JP2010256234A - Acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acceleration sensor having high reliability. <P>SOLUTION: The acceleration sensor includes a fixed part, a weight part being displaceable in relation to the fixed part, a beam part of which the first end is connected to the fixed part and the second end to the weight part, a resistance element which is disposed in the beam part and the resistance value of which varies according to bending of the beam part, and a conductor layer which is provided for connecting the resistance value of the resistance element to an external circuit and which has a connection part connected electrically to the resistance element and disposed at a position where a stress impressed thereon due to the displacement of the weight part is smaller than that on the resistance element and has a wiring part which extends from the connection part and is disposed on a surface expanding to a thickness position different from that of the resistance element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an acceleration sensor.

  An acceleration sensor that detects acceleration using the piezoresistance effect is known (for example, Patent Document 1). The acceleration sensor of Patent Document 1 includes a weight portion, a beam portion that supports the weight portion, a fixed portion that supports the beam portion, a piezoresistive element provided in the beam portion, and a metal wiring connected to the piezoresistive element. And have. An insulating layer is formed on the beam portion so that a part of the piezoresistive element is exposed, and the metal wiring is directly connected to the piezoresistive element at the exposed portion and is routed on the insulating layer. Yes.

  Here, when an external force proportional to the acceleration is applied to the acceleration sensor, the weight portion is displaced with respect to the fixed portion and the beam portion is bent and deformed. Then, the acceleration is detected by detecting a change in the resistance value of the piezoresistive element in which the bending deformation occurs together with the beam portion.

JP-A-11-160348

  However, when a strong impact is applied to the acceleration sensor described in Patent Document 1, there is a problem that the beam breaks at a portion where the metal wiring and the resistance element are connected.

  The present invention has been devised in view of the above problems, and an object of the present invention is to provide a highly reliable acceleration sensor that does not break a beam even when a strong impact is applied. .

The acceleration sensor of the present invention includes a fixed portion, a weight portion that is displaceable with respect to the fixed portion, a beam portion having a first end connected to the fixed portion, and a second end connected to the weight portion, and the beam A resistance element whose resistance value is changed according to the bending of the beam part, and a conductor layer for connecting the resistance element to an external circuit, electrically connected to the resistance element, A conductor having a connection portion disposed at a position where stress applied by displacement of the weight portion is smaller than that of the resistance element, and a wiring portion disposed on a surface extending from the connection portion and extending in a thickness position different from that of the resistance element. And a layer.

  According to the acceleration sensor of the present invention, in the conductor layer for connecting to the external circuit, the connection part electrically connected to the resistance element is arranged at a position where the stress applied by the displacement of the weight part is smaller than that of the resistance element. Therefore, even when a strong impact is applied, the beam portion can be prevented from breaking. Thereby, a highly reliable acceleration sensor can be provided.

(A), (b), (c) is the typical top view, sectional view, and principal part enlarged view showing a 1st embodiment of the present invention, respectively. It is sectional drawing which shows the modification of the acceleration sensor shown in FIG. It is a typical principal part enlarged plan view which shows 2nd Embodiment of this invention. (A), (b) is a typical principal part enlarged plan view which shows 3rd Embodiment of this invention, respectively, and a typical principal part expanded sectional view which shows the modification. It is a perspective view which shows the modification of the acceleration sensor shown in FIG.

  Exemplary embodiments of an acceleration sensor according to the present invention will be described below in detail with reference to the drawings. Further, the drawings used in the following embodiments are schematic, and the dimensional ratios on the drawings do not necessarily match the actual ones. In order to facilitate understanding, illustration of some components located on the upper surface may be omitted. Further, the present invention is not limited to the following embodiments, and various changes and improvements can be made without departing from the gist of the present invention. In this embodiment, a three-dimensional acceleration sensor element using the piezoresistance effect will be described as an example.

(First embodiment)
1A, 1B, and 1C are a plan view of an acceleration sensor 10 (hereinafter, simply referred to as the sensor 10) according to an embodiment of the present invention, and II in FIG. It is sectional drawing in a line, and the enlarged view of the area | region enclosed with the broken line of FIG.1 (b).

  As shown in FIG. 1, the sensor 10 includes a weight part 11, a frame-like fixing part 13 surrounding the weight part 11, one end (first end) connected to the fixing part 13, and the other end (second end). ) Is connected to the weight portion 11, the beam portion 12, the pad electrode 14 formed on the fixed portion 13, the resistance element 15 formed on the beam portion 12, and the conductor layer 16 that connects the resistance element 15 to an external circuit. And have.

  When acceleration is applied to the sensor element 10, a force corresponding to the acceleration acts on the weight portion 11, and the weight portion 11 is displaced (moved) with respect to the fixed portion 13 so that the beam portion 12 is bent. Yes. Due to this bending, stress is applied to the resistance element 15, and a resistance value that changes according to the stress is taken out to the external circuit via the conductor layer 16 and the pad electrode 14 and detected.

  Here, the conductor layer 16 is electrically connected to the resistance element 15, and a surface (XY plane) extending from the connection part 16 a and extending to a different thickness position (Z-axis direction in the drawing) from the resistance element 15. And a wiring portion 16b disposed on the board. The wiring part 16 b is disposed on the insulating layer 17 that covers the weight part 11, the beam part 12, and the fixing part 13 excluding the part connected to the connection part 16 a of the resistance element 15. Thereby, the wiring part 16b can be freely routed in a state where electrical insulation from the resistance element 15 is ensured except for the necessary part. The connection portion 16 a is disposed at a position where the stress applied by the displacement of the weight portion 11 is smaller than that of the resistance element 15. In the sensor 10 shown in FIG. 1, in order to reduce the stress applied to the connection portion 16 a rather than the resistance element 15, the connection portion 16 a and the connection portion 16 a It is electrically connected by contact.

  By adopting such a configuration, it is possible to provide a highly reliable sensor 10 in which breakage (breakage) of the beam portion 12 is suppressed as compared with a conventional acceleration sensor. This is presumably due to the following mechanism. That is, since the resistance element is usually disposed at a position where stress is concentrated in the beam portion in order to increase the detection sensitivity, the stress is also concentrated at a portion where the conductor layer 16 and the resistance element 15 are connected. In the conventional acceleration sensor, a step is formed by the insulating layer and the conductor layer at a portion where the stress is concentrated. Therefore, the stress is further concentrated by the step and the beam portion may be damaged.

  On the other hand, the sensor 10 arranges the connection portion 16a in the weight portion 11 or the fixed portion 13 so that the stress applied to the connection portion 16a is smaller than that of the resistance element 15, thereby causing stress due to the displacement of the weight portion 11. The concentration location and the stress concentration location due to the step shape can be shifted. Thereby, even if the weight part 11 is displaced, the connection part 16a will be arrange | positioned in the position where stress distribution will not change with the periphery, and can suppress the failure | damage of the beam part 12. FIG. Here, the stress applied to the resistance element 15 is the maximum value in the region where the resistance element 15 is disposed.

  In addition, the stress concentration location in the beam portion 12 is near the first end and the second end connected to the fixed portion 13 and the weight portion 11. For this reason, the connection portion 16 a does not have to be disposed on the fixed portion 13 and the weight portion 11 for the portion where the resistance element 15 and the conductive layer 16 are connected in the vicinity of the center of the beam portion 12.

  Next, the configuration of the sensor 10 as described above will be described in detail.

The weight part 11, the fixing part 13, and the beam part 12 can be integrally formed by processing, for example, an SOI (Silicon on Insulator) substrate. In such an SOI substrate, a semiconductor layer made of n-type or p-type Si is formed on one main surface side of an insulating layer made of SiO ₂ , and a support layer made of Si is formed on the other main surface side. What is necessary is just to use. The weight portion 11 and the fixing portion 13 are configured by the semiconductor layer, the insulating layer, and the support layer, and the beam portion may be processed so as to be configured by the semiconductor layer.

  The weight portion 11 is preferably made as large as possible in order to increase sensitivity to acceleration, but the shape and size thereof may be set as appropriate. In this example, the planar shape is substantially square, and the length of one side is set to, for example, 0.25 mm to 0.5 mm. Moreover, the thickness of the weight part 11 is set to 0.2 mm-0.625 mm, for example. Although there is no particular limitation, it is preferable that the thickness is the same as the thickness of the fixing portion 13 described later.

  A frame-shaped fixing portion 13 is formed so as to surround the weight portion 11. The fixed portion 13 has a substantially square opening and has a substantially square opening slightly larger than the weight portion 11 at the center. The fixed portion 13 has one side set to, for example, 0.8 mm to 3.0 mm, and the width of the arm (side) (the width in the direction perpendicular to the longitudinal direction of the arm; w in FIG. 1) is, for example, 0.1 mm to 1 .8mm is set. Moreover, the thickness (t of FIG. 1) of the fixing | fixed part 13 is set to 0.2 mm-0.625 mm, for example.

  A beam portion 12 is provided between the fixed portion 13 and the weight portion 11 as shown in FIG. The beam portion 12 has one end connected to the central portion on the upper surface side of each side of the weight portion 11, and the other end connected to the central portion on the upper surface side (one main surface 13 a side) of each side in the inner periphery of the fixed portion 13. In the sensor element 10 according to the present embodiment, four beam portions 12 are provided.

  The beam portion 12 has flexibility. When acceleration is applied to the sensor 10, the weight portion 11 moves, and the beam portion 12 bends as the weight portion 11 moves. For example, the beam portion 12 has a length in the longitudinal direction set to 0.1 mm to 0.8 mm, a width (a length in a direction perpendicular to the longitudinal direction) set to 0.01 mm to 0.2 mm, and a thickness of 5 μm. It is set to ˜20 μm. Thus, flexibility is expressed by forming the beam portion 12 to be elongated and thin.

  A plurality of resistance elements 15 are formed on the upper surface of the beam portion 12. More specifically, when the beam portion 12 is made of n-type Si, the resistance element 15 can be configured by a piezoresistance element formed by implanting or diffusing boron. In the present embodiment, these resistances are placed at predetermined positions on the beam portion 12 so that acceleration in the three-axis directions (X-axis direction, Y-axis direction, and Z-axis direction in the three-dimensional orthogonal coordinate system shown in FIG. 1) can be detected. An element 15 is formed.

  For example, two resistance elements 15 for detecting acceleration in the X-axis direction are provided on the two beam parts 12 extending in the X-axis direction, and two resistance elements 15 are arranged on each beam part 12. . Among these four resistance elements 15, the resistance elements arranged on the fixing portion 13 side are connected in series by a bonding wire (not shown) connected to the conductor layer 16 and the pad electrode 14, and are connected to the fixing portion 11 side. The arranged resistance elements 15 are connected in series and connected in parallel to form a bridge circuit. The two beam portions 12 extending in the Y-axis direction are provided with four resistance elements 15 for detecting acceleration in the Y-axis direction. These resistance elements 15 are used for detecting acceleration in the X-axis direction. The resistor elements 15 are arranged in the same manner, and the resistor elements are connected by the conductor layer 16 to constitute a bridge circuit.

  In addition, four resistance elements 15 for detecting acceleration in the Z-axis direction are respectively connected to four resistance elements 15 for detecting acceleration in the X-axis direction on two beam portions 12 extending in the X-axis direction. It is formed to line up. The resistance element 15 for acceleration detection in the Z-axis direction is different from the resistance element 15 for acceleration detection in the X-axis direction in the way of connecting the resistance elements, and in this embodiment, extends in the X-axis direction. The resistance element 15 on the fixed portion 13 side provided in one of the two beam portions 12 and the resistance element 15 on the weight portion 11 side provided in the other beam portion 12 are connected by a wiring layer 16. A bridge circuit is configured by serial connection.

  When acceleration is applied to the sensor 10 in which such a bridge circuit is assembled, the beam portion 12 bends as described above, and the resistance element 15 is deformed in response to the deflection, so that the bridge circuit formed by the conductor layer 16 is used. The output voltage to be detected changes. The direction and magnitude of the applied acceleration can be detected by taking out the change in the output voltage based on the change in the resistance value as an electrical signal and processing it with an external IC.

  Further, the IC may be provided in the sensor 10. The resistance element 15 for detecting the acceleration in the Z-axis direction may be provided on the two beam portions 12 extending in the Y-axis direction in the same manner as that provided in the beam portion 12 extending in the X-axis direction.

  A pad electrode 14 that is electrically connected to the resistance element 15 is provided on the upper surface of the fixing portion 13, and the resistance elements 15 are connected to each other via the pad electrode 14 and the wiring layer 16. The signal is taken out.

(Acceleration sensor manufacturing method)
Next, a method for manufacturing the sensor 10 of the present invention will be described. Specifically, it is as follows.

Description will be made using an example in which an SOI substrate is used as the substrate. The SOI substrate includes an insulating layer, a semiconductor layer stacked on one side of the insulating layer, and a support layer stacked on the other side of the insulating layer. Insulating layer is formed, for example by SiO _2. The semiconductor layer is made of silicon. The support layer is made of, for example, a semiconductor such as silicon.

  First, a thermal oxidation process is performed on an SOI substrate at 1100 ° C. in an oxygen atmosphere until a thermal oxide film having a desired thickness is formed. Thereby, a thermal oxide film is formed on the entire outer periphery of the SOI substrate.

  Next, an impurity is implanted into the semiconductor layer through a thermal oxide film by ion implantation or the like, and annealing is performed at about 700 ° C., thereby forming a resistance element 15 made of a piezoresistor. As the impurities, B (boron) can be exemplified when the semiconductor layer uses an n-type SOI substrate, and P (phosphorus), As (arsenic), when the semiconductor layer uses a p-type SOI substrate, Examples thereof include Ph (phosphine). After forming the resistance element 15, a thermal oxide film is formed on the insulating layer 17 by patterning so that a part of the resistance element 15 is exposed. Next, a wiring layer 16 is formed which is connected to the piezoresistive element 15 exposed from the insulating layer 17 and routed on the insulating layer 17. The wiring layer 16 is formed by depositing a metal material such as aluminum by sputtering, CVD, vapor deposition or the like, and then patterning the deposited metal material by dry etching, wet etching, or the like. Thereafter, by performing a sintering process at about 400 ° C., the junction between the connection portion 16a of the wiring layer 16 and the resistance element 15 can be made ohmic.

  Next, by performing processing from the semiconductor layer side and the support layer side of the SOI substrate by a conventionally well-known semiconductor microfabrication technique, for example, photolithography method or reactive ion etching (RIE), the fixing portion 13, The weight part 11 and the beam part 12 are formed. In order to process the fixed portion 13, the weight portion 11, and the like in the thickness direction (Z-axis direction) perpendicular to one main surface, it is preferable to perform processing by inductively coupled plasma (ICP) RIE.

  Specifically, first, the semiconductor layer is removed in a region corresponding to a groove part that separates the weight part 11 and the fixed part 13. Next, the support layer is removed in the region corresponding to the groove and beam 12 described above.

  Further, the insulating layer is removed in a region corresponding to the groove. As described above, the groove portion penetrating the semiconductor layer, the insulating layer, and the support layer is formed, and the SOI substrate is divided into the inner peripheral side and the outer peripheral side by the groove portion, and the weight portion 11 and the fixing portion 13 are formed. The Further, the beam portion 12 is formed by the semiconductor layer in the intermittent portion of the groove portion (the portion where the groove portion is interrupted).

  Note that the SOI substrate has a larger area than the plurality of sensors 10, and the plurality of sensors 10 are formed from one SOI substrate in each of the above-described steps. Each process is basically performed in parallel for a plurality of sensors 10 on one SOI substrate. The SOI substrate is divided into a plurality of sensors 10 by, for example, dicing.

  As described above, the sensor 10 is formed by each process.

(Modification of the first embodiment)
Next, a modified example of the sensor 10 will be described with reference to FIG. The same applies to the following, but the same parts as those in FIG.

  A sensor 10 'shown in FIG. 2 is different from the sensor 10 shown in FIG. 1 in the configuration in which the wiring layer 16 and the resistance element 15 are electrically connected. Only the differences will be described below.

  In the sensor 10 shown in FIG. 1, the resistance element 15 and the connection portion 16 a of the wiring layer 16 are directly connected. On the other hand, the sensor 10 ′ is provided with an extension 18 extending from the resistance element 15 at the same thickness position (Z-axis position) as the resistance element 15, and the connection portion 16 a of the conductive layer 16 is connected to the extension 18. ing. Then, the resistance element 15 is disposed only in a portion where stress due to the displacement of the weight portion 11 of the beam portion 12 is concentrated, and the extending portion 18 is formed so as to straddle the first or second end of the beam portion 12 from there. 11 or the fixed portion 13. Thereby, the sensitivity with respect to acceleration can be raised. In addition, by increasing the conductivity of the extending portion 18 compared to the resistance element 15, the electrical loss is reduced even if the arrangement positions of the resistance element 15 and the connection portion 16a on the XY plane are separated from each other. Thus, the two can be electrically connected.

  Such an extension 18 can be formed by increasing the amount of impurities to be doped as compared with the resistance element 15, for example. In this case, the insulating layer 17 ′ may be formed by patterning a thermal oxide film so that the extending portion 18 is exposed.

  Moreover, the position of the extending part 18 in the thickness direction (Z-axis direction) may be at least partially overlapped with the thickness position where the resistance element 15 is disposed, and it is not necessary to match the thicknesses of the two. For example, the thickness of the extending portion 18 may be increased with respect to the thickness of the resistance element 15, and the upper surfaces of both may be arranged to be aligned.

  In this way, by connecting the resistance element 15 and the conductor layer 16 via the extension part 18 without directly connecting them, the connection position (position of the connection part 16a) with the conductor layer 16 where the step is generated is freely set. Can be adjusted. Thereby, the connection part 16a can be arrange | positioned in the area | region where there is little stress by the displacement of the weight part 11, and the failure | damage of the beam part 12 can be suppressed. Furthermore, it is also possible to increase the acceleration detection sensitivity by arranging the resistance element 15 only at a position where stress is concentrated.

  As described above, according to the sensor 10 ′ illustrated in FIG. 2, it is possible to provide an acceleration sensor with high reliability and high acceleration detection sensitivity.

(Second Embodiment)
Next, the sensor 20 which is other embodiment of this invention is demonstrated using FIG. FIG. 3 is an enlarged plan view of a main part in the vicinity of one beam portion 12 of the sensor 20. In order to facilitate understanding, the resistance element 15 and the extending portion 18 are hatched.

  The sensor 20 in FIG. 3 and the sensor 10 ′ shown in FIG. 2 differ in the means for reducing the stress due to the displacement of the weight portion 11 at the connection portion 16 a as compared with the resistance element 15.

  When the weight portion 11 is displaced, the stress is generally concentrated on the first end 12a and the second end 12b of the beam portion 12 depending on the shape of the beam portion 12. When the beam portion 12 is viewed on the XY plane, a stress distribution is generated such that the stress is reduced toward the middle 12c in the direction connecting the first end 12a and the second end 12b. Therefore, in the sensor 20 shown in FIG. 3, the resistance element 15 is folded in a U-shape (C-shape), and the resistance element 15 arranged near the first end 12a has a bent side at the first end. The resistor elements 15 arranged near the second end 12b are arranged so that the bent side is located at the second end 12b so as to be located at 12a. And the extending part 18 extended from the resistive element 15 is provided in the intermediate side 12c of the 1st end 12a and the 2nd end 12b of the beam part 12, and the connection part 16a is arrange | positioned on this extending part 18 Thus, the stress due to the displacement of the weight portion 11 is made smaller at the connection portion 16 a than the resistance element 15.

  By adopting such a configuration, damage to the beam portion 12 is suppressed, and a highly reliable sensor 20 is provided. For example, since there is no need to provide the connection portion 16a in the fixing portion 13, the width of the fixing portion 13 Can be reduced, and a small sensor 20 can be provided.

  In FIG. 3, the resistance element 15 and the conductor layer 16 are connected via the extending portion 18, but the extending portion 18 may not be provided. In that case, the connecting portion 16a may be connected to a portion of the resistance element 15 on the intermediate 12c side.

(Third embodiment)
Next, the sensor 30 which is other embodiment of this invention is demonstrated using FIG. FIG. 4A is an enlarged plan view showing the vicinity of one beam portion of the sensor 30. In the drawing, for easy understanding, the resistance element 15 and the extending portion 16 are hatched.

  The sensor 30 in FIG. 4A and the sensor 10 ′ shown in FIG. 2 differ in the means for reducing the stress due to the displacement of the weight portion 11 at the connection portion 16 a as compared with the resistance element 15.

  Specifically, a cross-sectional area changing portion 12d that increases in cross-sectional area toward the first end 12a and the second end 12b is formed in the beam portion 12. By such a cross-sectional area changing portion 12d, stress concentration on the connecting portion between the beam portion 12 and the fixed portion 13 and the connecting portion between the beam portion and the weight portion 11 is suppressed, and damage at the connecting portion of the beam portion 12 is suppressed. can do.

  And since the position (stress concentration part) where stress is most applied among the beam parts 12 is a part continuing from the cross-sectional area changing part 12d to the center 12c side, the resistance element 15 is arranged in this stress concentration part, and resistance An extending portion 18 extending from the element 15 to the cross-sectional area changing portion 12d is provided, and the extending portion 18 and the connecting portion 16a of the conductor layer 16 are connected in the cross-sectional area changing portion 12d. Thereby, since the stress due to the displacement of the weight portion 11 can be made smaller than that of the resistance element 15 at the connection portion 16a, damage to the beam portion 12 can be prevented, and a highly reliable sensor 30 can be provided.

  Such a cross-sectional area changing portion 12d is, for example, a portion in which the width of the cross-sectional area changing portion 12d gradually increases in XY plan view and the tangent line of the curve formed by the outer shape is connected to the beam portion 12 of the fixing portion 13. It is preferable that the angle formed by the side formed by the angle gradually decreases and becomes coincident as the first end 12a is approached. Specifically, it is preferable that the radius of curvature of the curve formed by the outer shape of the cross-sectional area changing portion 12d is equal to or greater than ¼ of the width w ′ of the beam portion 12. The same applies to the connection portion between the second end 12b and the weight portion 11.

  In this manner, by disposing the connection portion 16a in the cross-sectional area changing portion 12d of the beam portion 12, damage to the beam portion 12 can be suppressed. Moreover, since the area | region which arrange | positions the connection part 12a in the fixing | fixed part 13 becomes unnecessary, a small sensor can be provided.

  4A, the cross-sectional area changing portion 12d is realized by increasing the width of the beam portion 12 in the XY plane. However, as shown in FIG. 4B, the thickness direction (Z-axis) In FIG. 4, the cross-sectional area may be changed, or a combination of FIGS. 4A and 4B may be used. Here, when the cross-sectional area changing portion 12d is provided in the thickness direction, it is preferable that the curvature radius of the curve formed by the outer shape in a cross-sectional view is equal to or greater than ½ of the thickness t ′ of the beam portion 12.

  In FIG. 4, the resistance element 15 and the conductor layer 16 are connected via the extending part 18, but the extending part 18 may not be provided. In that case, the resistive element 15 may be extended to the cross-sectional area changing portion 12d and the connecting portion 16a may be connected.

(Deformation example of weight part)
1 to 4, the weight portion 11 has a substantially square planar shape, but four attached weights connected to the four corners of the weight portion 11 as in the sensor 10 '' shown in FIG. It is good also as a structure in which the part 21 was provided. In the drawing, the conductor layer 16 and the resistance element 15 for detecting the z-axis acceleration are not shown. The attached weight part 21 is formed integrally with the weight part 11, and by providing the attached weight part 21, the bending of the beam part 12 with respect to acceleration increases, and the detection sensitivity of acceleration can be improved.

  The length of one side in the plan view of the attached weight portion 21 is, for example, 0.1 mm to 0.4 mm. The thickness of the attached weight part 21 is the same as the thickness of the weight part 11, for example. Such an attached weight portion 21 may be devised for patterning so as to be formed at the same time when the weight portion 11 is formed by processing the SOI substrate.

  The sensors 10, 10 ′, 20, and 30 shown in FIGS. 1 to 4 have been described by taking the case where the weight portion 11 is made of a single material as an example. However, the material having a higher specific gravity than the material constituting the weight portion 11 is used. A separate weight member made of may be attached. In this case, when the same acceleration is applied, the amount of bending of the beam portion 12 increases, and a sensor element with higher sensitivity can be provided.

  Such a weight member is formed of iridium, osmium, platinum, rhenium, gold, tungsten, uranium, tantalum, palladium, ruthenium, thallium, lead, silver, molybdenum, lutetium, and bismuth if the weight portion 11 is silicon. For example, what is necessary is just to connect to the weight part 11 via adhesive members, such as a polyimide, an epoxy, and silicone.

  The present invention is not limited to the above embodiments and modifications, and may be implemented in various aspects.

  The acceleration sensor is not limited to one that measures triaxial acceleration. In addition, specific configurations such as the shape of the weight portion and the number of beam portions may be set as appropriate. For example, the acceleration sensor element may have only one or two beam portions and measure the acceleration of one axis by making it a cantilever shape. Further, instead of the SOI substrate, a Si substrate may be used. The shape of the beam portion may be a diaphragm shape.

DESCRIPTION OF SYMBOLS 10 ... Sensor 11 ... Weight part 12 ... Beam part 13 ... Fixed part 13a ... One main surface 14 ... Pad electrode 15 ... Resistance element 16 ... Conductive layer 16a ... Connection part 16b..Wiring part 17 ... Insulating layer 18 ... Extension part

Claims (7)

A fixed part;
A weight portion displaceable with respect to the fixed portion;
A beam portion having a first end connected to the fixed portion and a second end connected to the weight portion;
A resistance element that is disposed in the beam portion and has a resistance value that changes according to the deflection of the beam portion;
A conductor layer for connecting a resistance value of the resistance element to an external circuit,
A connection portion that is electrically connected to the resistance element and is disposed at a position where stress applied by displacement of the weight portion is smaller than that of the resistance element, and a surface that extends from the connection portion and extends to a thickness position different from that of the resistance element A conductive layer having a wiring portion disposed on
Accelerometer including. In a cross-sectional view, at the same thickness position as the resistance element, it further extends from the resistance element, and has an extended portion having higher conductivity than the resistance element,
The acceleration sensor according to claim 1, wherein the connection portion is connected to the extension portion. The acceleration sensor according to claim 1, wherein the connection portion is disposed on the fixed portion or the weight portion. The acceleration sensor according to claim 3, wherein the extension portion extends from the resistance element to the fixed portion or the weight portion. The said connection part is arrange | positioned at the said beam part, and is electrically connected to the said resistive element in the intermediate | middle side of the said 1st end and the said 2nd end of the said resistive element. Acceleration sensor. The beam portion has a cross-sectional area changing portion in which a cross-sectional area increases toward the first end or the second end,
The acceleration sensor according to claim 1, wherein the connection portion is disposed in the cross-sectional area changing portion. An insulating layer covering at least the resistance element and exposing the extension;
The acceleration sensor according to claim 2, wherein the wiring portion is disposed on the insulating layer.

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