16. In other words, the first sealing bonding metal layer 18 and the first connecting bonding metal layer 19 are composed of a Ti film formed on the same level surface of the insulating film 16 and an Au film formed on the Ti film. And a laminated film. In short, since the first connecting bonding metal layer 19 and the first sealing bonding metal layer 18 are formed of the same metal material, the first connecting bonding metal layer 19 and the first sealing metal layer 19 are formed. The first bonding metal layer 19 and the first sealing bonding metal layer 18 can be formed to have the same thickness. The first sealing bonding metal layer 18 and the first connecting bonding metal layer 19 have a Ti film thickness of 15 to 50 nm and an Au film thickness of 500 nm. The film thickness is set to 1 μm, but these numerical values are merely examples and are not particularly limited. Here, the material of each Au film is not limited to pure gold, and may be added with impurities. In this embodiment, a Ti film is interposed as an adhesion layer for improving adhesion between each Au film and the insulating film 16. However, the material of the adhesion layer is not limited to Ti, and, for example, Cr, Nb Zr, TiN, TaN, etc. may be used.

  Each of the above-described piezoresistors Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4, and each of the diffusion layer wirings is formed by doping a p-type impurity with an appropriate concentration in each formation site in the silicon layer 10c. The metal wiring 17 described above is formed by patterning a metal film (for example, an Al film, an Al alloy film, etc.) formed on the insulating film 16 by sputtering or vapor deposition using lithography technology and etching technology. The metal wiring 17 is electrically connected to the diffusion layer wiring through a contact hole provided in the insulating film 16. Further, the first connecting metal layer 19 for connection and the metal wiring 17 are formed so that the connecting portion 19b (see FIG. 8B) with the metal wiring 17 in the first connecting metal layer for connection 19 is formed as a through-hole wiring. The substrate 2 is electrically connected so as to be positioned in a later-described displacement space forming recess 21 formed on the surface of the substrate 2 facing the sensor substrate 1.

  As shown in FIGS. 13 to 15, the through-hole wiring forming substrate 2 is formed on the surface on the sensor substrate 1 side (the lower surface side in FIG. 7B) with the weight portion 12 and each bending portion 13 of the sensor substrate 1. The above-mentioned displacement space forming recesses 21 that secure the displacement space of the movable portion that is configured are formed, and a plurality (eight in the present embodiment) penetrates in the thickness direction in the peripheral portion of the displacement space formation recesses 21. Through-holes 22 are formed, and an insulating film 23 made of a thermal insulating film (silicon oxide film) is formed across both surfaces in the thickness direction and the inner surface of the through-holes 22. A part of the insulating film 23 is interposed between the inner surface and the inner surface. Here, the eight through-hole wirings 24 of the through-hole wiring forming substrate 2 are formed apart from each other in the circumferential direction of the through-hole wiring forming substrate 2. Moreover, although Cu is adopted as the material of the through-hole wiring 24, it is not limited to Cu, and for example, Ni may be adopted.

  In addition, the through-hole wiring forming substrate 2 has a plurality (eight in this embodiment, eight) electrically connected to the respective through-hole wirings 24 on the periphery of the displacement space forming concave portion 21 on the surface on the sensor substrate 1 side. ) Second connecting bonding metal layer 29 is formed. The through-hole wiring forming substrate 2 has a frame-shaped (rectangular frame-shaped) second sealing bonding metal layer 28 formed around the entire periphery of the surface on the sensor substrate 1 side. The eight second connecting bonding metal layers 29 have a rectangular shape whose outer peripheral shape is an elongated shape, and are disposed on the inner side of the second sealing bonding metal layer 28. Here, one end of the second connection bonding metal layer 29 is bonded to the through-hole wiring 24, and the other end side is outside the metal wiring 17 of the sensor substrate 1 and the sensor substrate 1. The first connecting bonding metal layer 19 is bonded and electrically connected. In short, the positions of the through-hole wiring 24 and the first connecting bonding metal layer 19 corresponding to the through-hole wiring 24 are shifted in the circumferential direction of the through-hole wiring forming substrate 2, and the second connecting bonding metal layer 29 is arranged such that the longitudinal direction thereof coincides with the circumferential direction of the second sealing bonding metal layer 28 and straddles the through-hole wiring 24 and the first connecting bonding metal layer 19.

  The second sealing bonding metal layer 28 and the second connecting bonding metal layer 29 have a Ti film for improving adhesion between the bonding Au film and the insulating film 23. In other words, the second sealing bonding metal layer 28 and the second connecting bonding metal layer 29 include a Ti film formed on the same level surface of the insulating film 23 and an Au film formed on the Ti film. And a laminated film. In short, since the second connecting bonding metal layer 29 and the second sealing bonding metal layer 28 are formed of the same metal material, the second connecting bonding metal layer 29 and the second sealing metal layer 29 are formed. The bonding metal layer 28 can be formed at the same time, and the second bonding metal layer 29 for connection and the second bonding metal layer 28 for sealing can be formed to the same thickness. The second sealing bonding metal layer 28 and the second connecting bonding metal layer 29 have a Ti film thickness of 15 to 50 nm and an Au film thickness of 500 nm. The numerical value is an example and is not particularly limited. Here, the material of each Au film is not limited to pure gold, and may be added with impurities. In the present embodiment, a Ti film is interposed as an adhesion improving adhesive layer between each Au film and the insulating film 23. However, the material of the adhesion layer is not limited to Ti, and, for example, Cr, Nb Zr, TiN, TaN, etc. may be used.

  A plurality of external connection electrodes 25 electrically connected to the respective through-hole wirings 24 are formed on the surface of the through-hole wiring forming substrate 2 opposite to the sensor substrate 1 side. Here, each external connection electrode 25 is constituted by a laminated film of a Ti film, a Cu film, a Ni film, and an Au film laminated in the thickness direction, and the uppermost layer is an Au film. The outer peripheral shape of each external connection electrode 25 is rectangular.

  As shown in FIG. 16, the cover substrate 3 is formed with a recess 31 having a predetermined depth (for example, about 5 μm to 10 μm) that forms a displacement space of the weight portion 12 on the surface facing the sensor substrate 1. Here, the recess 31 is formed using a lithography technique and an etching technique. In the present embodiment, the concave portion 31 that forms the displacement space of the weight portion 12 is formed on the surface of the cover substrate 3 that faces the sensor substrate 1, but the core portion 12a and each associated portion 12b of the weight portion 12 are formed. The thickness of the portion formed using the support substrate 10a of the sensor substrate 1 is compared with the thickness of the portion formed using the support substrate 10a in the frame portion 11 in the thickness direction of the sensor substrate 1. If the weight 12 is made thinner by the allowable displacement amount, the weight portion in the direction intersecting the other surface is formed on the other surface side of the sensor substrate 1 without forming the recess 31 in the cover substrate 3. A gap that enables the displacement of 12 is formed between the weight portion 12 and the cover substrate 3.

  By the way, the sensor substrate 1 and the through-hole wiring formation substrate 2 in the sensor element A described above are bonded to the first sealing bonding metal layer 18 and the second sealing bonding metal layer 28, The first connecting bonding metal layer 19 and the second connecting bonding metal layer 29 are bonded to each other, and the sensor substrate 1 and the cover substrate 3 are bonded to each other on the peripheral portions of the opposing surfaces. The sensor element A in this embodiment includes an SOI wafer on which a large number of sensor substrates 1 are formed, a first silicon wafer on which a large number of through-hole wiring forming substrates 2 are formed, and a second silicon wafer on which a large number of cover substrates 3 are formed. Are bonded to each other at a wafer level and then cut into acceleration sensor elements having a desired chip size by a dicing process. Therefore, the through-hole wiring forming substrate 2 and the cover substrate 3 have the same outer size as the sensor substrate 1, and a small chip size package can be realized and manufacture is facilitated.

  Here, as a method for bonding the sensor substrate 1 to the through-hole wiring forming substrate 2 and the cover substrate 3, it is desirable to employ a bonding method that enables bonding at a lower temperature in order to reduce the residual stress of the sensor substrate 1. In this embodiment, a room temperature bonding method is employed. In the room temperature bonding method, before bonding, each bonding surface is irradiated with argon plasma, ion beam or atomic beam in vacuum to clean and activate each bonding surface, and then the bonding surfaces are brought into contact with each other. Join at room temperature. In the present embodiment, the first sealing bonding metal layer 18 and the second sealing bonding metal layer 28 are bonded by applying an appropriate load at normal temperature by the above-described normal temperature bonding method. At the same time, the first connection bonding metal layer 19 and the second connection bonding metal layer 29 are bonded, and the frame portion 11 and the cover substrate of the sensor substrate 1 are bonded at room temperature by the room temperature bonding method described above. 3 circumferences are joined. Thus, in the sensor element A according to the present embodiment, the bonding between the sensor substrate 1 and the through-hole wiring substrate 2 is an Au—Au bonding, and the bonding between the sensor substrate 1 and the cover substrate 3 is an Si—Si bonding. ing. In the present embodiment, since the sensor substrate 1, the through-hole wiring formation substrate 2, and the cover substrate 3 are formed of Si, which is the same semiconductor material, the sensor substrate 1, the through-hole wiring formation substrate 2, and the cover substrate 3 are used. The stress (residual stress in the sensor substrate 1) due to the difference in linear expansion coefficient with respect to the output signal of the bridge circuit can be reduced, and the through-hole wiring forming substrate 2 and the cover substrate 3 are made of a material different from that of the sensor substrate 1. Compared with the case where it is formed, variation in sensor characteristics can be reduced. The sensor substrate 1 is formed by processing an SOI wafer. However, the sensor substrate 1 is not limited to an SOI wafer, and may be formed by processing a silicon wafer, for example.

  The IC chip 4 described above is integrated with an amplifier circuit that amplifies the output signal of the sensor element A, an offset adjustment circuit that adjusts an offset (offset voltage) of the output signal, a temperature compensation circuit that performs temperature compensation of the output signal, and the like. ASIC (Application Specific IC), which is formed using a silicon wafer.

  By the way, as shown in FIGS. 1 to 3, the acceleration sensor module of the present embodiment includes a package 5 having a rectangular tubular substrate 5 a on which the sensor element A is disposed, and an axis of the tubular substrate 5 a. And a rectangular plate-like plate substrate 5b that closes one end side in the direction. The sensor element A is flip-chip mounted on one surface side (the lower surface side of FIG. 1B) of the plate-like substrate 5b, and others. The IC chip 4 is flip-chip mounted on the surface side (the upper surface side in FIG. 1B), and the external circuit connection terminal 55 electrically connected to the wiring is the other end side in the axial direction of the cylindrical substrate 5a. Is formed.

  Here, the plate-like substrate 5b is composed of a flexible printed wiring board (FPC), and each external connection electrode 25 of the sensor element A is electrically connected to the one surface side via a bump (Au bump) 9. A plurality of sensor connection electrodes 53 to be connected and a plurality of inter-substrate coupling electrodes 57 to be described later are formed, and each pad 41 of the IC chip 4 is provided on each other surface via bumps (Au bumps) 7. A plurality of IC connection electrodes 54 to be electrically connected are formed, and the sensor connection electrode 53 and the IC connection electrode 54 are electrically connected so that the sensor element A and the IC chip 4 have a predetermined connection relationship. A plurality of through-hole plating portions to be connected are formed, and these through-hole plating portions constitute a part of the wiring. In the present embodiment, the former bump 9 is constituted by a stud bump formed on the sensor connection electrode 53 by a stud bump method. Further, the latter bump 7 is constituted by a stud bump formed by the stud bump method on the IC connection electrode 54, but may be constituted by a plating bump formed by a plating method. Each sensor connection electrode 53, each inter-substrate bonding electrode 57, and each IC connection electrode 54 are composed of a laminated film of a Cu film, a Ni film, and an Au film laminated in the thickness direction. Is an Au film.

  On the other hand, the cylindrical substrate 5a is made of a ceramic substrate, and a plurality of inter-substrate coupling electrodes 56 for mechanically and electrically connecting the plate-like substrate 5a are formed on one end side in the axial direction. A plurality of terminals (lead electrodes) 55 for connecting an external circuit are formed on the other axial end of the cylindrical substrate 5a, and a conductor pattern for electrically connecting the inter-substrate coupling electrode 56 and the terminal 55 is embedded. The conductor pattern constitutes the wiring together with the through-hole plating part. Here, the cylindrical substrate 5a and the plate-like substrate 5b are formed by soldering a plurality of inter-substrate coupling electrodes 56 of the cylindrical substrate 5a and a plurality of inter-substrate coupling electrodes 57 of the plate-like substrate 5b (for example, SnAgCu or the like). And mechanically and electrically coupled to each other through a joint 58 made of lead-free solder). Each inter-substrate coupling electrode 56 and each terminal 55 are composed of a laminated film of a W film, an Ni film, and an Au film laminated in the thickness direction, and the uppermost layer is an Au film.

  When the acceleration sensor module of the present embodiment is used by being mounted on a circuit board such as a printed circuit board, the circuit pattern on the circuit board and the terminal 55 are joined using solder (for example, lead-free solder such as SnAgCu). do it.

  Hereinafter, a method for manufacturing the acceleration sensor module of the present embodiment will be described with reference to FIGS.

  First, a sheet-like underfill resin material 81 made of an uncured thermosetting resin is attached to the other surface side (upper surface side of FIG. 5A) of the plate-like substrate 5b shown in FIG. The structure shown in FIG.5 (b) is obtained by performing the resin material sticking process to perform. In the resin material attaching step, an appropriate load is applied in a state where the underfill resin material 81 is appropriately heated to a temperature.

  Next, after aligning the bumps 7 (see FIG. 6) made of stud bumps formed in advance on the pads 41 of the IC chip 4 with the IC connection electrodes 54 of the plate-like substrate 5b, the IC chip 4 and The bump 7 on the pad 41 of the IC chip 4 is formed by heating and applying a load to the IC chip 4 with the underfill resin material 81 interposed between the other surface of the plate-like substrate 5b. The structure shown in FIG. 5C is obtained by performing an IC mounting step of forming the underfill 8 by thermosetting the resin material 81 for underfill at the same time as thermocompression bonding to the IC connection electrode 54 of the substrate 5b. Get. In short, in the IC mounting process, the IC chip 4 is flip-chip mounted on the other surface side of the plate-like substrate 5b. The bumps 7 are not limited to stud bumps, and may be plated bumps.

  Thereafter, as shown in FIG. 4 (a), solder to be a joint 58 is applied on the inter-substrate coupling electrode 56 of the cylindrical substrate 5a, and then the substrate of the plate-like substrate 5b in the state of FIG. 5 (c). The plate-like substrate 5b and the cylindrical substrate 5a are mechanically and electrically connected by aligning the inter-electrode 57 and the inter-substrate coupling electrode 56 of the cylindrical substrate 5a and performing reflow (solder mounting). The structure shown in FIG. 4B is obtained by performing the inter-substrate bonding step for bonding to the substrate.

  Next, by performing a bump forming step for forming bumps 9 made of stud bumps by the stud bump method on the one surface side of the plate-like substrate 5b, the structure shown in FIG. 4C is obtained.

  Thereafter, the bumps 9 formed on the external connection electrode 25 of the sensor element A and the sensor connection electrode 53 of the plate-like substrate 5b are each irradiated with argon plasma, ion beam or atomic beam in vacuum to clean the surface. After performing the activation process to be activated, the external connection electrode 25 and the bump 9 of the sensor element A are aligned, and a load is applied to the sensor element A at room temperature to thereby apply the external connection electrode 25 and the bump. By performing a sensor mounting process in which the sensor 9 is bonded at room temperature, an acceleration sensor module having a structure shown in FIG. 4D is obtained. In short, in the sensor mounting process, the sensor element A is flip-chip mounted on the one surface side of the plate-like substrate 5b.

  In the acceleration sensor module of the present embodiment described above, the sensor element A and the IC chip 4 are formed on the inner side of the package 5 in which the wiring for connecting the sensor element A and the IC chip 4 to the external circuit is formed and the sensor element A is accommodated. A cylindrical substrate 5a and a plate-like substrate 5b arranged on the one end side in the axial direction of the cylindrical substrate 5a. The sensor element A is flip-chip mounted on the one surface side of the plate-like substrate 5b. Since the IC chip 4 is flip-chip mounted on the other surface side, and an external circuit connection terminal 55 electrically connected to the wiring is formed on the other end side in the axial direction of the cylindrical substrate 5a. Compared with the conventional configuration shown in FIG. 19, the mounting area on the circuit board can be further reduced without reducing the planar size of the IC chip 4.

  According to the method for manufacturing the acceleration sensor module described above, since the external connection electrodes 25 and the bumps 9 of the sensor element A having a small planar size are bonded at room temperature in the sensor mounting process, the sensor element A and the plate The residual stress due to the difference in linear expansion coefficient with the substrate 5b can be reduced, and fluctuations in sensor characteristics of the sensor element A can be suppressed. Further, when the sensor element A is mounted on the plate-like substrate 5b, since the underfill 8 is interposed between the IC chip 4 and the plate-like substrate 5b, the IC chip is applied when a load is applied to the sensor element A. 4 can be prevented from being damaged or the connection reliability between the IC chip 4 and the plate-like substrate 5b can be prevented, and the connection reliability between the bump 9 and the sensor connection electrode 53 can be increased. The connection reliability between A and the plate-like substrate 5b can be improved.

(Embodiment 2)
The basic configuration of the sensor module of the present embodiment is the same as that of the acceleration sensor module of the first embodiment, and the manufacturing method is different. Therefore, the manufacturing method will be described with reference to FIGS. 17 and 18. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted suitably about the process similar to Embodiment 1 also about a manufacturing method.

  First, a sheet-like underfill resin material 81 made of an uncured thermosetting resin is attached to the other surface side (upper surface side of FIG. 18A) of the plate-like substrate 5b shown in FIG. The structure shown in FIG.18 (b) is obtained by performing the resin material sticking process to perform.

  Next, after aligning the bumps 7 (see FIG. 6) made of stud bumps formed in advance on the pads 41 of the IC chip 4 with the IC connection electrodes 54 of the plate-like substrate 5b, the IC chip 4 and The bump 7 on the pad 41 of the IC chip 4 is formed by heating and applying a load to the IC chip 4 with the underfill resin material 81 interposed between the other surface of the plate-like substrate 5b. 18C by performing an IC mounting process for forming the underfill 8 by thermosetting the resin material 81 for underfill at the same time as thermocompression bonding to the IC connection electrode 54 of the substrate 5b. Get.

  Subsequently, by performing a bump forming step of forming bumps 9 made of stud bumps by the stud bump method on the one surface side of the plate-like substrate 5b, the structure shown in FIG. 18D is obtained.

  Thereafter, as shown in FIG. 17 (a), solder to be the joining portion 58 is applied onto the inter-substrate coupling electrode 56 of the cylindrical substrate 5a, and then the substrate of the plate-like substrate 5b in the state of FIG. 18 (d). The plate-like substrate 5b and the cylindrical substrate 5a are mechanically and electrically connected by aligning the inter-electrode 57 and the inter-substrate coupling electrode 56 of the cylindrical substrate 5a and performing reflow (solder mounting). The structure shown in FIG. 17B is obtained by performing the inter-substrate bonding step for bonding to the substrate.

  Next, the surface of the bump 9 formed on the external connection electrode 25 of the sensor element A and the sensor connection electrode 53 of the plate-like substrate 5b is irradiated with argon plasma, ion beam or atomic beam in vacuum to clean the surface. The external connection electrode 25 and the bump 9 of the sensor element A are aligned with each other and a load is applied to the sensor element A at room temperature after performing the activation process of activation / activation. An acceleration sensor module having a structure shown in FIG. 17C is obtained by performing a sensor mounting process for bonding the bumps 9 at room temperature. In short, in the sensor mounting process, the sensor element A is flip-chip mounted on the one surface side of the plate-like substrate 5b.

  In short, in the method of manufacturing the acceleration sensor module according to the present embodiment, a bump forming step of forming the sensor element mounting bumps 9 on the one surface side of the plate-like substrate 5b is performed between the IC mounting step and the inter-substrate coupling step. This is different from the manufacturing method described in the first embodiment.

  Thus, according to the method of manufacturing the acceleration sensor module of the present embodiment, when the bumps 9 for mounting the sensor elements are formed on the one surface side of the plate-like substrate 5b by the stud bump method, the substrate as in the first embodiment is used. Compared with the case where the bumps 9 are formed after the inter-bonding process, the formation of the bumps 9 becomes easier.

  By the way, in each above-mentioned embodiment, although the flexible printed wiring board is used as the plate-shaped board | substrate 5b, the plate-shaped board | substrate 5b is not restricted to a flexible printed wiring board, For example, you may use a silicon substrate.

  In each embodiment, the piezoresistive acceleration sensor element is exemplified as the sensor element that is the sensor element A. However, the technical idea of the present invention is not limited to the piezoresistive acceleration sensor element. It can also be applied to other sensor elements such as acceleration sensor elements and gyro sensor elements. In capacitive acceleration sensor elements and gyro sensor elements, the weight part with a movable electrode or the weight part that also serves as the movable electrode constitutes the movable part. The sensing unit is constituted by the fixed electrode and the movable electrode.

The acceleration sensor module of Embodiment 1 is shown, (a) is a schematic plan view, (b) is a schematic sectional drawing. It is a schematic bottom view of an acceleration sensor module same as the above. It is the schematic perspective view which a part of acceleration sensor module same as the above fractured. It is principal process sectional drawing for demonstrating the manufacturing method of an acceleration sensor module same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of an acceleration sensor module same as the above. It is explanatory drawing of the manufacturing method of an acceleration sensor module same as the above. The sensor element in the same as above is shown, (a) is a schematic plan view, (b) is a D-D 'schematic sectional view of (a). The sensor element in the same as above is shown, (a) is an enlarged view of the main part of FIG. 7 (b), (b) is a schematic cross-sectional view of C-C 'of FIG. 7 (a). The sensor board | substrate in the same is shown, (a) is a schematic plan view, (b) is B-D 'schematic sectional drawing of (a). The sensor board | substrate in the same as the above is shown, (a) is D-D 'schematic sectional drawing of Fig.9 (a), (b) is C-C' schematic sectional drawing of Fig.9 (a). It is a schematic bottom view which shows the sensor board | substrate in the same as the above. It is a circuit diagram of the sensor board | substrate in the same as the above. The through-hole wiring formation board | substrate in the same as the above is shown, (a) is a schematic plan view, (b) is D-D 'schematic sectional drawing of (a). The through-hole wiring formation board | substrate in the same as the above is shown, and it is the principal part enlarged view of FIG.13 (b). It is a bottom view of the through-hole wiring formation board in the same as the above. The cover board | substrate in the same as the above is shown, (a) is a schematic plan view, (b) is D-D 'schematic sectional drawing of (a). It is a main process sectional view for explaining the manufacturing method of the acceleration sensor module of Embodiment 2. It is principal process sectional drawing for demonstrating the manufacturing method of an acceleration sensor module same as the above. It is a schematic sectional drawing which shows a prior art example.

Explanation of symbols

A sensor element 4 IC chip 5 package 5a cylindrical substrate 5b plate substrate 8 underfill 55 terminal

Claims (3)

  An IC chip on which a sensor element, a signal processing circuit for processing an output signal of the sensor element are formed, and a package in which wiring for connecting the sensor element and the IC chip to an external circuit is formed and the sensor element is stored The package includes a cylindrical substrate on which the sensor element is disposed on the inside and a plate-shaped substrate disposed on one end side in the axial direction of the cylindrical substrate, and the sensor element is flipped on one surface side of the plate-shaped substrate. In addition to chip mounting, an IC chip is flip-chip mounted on the other surface side, and an external circuit connection terminal electrically connected to the wiring is formed on the other end side in the axial direction of the cylindrical substrate. A sensor module.   2. The sensor module manufacturing method according to claim 1, wherein an IC mounting step of flip-chip mounting an IC chip on the other surface side of the plate-shaped substrate, and a plate-shaped substrate and a cylindrical substrate after the IC mounting step are performed. A sensor module comprising: an inter-substrate coupling step for mechanically and electrically coupling; and a sensor mounting step for flip-chip mounting a sensor element on the one side of the plate-like substrate after the inter-substrate coupling step. Production method.   Between the IC mounting step and the inter-substrate coupling step, a bump forming step of forming a bump for mounting a sensor element on the one surface side of the plate-like substrate is provided, and in the sensor mounting step, the sensor element is 3. The method of manufacturing a sensor module according to claim 2, wherein flip chip mounting is performed on the plate-like substrate through bumps formed in a bump forming step.

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