JP2009224462A - Capacitance type physical quantity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent a movable electrode portion from being deformed by external stress while suppressing an increase in overall size. <P>SOLUTION: A sensor element 5 comprising the movable electrode portion 6 and fixed electrode portions 7 and 8 is provided by forming a groove in a single-crystal silicon layer 4 provided on a support substrate 2 with an insulating layer 3 interposed. The movable electrode portion 6 has movable electrodes 6d extending in a comb tooth shape from a spindle portion 6a, and also has beam portions 6b at both front and rear ends of the spindle 6a and a first anchor portion 6c on a front end side. An aluminum-made electrode pad 9 is provided on an upper surface of the anchor portion 6c. In the anchor portion 6c, two slits 12 for stress cutting having depth enough for removing the whole single-crystal silicon layer 4 are formed. The slits 12 extend inwardly from both right and left edges of the anchor portion 6c to positions where they cross virtual prolongations obtained by extending both right and left edges of the electrode pad 9. The slid width is not less than 5 μm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a capacitive physical quantity sensor that detects a physical quantity (dynamic quantity) as a change in capacitance, such as an acceleration sensor or a yaw rate sensor.

  As this type of capacitive physical quantity sensor, for example, there is a semiconductor acceleration sensor used in an acceleration sensor device for an automobile airbag. As is well known, this semiconductor acceleration sensor (sensor chip) is based on, for example, a semiconductor substrate (SOI substrate) having a single crystal silicon layer via an oxide film on a support substrate, and micromachining the single crystal silicon layer. By processing, an acceleration detection part (sensor element) composed of a movable electrode part and a pair of fixed electrode parts is formed and obtained.

  The movable electrode portion is positioned at both ends of the weight portion that is long in the direction of the detection axis (for example, the Y axis that is the front-rear direction), the movable electrode that extends from the weight portion in the left-right (X-axis) direction, and the weight portion. It integrally has a beam portion (spring portion) and anchor portions arranged on both end sides or one end side thereof. Among them, the anchor portion is fixedly supported by the support substrate, and the portions other than the anchor portion are floated on the support substrate. A square electrode pad made of aluminum, for example, is provided on the upper surface of the anchor portion. The fixed electrode portion is configured to have a comb-shaped fixed electrode arranged with a gap in the front-rear direction with respect to the comb-shaped movable electrode.

  Thus, capacitors are formed between the movable electrode portion (movable electrode) and the fixed electrode portion (fixed electrode), and the capacitance of these capacitors is determined by the displacement of the movable electrode portion due to the acceleration in the Y-axis direction. Therefore, the acceleration can be taken out as a change in the capacitance value. The semiconductor acceleration sensor (sensor chip) is mounted on, for example, a circuit chip having a signal processing circuit by adhesion, and the circuit chip is accommodated in the ceramic package by adhesion. At this time, the electrical connection between the semiconductor acceleration sensor and the circuit chip and the electrical connection between the circuit chip and the package side are respectively made by bonding wires.

  By the way, in this type of semiconductor acceleration sensor, as described in, for example, Patent Document 1 and Patent Document 2, stress from the outside acts on the sensor element portion due to, for example, temperature change, warping, etc. There are circumstances that cause deformation. In particular, due to the difference in coefficient of thermal expansion between the electrode pad made of aluminum and the substrate made of silicon, the movable electrode portion is deformed in the detection axis direction, and as a result, the movable electrode is fixed between the movable electrode and the fixed electrode. There is a problem in that the gap changes, the sensor output fluctuates, and the detection accuracy decreases.

Therefore, in order to solve such a problem, in Patent Document 1, the sensor element is arranged at the center of the chip, and the pattern of the sensor element (movable electrode portion and left and right fixed electrode portions) extends in the Y-axis direction. A device is devised such that it is arranged in line symmetry (left-right symmetry) with respect to the central axis. Patent Document 2 discloses a configuration in which three dummy electrode pads are added so as to be point-symmetric with respect to the center of the sensor element with respect to the electrode pad of the movable electrode portion and the electrode pads of the left and right fixed electrode portions. Has been.
JP 2002-303636 A JP 2003-14777 A

  However, in the configuration in which the deformation of the movable electrode portion due to external stress as described in Patent Document 1 and Patent Document 2 is intended to be suppressed by imparting symmetry to the pattern of the sensor element and the electrode pad, There is a problem that the size of the area is increased, or the degree of freedom in design related to the pattern of the sensor element and the arrangement of the electrode pads is lowered.

  The present invention has been made in view of the above circumstances, and a purpose thereof is a capacitive physical quantity sensor capable of effectively preventing deformation of the movable electrode portion due to external stress while suppressing increase in size of the whole. Is to provide.

  In order to achieve the above object, a capacitive physical quantity sensor according to claim 1 of the present invention is configured by providing a sensor element having a movable electrode portion and a fixed electrode portion on a support substrate, The movable electrode part is integrally provided with an anchor part fixedly supported on a support substrate and provided with an electrode pad on the upper surface, and a movable electrode supported by the anchor part via a beam part and displaced according to the action of a physical quantity. And a stress blocking slit is formed in the anchor portion between the beam portion and the electrode pad.

  According to this, since the stress blocking slit is provided at a position between the beam portion of the anchor portion and the electrode pad, the stress in the anchor portion is buffered by the slit portion, and the movable electrode portion Can be suppressed. As a result, it is possible to prevent the movable electrode portion from being deformed due to external stress. Also, in this case, it is not necessary to add a dummy electrode pad or to give symmetry to the sensor element pattern, so that the overall size can be suppressed and the degree of freedom in design is reduced. You can do without.

  More specifically, two slits are formed from both side edges of the anchor portion toward the inside, and the slits are virtual extension lines in which both edge portions of the electrode pad extend to the beam portion side. Can be formed so as to extend to positions crossing each of them (the invention of claim 2). Thereby, the stress generated due to the difference in thermal expansion coefficient between the electrode pad and the anchor portion can be absorbed by the slit, which is effective.

  In other words, the virtual extension line is a line obtained by extending the side along the movable direction of the vibrator among the sides of the rectangular electrode pad. In addition, the slits are formed so as to extend to the positions crossing the virtual extension lines, in other words, in the remaining portion (connection portion) of the anchor portion where the slit is provided, in the direction perpendicular to the movable direction of the vibrator. This means that the width dimension (dimension b in FIG. 2) is smaller than the width dimension in the direction orthogonal to the movable direction of the vibrator in the electrode pad.

  Further, at this time, each slit is preferably formed to extend inward by a length of 5% or more with respect to the width dimension between both side edges of the electrode pad from the virtual extension line (Invention of claim 3), It is excellent due to the deformation preventing effect of the movable electrode portion. Furthermore, in the present invention, it is desirable to form the slit so that the slit width dimension is 5 μm or more (the invention of claim 4). Thereby, it becomes more excellent in the effect of the stress absorption from an anchor part. The upper limit of the slit width is not particularly limited, but may be appropriately designed depending on the size (area) of the anchor portion and the wiring resistance, and can be determined within a range of 80 μm or less, for example.

  The capacitive physical quantity sensor according to claim 5 of the present invention is configured by providing a sensor element having a movable electrode portion and a fixed electrode portion on a support substrate, and the movable electrode portion is provided on the support substrate. An anchor portion that is fixedly supported and provided with an electrode pad on the upper surface, and a movable electrode that is supported by the anchor portion via a beam portion and is displaced according to the action of a physical quantity are integrally provided. Is characterized in that the separation distance between the beam portion and the electrode pad is 100 μm or more.

  According to this, by taking a long separation distance between the beam portion of the anchor portion and the electrode pad, it is possible to suppress the stress from reaching the movable electrode portion by exhibiting a buffering action of the stress in the anchor portion. According to the inventor's research, it has been clarified that the effect of stress relaxation is excellent by setting the separation distance to 100 μm or more. As a result, it is possible to prevent the movable electrode portion from being deformed due to external stress. In this case as well, there is no need to add dummy electrode pads or provide symmetry to the sensor element pattern, so the overall size can be suppressed and the degree of design freedom is reduced. You can do without. Note that the upper limit of the separation distance between the beam portion and the electrode pad can also be determined as appropriate in consideration of the overall size (area) of the chip and the wiring resistance. For example, it can be determined within a range of 270 μm or less. it can.

  Hereinafter, several embodiments embodying the present invention will be described with reference to the drawings. In each of the embodiments described below, the present invention is applied to a capacitive acceleration sensor device for, for example, an automobile airbag system (collision detection).

(1) First Embodiment First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 schematically shows the entire configuration of a semiconductor acceleration sensor chip 1 as a capacitive physical quantity sensor according to the present embodiment.

  Although illustration and detailed description are omitted, the semiconductor acceleration sensor chip 1 is bonded to, for example, a circuit chip having a signal processing circuit via an adhesive sheet, and the circuit chip is bonded to a ceramic package with an adhesive. So that an acceleration sensor device can be obtained. At this time, the electrical connection between the semiconductor acceleration sensor chip 1 (electrode pad to be described later) and the circuit chip, and the electrical connection between the circuit chip and the package side are made by bonding wires.

  As shown in FIGS. 1B and 2B, the semiconductor acceleration sensor chip 1 according to the present embodiment is, for example, a single crystal on a support substrate 2 made of silicon via an insulating layer (oxide film) 3. A rectangular (square) SOI substrate on which the silicon layer 4 is formed is used as a base, and a groove is formed in the single-crystal silicon layer 4 on the surface by a micromachining technique, so that it is located in a central rectangular region. Thus, a sensor element (mechanical quantity (acceleration) detection unit) 5 is provided. In this case, the sensor element 5 detects acceleration in the front-rear direction (Y-axis direction) in FIG. 1A and has a detection axis (Y-axis) in one direction. The thickness of the single crystal silicon layer 4 is set to 22 μm, for example.

  As shown in FIG. 1A, the sensor element 5 includes a movable electrode portion 6 that is displaced in the Y-axis direction according to the action of acceleration, and a pair of left and right fixed electrode portions 7 and 8. The Among them, the movable electrode portion 6 has beam portions 6b each having a rectangular frame shape elongated in the left-right direction at both front and rear ends of the weight portion 6a extending in the front-rear direction at the center of the sensor element 5, and the beam portion 6b on the front side in the drawing. The first anchor portion 6c is further provided on the front end side, and the second anchor portion 6e is further provided on the rear end side of the rear beam portion 6b. Each of the movable electrodes 6d has a plurality of narrow widths extending in a comb-like shape from the weight portion 6a in the left-right direction.

  A rectangular electrode pad 9 made of, for example, aluminum is provided on the upper surface of the first anchor portion 6c. At this time, the movable electrode portion 6 has the lower insulating film 3 removed except for the anchor portions 6c and 6e, and only the anchor portions 6c and 6e are supported by the support substrate 2, that is, the remaining portions. The part is supposed to float in the air. Although a large number of the movable electrodes 6d are actually provided, most of the movable electrodes 6d are omitted for the sake of convenience in FIG. The electrode pad 9 is formed with a thickness dimension of 1.3 μm, for example.

  On the other hand, the left fixed electrode portion 7 is fixed in a number of narrow widths extending in a comb-like shape to the right from a vertically long rectangular base portion 7a that extends in the front-rear direction on the left side portion in FIG. It has an electrode 7b (only two are shown). These fixed electrodes 7b are provided on the immediate rear side of the movable electrode 6d so as to be adjacent to each other through a minute gap. The base portion 7a is provided extending forward (front side in the figure), and an aluminum electrode pad 10 is also provided on the upper surface of the front end portion so as to be arranged to the left of the electrode pad 9.

  The right fixed electrode portion 8 includes a plurality of narrow fixed electrodes 8b (2 extending in a comb-like shape to the left from a vertically long rectangular base portion 8a that extends in the front-rear direction in FIG. Only the book is shown). These fixed electrodes 8b are provided so as to be adjacent to each other in parallel with a minute gap immediately in front of the movable electrode 6d. The base portion 8a is provided to extend forward (front side in the figure), and an aluminum electrode pad 11 is also provided on the upper surface of the front end portion so as to be arranged to the right of the electrode pad 9. In these fixed electrode portions 7 and 8, the insulating film 3 on the lower surface side of the portions excluding the base portions 7a and 8a, that is, the portions of the fixed electrodes 7b and 8b is removed.

  Thus, between the movable electrode portion 6 (movable electrode 6d) and the fixed electrode portion 7 (fixed electrode 7b), and between the movable electrode portion 6 (movable electrode 6d) and the fixed electrode portion 8 (fixed electrode 8b). Capacitors of these capacitors are respectively formed, and the capacitances of these capacitors change differentially according to the displacement of the movable electrode portion 6 (movable electrode 6d) due to the action of acceleration in the Y-axis direction. Therefore, the acceleration can be taken out as a change in the capacitance value.

  In the present embodiment, as shown in FIGS. 1 and 2, the first anchor portion 6c of the movable electrode portion 6 is located between the beam portion 6b and the electrode pad 9 so as to interrupt stress. Two slits 12 are formed. As shown in FIG. 2B, these slits 12 are formed at a depth that allows the entire single crystal silicon layer 4 to be removed. Depending on the manufacturing method, the insulating layer 3 may be formed to a depth that can be removed to the lower insulating layer 3.

  These two slits 12 extend inward from the left and right side edges of the first anchor portion 6c, and each slit 12 extends from the left and right end edges of the electrode pad 9 to the beam portion 6b side (Y It extends to a position that crosses the virtual extension line L extending in the axial direction. These slits 12 are formed to extend inward by a length of 5% or more with respect to the width dimension between both side edges of the electrode pad 9 from the virtual extension line L. Furthermore, these slits 12 are formed so that the slit width dimension c is 5 μm or more.

  Specifically, the left and right width dimension a of the first anchor portion 6c is 180 μm, the length dimension e of the front and rear (up to the beam portion 6b) is 253 μm, and the vertical and horizontal dimensions (dimension f) of the electrode pad 9 are 120 μm × 120 μm. The horizontal length d of the slit 12 is 40 μm, the width b of the connecting portion of the first anchor portion 6 c (the portion excluding the slit 12) is 100 μm, the width c of the slit 12 is 30 μm, and the electrode pad 9 The length dimension g from the end portion to the beam portion 6b is 113 μm, and the length dimension h from the end portion of the electrode pad 9 to the slit 12 is 20 μm.

  In the semiconductor acceleration sensor chip 1 of the present embodiment configured as described above, during use, for example, due to a change in temperature, external stress acts on the sensor element 5 portion, and deformation such as warping may occur. Conceivable. In particular, due to the difference in coefficient of thermal expansion between the electrode pad 9 made of aluminum and the first anchor portion 6c, the movable electrode portion 6 is deformed in the detection axis (Y-axis) direction. The gap between the movable electrode 6d and the fixed electrodes 7b and 8b changes, and the sensor output may fluctuate, leading to a decrease in detection accuracy.

  However, in this embodiment, the stress blocking slit 12 is provided at a position between the beam portion 6b of the first anchor portion 6c and the electrode pad 9, so that the stress in the first anchor portion 6c is reduced. Is buffered by the slit 12 portion and can be prevented from reaching the weight portion 6a and the movable electrode 6d portion. As a result, the deformation of the movable electrode portion 6 due to the external stress can be prevented, and the decrease in detection accuracy can be prevented.

  Here, in order to confirm the effect of the slit 12 in the present embodiment, the present inventor has 10 samples S1 each of two types of semiconductor acceleration sensor chips, one having a slit formed in an anchor portion and one having no slit. With respect to S2, an actual temperature increase test was performed to determine the relationship between temperature and output. 3 and 4 show the shape (a) of the sensor chip as samples S1 and S2 and the test result (b) thereof.

  As shown in FIGS. 3A and 4A, samples S1 and S2 formed sensor elements E1 and E2 at positions shifted from the center to the near side of a relatively large SOI substrate. The electrode pad is provided only on one side (asymmetrically). In the sample S1 in FIG. 3A, the two slits as described above are formed in the anchor portion, and in the sample S2 in FIG. 4A, there is no slit in the anchor portion.

  In the test, the samples S1 and S2 are assembled as an acceleration sensor device, the temperature is increased from room temperature (25 ° C.) to 125 ° C., and the fluctuation of the output voltage of the sensor in the stationary state, that is, the state where acceleration is not acting (0G). This was done by examining. At this time, the output fluctuation at 125 ° C. was compared while correcting the output from 25 ° C. to 85 ° C. to be flat. The results are shown in FIGS. 3 (b) and 4 (b). As shown in FIG. 3B, in the sample S1 in which the slit is formed in the anchor portion, even when the temperature is raised to 125 ° C., the fluctuation of the output is small and the fluctuation is small. On the other hand, in the sample S2 in which no slit is present in the anchor portion in FIG. 4B, the output fluctuates greatly as the temperature rises, and the variation is large.

  From this test result, when the stress blocking slit 12 is formed in the first anchor portion 6c, deformation of the movable electrode portion 6 due to thermal stress (temperature change) can be prevented, and good detection accuracy is ensured. I can understand that you can. Further, it has been clarified that by providing the slits 12, the electrode pads 9 do not have to be arranged symmetrically even if the formation position of the sensor element 5 is shifted from the center of the chip.

  Next, the inventor conducted a simulation test to confirm whether or not the width dimension c of the slit 12 formed in the first anchor portion 6c affects the effect of stress absorption. This test was performed by obtaining the deformation amount when the slit 12 was formed with several different width dimensions c with respect to the movable electrode portion 6 having a shape (dimension) as shown in FIG. The result is shown in FIG. In FIG. 5A, the movable electrode 6d is not shown.

  In this case, as the entire shape of the movable electrode portion 6, the second anchor portion 6e on the rear end side also has a length (dimension e is 253 μm) equivalent to that of the first anchor portion 6c on the front end side. Is provided. The dimensions of each part such as the size of the first anchor part 6c are as described above, but the width dimension b of the connecting part (the part excluding the slit 12) of the first anchor part 6c is 50 μm (slit 12 horizontal lengths d are each 65 μm). The width c of the slit 12 is changed to 0 (no slit), 5 μm, 10 μm, 20 μm, 30 μm, 50 μm, 70 μm, and 80 μm.

  From this result, it was clarified that by forming the slit 12 so that the width dimension c is 5 μm or more, the amount of deformation can be negligibly reduced and the stress absorption effect is excellent. is there. The upper limit of the slit width c is not particularly limited, but may be appropriately designed depending on the size (area) of the first anchor portion 6c and the wiring resistance, and can be set to 80 μm or less, for example.

  Furthermore, although detailed explanation is omitted, according to the research (simulation) of the present inventor, two slits 12 are formed inwardly from both side edges of the first anchor portion 6c, and the slits 12 are formed. If the electrode pads 9 are formed so as to extend across the virtual extension lines L extending from both ends of the electrode pad 9 to the beam portion side, the stress absorption effect is excellent. At this time, each slit 12 has a length of 5% or more with respect to the width dimension f between both side edges of the electrode pad 9 with respect to the virtual extension line L (120 × 0.05 = 6 μm in this embodiment). As described above, it is desirable to extend inwardly, and it has become clear that the movable electrode portion 6 is more excellent in preventing deformation.

  As described above, according to the present embodiment, since the stress blocking slit 12 is formed in the first anchor portion 6c of the movable electrode portion 6 between the beam portion 6b and the electrode pad 9, There is an excellent effect that the deformation of the movable electrode portion 6 due to the stress can be effectively prevented. In addition, since a configuration in which a dummy electrode pad is added or a configuration in which symmetry is provided to the pattern of the sensor element 5 or a configuration in which the sensor element 5 is provided at the center of the chip is unnecessary, the overall size can be suppressed. In addition, the design freedom can be eliminated.

(2) Second to Fourth Embodiments FIGS. 6, 7 and 8 show the second, third and fourth embodiments of the present invention, respectively. The second to fourth embodiments are different from the first embodiment in the shape of a slit formed in the first anchor portion 6c of the movable electrode portion 6. Accordingly, the same parts as those in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted, and only differences will be described below.

  FIG. 6 shows a second embodiment of the present invention. In the second embodiment, the first anchor portion 6c is positioned between the beam portion 6b and the electrode pad 9 in the left-right direction. The two slits 21 formed so as to extend are not opened at the side edge portion of the anchor portion 6a, but are provided in a state where a cut is made inside the anchor portion 6c (closed state). . That is, the front and rear portions of the first anchor portion 6a are connected to each other at both side edges and the central portion with the two slits 21 interposed therebetween. Also in this case, the two slits 21 are formed at positions that respectively cross the virtual extension lines L that extend from the left and right edge portions of the electrode pad 9 to the beam portion 6b side (Y-axis direction). .

FIG. 7 shows a third embodiment of the present invention. In this third embodiment, the two slits 22 formed in the first anchor portion 6c are provided in a triangular shape. Yes.
FIG. 8 shows a fourth embodiment of the present invention. In this fourth embodiment, the two slits 23 formed in the first anchor portion 6c are formed into an elliptical (oval) shape. Yes.

  Also in the second to fourth embodiments, the stress blocking slits 21, 22, 23 are located in the first anchor portion 6 c of the movable electrode portion 6 between the beam portion 6 b and the electrode pad 9. As in the first embodiment, it is possible to effectively prevent deformation of the movable electrode portion 6 due to external stress while suppressing the increase in size as a whole. be able to.

(3) Fifth Example and Other Examples Next, a fifth example of the present invention will be described with reference to FIGS. FIG. 9 schematically shows a semiconductor acceleration sensor chip 31 as a capacitive physical quantity sensor according to this embodiment, and the following description will focus on differences from the semiconductor acceleration sensor chip 1 of the first embodiment. . The semiconductor acceleration sensor chip 31 is configured by providing a sensor element 5 having a movable electrode portion 32 and a pair of left and right fixed electrode portions 7 and 8 on the support substrate 2.

  The movable electrode portion 32 has beam portions 32b at both front and rear end portions of the weight portion 32a extending in the front-rear direction, and further has a first anchor portion 32c on the front end side of the beam portion 32b on the near side in the drawing. A second anchor portion 32e is further provided on the rear end side of the side beam portion 32b. Each of the movable electrodes 32d has a plurality of narrow widths extending from the weight portion 32a in the left-right direction in a comb-like shape. A rectangular electrode pad 9 made of, for example, aluminum is provided on the upper surface portion of the first anchor portion 32c.

  At this time, in the first anchor portion 32c, the entire anchor portion 32b is formed relatively long in the front-rear direction instead of providing the slits as in the first to fourth embodiments. By arranging the electrode pad 9 on the front end side, the length dimension (separation distance) g from the end portion of the electrode pad 9 to the beam portion 32b is set to 100 μm or more. In this embodiment, the separation distance g is, for example, 130 μm.

  According to the configuration of the present embodiment, in the first anchor portion 32c, the distance g between the beam portion 32b and the electrode pad 9 is relatively long, so that the stress in the first anchor portion 32c is relieved. Thus, it is possible to prevent the movable electrode portion 32 from being reached. According to the inventor's research, it has been clarified that the effect of stress relaxation is excellent by setting the separation distance g to 100 μm or more.

  FIG. 10 shows a simulation of the relationship between the separation distance g and the amount of deformation of the movable electrode portion when the inventor changes the separation distance g between the beam portion and the electrode pad in the first anchor portion. The test results are shown. In FIG. 10, the curve A shows the case where no slit is provided, but here, the case where the slit as in the first embodiment is formed is also simulated and shown by the curve B. .

  From this result, when the separation distance g between the beam part and the electrode pad is about 100 μm or more, the deformation of the movable electrode part hardly occurs, and more preferably, the deformation amount is set to 130 μm or more. Was almost zero. Further, when the slit was formed (curve B), the movable electrode portion could be similarly prevented from being deformed by setting the separation distance g between the beam portion and the electrode pad to 50 μm or more. Note that the upper limit of the separation distance g between the beam portion and the electrode pad can also be determined as appropriate in consideration of the overall size (area) of the chip and the wiring resistance, for example, within a range of 270 μm or less. Can do.

  Accordingly, also in this embodiment, the first anchor portion 32c of the movable electrode portion 32 is configured such that the separation distance g between the beam portion 32b and the electrode pad 9 is relatively large (100 μm or more). There is an excellent effect that the deformation of the movable electrode portion 32 due to the above can be effectively prevented. In addition, since a configuration in which a dummy electrode pad is added or a configuration in which symmetry is provided to the pattern of the sensor element 5 or a configuration in which the sensor element 5 is provided at the center of the chip is unnecessary, the overall size can be suppressed. Moreover, it is possible to do without reducing the degree of freedom of design.

  In each of the above embodiments, the present invention is applied to the acceleration sensor device. However, the present invention can also be applied to other capacitive physical quantity sensors having a detection axis in one direction such as a yaw rate sensor. In addition, the present invention is not limited to the embodiments described above and shown in the drawings. For example, various modifications can be made to the shape and material of the sensor element, the dimensions and arrangement of each part such as the anchor part and the electrode pad, and the like. It can be implemented with appropriate modifications within the scope not departing from the gist.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view of a sensor chip according to a first embodiment of the present invention (a) and a longitudinal side view along a center line (Y axis) (b). An enlarged plan view showing the anchor portion (a) and an enlarged vertical side view along the line II-II (b) The figure which shows the sample shape (a) and test result (b) of a temperature rising test of the sensor chip which formed the slit in the anchor part The figure which shows the sample shape (a) of a sensor chip which does not have a slit in an anchor part, and the test result (b) of a temperature rising test The figure which shows the test result which investigated the relationship between the width dimension of a slit, and the deformation of a movable electrode part FIG. 2 (a) equivalent view showing the second embodiment of the present invention. FIG. 2A equivalent view showing a third embodiment of the present invention. FIG. 2A equivalent view showing the fourth embodiment of the present invention. FIG. 9 shows a fifth embodiment of the present invention and is equivalent to FIG. The figure which shows the test result which investigated the relationship between the separation distance from the edge part of an electrode pad to a beam part, and the deformation amount of a movable electrode part

Explanation of symbols

  In the drawings, 1 and 31 are semiconductor acceleration sensor chips (capacitive physical quantity sensors), 2 is a support substrate, 5 is a sensor element, 6 and 32 are movable electrode portions, 6a and 32a are weight portions, 6b and 32b are beam portions, 6c and 32c are first anchor portions, 6d and 32d are movable electrodes, 7 and 8 are fixed electrode portions, 7b and 8b are fixed electrodes, 9 is an electrode pad, 12, 21, 22, and 23 are slits, and L is a virtual one. An extension line is shown.

Claims (5)

A capacitive physical quantity sensor configured by providing a sensor element having a movable electrode portion and a fixed electrode portion on a support substrate,
The movable electrode unit integrally includes an anchor unit fixedly supported on the support substrate and provided with an electrode pad on the upper surface, and a movable electrode supported by the anchor unit via a beam unit and displaced according to the action of a physical quantity. In addition to being configured,
The capacitive physical quantity sensor, wherein a stress blocking slit is formed in the anchor portion between the beam portion and the electrode pad.   Two slits are formed inwardly from both side edges of the anchor portion, and each of the slits extends to a position crossing a virtual extension line extending from both ends of the electrode pad to the beam side. The capacitive physical quantity sensor according to claim 1, wherein:   3. The capacitor according to claim 2, wherein the slit is formed to extend inward by a length of 5% or more with respect to a width dimension between both side edges of the electrode pad from the virtual extension line. Formula physical quantity sensor.   The capacitive physical quantity sensor according to any one of claims 1 to 3, wherein the slit is formed so that a slit width dimension thereof is 5 µm or more. A capacitive physical quantity sensor configured by providing a sensor element having a movable electrode portion and a fixed electrode portion on a support substrate,
The movable electrode unit integrally includes an anchor unit fixedly supported on the support substrate and provided with an electrode pad on the upper surface, and a movable electrode supported by the anchor unit via a beam unit and displaced according to the action of a physical quantity. In addition to being configured,
The capacitive physical quantity sensor is characterized in that the anchor portion is provided such that a separation distance between the beam portion and the electrode pad is 100 μm or more.

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