JP2010225746A - Sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable sensor device by forming a sensor board by a simple manufacturing process, and by firmly sealing the sensor board and a wiring board by room-temperature activated bonding of semiconductors. <P>SOLUTION: A sensor device comprises: a sensor board 1 having a sensing section; and a wiring board 2 sealed on one surface of the sensor board 1. In the sensor device, impurities are added into part of the one surface of the sensor board 1 to turn it into a first high concentration diffusion region 19, which is electrically connected to the sensing section, and impurities are added into part of the surface of the wiring board 2 on the sensor board 1 side to turn it into a second high concentration diffusion region 29, which is electrically connected to an external electrode 25 provided outside. The sensor board 1 and the wiring board 2 are sealed by room-temperature activated bonding of the first high concentration diffusion region 19 and the second high concentration diffusion region 29. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sensor device such as an acceleration sensor device or a gyro sensor device.

  In recent years, as a sensor device having a chip size package (CSP), a sensor device formed using a wafer level packaging technique has been researched and developed in various places (for example, refer to Patent Document 1).

  As shown in FIG. 11, the sensor device described in Patent Document 1 is formed using a first semiconductor substrate, and includes a sensing unit and a sensor substrate 1 that is electrically connected to the sensing unit, A through-hole wiring forming substrate 2 formed using a second semiconductor substrate and having a through-hole wiring 24 electrically connected to the metal wiring 17 and sealed to one surface side of the sensor substrate 1. Yes.

  Here, in the sensor substrate 1, the first sealing bonding metal layer 18 is formed over the entire circumference of the peripheral portion on the one surface, and the inner side of the first sealing connection metal layer 18 is formed. A first connecting bonding metal layer 19 electrically connected to the metal wiring 17 is formed, and the through-hole wiring forming substrate 2 is connected to the second sealing over the entire circumference of the peripheral portion on the surface on the sensor substrate 1 side. A stop bonding metal layer 28 is formed, and a second connection bonding metal layer 29 electrically connected to the through-hole wiring 24 is formed inside the second sealing bonding metal layer 28. Yes.

  Then, the sensor substrate 1 and the through-hole wiring forming substrate 2 are each formed by joining the first sealing bonding metal layer 18 and the second sealing bonding metal layer 28, whose bonding surfaces are activated, at room temperature activation bonding. At the same time, the first connection bonding metal layer 19 and the second connection bonding metal layer 29 in which the respective bonding surfaces are activated are integrally joined by normal temperature activation bonding.

  Therefore, in the sensor device described in Patent Document 1, the sensor substrate 1 and the through-hole wiring formation substrate 2 can be easily bonded at room temperature, and the bonding reliability between the sensor substrate 1 and the through-hole wiring formation substrate 2 can be easily achieved. It is said that it can improve sex.

JP2007-173757

  However, in the above-described sensor device, it is necessary to form the first connection bonding metal layer 19 on the sensor substrate 1, and the second connection bonding metal layer 29 is formed on the through-hole wiring formation substrate 2. There was a need to do. Therefore, a step of manufacturing the first connection bonding metal layer 19 and the second connection bonding metal layer 29, a step of arranging the first connection bonding metal layer 19 on the sensor substrate 1, and a second connection There is a problem that a process of arranging the bonding metal layer 29 on the through-hole wiring forming substrate 2 is necessary and the manufacturing process is complicated. Further, the normal temperature activated bonding between the first connecting bonding metal layer 19 and the second connecting bonding metal layer 29 has a problem that the bonding strength is weak because the bonding is between conductive materials.

  The present invention has been invented in view of the above-described background art, and the problem is that the above-described complicated manufacturing can be performed without using the first connection bonding metal layer 19 and the second connection bonding metal layer 29. By manufacturing a sensor device by a simple manufacturing process without using a process, it is difficult to generate defects that may occur due to a complicated manufacturing process, and use a room temperature activated bonding between conductive materials. It is to provide a highly reliable sensor device by manufacturing the sensor device without any problems.

  In order to solve the above-mentioned problem, in the invention according to claim 1 of the present application, one surface of a sensor substrate formed by using a first semiconductor substrate and a sensor substrate having a sensing portion and a second semiconductor substrate. In a sensor device comprising: a wiring substrate sealed to a first substrate, a part of the one surface of the sensor substrate is added with an impurity to form a first high concentration diffusion region, and the first high concentration diffusion region is a sensing unit. A part of the surface of the wiring substrate on the sensor substrate side is doped to form a second high concentration diffusion region, and the second high concentration diffusion region is electrically connected to an external electrode provided outside. The sensor substrate and the wiring board are sealed by the first high-concentration diffusion region and the second high-concentration diffusion region being joined at normal temperature activation.

  Further, in the invention according to claim 2 of the present application, in the sensor device according to claim 1, a part of the surface of the wiring board on the sensor board side protrudes as the second high concentration diffusion region, Outside the second high-concentration diffusion region, a sealing semiconductor layer is formed at substantially the same height as the second high-concentration diffusion region over the entire circumference of the peripheral portion on the surface of the wiring board. The substrate and the wiring board are formed by joining the first high concentration diffusion region and the second high concentration diffusion region at room temperature activation bonding, and the sealing bonding portion and the sealing over the entire circumference of the peripheral portion on the surface of the sensor substrate. It is characterized in that the sealing semiconductor layer is sealed by normal temperature activation bonding.

  According to a third aspect of the present invention, in the sensor device according to the second aspect, the second semiconductor substrate on which the wiring board is formed includes a substrate layer, an oxide layer, and an active layer doped with impurities. A wiring board is formed by patterning an active layer so as to include a second high concentration diffusion region and a sealing semiconductor layer.

  According to a fourth aspect of the present invention, in the sensor device according to the third aspect, a through hole is formed in the substrate layer and the oxide layer of the wiring substrate so that the second high concentration diffusion region is exposed. A thin film conductive film is formed on the inner peripheral surface of the electrode, and the external electrode and the second high concentration diffusion region are electrically connected by the thin film conductive film.

  Further, in the invention according to claim 5 of the present application, in the sensor device according to any one of claims 2 to 4, the first high-concentration diffusion region and the sealing joint portion are formed on the one surface of the sensor substrate. An insulating film is formed between the two.

  In the sensor device according to the first aspect of the present invention, a part of one surface of the sensor substrate formed using the first semiconductor substrate is added with impurities to form the first high concentration diffusion region, and the second semiconductor Since a part of the surface of the wiring substrate formed using the substrate is added as an impurity to form a second high concentration diffusion region, and the first high concentration diffusion region and the second high concentration diffusion region are joined at normal temperature activation, The sensor device can be manufactured by a simple manufacturing process, and the first high-concentration diffusion region and the second high-concentration diffusion region can be firmly bonded by room-temperature activated bonding between semiconductors. A high sensor device can be provided.

  In the sensor device according to the second aspect of the present invention, in particular, a part of the surface of the wiring substrate on the sensor substrate side is formed to protrude as the second high concentration diffusion region, and the second high concentration Outside the diffusion region, a sealing semiconductor layer is formed at substantially the same height as the second high-concentration diffusion region over the entire circumference of the peripheral portion on the surface of the wiring substrate. Means that the first high-concentration diffusion region and the second high-concentration diffusion region are joined at normal temperature activation, and the sealing junction region and the sealing semiconductor layer over the entire circumference of the peripheral portion on the surface of the sensor substrate Are sealed by normal temperature activation bonding, the first high-concentration diffusion region and the sealing bonding portion in the sensor substrate may be formed with a smooth surface, and the sensor substrate is formed by a simple manufacturing process. Can with sensor board and wiring board Because it is firmly sealed by the room temperature activation bonding of semiconductor together, it is possible to provide a highly reliable sensor device.

  In the sensor device according to the third aspect of the present invention, in particular, since the wiring substrate is formed so that the active layer is patterned to include the second high concentration diffusion region and the sealing semiconductor layer, the sealing semiconductor The layer and the second high concentration diffusion region can be easily formed.

  In the sensor device according to the fourth aspect of the present invention, in particular, a through hole is formed in the substrate layer and the oxide layer of the wiring board so that the second high concentration diffusion region is exposed, and the inner peripheral surface of the through hole. Since the thin film conductive film is formed on the external electrode and the external electrode and the second high concentration diffusion region are electrically connected by the thin film conductive film, the external substrate and the second high concentration diffusion region can be easily electrically connected. Can be formed.

  In the sensor device according to the fifth aspect of the present invention, in particular, since an insulating film is formed between the first high-concentration diffusion region and the sealing joint portion on the one surface of the sensor substrate, Leakage can be prevented and the reliability of the sensor device can be improved.

The acceleration sensor apparatus of Embodiment 1 is shown, (a) is a schematic sectional drawing of A-A 'of FIG. 2, (b) is the principal part enlarged view of (a). It is a schematic plan view of an acceleration sensor apparatus same as the above. The sensor board | substrate in the same is shown, (a) is a schematic plan view, (b) is B-A 'schematic sectional drawing of (a). It is a sensor board | substrate in the same as the above, and is A-A 'schematic sectional drawing of Fig.3 (a). It is a schematic bottom view which shows the sensor board | substrate in the same as the above. It is a circuit diagram of the sensor board | substrate in the same as the above. The wiring board in the above is shown, (a) is a schematic plan view, (b) is a schematic cross-sectional view of A-A 'of (a). The wiring board in the same as above is shown, and is a main part enlarged view of FIG. It is a bottom view of the wiring board in the same as the above. The cover board | substrate in the same as the above is shown, (a) is a schematic plan view, (b) is A-A 'schematic sectional drawing of (a). It is explanatory drawing of the sensor apparatus of a prior art example.

  The sensor device of the present embodiment is an acceleration sensor device, which is formed using a sensor substrate 1 formed using a first semiconductor substrate and a second semiconductor substrate as shown in FIGS. 1 and 2, The other surface side of the sensor substrate 1 (FIG. 1A) formed using the wiring substrate 2 sealed on one surface side of the sensor substrate 1 (the upper surface side of FIG. 1A) and the third semiconductor substrate. And a cover substrate 3 sealed on the lower surface side). Here, the outer peripheral shapes of the sensor substrate 1, the wiring substrate 2, and the cover substrate 3 are rectangular, and the wiring substrate 2 and the cover substrate 3 are formed to have the same outer dimensions as the sensor substrate 1. 1A is a schematic cross-sectional view taken along the line A-A ′ of FIG. 2, and FIG. 1B is an enlarged view of a main part of FIG.

  The sensor substrate 1 described above processes a first SOI wafer having a p-type silicon layer 10c on an insulating oxide layer (buried oxide film) 10b made of a silicon oxide film on a support substrate layer 10a made of a silicon substrate. It is formed by. The wiring substrate 2 is formed by processing a second SOI wafer, and this SOI wafer is provided with an insulating oxide layer (buried oxide film) 20b made of a silicon oxide film on a support substrate layer 20a made of a silicon substrate. Further, a low-resistance silicon active layer 20c is formed on the insulating oxide layer by doping a p-type silicon layer with an n-type impurity having an appropriate concentration. The cover substrate 3 is formed by processing a silicon wafer. That is, in this embodiment, the first SOI wafer constitutes the first semiconductor substrate, the second SOI wafer constitutes the second semiconductor substrate, and the silicon wafer constitutes the third semiconductor substrate. . In the present embodiment, the thickness of the support substrate layer 10a in the first SOI wafer is about 300 μm to 500 μm, the thickness of the insulating oxide layer 10b is about 0.3 μm to 1.5 μm, and the thickness of the silicon layer 10c is 4 μm to 10 μm, the thickness of the support substrate layer 20 a in the second SOI wafer is about 100 μm, the thickness of the insulating oxide layer 20 b is about 0.5 μm, and the thickness of the silicon active layer 20 c is about 5 μm. Moreover, although the thickness of a silicon wafer is about 100-300 micrometers, these numerical values are not specifically limited. The surface of the silicon layer 10c, which is the main surface of the first SOI wafer, is a (100) plane.

  As shown in FIGS. 3 to 5, the sensor substrate 1 includes a frame portion 11 having a frame shape (in this embodiment, a rectangular frame shape), and a weight portion 12 arranged inside the frame portion 11 is on one surface side. In FIG. 1 (a) and FIG. 3 (b), the frame portion 11 is swingably supported via four flexible strip-like bent portions 13 having flexibility. In other words, the sensor substrate 1 is swingably supported by the frame portion 11 via the four flexure portions 13 in which the weight portion 12 disposed inside the frame-shaped frame portion 11 extends from the weight portion 12 in four directions. Has been. Here, the frame portion 11 is formed by using the support substrate layer 10a, the insulating oxide layer 10b, and the silicon layer 10c of the SOI wafer described above. 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 part 12 is continuously integrated with each of the rectangular parallelepiped core part 12a supported by the frame part 11 via the four flexure parts 13 and the four corners of the core part 12a when viewed from the one surface side of the sensor substrate 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 by using the support substrate layer 10a, the insulating oxide layer 10b, and the silicon layer 10c of the first SOI wafer described above, and each accompanying portion 12b supports the first SOI wafer. It is formed using the substrate layer 10a. Thus, the surface of each associated portion 12b on the one surface side of the sensor substrate 1 is from the plane including the surface of the core portion 12a to the other surface side of the sensor substrate 1 (FIGS. 1A and 3B). (Lower surface side). Note that the above-described frame portion 11, weight portion 12, and each bending portion 13 of the sensor substrate 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. 3A and 3B, one direction along one side of the frame portion 11 in the plane parallel to the one surface of the sensor substrate 1 is the positive direction of the x axis. If one direction along the side orthogonal 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. The pair of flexible portions 13 and 13 sandwiching the core portion 12a and the pair of flexible portions 13 and 13 extending in the y-axis direction and sandwiching the core portion 12a are supported by the frame portion 11. 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. 3A) extending 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. 3A) extending 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. Are formed so that the longitudinal direction thereof coincides with the longitudinal direction of the flexure 13 and are connected by wiring (a diffusion layer wiring formed on the sensor substrate 1) so as to constitute the left bridge circuit Bx in FIG. ing. 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. 3A) 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 (lower bending portion 13 in FIG. 3A) extending 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. Are formed so that the longitudinal direction thereof coincides with the longitudinal direction of the bent portion 13 and are connected by wiring (a diffusion layer wiring formed on the sensor substrate 1) so as to constitute the central bridge circuit By in FIG. ing. 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, Rz4 formed in the vicinity of the frame portion 11 are formed for detecting acceleration in the z-axis direction, and constitute the right bridge circuit Bz in FIG. Thus, they are connected by wiring (diffusion layer wiring formed on the sensor substrate 1). 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.

  In FIG. 1 to FIG. 3, illustration of the diffusion layer wiring in the sensor substrate 1 is omitted.

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

  Now, assuming that acceleration is applied to the sensor substrate 1 in the positive x-axis direction while no acceleration is applied to the sensor substrate 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 between the pair of input terminals VDD and GND shown in FIG. 6 from the external power supply, 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. 6 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. 6 changes according to the magnitude of the acceleration in the z-axis direction. Thus, the above-described sensor substrate 1 detects the change in the output voltage of each of the bridge circuits Bx to Bz, so that the acceleration in the x-axis direction, the y-axis direction, and the z-axis direction that acted on the sensor substrate 1 is detected. Can be detected. In this embodiment, the weight part 12 and each bending part 13 comprise a movable part, and each piezoresistor Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4 constitutes a sensing part in the sensor substrate 1. Yes.

By the way, as shown in FIG. 6, the sensor substrate 1 includes two input terminals VDD and GND common to the three bridge circuits Bx, By, and Bz, two output terminals X1 and X2 of the bridge circuit Bx, Two output terminals Y1, Y2 of the bridge circuit By and two output terminals Z1, Z2 of the bridge circuit Bz are provided. These input terminals VDD, GND and output terminals X1, X2, Y1, Y2 , Z1 and Z2 are provided as the first high-concentration diffusion region 19 on the one surface side (that is, the wiring substrate 2 side), and are electrically connected to the second high-concentration diffusion region 29 formed in the wiring substrate 2. It is connected. That is, eight first high concentration diffusion regions 19 are formed on the sensor substrate 1, and eight second high concentration diffusion regions 29 are formed on the wiring substrate 2. Note that the eight first high-concentration diffusion regions 19 are spaced apart in the circumferential direction of the frame portion 11 (two are disposed on each of the four sides of the rectangular frame-shaped frame portion 11).
Each of the piezoresistors Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4, each of the diffusion layer wirings, and the first high concentration diffusion region 19 has an n-type impurity having an appropriate concentration at each formation site in the silicon layer 10c. The piezoresistors Rx1 to Rx4, Ry1 to Ry4, Rz1 to Rz4 and the first high-concentration diffusion region 19 are electrically connected to each other through a diffusion layer wiring.

Here, 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 silicon layer 10c on the one surface side. It is arranged inside the concentration diffusion region 19. Therefore, the insulating film 16 has a structure that is not disposed on the first high-concentration diffusion region 19 and the sealing bonding portion. However, between the first high concentration diffusion region 19 and the sealing bonding portion, the insulating film 16 has a frame shape over the entire circumference, and the width dimension thereof is the first high concentration diffusion region 19 and the sealing bonding region. The insulating film 16 prevents electrical leakage.
As shown in FIGS. 7 to 9, the wiring board 2 has a plurality (eight in this embodiment) of second high-concentration diffusions from the main surface on the sensor board 1 side (the lower surface side in FIG. 7B). The region 29 is formed so as to protrude, and the sealing semiconductor layer 28 is located outside the second high concentration diffusion region 29 over the entire circumference of the peripheral portion of the main surface of the wiring board 2 on the sensor substrate 1 side. The second high concentration diffusion region 29 is formed at substantially the same height. Here, the wiring substrate 2 is formed by processing the second SOI wafer. As described above, the second SOI wafer is an insulating oxide layer made of a silicon oxide film on the support substrate layer 20a made of a silicon substrate. A (buried oxide film) 20b is provided, and a low-resistance silicon active layer 20c is provided on the insulating oxide layer.
The sealing semiconductor layer 28 and the second high-concentration diffusion region 29 are formed using the low-resistance silicon active layer 20c of the second SOI wafer. That is, the sealing semiconductor layer 28 and the second high-concentration diffusion region 29 are formed by dry-etching the low-resistance silicon active layer 20c using the insulating oxide layer 20b of the second SOI wafer as an etching stopper.
Next, through holes are formed in the support substrate layer 20a and the insulating oxide layer 20b from the support substrate layer 20a side of the second SOI wafer so that the second high concentration diffusion region 29 is exposed. The through hole of the support substrate layer 20a is formed by anisotropic etching using the insulating oxide layer 20b as an etching stopper, and the through hole of the insulating oxide layer 20b is formed by etching using dilute hydrofluoric acid.
A thermal insulating film (silicon oxide film) is formed on the inner surface of the through hole and the one surface of the wiring board 2 (upper surface side of FIG. 1A) formed so as to expose the second high concentration diffusion region 29 in this way. An insulating film 23 is formed. Further, a thin film conductive film 24 is formed across the second high-concentration diffusion region 29 exposed on the inner surface of the insulating film 23 and the bottom surface of the through-hole, and this thin film conductive film 24 is formed on the support substrate layer 20a side of the second SOI wafer. The provided external electrode 25 and the second high concentration diffusion region 29 are electrically connected. Here, the external electrode 25 is composed of, for example, a laminated film of a Cu film, a Ni film, and an Au film, and can be used as, for example, a reflow pad. The outer peripheral shape of each external electrode 25 is rectangular.
Note that a displacement space forming recess 21 is formed in the wiring board 2 due to the thickness of the second high-concentration diffusion region 29 and the sealing semiconductor layer 28, and the displacement space forming recess 21 forms the sensor substrate 1. The displacement space of the movable part comprised by the weight part 12 and the bending part 13 is ensured.
As shown in FIG. 10, the cover substrate 3 is formed with 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 substrate 1. 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 cover substrate 3 that faces the sensor substrate 1, but the core portion 12a and each associated portion 12b of the weight portion 12 are formed. The thickness of the portion formed using the support substrate layer 10a is compared with the thickness of the portion formed using the support substrate layer 10a in the frame portion 11 in the thickness direction of the sensor substrate 1. If the weight portion 12 is made thinner by the allowable displacement amount, the sensor substrate 1 may be formed on the other surface side of the sensor substrate 1 in a direction intersecting the other surface without forming the recess 31 in the cover substrate 3. A gap that allows displacement of the weight portion 12 is formed between the weight portion 12 and the cover substrate 3.
By the way, the sensor substrate 1 and the wiring substrate 2 in the acceleration sensor device described above are bonded to the sealing bonding portion 18 and the sealing semiconductor layer 28, and to the first high concentration diffusion region 19 and the second high concentration. The diffusion region 29 is joined, and the sensor substrate 1 and the cover substrate 3 are joined at the peripheral portions of the opposing surfaces. In addition, the acceleration sensor device of this embodiment includes a first SOI wafer on which a large number of sensor substrates 1 are formed, a second SOI wafer on which a large number of wiring substrates 2 are formed, and a silicon wafer on which a large number of cover substrates 3 are formed. After the bonding, the substrate is cut into an acceleration sensor device having a desired chip size by a dicing process. Therefore, the wiring substrate 2 and the cover substrate 3 have the same outer size as the sensor substrate 1, and a small chip size package can be realized and manufacture is facilitated.
Here, as a method for bonding the sensor substrate 1 to the wiring substrate 2 and the cover substrate 3, it is desirable to employ a bonding method that enables bonding at a lower temperature in order to reduce the residual stress of the sensor substrate 1, In the form, room temperature activated bonding is adopted. In normal temperature activated bonding, each bonding surface is irradiated with argon plasma or ion beam or atomic beam in vacuum before bonding to clean and activate each bonding surface, and then the bonding surfaces are brought into contact with each other. Bond at room temperature. In the present embodiment, the first high-concentration diffusion is performed at the same time when the sealing bonding region 18 and the sealing semiconductor layer 28 are bonded by applying an appropriate load at normal temperature by the above-described normal temperature activation bonding. The region 19 and the second high-concentration diffusion region 29 are joined, and the frame portion 11 of the sensor substrate 1 and the peripheral portion of the cover substrate 3 are joined at room temperature by the above-described room temperature activation joining. . Therefore, in the acceleration sensor device of the present embodiment, the bonding between the sensor substrate 1 and the wiring substrate 2 is a Si—Si bonding, and the bonding between the sensor substrate 1 and the cover substrate 3 is also a Si—Si bonding. Compared with the case where the sensor substrate 1, the wiring substrate 2 and the cover substrate 3 are joined by a method requiring heating such as solder reflow or anodic bonding, the piezo resistors Rx1 to Rx4 and Ry1 to Ry4 constituting the sensing unit. There is an advantage that Rz1 to Rz4 are not easily affected by thermal stress. In the present embodiment, since the sensor substrate 1, the wiring substrate 2, and the cover substrate 3 are formed of Si, which is the same semiconductor material, the linear expansion coefficient difference between the sensor substrate 1, the wiring substrate 2, and the cover substrate 3. As compared with the case where the wiring substrate 2 and the cover substrate 3 are formed of a material different from that of the sensor substrate 1, the influence of the stress caused by the residual stress (residual stress in the sensor substrate 1) on the output signal of the bridge circuit can be reduced. Variations in sensor characteristics can be reduced. The sensor substrate 1 is formed by processing the first SOI wafer. However, the sensor substrate 1 is not limited to the SOI wafer, and may be formed by processing a silicon wafer, for example.
In the acceleration sensor device of the present embodiment described above, a part of one surface of the sensor substrate 1 formed using the first semiconductor substrate is made into the first high concentration diffusion region 19 by adding impurities, and the second A part of the surface of the wiring substrate 2 formed using the semiconductor substrate is made into a second high concentration diffusion region 29 by adding impurities, and the first high concentration diffusion region 19 and the second high concentration diffusion region 29 are at room temperature. Since the active bonding is performed, the sensor device can be manufactured through a simple manufacturing process, and the first high-concentration diffusion region 19 and the second high-concentration diffusion region 29 are firmly bonded by room-temperature activation bonding between semiconductors. Therefore, a highly reliable sensor device can be provided.

  In the sensor device of this embodiment, in particular, a part of the surface of the wiring board 2 on the sensor substrate 1 side is formed to protrude as the second high concentration diffusion region 29 and the second high concentration diffusion. Outside the region 29, a sealing semiconductor layer 28 is formed at substantially the same height as the second high-concentration diffusion region 29 over the entire circumference of the peripheral portion on the surface of the wiring substrate 2, and the sensor substrate 1 and the wiring substrate 2 are bonded at the first high-concentration diffusion region 19 and the second high-concentration diffusion region 29 at normal temperature, and at the same time for sealing over the entire circumference of the peripheral portion on the surface of the sensor substrate 1. Since the portion 18 and the sealing semiconductor layer 28 are sealed by normal temperature activation bonding, the first high-concentration diffusion region 19 and the sealing bonding portion 18 in the sensor substrate 1 are formed with a smooth surface. What is necessary is a simple manufacturing process and sensor board 1 Can be formed, the sensor substrate 1 and the wiring board 2, to be firmly sealed by the room temperature activation bonding of semiconductor together, it is possible to provide a highly reliable sensor device.

  In the sensor device of this embodiment, in particular, the low-resistance silicon active layer 20c of the second SOI wafer is patterned so that the second high-concentration diffusion region 29 and the sealing semiconductor layer 28 are provided. Since the substrate 2 is formed, the sealing semiconductor layer 28 and the second high-concentration diffusion region 29 can be easily formed.

  In the sensor device of the present embodiment, in particular, through holes are formed in the support substrate layer 20a and the insulating oxide layer 20b of the wiring board 2 so that the second high concentration diffusion region 29 is exposed. Since the thin film conductive film 24 is formed on the peripheral surface and the external electrode 25 and the second high concentration diffusion region 29 are electrically connected by the thin film conductive film 24, the external electrode 25 and the second high concentration diffusion region 29 can be easily connected. Can be formed.

  In the sensor device of the present embodiment, the insulating film 16 is formed between the first high-concentration diffusion region 19 and the sealing bonding portion 18 on the one surface of the sensor substrate 1 in particular. Leakage can be prevented and the reliability of the sensor device can be improved.

DESCRIPTION OF SYMBOLS 1 Sensor substrate 2 Wiring board 3 Cover substrate 11 Frame part 12 Weight part 13 Flexing part 18 Sealing junction part 19 1st high concentration diffusion area | region 21 Displacement space formation recessed part 25 External electrode 28 Sealing semiconductor layer 29 2nd high Concentration diffusion region

Claims (5)

In a sensor device comprising: a sensor substrate formed using a first semiconductor substrate and provided with a sensing unit; and a wiring substrate formed using a second semiconductor substrate and sealed to one surface of the sensor substrate.
A part of the one surface of the sensor substrate is doped to form a first high concentration diffusion region, and the first high concentration diffusion region is electrically connected to the sensing unit,
A part of the surface of the wiring board on the sensor substrate side is doped to form a second high concentration diffusion region, and the second high concentration diffusion region is electrically connected to an external electrode provided outside,
A sensor device, wherein the sensor substrate and the wiring substrate are sealed by the first high-concentration diffusion region and the second high-concentration diffusion region being joined at normal temperature activation. A part of the surface of the wiring substrate on the sensor substrate side is formed to protrude as the second high concentration diffusion region, and outside the second high concentration diffusion region, a peripheral portion on the surface of the wiring substrate is formed. A sealing semiconductor layer is formed at substantially the same height as the second high-concentration diffusion region over the entire circumference,
The sensor substrate and the wiring substrate have the first high-concentration diffusion region and the second high-concentration diffusion region joined at normal temperature activation bonding, and the sealing joint portion over the entire circumference of the peripheral portion on the surface of the sensor substrate, 2. The sensor device according to claim 1, wherein the sensor device is sealed by being subjected to normal temperature activated bonding with the sealing semiconductor layer.   The second semiconductor substrate on which the wiring substrate is formed is an SOI substrate including a substrate layer, an oxide layer, and an doped active layer, and the active layer is patterned to form a second high concentration diffusion region and a sealing semiconductor. The sensor device according to claim 2, wherein the wiring board is formed so as to include a layer.   A through hole is formed in the substrate layer and the oxide layer of the wiring substrate so that the second high concentration diffusion region is exposed, and a thin film conductive film is formed on the inner peripheral surface of the through hole. 4. The sensor device according to claim 3, wherein the high concentration diffusion region is electrically connected.   5. The sensor device according to claim 2, wherein an insulating film is formed between the first high-concentration diffusion region and the sealing joint portion on the one surface of the sensor substrate. .

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