JP4000167B2 - Manufacturing method of sensor device - Google Patents

Description

The present invention is, for example, a method of manufacturing a sensor device such as an acceleration sensor.

  Conventionally, as shown in FIGS. 11 and 12, an acceleration sensor chip 101 provided with a piezoresistor (not shown) as a sensing unit and a signal processing circuit for processing an output signal of the acceleration sensor chip 101 are formed. The acceleration sensor chip 101 and the IC between the mounted IC chip 102, the mounting substrate 105 having a box shape with one surface open, and the frame portion 111 of the acceleration sensor chip 101 fixed to the inner bottom surface. There has been proposed a sensor device including a lid 106 that closes the one surface of the mounting substrate 105 so as to accommodate the chip 102 (see, for example, Patent Document 1).

  Here, in the sensor device having the configuration shown in FIGS. 11 and 12, the IC chip 102 also serves as a stopper that restricts excessive displacement of the weight portion 112 and the bending portion 113 of the acceleration sensor chip 101, and the acceleration sensor chip. 101 is fixed to the main surface side of the acceleration sensor chip 101 so that a gap of a predetermined interval is formed between the main surface of the acceleration sensor chip 101, and each of the plurality of pads 116 on the main surface side of the acceleration sensor chip 101 is bonded to the bonding wire 108. Are electrically connected to a part of the plurality of pads 121 on the main surface side of the IC chip 102, and the remaining pads 121 of the IC chip 102 are provided on the one surface side of the mounting substrate 105 via bonding wires 109. The terminal pattern 151 is electrically connected.

  In this sensor device, a part of the plurality of pads 121 on the main surface side of the IC chip 102 is electrically connected to the pads 116 of the acceleration sensor chip 101 via the bonding wires 108 and the remaining pads of the IC chip 102. 121 is electrically connected to each terminal pattern 151 provided on the one surface side of the mounting substrate 105 through the bonding wire 109 through the bonding wire 109, and includes the acceleration sensor chip 101 and the IC chip 102. Since the sensor body is housed in a package made up of the mounting substrate 105 and the lid body 106, the mounting height on the circuit board or the like is increased, and a further reduction in the height of the sensor device is desired. It was rare.

Therefore, in order to reduce the height of the sensor device, the acceleration sensor chip 101 and the IC chip 102 are integrated into one chip by forming an IC unit that cooperates with the sensing unit in the frame unit 111 of the acceleration sensor chip 101. Such sensor devices have been conventionally proposed.
JP 2005-169541 A

  In the sensor device described above, after the IC portion is formed on the frame portion 111, an insulating film that functions as a passivation film is formed on the surface of the acceleration sensor chip 101 including the IC portion. In addition, since an insulating film is formed, a tensile stress is applied to the bent portion 113 by the insulating film, and there is a problem that the sensitivity of the sensing unit is lowered. Moreover, since the stress balance of the bending part 113 is bad, there existed a problem that a bending generate | occur | produces in the bending part 113 by a temperature change, and a temperature characteristic deteriorates.

The present invention has been made in view of the above circumstances, it is an object to prevent the characteristics of the piezoresistance is deteriorated by the stress of the insulating film formed on the main surface of the semiconductor substrate The object is to provide a method for manufacturing a sensor device.

According to a first aspect of the present invention, there is provided a sensor unit formed using a semiconductor substrate and having a piezoresistor provided in a movable unit, an IC unit cooperating with the sensor unit, a first sealing metal layer, and a first sealing layer. An electrical connection metal layer is formed, the first sealing metal layer is bonded to a second sealing metal layer provided on the package substrate portion, and the first electrical connection metal layer is and a bonding region portion joined to a second electrical connection metal layer provided on the package substrate portion, Ri mutual layout area Do different of the sensor unit and the IC unit and the bonding area portion, the junction area And a metal layer for sealing in which the bonding surfaces are activated, and a method for manufacturing a sensor device in which the metal layers for electrical connection in which the bonding surfaces are activated are bonded at room temperature. , Forming piezoresistor and IC part on main surface side of semiconductor substrate When providing the surface protective layer comprising a laminated film of a plurality of insulating films, after providing the surface protective layer so as to form an etching stopper layer in the middle as one insulating film constituting the surface protective layer, Etch back thinning the portion formed in the layout region of the sensor portion of the surface protective layer formed on the main surface side of the semiconductor substrate and flattening the portion formed in the layout region of the bonding region portion Etching back to the depth reaching the etching stopper layer from the surface of the surface protective layer, and forming the first sealing metal layer and the first electrical connection metal layer on the surface of the bonding region After the layer forming step, patterning for forming a movable portion in the layout region of the sensor portion is performed.

According to the present invention, the stress generated in the movable part due to the insulating film provided on the main surface side of the semiconductor substrate can be reduced, and the stress is applied to the sensor part in which the piezoresistor is provided in the movable part. In addition, the surface of the bonding region portion with the package substrate portion to be bonded at room temperature can be flattened, and the yield of the bonding process for bonding the package substrate portion at room temperature can be reduced. Can be increased.

Further, according to the present invention, an etching stopper layer formed on the main table surface of the semiconductor substrate, the upper side is formed an insulating film for the etching stopper layer so that is removed by etching, the etching depth constant Thus, the thickness of the insulating film remaining after etching can be controlled to be constant, and variations in stress applied to the movable portion by the insulating film are reduced, so that variations in characteristics of the sensor portion can be suppressed.

According to the first aspect of the present invention, the stress generated in the movable part due to the insulating film provided on the main surface side of the semiconductor substrate can be reduced, and the stress is a sensor in which the piezoresistor is provided in the movable part. it is possible to reduce the influence on the characteristic parts, moreover, the yield of the bonding process can planarize the surface of the bonding area portion of the package substrate unit for room temperature bonding, to the room-temperature bonding the packaging substrate portion Can be increased.

  Hereinafter, a sensor device manufactured using the manufacturing method according to the present invention will be described with reference to FIGS.

  This sensor device is an acceleration sensor divided from the wafer level package structure 100 shown in FIG. 2, and as shown in FIGS. 2 to 4, a sensor unit E1 having a sensing unit, which will be described later, and the sensor unit E1. A sensor main body (sensor substrate) 1 provided with a working IC part E2 and a through-hole wiring 24 electrically connected to the IC part E2 of the sensor main body 1 (see FIG. 2). The first package substrate portion (through-hole wiring forming substrate) 2 bonded to the upper surface side of (c) and the second package bonded to the other surface side (lower surface side in FIG. 3) of the sensor body 1. And a substrate portion (cover substrate) 3. Here, the outer peripheral shapes of the sensor main body 1, the first package substrate unit 2 and the second package substrate unit 3 are rectangular, and the first package substrate unit 2 and the second package substrate unit 3 are rectangular. Are formed in the same outer dimensions as the sensor body 1.

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

  As shown in FIG. 5A, the sensor main body 1 is formed with a sensor portion E1 having the above-described sensing portion in a plan view in a plan view. The sensor portion E1 is surrounded by an IC portion E2, and the IC portion E2 is further described below. The layout of the sensor part E1, the IC part E2, and the joining area part E3 is designed so as to surround the joining area part E3.

  Here, the sensor portion E1 of the sensor body 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 is on one surface side (FIG. 5). On the upper surface side of (b), the frame portion 11 is swingably supported via four flexible strip-shaped bending portions 13. In other words, the sensor part E1 of the sensor body 1 swings to the frame part 11 via the four bending parts 13 in which the weight part 12 arranged inside the frame-like frame part 11 is extended from the weight part 12 in four directions. It is supported freely. Here, the frame portion 11 is formed using the above-described SOI wafer support substrate 10a, insulating layer 10b, and silicon layer 10c. On the other hand, the bending part 13 is formed using the silicon layer 10c in the above-described SOI wafer, and is sufficiently thinner than the frame part 11.

  The weight 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 body 1. And four accompanying portions 12b having a rectangular parallelepiped shape connected to each other. In other words, the weight portion 12 is formed integrally with the core portion 12a and the core portion 12a in which the other end portion of each bending portion 13 whose one end portion is connected to the inner side surface of the frame portion 11 is connected to the outer surface. It has four accompanying parts 12b arranged in the space between the part 12a and the frame part 11. That is, each appendage portion 12b is disposed in a space surrounded by the frame portion 11 and the core portion 12a and the two bent portions 13 and 13 extending in a direction orthogonal to each other when viewed from the one surface side of the sensor substrate 1. In addition, a slit 14 is formed between each of the accompanying portions 12b and the frame portion 11, and the interval between the adjacent accompanying portions 12b with the bending portion 13 interposed therebetween is longer than the width dimension of the bending portion 13. Yes. Here, the core portion 12a is formed using the above-described SOI wafer support substrate 10a, the insulating layer 10b, and the silicon layer 10c, and each accompanying portion 12b is formed using the SOI wafer support substrate 10a. It is. Thus, the surface of each associated portion 12b on the one surface side of the sensor body 1 is separated from the plane including the surface of the core portion 12a to the other surface side of the sensor body 1 (the lower surface side in FIG. 5B). Is located. Note that the above-described frame portion 11, weight portion 12, and each bending portion 13 of the sensor body 1 may be formed using a lithography technique and an etching technique.

  By the way, as shown in the lower right of each of FIGS. 5A and 5B, one direction along one side of the frame portion 11 in a plane parallel to the one surface of the sensor body 1 is the positive direction of the x axis, If one direction along the side perpendicular to the one side is defined as the positive direction of the y-axis and one direction of the thickness direction of the sensor substrate 1 is defined as the positive direction of the z-axis, the weight portion 12 is extended in the x-axis direction. It is supported by the frame portion 11 via a pair of bending portions 13, 13 sandwiching the core portion 12a and a pair of bending portions 13, 13 extending in the y-axis direction and sandwiching the core portion 12a. Will be. In the orthogonal coordinates defined by the three axes of the above-described x axis, y axis, and z axis, the center position of the weight portion 12 on the surface of the portion of the sensor substrate 1 formed by the silicon layer 10c is the origin.

  The bending portion 13 (the bending portion 13 on the right side of FIG. 5A) extended from the core portion 12a of the weight portion 12 in the positive direction of the x-axis is a pair of piezoresistors Rx2 and Rx4 in the vicinity of the core portion 12a. Is formed, and one piezoresistor Rz2 is formed in the vicinity of the frame portion 11. On the other hand, the bending portion 13 (the bending portion 13 on the left side of FIG. 5A) extended from the core portion 12a of the weight portion 12 in the negative direction of the x-axis is a pair of piezoresistors Rx1 in the vicinity of the core portion 12a. , Rx3 are formed, and one piezoresistor Rz3 is formed in the vicinity of the frame portion 11. Here, the four piezoresistors Rx1, Rx2, Rx3, and Rx4 formed in the vicinity of the core portion 12a are formed to detect acceleration in the x-axis direction, and the planar shape is an elongated rectangular shape. 7 is formed so that the longitudinal direction thereof coincides with the longitudinal direction of the bent portion 13 (the direction connecting the frame portion 11 and the core portion 12a), and the sensor is configured to constitute the left bridge circuit Bx in FIG. They are connected by wiring (diffusion layer wiring, metal wiring, etc.) (not shown) formed on the substrate 1. 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. 5A) extended from the core portion 12a of the weight portion 12 in the positive direction of the y-axis is a pair of piezoresistors Ry1, in the vicinity of the core portion 12a. Ry3 is formed, and one piezoresistor Rz1 is formed in the vicinity of the frame portion 11. On the other hand, the bending portion 13 (the lower bending portion 13 in FIG. 5A) extended from the core portion 12a of the weight portion 12 in the negative direction of the y-axis is a pair of piezoresistors Ry2 in the vicinity of the core portion 12a. , Ry4 are formed, and one piezoresistor Rz4 is formed at the end on the frame part 11 side. Here, the four piezoresistors Ry1, Ry2, Ry3, and Ry4 formed in the vicinity of the core portion 12a are formed to detect acceleration in the y-axis direction, and the planar shape is an elongated rectangular shape. Wiring (diffuse layer wiring, metal not shown) formed on the sensor substrate 1 so that the longitudinal direction coincides with the longitudinal direction of the flexure 13 and forms the central bridge circuit By in FIG. Connected by wiring). Note that the piezoresistors Ry1 to Ry4 are formed in a stress concentration region where stress is concentrated in the flexure 13 when acceleration in the y-axis direction is applied.

Further, the four piezoresistors Rz1, Rz2, Rz3, and Rz4 formed in the vicinity of the frame portion 11 are formed to detect acceleration in the z-axis direction, and constitute the right bridge circuit Bz in FIG. wiring (not shown) are formed on the sensor body 1 to (diffusion layer wirings and metal wirings) are connected by. 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 operation | movement of the sensor part E1 of the sensor main body 1 is demonstrated.

  Now, assuming that acceleration is applied to the sensor body 1 in the positive x-axis direction while no acceleration is applied to the sensor body 1, the frame portion 11 is caused by the inertial force of the weight 12 acting in the negative x-axis direction. Accordingly, the weight 12 is displaced, and as a result, the bending portions 13 and 13 whose longitudinal direction is the x-axis direction are bent, and the resistance values of the piezoresistors Rx1 to Rx4 formed in the bending portions 13 and 13 are changed. Will do. In this case, the piezoresistors Rx1 and Rx3 are subjected to tensile stress, and the piezoresistors Rx2 and Rx4 are subjected to compressive stress. In general, a piezoresistor has a characteristic that a resistance value (resistivity) increases when subjected to a tensile stress, and a resistance value (resistivity) decreases when subjected to a compressive stress. Therefore, the piezoresistors Rx1 and Rx3 are resistant. The value increases, and the resistance values of the piezoresistors Rx2 and Rx4 decrease. Therefore, if a constant DC voltage is applied from the external power source between the pair of input terminals VDD and GND shown in FIG. 7, 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. 7 changes according to the magnitude of the acceleration in the y-axis direction, and the z-axis When the acceleration in the direction is applied, the potential difference between the output terminals Z1 and Z2 of the right bridge circuit Bz shown in FIG. 7 changes according to the magnitude of the acceleration in the z-axis direction. Thus, the sensor unit E1 of the sensor body 1 described above detects changes in the output voltages of the respective bridge circuits Bx to Bz, so that the x-axis direction, the y-axis direction, and the z-axis direction that act on the sensor unit E1 are detected. Each acceleration can be detected. In this embodiment, the weight part 12 and each bending part 13 comprise the movable part 15, and each piezoresistor Rx1-Rx4, Ry1-Ry4, Rz1-Rz4 comprises the sensing part in the sensor main body 1. FIG. ing.

  Further, the IC part E2 of the sensor body 1 is an integrated circuit (CMOS IC) using CMOS, and an integrated circuit that cooperates with the piezo resistors Rx1 to Rx4, Ry1 to Ry4, and Rz1 to Rz4 that are the sensing parts is formed. Has been. Here, the integrated circuit of the IC unit E2 includes a signal processing circuit that performs signal processing such as amplification, offset adjustment, and temperature compensation on the output signals of the bridge circuits Bx, By, and Bz, and a signal processing circuit. An EEPROM or the like that stores data used in is integrated.

By the way, the sensor main body 1 has silicon on the surface side of a part corresponding to a part of the sensor part E1 (core part 12a, each bending part 13, the frame part 11) and the IC part E2 and the joining area part E3 in the silicon layer 10c. A surface insulating film 16 made of a laminated film of a first insulating film made of a silicon oxide film on the layer 10c and a second insulating film made of a silicon nitride film on the first insulating film is formed. Here, IC portion E2 of the sensor body 1 is aimed at reduction of the occupied area of the IC portion E2 of definitive to sensor body 1 by using a multilayer wiring technique on the surface insulating film 16, at least 1 A third insulating film made of an interlayer insulating film (silicon oxide film), and a fourth insulating film made of a passivation film (a laminated film of a silicon oxide film and a silicon nitride film) on the third insulating film. are multilayer structures 41 including the formation, are to expose the pad 42 of the multiple by removing appropriate portions of the passivation film.

  The sensor body 1 is joined to a plurality of first electrical connection metal layers 19 for electrically connecting the sensing section and the plurality of through-hole wirings 24 of the first package substrate section 2 described above. Is formed on the surface insulating film 16 in the area E3, and each pad 42 is electrically connected to the first electrical connection metal layer 19 via a lead wire 43 made of a metal material (for example, Au). (See FIG. 6). Here, in this embodiment, the material of the lead-out wiring 43 and the material of the first electrical connection metal layer 19 are the same, and the lead-out wiring 43 and the first electrical connection metal layer 19 are formed continuously. Has been. The plurality of pads 42 formed in the IC part E2 are electrically connected to the sensing part through a signal processing circuit and electrically connected to the sensing part without passing through the signal processing circuit. In any case, in any case, the through-hole wiring 24 of the first package substrate portion 2 and the sensing portion are electrically connected.

  Here, in the bonding region E3 of the sensor main body 1, a frame-shaped (rectangular frame-shaped) first sealing metal layer 18 is formed on the surface insulating film 16, and the plurality of first layers described above. The electrical connection metal layer 19 is formed on the surface insulating film 16 on the inner side of the first sealing metal layer 18. In short, in the sensor body 1, the first sealing metal layer 18 and the respective electrical connection metal layers 19 are formed on the same level surface with the silicon nitride film of the surface insulating film 16 as a base layer. Here, the plurality of first electrical connection metal layers 19 are arranged apart from each other in the circumferential direction of the bonding region E3.

  In the first sealing metal layer 18 and the first electrical connection metal layer 19, an adhesion improving Ti film is interposed between the bonding Au film and the surface insulating film 16. In other words, the first sealing metal layer 18 and the first electrical connection metal layer 19 are a laminated film of a Ti film formed on the surface insulating film 16 and an Au film formed on the Ti film. It is comprised by. In short, since the first electrical connection metal layer 19 and the first sealing metal layer 18 are formed of the same metal material, the first electrical connection metal layer 19 and the first sealing metal layer 19 are formed. The metal layer 18 can be formed at the same time, and the first electrical connection metal layer 19 and the first sealing metal layer 18 can be formed to have substantially the same thickness. Note that the first sealing metal layer 18 and the first electrical connection metal layer 19 have a Ti film thickness of 15 to 50 nm and an Au film thickness of 500 nm. Is an example and is not particularly limited. Here, the material of each Au film is not limited to pure gold, and may be added with impurities. Further, in this embodiment, a Ti film is interposed as an adhesion improving layer for adhesion between each Au film and the surface insulating film 16, but the material of the adhesion layer is not limited to Ti, for example, Cr, Nb, Zr, TiN, TaN, etc. may be used.

  As shown in FIG. 8 and FIG. 9, the first package substrate portion 2 includes a weight portion 12 of the sensor substrate 1 and each bending portion 13 on the surface of the sensor main body 1 (the lower surface side in FIG. 3). The displacement space forming concave portion 21 that secures the displacement space of the movable portion 15 is formed, and a plurality of through holes 22 penetrating in the thickness direction are formed in the peripheral portion of the displacement space forming concave portion 21. An insulating film 23 made of a thermal insulating film (silicon oxide film) is formed across both surfaces in the direction and the inner surface of the through hole 22, and part of the insulating film 23 is formed between the through hole wiring 24 and the inner surface of the through hole 22. Is intervening. Here, the first package substrate portion 2 has the opening of the displacement space forming recess 21 so that the sensor portion E1 and the IC portion E2 of the sensor body 1 are within the projection area of the opening surface of the displacement space forming recess 21. The area is increased, and the multilayer structure portion 41 of the IC portion E2 is arranged in the displacement space forming recess 21 (see FIGS. 3 and 4). The plurality of through-hole wirings 24 of the first package substrate unit 2 are formed apart from each other in the circumferential direction of the first package substrate unit 2. Moreover, although Cu is adopted as the material of the through-hole wiring 24, it is not limited to Cu, and for example, Ni may be adopted.

  In addition, the first package substrate portion 2 has a plurality of second electrical connections electrically connected to the respective through-hole wirings 24 on the peripheral portion of the displacement space forming recess 21 on the surface on the sensor body 1 side. A metal layer 29 is formed. Further, the first package substrate 2 has a frame-shaped (rectangular frame-shaped) second sealing metal layer 28 formed over the entire circumference of the peripheral portion of the surface on the sensor body 1 side. The plurality of second electrical connection metal layers 29 are arranged inside the second sealing metal layer 28 (where the second sealing metal layer 28 and each electrical connection metal The layer 29 is formed on the same level surface of the insulating film 23). Here, the second electrical connection metal layer 29 has an elongated rectangular outer peripheral shape, one end portion in the longitudinal direction is joined to the through-hole wiring 24, and the other end side portion is the sensor body 1. The first electrical connection metal layer 19 is joined and electrically connected. In short, the positions of the through-hole wiring 24 and the first electrical connection metal layer 19 corresponding to the through-hole wiring 24 are shifted in the circumferential direction of the first package substrate portion 2, so that the second electrical connection The metal layer 29 is arranged so that the longitudinal direction thereof coincides with the circumferential direction of the second sealing metal layer 28 and straddles the through-hole wiring 24 and the first electrical connection metal layer 19.

  In addition, the second sealing metal layer 28 and the second electrical connection metal layer 29 have an adhesion improving Ti film interposed between the bonding Au film and the insulating film 23. In other words, the second sealing metal layer 28 and the second electrical 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. It is configured. In short, since the second electrical connection metal layer 29 and the second sealing metal layer 28 are formed of the same metal material, the second electrical connection metal layer 29 and the second sealing metal layer 28 are formed. The metal layer 28 can be formed at the same time, and the second electrical connection metal layer 29 and the second sealing metal layer 28 can be formed to have substantially the same thickness. The second sealing metal layer 28 and the second electrical connection metal layer 29 have a Ti film thickness of 15 to 50 nm and an Au film thickness of 500 nm. Is an example and is not particularly limited. Here, the material of each Au film is not limited to pure gold, and may be added with impurities. Further, in this embodiment, a Ti film is interposed as an adhesion improving layer for adhesion between each Au film and the surface insulating film 16, but the material of the adhesion layer is not limited to Ti, for example, Cr, Nb, Zr, TiN, TaN, etc. may be used.

  A plurality of external connection electrodes 25 electrically connected to the respective through-hole wirings 24 are formed on the surface of the first package substrate 2 opposite to the sensor body 1 side. The outer peripheral shape of each external connection electrode 25 is rectangular.

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

  By the way, the sensor body 1 and the first package substrate 2 described above are bonded to the first sealing metal layer 18 and the second sealing metal layer 28 and have the first electrical connection. The metal layer 19 for electrical connection and the second metal layer 29 for electrical connection are joined, and the sensor body 1 and the second package substrate part 3 are joined at the peripheral portions of the opposing surfaces. Here, in manufacturing the acceleration sensor of the present embodiment, as shown in FIG. 2, a sensor wafer 10 in which a plurality of sensor substrates 1 are formed on an SOI wafer, and a first package substrate portion 2 on a first silicon wafer. A plurality of first package wafers 20 and a second package wafer 30 having a plurality of second package substrate portions 3 formed on a second silicon wafer are bonded at room temperature to a wafer level package structure. 100 is formed and then divided into individual acceleration sensors by a dividing process (dicing process) for dividing into individual acceleration sensors (FIG. 2 (c) shows the wafer level package structure shown in FIG. 2 (a). It is a schematic sectional view of a portion surrounded by a circle A in the body 100). Therefore, the first package substrate unit 2 and the second package substrate unit 3 have the same size (outer size) as the sensor body 1, and a small chip size package can be realized. In the present embodiment, the bonding region E3 of the sensor body 1, the first package substrate 2 and the second package substrate 3 form a package, and the weight 12 in the package. The movable part 15 constituted by the respective bending parts 13 can be displaced.

  Here, in the present embodiment, a room temperature bonding method is employed as a bonding method between the sensor body 1 and the first package substrate unit 2 and the second package substrate unit 3. In the following, the steps characteristic of the method of manufacturing the acceleration sensor according to the present embodiment will be described with reference to FIG. 1. FIGS. 1A to 1F correspond to the AA ′ cross section of FIG. The cross section of the part to show is shown.

  First, diffusion layer wiring for forming piezoresistors Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4, bridge circuits Bx, By, and Bz and an IC portion E2 are provided on the main surface side of the SOI wafer (the surface side of the silicon layer 10c). The structure shown in FIG. 1A is obtained by forming using a CMOS process technology or the like. Here, at the stage where the step of exposing each pad 42 of the IC portion E2 is completed, the multilayer structure portion 41 is formed on the entire surface of the surface insulating film 16, and the sensor portion E1 and the bonding portion of the multilayer structure portion 41 are joined. The metal wiring is not provided in the part formed in the site | part corresponding to the use area | region part E3. In the present embodiment, the surface protective layer 44 is constituted by a multilayer insulating film composed of the surface insulating film 16 and the multilayer structure portion 41.

  After the step of exposing each of the pads 42 is finished, the resist layer patterned so as to expose the portions formed in the portions corresponding to the sensor portion E1 and the bonding region portion E3 in the surface protective layer 44, respectively. (Not shown) is formed on the main surface side of the SOI wafer, and the resist layer is used as an etching mask, and is formed in the bonding region portion E3 of the sensor body 1 with the package substrate portion 2 in the multilayer insulating film. The structure shown in FIG. 1B is obtained by performing a flattening step of flattening the surface of the bonding region E3 by etching back the portion that has been formed. By this etching process, a part (multilayer structure part) of the surface protection layer 44 made of a multilayer insulating film formed in a part constituting the sensor part E1 (that is, a part constituting the frame part 11 and the movable part 15). 41) is removed, so that only the surface insulating film 16 is formed, and the thickness of the insulating film formed on the movable portion 15 is adjusted to a thinner dimension, so that the stress of the insulating film formed on the upper surface of the movable portion 15 is adjusted. As a result, the bending generated in the movable portion 15 is reduced. Etch back is performed by wet etching, and the second insulating film made of the silicon nitride film of the surface insulating film 16 is used as an etching stopper layer.

  After the planarization step, a metal layer forming step for forming the first sealing metal layer 18 and the first electrical connection metal layer on the surface of the bonding region E3 is performed (in this embodiment, In the metal layer forming step, the lead-out wiring 43 is also formed), and then on the main surface side of the SOI wafer, the frame portion 11 in the surface insulating film 16 described above, the core portion 12a of the weight portion 12, the respective bent portions 13, A resist layer (not shown) patterned so as to cover portions corresponding to the IC portion E2 and the bonding region portion E3 and to expose other portions is formed, and the surface insulating film 16 is formed using the resist layer as an etching mask. A surface-side patterning step of patterning the surface insulating film 16 by etching the exposed portion of the substrate and etching the SOI wafer to a depth reaching the insulating layer 10b from the main surface side. By Ukoto to obtain a structure shown in Figure 1 (c). Here, in the metal layer forming step, the first sealing metal layer 18, the first connection metal layer 19, and the lead-out wiring 43 are formed on the main surface side of the SOI wafer by a thin film forming technique such as sputtering and lithography. It is formed using technology and etching technology. Further, in the surface side patterning step, the insulating layer 10b is used as an etching stopper layer, and by performing the surface side patterning step, the silicon layer 10c in the SOI wafer has a portion corresponding to the frame portion 11 and a core portion. A portion corresponding to 12a, a portion corresponding to each of the bending portions 13, a portion corresponding to the IC portion E2, and a portion corresponding to the joining region portion E3 remain. In the etching in this surface side patterning step, for example, dry etching may be performed using an inductively coupled plasma (ICP) type dry etching apparatus. As an etching condition, the insulating layer 10b functions as an etching stopper. Set appropriate conditions.

  After the surface-side patterning step described above, in the silicon oxide film 10d laminated on the support substrate 10a on the back side of the SOI wafer, the portion corresponding to the frame portion 11, the portion corresponding to the core portion 12a, and each associated portion 12b Forming a resist layer (not shown) patterned so as to cover the corresponding part, the part corresponding to the IC part E2 and the part corresponding to the bonding area part E3 and to expose the other part; Using the resist layer as an etching mask, the exposed portion of the silicon oxide film 10d is etched to pattern the silicon oxide film 10d, and after removing the resist layer, the silicon wafer 10d as an etching mask and the SOI wafer from the back side. Back side patterning process for dry etching substantially perpendicularly to a depth reaching the insulating layer 10b By performing to obtain a structure shown in FIG. 1 (d). In this back side patterning step, the insulating layer 10b is used as an etching stopper layer, and by performing the back side patterning step, the support substrate 10a in the SOI wafer has a portion corresponding to the frame portion 11 and a core portion 12a. , A portion corresponding to each of the accompanying portions 12b, a portion corresponding to the IC portion E2, and a portion corresponding to the joining region portion E3 remain. For example, the above-described ICP type dry etching apparatus may be used as the etching apparatus in the back surface side patterning step, and the etching conditions are set such that the insulating layer 10b functions as an etching stopper.

  After the back side patterning step, an unnecessary portion of the insulating layer 10b is left with a portion corresponding to the frame portion 11, a portion corresponding to the core portion 12a, a portion corresponding to the IC portion E2, and a portion corresponding to the bonding region portion E3. The sensor wafer 10 having the structure shown in FIG. 1E is obtained by performing a separation step of forming the frame part 11, each bending part 13, and the weight part 12 by etching away the material by wet etching. In this separation step, the silicon oxide film 10d on the back side of the SOI wafer is also removed by etching.

  After the above-described separation step, a first bonding step is performed in which the sensor wafer 10 and the second package wafer 30 are directly bonded by a room temperature bonding method, and then the sensor wafer 10 and the first package wafer 20 are sealed. A wafer level package structure 100 having a structure shown in FIG. 1 (f) is obtained by performing a bonding step of directly bonding the metal layers 18 and 28 and the metal layers 19 and 29 for electrical connection. In short, in the first bonding step, the sensor wafer 10 and the second package wafer 30 are bonded by Si-Si room temperature bonding, and in the second bonding step, the sensor wafer 10 and the first package wafer 20 are sealed. The metal layers 18 and 28 for electrical connection and the metal layers 19 and 29 for electrical connection are bonded by metal-metal (here, Au—Au) room temperature bonding. In the normal temperature bonding method, the bonding surfaces are contacted with each other after the bonding surfaces are cleaned and activated by irradiating the bonding surfaces with argon plasma, ion beam or atomic beam in vacuum before bonding. And bond directly at room temperature. Here, in the second bonding step, the first sealing metal layer 18 and the second sealing metal layer 28 are directly applied by applying an appropriate load at room temperature by the above-described room temperature bonding method. Simultaneously with the bonding, the first electrical connection metal layer 19 and the second electrical connection metal layer 29 are directly bonded.

  By the way, in the method for manufacturing the acceleration sensor according to the present embodiment, the entire process up to the end of the second bonding process described above is performed at the wafer level for each of the sensor body 1 and each of the package substrate portions 2 and 3. Since the wafer level package structure 100 (see FIG. 5) including a plurality of the wafer level package structure 100 is formed, and the dividing process (dicing process) for dividing the wafer level package structure 100 into the individual acceleration sensors is performed. The size of each of the package substrate portions 2 and 3 can be matched with the size of the sensor body 1 and the mass productivity can be improved.

According to the manufacturing method of an acceleration sensor of the present embodiment described above, the multilayered insulating film (surface protective layer 44) is formed over the entire surface on the main table surface side of the SOI wafer which is a semiconductor substrate, formed in the movable portion 15 surface protective layer 44 (an insulating film) by edge quenching and because by removing a portion of the surface protective layer 44 (multilayer structure portion 41), the insulating film by adjusting the thickness of the surface protective layer 44 stress Can be reduced. And Thus, since the deflection generated Rica pivot portion 15 by the stress of the insulating film formed on the movable portion 15 is reduced, it is possible to suppress the influence of the stress applied to the characteristics of the sensor portion E1 . When the surface protection layer 44 formed on the movable portion 15 is etched, the second insulating film made of the silicon nitride film of the surface insulating film 16 is used as an etching stopper layer, and is above the etching stopper layer. Since the formed insulating film is removed by etching, the etching depth can be kept constant, and the thickness of the insulating film remaining after etching can be controlled to be constant, and the variation in stress applied to the movable part by the insulating film is reduced. Thus, variations in the characteristics of the sensor unit E1 can be suppressed .

  Further, the multilayer insulating film formed on the main surface side of the SOI wafer is bonded by etching back the portion formed in the bonding region E3 with the first package substrate 2 in the sensor body 1. Since the first sealing metal layer 18 and the first electrical connection metal layer 19 are formed on the surface of the bonding region E3 after the surface of the region for use E3 is planarized, the first The sealing metal layer 18 and the first electrical connection metal layer 19 can be formed on the same level surface with the same thickness, and the surface of the first sealing metal layer 18 and the first electrical connection metal layer 19 can be formed. The flatness of the surface of the connection metal layer 19 can be improved, and the sealing metal layers 18 and 28 and the electrical connection metal layers 19 and 29 between the sensor body 1 and the first package substrate portion 2 can be connected to each other. Yield of the second bonding process for direct bonding Since it is possible to increase, thereby improving the manufacturing yield.

  Further, in the wafer level package structure 100 of the present embodiment, the sensor body 1, the first package substrate unit 2, and the second package substrate unit 3 constitute an acceleration sensor that is a sensor device including a package. Therefore, the height of the acceleration sensor including the package can be reduced as compared with the conventional acceleration sensor shown in FIGS. 11 and 12, and the sensor wafer 10 and the package wafers 20 and 30 are directly bonded. Since a low-temperature process such as a room-temperature bonding method can be adopted as a method, the process temperature can be lowered and the dielectric breakdown of the IC part E2 at the time of manufacture can be prevented. Here, in the case where the sensor wafer 10, the first package wafer 20 and the second package wafer 30 are bonded by room temperature bonding, the IC portion E2 is formed in the first bonding process and the second bonding process described above. Since stress due to heat or an electric field is not applied, the dielectric breakdown of the IC portion E2 can be more reliably prevented.

  In the wafer level package structure 100 of the present embodiment, the sensor wafer 10 is formed using an SOI wafer, and the first package wafer 20 and the second package wafer 30 are each formed using a silicon wafer. The stress generated in the bent portion 13 due to the difference in linear expansion coefficient between the sensor wafer 10 and each package wafer 20 and 30 can be reduced, and the stress due to the difference in linear expansion coefficient is output from the bridge circuits Bx, By, Bz. Since the influence on the signal can be reduced, it becomes possible to reduce the temperature dependence of the output characteristics of the sensing unit provided in the sensor unit E1. In the present embodiment, the sensor wafer 10 is formed by processing an SOI wafer, and the SOI wafer constitutes the first semiconductor wafer. However, the first semiconductor wafer is not limited to the SOI wafer, for example, A silicon wafer may be used. In the present embodiment, as described above, the first package wafer 20 is formed by processing the first silicon wafer, and the second package wafer 30 is formed by processing the second silicon wafer. The first silicon wafer constitutes the second semiconductor wafer, and the second silicon wafer constitutes the third semiconductor wafer. In addition, although the first to third semiconductor wafers have a common wafer material of silicon, the wafer materials of the first to third semiconductor wafers are not limited to silicon but may be other semiconductors.

Incidentally, although in the embodiment described above has exemplified the acceleration sensor of piezoresistive type as the sensor device, the sensor device is not limited to the acceleration sensor of the piezoresistive type, depending on the structure of the sensor body, the substrate portion for the second package The sensor device can be constituted by the sensor body and the first package substrate portion without using them. Also, although constituting a movable portion 15 in the bending portion 13 and the heavy Ri portion 12, the movable portion is constituted by the diaphragm in the case of the pressure sensor diaphragm structure.

(A)-(f) is sectional drawing which showed the main processes which manufacture a sensor apparatus using the manufacturing method which concerns on this invention. The wafer level package structure manufactured using the manufacturing method same as the above is shown, (a) is a schematic plan view, (b) is a schematic side view, and (c) is a schematic cross-sectional view of the main part. It is a schematic sectional drawing which shows the sensor apparatus manufactured by the manufacturing method same as the above. The sensor apparatus manufactured with the manufacturing method same as the above is shown, (a) is a principal part schematic sectional drawing, (b) is another principal part schematic sectional drawing. The sensor main body manufactured by the manufacturing method same as the above is shown, (a) is a schematic plan view, and (b) is a schematic cross-sectional view. It is a principal part schematic sectional drawing of the sensor main body manufactured by the manufacturing method same as the above. It is a circuit diagram of the sensor part manufactured by the manufacturing method same as the above. The 1st board | substrate part for a package in the sensor main body manufactured by the manufacturing method same as the above is shown, (a) is a schematic plan view, (b) is A-A 'schematic sectional drawing of (a). It is a bottom view of the 1st substrate part for packages in the sensor main part manufactured by the manufacturing method same as the above. The 2nd board | substrate part for packages in the sensor main body manufactured by the manufacturing method same as the above is shown, (a) is a schematic plan view, (b) is a schematic sectional drawing. It is a schematic sectional drawing of the sensor apparatus of a prior art example. It is a schematic exploded perspective view of a sensor apparatus same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor main body 11 Frame part 12 Weight part 13 Deflection part 15 Movable part 16 Surface insulating film 41 Multilayer structure part 44 Surface protective layer E2 IC part

Claims (2)

A sensor unit formed using a semiconductor substrate and provided with a piezoresistor on the movable unit, an IC unit cooperating with the sensor unit, a first metal layer for sealing, and a first metal layer for electrical connection are formed. The first sealing metal layer is bonded to the second sealing metal layer provided on the package substrate portion, and the first electrical connection metal layer is provided on the package substrate portion. and a bonding region portion joined to a second electrical connection metal layer, another of the layout area of the bonding area portion and the sensor portion and the IC portion Ri is Do different in bonding area portion, the bonding surfaces to each other Is a method of manufacturing a sensor device in which metal layers for sealing whose metal surfaces are activated and metal layers for electrical connections whose respective bonding surfaces are activated are bonded at room temperature, respectively , on the main surface side of the semiconductor substrate Insulating films with the formation of piezoresistors and IC parts When providing the surface protective layer made of a laminated film, after providing the surface protective layer so as to form an etching stopper layer as one insulating film constituting the surface protective layer, the main surface side of the semiconductor substrate Etch back for thinning a portion formed in the layout region of the sensor portion of the surface protective layer formed on the surface and an etch back for flattening a portion formed in the layout region of the bonding region portion. A metal layer forming step for forming the first sealing metal layer and the first electrical connection metal layer on the surface of the bonding region was performed from the surface of the protective layer to the depth reaching the etching stopper layer . Thereafter, patterning for forming a movable portion in the layout region of the sensor portion is performed.   2. The method of manufacturing a sensor device according to claim 1, wherein a silicon nitride film is formed as the etching stopper layer.

Images