JP2014112038A - Physical quantity sensor and physical quantity sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a physical quantity sensor and a physical quantity sensor device which have excellent detection accuracy and are excellent in thermal stress resistance and miniaturization.SOLUTION: A physical quantity sensor device 10 comprises: a sensor substrate 2; a wiring substrate 3; a junction 4 bonding the sensor substrate 2 and the wiring substrate 3; and a coating part 6 covering the sensor substrate 2. The sensor substrate 2 is arranged above the wiring substrate 3 and includes an upper surface and a side surface. The junction 4 has a smaller width dimension than those of the sensor substrate 2 and the wiring substrate 3 in a cross-sectional view. In the cross-sectional view, the sensor substrate 2 is provided with a bevelled part 2o that has an outline 2t inwardly from a virtual outline 2s formed of an extended line 2q of the upper surface and an extended line 2r of the side surface. The coating part 6 has elastic modulus smaller than that of the sensor substrate 2.

Description

  The present invention relates to a physical quantity sensor including a sensor base material that detects a physical quantity, and a physical quantity sensor device in which the physical quantity sensor is covered with a covering portion.

  In the physical quantity sensor and the physical quantity sensor device, the height and size are being reduced. Therefore, the thickness dimension and the planar dimension of the physical quantity sensor and the physical quantity sensor device are decreasing year by year.

  FIG. 10 is a schematic cross-sectional view of the physical quantity sensor disclosed in Patent Document 1. As shown in FIG. 10, the physical quantity sensor 101 disclosed in Patent Document 1 includes a sensitive base material (SOI layer) 102b that detects a physical quantity, and a support base material 102a that supports the sensitive base material 102b. Yes.

  The support base material 102a and the sensitive base material 102b are joined via the oxide insulating layers 102c and 102d. The sensor base material 102 is composed of the support base material 102a, the oxide insulating layers 102c and 102d, and the sensitive base material 102b. The sensor base material 102 is formed by finely processing an SOI (Silicon on Insulator) substrate. The sensitive substrate 102b includes a fixed electrode 102e, a movable electrode 102f, a frame body layer 102h, and the like.

  A wiring substrate (wiring substrate) 103 is provided facing the sensor substrate 102. The wiring base material 103 includes an insulating layer, a second sealing metal layer 103j, and the like on the upper surface of the silicon substrate 103a.

  The sensor base material 102 and the wiring base material 103 are joined by a joint portion 104. The joint 104 is formed as follows. First, the sensitive base material 102b is cut into a square frame shape to form the frame body layer 102h. Next, the first sealing metal layer 102j formed on the lower surface of the frame body layer 102h and the second sealing metal layer 103j formed on the upper surface of the silicon substrate 103a are pressurized while being heated to form eutectic bonding. Alternatively, diffusion bonding is performed. The layer subjected to eutectic bonding or diffusion bonding is the bonding layer 104a.

  In this manner, the bonding portion 104 is integrally formed by bonding the first sealing metal layer 102j and the second sealing metal layer 103j via the bonding layer 104a. And the junction part 104 is connected with the frame body layer 102h and the oxide insulating layer 102c on the upper surface side. Therefore, the joining portion 104 is connected to the frame body layer 102h and the oxide insulating layer 102c and stacked in the vertical direction, and this portion forms a structure having a long axis in the vertical direction.

  FIG. 11 is a schematic cross-sectional view of the physical quantity sensor device disclosed in Patent Document 1. In the physical quantity sensor device 110, as shown in FIG. 11, the physical quantity sensor 101 is housed in a package 107 made of resin or the like. The physical quantity sensor device 110 is configured such that the surface of the physical quantity sensor 101 is covered with a covering portion 106 made of resin or the like in order to protect the physical quantity sensor 101 from mechanical damage, moisture, contaminants, and the like.

WO2010 / 032821

  When the physical quantity sensor device 110 is used, it will be described with reference to FIGS. 10 and 11. However, the temperature of the physical quantity sensor device 110 may fluctuate due to the ambient temperature, the heat generated by the physical quantity sensor 101, or the like. Therefore, the thermal stress generated by the difference in thermal expansion coefficient between the covering portion 106 and the physical quantity sensor 101 may be applied to the physical quantity sensor 101.

  When the sensitive base material 102b is deformed by this thermal stress, the output of the physical quantity detected by the sensitive base material 102b may fluctuate. Therefore, a material having a low elastic modulus is used for the covering portion 106 so as to relieve the thermal stress. That is, since the covering portion 106 has a low elastic modulus, the covering portion 106 is elastically deformed by the thermal stress and relaxes the thermal stress.

  However, since the joining portion 104, the frame body layer 102h, and the oxide insulating layer 102c are stacked and connected to form a long-axis structure, thermal stress is easily concentrated. Therefore, the joint portion 104 is easily deformed, and problems such as peeling and cracking are likely to occur. In addition, the thickness of the sensitive base material 102b is reduced by reducing the height of the physical quantity sensor 101, and the sensitive base material 102b is easily deformed. Therefore, when the joint 104 is deformed, the sensitive base material 102b may be deformed via the frame body layer 102h connected to the joint 104, and the output of the physical quantity may fluctuate.

  If the planar dimension of the joint 104 is reduced in order to reduce the size of the physical quantity sensor 101, the joint 104 becomes weak in strength. For this reason, the joint portion 104 in which thermal stress is easily applied in a concentrated manner is further easily deformed, and problems such as peeling and cracking are likely to occur. As a result, the sensitive base material 102b is easily deformed, and the output of the physical quantity further varies.

  As described above, in the physical quantity sensor 101 and the physical quantity sensor device 110 disclosed in Patent Document 1, the thermal stress cannot be sufficiently relaxed only by using a low elastic modulus resin for the covering portion 106. Therefore, thermal stress is intensively applied to the joint 104, and the joint 104 is deformed. In some cases, defects such as peeling and cracking may occur. In addition, the sensitive base material 102b may be deformed according to the thermal stress, and the output of the sensitive base material 102b may fluctuate. Further, it is difficult to reduce the size of the physical quantity sensor 101 and the physical quantity sensor device 110.

  An object of the present invention is to provide a physical quantity sensor and a physical quantity sensor device that have a good detection accuracy and are excellent in thermal stress resistance and miniaturization.

  The physical quantity sensor of the present invention includes a sensor base material that detects a physical quantity, a wiring base material that is joined to the sensor base material, and a joint portion that joins the sensor base material and the wiring base material. A physical quantity sensor having a base material disposed on an upper side of the wiring base material, having an upper surface and a side surface, and the joint portion having a width dimension smaller than the sensor base material and the wiring base material in a cross-sectional view, The sensor base material has a chamfered portion having a contour line inside a virtual contour line formed from an extension line of the upper surface and an extension line of the side surface in a sectional view.

  Since the physical quantity sensor of the present invention is protected from mechanical damage, moisture, contaminants, etc., the surface thereof is used by covering the surface with a coating portion made of resin or the like. Therefore, when the physical quantity sensor is used, the temperature of the physical quantity sensor and the covering portion may fluctuate due to the ambient temperature, the heat generated by the sensor base material, or the like. For this reason, thermal stress generated by a difference in thermal expansion coefficient between the covering portion and the sensor base material may be applied to the sensor base material.

  In order to solve the problems as described above, in the present invention, in the sensor base material, in a cross-sectional view, inside the virtual contour line formed from the extension line of the sensor base material upper surface and the sensor base material side surface extension A chamfered portion having a contour line is formed.

  By setting it as such a structure, the concentrated load of the thermal stress with respect to a junction part is suppressed. As a result, it is possible to prevent the joint from being deformed, and peeling or cracking from occurring in the joint. As a result, deformation of the sensor base material is also suppressed.

  Therefore, according to the present invention, it is possible to provide a physical quantity sensor that has good detection accuracy and is excellent in thermal stress resistance and miniaturization.

  The physical quantity sensor device of the present invention includes a sensor base material that detects a physical quantity, a wiring base material that is joined to the sensor base material, a joining portion that joins the sensor base material and the wiring base material, and the sensor base material. And the sensor base material is disposed on the upper side of the wiring base material, and has an upper surface and a side surface, and the joint portion has the sensor base material and the wiring base in a cross-sectional view. A physical quantity sensor device having a width dimension smaller than that of a material, wherein the sensor base material has a chamfer having a contour line inside a virtual contour line formed from an extension line of the upper surface and an extension line of the side surface in a cross-sectional view. And an elastic modulus of the covering portion is smaller than an elastic modulus of the sensor base material.

  In the physical quantity sensor device of the present invention, in order to protect the physical quantity sensor from mechanical damage, moisture, contaminants, etc., the surface of the physical quantity sensor is covered with a covering portion made of resin or the like. For this reason, when the physical quantity sensor device is used, the temperature of the physical quantity sensor device may fluctuate due to the ambient temperature or the heat generated by the physical quantity sensor. May be weighted to the material.

  Therefore, in the present invention, a chamfered portion having a contour line on the inner side of the virtual contour line formed from the extension line of the sensor base material upper surface and the sensor base material side surface is formed in the sensor base material in a cross-sectional view. ing.

  By setting it as such a structure, the concentrated load of the thermal stress with respect to a junction part is suppressed. As a result, it is possible to prevent the joint from being deformed, and peeling or cracking from occurring in the joint. As a result, deformation of the sensor base material is also suppressed.

  Therefore, according to the present invention, it is possible to provide a physical quantity sensor device that has good detection accuracy and is excellent in thermal stress resistance and miniaturization.

  It is preferable that the chamfered portion is an inclined surface that is inclined from the upper surface to the side surface. If it is such an aspect, the chamfering part which has a contour line inside a virtual contour line formed from the extension line of a sensor base material upper surface and the extension line of a sensor base material side surface can be formed in cross-sectional view.

  It is preferable that the angle of the inclined surface inclined from the extended line of the side surface is 35 ° to 55 °. In such an embodiment, the supporting base material suppresses deformation of the sensitive base material due to external force such as thermal stress, and thus it is possible to detect the physical quantity with high accuracy.

  It is preferable that the inclined surface includes a plurality of surfaces having different inclination angles. If it is such an aspect, the chamfering part which has a contour line inside a virtual contour line formed from the extension line of a sensor base material upper surface and the extension line of a sensor base material side surface can be formed in cross-sectional view.

  It is preferable that the outline of the chamfered portion includes at least one line segment parallel to the extension line of the upper surface and at least one line segment parallel to the extension line of the side surface in a cross-sectional view. If it is such an aspect, the chamfering part which has a contour line inside a virtual contour line formed from the extension line of a sensor base material upper surface and the extension line of a sensor base material side surface can be formed in cross-sectional view.

  It is preferable that the chamfered portion is a curved surface. If it is such an aspect, the chamfering part which has a contour line inside a virtual contour line formed from the extension line of a sensor base material upper surface and the extension line of a sensor base material side surface can be formed in cross-sectional view.

  It is preferable that the side surface includes the chamfered portion and a vertical surface continuously provided below the chamfered portion. With such an aspect, when cutting the base material on which the sensor base material is formed to cut out the sensor base material, the dimensional accuracy in the rotating shaft direction of the dicing blade can be improved. It is possible to cut out the substrate.

  It is preferable that the chamfered portion overlaps the joint portion in plan view. If it is such an aspect, it is possible to suppress effectively the thermal stress weighted to a junction part.

  The sensor base material is composed of a sensitive base material that detects a physical quantity and a support base material that supports the sensitive base material, and the vertical dimension of the support base material is larger than the vertical dimension of the sensitive base material. Is preferred. With such an aspect, the supporting base material suppresses deformation of the sensitive base material due to external force such as thermal stress, and therefore it is possible to detect the physical quantity with high accuracy.

  The covering portion is preferably made of a silicone resin or a fluorine resin. According to such an aspect, the elastic modulus of the covering portion can be made smaller than the elastic modulus of the sensor base material.

  Therefore, according to the present invention, it is possible to provide a physical quantity sensor and a physical quantity sensor device that have good detection accuracy and are excellent in thermal stress resistance and miniaturization.

1 is a schematic plan view of a physical quantity sensor showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line AA shown in FIG. It is a section schematic diagram of a physical quantity sensor device showing an embodiment of the present invention. It is explanatory drawing of a chamfering part. It is explanatory drawing of the moment of the force which acts on the inner side lower end part of a coupling body. It is explanatory drawing of the force which acts on the inner side lower end part of a coupling body intensively. It is a section schematic diagram of the physical quantity sensor device which is the 1st modification. It is a section schematic diagram of the physical quantity sensor device which is the 2nd modification. It is a section schematic diagram of the physical quantity sensor device which is the 3rd modification. 2 is a schematic cross-sectional view of a physical quantity sensor disclosed in Patent Document 1. 1 is a schematic cross-sectional view of a physical quantity sensor device disclosed in Patent Document 1.

  Hereinafter, a physical quantity sensor and a physical quantity sensor device according to embodiments of the present invention will be described in detail with reference to the drawings. In addition, the dimension of each drawing is changed and shown suitably.

  FIG. 1 is a schematic plan view of a physical quantity sensor showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line AA shown in FIG. FIG. 3 is a schematic cross-sectional view of a physical quantity sensor device showing an embodiment of the present invention. FIG. 4 is an explanatory diagram of the chamfered portion.

  As shown in FIG. 2, the sensor base material 2 includes a support base material 2a, a sensitive base material 2b, and oxide insulating layers 2c and 2d. In this embodiment, an SOI substrate is used as a semiconductor process. These are formed using the microfabrication technology. The sensitive substrate 2b is formed by finely processing an SOI layer, and a fixed electrode 2e, a movable electrode 2f, a conductive layer 2g, and a frame layer 2h are separately formed on the sensitive substrate 2b. Further, part of the oxide insulating layer is removed and separated from each other to form oxide insulating layers 2c and 2d.

  As shown in FIG. 4, a chamfered portion 2 o is formed on the support base 2 a included in the sensor base 2. The chamfered portion 2o has a contour line 2t inside a virtual contour line 2s formed from an extension line 2q of the upper surface 2n of the support base material 2a and an extension line 2r of the side surface 2p of the support base material 2a in a sectional view. Yes.

  In the present embodiment, the chamfered portion 2o is an inclined surface 2o that is inclined from the upper surface 2n to the side surface 2p of the support substrate 2a included in the sensor substrate 2. And the inclined surface 2o is formed in frame shape in the outer periphery of the support base material 2a, as shown in FIG.

  As shown in FIG. 2, the wiring base material 3 includes a silicon substrate 3a, an insulating layer 3c, a wiring layer 3k, and a pad electrode 3m. The insulating layer 3c is an inorganic insulating layer such as silicon oxide, silicon nitride, or aluminum oxide, and is formed on the surface of the silicon substrate 3a by sputtering, chemical vapor deposition, or the like. A wiring layer 3k is embedded in the insulating layer 3c, and an end of the wiring layer 3k is connected to a pad electrode 3m for outputting a detection signal to the outside. The wiring layer 3k and the pad electrode 3m are formed of aluminum, an aluminum alloy, gold, or the like.

  The sensor base material 2 and the wiring base material 3 are provided to face each other, and the first connection metal layer 2i and the second connection metal layer are provided on the sensor base material 2 and the wiring base material 3 so as to face each other. 3i, and a first sealing metal layer 2j and a second sealing metal layer 3j are formed. Then, the first connecting metal layer 2i and the second connecting metal layer 3i, and the first sealing metal layer 2j and the second sealing metal layer 3j face each other, and the sensor base member 2 and the wiring are heated while heating. The substrate 3 is pressurized, and the first connection metal layer 2i and the second connection metal layer 3i, and the first sealing metal layer 2j and the second sealing metal layer 3j are eutectic bonded or diffusion bonded. The first sealing metal layer 2j and the second sealing metal layer 3j, and the eutectic bonding or diffusion bonding layer between the first connection metal layer 2i and the second connection metal layer 3i are bonded to each other. It is the layer 4a or the bonding layer 4b.

  In the present embodiment, the second connection metal layer 3i and the second sealing metal layer 3j are made of aluminum or an aluminum alloy. The first connection metal layer 2i and the first sealing metal layer 2j are formed of germanium that can be eutectic bonded or diffusion bonded to aluminum or an aluminum alloy.

  As shown in FIGS. 1 and 2, the frame layer 2h is formed in a frame shape on the outer periphery of the sensitive base material 2b by cutting the sensitive base material 2b into a square frame shape. An oxide insulating layer 2c is left between the frame body layer 2h and the support base 2a, and a first sealing metal layer 2j is formed on the lower surface of the frame body layer 2h. The wiring substrate 3 is provided with a second sealing metal layer 3j that is bonded to the first sealing metal layer 2j via the insulating layer 3c.

  Therefore, the square frame-shaped oxide insulating layer 2c is bonded to the upper surface of the square frame-shaped frame body layer 2h, and the rectangular frame-shaped first sealing metal is bonded to the lower surface of the square frame-shaped frame body layer 2h. A square frame-shaped second sealing metal layer 3j is bonded via the layer 2j and subsequently the bonding layer 4a.

  In the present embodiment, the first sealing metal layer 2j and the second sealing metal layer 3j are integrally formed in a square frame shape via the bonding layer 4a to form the bonding portion 4. . And the junction part 4 is connected with the frame body layer 2h and the oxide insulating layer 2c on the upper surface side. Therefore, the joint portion 4 is connected to the frame body layer 2h and the oxide insulating layer 2c and stacked in the vertical direction, and this portion forms a structure having a long axis in the vertical direction.

  The sensor base 2 and the wiring base 3 are joined by the joint 4, and the support base 2 a and the wiring base 3 are surrounded by the oxide insulating layer 2 c, the frame body layer 2 h, and the joint 4. A hollow gap 5 hermetically sealed is formed.

  In the gap 5, the movable electrode 2f and the fixed electrode 2e are arranged in parallel with a space therebetween. When acceleration is applied to the physical quantity sensor 1, the distance between the movable electrode 2f and the fixed electrode 2e changes, and the capacitance between the movable electrode 2f and the fixed electrode 2e varies. Therefore, the physical quantity sensor 1 of the present embodiment is a capacitive acceleration sensor that detects acceleration based on a change in capacitance. Thus, the sensitive substrate 2b having the movable electrode 2f and the fixed electrode 2e detects acceleration (physical quantity).

  The thickness (vertical direction) dimension of the physical quantity sensor 1 of the present embodiment will be described with reference to FIG. The support substrate 2a has a thickness of about 0.2 to 0.7 mm, the sensitive substrate 2b has a thickness of about 10 to 20 μm, and the oxide insulating layers 2c and 2d have a thickness of about 1 to 3 μm.

  The planar dimensions of the physical quantity sensor 1 of the present embodiment will be described with reference to FIG. The planar dimensions of the support base 2a and the sensitive base 2b are about 0.5 to 1.5 mm × 0.7 to 2.0 mm, and the planar dimension of the silicon substrate 3a is 0.7 to 2.0 mm × 0.7. About 2.0 mm. The plane dimension in the direction in which the width of the joint 4 is narrow is about 20 to 60 μm.

  In the present embodiment, the physical quantity sensor 1 is a capacitive acceleration sensor, but is not limited thereto. The physical quantity sensor 1 can be configured as a pressure sensor, a vibration gyro, or the like.

  In the present embodiment, the joint 4 is connected to the frame body layer 2h and the oxide insulating layer 2c to form a long-axis structure in the vertical direction, but is not limited thereto. It is also possible to form a structure having a long axis in the vertical direction by being connected to other layers.

  Hereinafter, the physical quantity sensor device 10 of this embodiment will be described with reference to FIGS. 1, 2, and 3. The physical quantity sensor device 10 is configured by housing the physical quantity sensor 1 in a package 7 made of resin or the like. Although not shown, the back surface 1a of the physical quantity sensor 1 is fixed to the bottom surface 7a of the package 7 using a die bond material or the like.

  The physical quantity sensor 1 is covered with a covering portion 6 made of resin or the like in order to be protected from mechanical damage, moisture, contaminants, and the like. Although not shown in FIG. 3, the package 7 may contain an IC (Integrated Circuit) that controls the physical quantity sensor 1 together with the physical quantity sensor 1.

  When acceleration is applied to the physical quantity sensor 1, the sensitive substrate 2b operates. A force acts between the physical quantity sensor 1 and the covering portion 6 by this operation or the operation of the support base 2a in conjunction with this operation. In the present embodiment, a material having a smaller elastic modulus than that of the sensor base 2 is used for the covering portion 6. Therefore, the force generated between the physical quantity sensor 1 and the covering portion 6 is alleviated by the elastic deformation of the covering portion 6. Therefore, the operation of the sensitive substrate 2b is suppressed from being restricted by the covering portion 6, and the physical quantity sensor 1 can detect acceleration with high accuracy.

In the present embodiment, a silicone resin, a fluorine resin, or the like is used as a low elastic modulus material. The Young's modulus (Mpa) and the thermal expansion coefficient (/ ° C.) of the silicone resin used in the present embodiment are about 0.5 to 200, and about 15 × 10 ⁻⁵ to 40 × 10 ⁻⁵ . Moreover, the Young's modulus (Mpa) and the thermal expansion coefficient (/ ° C.) of the fluorine-based resin used in this embodiment are about 1 to 200, and are about 15 × 10 ⁻⁵ to 40 × 10 ^−5. .

  When the physical quantity sensor device 10 is used, the ambient temperature may fluctuate due to room temperature, heat generation from surrounding equipment, or the like. Also, due to the heat generation of the sensor base 2 caused by the movement of the movable electrode 2f, the heat generation due to the Joule heat of the wiring layer 3k and the bonding layer 4a, etc., and when the IC is housed in the package 7, In addition, the temperature of the physical quantity sensor 1 varies.

  Due to a change in ambient temperature or a temperature change in the physical quantity sensor 1, a thermal stress is generated due to a difference in thermal expansion coefficient between the physical quantity sensor 1 and the covering portion 6, and this thermal stress is applied to the physical quantity sensor 1. When this thermal stress is applied to the sensitive substrate 2b via the support substrate 2a or directly, the sensitive substrate 2b is deformed. Therefore, the output may fluctuate due to a change in the interval between the movable electrode 2f and the fixed electrode 2e due to the thermal stress.

  In the present embodiment, a material having a smaller elastic modulus than that of the sensor base 2 is used for the covering portion 6. Therefore, when a thermal stress is generated between the physical quantity sensor 1 and the covering portion 6, the covering portion 6 is elastically deformed, so that deformation of the sensitive base material 2 b is suppressed. That is, by using a material having a low elastic modulus for the covering portion 6, thermal stress is relaxed and fluctuations in output are suppressed.

  However, as shown in FIGS. 2 and 3, the physical quantity sensor 1 having a structure in which the sensor base 2 and the wiring base 3 are joined by the joint 4 having a small width dimension, or the physical quantity sensor device 10 including the physical quantity sensor 1. In, the use of a material having a low elastic modulus for the covering portion 6 does not sufficiently mitigate thermal stress. Further, the physical quantity sensor 1 is being reduced in height, and the physical quantity sensor 1 has a small size in the height direction. Therefore, the thickness (the dimension in the height direction) of the sensitive base material 2b is thin, and the deformation of the sensitive base material 2b cannot be sufficiently suppressed only by using a low elastic modulus material for the covering portion 6. .

  Therefore, in this embodiment, as shown in FIGS. 1 to 4, as the chamfered portion 2 o, the support base material 2 a is provided with an inclined surface 2 o that is inclined from the upper surface 2 n to the side surface 2 p. As shown in FIG. 4, the inclined surface 2o is inside the virtual contour 2s formed by the extension line 2q of the upper surface 2n of the support base material 2a and the extension line 2r of the side surface 2p of the support base material 2a in a cross-sectional view. Has an outline 2t.

  Assuming that the thermal stress caused by the temperature rise acts from the periphery of the physical quantity sensor 1 having the configuration shown in FIG. 3, as a result of simulation using the finite element method, the outer upper end 3 u of the oxide insulating layer 2 c connected to the joint 4 It was found that thermal stress was intensively applied to the inner lower end 3w (shown in FIG. 4) of the joint 4 (shown in FIG. 4) and the joint 4. As shown in FIG. 4, the outer upper end 3u and the inner lower end 3w are positioned at both ends of a longitudinally long structure formed by the joint 4 with the frame body layer 2h and the oxide insulating layer 2c.

  FIG. 5 is a calculation result of thermal stress intensively applied to the inner lower end 3w of the joint 4 by simulation. Table 1 shows the physical constants of the constituent members used in the calculation. This simulation assumes that there was no thermal stress before the temperature rose, and that the temperature rose by 75 ° C.

  The thermal stress intensively applied to the inner lower end 3w of the joint 4 will be described with reference to FIG. 4, as shown in FIG. 5, but the extension line 2q dimension of the upper surface 2n and the extension line 2r of the side surface 2p. It can be seen that as the size is increased, that is, as the chamfering amount is increased, the size is suppressed.

  Further, when the extension line 2q dimension of the upper surface 2n and the extension line 2r dimension of the side surface 2p are 0, the inclined surface 2o is not formed. It can be seen that the thermal stress that is intensively applied to the inner lower end 3w of the portion 4 is suppressed.

  The simulation result can also be interpreted as follows. In the present embodiment, as shown in FIG. 4, a portion between the inclined surface 2 o and the virtual contour 2 s is cut in a cross-sectional view to form the inclined surface 2 o. Therefore, according to the present embodiment, instead of the force (referred to as the first force) caused by the thermal stress applied to the extension line 2q and the extension line 2r of the virtual outline 2s, the inclined surface 2o is weighted. A force (second force) resulting from the thermal stress is born.

  The first force and the second force are likely to be concentrated and act on a location where strength is weak or a location where the force tends to concentrate structurally. In the physical quantity sensor 1, the joint portion 4, the frame body layer 2h, and the oxide insulating layer 2c are stacked and connected to form a long-axis structure in the vertical direction. Further, the joint 4 has a portion having a width dimension smaller than that of the sensor base 2 and the wiring base 3 in a cross-sectional view. Therefore, since the frame body layer 2h and the oxide insulation 2c are stacked and connected to the joint portion 4 having a narrow width dimension to form a structure extending in the height direction, the first force and the second force This force tends to act as a moment of force with the joint 4 as a fulcrum. From the simulation results, the fulcrum is the inner lower end 3w shown in FIG.

  The moment of force resulting from the first force is the component of thermal stress perpendicular to the direction from each point of the virtual contour 2s toward the joint 4 at each point of the virtual contour 2s, and each of the virtual contour 2s. The product of the point and the distance between the joints 4 is calculated, and this product is integrated on the virtual contour 2s. The moment of the force resulting from the second force is the component of thermal stress orthogonal to the direction from each point of the inclined surface 2o toward the joint 4 at each point of the inclined surface 2o, and each point of the inclined surface 2o. The product with the distance of the part 4 is calculated, and this product is integrated on the inclined surface 2o. The length of the inclined surface 2o is shorter than the length of the virtual contour 2s, and the distance between the inclined surface 2o and the joint 4 is smaller than the distance between the virtual contour 2s and the joint 4. Therefore, the moment of force caused by the second force is smaller than the moment of force caused by the first force.

  In this embodiment, while using the coating | coated part 6 with a low elasticity modulus, the inclined surface 2o inclined from the upper surface 2n to the side surface 2p is provided in the support base material 2a.

  Therefore, as shown in FIGS. 2 and 3, the physical quantity sensor 1 having a structure in which the sensor base 2 and the wiring base 3 are joined by the joint 4 having a small width dimension, or the physical quantity sensor device 10 including the physical quantity sensor 1. Also, the thermal stress caused by the temperature fluctuation is restrained from being concentrated on the joint 4. As a result, the joining portion 4 is deformed, and the occurrence of peeling or cracking at the joining portion 4 is suppressed. Therefore, the physical quantity sensor 1 and the physical quantity sensor device 10 of this embodiment are excellent in thermal stress resistance.

  As a result, the deformation of the sensitive base material 2b due to the deformation of the joint portion 4 is suppressed. Therefore, the physical quantity sensor 1 is reduced in height, but the thickness of the sensitive base material 2b is thin, but the temperature changes. It is possible to sufficiently suppress deformation of the sensitive substrate 2b against thermal stress. Therefore, according to the physical quantity sensor 1 and the physical quantity sensor device 10 of the present embodiment, good detection accuracy is possible.

  Therefore, according to the present embodiment, it is possible to provide a physical quantity sensor and a physical quantity sensor device that have good detection accuracy and are excellent in thermal stress resistance.

  When peeling or cracking occurs at the joint 4, the hermetic sealing of the hollow gap 5 surrounded by the joint 4 is impaired. As a result, air containing moisture may enter the gap 5, the dielectric constant in the gap 5 changes, and the output may fluctuate. According to the present embodiment, it is possible to suppress the output fluctuation caused by the change in the dielectric constant, thereby enabling good detection accuracy.

  Moreover, the inclined surface 2o has overlapped with the junction part 4 by planar view, as shown in FIG. 2, FIG. Therefore, since the upper surface 2n of the support base 2a that loads the thermal stress caused by the temperature fluctuation from the overhead of the joint portion 4 is cut, the thermal stress applied to the joint portion 4 can be effectively suppressed. Is possible.

  Moreover, the thickness (up-down direction) dimension of the support base material 2a is larger than the thickness dimension of the sensitive base material 2b, as shown in FIGS. Therefore, it is possible to form the sensitive base material 2b that detects acceleration with high sensitivity, and to form the support base material 2a that protects the sensitive base material 2b from external forces such as thermal stress.

  Further, as shown in FIG. 4, the inclined surface 2o is formed such that an angle 2y inclined from the side extension line 2r is 35 ° to 55 °. If the tilt angle 2y is less than 35 °, the dimension of the extension line 2q on the upper surface is relatively smaller than the dimension of the extension line 2r on the side surface, and the thermal stress applied to the joint 4 is concentrated sufficiently. Cannot be suppressed. If the tilt angle 2y is larger than 55 °, the support base material 2a becomes thin, so that it is difficult to suppress the sensitive base material from being deformed by an external force such as thermal stress. Therefore, if the angle 2y is 35 ° to 55 °, the support base material 2a suppresses deformation of the sensitive base material due to an external force such as thermal stress, so that the physical quantity can be detected with high accuracy. .

  Silicone resin and fluorine-based resin are materials having a low elastic modulus, but some have a high coefficient of thermal expansion. For this reason, when a resin having a high coefficient of thermal expansion is used, such a resin is greatly deformed due to temperature fluctuations, and thus there is a feature that the thermal stress cannot be sufficiently relaxed by elastic deformation due to thermal stress.

  Therefore, when such a resin having a large coefficient of thermal expansion is used for the covering portion, defects such as peeling and cracking are likely to occur at the joint portion, the output of the sensitive base material is likely to be offset, The output of the base material may easily fluctuate.

  Therefore, in this embodiment, as shown in FIG. 2 and FIG. 3, the inclined surface 2o is formed on the support base 2a. As a result, since it is possible to suppress the thermal stress caused by temperature fluctuations from being concentrated and applied to the joint portion 4, it is possible to use a resin having a high thermal expansion coefficient for the covering portion 106.

  The downsizing of the physical quantity sensor and the physical quantity sensor device will be described with reference to FIGS. 10 and 11. The physical quantity sensor 101 is manufactured by processing an SOI substrate and a silicon substrate by a fine processing technique of a semiconductor process. Therefore, in order to prevent damage during handling of the SOI substrate and the silicon substrate, the physical quantity sensor 101 is difficult to downsize in the height direction as compared with the planar downsizing.

  Further, when the supporting base material 102a and the sensitive base material 102b are thinned, the supporting base material 102a and the sensitive base material 102b are easily deformed and easily distorted by a force applied from the outside. As a result, the output of the physical quantity sensor 101 is likely to fluctuate. In the worst case, the physical quantity sensor 101 may be damaged by an externally applied force. This also makes it difficult for the physical quantity sensor 101 to be downsized in the height direction as compared to planar downsizing.

  If the gap 105 is narrowed to reduce the height, the distance between the movable electrode 102f and the fixed electrode 102e, the support base material 102a and the wiring base material 103 is narrowed, and changes depending on the applied acceleration. The capacitance that is not increased, that is, the parasitic capacitance is increased. As a result, detection accuracy may deteriorate due to an increase in output offset. This also makes it difficult for the physical quantity sensor 101 to be downsized in the height direction as compared to planar downsizing.

  However, in the physical quantity sensor 101, when the planar dimension is reduced for miniaturization, the area of the planar view occupied by the movable electrode 102f and the fixed electrode 102e that affect the detection sensitivity and the junction 104 that contributes as a parasitic capacitance. The occupied area in plan view needs to be reduced in a similar manner. Therefore, when the planar dimension of the physical quantity sensor 101 is reduced, it is necessary to reduce the area of the planar view occupied by the joint portion 104.

  For this reason, in order to reduce the planar dimension of the physical quantity sensor 101, the joint 104 has a relatively large force relative to the force that is concentrated due to the thermal stress unless the dimension in the height direction is also reduced accordingly. The strength is weakened. Therefore, when the dimension in the height direction of the physical quantity sensor 101 cannot be reduced, defects such as deformation, peeling, and cracking are likely to occur in the joint portion 104.

  Further, when the joint 104 is deformed, peeled off, cracked, etc., and the joint 104 is displaced, the physical quantity sensor 101 is also deformed. Therefore, the sensitive base material 102b is deformed, and the distance between the movable electrode 102f and the fixed electrode 102e is changed. As a result, an offset may occur in the output of the sensitive base material 102b, or the output of the sensitive base material 102b may fluctuate. Therefore, the physical quantity sensor 101 and the physical quantity sensor device 110 disclosed in Patent Document 1 have a problem that it is difficult to reduce the size.

  Therefore, in the present embodiment, as shown in FIGS. 1 to 4, when reducing the planar dimensions of the physical quantity sensor 1 and the physical quantity sensor device 10, instead of reducing the dimension in the height direction of the physical quantity sensor 1, An inclined surface 2o is formed on the support base 2a. As a result, the thermal stress caused by the temperature fluctuation is suppressed from being concentrated on the joint 4. Therefore, the planar dimension of the physical quantity sensor 1 can be reduced without reducing the height direction dimension of the physical quantity sensor 1.

  Therefore, according to this embodiment, it is possible to provide a physical quantity sensor and a physical quantity sensor device that are excellent in miniaturization.

  FIG. 6 is an explanatory diagram of the moment of force acting on the joint. FIG. 6 will be described with reference to FIG. 4. When the support base 2 a is chamfered to form the chamfered portion 2 o, the moment of force acting on the inner lower end portion 3 w of the joint portion 4 and cutting are performed. The relationship between the extended line 2q dimension of the upper surface 2n or the extended line 2r dimension of the side surface 2p of the cut support base 2a is shown. In FIG. 6 (a), h1 is the dimension of the extension line 2r of the side surface 2p, and w2 in FIG. 6 (b) is the dimension of the extension line 2q of the upper surface 2n. The moment of force shown in FIG. 6 is a relative quantity and is not shown in units.

  FIG. 6 will be described with reference to FIG. 4 when the chamfered portion 2o is formed, but the moment of force generated by the extension line 2q of the upper surface 2n and the extension line 2r of the side surface 2p disappears and is generated by the chamfered portion 2o. A moment of force is generated. Then, when the dimension of the extension line 2q of the upper surface 2n is set to 0, the moment of force generated by the chamfered portion 2o is roughly calculated under the continuous condition that the moment of force generated in the extension line 2r of the side surface 2p is equal. is there.

  As shown in FIGS. 6A and 6B, as the extension line 2q dimension of the upper surface 2n and the extension line 2r dimension of the side surface 2p increase, that is, as the chamfering amount increases, the inner lower end of the joint portion 4 increases. It can be seen that the moment of force acting on the portion 3w is suppressed. The outline of FIG. 6 corresponds to FIG.

  As shown in FIGS. 1 and 2, the side surface of the support base 2a of the present embodiment is formed of an inclined surface 2o and a vertical surface 2z. Therefore, the SOI substrate is cut by using the first dicing blade having a tip portion inclined so that the tip of the blade becomes thin and the second dicing blade having a disk shape with a uniform thickness. The material 2 is cut out. The first dicing blade can also be formed with a flat surface at the most distal portion for wear resistance.

  Since the inclined surface 2o is formed to be inclined with respect to the vertical surface 2z, the thickness of the first dicing blade other than the tip is larger than the thickness of the second dicing blade. Therefore, since the first dicing blade is stronger in strength, the first dicing blade is suppressed from shaking in the direction of the rotation axis during dicing compared to the second dicing blade. Therefore, the first dicing blade can be diced with higher dimensional accuracy than the second dicing blade.

  Therefore, in this embodiment, the SOI substrate is first diced with a dimensional accuracy up to the middle of the thickness direction of the support base 2a by the first dicing blade. Next, the support base material 2a is cut by the second dicing blade, and the sensor base material 2 is cut out. At that time, the SOI substrate is diced so that the second dicing blade is guided to the inclined groove formed by the first dicing blade, so that the sensor base 2 is cut out with high dimensional accuracy.

  Therefore, according to the present embodiment, as shown in FIG. 2, the side surface of the support substrate 2a is composed of the inclined surface 2o and the vertical surface 2z provided below the inclined surface 2o. 2 can be cut out with high dimensional accuracy.

<First Modification>
FIG. 7 is a schematic cross-sectional view of a physical quantity sensor device that is a first modification. In the physical quantity sensor device 10 of this modification, as shown in FIG. 7, the inclined surface 2o is formed from two surfaces having different inclination angles. In the cross-sectional view, the inclined surface 2o of the present modified example has a contour line on the inner side of the virtual contour line of the sensor base material 2 formed from the extension line on the upper surface of the sensor base material 2 and the extension line on the side surface of the sensor base material 2.

  Therefore, by forming the inclined surface 2o of the present modification, it is possible to suppress the deformation of the bonded portion and the occurrence of peeling and cracking at the bonded portion with respect to the thermal stress caused by the temperature fluctuation. As a result, deformation of the sensitive base material due to deformation of the joint portion is suppressed.

  In the present modification, the inclined surface 2o is formed from two surfaces having different inclination angles, but the present invention is not limited to this. The inclined surface 2o can also be formed from two or more surfaces.

<Second Modification>
FIG. 8 is a schematic cross-sectional view of a physical quantity sensor device according to a second modification. In the physical quantity sensor device 10 of the present modified example, as shown in FIG. 8, the contour of the inclined surface 2 o is two line segments parallel to the extension line on the upper surface of the sensor base 2 and the sensor base 2 in the sectional view. Consists of two line segments parallel to the side extension.

  If it is such an aspect, the inclined surface 2o of this modified example is the virtual outline of the sensor base material 2 formed by the extension line of the upper surface of the sensor base material 2 and the extension line of the side surface of the sensor base material 2 in a cross-sectional view. It has a contour line on the inner side.

  Therefore, by forming the inclined surface 2o of the present modification, it is possible to suppress the deformation of the bonded portion and the occurrence of peeling and cracking at the bonded portion with respect to the thermal stress caused by the temperature fluctuation. As a result, deformation of the sensitive base material due to deformation of the joint portion is suppressed.

  In this modification, the outline of the inclined surface 2o has two lines parallel to the extension line on the upper surface of the sensor base material 2 and two lines parallel to the extension line on the side surface of the sensor base material 2 in a sectional view. Although it consists of minutes, it is not limited to this. The profile of the inclined surface 2o is one or more parallel to the extended line on the upper surface of the sensor base 2 and one or two or more parallel to the extended line on the side of the sensor base 2 in a sectional view. It is also possible to consist of

<Third Modification>
FIG. 9 is a schematic cross-sectional view of a physical quantity sensor device according to a third modification. In the physical quantity sensor device 10 of this modification, the inclined surface 2o is a curved surface. Therefore, as shown in FIG. 9, the contour line of the inclined surface 2o is a curved line in a sectional view.

  If it is such an aspect, the inclined surface 2o of this modified example is the virtual outline of the sensor base material 2 formed by the extension line of the upper surface of the sensor base material 2 and the extension line of the side surface of the sensor base material 2 in a cross-sectional view. It has a contour line on the inner side.

  Therefore, by forming the inclined surface 2o of the present modification, it is possible to suppress the deformation of the bonded portion and the occurrence of peeling and cracking at the bonded portion with respect to the thermal stress caused by the temperature fluctuation. As a result, deformation of the sensitive base material due to deformation of the joint portion is suppressed.

DESCRIPTION OF SYMBOLS 1 Physical quantity sensor 2 Sensor base material 2a Support base material 2b Sensing base material 2c, 2d Oxide insulating layer 2e Fixed electrode 2f Movable electrode 2g Conductive layer 2h Frame body layer 2i 1st connection metal layer 2j 1st sealing metal layer 2o Chamfered portion, inclined surface 3 wiring substrate 3a silicon substrate 3c insulating layer 3i second connection metal layer 3j second sealing metal layer 3k wiring layer 3m pad electrode 4 bonding portion 4a bonding layer 5 gap 6 covering portion 7 package 10 Physical quantity sensor device

Claims (11)

A sensor substrate for detecting physical quantities;
A wiring substrate bonded to the sensor substrate;
A joint for joining the sensor base and the wiring base;
Have
The sensor base material is disposed on the upper side of the wiring base material, has an upper surface and a side surface, and the joint portion has a smaller width dimension than the sensor base material and the wiring base material in a sectional view. Because
A physical quantity sensor, wherein a chamfered portion having a contour line inside a virtual contour line formed from an extension line of the upper surface and an extension line of the side surface is formed on the sensor base material in a cross-sectional view. A sensor substrate for detecting physical quantities;
A wiring substrate bonded to the sensor substrate;
A joint for joining the sensor base and the wiring base;
A covering portion for covering the sensor substrate;
Have
The sensor base material is disposed on the upper side of the wiring base material, has an upper surface and a side surface, and the joint portion has a smaller width dimension than the sensor base material and the wiring base material in a sectional view. A device,
The sensor substrate has a chamfered portion having a contour line inside a virtual contour line formed from an extension line of the upper surface and an extension line of the side surface in a cross-sectional view, and an elastic modulus of the covering portion Is smaller than the elastic modulus of the sensor substrate.   The physical quantity sensor device according to claim 2, wherein the chamfered portion is an inclined surface inclined from the upper surface to the side surface.   The physical quantity sensor device according to claim 3, wherein an angle of the inclined surface inclined from an extended line of the side surface is 35 ° to 55 °.   The physical quantity sensor device according to claim 3, wherein the inclined surface includes a plurality of surfaces having different inclination angles.   The contour line of the chamfered portion includes at least one line segment parallel to the extension line of the upper surface and at least one line segment parallel to the extension line of the side surface in a cross-sectional view. The physical quantity sensor device described.   The physical quantity sensor device according to claim 2, wherein the chamfered portion is a curved surface.   The physical quantity sensor device according to any one of claims 2 to 7, wherein the side surface includes the chamfered portion and a vertical surface continuously provided below the chamfered portion.   The physical quantity sensor device according to any one of claims 2 to 8, wherein the chamfered portion overlaps with the joint portion in a plan view. The sensor substrate comprises a sensitive substrate that detects a physical quantity, and a support substrate that supports the sensitive substrate,
The physical quantity sensor device according to any one of claims 2 to 9, wherein a vertical dimension of the support base material is larger than a vertical dimension of the sensitive base material.   The physical quantity sensor device according to any one of claims 2 to 10, wherein the covering portion is made of a silicone resin or a fluorine resin.