JP2009103530A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor device capable of suppressing fluctuation of sensor output caused by an external stress. <P>SOLUTION: In this sensor device, a circuit chip having a piezo resistance element on one surface side is fixed on a base member, and a sensor chip having a movable part on one surface is fixed on the circuit chip. The sensor chip is fixed on the circuit chip through a plurality of bumps arranged so as to enclose the movable part, with the movable part in the facing state to a piezo resistance element forming surface of the circuit chip. The circuit chip is fixed on the base member through the first adhesive member, with the backside of the piezo resistance element forming surface as a facing surface, and the piezo resistance element is formed in a domain enclosed by the bumps on the piezo resistance element forming surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sensor device in which a sensor chip having a movable part on one surface and a circuit chip are fixed to a base member in a state where they are stacked on each other.

Conventionally, as shown in Patent Document 1, for example, there has been proposed a sensor device that is fixed to a base member in a state in which a sensor chip having a movable portion on one surface and a circuit chip are stacked on each other.

In the sensor device disclosed in Patent Document 1, the sensor chip is stacked on the circuit chip via the bumps with the movable part facing the circuit chip. The two chips are electrically connected by bumps, and the movable part is separated from the circuit chip by the bumps.
JP 2006-189418 A

  Incidentally, in the sensor device disclosed in Patent Document 1, a plurality of bumps are arranged so as to surround the movable part. That is, the movable part forming region in the sensor chip is rigid. Therefore, even if an external stress such as an impact is applied to the package as the base member and the stress is applied to the sensor chip via the circuit chip and the bump, the operation of the movable portion, that is, the fluctuation of the sensor output is suppressed.

  However, in the configuration disclosed in Patent Document 1, the circuit chip and the package are also electrically connected via bumps. Therefore, when an external stress is applied to the package, the stress is transmitted to the circuit chip without being attenuated by the bump. In addition, the stress transmitted to the circuit chip is transmitted to the sensor chip via the bumps. Therefore, the stress acting on the sensor chip is increased.

  The circuit chip is formed with a circuit portion for the purpose of amplifying a signal output from the sensor chip, and the element constituting the circuit portion includes a piezoresistive element (for example, a resistance value that changes due to distortion) Diffuse resistance). Therefore, when a stress acts on the circuit chip, the resistance value of the piezoresistive element changes, and as a result, the sensor output may fluctuate.

  An object of this invention is to provide the sensor apparatus which can suppress the fluctuation | variation of the sensor output by an external stress in view of the said problem.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a sensor chip having a movable portion on one surface and a piezoresistive element constituting a circuit portion are formed on one surface side and are electrically connected to the sensor chip. And a base member fixed in a state in which the sensor chip and the circuit chip are stacked on each other, wherein the sensor chip has a movable part on a surface of the circuit chip on which a piezoresistive element is formed. In a state of being opposed to each other, the circuit chip is fixed to the circuit chip through a plurality of bumps arranged so as to surround the movable portion. The circuit chip has a first surface on the base member with the back surface of the piezoresistive element forming surface as an opposing surface. A piezoresistive element is formed in a region fixed by an adhesive member and surrounded by a bump on the piezoresistive element forming surface.

  Thus, according to the present invention, the circuit chip is bonded to the base member via the first bonding member. The circuit chip and the sensor chip are connected by a plurality of bumps, and the plurality of bumps are arranged so as to surround the piezoresistive element in the circuit chip and the movable part in the sensor chip.

  Therefore, even if an external stress such as an impact is applied to the base member, the stress transmitted from the base member to the circuit chip is reduced through the first adhesive member. In addition, since the formation region of the piezoresistive element in the circuit chip is rigid by the bumps, resistance variation of the piezoresistive element due to external stress is suppressed. Furthermore, since the formation area of the movable part in the sensor chip is also rigid by the bumps, the operation of the movable part based on external stress is suppressed. That is, fluctuations in sensor output due to external stress can be suppressed.

  In the first aspect of the present invention, as described in the second aspect, the sensor chip is fixed to the piezoresistive element forming surface of the circuit chip through the second adhesive member having an insulating property together with the plurality of bumps. In addition, the second adhesive member may be separated from the movable part.

  As described above, according to the present invention, the sensor chip is fixed to the piezoresistive element forming surface of the circuit chip through the second adhesive member together with the plurality of bumps. Can be secured. Further, since the second adhesive member is disposed so as to be separated from the movable part, the movable part can operate appropriately.

  In the invention described in claim 2, as described in claim 3, it is preferable that a plurality of bumps are sealed by the second adhesive member. As described above, according to the present invention, since the second adhesive member is disposed around the bump, the strength of the electrical connection portion by the bump can be further improved. Further, the bump can be protected by the second adhesive member.

  In the invention according to claim 2 or claim 3, as described in claim 4, the movable portion located on the inner peripheral side with respect to the second adhesive member is sealed by the second adhesive member. A configuration is good. Thus, according to this invention, since a movable part is sealed by the 2nd adhesion member, the approach of the foreign material to a movable part can be prevented.

  In the invention according to any one of claims 2 to 4, as described in claim 5, an adhesive member having a lower Young's modulus after curing than the second adhesive member is employed as the first adhesive member. Is preferred.

  As described above, according to the present invention, even when an external stress such as an impact is applied to the base member, it is transmitted from the base member to the circuit chip through the first adhesive member that is softer than the second adhesive member. Stress can be effectively reduced. That is, fluctuations in sensor output due to external stress can be effectively suppressed.

  In the invention according to any one of claims 2 to 5, as described in claim 6, as a circuit chip, an analog chip having a piezoresistive element formed on one surface, and a digital electrically connected to the analog chip The analog chip is fixed on the digital chip via the third adhesive member with the back surface of the piezoresistive element forming surface as an opposing surface, and the digital chip is a contact surface with the third adhesive member. It is preferable that the back surface is a facing surface and fixed on the base member via the first adhesive member.

  As described above, according to the present invention, the circuit chip is configured by laminating the analog chip and the digital chip via the third adhesive member. The digital chip and the base member are bonded through the first bonding member. Therefore, even if an external stress such as an impact is applied to the base member, not only the first adhesive member but also the third adhesive member until the stress is transmitted to the analog chip on which the piezoresistive element is formed. The stress is also reduced. That is, the stress itself acting on the analog chip (piezoresistive element) and the sensor chip (movable part) is effectively reduced. Thereby, the fluctuation | variation of the sensor output by external stress can be suppressed.

  In the invention described in claim 6, as described in claim 7, it is preferable that an adhesive member having a lower Young's modulus after curing than the second adhesive member is employed as the third adhesive member.

  As described above, according to the present invention, even when an external stress such as an impact is applied to the base member, it is transmitted from the digital chip to the analog chip through the third adhesive member that is softer than the second adhesive member. Stress can be effectively reduced. That is, fluctuations in sensor output due to external stress can be effectively suppressed.

  In the invention described in claim 1, as described in claim 8, the circuit chip includes an analog chip having a piezoresistive element formed on one surface and a digital chip electrically connected to the analog chip. The analog chip is fixed on the digital chip via the third adhesive member with the back surface of the piezoresistive element forming surface as the opposing surface, and the digital chip is the opposing surface on the back surface of the contact surface with the third adhesive member. As above, it is preferable that the base member is fixed via a first adhesive member.

  Since the operational effect of the present invention is the same as that of the invention described in claim 6, the description thereof is omitted.

  In the invention according to any one of claims 6 to 8, as described in claim 9, the adhesion area with the third adhesion member in the digital chip is larger than the adhesion area with the first adhesion member in the base member. A narrowed configuration may be used.

  Thus, according to the present invention, the bonding area between the digital chip and the analog chip via the third bonding member is smaller than the bonding area between the base member and the digital chip via the first bonding member. ing. Therefore, even if an external stress such as an impact is applied to the base member, the stress transmission area transmitted from the digital chip to the analog chip is small, so that the stress transmitted to the analog chip on which the piezoresistive element is formed is effectively reduced. Can be reduced. Moreover, the stress transmitted to the sensor chip in which the movable part is formed can be effectively reduced. Furthermore, since the adhesion area between the digital chip and the base member is larger than the adhesion area between the analog chip and the digital chip, it is possible to ensure stability during wire bonding between the base member and the circuit chip.

  The invention according to any one of claims 1 to 9, as described in claim 10, has a bottomed cylindrical shape having an opening on one surface and a sensor chip and a circuit chip fixed to the inner surface as a base member. It is good also as a structure which has a case and the cover which obstruct | occludes an opening part in the state in which the sensor chip and the circuit chip were accommodated in the case. As described above, according to the present invention, the sensor chip and the circuit chip are accommodated in the internal space formed by assembling the case and the cover. Therefore, entry of foreign matter into the movable part can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the sensor device according to the first embodiment. FIG. 2 is a plan view showing the positional relationship between the sensor chip and the circuit chip in the sensor device shown in FIG. FIG. 3 is a plan view showing a schematic configuration of the sensor chip. In FIG. 2, a pad 34 and a pad 69 described later are omitted for convenience.

  As shown in FIG. 1, the sensor device 100 includes a base member 10, a circuit chip 30 that is fixed to the base member 10 via a first adhesive member 20, and a first adhesive member 20 in the circuit chip 30. The sensor chip 60 is fixed on the back surface 31b of the adhesive surface 31a via a plurality of bumps 50.

  The base member 10 is a base material on which the circuit chip 30 and the sensor chip 60 are fixed in a stacked state. In the present embodiment, the inner space 13 is formed by a bottomed cylindrical case 11 having an opening on one surface and a cover 12 that closes the opening of the case 11, and the cover 11 is assembled to the case 11. In addition, the circuit chip 30 and the sensor chip 60 are accommodated.

  The case 11 is formed using, for example, ceramic or resin, and a wiring portion (not shown) is formed on the surface or inside thereof. A part of the wiring part is exposed to the internal space 13 and is electrically connected to the pad 34 of the circuit chip 30 via the wire 40, and a part is exposed to the outside of the case 11. Thereby, for example, an output signal from the circuit chip 30 can be transmitted to the outside of the internal space 13 via the wire 40 and the wiring portion. In the present embodiment, ceramic such as alumina is adopted as a constituent material of the case 11, and the case 11 having a wiring portion is configured as a ceramic multilayer wiring board in which ceramic layers are laminated in multiple layers. The circuit chip 30 is fixed to the bottom inner surface 11 a of the bottomed cylindrical case 11 via the first adhesive member 20.

  The cover 12 is made of ceramic, resin, metal, or the like, and is fixed to the case 11 by adhesion, welding, brazing, or the like. By assembling the cover 12, the opening of the case 11 is closed to form a base member 10 (package) having a closed internal space 13. In the present embodiment, the internal space 13 is filled with, for example, nitrogen gas as an inert gas.

  The first adhesive member 20 is for bonding and fixing the base member 10 and the circuit chip 30. The constituent material and form are not particularly limited as long as the circuit chip 30 can be bonded and fixed to the base member 10. Only an organic component may be used, or an organic component mixed with an inorganic component or a metal component (for example, a silver paste) may be used. In the present embodiment, as the first adhesive member 20, a soft adhesive member (for example, a silicon-based adhesive member) having a Young's modulus (for example, about several MPa) that is deformed by receiving pressure in a cured state is employed. is doing.

  The circuit chip 30 is obtained by forming a processing circuit (not shown) of the sensor chip 60 including a switching element such as a MOS transistor, a resistor, a capacitor, and the like on a semiconductor substrate 31 such as a silicon substrate. In the present embodiment, this processing circuit is configured to perform predetermined processing (for example, CV conversion or amplification) on the detection signal of the sensor chip 60.

  A plurality of bump pads 32 connected to the sensor chip 60 via the bumps 50 are formed on the back surface 31b of the bonding surface 31a with the first bonding member 20 in the semiconductor substrate 31 (circuit chip 30). The bump pad 32 is made of aluminum, for example. In addition, on the back surface 31b side of the semiconductor substrate 31, a plurality of piezoresistive elements (for example, diffused resistors) whose resistance values change under the influence of the distortion of the semiconductor substrate 31 are integrated as a part of the processing circuit. Is formed. A plurality of bump pads 32 are formed so as to surround the piezoresistive element forming region 33 (so as to form an intermittent ring) on the back surface 31b of the semiconductor substrate 31 (hereinafter referred to as a piezoresistive element forming surface 31b). Is formed.

  In the present embodiment, as shown in FIG. 2, in a planar rectangular semiconductor substrate 31, a part of a substantially planar rectangular shape including the center 70 (region surrounded by a broken line in FIG. 2) is formed as a piezoresistive element. This is a region 33. Four bump pads 32 are formed on the outer peripheral side of the piezoresistive element forming region 33 so as to be point-symmetric with respect to the center 70 of the semiconductor substrate 31. More specifically, four bump pads 32 are formed corresponding to each corner of the piezoresistive element forming region 33 having a substantially planar rectangular shape. In the present embodiment, as shown in FIG. 2, among the four bump pads 32, the three bump pads 32a electrically and mechanically connect the circuit chip 30 and the sensor chip 60. The remaining one bump pad 32b is a dummy pad that mechanically connects the circuit chip 30 and the sensor chip 60 without providing an electrical connection function.

  1 and 2, the planar substantially rectangular circuit chip 30 is larger than the planar substantially rectangular sensor chip 60, and the outer peripheral edge of the sensor chip 60 is larger than the outer peripheral edge of the circuit chip 30. It is inside. A pad 34 is formed on the outer peripheral side of the bump pad 32 on the piezoresistive element forming surface 31 b of the semiconductor substrate 31. The pad 34 is electrically connected to a wiring portion formed on the case 11 via a wire 40. On the piezoresistive element forming surface 31b of the circuit chip 30 (semiconductor substrate 31) configured as described above, the sensor chip 60 is stacked via the bumps 50.

  The bump 50 fixes the circuit chip 30 and the sensor chip 60. The bump 50 may be formed by various methods such as a general stud bump forming method, a solder bump forming method, screen printing using a conductive paste such as gold, or printing by an inkjet method using a nano paste such as gold. It can be formed using a method. In the present embodiment, among the four bumps 50 corresponding to the bump pad 32, as shown in FIG. 2, three bumps 50a are connected to the bump pad 32a, and the remaining one bump 50b is It is connected to the bump pad 32b.

  The sensor chip 60 has a movable portion 62 formed on one surface 61a (hereinafter, referred to as a movable portion forming surface 61a) of a semiconductor substrate 61 such as an SOI (Silicon On Insulator) substrate. In the present embodiment, a beam structure having a comb-tooth structure is formed by performing known micromachining on the semiconductor substrate 61, and a part of the beam structure becomes a movable portion 62 that is movable by application of acceleration. Yes. That is, as the sensor chip 60, an acceleration sensor chip that detects acceleration based on a change in capacitance accompanying the movement (displacement) of the movable portion 62 is configured.

  Specifically, as shown in FIG. 3, the semiconductor substrate 61 is etched to form a trench 63, whereby a weight portion 64 that can be displaced in the direction of application of acceleration (the direction of the white arrow in FIG. 3) The movable part 65 is connected to the weight part 64 and is composed of a movable electrode 65 that is displaced together with the weight part 64, a beam part 66 that can be spring-deformed to displace the weight part 64, and the movable electrode 65. A fixed electrode 67 and the like are formed. Note that a region 68 surrounded by a broken line shown in FIG. 3 is a semiconductor substrate 61 (on the lower surface side of the beam structure) in order to make the movable portion 62 movable among the beam structures partitioned by the trench 63. For example, in the SOI substrate, a region where an oxide film) is removed is shown.

  In the sensor chip 60 having such a configuration, when the acceleration including the component in the direction of the white arrow shown in FIG. 3 is received, the movable portion 62 is displaced in the direction of the white arrow by the spring function of the beam portion 66. Then, according to the displacement of the movable electrode 65 at this time, the distance between the movable electrode 65 and the fixed electrode 67 changes, and the capacitance between both the electrodes 65 and 67 changes. The acceleration is detected based on the change in capacitance. Such a configuration is well known as disclosed in, for example, Japanese Patent Application Laid-Open No. 2006-153482, and a detailed description thereof will be omitted.

  In addition, on the movable part forming surface 61 a of the semiconductor substrate 61 and on the outer peripheral side of the movable part 62 formation region, the pads 69 connected to the bumps 50 correspond to the bump pads 32 and correspond to the movable parts 62. It is formed so as to surround the region where the film is formed (so as to form an intermittent ring). In the present embodiment, among the four pads 69 corresponding to the four bumps 50, as shown in FIG. 3, three pads 69a are pads connected to the bumps 50a, and the remaining one pad 69b. Is a pad connected to the bump 50b. That is, the connection part of the pad 69a, the bump 50a, and the bump pad 32a electrically and mechanically connects the sensor chip 60 and the circuit chip 30, and the pad 69a, the bump 50b, and the bump pad 32b. The connection part mechanically connects the sensor chip 60 and the circuit chip 30.

  In the sensor device 100 configured as described above, the circuit chip 30 is fixed to the bottom inner surface 11 a of the case 11 via the first adhesive member 20. Thereby, even if an external stress such as an impact is applied to the base member 10 including the case 11 and the cover 12, the stress transmitted from the case 11 to the circuit chip 30 can be reduced by the first adhesive member 20. it can. In particular, in the present embodiment, since a soft adhesive member is employed as the first adhesive member 20, the stress transmitted from the case 11 to the circuit chip 30 can be effectively reduced.

  In the present embodiment, the bump 50 (the connection portion between the bump pad 32 and the pad 69 via the bump 50) is formed in the piezoresistive element forming region 33 in the circuit chip 30 and the movable portion 62 in the sensor chip 60. Is formed so as to surround the region 62a (region surrounded by a broken line shown in FIG. 2). As a result, the piezoresistive element forming region 33 in the circuit chip 30 inside the bump 50 (connection portion) and the movable portion forming region 62a in the sensor chip 60 are rigid. That is, even if stress is transmitted to the circuit chip 30, distortion is less likely to occur in the piezoresistive element forming region 33 in the circuit chip 30. Further, even if stress is transmitted to the sensor chip 60 via the bumps 50, the movable portion forming region 62a in the sensor chip 60 is less likely to be distorted. Due to the above effects, according to the present embodiment, it is possible to suppress the resistance fluctuation of the piezoresistive element based on the external stress and the displacement of the movable portion 62, and consequently the fluctuation of the sensor output.

  In the present embodiment, the base member 10 includes a bottomed cylindrical case 11 having an opening and a cover 12, and a sensor is provided in a closed internal space 13 formed by assembling the cover 12 to the case 11. A chip 60 and a circuit chip 30 are accommodated. Accordingly, it is possible to suppress the entry of foreign matter from the outside into the internal space 13, and consequently to suppress the biting of foreign matter into the movable portion 62. Moreover, since the movable part 62 is made to oppose the circuit chip 30, it can suppress the biting of the foreign material to the movable part 62 also by this.

  Further, in the present embodiment, the stress transmitted to the bump 50 that connects the circuit chip 30 and the sensor chip 60 is reduced through the first adhesive member 20. Further, a wire 40 is employed as a connection portion between the circuit chip 30 and the wiring portion of the case 11. The wire 40 itself can relieve stress. That is, it is possible to ensure connection reliability at each connection portion of the sensor chip 60 and the circuit chip 30 and between the circuit chip 30 and the wiring portion of the case 11.

  In the present embodiment, four bump pads 32 are point-symmetrical with respect to the center 70 of the semiconductor substrate 31 and are formed at the corners of the planar rectangular piezoresistive element forming region 33, respectively. showed that. However, as shown in FIG. 4, for example, four bump pads 32 may be formed corresponding to each side (for example, the center of each side) of the planar rectangular piezoresistive element forming region 33. . FIG. 4 is a plan view showing a modification. Further, it does not have to be point-symmetric with respect to the center 70. What is necessary is just to form intermittently cyclic | annular form so that the piezoresistive element formation area | region 33 may be surrounded at least. In other words, it is only necessary that the piezoresistive element formation region 33 is included in a region 71 (region surrounded by a two-dot chain line in FIG. 4) connecting the adjacent bump pads 32. For example, if the piezoresistive element forming region 33 is a planar polygonal shape, the bump pads 32 may be formed corresponding to at least each corner or each side. However, the shorter the distance between the adjacent bump pads 32, the more rigid the piezoresistive element formation region 33 of the circuit chip 30 surrounded by the bump pads 32 (connection portion). Note that the relationship between the pad 69 corresponding to the bump pad 32 and the movable portion forming region 62a may satisfy the same relationship as the relationship between the bump pad 32 and the piezoresistive element forming region 33 described above.

  In the present embodiment, the first adhesive member 20 is a soft adhesive member (for example, a silicon-based adhesive member) having a Young's modulus (for example, about several MPa) that is deformed by receiving pressure in the cured state. An example of adopting is shown. However, as the first adhesive member 20, an adhesive member having a Young's modulus that hardly undergoes deformation under pressure after being cured may be employed. Even when such an adhesive member is used, the stress can be reduced by the first adhesive member 20.

Further, in the present embodiment, an example is shown in which one of the four connection portions including the bump pad 32, the bump 50, and the pad 69 is a connection portion that does not provide an electrical connection function. However, if it is possible to surround the piezoresistive element formation region 33 and the movable portion formation region 62a with only a connection portion that provides an electrical connection function, a connection portion that does not provide an electrical connection function is unnecessary. can do. In other words, the connection portion can be configured by only the bump pad 32a, the bump 50a, and the pad 69a.
(Second Embodiment)
Next, 2nd Embodiment of this invention is described based on FIG.5 and FIG.6. FIG. 5 is a cross-sectional view showing a schematic configuration of the sensor device according to the second embodiment, and corresponds to FIG. 1 shown in the first embodiment. FIG. 6 is a plan view showing a positional relationship between the sensor chip and the circuit chip in the sensor device shown in FIG. 5, and corresponds to FIG. 2 shown in the first embodiment. In FIG. 6, a pad 34, a pad 39, and a pad 69, which will be described later, are omitted for convenience.

  Since the sensor device 100 according to the second embodiment is often in common with that according to the first embodiment, a detailed description of the common parts will be omitted below, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, an example in which the circuit chip 30 is one chip has been described. On the other hand, in the present embodiment, the circuit chip 30 has two chips, a digital chip 35 and an analog chip 36. And, between the base member 10 and the sensor chip 60, two chips 35 and 36 are laminated so that the digital chip 35 is formed on the base member 10 side and the analog chip 36 is formed on the sensor chip 60 side. To do.

  The digital chip 35 is obtained by forming a digital circuit portion of a processing circuit of the sensor chip 60 on a semiconductor substrate 37 such as a silicon substrate. The semiconductor substrate 37 (digital chip 35) is bonded and fixed to the bottom inner surface 11a of the case 11 via the first bonding member 20. A third adhesive member 21 that fixes the digital chip 35 and the analog chip 36 in a stacked state is disposed on the back surface 37 b side of the adhesive surface 37 a with the first adhesive member 20 in the semiconductor substrate 37. As shown in FIG. 6, the digital chip 35 having a substantially rectangular plane is larger than the analog chip 36 having a substantially rectangular plane, and the outer peripheral end of the analog chip 36 is inside the outer peripheral end of the digital chip 35. ing. A pad 34 is formed on the outer peripheral side of the back surface 37 b of the semiconductor substrate 37 with respect to the bonding portion with the third bonding member 21. As shown in the first embodiment, the pad 34 is electrically connected to the wiring portion formed in the case 11 via the wire 40. Further, on the back surface 37 b of the semiconductor substrate 37, on the outer peripheral side of the bonding portion with the third bonding member 21, a pad (for electrically connecting the analog chip 36 and the digital chip 35 through the wire 41 ( (Not shown) is also formed.

  The third adhesive member 21 is for bonding and fixing the digital chip 35 and the analog chip 36. The constituent material and form are not particularly limited as long as the digital chip 35 can be bonded and fixed to the analog chip 36. Only an organic component may be used, or an organic component mixed with an inorganic component or a metal component (for example, a silver paste) may be used. In the present embodiment, the third adhesive member 21 is the same adhesive member as the first adhesive member 20 (soft modulus having a Young's modulus (for example, about several MPa) that is deformed by receiving pressure in the cured state) Adhesive member) is adopted.

  In the analog chip 36, the analog circuit portion of the processing circuit of the sensor chip 60 is formed on a semiconductor substrate 38 such as a silicon substrate, and a piezoresistive element is included as an element constituting the analog circuit. A plurality of bump pads 32 connected to the sensor chip 60 via the bumps 50 are formed on the back surface 38 b of the bonding surface 38 a with the third bonding member 21 in the semiconductor substrate 38. A plurality of piezoresistive elements (for example, diffused resistors) whose resistance values change under the influence of the distortion of the semiconductor substrate 38 are collectively formed on the back surface 38 b side of the semiconductor substrate 38. A plurality of bump pads 32 are formed so as to surround the piezoresistive element formation region 33 (so as to form an intermittent ring) on the back surface 38b (hereinafter, referred to as a piezoresistive element formation surface 38b) of the semiconductor substrate 38. Is formed.

  In the present embodiment, as shown in FIG. 6, in the planar rectangular semiconductor substrate 38, a substantially planar rectangular partial region including the center 72 is a piezoresistive element forming region 33. Then, four bump pads 32 (32a, 32b) are formed in the same manner as in the first embodiment so as to be point-symmetric with respect to the center 72 of the semiconductor substrate 38 on the outer peripheral side of the piezoresistive element forming region 33. Yes.

  As shown in FIGS. 5 and 6, the planar substantially rectangular analog chip 36 is larger than the planar substantially rectangular sensor chip 60, and the outer peripheral end of the sensor chip 60 is larger than the outer peripheral end of the analog chip 36. It is inside. A pad 39 is formed on the outer peripheral side of the bump pad 32 on the piezoresistive element forming surface 38 b of the semiconductor substrate 38. The pad 39 is connected to a pad (not shown) formed on the semiconductor substrate 37 via the wire 41.

  On the piezoresistive element forming surface 38b of the circuit chip 30 (semiconductor substrate 31) configured as described above, the sensor chip 60 is stacked via the bumps 50. The bump 50 and the sensor chip 60 are the same as those in the first embodiment.

  As described above, in the sensor device 100 according to the present embodiment, the semiconductor substrate 37 (digital chip 35) is fixed to the bottom inner surface 11a of the case 11 via the first adhesive member 20, and the third adhesive member 21 is interposed therebetween. An analog chip 36 is fixed on the digital chip 35. Thereby, even if an external stress such as an impact is applied to the base member 10 including the case 11 and the cover 12, the stress transmitted from the case 11 to the digital chip 35 can be reduced by the first adhesive member 20. it can. Furthermore, the stress transmitted from the digital chip 35 to the analog chip 36 can be reduced by the third adhesive member 21. That is, the stress transmitted from the base member 10 to the analog chip 36 on which the piezoresistive element is formed can be effectively reduced by passing through the first adhesive member 20 and the third adhesive member 21. . In the present embodiment, soft adhesive members are employed as the first adhesive member 20 and the third adhesive member 21. Therefore, the stress transmitted from the case 11 to the analog chip 36 via the digital chip 35 can be reduced more effectively.

  Further, in the present embodiment, as in the first embodiment, the bump 50 is a region 62a in which the movable portion 62 is formed in the piezoresistive element formation region 33 in the analog chip 36 and the sensor chip 60 (broken line shown in FIG. 6). (Region surrounded by). As a result, the piezoresistive element formation region 33 in the analog chip 36 inside the bump 50 (connection portion) and the movable portion formation region 62a in the sensor chip 60 are rigid. That is, even if stress is transmitted to the analog chip 36, distortion is less likely to occur in the piezoresistive element forming region 33 in the analog chip 36. Further, even if stress is transmitted to the sensor chip 60 via the bumps 50, the movable portion forming region 62a in the sensor chip 60 is less likely to be distorted. Due to the above effects, according to the present embodiment, the resistance variation of the piezoresistive element based on the external stress and the displacement of the movable portion 62 are more effectively suppressed compared to the first embodiment, and the variation of the sensor output is consequently reduced. It can suppress more effectively compared with 1st Embodiment.

  In the present embodiment, among the processing circuits of the sensor chip 60, the digital circuit portion is formed on the semiconductor substrate 37 as the digital chip 35, and the analog circuit portion is formed on the semiconductor substrate 38 as the analog chip 36. Thereby, the size of the circuit chip 30 in the direction perpendicular to the stacking direction of the circuit chip 30 and the sensor chip 60 is smaller than that of the configuration of the first embodiment in which the processing circuit is integrated on the semiconductor substrate 31. That is, the transmission range of stress from the base member 10 (case 11) via the first adhesive member 20 is narrower than that of the first embodiment. Further, the bonding area between the digital chip 35 and the analog chip 36 via the third bonding member 21 is narrower than the bonding area between the case 11 and the digital chip 35 via the first bonding member 20. . That is, the stress transmission range between the digital chip 35 and the analog chip 36 is further narrowed. Therefore, the stress transmitted to the analog chip 36 in which the piezoresistive element is formed can be effectively reduced by these effects. Further, the stress transmitted to the sensor chip 60 connected to the analog chip 36 via the bump 50 can be effectively reduced. Furthermore, since the bonding area between the digital chip 35 and the case 11 is larger than the bonding area between the analog chip 36 and the digital chip 35, it is possible to ensure stability during wire bonding between the case 11 and the digital chip 35. it can.

  In the present embodiment, of the digital chip 35 and the analog chip 36 as the circuit chip 30, the digital chip 35 is bonded to the base member 10 (case 11) side. Therefore, it is possible to suppress the malfunction of the movable part 62 due to the clock signal or the like.

  In the present embodiment, the stress transmitted to the bumps 50 connecting the analog chip 36 and the sensor chip 60 is reduced through the first adhesive member 20 and the third adhesive member 21. Further, wires 40 and 41 are employed as a connection between the digital chip 35 and the wiring part of the case 11 and a connection part between the analog chip 36 and the digital chip 35, respectively. The wires 40 and 41 themselves can relieve stress. That is, it is possible to ensure connection reliability at each connection portion of the sensor chip 60 and the analog chip 36, the analog chip 36 and the digital chip 35, and the digital chip 35 and the wiring portion of the case 11.

In the present embodiment, an example in which the same adhesive member as the first adhesive member 20 is employed as the third adhesive member 21 has been described. However, an adhesive member different from the first adhesive member 20 may be adopted as the third adhesive member 21.
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view illustrating a schematic configuration of the sensor device according to the third embodiment.

  Since the sensor device according to the third embodiment is often in common with those according to the above-described embodiments, detailed description of the common parts will be omitted, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown to each embodiment mentioned above.

  For example, in the second embodiment, an example is shown in which the sensor chip 60 is fixed to the analog chip 36 constituting the circuit chip 30 via the bumps 50. On the other hand, in the present embodiment, as shown in FIG. 7, the sensor chip 60 is disposed not only via the bump 50 but also through the second adhesive member 22 arranged so as not to hinder the movement of the movable portion 62. Is fixed to the analog chip 36 constituting the circuit chip 30 as a first feature. The second feature is that at least one of the first adhesive member 20 and the third adhesive member 21 has a lower Young's modulus after curing (softer) than the second adhesive member 22.

  The second adhesive member 22 mechanically connects the sensor chip 60 and the circuit chip 30 (analog chip 36) together with the bumps 50. The constituent material and form are not particularly limited as long as the sensor chip 60 can be bonded and fixed to the circuit chip 30 (analog chip 36). In the present embodiment, as the second adhesive member 22, as shown in FIG. 7, a film-like adhesive member having a recess formed on the sensor chip 60 side so as not to hinder the movement of the movable portion 62 is employed. ing. Such a second adhesive member 22 is described in, for example, Japanese Patent Application Laid-Open No. 2006-189418 by the present applicant, and thus a detailed description thereof is omitted.

  Further, in the present embodiment, as shown in FIG. 7, the second adhesive member 22 is disposed around the plurality of bumps 50, and the bump 50 (the bump pad 32 and the pad 69 via the bump 50 are arranged). The connection portion is sealed by the second adhesive member 22. Further, the second adhesive member 22 is annularly disposed on the piezoresistive element forming surface 38b of the semiconductor substrate 38 (on the movable portion forming surface 61a of the semiconductor substrate 61) so as to surround the movable portion 62, and the second adhesive member 22 The movable part 62 is sealed by the adhesive member 22. A pad 39 is formed on the outer peripheral side of the piezoresistive element forming surface 38 b of the semiconductor substrate 38 with respect to the arrangement site of the second adhesive member 22.

  In the present embodiment, the first adhesive member 20 and the third adhesive member 21 are made of the same adhesive member, and the adhesive member has a lower Young's modulus after curing than the second adhesive member 22. The material is adopted. Specifically, as the first adhesive member 20 and the third adhesive member 21, a soft adhesive member having a Young's modulus that is deformed by receiving pressure in the cured state is adopted, and the second adhesive member 22 is used. As an adhesive member, the adhesive member has a Young's modulus that hardly deforms when subjected to pressure in a cured state.

  Thus, according to the sensor device 100 according to the present embodiment, the sensor chip 60 is fixed to the circuit chip 30 (analog chip 36) via the bump 50 and the second adhesive member 22. Therefore, in the connection between the sensor chip 60 and the circuit chip 30, higher mechanical strength than that of the above-described embodiment can be ensured. In particular, in the present embodiment, since the second adhesive member 22 is disposed around the bump 50, the connection reliability of the connection portion via the bump 50 can be improved. Further, the bumps 50 can be protected from corrosion by the second adhesive member 22. Furthermore, since the movable part 62 is sealed by the second adhesive member 22 arranged in an annular shape, it is possible to suppress biting of foreign matter into the movable part 62.

  In the present embodiment, the second adhesive member 22 is annularly disposed so as to surround the movable portion 62 while covering the periphery of the bump 50. Thereby, even if stress is transmitted to the analog chip 36, distortion is less likely to occur in the piezoresistive element forming region 33 in the analog chip 36 than in the above-described embodiment.

  Further, as the first adhesive member 20 and the third adhesive member 21, adhesive members having a lower Young's modulus after curing than the second adhesive member 22 are employed. That is, the stress transmitted from the base member 10 (case 11) to the analog chip 36 on which the piezoresistive element is formed can be more effectively reduced. That is, in the sensor device 100 according to the present embodiment, due to these effects, it is possible to suppress the resistance fluctuation of the piezoresistive element and the displacement of the movable part 62 based on the external stress, and consequently the fluctuation of the sensor output.

  In the present embodiment, an example in which an adhesive member having a lower Young's modulus after curing than the second adhesive member 22 is adopted as the first adhesive member 20 and the third adhesive member 21 is shown. However, as the first adhesive member 20 and the third adhesive member 21, an adhesive member having a higher Young's modulus after curing than the second adhesive member 22 or an adhesive member having the same Young's modulus may be employed. From the viewpoint of stress reduction, at least one of the first adhesive member 20 and the third adhesive member 21 (more preferably both adhesive members 20, 21) has a Young's modulus after curing as compared with the second adhesive member 22. A low adhesive member may be employed.

  In the present embodiment, the example in which the bumps 50 are sealed and the movable portion 62 is sealed by the second adhesive member 22 has been described. However, the movable portion 62 may not be sealed by the second adhesive member 22, or the bump 50 may not be sealed. Further, the second adhesive member 22 is not limited to a film-like adhesive member having a recess.

  Moreover, in this embodiment, the example which applies the 2nd adhesion member 22 with respect to the structure shown in 2nd Embodiment was shown. However, you may apply the 2nd adhesive member 22 with respect to the structure shown in 1st Embodiment, and the modification of each embodiment. In the case where the circuit chip 30 is constituted by one chip as shown in the first embodiment, an adhesive member having a lower Young's modulus after curing than the second adhesive member 22 is used as the first adhesive member 20. Adopt it.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example in which the base member 10 includes a case 11 and a cover 12 is shown. However, the base member 10 is not particularly limited as long as the circuit chip 30 and the sensor chip 60 are fixed in a stacked state. For example, only the case 11 may be employed, or a flat base member 10 may be employed.

  In the present embodiment, an example of an acceleration sensor chip is shown as the sensor chip 60. However, as the sensor chip 60, any sensor chip in which a movable part that is displaced by a mechanical amount is formed on one surface side can be adopted. For example, in addition to the above, a known angular velocity sensor chip can be employed.

It is sectional drawing which shows schematic structure of the sensor apparatus which concerns on 1st Embodiment. FIG. 2 is a plan view showing a positional relationship between a sensor chip and a circuit chip in the sensor device shown in FIG. 1. It is a top view which shows schematic structure of a sensor chip. It is a top view which shows the modification of arrangement | positioning of the pad for bumps. It is sectional drawing which shows schematic structure of the sensor apparatus which concerns on 2nd Embodiment. FIG. 6 is a plan view showing a positional relationship between a sensor chip and a circuit chip in the sensor device shown in FIG. 5. It is sectional drawing which shows schematic structure of the sensor apparatus which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Base member 20 ... 1st adhesive member 21 ... 3rd adhesive member 22 ... 2nd adhesive member 30 ... Circuit chip 33 ... Piezoresistive element formation area 35. .... Digital chip 36 ... Analog chip 50 ... Bump 60 ... Sensor chip 62 ... Movable part 100 ... Sensor device

Claims (10)

A sensor chip having a movable part on one surface;
A circuit chip in which a piezoresistive element constituting a circuit unit is formed on one surface side and electrically connected to the sensor chip;
A base member fixed in a state where the sensor chip and the circuit chip are stacked on each other,
The sensor chip is fixed to the circuit chip via a plurality of bumps arranged so as to surround the movable part in a state where the movable part is opposed to a piezoresistive element forming surface of the circuit chip.
The circuit chip is fixed to the base member via a first adhesive member with the back surface of the piezoresistive element forming surface as an opposing surface, and in a region surrounded by the bumps on the piezoresistive element forming surface, A sensor device, wherein the piezoresistive element is formed. The sensor chip, together with the plurality of bumps, is fixed to the piezoresistive element forming surface of the circuit chip via a second adhesive member having insulation,
The sensor device according to claim 1, wherein the second adhesive member is separated from the movable portion.   The sensor device according to claim 2, wherein the plurality of bumps are sealed by the second adhesive member.   The said movable part which is sealed cyclically | annularly by the said 2nd adhesion member and is located in the inner peripheral side rather than the said 2nd adhesion member is sealed, The Claim 2 or Claim 3 characterized by the above-mentioned. Sensor device.   5. The sensor device according to claim 2, wherein the first adhesive member has a lower Young's modulus after curing than the second adhesive member. The circuit chip includes an analog chip in which the piezoresistive element is formed on one surface, and a digital chip electrically connected to the analog chip,
The analog chip is fixed on the digital chip via the third adhesive member with the back surface of the piezoresistive element forming surface as an opposing surface,
6. The digital chip is fixed on the base member via the first adhesive member with the back surface of the contact surface with the third adhesive member as an opposing surface. The sensor device according to claim 1.   The sensor device according to claim 6, wherein the third adhesive member has a lower Young's modulus after curing than the second adhesive member. The circuit chip includes an analog chip in which the piezoresistive element is formed on one surface, and a digital chip electrically connected to the analog chip,
The analog chip is fixed on the digital chip via a third adhesive member with the back surface of the piezoresistive element forming surface as a facing surface,
The digital chip is fixed on the base member via the first adhesive member with the back surface of the contact surface with the third adhesive member as an opposing surface. Sensor device.   The adhesion area with the said 3rd adhesion member in the said digital chip is narrower than the adhesion area with the said 1st adhesion member in the said base member, The any one of Claims 6-8 characterized by the above-mentioned. Sensor device.   As the base member, a bottomed cylindrical case having an opening on one surface and the sensor chip and the circuit chip being fixed on the inner surface, and the sensor chip and the circuit chip are accommodated in the case The sensor device according to claim 1, further comprising: a cover that closes the opening.

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