JP2008209163A - Sensor apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor apparatus capable of suppressing the effect of disturbances such as electric noise and temperature and achieving high accuracy. <P>SOLUTION: A circuit part Dc for processing output signals of a sensor chip 1 is formed on the side opposite to the sensor chip 1 in a first packaging substrate 2. Through-hole wirings 24 to be electrically connected to the sensor chip 1 and the circuit part Dc are formed in the first packaging substrate 2. In the sensor chip 1 and the first packaging substrate 2, a bump 9 formed in the surface of one pad 29 among pads 19 and 29 formed in the opposite surfaces of the sensor chip 1 and the first packaging substrate 2 is joined to the other pad 19 by normal-temperature bump bonding. The circuit part Dc includes a temperature detection part and a temperature compensation circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sensor device.

  Conventionally, a circuit unit including an acceleration sensor chip formed using a semiconductor substrate and having four piezoresistive bridge circuits and a temperature compensation circuit for correcting an output signal of the acceleration sensor chip according to the ambient temperature has been formed. A sensor device including an IC chip has been proposed (see, for example, Patent Documents 1 and 2).

  Here, in the sensor device disclosed in Patent Document 1, since the acceleration sensor chip and the IC chip are housed in one package, and the acceleration sensor chip and the IC chip are separate, the acceleration sensor chip and the IC chip. The wiring length to the circuit part of the IC is increased and affected by electrical noise, or the temperature difference between the temperature of the piezoresistor formed on the acceleration sensor chip and the temperature of the temperature detection part formed on the IC chip There was a concern that it would be affected by temperature.

  On the other hand, Patent Document 2 discloses a sensor chip made of an acceleration sensor chip, a first package substrate made of an IC chip, and a second package chip made of a recess in which a sensor chip is housed. And a sensor chip is flip-chip mounted on one surface side of the first package substrate, and a second package substrate surrounds the sensor chip on the one surface side of the first package substrate. A sensor device sealed in the form is disclosed.

Conventionally, a technique for defining a displacement amount allowed for a movable portion of an acceleration sensor chip by a protruding size of a solder bump has been described (for example, see Patent Document 3).
JP 2004-69619 A JP 2005-127750 A Microfilm of Japanese Utility Model No. 63-89584 (Japanese Utility Model Laid-Open No. 2-1663)

  Incidentally, in the sensor device disclosed in Patent Document 2, the sensor chip is flip-chip mounted on the first package substrate. In the flip-chip mounting process, the sensor chip pad and the IC chip are formed of an acceleration sensor chip. If a bonding method is employed in which solder bumps are interposed between the pads of the first package substrate, the solder bumps need to be heated to a temperature of, for example, about 300 ° C. so that the solder bumps melt during flip chip mounting. In addition, a thermal load is applied to the circuit portion of the sensor chip and the first package substrate, and the output accuracy may be reduced. That is, when the technique described in Patent Document 3 is applied to the sensor device disclosed in Patent Document 2, a thermal load is applied to the sensor chip and the circuit unit, and output accuracy is reduced. There is a fear.

  Further, in the case where the protrusion amount of the solder bump defines the amount of displacement allowed for the movable part of the sensor chip made of the acceleration sensor chip, a load is applied during flip-chip mounting and the first and second movable parts of the sensor chip are applied. Although it is conceivable to control the distance from the package substrate, the distance varies due to variations in the heating temperature during flip-chip mounting, and reliability decreases.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a sensor device that can suppress the influence of disturbances such as electric noise and temperature and can be highly accurate.

  The invention according to claim 1 is a first package substrate in which a sensor chip formed using a first semiconductor substrate and a sensor chip formed using a second semiconductor substrate are flip-chip mounted on one surface side. And a second package substrate that is formed using a third semiconductor substrate and is sealed to surround the sensor chip on the one surface side of the first package substrate, and outputs an output signal of the sensor chip. A circuit portion for signal processing is formed on the surface facing the sensor chip in the first package substrate, and the through-hole wiring electrically connected to the sensor chip and the circuit portion on the first package substrate And the sensor chip and the first package substrate are formed such that the bump formed on the surface of one of the pads formed on the respective opposing surfaces and the other pad are at room temperature. They are joined by amplifier bonding, characterized by comprising.

  According to the present invention, the sensor chip is housed in an airtight space surrounded by the first package substrate and the second package substrate, and the circuit portion for processing the output signal of the sensor chip is formed in the sensor chip. Therefore, it is possible to suppress the influence of disturbances such as electrical noise and temperature, and to achieve high accuracy, and the sensor chip and the first package substrate are pads formed on the opposing surfaces of each other. Since the bump formed on the surface of one of the pads and the other pad are bonded by room temperature bump bonding, the sensor chip and the first package are mounted when the sensor chip is flip-chip mounted on the first package substrate. Since no thermal load is applied to the circuit portion of the substrate, the output can be highly accurate.

  According to a second aspect of the present invention, in the first aspect of the invention, the sensor chip is an acceleration sensor chip in which a movable portion is provided with a piezoresistor, and the circuit unit includes a temperature detection unit that detects an ambient temperature and the circuit unit. A temperature compensation circuit for correcting the output signal of the sensor chip based on the output of the temperature detection unit is included.

  According to the present invention, the circuit unit includes the temperature compensation circuit that corrects the output signal of the acceleration sensor chip in which the movable unit is provided with the piezoresistor based on the output of the temperature detection unit. Can be suppressed and high accuracy can be achieved.

  According to a third aspect of the present invention, in the second aspect of the present invention, the protruding dimension of the bump is such that the distance between the first package substrate and the movable portion defines a displacement amount allowed for the movable portion. It is characterized by being set.

  According to the present invention, when the sensor chip is flip-chip mounted on the first package substrate, the distance between the movable part and the first package substrate is accurately determined by the load applied to the bump at room temperature. It is possible to control well, and the variation in the amount of displacement allowed for the movable part can be reduced for each product. As a result, reliability can be improved.

  According to the first aspect of the present invention, there is an effect that the influence of disturbance such as electric noise and temperature can be suppressed and high accuracy can be achieved.

  Hereinafter, the sensor device of the present embodiment will be described with reference to FIGS.

  The sensor device of the present embodiment is an acceleration sensor device, and includes a sensor chip 1 composed of an acceleration sensor chip, a first package substrate 2 on which the sensor chip 1 is flip-chip mounted on one surface side, and a first package A circuit unit Dc for processing an output signal of the sensor chip 1, comprising: a second package substrate 3 sealed around the sensor chip 1 on the one surface side of the package substrate 2; A plurality of through-hole wirings 24 formed on the surface of the package substrate 2 facing the sensor chip 1 and electrically connected to the sensor chip 1 and the circuit portion Dc are formed on the first package substrate 2. Yes.

  Here, the first package substrate 2 and the second package substrate 3 have a rectangular outer peripheral shape and have the same outer dimensions. On the other hand, the outer peripheral shape of the sensor chip 1 is rectangular, and the outer dimensions of the sensor chip 1 can be accommodated in the housing recess 32 formed on the second package substrate 3 facing the first package substrate 2. Is formed.

  The sensor chip 1 is made of an SOI wafer (SOI substrate) having an n-type silicon layer (active layer) 10c on an insulating layer (buried oxide film) 10b made of a silicon oxide film on a support substrate 10a made of a silicon substrate. The first package substrate 2 is formed by processing a second wafer made of a silicon wafer, and the second package substrate 3 is made of a silicon wafer. The third wafer is formed by processing. In the present embodiment, the first wafer constitutes the first semiconductor substrate, the second wafer constitutes the second semiconductor substrate, and the third wafer constitutes the third semiconductor substrate. . In the present embodiment, the surface of the silicon layer 10c, which is the main surface of the SOI wafer, is a (100) plane.

  The sensor chip 1 is a piezoresistive acceleration sensor chip, and piezoresistors Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 are formed on a movable part composed of a weight part 12 and each bending part 13 described later. Yes.

  The sensor chip 1 includes a frame portion 11 having a frame shape (in this embodiment, a rectangular frame shape), and a weight portion 12 disposed inside the frame portion 11 has four strip shapes having flexibility on one surface side. The frame portion 11 is supported so as to be swingable through the bent portion 13. In other words, the sensor chip 1 is swingably supported by the frame portion 11 via the four flexure portions 13 that are extended from the weight portion 12 in the four directions by the weight portion 12 disposed inside the frame-shaped frame portion 11. Has been. Here, the frame portion 11 is formed using the above-described SOI wafer support substrate 10a, insulating layer 10b, and silicon layer 10c. On the other hand, each bending part 13 is formed using the silicon layer 10 c in the SOI wafer and is sufficiently thinner than the frame part 11.

  The weight portion 12 is continuously integrated with each of the rectangular parallelepiped core portion 12a supported by the frame portion 11 via the four flexure portions 13 and the four corners of the core portion 12a as viewed from the one surface side of the sensor chip 1. And four accompanying portions 12b having a rectangular parallelepiped shape connected to each other. In other words, the weight portion 12 is formed integrally with the core portion 12a and the core portion 12a in which the other end portion of each bending portion 13 whose one end portion is connected to the inner side surface of the frame portion 11 is connected to the outer surface. It has four accompanying parts 12b arranged in the space between the part 12a and the frame part 11. That is, each appendage portion 12b is disposed in a space surrounded by the frame portion 11 and the core portion 12a and the two bent portions 13 and 13 extended in a direction orthogonal to each other when viewed from the one surface side of the sensor chip 1. In addition, a slit 14 is formed between each of the accompanying portions 12b and the frame portion 11, and the interval between the adjacent accompanying portions 12b with the bending portion 13 interposed therebetween is longer than the width dimension of the bending portion 13. Yes. Here, the core portion 12a is formed using the above-described SOI wafer support substrate 10a, the insulating layer 10b, and the silicon layer 10c, and each accompanying portion 12b is formed using the SOI wafer support substrate 10a. It is. Thus, on the one surface side of the sensor chip 1, the surface of each associated portion 12 b is located away from the plane including the surface of the core portion 12 a toward the other surface side of the sensor chip 1. In addition, what is necessary is just to form the above-mentioned frame part 11, the weight part 12, and each bending part 13 of the sensor chip 1 using a bulk micromachining technique.

  By the way, as shown in the lower right of each of FIGS. 1 and 2, one direction along one side of the frame portion 11 in a plane parallel to the one surface of the sensor chip 1 is the positive direction of the x-axis, and this one side is If one direction along the orthogonal sides is defined as the positive direction of the y-axis and one direction of the thickness direction of the sensor substrate 1 is defined as the positive direction of the z-axis, the weight portion 12 is extended in the x-axis direction to be the core portion 12a. The pair of flexible portions 13 and 13 sandwiching the core portion 12 and the pair of flexible portions 13 and 13 extending in the y-axis direction and sandwiching the core portion 12a are supported by the frame portion 11. Become. In the orthogonal coordinates defined by the above-described three axes of the x-axis, y-axis, and z-axis, the origin is the center position of the weight 12 on the surface of the sensor chip 1 formed by the silicon layer 10c.

  The bending portion 13 (the bending portion 13 on the right side in FIG. 2) extending from the core portion 12a of the weight portion 12 in the positive direction of the x-axis has a pair of piezoresistors Rx2 and Rx4 formed in the vicinity of the core portion 12a. In addition, one piezoresistor Rz2 is formed in the vicinity of the frame portion 11. On the other hand, the bending portion 13 (left bending portion 13 in FIG. 2) extending from the core portion 12a of the weight portion 12 in the negative direction of the x-axis has a pair of piezoresistors Rx1 and Rx3 in the vicinity of the core portion 12a. In addition to being formed, one piezoresistor Rz3 is formed in the vicinity of the frame portion 11. Here, the four piezoresistors Rx1, Rx2, Rx3, and Rx4 formed in the vicinity of the core portion 12a are formed to detect acceleration in the x-axis direction, and the planar shape is an elongated rectangular shape. Wiring (diffuse layer wiring, metal not shown) formed in the sensor chip 1 so as to constitute the left bridge circuit Bx in FIG. 3 is formed so that the longitudinal direction coincides with the longitudinal direction of the bending portion 13. Connected by wiring). Note that the piezoresistors Rx1 to Rx4 are formed in a stress concentration region where stress is concentrated in the bent portion 13 when acceleration in the x-axis direction is applied.

  Further, the bending portion 13 (the upper bending portion 13 in FIG. 2) extended from the core portion 12a of the weight portion 12 in the positive direction of the y-axis is formed by a pair of piezoresistors Ry1 and Ry3 in the vicinity of the core portion 12a. In addition, one piezoresistor Rz1 is formed in the vicinity of the frame portion 11. On the other hand, the bending portion 13 (lower bending portion 13 in FIG. 2) extended from the core portion 12a of the weight portion 12 in the negative direction of the y-axis has a pair of piezoresistors Ry2 and Ry4 in the vicinity of the core portion 12a. At the same time, one piezoresistor Rz4 is formed at the end on the frame 11 side. Here, the four piezoresistors Ry1, Ry2, Ry3, and Ry4 formed in the vicinity of the core portion 12a are formed to detect acceleration in the y-axis direction, and the planar shape is an elongated rectangular shape. The wiring (not shown) (diffuse layer wiring, metal) formed in the sensor chip 1 so as to constitute the central bridge circuit By in FIG. 3 is formed so that the longitudinal direction coincides with the longitudinal direction of the bending portion 13. Connected by wiring). Note that the piezoresistors Ry1 to Ry4 are formed in a stress concentration region where stress is concentrated in the bent portion 13 when acceleration in the y-axis direction is applied.

  Further, the four piezoresistors Rz1, Rz2, Rz3, Rz4 formed in the vicinity of the frame portion 11 are formed for detecting acceleration in the z-axis direction, and constitute the right bridge circuit Bz in FIG. In this way, the sensor chip 1 is connected by a wiring (a diffusion layer wiring, a metal wiring, etc.) not shown. However, the piezoresistors Rz1 and Rz4 formed in one set of the bent portions 13 and 13 of the two bent portions 13 and 13 are formed so that the longitudinal direction thereof coincides with the longitudinal direction of the bent portions 13 and 13. On the other hand, the piezoresistors Rz2 and Rz3 formed in the other set of flexures 13 and 13 are formed such that the longitudinal direction coincides with the width direction (short direction) of the flexures 13 and 13. Yes.

  The piezoresistors Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4, and the diffusion layer wirings described above are formed by doping p-type impurities with appropriate concentrations at respective formation sites in the silicon layer 10c. .

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

  Now, assuming that acceleration is applied to the sensor chip 1 in the positive direction of the x-axis with no acceleration applied to the sensor chip 1, the frame portion 11 is caused by the inertial force of the weight 12 acting in the negative direction of the x-axis. Accordingly, the weight 12 is displaced, and as a result, the bending portions 13 and 13 whose longitudinal direction is the x-axis direction are bent, and the resistance values of the piezoresistors Rx1 to Rx4 formed in the bending portions 13 and 13 are changed. Will do. In this case, the piezoresistors Rx1 and Rx3 are subjected to tensile stress, and the piezoresistors Rx2 and Rx4 are subjected to compressive stress. In general, a piezoresistor has a characteristic that a resistance value (resistivity) increases when subjected to a tensile stress, and a resistance value (resistivity) decreases when subjected to a compressive stress. The value increases, and the resistance values of the piezoresistors Rx2 and Rx4 decrease. Therefore, if a constant DC voltage is applied from the external power source between the pair of input terminals VDD and GND shown in FIG. 3, the potential difference between the output terminals X1 and X2 of the left bridge circuit Bx shown in FIG. It changes according to the magnitude of the acceleration in the x-axis direction. Similarly, when acceleration in the y-axis direction is applied, the potential difference between the output terminals Y1 and Y2 of the central bridge circuit By shown in FIG. 3 changes according to the magnitude of the acceleration in the y-axis direction, and the z-axis When acceleration in the direction is applied, the potential difference between the output terminals Z1 and Z2 of the right bridge circuit Bz shown in FIG. 3 changes according to the magnitude of acceleration in the z-axis direction. Thus, the sensor chip 1 detects accelerations in the x-axis direction, the y-axis direction, and the z-axis direction that act on the sensor chip 1 by detecting changes in the output voltages of the bridge circuits Bx to Bz. Can be detected. In the sensor chip 1, an insulating film 16 composed of a silicon oxide film on the silicon layer 10c and a silicon nitride film on the silicon oxide film is formed on the one surface side. On the insulating film 16, A plurality of (in this embodiment, eight) pads 19 are formed, and each pad 19 has one of input terminals VDD, GND and output terminals X1, X2, Y1, Y2, Z1, and Z2, respectively. It is composed.

  On the other hand, the circuit portion Dc of the first package substrate 2 is an integrated circuit (CMOS IC) using CMOS, and an integrated circuit that cooperates with the sensor chip 1 is formed. Here, the integrated circuit of the circuit unit Dc is a signal processing circuit that outputs the signal output from the bridge circuits Bx, By, Bz of the sensor chip 1 by performing signal processing such as amplification, offset adjustment, temperature compensation, etc. An EEPROM or the like that stores data used in the processing circuit is integrated. In short, the signal processing circuit includes an amplifier circuit that amplifies the output signal of the sensor chip 1, an offset adjustment circuit that adjusts an offset (offset voltage) of the output signal, and the temperature of the output signal of the sensor chip 1 based on the output of the temperature detection unit. A temperature compensation circuit that performs compensation is integrated.

  The first package substrate 2 has a plurality of through holes 22 penetrating in the thickness direction, and a thermal oxide film (silicon oxide film) straddling both surfaces in the thickness direction and the inner surface of each through hole 22. An insulating film 23 is formed, and a part of the insulating film 23 is interposed between the through-hole wiring 24 and the inner surface of the through-hole 22. Here, the plurality of through-hole wirings 24 of the first package substrate 2 are formed apart from each other in the circumferential direction of the first package substrate 2. In addition, although Cu is employ | adopted as a material of the through-hole wiring 24, not only Cu but Ni etc. may be employ | adopted, for example.

  Further, the first package substrate 2 has a plurality of metal layers 29 for electrical connection formed on one surface side (the surface facing the sensor chip 1), and is composed of the sensor chip 1 and the circuit portion Dc. The sensor circuit is arranged at a position overlapping the pad 19 of the sensor chip 1 in the thickness direction of the first package substrate 2 so that the sensor circuit can be appropriately connected to the external circuit via a plurality of external connection electrodes 25 described later. The electrical connection metal layer 29 is joined and electrically connected to the pad 19 of the sensor chip 1, and the electrical connection metal layer 29 and the through-hole wiring 24 are electrically connected.

  Here, in the metal layer for electrical connection 29, a Ti film for improving adhesion is interposed between the Au film for bonding and the insulating film. In other words, the electrical connection metal layer 29 is configured by a laminated film of a Ti film formed on the insulating film 23 and an Au film formed on the Ti film. In the present embodiment, a Ti film is interposed between the Au film and the insulating film 23 as an adhesion improving layer. However, the material of the adhesion layer is not limited to Ti, for example, Cr, Nb, Zr, TiN, TaN, etc. may be used. In the first package substrate 2, the multilayer structure portion 17 formed by the multilayer wiring technique is formed on the insulating film 23 in a portion corresponding to the formation portion of the circuit portion Dc. The multilayer structure portion 17 is composed of a wiring layer, an interlayer insulating film, a passivation film, and the like.

  The first package substrate 2 has a plurality of external connection electrodes 25 electrically connected to the respective through-hole wirings 24 on the other surface side (surface side opposite to the sensor chip 1 side). Is formed. Here, each external connection electrode 25 is constituted by a laminated film of a Ti film, a Cu film, a Ni film, and an Au film laminated in the thickness direction, and the uppermost layer is an Au film.

  The external connection electrode 25 is electrically connected to the above-described bridge circuits Bx, By, Bz through the circuit portion Dc, and the above-described bridge circuits Bx, By, Bz without passing through the circuit portion Dc. Although some are electrically connected, all the external connection electrodes 25 may be electrically connected to the above-described bridge circuits Bx, By, Bz through the circuit portion Dc.

  By the way, as described above, the first package substrate 2 detects the ambient temperature and outputs a voltage value corresponding to the ambient temperature, and the output signal of the sensor chip 1 based on the output of the temperature detector. A circuit portion Dc including a temperature compensation circuit for correcting the temperature is formed, and the temperature detection unit is configured by a CMOS parasitic diode of the circuit unit Dc (that is, the temperature detection unit is the temperature of the forward voltage of the diode). The temperature is detected not only by the parasitic diode but also by, for example, a polycrystalline silicon diode, or a temperature sensor comprising a resistance temperature element such as a thermistor or a platinum resistance temperature detector. You may comprise by.

In the second package substrate 3, a housing recess 32 for housing the sensor chip 1 is formed on the surface facing the first package substrate 2, and the first package substrate 2 and the second package Peripheral portions with the substrate 3 are joined over the entire circumference. Here, in this embodiment, the first package substrate 2 and the second package substrate 3 are directly bonded by room temperature bonding of a combination of Si—SiO ₂ , but a combination of Si—Si or SiO it may be directly bonded by room-temperature bonding of ₂ -SiO ₂ combination to form a metal layer for sealing with a Au film on the surface side of each other in the circumferential portion of both room-temperature bonding of a combination of Au-Au May be joined directly. Further, instead of the Au film, an Al film or a Cu film may be employed, and direct bonding may be performed by room temperature bonding of an Al—Al combination or a Cu—Cu combination. In the room temperature bonding method, before bonding, each bonding surface is irradiated with argon plasma, ion beam or atomic beam in vacuum to clean and activate each bonding surface, and then the bonding surfaces are brought into contact with each other. Bonding is performed at room temperature (for example, 27 ° C.). When the acceleration sensor device of this embodiment is manufactured, the first package substrate 2 and the second package substrate 3 are bonded at the wafer level. In short, at the time of manufacturing the acceleration sensor device of the present embodiment, a second wafer and a second package substrate on which a large number of first package substrates 2 are formed and flip-chip mounted on a large number of separated sensor chips 1. A dicing process is performed in which a plurality of 3 formed wafers 3 are bonded at the wafer level and then cut into individual acceleration sensor devices.

  In the present embodiment, since the room temperature bonding method is employed as the bonding method between the first package substrate 2 and the second package substrate 3, the first package substrate 2 and the second package substrate are used. 3 is not required to be heated at the time of joining to the sensor chip 3, and the residual stress of the sensor chip 1 can be reduced. Here, in this embodiment, since the sensor chip 1 and each package substrate 2, 3 are formed of Si, which is the same semiconductor material, the difference in linear expansion coefficient between the sensor chip 1 and each package substrate 2, 3. Can reduce the influence of the stress (residual stress in the sensor chip 1) on the resistance values of the piezoresistors Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4, so that the stress is output from the bridge circuits Bx, By, Bz. The influence on the signal can be reduced, and when each of the package substrates 2 and 3 is formed of a material different from that of the sensor chip 1, the output is larger than when both of the package substrates 2 and 3 are formed of a different material. Variations in characteristics (sensor characteristics) can be reduced. The sensor chip 1 is formed by processing an SOI wafer. However, the sensor chip 1 is not limited to the SOI wafer, and may be formed by processing a silicon wafer, for example.

  The storage recess 32 of the second package substrate 3 is formed by using a lithography technique and an etching technique. Here, in the present embodiment, the depth of the storage recess 32 is formed so that the displacement space of the weight portion 12 is formed between the inner bottom surface of the storage recess 32 in the second package substrate 3 and the sensor chip 1. The size is set. In short, in the acceleration sensor device of the present embodiment, the sensor chip 1 is flip-chip mounted on the first package substrate 2 via the bumps 9, and the first package substrate 2 and the first package substrate are mounted. A package is constituted by the second package substrate 3 joined to the first package substrate 2 so as to surround the sensor chip 1 on the one surface side of the above-mentioned 2.

  The acceleration sensor device of the present embodiment is used by being mounted on a mounting substrate (for example, a glass epoxy resin substrate, for example) as shown in FIG. 1, and in the illustrated example, the acceleration sensor device and the mounting substrate are used. Since the joint portion 50 with 40 is formed by Au bumps, the size of each external connection electrode 25 can be reduced as compared with the case where the joint portion 50 is formed by solder (for example, by soldering). When forming, it is desirable to set the size to 200 μm □ or more, but when forming with Au bumps, it is possible to set the size to 100 μm □ or less.

  By the way, the sensor chip 1 and the first package substrate 2 in the acceleration sensor device of the present embodiment have the bumps 9 formed by the pads 19 of the sensor chip 1 and the metal layer 29 for electrical connection of the first package substrate 2. And are electrically connected. Therefore, in the sensor device according to the present embodiment, the distance between the movable portion of the sensor chip 1 and the first package substrate 2 can be controlled by the protruding height of the bumps 9, and the first package substrate 2 can be controlled. The displacement space of the movable part to the side can be secured. Therefore, in the acceleration sensor device of the present embodiment, the protruding dimension of the bump 9 is set such that the distance between the first package substrate 2 and the movable part defines the amount of displacement allowed for the movable part. In the present embodiment, the electrical connection metal layer 29 constitutes a pad in the first package substrate 2.

  Here, in the first package substrate 2, the bump 9 for flip chip mounting of the sensor chip 1 is formed on the surface of the pad 29 formed on the surface facing the sensor chip 1, and the pad of the sensor chip 1 is formed. 19 and the bump 9 are joined by room temperature bump joining.

  Here, the bumps 9 are composed of Au stud bumps. When the bumps 9 of the sensor chip 1 and the bumps 9 are bonded at room temperature with an Au—Au combination, first, the first package substrate 2 is formed. FIG. 4A shows a bump forming process in which bumps 9 made of Au stud bumps are formed on each pad 29 by a stud bump method (also called a ball bump method) using Au wires. Get the structure. The protruding dimension of the bump 9 formed in the bump forming step is set so that the distance between the first package substrate 2 and the movable part defines the amount of displacement allowed for the movable part.

  After the bump formation step described above, as shown in FIG. 4C, the first package substrate 2 and the sensor chip 1 are introduced into the chamber CH2, and then on the pads 29 of the first package substrate 2. An activation process is performed in which the formed bump 9 and the pad 19 of the sensor chip 1 are each irradiated with argon plasma, ion beam, or atomic beam in vacuum to clean and activate the surface.

  Subsequently, the pad 19 of the sensor chip 1 and the bump 9 on the pad 29 of the first package substrate 2 are aligned so as to overlap in the thickness direction of the sensor chip 1 in the chamber CH2, and the room temperature with respect to the sensor chip 1 is normal. A structure shown in FIG. 4D is obtained by performing a bonding process in which the pad 19 and the bump 9 of the sensor chip 1 are directly bonded (pressure-bonded) by applying an appropriate load under (for example, 27 ° C.). .

  By adopting the above-described method of bonding the pads 19 and the bumps 9 of the sensor chip 1 by the above-mentioned room temperature bump bonding, the pads 19 and the pads 19 are not heated in the bonding process without heating the sensor chip 1 and the first package substrate 2. Since the bumps 9 can be bonded, the deformation of the bumps 9 depends on the magnitude of the applied load, as compared with the case where the sensor chip 1 and the first package substrate 2 are directly bonded by applying a load under the heated condition. The amount can be controlled with high accuracy.

By the way, the bump 9 is not limited to the Au stud bump, and may be composed of an Au plating bump. When the bumps 9 are constituted by Au stud bumps as described above, the tip portions of the bumps 9 on the pads 29 of the first package substrate 2 between the bump formation process and the activation process described above. In order to reduce the hardness of 9b (soften the tip portion 9b), an annealing process may be performed in which each bump 9 is annealed, and each bump 9 made of an Au stud bump in an annealing process prior to the bonding process. Since the hardness of the tip end portion 9b is reduced, the bump 9 is easily deformed in the joining process, and the joining area is increased, so that the joining reliability is improved and the height variation of the bump 9 after joining can be reduced. Here, in the above-described annealing step, as shown in FIG. 4B, after the first package substrate 2 is introduced into the chamber CH1, the bump 9 is formed in an inert gas (for example, N ₂ gas) atmosphere. Is annealed under conditions of a predetermined annealing temperature and a predetermined annealing time, but the annealing temperature and the annealing time are at a level that does not apply a thermal load to the circuit portion Dc of the first package substrate 2 (that is, a thermal cause). The level may be set so as not to adversely affect. In the present embodiment, as described above, each pad 29 is formed of a laminated film of a Ti film and an Au film as an adhesion layer. However, the adhesion layer is formed of Au under each pad 29 in an annealing process. It also functions as a diffusion barrier film that prevents diffusion. In performing the above-described room temperature bump bonding, the chamber CH1 and the chamber CH2 to be used may be separate or the same chamber. Moreover, you may utilize the multi-chamber provided with chamber CH1 and chamber CH2. Further, a flattening step (leveling step) for flattening (leveling) the tip portion 9b of each bump 9 may be performed between the bump forming step and the annealing step, and by performing the flattening step, As a result, the bonding reliability is improved and the height variation of the bump 9 after bonding can be reduced. The bump 9 may be formed not on the pad 29 of the first package substrate 2 but on the pad 19 of the sensor chip 1. In this case, the bump 9 is formed on the surface of the pad 19 of the sensor chip 1. The bumps 9 and the pads 29 of the first package substrate 2 may be joined by room temperature bump bonding.

  In the acceleration sensor device of the present embodiment described above, the sensor chip 1 is accommodated in an airtight space surrounded by the first package substrate 2 and the second package substrate 3, and the output signal of the sensor chip 1 is signaled. Since the circuit portion Dc to be processed is formed on the sensor chip 1, the influence of disturbance such as electric noise and temperature can be suppressed, and high accuracy can be achieved. In addition, the sensor chip 1 and the first package substrate 2, the bump 9 formed on the surface of one pad 29 of the pads 19, 29 formed on the respective opposing surfaces and the other pad 19 are joined by room temperature bump bonding. When the flip chip mounting is performed on the first package substrate 2, no thermal load is applied to the sensor chip 1 and the circuit portion Dc of the first package substrate 2. Nsachippu thermal stress can be prevented from occurring in the movable portion 1, thereby the accuracy of the output. In the acceleration sensor device of the present embodiment, the circuit unit Dc includes a temperature detection unit that detects the ambient temperature and a temperature compensation circuit that corrects the output signal of the sensor chip 1 based on the output of the temperature detection unit. Therefore, the influence of temperature can be suppressed and high accuracy can be achieved.

  Further, in the acceleration sensor device of the present embodiment, the first package substrate 2 also serves as a stopper that limits the movable range of the movable portion, and the protruding dimension of the bump 9 is the same as that of the first package substrate 2 and the movable portion. Is set so as to define the amount of displacement allowed for the movable part, so that the load applied to the bumps 9 at room temperature when the sensor chip 1 is flip-chip mounted on the first package substrate 2 Thus, the deformation amount of the bump 9 in the thickness direction of the first package substrate 2 can be controlled, and the distance between the movable portion and the first package substrate 2 can be accurately controlled. Compared to applying a load under moderate heating conditions, can the variation of the displacement allowed for the movable part be reduced for each product (reproducibility can be improved)? , Attained as a result, the improvement of reliability.

  In the above-described embodiment, the circuit portion Dc is formed on the surface of the first package substrate 2 facing the sensor chip 1, but a part of the circuit portion Dc is formed on the frame portion 11 of the sensor chip 1. It may be formed on the side facing the first package substrate 2. By adopting such a configuration, the circuit function of the circuit part Dc can be expanded or added, and the circuit part Dc can be multi-functionalized. I can plan. In addition, regarding the surface layout of the circuit portion Dc in the first package substrate 2, the circuit portion Dc except for an area where the movable portion of the sensor chip 1 may collide when excessive acceleration is applied to the sensor chip 1. , The reliability of the circuit portion Dc can be improved.

  By the way, in the above-mentioned embodiment, although the sensor part used the acceleration sensor chip | tip which the sensor part was equipped with several piezoresistors Rx1-Rz4, Ry1-Ry4, Rz1-Rz4 as the sensor chip 1, it illustrated, The sensor device to which the technical idea is applied is not limited to the one having a movable part like the acceleration sensor device, and may be, for example, an infrared sensor device. Here, when the technical idea of the present invention is applied to an infrared sensor device, for example, the sensor portion of the sensor chip 1 is replaced with an infrared detector that detects infrared rays (for example, a thermistor type sensing element, a pyroelectric type sensing element). Element, thermopile type sensing element, resistance bolometer type sensing element, etc., and the circuit unit Dc is integrated with an amplifier circuit for amplifying the output signal of the infrared detector, a window comparator at the subsequent stage of the amplifier circuit, etc. Consists of a signal processing circuit composed of an integrated circuit, and condenses infrared rays from the outside onto the light receiving surface of the infrared detector at an appropriate portion of the package constituted by the first package substrate and the second package substrate. What is necessary is just to form a lens part integrally. In such an infrared sensor device, the wiring length between the infrared detection unit and the amplifier circuit can be shortened, noise from the wiring connecting the two can be prevented, and light from the outside can be prevented from entering the circuit unit. Since incidence can be prevented by the package, noise due to optical excitation of carriers in the circuit portion can be prevented, and high sensitivity can be achieved. In addition, the sensor unit of the sensor chip 1 is not limited to one in which the infrared detection unit is configured by one sensing element, and may be an array type in which a plurality of sensing elements are arranged in an array, or a plurality of different types. It may be of a composite type provided with the sensing element, and the circuit configuration of the circuit unit Dc may be appropriately changed according to the configuration of the sensor unit.

It is a schematic sectional drawing of the state which mounted the acceleration sensor apparatus of Embodiment 1 on the mounting board | substrate. It is a schematic plan view of the sensor chip in the same acceleration sensor device. It is a circuit diagram of the sensor part in an acceleration sensor device same as the above. It is explanatory drawing of the manufacturing method of an acceleration sensor apparatus same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor chip 2 1st package substrate 3 2nd package substrate 9 Bump 11 Frame part 12 Weight part 13 Deflection part 19 Pad 24 Through-hole wiring 29 Electric connection metal layer (pad)
Dc circuit part

Claims (3)

  A sensor chip formed using the first semiconductor substrate, a first package substrate formed using the second semiconductor substrate and having the sensor chip flip-chip mounted on one surface side, and a third semiconductor substrate And a second package substrate sealed in a form surrounding the sensor chip on the one surface side of the first package substrate, and a circuit unit for signal processing the output signal of the sensor chip, The first package substrate is formed on the surface facing the sensor chip, and the first package substrate is formed with a through-hole wiring electrically connected to the sensor chip and the circuit unit. The bump formed on the surface of one of the pads formed on each of the opposing surfaces of the chip and the first package substrate is in contact with the other pad by room temperature bump bonding. Sensor device characterized by comprising been.   The sensor chip is an acceleration sensor chip in which a movable part is provided with a piezoresistor, and the circuit unit is a temperature detection unit that detects an ambient temperature and an output signal of the sensor chip based on an output of the temperature detection unit The sensor device according to claim 1, further comprising a temperature compensation circuit that corrects the error.   3. The protruding dimension of the bump is set such that a distance between the first package substrate and the movable part defines a displacement amount allowed for the movable part. Sensor device.

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