JP4967537B2 - Sensor unit and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sensor unit, and more particularly, to a sensor unit equipped with a resistance element and capable of detecting pressure or acceleration, and a method for easily manufacturing the sensor unit.

Conventionally, a sensor unit including an image sensor such as a CCD or CMOS, a sensor such as an acceleration sensor, and an active element that controls the sensor has been used for various applications. As such a sensor unit, for example, a sensor built-in module and an active element built-in module are mounted on a wiring board by using connection means such as wire bonding or metal bump, and these are protected by resin sealing. (Patent Document 1).
On the other hand, various sensors have been developed as sensors for detecting pressure or acceleration acting on an object (Patent Documents 2 and 3).
JP 2003-259169 A JP 2002-221463 A JP 2004-69405 A

However, in the conventional sensor unit as described above, since the sensor built-in module mounted on the wiring board is located in a part different from the mounting part of the active element built-in module, it is necessary to expand the surface direction of the wiring board. Met. For this reason, there was a limit to downsizing the sensor unit.
In addition, since the sensor built-in module and the active element built-in module are individually mounted on the wiring board, it is necessary to accurately align each module for mounting at a predetermined position on the wiring board, and the process management is complicated. In addition, when the mounting position is shifted, there is a problem that the reliability of the sensor unit is lowered.
In addition, the sensor may be exposed to high temperatures during mounting, which may cause deterioration in sensor characteristics and sensor unit reliability.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a small and highly reliable sensor unit and a manufacturing method for easily manufacturing such a sensor unit. .

  In order to achieve such an object, a sensor unit of the present invention includes a sensor using a piezoresistive element and an active element built-in module joined to the sensor, and the sensor includes a silicon layer / silicon oxide layer. / Consisting of an SOI substrate having a three-layer structure of a silicon layer, a frame member, a plurality of through electrodes penetrating the frame member, a plurality of beams protruding inward from the frame member, and supported by the beams A weight, a piezoresistive element disposed on the beam, and a wiring connecting the piezoresistive element and the through electrode, and the active so as to form a predetermined gap between the weight An element built-in module is joined to the frame member, and the active element built-in module is connected to a substrate having a built-in active element and having a plurality of through electrodes in a region outside the active element, and the through electrode. Wherein a wiring and arranged on a substrate, and the wiring has a configuration such as is joined to the through electrodes of the sensor.

  The sensor unit of the present invention includes a sensor using a piezoresistive element and an active element built-in module joined to the sensor, and the sensor has a three-layer structure of silicon layer / silicon oxide layer / silicon layer. An SOI substrate having a frame member, a plurality of through electrodes penetrating the frame member, a plurality of beams protruding inward from the frame member, a weight supported by the beam, and disposed on the beam A piezoresistive element, and a wiring connecting the piezoresistive element and the through electrode, and the module with a built-in active element includes a substrate with a built-in active element, and a wiring disposed on the substrate. The wiring is joined to the sensor wiring.

As another aspect of the present invention, the connection between the through electrode of the sensor and the wiring of the module with a built-in active element is configured through a bonding bump.
As another aspect of the present invention, the sensor wiring and the active element built-in module wiring are joined via a joint bump.
As another aspect of the present invention, the bonding bump is any one of Au, Sn—Au alloy, and Sn—Ag alloy, and a Cu / Cr stacked layer, a Cu / Ti stacked layer, an Al / Cr stacked so as to sandwich the bonding bump. It was set as the structure by which any metal layer of lamination | stacking and Al / Ti lamination | stacking was arrange | positioned.

  The sensor unit manufacturing method of the present invention divides an SOI wafer having a three-layer structure of silicon layer / silicon oxide layer / silicon layer into multiple impositions, performs desired processing for each imposition, and a frame member; A plurality of through electrodes penetrating the frame member; a plurality of beams protruding inward from the frame member; a weight supported by the beam; a piezoresistive element disposed on the beam; and the piezoresistor A step of fabricating a sensor having a wiring connecting an element and the through electrode by multi-sided attachment, and dividing the active element built-in module wafer into multi-sided attachment, and incorporating an active element for each imposition, A plurality of fine through-holes are formed in the outer region of the element, a conductive material is arranged in the fine through-hole to form a through-electrode, and a wiring connected to the through-electrode is formed, so that the active element built-in module is multifaceted And the process of making The wiring of the module with a built-in active element and the through electrode of the sensor are bonded by a bonding bump so that a predetermined gap is formed between the weight of the sensor and the module with a built-in active element. The sensor unit is configured to include a step of forming a sensor unit and a step of dicing the multi-sided sensor unit.

  In addition, the method for manufacturing a sensor unit according to the present invention divides an SOI wafer having a three-layer structure of a silicon layer / a silicon oxide layer / a silicon layer into multiple faces, performs desired processing for each face, A plurality of through electrodes penetrating the frame member, a plurality of beams projecting inward from the frame member, a weight supported by the beam, a piezoresistive element disposed on the beam, A step of fabricating a sensor having multi-sided attachment, a wiring having a wiring connecting the piezoresistive element and the through electrode, and a module element built-in module wafer are divided into multi-sided attachments, and an active element is built in each imposition. A multi-sided sensor is formed by forming a wiring and fabricating an active element built-in module by multi-sided attachment, and joining the active element built-in module wiring and the sensor wiring by joint bumps. And a step of a knit, a step of dicing the multi with the sensor unit, and that have configure.

Such a sensor unit of the present invention has a structure in which a sensor and a module with a built-in active element are joined, does not include a wiring board, and further, the sensor itself does not include a protective substrate. Significant downsizing is possible.
In addition, the manufacturing method of the present invention enables collective assembly in which the sensor and the active element built-in module are bonded at the wafer level, the process management is easy, and the manufacturing cost can be reduced. Since bumps are used and bonding at a low temperature is possible, the influence of heat on the piezoresistive element can be prevented, and a highly reliable sensor unit can be manufactured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Sensor unit]
FIG. 1 is a schematic cross-sectional view showing an embodiment of a sensor unit of the present invention. In FIG. 1, a sensor unit 1 of the present invention is obtained by bonding a sensor 2 and an active element built-in module 5 via bonding bumps 6.
The sensor 2 constituting the sensor unit 1 is a sensor using a piezoresistive element, and may be a conventionally known sensor such as a MEMS (Micro Electromechanical System) type pressure sensor or an acceleration sensor, and is not particularly limited. . In the illustrated example, the sensor 2 includes an SOI (Silicon On Insulator) substrate 11 having a three-layer structure in which a silicon oxide layer 13 is sandwiched between a silicon layer 12 (active layer silicon) and a silicon layer 14 (substrate silicon).
2 is a plan view from the silicon layer 14 (substrate silicon) side of the sensor 2 constituting the sensor unit 1 shown in FIG. 1, and FIG. 3 is a plan view from the silicon layer 12 (active layer silicon) side. It is. And the sensor 2 shown by FIG. 1 has shown the longitudinal cross-sectional shape in the II line | wire in FIG. 2 and FIG.

As shown in FIGS. 1 to 3, the sensor 2 includes a frame member 21, four beams 22 made of a silicon layer 12 (active layer silicon) and projecting inward from the frame member 21, and these four beams. A weight 23 supported by the beam 22. Therefore, there is a space region 24 (four regions 24A, 24B, 24C, 24D) partitioned by the frame member 21, each beam 22, and the weight 23.
The frame member 21 supports the weight 23 so as to be displaceable via the four beams 22, and is a member for joining the active element built-in module 5. In the illustrated example, the frame member 21 has a corridor shape, but is not limited thereto, and may be, for example, a circular shape. The frame member 21 includes a plurality (four in the illustrated example) of fine through holes 26 and through electrodes 27 disposed in the fine through holes 26. A terminal 28 is provided at the end of the through electrode 27 on the active element built-in module 5 side.

  Said fine through-hole 26 is 1-50 micrometers in opening diameter, Preferably it is about 5-30 micrometers. The shape of the fine through-hole 26 is a straight shape having a substantially constant inner diameter in the thickness direction in the illustrated example, but is not limited to this, and has a taper shape with one wide opening diameter, substantially at the center in the thickness direction. A shape or the like having a narrow inner diameter may be used. Further, the through electrode 27 disposed in the fine through hole 26 may be filled in the fine through hole 26, and is formed on the inner wall surface of the fine through hole 26 so that there is a through hole. It may be something like that. The material of the through electrode 27 can be a conductive material such as Au, Ag, Cu, or Sn.

Each of the beams 22 made of the silicon layer 12 (active layer silicon) includes the piezoresistive element 16 on the surface opposite to the surface facing the active element built-in module 5. Further, a desired piezoresistive element 16 and the through electrode 27 are connected by a wiring 18 disposed via an insulating layer 17. Furthermore, a protective layer 19 that covers the wiring 18 is provided. In FIG. 3, the insulating layer 17, the wiring 18, and the protective layer 19 are omitted. The piezoresistive element 16 is, for example, a P-type diffusion layer or an N-type diffusion layer formed by ion implantation or thermal diffusion of impurities such as boron into the silicon layer 12 (active layer silicon). The insulating layer 17 may be made of, for example, silicon oxide, silicon nitride or the like, and the protective layer 19 may be made of, for example, silicon nitride or the like.
The weight 23 has a three-layer structure of a silicon layer 12 (active layer silicon), a silicon oxide layer 13, and a silicon layer 14 (substrate silicon), but the silicon layer 14 (substrate silicon) has a thickness that constitutes the frame member 21. It is thinner than the layer 14 (substrate silicon). Thus, a predetermined gap exists between the active element built-in module 5 joined to the frame member 21 and the weight 23. The size of the gap can be set as appropriate within a range of about 3 to 20 μm, for example.

In the sensor 2 as described above, when an external force acts on the weight 23 supported by the four beams 22 in the X-axis, Y-axis, or Z-axis (see FIG. 1) direction, the weight 23 is displaced. Due to this displacement, the beam 22 is bent, and an external force acting on the weight 23 is detected by the piezoresistive element 16.
The active element built-in module 5 constituting the sensor unit 1 includes a substrate 31, an active element 45 built in the substrate 31, and a plurality of fine through holes 32 formed in the substrate 31 in a region outside the active element 45. And a through electrode 33 disposed in the fine through holes 32.
A wiring 34 is disposed on the surface of the substrate 31 facing the sensor 2, and an insulating layer 37 is disposed so as to cover the wiring 34. The wiring 34 is connected to a predetermined through electrode 33 and is connected to a terminal (not shown) of the active element 45. The insulating layer 37 has an opening 37a for exposing a desired portion of the wiring 34, and the bonding bump 6 is bonded to the wiring 34 exposed in the opening 37a.

A wiring 38 connected to a predetermined through electrode 33 is disposed on the surface of the substrate 31 opposite to the surface facing the sensor 2, and an insulating layer 41 is disposed so as to cover the wiring 38. Has been. In the insulating layer 41, wirings 40 are disposed through vias 39, and solder bumps 46 as external terminals are disposed at desired locations of the wirings 40.
Examples of the material of the substrate 31 include silicon and glass. The fine through hole 32 has an opening diameter of 1 to 50 μm, preferably about 5 to 30 μm. In the illustrated example, the shape of the fine through-hole 32 is a straight shape having a substantially constant inner diameter in the thickness direction, but is not limited to this. A shape or the like having a narrow inner diameter may be used.

The through electrode 33 disposed in the fine through hole 32 as described above may be filled in the fine through hole 32, and is formed on the inner wall surface of the fine through hole 32. May exist. The material of the through electrode 33 can be a conductive material such as Au, Ag, Cu, or Sn.
The wiring 34 of the active element built-in module 5 is bonded to the through electrode 27 (terminal 28) of the frame member 21 of the sensor 2 via the bonding bump 6.

  FIG. 4 is a partially enlarged cross-sectional view for explaining an example of bonding between the through electrode 27 (terminal 28) of the sensor 2 and the wiring 34 of the active element built-in module 5 via the bonding bump 6. In the example shown in FIG. 4, the terminal 28 that is a laminate of the metal layer 28 a and the metal layer 28 b and the wiring 34 that is a laminate of the metal layer 34 a and the metal layer 34 b are bonded via the bonding bumps 6. . As the terminal 28 that is a laminate of the metal layer 28a and the metal layer 28b, for example, an Al / Cr laminate, an Al / Ti laminate, or the like can be used. Moreover, as the wiring 34 which is lamination | stacking with the metal layer 34a and the metal layer 34b, it can be set as Cu / Cr lamination | stacking, Cu / Ti lamination | stacking, etc., for example. Note that the terminal 28 and the wiring 34 may be formed of a desired conductive material, and the metal layer as described above may be formed at a bonding portion by the bonding bump 6. For example, the terminal 28 is formed of Al, a metal layer such as Cr or Ti is formed at a bonding portion by the bonding bump 6, and the wiring 34 is formed by Cu, and the bonding portion by the bonding bump 6 is formed of Cr, Ti, or the like. A metal layer may be formed

The material of the bonding bump 6 can be, for example, Au, Sn—Au alloy, Sn—Ag alloy, or the like. The shape of the bonding bump 6 is not particularly limited, and can be appropriately set within a range of, for example, a height of 5 to 20 μm and a thickness of 10 to 100 μm. Bonding between the through electrode 27 (terminal 28) and the wiring 34 via the bonding bump 6 can be stably performed at a temperature of 400 ° C. or lower.
In the present invention, the bonding bump 6 may be bonded to the through electrode 27 without the terminal 28 interposed. In this case, for example, a metal layer such as an Al / Cr laminated layer or an Al / Ti laminated layer is formed at the tip of the through electrode 27 formed in the fine through hole 26, and this metal layer is exposed to the exposed surface (frame member). 21). Further, the through electrode 27 is made of Al, and a metal layer such as Cr or Ti is formed at the tip, so that the metal layer becomes an exposed surface of the through electrode 27 (surface exposed to the frame member 21). Also good.

FIG. 5 is a schematic cross-sectional view corresponding to FIG. 1 showing a sensor constituting another embodiment of the sensor unit of the present invention. A sensor unit 1 ′ shown in FIG. 5 is obtained by bonding a sensor 2 and an active element built-in module 5 ′ via bonding bumps 6.
In the sensor 2 constituting the sensor unit 1 ′, an opening 19 a is formed in the protective layer 19 that covers the wiring 18, and a desired portion of the wiring 18 is exposed in the opening 19 a. Except for the point that the bonding bump 6 is bonded, it is the same as the sensor 2 of the above-described embodiment, and the same member number is assigned to the same member. Therefore, in the sensor unit 1 ′, the bonding direction of the active element built-in module 5 ′ to the sensor 2 is opposite to the bonding direction of the active element built-in module 5 to the sensor 2 in the sensor unit 1 described above. In the illustrated example, solder bumps 29 as external terminals are disposed on the terminals 28 disposed on the frame member 21 of the sensor 2.

The active element built-in module 5 ′ constituting the sensor unit 1 ′ includes a substrate 31, an active element 45 built in the substrate 31, and a wiring 34 disposed on the surface of the substrate 31 facing the sensor 2. I have. The wiring 34 is connected to a terminal (not shown) of the active element 45, and an insulating layer 37 is disposed so as to cover the wiring 34. The insulating layer 37 has an opening 37a for exposing a desired portion of the wiring 34, and the bonding bump 6 is bonded to the wiring 34 exposed in the opening 37a. Examples of the material of the substrate 31 include silicon and glass.
The wiring 34 of the active element built-in module 5 ′ is bonded to the wiring 18 of the sensor 2 through the bonding bump 6.

FIG. 6 is a partially enlarged cross-sectional view for explaining an example of bonding between the wiring 18 of the sensor 2 and the wiring 34 of the active element built-in module 5 ′ via the bonding bump 6. In the example shown in FIG. 6, the wiring 18 that is a laminate of the metal layer 18 a and the metal layer 18 b and the wiring 34 that is a laminate of the metal layer 34 a and the metal layer 34 b are bonded via the bonding bumps 6. . As the wiring 18 that is a laminate of the metal layer 18a and the metal layer 18b, for example, an Al / Cr laminate, an Al / Ti laminate, or the like can be used. Moreover, as the wiring 34 which is lamination | stacking with the metal layer 34a and the metal layer 34b, it can be set as Cu / Cr lamination | stacking, Cu / Ti lamination | stacking, etc., for example. Note that the wiring 18 and the wiring 34 may be formed of a desired conductive material, and the metal layer as described above may be formed at a bonding portion by the bonding bump 6. For example, the wiring 18 is formed of Al, and a metal layer such as Cr or Ti is formed at the bonding portion by the bonding bump 6, and the wiring 34 is formed by Cu and the bonding portion by the bonding bump 6 is formed of Cr, Ti, or the like. The metal layer may be formed. The bonding bump 6 may be made of, for example, Au, Sn—Au alloy, Sn—Ag alloy, or the like. The shape of the bonding bump 6 is not particularly limited, and can be appropriately set within a range of, for example, a height of 5 to 20 μm and a thickness of 10 to 100 μm. The bonding between the wiring 18 of the sensor 2 and the wiring 34 of the active element built-in module 5 ′ via the bonding bump 6 can be stably performed at a temperature of 400 ° C. or lower.

7 is a schematic cross-sectional view corresponding to FIG. 1 showing a sensor constituting another embodiment of the sensor unit of the present invention, and FIGS. 8 and 9 are plan views of the sensor shown in FIG. This corresponds to FIG. 2 and FIG. In addition, the sensor shown in FIG. 7 has shown the longitudinal cross-sectional shape in the II-II line | wire in FIG. 8 and FIG.
The sensor 2 ′ shown in FIGS. 7 to 9 includes a silicon layer 12 in a space area 24 (four areas 24 A, 24 B, 24 C, and 24 D) defined by the frame member 21, the beams 22, and the weight 23. There are a restriction member 25 (four restriction members 25A, 25B, 25C, and 25D) made of (active layer silicon), and a central portion 23A in which the weight 23 is supported by four beams 22, and 4 Except for the point which consists of one protrusion part 23B, it is the same as that of the sensor 2 of the above-mentioned embodiment, and attaches | subjects the same member number to the same member.

  In this sensor 2 ′, the central portion 23 </ b> A constituting the weight 23 has a three-layer structure of a silicon layer 12 (active layer silicon), a silicon oxide layer 13, and a silicon layer 14 (substrate silicon). 23B is made of a silicon layer 14 (substrate silicon). In addition, the four protruding portions 23B protrude into the space area 24 (four areas 24A, 24B, 24C, and 24D), and exceed the space area, and the four regulating members 25A and 25B. , 25C, and 25D. A gap is formed between each protrusion 23B and the four regulating members 25A, 25B, 25C, and 25D. Thus, when an external force acts on the weight 23 supported by the four beams 22 in the X-axis, Y-axis, or Z-axis (see FIG. 7) direction, the weight 23 is displaced. However, when the external force acting on the weight 23 exceeds a predetermined allowable range, any of the four protrusions 23B of the weight 23 contacts any of the four restriction members 25A, 25B, 25C, 25D. Displacement is restricted. For this reason, it is possible to prevent the beam 22 from being damaged by an excessive external force.

FIG. 10 is a plan view corresponding to FIG. 3 and showing a sensor constituting another embodiment of the sensor unit of the present invention.
The sensor 2 ″ shown in FIG. 10 is the same as the sensor 2 of the above-described embodiment except that the number of the piezoresistive elements 16 arranged on the four beams 22 is twelve. The sensor 2 ″ has four piezoresistive elements 16x that detect external force in the X-axis direction, four piezoresistive elements 16y that detect external force in the Y-axis direction, And four piezoresistive elements 16z for detecting an external force in the Z-axis direction.
The embodiments of the sensor unit described above are examples, and the sensor unit of the present invention is not limited to these. For example, the position of the active element 45 built in the active element built-in module 5 may be a surface opposite to the surface of the substrate 31 facing the sensor 2.

[Method for manufacturing sensor unit]
Next, the manufacturing method of the sensor unit of this invention is demonstrated.
11 and 12 are process diagrams showing an embodiment of a method for manufacturing a sensor unit of the present invention, taking the sensor unit 1 shown in FIG. 1 as an example.
In the present invention, first, the sensor 2 is manufactured by multiple imposition. That is, an SOI (Silicon On Insulator) wafer 11A having a three-layer structure of a silicon layer 12 (active layer silicon), a silicon oxide layer 13, and a silicon layer 14 (substrate silicon) is multi-faced (each facet is indicated by 1A). (FIG. 11A). Then, desired processing is performed for each imposition 1A, and the sensor 2 is produced by multi-imposition (FIG. 11B). The sensor 2 includes a frame member 21, a plurality of through electrodes 27 penetrating the frame member 21, terminals 28 connected to the through electrodes 27, a plurality of beams 22 projecting inward from the frame member 21, The weight 23 supported by 22, the piezoresistive element 16 disposed on the beam 22, the wiring 18 connecting the piezoresistive element 16 and the through electrode 27, and the protective layer 19 covering the wiring 18. Have. The manufacturing process of the multi-sided sensor 2 will be described later.

Further, in the sensor unit manufacturing method of the present invention, the active element built-in module 5 is manufactured by multi-faceting as in the case of the sensor 2 (FIG. 11C). That is, the active element built-in module wafer 5A is divided into multiple impositions (each imposition portion is indicated by 1A). These fine through holes 32 are formed, and a conductive material is disposed in these fine through holes 32 to form through electrodes 33.
The fine through holes 32 can be formed by, for example, an ICP-RIE method through a mask pattern. Further, the fine through holes 32 can be formed by a sandblast method, a wet etching method, or a femtosecond laser method. Further, a fine hole is formed at a predetermined depth from one surface of the active element built-in module wafer 5A by one of the methods described above, and then the opposite surface of the active element built-in module wafer 5A is polished. The fine through hole 32 may be formed by exposing the fine hole. The opening diameter of the fine through hole 32 can be set in the range of 1 to 50 μm, preferably 5 to 30 μm.

The through electrode 33 is formed in the fine through hole 32 by, for example, forming a base conductive thin film in the fine through hole 32 by a plasma CVD method or the like, and then depositing a conductive metal by electrolytic field plating. It can be carried out. Thereby, the penetration electrode 33 without a void can be obtained. The through electrode 33 can also be formed by filling the fine through hole 32 with a conductive paste.
Next, a recess for embedding the active element 45 is formed for each imposition 1A, and the active element 45 is embedded in the recess. The concave portion can be formed, for example, by an ICP-RIE method on the exposed active element built-in module wafer 5A by forming a mask pattern on the active element built-in module wafer 5A. It can also be formed by sandblasting, wet etching, or the like. The shape and size of the recess can be appropriately set according to the shape and size of the active element to be embedded. The embedding of the active element 45 is not particularly limited, for example, a method of fixing using an adhesive or a method of fitting the active element in the recess.

Next, the wiring 34 is formed on the surface where the active element 45 is embedded, the wiring 38 is formed on the opposite surface, and insulating layers 37 and 41 such as silicon oxide and silicon nitride are formed on both surfaces. Thereafter, an opening 37a is formed in the insulating layer 37, and the connection bump 6 is formed on the wiring 34 exposed in the opening 37a. In addition, a via 39 is formed in the insulating layer 41, a wiring 40 is formed so as to be connected to the via 39, and a solder bump 46 as an external terminal is formed at a desired location of the wiring 40. As a result, the active element built-in module 5 is manufactured in multiple faces.
Next, the bonding bump 6 is bonded to the terminal 28 of the sensor 2 to bond the multi-sided active element built-in module 5 and the multi-sided sensor 2. Thereby, the sensor unit 1 with multiple impositions is obtained (FIG. 12). Bonding of the sensor 2 and the active element built-in module 5 via the bonding bump 6 can be performed as described above with reference to FIG.
Next, the sensor unit 1 as shown in FIG. 1 is obtained by dicing the multi-sided sensor unit 1.

FIG. 13 is a process diagram showing an embodiment of a method for manufacturing a sensor unit according to the present invention, taking the sensor unit 1 ′ shown in FIG. 5 as an example.
In the present invention, first, the sensor 2 is manufactured by multiple imposition. That is, an SOI (Silicon On Insulator) wafer 11A having a three-layer structure of a silicon layer 12 (active layer silicon), a silicon oxide layer 13, and a silicon layer 14 (substrate silicon) is multi-faced (each facet is indicated by 1A). The sensor 2 is manufactured by multiple imposition by performing desired processing for each imposition 1A (FIG. 13A). The sensor 2 includes a frame member 21, a plurality of through electrodes 27 penetrating the frame member 21, a terminal 28 connected to the through electrode 27, a plurality of beams 22 protruding inward from the frame member 21, A weight 23 supported by the beam 22, a piezoresistive element 16 disposed on the beam 22, a wiring 18 connecting the piezoresistive element 16 and the through electrode 27, and a protective layer 19 covering the wiring 18 have. An opening 19a is formed in the protective layer 19 so that a desired portion of the wiring 18 is exposed. Further, solder bumps 29 as external terminals are formed on the terminals 28. The manufacturing process of the multi-sided sensor 2 will be described later.

  Further, in the method of manufacturing the sensor unit of the present invention, the active element built-in module 5 ′ is manufactured by multi-faceting as in the case of the sensor 2 (FIG. 13B). That is, the active element built-in module wafer 5A is divided into multiple impositions (each imposition portion is indicated by 1A), and an active element 45 is embedded in each subsequent imposition 1A. Thereafter, a wiring 34 is formed on the surface where the active element 45 is embedded, and an insulating layer 37 such as silicon oxide or silicon nitride is further formed. An opening 37a is formed in the insulating layer 37 so that a desired portion of the wiring 34 is exposed, and the connection bump 6 is formed on the wiring 34 exposed in the opening 37a. As a result, the active element built-in module 5 ′ is manufactured with multiple faces. The embedding of the active element 45 in the substrate 31 can be the same as in the above-described embodiment.

Next, the bonding bump 6 is bonded to the wiring 18 of the sensor 2, thereby bonding the multi-sided active element built-in module 5 ′ and the multi-sided sensor 2. As a result, a multi-sided sensor unit 1 ′ is obtained (FIG. 13C). The connection between the wiring 18 of the sensor 2 and the wiring 34 of the active element built-in module 5 'via the bonding bump 6 can be performed as described above with reference to FIG.
Next, the multi-sided sensor unit 1 'is diced to obtain a sensor unit 1' as shown in FIG.

Here, an example of a manufacturing process of the multi-sided sensor 2 will be described with reference to FIGS.
First, an oxidation process is performed on an SOI wafer 11A having a three-layer structure of a silicon layer 12 (active layer silicon), a silicon oxide layer 13, and a silicon layer 14 (substrate silicon), and silicon oxide layers 12a, 12a are formed on both sides of the SOI wafer 11A. 14a is formed, and then silicon nitride layers 12b and 14b are stacked by a plasma CVD method or the like (FIG. 14A).
Next, an opening 15 for forming a resistance element is formed in desired portions of the silicon oxide layer 12a and the silicon nitride layer 12b on the silicon layer 12 (active layer silicon) (FIG. 14B). The opening 15 can be formed, for example, by forming a mask pattern on the silicon nitride layer 12b and performing a sandblast method, a wet etching method, or the like.

Next, the silicon nitride layers 12b and 14b on both sides are removed, and then an impurity such as boron is ion-implanted or thermally diffused into the silicon layer 12 (active layer silicon) exposed in the opening 15 to form P-type or N-type. A diffusion layer is formed to form the piezoresistive element 16 (FIG. 14C).
Next, a silicon oxide layer is further formed on the silicon oxide layer 12a so as to cover the piezoresistive element 16 to form an insulating layer 17, and then the contact holes 17a are formed in the insulating layer 17 so that each piezoresistive element 16 is exposed. (FIG. 14D). The contact hole 17a can be formed, for example, by forming a mask pattern on the insulating layer 17 and using a sandblast method, a wet etching method, or the like.

  Next, the contact hole 17a is filled with a conductive material to form a via, and a wiring 18 is formed on the insulating layer 17 so as to be connected to the via (FIG. 15A). Next, a protective layer 19 is formed so as to cover the wiring 18, and fine through holes 26 are formed in a predetermined plurality of places where the frame member 21 is formed in a later process. A conductive material is provided to form the through electrode 27 (FIG. 15B). The protective layer 19 may be, for example, a silicon nitride layer formed by a plasma CVD method. Further, heat treatment may be performed for the purpose of reducing the contact resistance between the piezoresistive element 16 and the via. When the sensor 2 used for the sensor unit 1 ′ is manufactured, an opening 19a is formed in the protective layer 19 so that a predetermined portion of the wiring 18 is exposed. The opening 19a can be formed, for example, by forming a mask pattern on the protective layer 19 and using a sand blast method, a wet etching method, or the like.

The fine through hole 26 can be formed so as to reach the wiring 18 by the ICP-RIE method from the silicon layer 14 (substrate silicon) side through a mask pattern, for example. Further, the fine through hole 26 can be formed by a sandblast method, a wet etching method, or a femtosecond laser method. The opening diameter of the fine through hole 26 can be set in the range of 1 to 50 μm, preferably 5 to 30 μm.
The through electrode 27 is formed in the fine through hole 26 by, for example, forming a base conductive thin film in the fine through hole 26 by plasma CVD or the like, and then depositing a conductive metal by electrolytic field plating. It can be carried out. Thereby, the penetration electrode 27 without a void can be obtained. The through electrode 26 can also be formed by filling the fine through hole 26 with a conductive paste.

  The formation of the fine through hole 26 and the through electrode 27 may be performed at another stage in the series of processes described. For example, it may be performed before the piezoresistive element 16 is formed on the SOI wafer 11A having a three-layer structure of the silicon layer 12 (active layer silicon), the silicon oxide layer 13, and the silicon layer 14 (substrate silicon), or described later. It may be performed after the frame member 21 is formed.

  Next, a resist pattern for forming the frame member 21, the beam 22 and the weight 23 is formed on the protective layer 19, and desired portions of the protective layer 19 and the insulating layer 17 are removed through the resist pattern. Then, the silicon layer 12 (active layer silicon) is exposed. The protective layer 19 and the insulating layer 17 can be removed by, for example, an ICP-RIE (Inductively Coupled Plasma-Reactive Ion Etching) method, which is a dry etching method using plasma. Next, the exposed silicon layer 12 (active layer silicon) is removed by, for example, a deep RIE method or the like to form a frame member 21, a beam 22, and a weight 23 as shown in FIG. 3 (FIG. 15). (C)). In this state, the space region 24 (four regions 24A, 24B, 24C, and 24D) in FIG. 3 is not yet formed, and the silicon oxide layer 13 is exposed in the space region 24.

  Next, a recess 14 'for forming a gap between the weight 23 and the protective lid member 4 is formed in the silicon layer 14 (substrate silicon) of the SOI wafer 11A (FIG. 15D). Thereafter, through the resist pattern for forming the frame member 21 and the weight 23, the silicon layer 14 (substrate silicon) is removed from the recess 14 'side by, for example, the deep RIE method (FIG. 16A). . In this case, the silicon oxide layer 13 functions as an etching stopper. Next, the exposed silicon oxide layer 13 is removed, and a terminal 28 is formed on the through electrode 27 exposed on the frame member 21 (FIG. 16B). The removal of the silicon oxide layer 13 can be performed, for example, by dry etching using a reactive gas. Thereby, the beam 22 made of the silicon layer 12 (active layer silicon) is formed, and the sensor 2 as shown in FIG. 2 and FIG.

The manufacturing method of the sensor unit of the present invention as described above can perform batch assembly for bonding the sensor and the active element built-in module at the wafer level, can easily manage the process, and can reduce the manufacturing cost. In addition, since bonding is performed using bonding bumps and bonding at low temperatures is possible, it is possible to prevent the influence of heat on the piezoresistive element and to manufacture a highly reliable sensor unit. Become.
In addition, the manufacturing method of the above-mentioned sensor unit is an illustration, and this invention is not limited to these embodiment.

  The present invention can be applied in various fields where a small and highly reliable sensor unit is required.

It is a schematic sectional drawing which shows one Embodiment of the sensor unit of this invention. It is a top view from the silicon layer (substrate silicon) side of the sensor shown in FIG. FIG. 2 is a plan view from the silicon layer (active layer silicon) side of the sensor shown in FIG. 1. It is a partial expanded sectional view for demonstrating an example of joining of the penetration electrode of a sensor and wiring of an active element built-in module via a joint bump. It is a schematic sectional drawing which shows other embodiment of the sensor unit of this invention. FIG. 6 is a partial enlarged cross-sectional view for explaining another example of joining of sensor wiring and active element built-in module wiring via joint bumps in the sensor unit shown in FIG. 5. It is a schematic sectional drawing equivalent to FIG. 1 which shows the sensor which comprises other embodiment of the sensor unit of this invention. FIG. 8 is a plan view from the silicon layer (substrate silicon) side of the sensor shown in FIG. 7 and corresponds to FIG. 2. FIG. 8 is a plan view from the silicon layer (active layer silicon) side of the sensor shown in FIG. 7 and corresponds to FIG. 3. It is a top view equivalent to FIG. 3 which shows the sensor which comprises other embodiment of the sensor unit of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the sensor unit of this invention. It is process drawing which shows one Embodiment of the manufacturing method of the sensor unit of this invention. It is process drawing which shows other embodiment of the manufacturing method of the sensor unit of this invention. It is process drawing which shows the preparation examples of the sensor in the manufacturing method of the sensor unit of this invention. It is process drawing which shows the preparation examples of the sensor in the manufacturing method of the sensor unit of this invention. It is process drawing which shows the preparation examples of the sensor in the manufacturing method of the sensor unit of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 '... Sensor unit 2, 2', 2 "... Sensor 5, 5 '... Active element built-in module 6 ... Joint bump 11 ... SOI substrate 16 ... Piezoresistive element 18 ... Wiring 21 ... Frame member 22 ... Beam 23 ... Weight 27 ... Penetration electrode 28 ... Terminal 34 ... Wiring 45 ... Active element 5A ... Active element built-in module wafer 11A ... SOI wafer

Claims (7)

A sensor using a piezoresistive element, and an active element built-in module joined to the sensor,
The sensor is formed of an SOI substrate having a three-layer structure of silicon layer / silicon oxide layer / silicon layer, and includes a frame member, a plurality of through electrodes penetrating the frame member, and a plurality of protrusions projecting inward from the frame member. A beam, a weight supported by the beam, a piezoresistive element disposed on the beam, and a wiring connecting the piezoresistive element and the through electrode, and between the weights The active element built-in module is joined to the frame member so as to form a predetermined gap,
The module with a built-in active element includes a substrate having a built-in active element and having a plurality of through electrodes in a region outside the active element, and wiring disposed on the substrate so as to be connected to the through electrodes. The wiring is joined to the through electrode of the sensor. A sensor using a piezoresistive element, and an active element built-in module joined to the sensor,
The sensor is formed of an SOI substrate having a three-layer structure of silicon layer / silicon oxide layer / silicon layer, and includes a frame member, a plurality of through electrodes penetrating the frame member, and a plurality of protrusions projecting inward from the frame member. A beam, a weight supported by the beam, a piezoresistive element disposed on the beam, and a wiring connecting the piezoresistive element and the through electrode,
The active element built-in module includes a substrate in which an active element is embedded, and a wiring disposed on the substrate, and the wiring is joined to a wiring of the sensor.   The sensor unit according to claim 1, wherein the through electrode of the sensor and the wiring of the module with a built-in active element are connected via a bonding bump.   The sensor unit according to claim 2, wherein the connection between the wiring of the sensor and the wiring of the module with a built-in active element is via a bonding bump.   The bonding bump is any one of Au, Sn—Au alloy, and Sn—Ag alloy, and any one of Cu / Cr laminated, Cu / Ti laminated, Al / Cr laminated, and Al / Ti laminated so as to sandwich the bonded bump. The sensor unit according to claim 3 or 4, wherein the metal layer is disposed. An SOI wafer having a three-layer structure of silicon layer / silicon oxide layer / silicon layer is partitioned into multiple faces, and a desired processing is performed for each face, and a frame member and a plurality of through electrodes penetrating the frame member A plurality of beams projecting inward from the frame member, a weight supported by the beams, a piezoresistive element disposed on the beam, and a wiring connecting the piezoresistive element and the through electrode And a step of producing a sensor having multiple faces,
The active element built-in module wafer is divided into multiple faces, each face is built with an active element, a plurality of fine through holes are formed in the area outside the active element, and a conductive material is disposed in the fine through holes. Forming a through electrode, forming a wiring connected to the through electrode, and producing an active element built-in module with multiple faces;
The wiring of the module with a built-in active element and the through electrode of the sensor are bonded by a bonding bump so that a predetermined gap is formed between the weight of the sensor and the module with a built-in active element. A process of making a sensor unit;
And a step of dicing the multi-sided sensor unit. An SOI wafer having a three-layer structure of silicon layer / silicon oxide layer / silicon layer is partitioned into multiple faces, and a desired processing is performed for each face, and a frame member and a plurality of through electrodes penetrating the frame member A plurality of beams projecting inward from the frame member, a weight supported by the beams, a piezoresistive element disposed on the beam, and a wiring connecting the piezoresistive element and the through electrode And a step of producing a sensor having multiple faces,
Dividing a wafer for an active element built-in module into multiple impositions, incorporating an active element for each imposition and forming a wiring, and producing an active element built-in module by multiple imposition;
Bonding the wiring of the active element built-in module and the wiring of the sensor by a bonding bump to form a multi-sided sensor unit;
And a step of dicing the multi-sided sensor unit.

Images