JP2007266319A - Method of manufacturing sensor package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a sensor package wherein the inspection of the electric characteristics relative to sensor substrates in each of which sensing portions and a circuit portion are formed can be performed easily and in detail. <P>SOLUTION: The sensor substrates 1 each of which has sensing portions and a circuit portion are formed on a sensor wafer 10. Also, electrode forming substrates 2 each of which has through-hole wirings to be connected electrically with the terminals provided in each sensor substrate 1 are formed on a package wafer 20. After joining to each other the sensor wafer 10 and the package wafer 20, the electric characteristics of the sensing portions and the circuit portion which are present in each sensor substrate 1 formed on the sensor wafer 10 are inspected comprehensively. After the inspection, the laminates each of which comprises the sensor substrate 1 and the electrode forming substrate 2 are cut individually and separated form each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sensor package manufacturing method in which a sensor substrate having a sensing portion and an electrode forming substrate having a through-hole wiring electrically connected to the sensor substrate are joined.

Conventionally, a substrate wafer formed with a plurality of electronic devices such as SAW devices and a cover wafer formed with through-hole wiring (conductive paths) electrically connected to the electronic devices are bonded at the wafer level, and then cut. A technique of forming individual packages by separating them is known as a semiconductor device manufacturing technique (see, for example, Patent Document 1). Japanese Patent Application Laid-Open No. H10-228561 describes that after bonding a substrate wafer and a cover wafer, an electronic device is electrically tested at a wafer level using a probe.
JP-A-6-318625

  In the technique described in Patent Document 1, a single electronic device such as a SAW device is electrically tested at the wafer level, and this type of electronic device is not a circuit until it is combined with other circuit units. Therefore, even if the electronic device is electrically tested alone, the electrical characteristics when the circuit part is configured must be re-inspected, and the inspection process is troublesome twice. It has become.

  The present invention has been made in view of the above-described reasons, and the object of the present invention is to provide a sensor package that can simultaneously inspect the sensing portion and the circuit portion in the manufacturing process of the sensor package so as to save labor in the inspection step. It is to provide a manufacturing method.

  According to the first aspect of the present invention, there is provided a step of forming on a sensor wafer a sensor substrate comprising a sensing portion and an integrated circuit and having a circuit portion cooperating with the sensing portion, and a through-hole wiring electrically connected to a terminal provided on the sensor substrate Forming a substrate having an electrode forming substrate on the package wafer, bonding the sensor wafer and the package wafer and electrically connecting the terminals provided on the sensor substrate and the through-hole wiring, and the sensing unit and the circuit after bonding The method includes a step of inspecting electrical characteristics with the part, and a step of individually cutting and separating the laminate of the sensor substrate and the electrode forming substrate after the inspection.

  According to this method, since the electrical characteristics of the sensing unit and the circuit unit formed on the sensor substrate are inspected at the wafer level, compared with the case where the electrical characteristics are inspected after being individually separated, alignment and the like are performed. There is little time and work time required for inspection can be shortened. In addition, since the sensing part and the circuit part are formed on the sensor board, the sensing part and the circuit part can be inspected at the same time in the manufacturing process of the sensor package, thereby making it possible to save labor in the inspection process. Become.

  The invention of claim 2 is characterized in that in the invention of claim 1, a step of inspecting electrical characteristics of the sensing unit and the circuit unit is added before bonding the package wafer to the sensor wafer. To do.

  According to this method, since the sensing unit and the circuit unit are inspected before the package wafer is bonded to the sensor wafer, the inspection can be performed in a state where the sensing unit and the circuit unit are exposed. That is, since it is not necessary to separately provide an inspection electrode on the package wafer, it is not necessary to form an extra through-hole wiring for inspection on the electrode forming substrate, and the cost can be reduced. Further, the terminals provided on the sensor substrate are only required to be electrically connected to the through-hole wiring, and are formed in a small area. Therefore, a large number of inspection electrodes may be provided on the sensing unit and the circuit unit. Possible and various inspections are possible. In addition, since the inspection process is performed in one process before joining, the inspection of the sensing unit and the circuit unit can be performed collectively, and if there is a defective part, the defective part can be easily identified. In addition, since the electrical characteristics of the sensing unit and circuit unit are inspected individually, detailed inspection of the electrical characteristics is possible, and if a defect occurs in one of the sensing unit and circuit unit, the location where the defect has occurred is identified. It becomes easy to do. If a defect occurrence location is specified, feedback to a location where a failure occurs in the process becomes easy.

  In the embodiment described below, the support portion surrounds the mass body, and the support portion and the mass body are connected via a flexible flexure portion that is extended from the mass body in all directions. An example of a configuration in which a strain gauge made of a piezoresistor is provided to detect a stress generated in a flexure portion as the mass body is displaced by the strain gauge, and an acceleration is detected using a resistance change of the strain gauge. That is, an example in which the sensing unit constitutes an acceleration sensor is shown. In addition, by arranging strain gauges in the flexures that extend in four directions from each mass body, two axes in directions orthogonal to each other in a plane including the four flexures, and perpendicular to these two axes Thus, it is possible to individually detect the acceleration in a total of three axes including one axis in the direction to be performed. However, if the sensor device includes a mass body, the technical idea of the present invention can be applied to a gyro sensor instead of an acceleration sensor, and the detection of the displacement of the mass body is not limited to the piezoresistor, but is shown as the prior art. You may employ | adopt the structure detected as a change of an electrostatic capacitance like a technique. Moreover, a bending part is not limited to the structure extended in all directions from a mass body.

  As shown in FIG. 4, the sensor device of this embodiment includes a sensor substrate 1 formed of a semiconductor substrate on which a sensing portion Ds and a circuit portion Dc are formed, and a pad electrode 25 for connecting an external circuit on one surface in the thickness direction (see FIG. 4). 4 is formed on the surface of the sensor substrate 1 in the thickness direction (upper surface of FIG. 4) and the other surface of the sensor substrate 1 in the thickness direction (lower surface of FIG. 4). And a cover substrate 3 made of a semiconductor substrate sealed. That is, the sensor device is composed of a laminate of three semiconductor substrates. The sensor substrate 1, the electrode forming substrate 2, and the cover substrate 3 have a rectangular shape (square in the illustrated example), and the electrode forming substrate 2 and the cover substrate 3 have the same outer dimensions as the sensor substrate 1.

  The sensor substrate 1 is formed by processing a sensor wafer made of an SOI wafer. The SOI wafer used here has a support substrate 10a made of a silicon substrate, and an n-type silicon layer is formed on one surface in the thickness direction of the support substrate 10a via an insulating layer 10b as a buried oxide film made of a silicon oxide film. An active layer 10c made of is formed. Further, in the sensor substrate 1, an insulating film 16 made of a laminated film of a silicon oxide film and a silicon nitride film is formed on the surface of the active layer 10c. Therefore, the surface of the active layer 10 c is covered with the insulating film 16. The electrode forming substrate 2 and the cover substrate 3 are formed by processing different silicon wafers. That is, an SOI wafer is used as the semiconductor substrate of the sensor substrate 1, and a silicon wafer is used as the semiconductor substrate of the electrode forming substrate 2 and the cover substrate 3.

  When the dimension example in this embodiment is illustrated, the thickness dimension of the support substrate 10a in an SOI wafer is 300-500 micrometers, the thickness dimension of the insulating layer 10b is 0.3-1.5 micrometers, and the thickness dimension of the silicon layer 10c is 4-10 micrometers. To do. The thickness dimension of the silicon wafer as the package wafer for forming the electrode forming substrate 2 is 200 to 300 μm, and the thickness dimension of the silicon wafer for forming the cover substrate 3 is 100 to 300 μm. However, these numerical values are not intended to limit, but are values indicating a guide. The surface of the silicon layer 10c, which is one surface of the SOI wafer, is a (100) plane.

  As shown in FIGS. 3, 5, 6, and 7, the sensor substrate 1 is supported in a frame shape (when viewed from a direction orthogonal to the thickness direction) in a plan view (in this embodiment, a rectangular frame shape). It is formed in a shape including a mass body 12 at the center of the portion 11. That is, the mass body 12 is surrounded by the support portion 11. In the present embodiment, the center of the support portion 11 and the center of the mass body 12 substantially coincide with each other in plan view. The support portion 11 and the mass body 12 are connected by four flexure portions 13 extending from the mass body 12 in all directions.

  Each bending part 13 has the flexibility formed in strip shape. Each bending portion 13 is arranged on two straight lines that pass through the center of the mass body 12 and are orthogonal to each other in plan view. In other words, each of the two bent portions 13 is arranged on each straight line orthogonal to each other. With this configuration, the mass body 12 can be displaced with respect to the support portion 11. The support portion 11 and the mass body 12 use the entire support substrate 10a, insulating layer 10b, and active layer 10c of the SOI wafer, and the bending portion 13 removes the support substrate 10a and insulating layer 10b from the SOI wafer, thereby activating the active layer 10c. Use only. Therefore, the bending portion 13 is formed to be sufficiently thin as compared with the support portion 11 and the mass body 12.

  The mass body 12 includes a core portion 12a that is coupled to the support portion 11 via four flexure portions 13, and four leaf portions 12b that are continuously and integrally connected to the core portion 12a. In the plan view, the mass body 12 is arranged so that one of the five squares is centered on the other square so as to be rotationally symmetric about four times, and the other is located at each corner of the central square. Are formed in a shape in which one corner of each square is overlapped. In the present embodiment, the portion corresponding to the square arranged at the center corresponds to the core portion 12a, and the portion of the other squares excluding the portion overlapping with the core portion 12a corresponds to the leaf portion 12b. In other words, the core portion 12a has a square shape in plan view, and the leaf portion 12b has a shape in which one corner portion of the square is cut out. The bending portion 13 is integrally continuous with the central portion of each side of the core portion 12a, and leaf portions 12b are provided on both sides in the width direction of each bending portion 13 (a direction orthogonal to the extending direction of the bending portion 13 in plan view). Be placed.

  Each leaf portion 12b is disposed in a space surrounded by the two bending portions 13 and the support portion 11 that are orthogonal to each other in plan view, and the sensor substrate 1 is interposed between each leaf portion 12b and the support portion 11, respectively. A slit 14 penetrating in the thickness direction is formed. Moreover, the bending part 13 and each leaf part 12b are spaced apart, and the space | interval of each pair of leaf part 12b arrange | positioned on both sides of the bending part 13 is larger than the width dimension of each bending part 13. FIG.

  In addition, the support part 11, the mass body 12, and the bending part 13 in the sensor board | substrate 1 can be formed using the lithography technique and etching technique known as a manufacturing technique of a semiconductor device.

  By the way, since the illustrated example is a triaxial acceleration sensor, a direction in which acceleration is detected is defined. A direction orthogonal to the thickness direction of the sensor substrate 1 is defined as a z-axis direction, and a direction from the support substrate 10a toward the active layer 10c is defined as a positive direction. The surface of the active layer 10c is the xy plane, and the center position of the mass body 12 is the origin in the xy plane. The x-axis direction and the y-axis direction are directions in which the bending portion 13 extends from the core portion 12a, respectively, and define a positive direction in the right-handed system. For example, the right direction in FIG. 5 is the positive direction in the x-axis direction, and the upward direction is the positive direction in the y-axis direction. Therefore, the mass body 12 is supported by the two bent portions 13 in the x-axis direction disposed with the core portion 12a interposed therebetween and the two bent portions 13 in the y-axis direction disposed with the core portion 12a interposed therebetween. It is connected to the part 11.

  A pair of piezoresistors Rx2 is provided at one end on the core 12a side in the bending portion 13 that extends in the positive direction in the x-axis direction from the core 12a of the mass body 12 (rightward from the core 12a in FIG. 5). , Rx4, and one piezoresistor Rz2 is formed at one end on the support 11 side. Similarly, in the bending portion 13 extending in the negative direction in the x-axis direction from the core portion 12a (leftward from the core portion 12a in FIG. 5), a set of two piezoresistors Rx1 at one end portion on the core portion 12a side. , Rx3, and one piezoresistor Rz3 is formed at one end on the support 11 side.

  A pair of piezoresistors Ry1 at one end on the core 12a side is provided on the bending portion 13 that is extended from the core 12a of the mass body 12 in the positive direction in the y-axis direction (upward from the core 12a in FIG. 5). , Ry3, and one piezoresistor Rz1 is formed at one end on the support 11 side. Similarly, the bending portion 13 extended from the core portion 12a in the negative direction in the y-axis direction (downward from the core portion 12a in FIG. 5) has a pair of piezoresistors Ry2 at one end on the core portion 12a side. , Ry4 are formed, and one piezoresistor Rz4 is formed at one end on the support portion 11 side.

  In the two flexures 13 extended in the x-axis direction, the four piezoresistors Rx1, Rx2, Rx3, and Rx4 formed at one end on the core 12a side are for detecting acceleration in the x-axis direction. It is formed in a region where stress generated in the bending portion 13 is concentrated when acceleration in the x-axis direction acts on the mass body 12. The piezoresistors Rx1, Rx2, Rx3, and Rx4 are formed in a rectangular shape whose longitudinal direction is the x-axis direction in plan view. These piezo resistors Rx1, Rx2, Rx3, and Rx4 are connected so as to constitute the leftmost bridge circuit Bx in FIG.

  In the two flexures 13 extended in the y-axis direction, four piezoresistors Ry1, Ry2, Ry3, and Ry4 formed at one end on the core 12a side detect acceleration in the y-axis direction. For this reason, it is formed in a region where stress generated in the bending portion 13 is concentrated when acceleration in the y-axis direction acts on the mass body 12. The piezoresistors Ry1, Ry2, Ry3, Ry4 are formed in a rectangular shape whose longitudinal direction is the y-axis direction in plan view. These piezoresistors Ry1, Ry2, Ry3, and Ry4 are connected so as to form a central bridge circuit By in FIG.

  In the four flexures 13, four piezoresistors Rz1, Rz2, Rz3, and Rz4 formed at one end on the support 11 side are formed to detect acceleration in the z-axis direction. The piezoresistors Rz1, Rz2, Rz3, and Rz4 are all formed in a rectangular shape whose longitudinal direction is the y-axis direction. That is, the longitudinal directions of the piezoresistors Rz1 and Rz4 formed in the two flexures 13 extended in the y-axis direction coincide with the extension direction of the flexure 13 and the two flexures extended in the x-axis direction. The longitudinal direction of the piezoresistors Rz2 and Rz3 formed on 13 is orthogonal to the extending direction of the flexure 13. These piezoresistors Rz1, Rz2, Rz3, and Rz4 are connected so as to constitute the rightmost bridge circuit Bz in FIG.

  For the connection of each of the piezoresistors Rx1, Rx2, Rx3, Rx4, Ry1, Ry2, Ry3, Ry4, Rz1, Rz2, Rz3, Rz4, a diffusion layer wiring or a metal wiring formed on the sensor substrate 1 is used.

  In the circuit configuration shown in FIG. 9, input terminals T1 and T2 for applying a voltage to the three bridge circuits Bx, By and Bz are connected in common, and each bridge circuit Bx, By and Bz has an individual output terminal X1. , X2, Y1, Y2, Z1, Z2 are provided. In the present embodiment, the voltage applied to the input terminals T1 and T2 is a DC voltage, the voltage VDD is applied to the input terminal T1, and the input terminal T2 is connected to the circuit ground GND. Therefore, the stress generated in the bending portion 13 due to the displacement of the mass body 12 is caused by the piezoresistors Rx1, Rx2, Rx3, Rx4, Ry1, Ry2, Ry3, Ry4, Rz1, Rz2, Rz3, and Rz4. In addition, it is converted into an electric quantity (voltage) by the bridges Bx, By, Bz and output.

  Hereinafter, an operation example of the sensor substrate 1 will be described. Assuming that acceleration is applied in the positive direction in the x-axis direction to the sensor substrate 1 from a state in which no acceleration is applied to the sensor substrate 1, the inertial force of the mass body 12 acting in the negative direction in the x-axis direction is used. The mass body 12 is displaced with respect to the support portion 11, and the two bending portions 13 extended in the x-axis direction from the core portion 12a are bent to form the piezoresistors Rx1, Rx2, Rx3 formed in the bending portion 13. The resistance value of Rx4 changes. At this time, the piezoresistors Rx1 and Rx3 are subjected to tensile stress, and the piezoresistors Rx2 and Rx4 are subjected to compressive stress. In general, when a piezoresistor is subjected to a tensile stress, its resistance value (resistivity) increases, and when it receives a compressive stress, its resistance value (resistivity) decreases. Therefore, when acceleration acts in the positive direction in the x-axis direction, the resistance values of the piezo resistors Rx1 and Rx3 increase, and the resistance values of the piezo resistors Rx2 and Rx4 decrease. By this operation, the potential difference between the output terminals X1 and X2 of the leftmost bridge circuit Bx in FIG. 9 changes according to the magnitude of acceleration in the x-axis direction.

  Similarly, if the acceleration in the y-axis direction acts, the potential difference between the output terminals Y1 and Y2 of the center bridge circuit By in FIG. 9 changes according to the magnitude of the acceleration in the y-axis direction, and the acceleration in the z-axis direction. As a result, the potential difference between the output terminals Z1 and Z2 of the bridge circuit Bz at the right end of FIG.

  Therefore, by detecting the change in the output voltage of each bridge circuit Bx, By, Bz, the acceleration in the x-axis direction, the y-axis direction, and the z-axis direction acting on the sensor substrate 1 can be detected. In the present embodiment, the sensing body Ds is configured by the mass body 12, the four bending portions 13, and the piezoresistors Rx1, Rx2, Rx3, Rx4, Ry1, Ry2, Ry3, Ry4, Rz1, Rz2, Rz3, Rz4. .

  Since this embodiment is a triaxial acceleration sensor, the circuit unit Dc that cooperates with the sensing unit Ds includes a power supply circuit that applies a voltage to the input terminals T1 and T2 of the bridge circuits Bx, By, and Bz, and the bridge circuit Bx. , By, Bz output terminals X 1, X 2, Y 2, Y 2, Z 1, Z 2 are required to amplify the output voltage of the bridge circuits Bx, By, Bz, etc., and the circuit portion Dc is formed as an integrated circuit. Is done. The circuit portion Dc is formed on the active layer 10c of the sensor substrate 1 where the support substrate 10a is provided. That is, in the present embodiment, the support portion 11 and the mass body 12 are formed using the entire SOI wafer including the support substrate 10a, the insulating layer 10b, and the active layer 10c. The circuit part Dc is formed using the active layer 10c in the No. 12.

  However, since the support substrate 10 a does not exist in the bending portion 13 of the sensor substrate 1 and the bending portion 13 is deformed, the circuit portion Dc is not formed in the bending portion 13. In FIG. 3, the shaded area indicates a region where the circuit portion Dc can be formed. In this embodiment, it is essential to form the circuit portion Dc on the mass body 12, and the circuit portion Dc that cannot be formed within the area of the mass body 12 is formed on the support portion 11. The circuit part Dc formed in the support part 11 and the mass body 12 is connected by forming a diffusion layer wiring or a metal wiring in the bending part 13. That is, the flexible part 13 is provided with the internal wiring of the circuit part Dc.

  Thus, by providing a part of the circuit part Dc on the mass body 12, the area of the sensor substrate 1 can be reduced as compared with the case where the entire circuit part Dc is formed on the support part 11, and as a result. Thus, the sensor device can be reduced in size.

  A sealing metal layer 18 and a connection metal layer 19 are formed on one surface of the sensor substrate 1 (upper surface in FIG. 4). The connecting metal layer 19 is a part of metal wiring, and functions as a terminal 17 for connecting the sensing part Ds and the circuit part Dc to an external circuit. The terminal 17 is not only formed as the connecting metal layer 19 but also formed at a portion not connected to the periphery of the sensing portion Ds or an external circuit as shown in FIG. Terminals 17 around the sensing unit Ds are input terminals T1, T2 and output terminals X1, X2, Y2, Y2, Z1, Z2 of the bridge circuits Bx, By, Bz of the sensing unit Ds, and are not connected to an external circuit. The other terminal 17 is used for the inspection of the electrical characteristics of the circuit portion Dc. These terminals 17 are formed as rectangular pad electrodes.

  FIG. 8 shows the vicinity of the connection metal layer 19. Note that the illustration of the diffusion layer wiring is omitted. The sealing metal layer 18 is formed along the entire outer peripheral edge of the sensor substrate 1 and surrounds the sensing part Ds and the circuit part Dc. The connecting metal layer 19 is also disposed inside the sealing metal layer 18 in the support portion 11. The metal wiring including the connecting metal layer 19 and the sealing metal layer 18 are formed on the insulating film 16 covering the surface of the active layer 10c. Further, the sealing metal layer 18 and the connecting metal layer 19 are formed of the same metal material, and the sealing metal layer 18 and the connecting metal layer 19 are formed simultaneously and substantially in the same thickness. Can do.

  In the sensor substrate 1, the piezoresistors Rx1, Rx2, Rx3, Rx4, Ry1, Ry2, Ry3, Ry4, Rz1, Rz2, Rz3, Rz4 and the diffusion layer wiring are p-types with appropriate concentrations at respective formation sites in the active layer 10c. It is formed by doping impurities. Further, the metal wiring excluding the connection metal layer 19 is obtained by applying a lithography technique and an etching technique to a metal film (for example, an Al film, an Al—Si film, etc.) formed on the insulating film 16 by a sputtering method or a vapor deposition method. The metal wiring is electrically connected to the diffusion layer wiring through a contact hole provided in the insulating film 16.

  The sealing metal layer 18 and the connection metal layer 19 have a bonding Au film on the surface, and a Ti film for improving adhesion is interposed between the Au film and the insulating film 16. That is, the sealing metal layer 18 and the connection metal layer 19 are formed of a laminated film of a Ti film formed on the insulating film 16 and an Au film formed on the Ti film.

  The sealing metal layer 18 and the connection metal layer 19 have a Ti film thickness of 15 to 50 nm and an Au film thickness of 500 nm. The metal wiring film excluding the connection metal layer 19 The thickness is set to 1 μm. However, these numerical values are merely examples and are not intended to be limiting.

  As shown in FIG. 4, the electrode forming substrate 2 secures a displacement space for the mass body 12 and the bending portion 13 in the thickness direction of the sensor substrate 1 at the center of the surface facing the sensor substrate 1 (the lower surface in FIG. 4). Displacement recesses 21 are formed to perform (to regulate the displacement amount of the mass body 12). In addition, a sealing metal layer 28 is formed along the entire circumference of the outer peripheral edge of the electrode forming substrate 2 on the peripheral portion of the electrode forming substrate 2 facing the sensor substrate 1. The sealing metal layer 28 of the electrode forming substrate 2 is formed in a portion that overlaps the sealing metal layer 18 of the sensor substrate 1 when the electrode forming substrate 2 is superimposed on the sensor substrate 1. The metal layers 18 and 28 are bonded to each other so that the space between the sensor substrate 1 and the electrode forming substrate 2 is sealed.

  A plurality of through holes 22 penetrating in the thickness direction of the electrode forming substrate 2 are formed in a region of the electrode forming substrate 2 facing the sensor substrate 1 and between the sealing metal layer 28 and the displacement recess 21. Is formed. An insulating film 23 which is a silicon oxide film formed by thermal oxidation is continuously formed on both surfaces in the thickness direction of the electrode forming substrate 2 and the inner peripheral surface of the through hole 22. Further, a through-hole wiring 24 penetrating the front and back in the thickness direction of the electrode forming substrate 2 is formed in the through-hole 22. Therefore, a part of the insulating film 23 is interposed between the through-hole wiring 24 and the inner peripheral surface of the through-hole 22. The plurality of through-hole wirings 24 provided on the electrode forming substrate 2 are arranged apart from each other. Although it is desirable to employ Cu as the material of the through-hole wiring 24, it is not limited to Cu, and for example, Ni may be employed.

  A plurality of connection metal layers 29 electrically connected to the respective through-hole wirings 24 are formed in a portion surrounding the displacement recess 21 on the surface of the electrode forming substrate 2 facing the sensor substrate 1. The connecting metal layer 29 is disposed inside the sealing metal layer 28. A part of the connection metal layer 29 is electrically bonded to one end of the through-hole wiring 24, and the other part is arranged to be bonded to the connection metal layer 19 of the sensor substrate 1. That is, when the electrode forming substrate 2 is superimposed on the sensor substrate 1, the positions of the through-hole wiring 24 and the connection metal layer 19 corresponding to the through-hole wiring 24 are shifted. The connecting metal layer 29 and the sealing metal layer 28 are formed of the same metal material, and the connecting metal layer 29 and the sealing metal layer 28 can be formed simultaneously and substantially in the same thickness. .

  Further, in the sensor substrate 1, the connecting metal layer 19 is laminated with respect to other metal wirings, and the thickness dimension of the laminated part is larger than the part of the connecting metal layer 19 alone. Therefore, in the sensor substrate 1, the laminated portion of the connection metal layer 19 and the other metal wiring is positioned so as to be positioned in the displacement recess 21 provided in the electrode formation substrate 2 when it is superimposed on the electrode formation substrate 2. Is decided.

  The sealing metal layer 28 and the connection metal layer 29 are provided with a bonding Au film on the surface, and a Ti film for improving adhesion is interposed between the Au film and the insulating film 23. That is, the sealing metal layer 28 and the connection metal layer 29 are formed of a laminated film of a Ti film formed on the insulating film 23 and an Au film formed on the Ti film.

  The sealing metal layer 28 and the connecting metal layer 29 have a Ti film thickness of 15 to 50 nm and an Au film thickness of 500 nm. However, these numerical values are merely examples and are not intended to be limiting.

  A solder reflow pad electrode 25 serving as an electrode for connection to an external circuit is formed on the surface of the electrode forming substrate 2 in the thickness direction opposite to the surface facing the sensor substrate 1. Each pad electrode 25 is electrically connected to the other end of each through-hole wiring 24. Each pad electrode 25 has a rectangular outer shape (for example, a square shape), and is arranged on the surface of the electrode forming substrate 2 at substantially equal intervals. The size of each pad electrode 25 and the distance between adjacent pad electrodes 25 are designed so as not to fall below a size suitable for solder reflow.

  Since the number and layout of the pad electrodes 25 are various, the position of the connection metal layer 19 provided on the sensor substrate 1 is different from the position of the pad electrode 25 electrically connected to the connection metal layer 19. In some cases, a rewiring portion (not shown) may be provided in a part of the connection metal layer 29 and an electric circuit may be routed to enable electrical connection between each pad electrode 25 and the connection metal layer 19. it can. That is, according to the layout of the pad electrode 25 on the electrode forming substrate 2, the relative positions of the joint portion between the connection metal layer 19 and the connection metal layer 29 and the connection portion between the connection metal layer 29 and the through-hole wiring 24. A rewiring portion for adjusting a general positional relationship is formed.

  Each pad electrode 25 is composed of 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. Each pad electrode 25 is composed of at least two layers of metal films laminated in the thickness direction, and if the uppermost metal film is formed of Au and the metal film immediately below the uppermost layer is formed of Ni, Since the uppermost metal film is made of Au, oxidation can be prevented, and the metal film immediately below the uppermost layer is made of Ni, so that it can be compared with the case of being made of Cu. It becomes difficult to be eroded by the solder, and the film thickness can be reduced. Further, since the lowermost metal film in the thickness direction of each pad electrode 25 is formed of Ti, the adhesion between each pad electrode 25 and the insulating film 23 can be enhanced.

  The cover substrate 3 is sealed to the surface opposite to the electrode forming substrate 2 in the thickness direction of the sensor substrate 1. A displacement recess 31 that forms a space that allows displacement of the mass body 12 (regulates the amount of displacement of the mass body 12) is formed at the center of the surface of the cover substrate 3 that faces the sensor substrate 1. The depth of the displacement recess 31 is set to 5 to 10 μm, for example. The displacement recess 31 is formed using a lithography technique and an etching technique.

  Note that the displacement amount of the mass body 12 may be regulated by adjusting the thickness dimension of the mass body 12 instead of forming the displacement recess 31 in the cover substrate 3. That is, the thickness dimension of the part formed using the support substrate 10a of the SOI wafer in the core portion 12a and each leaf portion 12b of the mass body 12 is formed in the support portion 11 using the support substrate 10a. What is necessary is just to make it smaller than the thickness dimension of the site | part which exists. In this configuration, the difference between the thickness dimension of the support substrate 10 a in the mass body 12 and the thickness dimension of the support substrate 10 a in the support portion 11 is the displacement amount of the mass body 12 that is allowed in the thickness direction of the sensor substrate 1.

  In manufacturing the acceleration sensor described above, as shown in FIG. 1, a sensor wafer 10 (FIG. 1A) on which a large number of sensor substrates 1 are formed and a package wafer 20 on which a large number of electrode forming substrates 2 are formed. (FIG. 1 (b)) and a cap wafer 30 (FIG. 1 (c)) on which a large number of cover substrates 3 are formed are bonded to each other at the wafer level (FIG. 1 (d)), and then a dicing process (FIG. 1). (F)) is cut and separated individually. At the time of bonding at the wafer level, the sealing metal layer 18 and the connection metal layer 19 formed on the sensor substrate 1, and the sealing metal layer 28 and the connection metal layer 29 formed on the electrode forming substrate 2 are formed. The electrode forming substrate 2 is bonded to the sensor substrate 1 by being bonded to each other. Further, the sensor substrate 1 and the cover substrate 3 are joined to each other at the peripheral portions of the opposing surfaces. By adopting such a manufacturing process, the electrode forming substrate 2 and the cover substrate 3 have the same outer dimensions as the sensor substrate 1, and a small chip size package can be easily manufactured.

  Further, after the package wafer 20 is bonded to the sensor wafer 10, an inspection relating to the electrical characteristics of the sensing portion Ds and the circuit portion Dc is performed. By this inspection, not only the sensing portion Ds but also the comprehensive inspection including the circuit portion Dc becomes possible. Here, in addition to the through-hole wiring 24 for connecting to an external circuit, the package wafer 20 is formed with a through-hole wiring 24 electrically connected to a part of the terminals 17 for inspection. Even after bonding 10 and the package wafer 20, it is possible to individually inspect the electrical characteristics of the sensing portion Ds and the circuit portion Dc.

  In this inspection process, electrical characteristics such as wiring resistance, presence / absence of wiring short-circuiting, and variation in resistance value are inspected. In this inspection, as shown in FIG. 2A, the inspection probe 4 is brought into contact with the terminal 17 to be inspected. The inspection probe 4 is controlled by a robot and positioned so as to contact the terminal 17 at a desired position.

  Further, as shown in FIG. 2B, a plurality of inspection probes 4 may be held together by a holder 5. In this case, for example, a group in which a plurality of inspection probes 4 are arranged in accordance with the terminals 17 corresponding to the sensing part Ds and a plurality of inspection probes 4 are arranged in accordance with the terminals 17 corresponding to the circuit part Dc. If a group is configured, the sensing unit Ds and the circuit unit Dc can be collectively inspected. Furthermore, the inspection probes 4 corresponding to all terminals to be inspected in one sensor wafer 10 may be held by the holder 5 without being grouped. Alternatively, if the inspection probes 4 are arranged so as to straddle the plurality of sensor substrates 1 on the sensor wafer 10, it is possible to inspect the plurality of sensor substrates 1 at a time.

  By the way, as a joining method of the sensor substrate 1, the electrode formation substrate 2, and the cover substrate 3, it is desirable to reduce the residual stress of the sensor substrate 1 after joining. Therefore, it is desirable to employ a bonding method that enables bonding at a low temperature. Therefore, in this embodiment, a room temperature bonding method is adopted.

  In the room temperature bonding method, each bonding surface is cleaned and activated by irradiating the bonding surfaces with argon plasma, ion beam or atomic beam in vacuum before bonding, and then the bonding surfaces are brought into contact with each other. And apply an appropriate load at room temperature. At this time, the sealing metal layer 18 and the sealing metal layer 28 are bonded together, and at the same time, the connection metal layer 19 and the connection metal layer 29 are bonded, and the support portion of the sensor substrate 1 at room temperature. 11 and the peripheral portion of the cover substrate 3 are joined.

  In the sensor device of this embodiment, the bonding between the sensor substrate 1 and the electrode forming substrate 2 is an Au—Au bonding, and the bonding between the sensor substrate 1 and the cover substrate 3 is an Si—Si bonding. In the present embodiment, since the sensor substrate 1, the electrode formation substrate 2, and the cover substrate 3 are formed of Si, which is the same semiconductor material, the linear expansion of the sensor substrate 1, the electrode formation substrate 2, and the cover substrate 3 is performed. It is possible to reduce the influence of stress (residual stress in the sensor substrate 1) resulting from the rate difference on the outputs of the bridge circuits Bx, By, Bz. That is, as compared with the case where the electrode forming substrate 2 and the cover substrate 3 are formed of a material different from that of the sensor substrate 1, variations in sensor characteristics for each product can be reduced.

  Here, since the same metal material is used for each of the connecting metal layers 19 and 29 and the sealing metal layers 18 and 28 to be joined to each other, the joining of the connecting metal layer 19 and the connecting metal layer 29 is performed. The sealing metal layer 18 and the sealing metal layer 28 can be bonded at the same time. Compared to a manufacturing method that involves supplying solder at each bonding location and a reflow process, the manufacturing process can be greatly increased. In addition, the positional accuracy of the electrode forming substrate 2 in the thickness direction of the sensor substrate 1 can be increased. In the configuration example described above, an SOI wafer is used as the sensor wafer on which the sensor substrate 1 is formed. However, this configuration is not essential, and for example, a silicon wafer may be employed instead of the SOI wafer.

  In the acceleration sensor described above, since the pad electrode 25 is formed on the surface of the electrode forming substrate 2 opposite to the surface facing the sensor substrate 1, it can be mounted on the mounting substrate by solder reflow without using an interposer. Is possible. Further, if necessary, a rewiring portion that adjusts the relative positional relationship between the connecting portion of the connecting metal layer 19 and the connecting metal layer 29 and the connecting portion of the connecting metal layer 29 and the through-hole wiring 24 is used. Since it is provided, the degree of freedom in layout such as the size and position of the pad electrode 25 in the electrode forming substrate 2 is increased, and the planar dimension (area of the surface on which the pad electrode 25 is arranged) in the acceleration sensor can be reduced. The rewiring portion can be provided on the connection metal layer 29 of the electrode substrate 2 as well as the connection metal layer 19 of the sensor substrate 1.

  In the above-described embodiment, after the sensor wafer 10, the package wafer 20, and the cap wafer 30 are bonded, a comprehensive inspection of the sensing unit Ds and the circuit unit Dc is performed at the wafer level. Before bonding the package wafer 20 and the cap wafer 30 to 10, a step (FIG. 10D) for inspecting the electrical characteristics of the sensing part Ds and the circuit part Dc formed on the sensor wafer 10 may be added. In addition, in FIG. 10, although the inspection process mentioned above is included between joining and dicing, illustration is abbreviate | omitted.

  By including the inspection process shown in FIG. 10 (d), the sensing unit Ds and the circuit unit Dc are inspected before the package wafer 20 is bonded to the sensor wafer 10, so that the sensing unit Ds and the circuit unit Dc are exposed. The package wafer 20 does not need to be provided with a separate electrode for inspection, which leads to cost reduction. In addition, since the terminals provided on the sensor wafer 10 are formed in a smaller area than the electrodes formed on the package wafer 20, a large number of inspection electrodes can be provided, and various inspections are possible.

It is a figure which shows the process of embodiment. It is a figure which shows the structural example of the probe for a test | inspection in the test | inspection process same as the above. It is a top view of the sensor board | substrate which is a test object same as the above. FIG. 4 is a step sectional view corresponding to a section taken along line AA ′ in FIG. 3. It is a principal part top view which shows the sensing part of the sensor board | substrate used for the same as the above. It is a longitudinal cross-sectional view in the BA 'line cross section of FIG. It is a longitudinal cross-sectional view in the AA 'line cross section of FIG. It is a longitudinal cross-sectional view equivalent to the BB 'line cross section of FIG. It is a circuit diagram same as the above. It is a figure which shows the other process same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor substrate 2 Electrode formation board 10 Sensor wafer 17 Terminal 20 Package wafer 24 Through-hole wiring Dc Circuit part Ds Sensing part

Claims (2)

  A step of forming a sensor substrate having a circuit portion that includes a sensing portion and an integrated circuit and cooperates with the sensing portion on a sensor wafer, and an electrode forming substrate having a through-hole wiring electrically connected to a terminal provided on the sensor substrate The process of forming the package wafer, the process of bonding the sensor wafer and the package wafer and electrically connecting the terminals provided on the sensor substrate and the through-hole wiring, and the electrical characteristics of the sensing unit and the circuit unit after bonding A method for manufacturing a sensor package, comprising: a step of inspecting; and a step of individually cutting and separating a laminate of the sensor substrate and the electrode forming substrate after the inspection.   2. The method of manufacturing a sensor package according to claim 1, further comprising a step of inspecting electrical characteristics of the sensing unit and the circuit unit before bonding the package wafer to the sensor wafer.

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