JP5065356B2 - Semiconductor acceleration sensor - Google Patents

Description

  The present invention relates to a semiconductor acceleration sensor.

  FIG. 1 on page 6 of Japanese Patent No. 3290047 (Patent Document 1) discloses a semiconductor acceleration sensor having a configuration in which a part of a weight is arranged in the internal space of the acceleration sensor main body. In this semiconductor acceleration sensor, the mass of the weight is increased by forming the inner peripheral surface of the support portion surrounding the internal space and the outer peripheral surface of the weight as inclined surfaces arranged in parallel.

Japanese Patent No. 3290047 (page 6, FIG. 1)

  However, in such a semiconductor acceleration sensor, when acceleration in the direction toward the semiconductor sensor element main body (acceleration in the vertical axis direction) is applied to the weight with increased weight, the movement of the weight is regulated. There is no contrivance to prevent the flexible portion of the element from being damaged. Therefore, when a large acceleration is applied to the weight having increased weight, there is a problem that the semiconductor sensor element is damaged. In addition, in this conventional acceleration sensor, a complicated manufacturing process is required in order to obtain parallelism between the inner peripheral surface of the semiconductor sensor element and the outer peripheral surface of the weight and to match the center of the semiconductor sensor element and the weight. I needed it.

  An object of the present invention is to provide a semiconductor acceleration sensor in which even if the weight of the weight is increased by disposing at least a part of the weight in the internal space of the semiconductor sensor element, the semiconductor sensor element is not damaged. It is in.

  Another object of the present invention is to provide a semiconductor acceleration sensor that does not require positioning of a weight with respect to a support portion of the acceleration sensor body using a complicated manufacturing process.

  Another object of the present invention is to provide a semiconductor capable of reducing the variation in performance by reducing the displacement of the displacement of the weight toward the flexible portion even if a dimensional error in manufacturing the support portion or the weight occurs. It is to provide an acceleration sensor.

  Another object of the present invention is to provide a semiconductor acceleration sensor capable of easily and accurately centering a weight with respect to an acceleration sensor body and a method for manufacturing the same.

  A semiconductor acceleration sensor to be improved by the present invention is formed by etching a semiconductor crystal substrate, a weight fixing portion is located at the center, a cylindrical support portion is located at the outer periphery, and the weight A semiconductor sensor body having a flexible part having flexibility between the fixing part and the support part, an acceleration sensor element formed by diffusing resistance in the flexible part, and the center of the weight fixing part And a weight fixed so that the center is positioned on a center line extending in a direction orthogonal to the direction in which the flexible portion extends. In the present invention, the inner peripheral surface of the support portion is configured by annularly combining four trapezoidal inclined surfaces having substantially the same shape so as to follow the outer peripheral surface of the truncated pyramid internal space. . The weight has a linear contact portion that contacts the inner peripheral surface of the support portion when the weight is displaced to the flexible portion side to the maximum. The contact portion has a shape in which the contour shape viewed from the side where the weight fixing portion is located is circular, and the weight is moved to the flexible portion side by the inner peripheral surface of the support portion and the contact portion. A stopper structure that restricts the range of the displacement amount to be displaced is configured. If the stopper structure is configured by the inner peripheral surface of the support portion and the contact portion of the weight as in the present invention, the substantially circular shape formed on the weight when the weight is largely displaced toward the flexible portion side. These linear contact portions come into contact with the four trapezoidal inclined surfaces of the support portion. Therefore, when acceleration in the vertical direction is applied to the acceleration sensor, the contact portion of the weight comes into contact with the inner peripheral surface of the support portion, so that a large displacement is applied to the flexible portion so as to destroy the flexible portion. Can be prevented. In particular, in the present invention, since the contour shape of the contact portion is linear, the position of the inner peripheral surface where the inner peripheral surface of the support portion contacts the contact portion is a substantially constant position. Therefore, even in mass production, there is an advantage that the variation in performance of each sensor does not increase.

  Also, with such a configuration, the weight can be moved along the four inclined surfaces only by moving the weight closer to the semiconductor sensor main body until the contact portion of the weight comes into contact with the four inclined surfaces. As a result, it is possible to obtain a self-alignment effect in which the center of the weight is coincident with the center line through which the weight passes the center of the weight fixing portion. Therefore, according to the present invention, it is not necessary to align the weight with respect to the support portion of the acceleration sensor body using a special device.

  The contact position between the contact portion and the inclined surface is theoretically arbitrary. However, if the contact position between the contact portion and the inclined surface is positioned closer to the bottom surface side of the support portion than the center position in the thickness direction of the support portion of the inclined surface, the contact portion contacts the boundary portion between the flexible portion and the support portion. The impact force transmitted from the part can be reduced.

  In order to increase the weight of the weight, it is preferable that the weight is made of metal. Even in such a case, if the weight is formed of tungsten having a high specific gravity and inexpensive, it is possible to provide a semiconductor acceleration sensor with a thin sensor and high sensitivity at a low cost.

  In the present invention, a pedestal for supporting the acceleration sensor main body may or may not be provided. In this case, if the weight is shaped so as to be disposed in the two internal spaces straddling the internal space in the support portion and the internal space in the pedestal, the thickness of the entire sensor is increased, but the weight volume is increased. Since the weight of the weight can be increased, the sensitivity can be increased.

  The structure for forming the linear contact portion is arbitrary. For example, an intersection of a first surface extending in a direction along the flexible portion and a second surface extending in a direction intersecting the inner peripheral surface of the support portion with respect to the weight portion located in the internal space of the support portion To form a contact portion. If it does in this way, a linear contact part can be formed with a simple shape.

It is sectional drawing of the semiconductor acceleration sensor of embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is a top view of the acceleration sensor main body of the semiconductor acceleration sensor shown in FIG. It is a reverse view of the acceleration sensor main body of the semiconductor acceleration sensor shown in FIG. (A) And (B) is a figure used in order to demonstrate the method of fixing a weight to an acceleration sensor main body in the semiconductor acceleration sensor shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a semiconductor acceleration sensor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line II-II of FIG. As shown in both drawings, the semiconductor acceleration sensor according to the embodiment of the present invention includes an acceleration sensor body 1, a weight 3 fixed to the acceleration sensor body 1, and a glass base 5 that supports the acceleration sensor body 1. And have.

  3 and 4 are a plan view and a back view of the acceleration sensor main body 1, respectively. As shown in FIGS. 1 to 4, the acceleration sensor main body 1 has a weight fixing portion 7 located at the center, a cylindrical support portion 9 located at the outer peripheral portion, and the weight fixing portion 7 and the support portion 9. A semiconductor crystal substrate made of single crystal silicon is formed by anisotropic etching so as to have a flexible portion 11 having flexibility. A plurality of sensor elements made of diffusion resistance for acceleration detection are formed on the flexible portion 11 on the surface of the acceleration sensor main body 1, and a plurality of electrodes 8 are formed on the support portion 9 ( FIG. 3). In the semiconductor acceleration sensor of this example, the weight 3 is moved by the force based on the acceleration applied from the outside or the force based on the gravitational acceleration applied in a tilted stationary state, and the flexible portion 11 is bent. The resistance value of each of the diffusion resistors is changed to detect biaxial acceleration corresponding to the amount of distortion.

  The weight fixing part 7 has a shape protruding from the flexible part 11 toward the weight 3 in the internal space 10 of the support part 9, and the flexible part 11 passes through the center of the weight fixing part 7. The weight 3 is fixed to the tip so that the center is located on the center line C extending in the direction orthogonal to the extending direction. The weight fixing portion 7 has a polygonal cross section, and its outer peripheral surface is formed as an inclined surface that inclines so as to approach the center line C as it moves away from the side where the flexible portion 11 is located. Yes.

  The support portion 9 has a rectangular annular shape, and the inner peripheral surface has four trapezoidal inclined surfaces 13 of substantially the same shape so as to follow the outer peripheral surface of the truncated pyramidal space. It is configured in combination. The inclined surfaces 13 are inclined so as to approach the center line C toward the side where the flexible portion 11 is located, and constitute a part of a stopper structure described later. In this example, the inclination angle θ with respect to the center line C of the inclined surface 13 is 35.3 °. Due to the structure of the inner peripheral surface of the support portion 9, the internal space 10 of the support portion 9 including the weight fixing portion 7 has a truncated pyramid shape whose transverse cross-sectional shape decreases toward the flexible portion 11. become.

  The weight 3 is formed of tungsten having a profile close to a disk shape. This weight is disposed in two internal spaces straddling the internal space 10 in the support portion 9 and the internal space 12 in the pedestal 5 with one end fixed to the weight fixing portion 7 with an adhesive. The annular portion 3a enters the internal space 10 in the support portion 9. In this example, the annular portion 3a includes a first surface 3b extending in a direction along the flexible portion 11, a second surface 3c extending in a direction intersecting the inner peripheral surface of the support portion 9, and a first surface. The contact portion 3d is formed by an intersection (corner portion) between 3b and the second surface 3c, and the bottom surface 3e is located on the opposite side of the flexible portion 11. 3 d of contact parts are extended in the substantially circular linear shape so that the outline shape seen from the side in which the weight fixing | fixed part 7 is located has a circular shape. Therefore, as shown in FIG. 2, the abutting portion 3 d faces almost the center of each of the four inclined surfaces 13 of the support portion 9. In this example, the contact position between the contact portion 3d and the inclined surfaces 13 is located closer to the bottom surface side of the support portion 9 than the central position in the thickness direction of the support portions 9 of the inclined surfaces 13. Further, a weight stopper structure is constituted by the contact portion 3d and the four inclined surfaces 13 of the support portion 9 described above. Therefore, when the displacement amount of the weight 3 exceeds a predetermined range, the contact portion 3d abuts on the inclined surfaces 13 and the displacement amount of the weight 3 is restricted.

  Next, a method of joining the weight 3 to the acceleration sensor body 1 in the semiconductor acceleration sensor of this example will be described. First, as shown in FIG. 5A, anaerobic adhesive 17 is applied to the weight fixing portion 7 of the acceleration sensor main body 1 to which the base 5 is fixed, and the weight 3 is adsorbed to the vacuum suction device V. The weight 3 is placed on the weight fixing portion 7 after the adhesive 17 is applied. Next, as shown in FIG. 5B, after the suction by the vacuum suction device V is released, the weight 3 is pressed against the acceleration sensor main body 1 using the vacuum suction device V. If it does in this way, the flexible part 11 will bend, the contact part 3d of the weight 3 will contact the inclined surface 13 ... of the support part 9, and the centerline C of the weight 3 and the centerline of an acceleration sensor main body will be referred to. Are matched. In FIG. 5B, the flexible portion 11 is slightly bent although it is difficult to confirm on the drawing. Next, the vacuum suction device V is separated from the weight 3 and returned so that the weight 3 is separated from the support portion 9, and the weight 3 is joined to the acceleration sensor main body 1. If the stopper structure is configured by the contact portion 3d of the weight 3 and the inclined surface 13 of the support portion 9 as in this example, when the weight 3 is largely displaced toward the flexible portion 11, the weight 3 The formed substantially circular linear abutting portion 3d abuts on substantially the center of the four trapezoidal inclined surfaces 13 of the support portion. Therefore, it is possible to prevent a large displacement from being applied to the flexible part 11 to such an extent that the flexible part 11 is destroyed. In particular, since the contour shape of the contact portion 3d is linear, the position of the inner peripheral surface where the inner peripheral surface of the support portion 9 and the contact portion 3d come into contact is a substantially constant position. Therefore, even in mass production, there is an advantage that the variation in performance of each sensor does not increase.

  Further, the weight 3 is displaced along the inclined surfaces 13 only by moving the weight 3 closer to the semiconductor sensor main body 1 until the contact portion 3d of the weight 3 comes into contact with the inclined surfaces 13. In addition, it is possible to obtain a self-alignment effect in which the center of the weight 3 coincides with the center line C of the weight fixing portion 7.

  In this example, the contact portion 3d is formed by the intersection (corner portion) between the first surface 3b and the second surface 3c. However, the present invention is not limited to this. Of course, the contact portion can be formed by a part of the protrusion or curved surface.

  According to the present invention, when vertical acceleration is applied to the acceleration sensor, the contact portion of the weight comes into contact with the inner peripheral surface of the support portion, so that the displacement is large enough to break the flexible portion. It can prevent joining to a bending part. In addition, since the contour shape of the contact portion has a linear shape, the position of the inner peripheral surface where the inner peripheral surface of the support portion contacts the contact portion is a substantially constant position. Therefore, even in mass production, there is an advantage that the variation in performance of each sensor does not increase. Furthermore, the weight is displaced along the four inclined surfaces only by moving the weight closer to the semiconductor sensor body until the contact portion of the weight comes into contact with the four inclined surfaces. As a result, the weight is displaced. A self-alignment effect can be obtained in which the center of the weight coincides with the center line through which the weight passes the center of the weight fixing portion. Therefore, according to the present invention, it is not necessary to align the weight with respect to the support portion of the acceleration sensor body using a special device.

DESCRIPTION OF SYMBOLS 1 Acceleration sensor main body 3 Weight 3d Contact part 5 Base 7 Weight fixed part 9 Support part 11 Flexible part 13 Inclined surface

Claims (5)

The semiconductor crystal substrate is integrally formed by anisotropic etching, has a weight fixing portion at the center, a cylindrical support portion at the outer peripheral portion, and the weight fixing portion and the support portion. A semiconductor sensor main body having a flexible portion having flexibility,
An acceleration sensor element constituted by a diffused resistor formed in the flexible part;
A weight fixed to the weight fixing portion so that the center is positioned on a center line extending in a direction orthogonal to the direction in which the flexible portion extends through the center of the weight fixing portion;
A semiconductor acceleration sensor configured by annularly combining four trapezoidal inclined surfaces of the same shape so that an inner peripheral surface of the support portion follows an outer peripheral surface of a truncated pyramid internal space. ,
The weight has a linear contact portion that contacts the four inclined surfaces constituting the inner peripheral surface when the weight is displaced to the maximum extent toward the flexible portion side,
The contact portion has a shape in which the contour shape seen from the side where the weight fixing portion is located is circular,
A stopper structure that regulates a range of a displacement amount by which the weight is displaced toward the flexible portion side is configured by the inner peripheral surface of the support portion and the contact portion.
The contact position between the contact portion and the inclined surface is located closer to the bottom surface side of the support portion than the central position in the thickness direction of the support portion of the inclined surface ,
A semiconductor acceleration sensor, wherein the contact portion is formed by a part of a curved surface . The semiconductor crystal substrate is integrally formed by anisotropic etching, has a weight fixing portion at the center, a cylindrical support portion at the outer peripheral portion, and the weight fixing portion and the support portion. A semiconductor sensor main body having a flexible portion having flexibility,
An acceleration sensor element constituted by a diffused resistor formed in the flexible part;
A weight fixed to the weight fixing portion so that the center is positioned on a center line extending in a direction orthogonal to the direction in which the flexible portion extends through the center of the weight fixing portion;
The weight fixing part protrudes into the internal space of the cylindrical support part,
The internal space including the weight fixing part has a truncated pyramid shape whose cross-sectional shape decreases toward the flexible part,
The inner peripheral surface of the support portion is composed of four trapezoidal inclined surfaces that follow the outer peripheral surface of the internal space,
A semiconductor acceleration sensor having a shape in which at least a part of the weight is located in the internal space,
The weight is in a linear contact with a portion located in the internal space, which is in contact with the four inclined surfaces constituting the inner peripheral surface when the weight is displaced to the flexible part side to the maximum. Have
The contact portion has a shape in which the contour shape seen from the side where the weight fixing portion is located is circular,
A stopper structure that regulates a range of a displacement amount by which the weight is displaced toward the flexible portion side is configured by the inner peripheral surface of the support portion and the contact portion.
The contact position between the contact portion and the inclined surface is located closer to the bottom surface side of the support portion than the central position in the thickness direction of the support portion of the inclined surface ,
A semiconductor acceleration sensor, wherein the contact portion is formed by a part of a curved surface . It further comprises a cylindrical pedestal on which the support part is placed,
3. The semiconductor acceleration sensor according to claim 1, wherein the weight has a shape that is disposed in two internal spaces across the internal space in the support portion and the internal space in the pedestal. The portion of the weight located in the internal space of the support portion is
The contact portion is formed by an intersection of a first surface extending in a direction along the flexible portion and a second surface extending in a direction intersecting the inner peripheral surface of the support portion. The semiconductor acceleration sensor according to claim 1 or 2.   The semiconductor acceleration sensor according to claim 1, wherein the weight is made of tungsten.

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