JP2010216834A - Sensor for detecting dynamic quantity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor for detecting the dynamic quantity which enables suppression of the nonuniformity in sensor sensitivity caused by a working process and consequent improvement of a yield in manufacturing. <P>SOLUTION: The sensor for detecting the dynamic quantity includes a first substrate 2 which supports a displacement part 12 inside a frame 11 by beams 13 so that the displacement part can rock, a second substrate 3 wherein a support 21 having an opening 23 and a weight 22 being connected with the displacement part 12 are formed, and detecting elements 17 which output signals according to the dynamic quantity on the basis of the amount of deflection of the beams 13. In a plane view, the first substrate 2 and the second substrate 3 are so constituted that at least portions of connection with the beams 13 at the inner edge 11a of the frame 11 are positioned outside the opening edge 21a of the support 21 and that at least portions of connection with the beams 13 at the outer edge 12a of the displacement part 12 are positioned inside the outer edge 22a of the weight 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a mechanical quantity detection sensor capable of detecting acceleration in three axial directions of an X axis, a Y axis, and a Z axis that are orthogonal to each other.

  In the automobile industry and the machine industry, there is an increasing demand for small mechanical quantity detection sensors that can accurately detect acceleration. As such a mechanical quantity detection sensor, an acceleration sensor that can simultaneously detect accelerations in three axial directions orthogonal to each other is known (see, for example, Patent Document 1). This acceleration sensor is formed by etching a three-layer SOI substrate obtained by bonding a first semiconductor substrate made of silicon, an insulating layer made of silicon oxide, and a second semiconductor substrate made of silicon.

  The first semiconductor substrate is formed with a frame body by etching, a displacement portion located at the center of the frame body, and a beam portion continuous from the four sides of the frame body to the displacement portion, and the second semiconductor substrate by frame etching. A support part joined to the body and a weight part joined to the displacement part are formed. In addition, a detection element is disposed on the upper surface of each beam portion, and an inertial force acts on the weight portion to cause each beam portion to bend and deform, thereby detecting acceleration in three axes.

JP 2007-322300 A

  However, since the mechanical quantity detection sensor described in Patent Document 1 is formed by etching from the front surface and the back surface of the SOI substrate, alignment deviation occurs between the frame body and the support portion, and the displacement portion and the weight portion. It was. That is, it is difficult to finely adjust the etching rate. For example, a step is formed so that the support part protrudes from the frame body in part, and conversely, in the other part, the frame is opposed to the support part. A step was formed so that the body protruded.

  Due to such misalignment, the range that functions as a spring in the first semiconductor substrate varies, and therefore, there is a problem that the sensor sensitivity varies and the manufacturing yield decreases. In particular, in plan view, when the opening edge of the support part is located outside the inner edge of the frame body, or when the outer edge of the weight part is located outside the outer edge of the displacement part, the part that originally does not function as a spring Since it functions as a spring, variations in sensor sensitivity have been large.

  Further, in the mechanical quantity detection sensor formed by such a machining process, the corners of the beam side surface and the inner side surface of the frame body, and the corners of the beam side surface and the outer side surface of the weight portion are R-shaped. Since the stress value at the connecting portion of the beam portion also changes in accordance with the curvature of the R shape, the sensitivity of the sensor varies and the manufacturing yield decreases.

  The present invention has been made in view of this point, and an object of the present invention is to provide a mechanical quantity detection sensor that can suppress variations in sensor sensitivity due to a machining process and can improve the manufacturing yield.

  The mechanical quantity detection sensor of the present invention includes a first frame body, a displacement portion positioned inside the frame body, and a beam portion that supports the displacement portion so as to be swingable with respect to the frame body. A substrate, a support having an opening, connected to the frame, and a weight connected to the displacement; and a second substrate stacked on the first substrate; A detection element that outputs a signal corresponding to a mechanical quantity based on a deflection amount of the beam portion, and the first substrate and the second substrate are at least the beam portion at an inner edge of the frame body in a plan view. A first positional relationship in which the connecting portion is located outside the opening edge of the support portion and / or a connecting portion with the beam portion at least at the outer edge of the displacement portion is located inside the outer edge of the weight portion. The positional relationship of 2 is taken.

  According to this configuration, even if alignment misalignment occurs, a step is formed so that the support portion always protrudes from the frame body at the base portion of the beam portion, and the weight portion protrudes from the displacement portion. Since the step is formed in the first substrate, it is possible to reduce the variation of the range functioning as a spring in the first substrate, suppress the variation of the sensor sensitivity, and improve the manufacturing yield. In particular, in plan view, it is possible to prevent a part of the frame body that originally does not function as a spring and a part of the displacement portion from functioning as a spring. Further, even if corners of the side surface of the beam portion and the inner side surface of the frame body and the outer surface of the displacement portion are processed into an R shape, the influence of the stress value due to the difference in the curvature of the R shape is reduced, and the sensor sensitivity The manufacturing yield can be improved by suppressing the variation of the above.

  In the mechanical quantity detection sensor according to the present invention, the inner edge of the frame body is located outside the opening edge of the support portion and the outer edge of the displacement portion is located inside the outer edge of the weight portion in plan view. It is characterized by.

  According to this configuration, the connection portion between the frame body and the beam portion is positioned outside the opening edge of the support portion and the connection portion between the displacement portion and the beam portion is positioned on the outer edge of the weight portion in a plan view with easy processing. It can be located inside.

  In the mechanical quantity detection sensor according to the present invention, a corner portion formed by an inner surface forming the opening portion of the support portion and a connection surface connected to the frame body of the support portion is chamfered. It is characterized by.

  According to this configuration, since the load generated in the beam portion is distributed in the chamfered portion of the support portion, stress concentration on the beam portion can be prevented and damage to the beam portion due to impact can be prevented. Further, damage due to the collision between the beam portion and the support portion can be reduced.

  In the mechanical quantity detection sensor according to the present invention, a corner portion formed by an outer surface of the weight portion and a connection surface connected to the displacement portion of the weight portion is chamfered.

  According to this configuration, since the load generated in the beam portion is distributed in the chamfered portion of the weight portion, stress concentration on the beam portion can be prevented, and damage to the beam portion due to impact can be prevented. Further, damage due to collision between the beam portion and the weight portion can be reduced.

  In the mechanical quantity detection sensor according to the present invention, the chamfer is chamfered into a curved surface.

  According to this configuration, chamfering can be easily performed by etching.

  In the mechanical quantity detection sensor according to the present invention, the first substrate and the second substrate are laminated via an insulating layer, and the beam portion includes the first substrate and the insulating layer. It is formed in a laminated state.

  According to this configuration, since the beam portion is formed with the insulating layer remaining, stress concentrates directly on the beam portion due to the reaction force from the corner portion supporting the beam portion in the support portion or the weight portion. Can be prevented, and damage to the beam portion can be prevented. In addition, by leaving the insulating layer, it is possible to reduce the change in the spring constant according to the variation in the processing amount due to the removal of the insulating layer, and to suppress the variation in the sensor sensitivity, thereby improving the manufacturing yield.

  In the mechanical quantity detection sensor according to the present invention, the side surface of the beam portion and the inner side surface of the support portion intersect at a right angle in plan view on the frame body side of the beam portion.

  According to this configuration, since the side surface of the beam portion and the inner side surface of the support portion intersect at a right angle in plan view on the frame body side of the beam portion, the sensor sensitivity caused by the variation in the curvature of the R shape of the base portion on the frame body side. Variations can be suppressed and the manufacturing yield can be improved.

  The present invention is characterized in that, in the mechanical quantity detection sensor, a side surface of the beam portion and an outer surface of the weight portion intersect at a right angle in a plan view on the displacement body side of the beam portion.

  According to this configuration, since the side surface of the beam portion and the outer surface of the weight portion intersect at a right angle in plan view on the displacement body side of the beam portion, the sensor sensitivity due to the variation in the curvature of the R shape of the base portion on the displacement portion side. It is possible to improve the manufacturing yield by suppressing the variation of the above.

  In the mechanical quantity detection sensor according to the present invention, the detection element is a piezoelectric element.

  According to this configuration, the detection element can be configured with a simple configuration.

  According to the present invention, it is possible to improve the manufacturing yield by suppressing variations in sensor sensitivity due to the machining process.

It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, and is a perspective view of a mechanical quantity detection sensor. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, and is an exploded perspective view of a mechanical quantity detection sensor. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, and is an upper surface schematic diagram of a mechanical quantity detection sensor. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, (a) is a cross-sectional schematic diagram which follows the AA line of FIG. 3, (b) is a cross-sectional schematic diagram which follows the BB line of FIG. FIG. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, (a) is detection explanatory drawing of the mechanical quantity detection sensor when a weight part rotates around an X-axis, (b) is a figure. It is explanatory drawing of detection operation | movement of the mechanical quantity detection sensor at the time of a weight part linearly moving in a Z-axis direction. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, and is a figure for demonstrating an example of a process. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, and is an upper surface schematic diagram of the mechanical quantity detection sensor for a test. It is a figure which shows embodiment of the mechanical quantity detection sensor which concerns on this invention, and is an output voltage result of the mechanical quantity detection sensor used in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a mechanical quantity detection sensor according to an embodiment of the present invention. FIG. 2 is an exploded perspective view of the mechanical quantity detection sensor according to the embodiment of the present invention.

  As shown in FIGS. 1 and 2, the mechanical quantity detection sensor 1 is configured by bonding a first semiconductor substrate 2 and a second semiconductor substrate 3 via an insulating layer 4. The mechanical quantity detection sensor 1 is, for example, an SOI (Silicon On Insulator) substrate having a three-layer structure in which a first semiconductor substrate 2 is a silicon layer, an insulating layer 4 is a silicon oxide layer, and a second semiconductor substrate 3 is a silicon layer. Can be manufactured.

  The first semiconductor substrate 2 includes a relatively thin plate-like silicon layer as compared with the second semiconductor substrate 3, and a rectangular frame-shaped frame body 11 and a displacement disposed inside the frame body 11. The part 12 and the four beam parts 13 which connect the four sides of the frame 11 and the displacement part 12 are formed. The frame body 11, the displacement portion 12, and the beam portion 13 are formed by providing four openings that are L-shaped in top view around the displacement portion 12 by etching the first semiconductor substrate 2.

  The frame 11 is formed so as to surround the displacement portion 12 by four L-shaped openings. The displacement part 12 is formed in a substantially square shape, and is disposed in the center of the frame 11. Each of the four beam portions 13 includes a long portion 15 extending from one side of the frame 11 toward the opposite side, and a short portion 16 connected to the four corners of the displacement portion 12 connected to the long portion 15. Is done. Thus, since the four beam parts 13 have the elongate part 15, they become the structure which is easy to bend.

  On the upper surface of each beam portion 13, detection elements 17 are provided at positions where they are connected to the frame body 11, and the deflection amount of each beam portion 13 is detected by this detection element 17. The detection element 17 is a so-called piezoelectric element, and is formed by depositing the lower electrode 25, the piezoelectric film 26, and the upper electrode 27 in this order on the upper surface of a base film not shown (see FIG. 4). The detection element 17 is deformed by the bending generated in the beam portion 13, and the pressure generated by the deformation is converted into a voltage and output.

  The second semiconductor substrate 3 is composed of a relatively thick silicon layer compared to the first semiconductor substrate 2, and has a support portion 21 having a rectangular opening 23 and an inner side of the opening 23. The weight part 22 arrange | positioned in this is formed. The support portion 21 and the weight portion 22 are formed by providing a rectangular frame-shaped opening around the weight portion 22 by etching the first semiconductor substrate 2.

  The support portion 21 has a shape corresponding to the frame body 11 in a top view, and is joined to the lower surface of the frame body 11 via the insulating layer 4. The weight portion 22 is formed in a substantially rectangular parallelepiped shape, and is joined to the lower surface of the displacement portion 12 via the insulating layer 4. Thus, the weight portion 22 is supported by the four beam portions 13 via the displacement portion 12 so as to be swingable inside the opening portion 23 of the support portion 21. Therefore, when an inertial force acts on the position of the center of gravity of the weight portion 22, rotation about the X axis, rotation about the Y axis, and linear movement in the Z axis direction are possible.

  Next, with reference to FIG. 3 and FIG. 4, the bonding state of the first semiconductor substrate and the second semiconductor substrate will be described in detail. FIG. 3 is a schematic top view of the mechanical quantity detection sensor according to the embodiment of the present invention. 4A and 4B are schematic cross-sectional views of FIG. 3. FIG. 4A is a schematic cross-sectional view taken along the line AA, and FIG. 4B is a schematic cross-sectional view taken along the line BB.

  As shown in FIG. 3, each side of the inner edge 11 a of the frame body 11 is formed in parallel with each side of the outer edge 12 a of the displacement portion 12, and faces each side of the inner edge 11 a of the frame body 11. The distance to each side of the outer edge 12a of the displacement part 12 is formed to be the same. Further, each side of the opening edge 21 a of the support portion 21 is formed in parallel to each side of the outer edge 22 a of the weight portion 22, and the weight portion 22 facing from each side of the opening edge 21 a of the support portion 21. The distance to each side of the outer edge 22a is the same. At this time, the outer edge 22a of the weight portion 22 facing from each side of the opening edge 21a of the support portion 21 is larger than the distance from each side of the inner edge 11a of the frame 11 to each side of the outer edge 12a of the opposing displacement portion 12. The distance to each side is shorter.

  Therefore, since the inner edge 11a of the frame 11 is positioned outside the opening edge 21a of the support portion 21, a step is formed so as to expose the opening edge 21a of the support portion 21. With this configuration, the connection portion of the inner edge 11a of the frame body 11 with the beam portion 13 is located outside the opening edge 21a of the support portion 21, so that the alignment deviation due to the machining process is not caused between the frame body 11 and the support portion 21. Even if it occurs, a step is formed so that the support portion 21 always protrudes from the frame body 11, so that a part of the beam portion 13 becomes a fulcrum at the time of swinging, and a part of the frame body 11 is It does not become a fulcrum when swinging.

  Similarly, since the outer edge 12a of the displacement part 12 is located inside the outer edge 22a of the weight part 22, a step is formed so as to expose the outer edge 22a of the weight part 22. With this configuration, the connection portion of the outer edge 12a of the displacement portion 12 with the beam portion 13 is located inside the outer edge 22a of the weight portion 22, and therefore, an alignment shift due to the machining process occurs between the displacement portion 12 and the weight portion 22. Even in this case, a step is formed so that the weight portion 22 always protrudes from the displacement portion 12, so that a part of the beam portion 13 serves as a fulcrum when swinging, and a portion of the displacement portion 12 swings. It will not be a fulcrum when moving.

  As described above, since the frame body 11 and the displacement portion 12 do not become a fulcrum when swinging due to the misalignment, it is reliably prevented that a part of the frame body 11 or a part of the displacement portion 12 functions as a spring. In addition, variations in sensor sensitivity can be suppressed. The step formed by the frame 11 and the support portion 21 and the protrusion length of the step formed by the displacement portion 12 and the weight portion 22 are designed to be about 10 μm in consideration of an alignment shift of about 5 μm. Yes.

  As shown in FIG. 4A, a curved chamfered portion is formed at a corner portion formed by the inner surface 21 b that forms the opening 23 of the support portion 21 and the joint surface 21 c that is joined to the frame body 11. 21d is formed. Similarly, a curved chamfered portion 22 d is also formed at a corner portion formed by the outer surface 22 b of the weight portion 22 and the joint surface 22 c joined to the displacement portion 12. As described above, since the support portion 21 and the weight portion 22 are chamfered, even if the beam portion 13 swings greatly in the direction of the arrow due to an impact and collides with the support portion 21 and the weight portion 22, damage to the beam portion 13 is caused. Can be reduced.

  Further, as shown in FIGS. 4A and 4B, the beam portion 13 is supported by the chamfered portions 21d and 22d at the time of swinging at the connection portion with the frame body 11 and the connection portion with the displacement portion. Is done. With this configuration, since the load generated in the beam portion 13 is distributed in the chamfered portions 21d and 22d, stress concentration on the beam portion 13 can be prevented, and damage to the beam portion 13 due to impact can be prevented. In the present embodiment, the chamfered portions 21d and 22d are formed with curved surfaces. However, the present invention is not limited to this configuration, and any configuration can be used as long as the load acting on the beam portion 13 can be distributed. It is good also as a structure formed with an inclined surface.

  Further, the beam portion 13 is formed with the insulating layer 4 left. With this configuration, it is possible to prevent stress from being concentrated directly on the beam portion 13 due to the reaction force received from the support portion 21 and the weight portion 22, and to prevent the beam portion 13 from being damaged. Further, by leaving the insulating layer 4, it is possible to reduce the change in the spring constant corresponding to the variation in the processing amount due to the removal of the insulating layer 4 and to suppress the variation in the sensor sensitivity. Note that the machining process of the beam portion 13 will be described later together with the machining process of the mechanical quantity detection sensor 1.

  Returning to FIG. 3, the frame body 11 side of the long portion 15 of the beam portion 13 is supported by the step of the support portion 21, and both side surfaces 15 a of the long portion 15 of the beam portion 13 in the plan view are respectively the support portions 21. It is orthogonal to the inner surface 21a. Further, the displacement portion 12 side of the short portion 16 of the beam portion 13 is in contact with the step of the weight portion 22, and both side surfaces 16 a of the short portion 16 of the beam portion 13 are orthogonal to the outer surface 22 a of the weight portion 22 in plan view. ing. In this way, the beam portion 13 is swung around the position where both side surfaces are perpendicular to the inner side surface 21a of the support portion 21 and the outer side surface 22a of the weight portion 22 and avoid the root portion at both ends. It is possible to suppress variations in sensor sensitivity due to variations in the curvature of the R shape at the base portion of the portion 13.

  Next, the operation of the mechanical quantity detection sensor will be briefly described with reference to FIG. 5A and 5B are explanatory diagrams of detection operation of the mechanical quantity detection sensor. FIG. 5A is an explanatory diagram of detection operation when the weight portion rotates around the X axis, and FIG. 5B is an explanatory diagram of the weight portion in the Z axis direction. It is detection operation explanatory drawing at the time of linear motion.

  As shown in FIG. 5A, when acceleration acts on the mechanical quantity detection sensor 1 and an inertial force acts on the weight part 22 in the Y-axis direction, the weight part 22 rotates about the X-axis. . At this time, the displacement portion 12 side of the beam portions 13a, b moves downward in the Z-axis direction, and a force acts upward in the Z direction on the frame body 11 side of the beam portions 13a, b. Further, the displacement portion 12 side of the beam portions 13c and d moves upward in the Z-axis direction, and a force acts downward in the Z-axis direction on the frame body 11 side of the beam portions 13c and d. The frame 11 side of the beams 13a and 13b is bent so as to swell upward in the Z-axis direction, and the frame 11 side of the beams 13c and d is bent so as to be recessed downward in the Z-axis direction.

  The detection elements 17a and 17b are deformed so as to swell upward in the Z-axis direction in accordance with the bending of the beam portions 13a and b on the frame body 11 side, and output a voltage corresponding to the deformation. The detection elements 17c and d are deformed so as to be recessed downward in the Z-axis direction in accordance with the bending of the beam portions 13c and d on the frame body 11 side, and output a voltage corresponding to the deformation. The voltages output from the detection elements 17a, b, c, and d are calculated by an arithmetic circuit (not shown) to calculate acceleration.

  When the weight portion 22 rotates about the Y axis, conversely, a force acts downward in the Z-axis direction on the frame 11 side of the beam portions 13a, b, and the frame 11 of the beam portions 13c, d. A force acts upward in the Z-axis direction. Therefore, the detection elements 17a and b are deformed so as to be recessed downward in the Z-axis direction in accordance with the bending of the beam portions 13a and b on the frame body 11 side, and the detection elements 17c and d are respectively formed on the beam portions 13c and d. It deforms so as to swell upward in the Z-axis direction in accordance with the bending on the frame body 11 side.

  As shown in FIG. 5B, when acceleration acts on the mechanical quantity detection sensor 1 and an inertial force acts on the weight part 22 in the Z-axis direction downward, the weight part 22 moves linearly in the Z-direction downward. To do. At this time, the displacement part 12 side of the beam parts 13a, b, c, and d moves downward in the Z-axis direction, and a force acts on the frame body 11 side of the beam parts 13a, b, c, and d in the Z-axis direction upward. . The frame 11 side of the beam portions 13a, b, c, and d bends so as to expand upward in the Z-axis direction, and the detection elements 17a, b, c, and d also deform so as to expand upward in the Z-axis direction. And the voltage output from each detection element 17a, b, c, d is calculated in the arithmetic circuit which is not shown in figure, and an acceleration is calculated.

  In the mechanical quantity detection sensor 1, the mass of the weight portion 22 and the displacement portion 12, the spring constant of each beam portion 13, the step between the frame 11 and the support portion 21, and the distance between the displacement portion 12 and the weight portion 22. It is also possible to arbitrarily adjust the sensor sensitivity by appropriately changing the protruding length of the step.

  Hereinafter, an example of the machining process of the mechanical quantity detection sensor will be described with reference to FIG. FIG. 6 is a diagram for explaining an example of the machining process according to the embodiment of the present invention.

  As shown in FIG. 6A, an SOI substrate in which the first semiconductor substrate 2, the insulating layer 4, and the second semiconductor substrate 3 are stacked is prepared, and a support substrate 31 is disposed on the upper surface of the first semiconductor substrate 2. Is done. Next, as shown in FIG. 6B, the lower surface of the second semiconductor substrate 3 is polished and thinned, and the second semiconductor substrate 3 is processed by photolithography and etching to form the support portion 21 and the weight. Part 22 is formed. At this time, the corner formed by the inner surface 21b of the support portion 21 and the bonding surface 21c on the first semiconductor substrate 2 side, and the outer surface 22b of the weight portion 22 and the bonding surface 22c on the first semiconductor substrate 2 side are formed. And the corner formed by chamfering is chamfered (see FIG. 4).

  In the present embodiment, the chamfered portions 21d and 22d are formed by adjusting the etching conditions so that the over edge advances in the vicinity of the boundary portion between the support portion 21 and the weight portion 22 and the insulating layer 4. However, any configuration is possible as long as the chamfered portions 21d and 22d can be formed. Further, the chamfering creates gaps between the support portion 21 and the frame body 11 and between the weight portion 22 and the displacement portion 12 at the corners of the support portion 21 and the weight portion 22 on the insulating layer 4 side. This indicates that the processing method is not limited.

  Next, as shown in FIG. 6C, the base substrate 32 is processed by photolithography and etching to form a cavity 33 and bonded to the lower surface of the second semiconductor substrate 3. Next, as shown in FIG. 6D, the support substrate 31 is peeled from the upper surface of the first semiconductor substrate 2, and the upper surface of the first semiconductor substrate 2 is polished and thinned to a desired thickness. Next, as shown in FIG. 6E, a metal material and a piezoelectric material are deposited on the upper surface of the first semiconductor substrate 2 by sputtering, and patterning is performed by photolithography and etching to form the detection element 17. .

  Next, as shown in FIG. 6F, the first semiconductor substrate 2 and the insulating layer 4 are processed by photolithography and etching to form the frame body 11, the beam portion 13, and the displacement portion 12. At this time, the insulating layer 4 bonded to the beam portion 13 remains without being removed by etching. In this way, the mechanical quantity detection sensor 1 shown in FIG. 1 can be obtained.

  Here, with reference to FIG. 7 and FIG. 8, the test carried out by the applicant of the present application in order to verify the variation in sensor sensitivity due to the provision of a step between the frame and the support will be described. In this test, variations in sensor sensitivity are verified by comparing output voltage results based on the presence or absence of an R shape at the base of the beam.

  FIG. 7 is a schematic top view of a mechanical quantity detection sensor for testing, where (a) has an R shape without a step, (b) has no R shape without a step, and (c) has an R shape with a step. , (D) respectively show a mechanical quantity detection sensor with a step and without an R shape. FIG. 8 shows an output voltage result of the mechanical quantity detection sensor used in FIG. In the test, a single beam structure mechanical quantity detection sensor is used. First, a single beam structure mechanical quantity detection sensor will be briefly described.

  As shown in FIG. 7A, in the mechanical quantity detection sensor having a single beam structure, the displacement portion 43 and the weight portion 44 are supported by one beam portion 45. The beam portion 45 includes a long portion 48 connected to the frame 42 at one end side, a middle portion 47 connected at one end side to the other end side of the long portion 48, and one end at the other end side of the intermediate portion 47. The short side portion 46 is connected to the displacement portion 43 and the other end side is connected to the displacement portion 43. A first detection element 51 is provided on the frame portion 42 side of the long portion 48, a second detection element 52 is provided at an intermediate position of the long portion 48, and a third detection element 53 is provided at an intermediate position of the intermediate length portion 47. Each is arranged.

  Further, in the base portion of the beam portion 45, the corner portion 55 between the side surface of the beam portion 45 and the inner side surface of the frame body 42 has an R shape, and the frame body 42 and the support portion 41 are formed flush with each other. 7B is different from FIG. 7A only in that the corner portion 56 between the side surface of the beam portion 45 and the inner side surface of the frame body 42 has a right-angle shape in the root portion of the beam portion 45. FIG. 7C is different from FIG. 7A only in that a step is formed between the frame body 42 and the support portion 41. FIG. 7 (d) shows that the corner portion 56 between the side surface of the beam portion 45 and the inner side surface of the frame body 42 has a right-angle shape in FIG. 7 (a) and the base portion of the beam portion 45 and the frame body 42 and the support portion. The difference is only in that a step is formed with 41.

When an acceleration of 1 G (9.8 m / s ² ) is applied to the mechanical quantity detection sensor configured as described above in the X-axis direction, the Y-axis direction, and the Z-axis direction, an output voltage result as shown in FIG. 8 is obtained. can get. First, a case where no step is provided between the frame body 42 and the support portion 41 will be described. As shown in FIG. 8A, when acceleration is applied in the Z-axis direction, an output voltage of 0.555 V is generated in the first detection element 51 for the mechanical quantity detection sensor shown in FIG. For the mechanical quantity detection sensor shown in FIG. 7B, an output voltage of 0.584v is generated. That is, the sensor sensitivity varies by about 5% depending on the presence or absence of the R shape at the base portion of the beam portion 45.

  On the other hand, when a step is provided between the frame body 42 and the support portion 41, as shown in FIG. 8B, when acceleration is applied in the Z-axis direction, the dynamics shown in FIG. For the quantity detection sensor, an output voltage of 0.566v is generated in the first detection element 51, and for the mechanical quantity detection sensor shown in FIG. 7 (d), an output voltage of 0.569v is generated. That is, variation in sensor sensitivity of about 0.4% occurs depending on the presence or absence of the R shape of the base portion of the beam portion 45.

  As described above, when the step is provided between the frame body 42 and the support portion 41, the sensor sensitivity variation due to the presence or absence of the R shape of the base portion of the beam portion 45 is 1 as compared with the case where the step is not provided. / 10 or less can be suppressed.

  As described above, according to the mechanical quantity detection sensor 1 according to the present embodiment, the support portion 21 always protrudes from the frame body 11 at the base portion of the beam portion 13 even when alignment misalignment occurs. Since the step is formed so that the weight portion 22 protrudes from the displacement portion 12, the variation in the range functioning as a spring in the first semiconductor substrate 2 is reduced, and the variation in sensor sensitivity is reduced. It is possible to suppress the manufacturing yield and improve the manufacturing yield. In particular, it is possible to prevent part of the frame 11 that originally does not function as a spring or part of the displacement portion 12 from functioning as a spring. Furthermore, even if the corners of the side surface of the beam portion 13 and the inner side surface of the frame body 11 are processed into an R shape, the influence of the stress value due to the difference in the curvature of the R shape is reduced, thereby suppressing variations in sensor sensitivity. Thus, it is possible to improve the manufacturing yield.

  In the above-described embodiment, the four-beam structure mechanical quantity detection sensor has been described as an example. However, the present invention is not limited to this configuration. Any configuration may be used as long as the weight portion is supported by the beam. For example, the shape of the weight portion and the shape and quantity of the beam portion are not limited.

  In the above-described embodiment, the piezoelectric element is exemplified as the detection element. However, the present invention is not limited to this configuration. Any structure that outputs a signal corresponding to the mechanical quantity based on the deflection of the beam portion may be used. For example, a piezoelectric element may be used instead of the piezoelectric element.

  In the above-described embodiment, the step is formed over the entire periphery of the inner edge of the frame and the opening edge of the support portion. However, the present invention is not limited to this configuration. It is sufficient that a step is formed at least corresponding to the connection portion between the frame and the beam portion. Similarly, it is not necessary to form a step over the entire circumference of the outer edge of the displacement portion and the outer edge of the weight portion, and it is sufficient that a step is formed at least corresponding to the connection portion between the displacement portion and the beam portion.

  In the above-described embodiment, the step is formed between the frame body and the support part and between the displacement part and the weight part. However, the step is formed only on one of the parts. It may be. Further, the chamfered portion may be formed on only one of the support portion and the weight portion. Furthermore, it is good also as a structure by which only any one of the root part of a frame and a beam part and the root part of a displacement part and a beam part is formed in a right-angled shape.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims for patent.

  As described above, the present invention has an effect that it is possible to improve the manufacturing yield by suppressing variations in sensor sensitivity due to the machining process, and in particular, the X axis, the Y axis, and the Z axis orthogonal to each other. This is useful for a mechanical quantity detection sensor that detects acceleration in three axial directions.

DESCRIPTION OF SYMBOLS 1 Mechanical quantity detection sensor 2 1st semiconductor substrate (1st board | substrate)
3 Second semiconductor substrate (second substrate)
4 Insulating layer 11 Frame 11a Inner edge 12 Displacement part 12a Outer edge 13 Beam part 17 Detection element 21 Support part 21a Opening edge 22 Weight part 22a Outer edge 21d, 22d Chamfering part 23 Opening part

Claims (9)

A first substrate formed with a frame, a displacement portion located inside the frame, and a beam portion that swingably supports the displacement portion with respect to the frame;
A second substrate having an opening and formed with a support portion connected to the frame body and a weight portion connected to the displacement portion and stacked on the first substrate;
A detection element that outputs a signal corresponding to a mechanical quantity based on the deflection amount of the beam portion;
In plan view, the first substrate and the second substrate have a first positional relationship in which at least a connection portion with the beam portion at the inner edge of the frame body is located outside the opening edge of the support portion, and / or Or at least the connection part with the said beam part in the outer edge of the said displacement part takes the 2nd positional relationship located inside the outer edge of the said weight part, The mechanical quantity detection sensor characterized by the above-mentioned.   2. The mechanics according to claim 1, wherein the inner edge of the frame body is located outside the opening edge of the support portion and the outer edge of the displacement portion is located inside the outer edge of the weight portion in plan view. Quantity detection sensor.   The corner part formed by the inner surface which forms the said opening part of the said support part, and the connection surface connected to the said frame of the said support part is chamfered, The Claim 1 or Claim 2 characterized by the above-mentioned. The mechanical quantity detection sensor described in 1.   The corner formed by the outer surface of the weight part and the connection surface connected to the displacement part of the weight part is chamfered. Mechanical quantity detection sensor.   The mechanical quantity detection sensor according to claim 3, wherein the chamfer is chamfered in a curved shape. The first substrate and the second substrate are stacked via an insulating layer,
The mechanical quantity detection sensor according to claim 1, wherein the beam portion is formed in a state where the first substrate and the insulating layer are stacked.   The mechanical quantity detection sensor according to claim 1, wherein a side surface of the beam portion and an inner side surface of the support portion intersect at a right angle in a plan view on the frame body side of the beam portion. .   The mechanical quantity detection sensor according to any one of claims 1 to 7, wherein a side surface of the beam portion and an outer surface of the weight portion intersect at a right angle in a plan view on the displacement body side of the beam portion. .   The mechanical quantity detection sensor according to claim 1, wherein the detection element is a piezoelectric element.

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