JP2010197270A - Method of manufacturing acceleration sensor element and acceleration sensor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly productive method of manufacturing an acceleration sensor of high detection accuracy. <P>SOLUTION: This method includes: an A process for forming a fixed part comprising a sloped wall by working a substrate so that the horizontal cross-section of the substrate is smaller on the other principal plane side as compared with one principal plane side, the sloped wall having a slope domain in which an inner wall surface confronting a support is sloped; a B process for fixing a weight on the support with it put into contact with the slope domain of the sloped wall; and a C process for removing the surface of the slope domain of the sloped wall by etching to provide a gap between the weight and the sloped wall. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention relates to an acceleration sensor element manufacturing method and an acceleration sensor element.

  An acceleration sensor device that detects acceleration using a piezoresistance effect is known (for example, Patent Document 1). The acceleration sensor device of Patent Document 1 includes a weight fixing portion, a beam portion that supports the weight fixing portion, a fixing portion that supports the beam portion, a piezoresistive element provided on the beam portion, and a weight fixing portion. And a separate weight fixed to the body. Here, the weight fixing portion and the weight are combined to form a weight portion. When an external force proportional to the acceleration is applied to the acceleration sensor device, 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-2005-351716

  In the above-described acceleration sensor device, as the mass of the weight portion is increased, the deflection of the beam portion with respect to the acceleration increases, and the acceleration detection sensitivity increases. And since the weight part which has a desired mass is realizable by bonding the weight which has a desired mass, the detection sensitivity of acceleration can be controlled, without changing the size of an acceleration sensor apparatus. However, if the arrangement position of the weight is shifted, the bending method of the beam portion is changed, and the acceleration detection accuracy is deteriorated. In addition, a correction circuit that compensates for variations in detection accuracy for each acceleration sensor element is required, which reduces productivity.

  The objective of this invention is providing the manufacturing method and acceleration sensor element which manufacture the acceleration sensor element with high productivity, maintaining the detection accuracy of acceleration.

  The acceleration sensor element manufacturing method of the present invention includes a support portion, a fixed portion surrounding the support portion, a beam portion connected between the support portion and the fixed portion, and a weight member connected to the support portion. And a method of manufacturing an acceleration sensor element that detects acceleration by bending of the beam portion, and processes the substrate to surround the support portion in order from the main surface side of the substrate in the thickness direction. A connecting portion connected to the beam portion, and an inclined region in which an inner wall surface facing the support portion is inclined so that a cross-sectional area in the horizontal direction is smaller on the other principal surface side than the one principal surface side of the substrate. A step of forming a fixed portion having a thicker wall than the support portion and the beam portion, and the support in a state where the weight member is in contact with the inclined region of the inclined wall portion. B step to be fixed to the part, and the inclined region of the inclined wall part The surface of the is removed by etching, and has a, a C step of providing a gap between said weight member and said inclined wall portion.

  In the acceleration sensor element of the present invention, the cross-sectional shape gradually decreases on the support portion, the frame-shaped connection portion surrounding the support portion, and the inner peripheral surface facing the support portion in order from the thickness direction. In this way, the fixed portion having the inclined region inclined and the inclined wall portion having the vertical region in which the cross-sectional shape following the inclined region is constant, one end is connected to the connection portion of the fixed portion, and the other end is the A beam part connected to a weight part; a resistance element provided on the beam part, the resistance value of which changes with the deflection of the beam part; and the inclined area of the fixed part, with a gap therebetween, and the support A weight member fixed to the portion.

  According to the method for manufacturing an acceleration sensor element of the present invention, when the weight member is fixed to the support portion, the weight member is automatically positioned by being brought into contact with the inclined wall portion. Can be arranged. Thereby, stable performance can be expressed without variation in detection accuracy for each acceleration sensor element. Then, by removing the surface of the inclined region of the inclined wall portion and providing a gap between the weight member and the inclined wall portion, the weight member arranged at a desired position can be displaced according to the acceleration from the outside, and the acceleration It functions as a sensor element. From the above, it is possible to provide a method for manufacturing an acceleration sensor element with high productivity while maintaining the detection accuracy of the acceleration sensor element.

  In addition, according to the acceleration sensor element of the present invention, an acceleration sensor with high detection accuracy and reliability can be provided. In addition, since the inclined region is formed over the entire thickness direction of the inclined wall portion, the outer shape required to secure the space necessary for arranging the weight member of the same size can be reduced. The acceleration sensor element can be reduced in size.

It is a perspective view of the acceleration sensor element produced with the manufacturing method of the acceleration sensor element of this invention. (A)-(e) is sectional drawing explaining each process of the manufacturing method of the acceleration sensor element of this invention, respectively. The shape of the fixed part in the manufacturing method of FIG. 2 will be described, (a) and (b) are plan views of the substrate as viewed from the bottom, and (c) are perspective views. (A), (b) is sectional drawing explaining A1 and A2 process which are the modification of the manufacturing method of FIG. 2, respectively. (A), (b) is sectional drawing of the acceleration sensor element produced by the manufacturing method of the acceleration sensor element which concerns on embodiment of this invention, respectively.

  Exemplary embodiments of an acceleration sensor element manufacturing method and an acceleration sensor element according to the present invention will be explained below in detail with reference to the drawings. Note that the drawings used in the following embodiments are schematic, and the dimensional ratios in the drawings do not necessarily match the actual ones. 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.

  The acceleration sensor element 20 (hereinafter simply referred to as a sensor element) will be described. FIG. 1 is a perspective view of the sensor element 20. As shown in FIG. 1, the sensor element 20 includes a support part 11, a frame-like fixing part 13 surrounding the support part 11, one end connected to the fixing part 13, and the other end connected to the support part 11. It has a beam portion 12, an element-side electrode pad 14 formed on the fixed portion 13, a resistance element 15 formed on the beam portion 12, and a weight member 16 connected to the support portion 11.

  When acceleration is applied to the sensor element 20, a force corresponding to the acceleration acts on the support portion 11 and the weight member 16 (hereinafter, these may be collectively referred to as the weight portion 17), and the weight portion 17 moves. Thus, the beam portion 12 is bent.

  The weight part 17 in the present embodiment is provided with four attached weight parts 21 connected to the four corners thereof. The attached weight portion 21 is formed integrally with the weight portion 17, and by providing the attached weight portion 21, the bending of the beam portion 12 with respect to acceleration increases, and the detection sensitivity of acceleration can be improved. Moreover, since the area for joining the support part 11 and the weight member 16 can be taken large, joining strength can be made high. In addition, the weight part 17 and the attached weight part 21 whole may be grasped | ascertained as a weight part. Moreover, since the structure, function, and formation method of the weight part 17 and the attached weight part 21 are the same or similar, description of the attached weight part 21 may be omitted below.

The present embodiment is characterized in that the weight member 16 is arranged on the support portion 11 with high positional accuracy. Hereinafter, each process will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing each step of the method for manufacturing the sensor element 20.
<Board Preparation Step: Formation of Resistance Element 15>
In the present embodiment, an example in which an SOI (Silicon on Insulator) substrate is used as a substrate will be described. As shown in FIG. 2A, surface processing is performed on one main surface 27 a of the SOI substrate 27. The SOI substrate 27 includes an insulating layer 24, a semiconductor layer 25 stacked on one side of the insulating layer 24, and a support layer 26 stacked on the other side of the insulating layer 24. Insulating layer 24 is formed, for example by SiO _2. The semiconductor layer 25 is made of silicon. The support layer 26 is made of, for example, a semiconductor such as silicon. The surface processing is processing on the semiconductor layer 25 on the main surface 27a of the SOI substrate 27 on the semiconductor layer 25 side.

  Specifically, the resistance element 15 made of piezoresistance is formed by implanting impurities into the semiconductor layer 25 by ion implantation. Examples of the impurities include B (boron) when the semiconductor layer 25 uses an n-type SOI substrate, and P (phosphorus) and As (arsenic) when the semiconductor layer 25 uses a p-type SOI substrate. And the like. After the resistor element 15 is formed, a wiring connected to the piezoresistive element is formed. The wiring is formed by forming a metal material such as aluminum by metal sputtering, CVD, vapor deposition or the like and then patterning the formed metal material by dry etching, wet etching, or the like.

(Step A; formation of the fixing portion 13)
Next, as shown in FIG. 2B, an SOI substrate is formed by a conventionally well-known semiconductor microfabrication technique such as photolithography or inductively coupled plasma reactive ion etching (ICP-RIE). 27 is formed from the semiconductor layer 25 side and the support layer 26 side to form the fixing portion 13. In addition, since it is preferable to form the support part 11 and the beam part 12 simultaneously, these methods are also demonstrated.

  Specifically, first, the semiconductor layer 25 is removed in a region corresponding to a groove portion that divides the support portion 11 and the fixing portion 13. Next, the support layer 26 is removed in a region corresponding to the groove part, the support part 11, and the beam part 12. Here, on the inner wall surface 30 facing the support portion 11 of the fixed portion 13, the inclined region 31 is inclined so that the horizontal cross-sectional area becomes smaller on the main surface 27 b side in the thickness direction of the substrate 27 than on the main surface 27 a side. Form. The inclined region 31 is obtained, for example, by etching the support layer 26 made of Si by anisotropic etching. The etchant can be appropriately selected from tetramethylammonium hydroxide aqueous solution (TMAH), KOH and the like depending on the crystal orientation of the support layer 26. For example, KOH may be used when the crystal orientation of the support layer 26 is 100 planes.

  Further, the insulating layer 24 is removed in a region corresponding to the groove. As described above, a groove portion penetrating the semiconductor layer 25, the insulating layer 24, and the support layer 26 is formed, and the SOI substrate 27 is divided into an inner peripheral side and an outer peripheral side by the groove portion, and the support portion 11 and the fixing portion 13 are separated. And are formed. Further, the beam portion 12 is formed by the semiconductor layer 25 in the intermittent portion of the groove portion (the portion where the groove portion is interrupted).

  Here, the fixing portion 13 is disposed on the main surface 27a side with respect to the thickness direction of the substrate 27, and is disposed on the main surface 27b side of the connection portion 13a and the connection portion 13a connected to the beam portion 12. The inclined wall portion 13b having the inclined region 31 is configured. As a result, the fixed portion 13 is set to be thicker than the support portion 11 and the beam portion 12.

  In the example shown in FIG. 2 (b), the insulating layer 24 is exposed on the main surface 27b side of the support portion 11, but the support layer is within the range thinner than the thickness of the inclined wall portion 13b. 26 may be present.

(Step B; fixing the weight member 22)
Next, as illustrated in FIG. 2C, the adhesive 22 is disposed on the main surface 27 b side of the support portion 11. Subsequently, as shown in FIG. 2 (d), the support portion 11 and the weight member 16 are joined by the adhesive 22 in a state where the weight member 16 is disposed in contact with the inclined region 31. Here, the weight member 16 is supported by the inclined region 16 at at least three points, and is fixed in a state of being automatically arranged at a desired position. As described above, by providing the inclined region 16, the positioning of the weight member 16 with respect to the support portion 11 can be easily performed.

(Step C; formation of gap d)
Next, as shown in FIG. 2E, the surface of the inclined region 31 is removed by etching to form a gap d between the weight member 16 and the fixed portion 13. An etchant that can remove only the support layer 26 without damaging the weight member 16 and the adhesive 22 may be selected. For example, when the support layer 26 is made of silicon and molybdenum is used as the weight member 16 and a resin material such as polyimide, epoxy, or silicone is used as the adhesive 22, KOH can be used as an etchant. Thereby, the support layer 26 can be anisotropically etched.

  Further, the size of the gap d can be appropriately set as long as the weight member 16 can be displaced. For example, the lower limit may be set in consideration of the sensitivity of the acceleration sensor element and the acceleration detection range, and the upper limit may be set in consideration of damage caused by displacement caused by excessive acceleration. Thereby, the weight member 16 can be displaced according to the force generated by the acceleration. As described above, the sensor element 20 is formed by each process.

  The SOI substrate 27 has a larger area than the plurality of sensor elements 20, and the plurality of sensor elements 20 are formed from one SOI substrate 27 in each of the above-described steps. Each process is basically performed in parallel on a plurality of sensor elements 20 of one SOI substrate 27. Then, after the C process, the SOI substrate 27 is divided into a plurality of sensor elements 20.

  3A and 3B are views for explaining the shape of the inclined wall portion 13b in the step A. FIGS. 3A and 3B are views of the substrate 27 viewed from the main surface 27b side (from the lower side), and FIG. FIG. 3 is a perspective view of a substrate 27. In FIG. 3, some components other than the components of the fixing unit 13 are omitted for explanation.

As shown in FIG. 3A, the inclined region 31 may be provided over the entire inner peripheral surface facing the support portion 11. In addition, as shown in FIG. 3B, inclined regions 31 may be provided at four locations so as to correspond to the four sides of the support portion 11. In this case, the support layer 26 is left so as to have a thickness equivalent to that of the inclined wall portion 13b in a portion where the inclined region 31 is not present (for example, a corner portion of the fixed portion 13). In FIG. 3B, the inclined regions 31 are provided so as to correspond to the four sides of the support part 11, but may be provided at positions corresponding to the four corners of the support part 11. In FIG. 3C, the inclined region 31 is disposed at a position corresponding to the four corners of the support portion 11 (a position where the beam portion 12 is not formed), and is supported at a position other than the positions corresponding to the four corner portions. An example in which the layer 26 is removed is shown. By setting it as such a structure, the inclination area | region 31 does not exist in the part to which the beam part 12 is connected to the connection part 13a of the fixing | fixed part 13. FIG. Thereby, the element size required for arranging the weight members 16 having the same size can be reduced.
(Modification 1)
A modification of the method of forming the inclined wall portion 13b of the fixed portion 13 will be described with reference to FIG. FIG. 4 is a cross-sectional view showing a modification of the process shown in FIG.
(Step A1)
Following the step shown in FIG. 2A, the support layer 26 of the substrate 27 is etched from the main surface 27b side by ICP-RIE to form the first recess 40. The first recess 40 has a bottom surface 40a formed of the support layer 26 and a first inner wall surface 40b perpendicular to the main surface 27b on the inner periphery.
(Step A2)
Subsequent to the step A1, the second recess 41 is formed on the bottom surface 40a of the first recess 40 by wet etching. The second recess 41 has a bottom surface 41b made of the insulating layer 25 and a second inner wall surface 41b that is inclined so that the cross-sectional shape is smaller on the main surface 27b side than on the main surface 27a side on the inner peripheral portion. The second inner wall surface 41b is formed following the first inner wall surface 40b. Inclining the second inner wall surface 41b can be realized by performing anisotropic etching as described in FIGS. 2 (b) and 2 (e).

  Then, the second inner wall surface 41b formed in the step A2 is used as the inclined region 31, so that each step after FIG. 2C is performed, and an acceleration sensor element as shown in FIG. 5B is manufactured. Can do.

  In addition, by passing through such A1 process and A2 process, the inner wall surface of the inclined wall part 13b of the fixing | fixed part 13 is perpendicular | vertical area | region perpendicular | vertical to the main surface 27b of the board | substrate 27 in order from the main surface 27b side of the board | substrate 27 ( The first inner wall surface 40b) and the inclined region 31 (41b) connected to the vertical region 40b are provided.

With such a configuration, the size of the substrate 27 necessary for arranging the weight members 16 of the same size can be reduced, and the acceleration sensor element can be downsized.
(Modification 2)
In the step shown in FIG. 2, the inclined region 31 of the inclined wall portion 13 b is in a state in which the support layer 26 is exposed. In the step A, however, after the substrate 27 is processed into the same shape as in FIG. A layer is formed on the wall surface 30, and the weight member 16 is disposed in contact with this layer in the step B, and this layer is removed in the step C, so that the weight member 16 is fixed between the fixing member 13 and the weight member 16. The acceleration sensor element may be manufactured so as to provide a gap.

In this case, the inclined region is constituted by a layer provided on the support layer 26. The material of this layer is not limited as long as it can be removed by etching in the C step. For example, a resin or an inorganic material can be used. For example, in the case where the layer is made of a resin, an asher treatment may be performed. In the present specification, such an ashing process of the resin is included in the etching.
(Summary)
Since the acceleration sensor element manufactured by the method as described above can easily align the weight member 16 with high accuracy, the detection accuracy is stable and the productivity is high.
(Configuration of acceleration sensor element)
Next, the acceleration sensor element manufactured by the above-described method will be described in detail with reference to FIG. 1 and FIG. FIG. 5A is a cross-sectional view of an acceleration sensor element manufactured by the method shown in FIG.

  The support portion 11 has a substantially square planar shape, and the length of one side thereof is set to, for example, 0.25 mm to 0.5 mm. Moreover, the thickness of the support part 11 is set to 5 micrometers-20 micrometers, for example. The attached weight portion 21 has a substantially square shape in the same manner as the support portion 11, and the length of one side thereof is set to 0.1 mm to 0.4 mm, for example. Further, the thickness of the attached weight portion 21 is set to, for example, 5 μm to 20 μm so as to have the same thickness as the support portion 11. The thickness of the attached weight portion 21 may be different from the thickness of the support portion 11. The planar shape of the support portion 11 and the attached weight portion 21 is not limited to a square, and can be any shape such as a circle or a rectangle. The support part 11 and the attached weight part 21 are integrally formed by processing the SOI substrate 27, for example.

  A frame-shaped fixing portion 13 is formed so as to surround the support portion 11 and the attached weight portion 21. The fixed portion 13 has a substantially square plane shape, and has a substantially square opening that is slightly larger than the support portion 11 and the attached weight portion 21 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 constituting the connecting portion 13a of the fixed portion 13 (width in a direction perpendicular to the longitudinal direction of the arm; w in FIG. 1). Is set to 0.1 mm to 1.8 mm, for example. Moreover, the thickness (t of FIG. 1) of the fixing | fixed part 13 is set to 0.2 mm-0.625 mm, for example.

  An adhesive 22 is disposed on the back surface of the support portion 11, and the weight member 16 is fixed to the support portion 11 by the adhesive 22.

  The adhesive 22 is not particularly limited as long as it can join the supporting portion 11 and the weight member 16 and is not damaged by the etchant in the etching process described above. For example, polyimide, epoxy, silicone, or the like is used. Can be used.

  The material of the weight member 16 may be appropriately selected so that the weight portion 17 obtains a desired mass. However, in order to increase the acceleration detection sensitivity with the same size, a material having a specific gravity greater than that of the support portion 11 is used. It is preferable to use it. For example, while the support portion 11 is made of silicon, the weight member 16 is made of iridium, osmium, platinum, rhenium, gold, tungsten, uranium, tantalum, palladium, ruthenium, thallium, lead, silver, molybdenum, lutetium. And bismuth.

  The shape and size of the weight member 16 may be set as appropriate. A cylindrical shape, a rectangular parallelepiped shape, a cylinder having a different size, or a shape in which rectangular solids are stacked may be used. In order to increase the sensitivity to acceleration, the size is preferably as large as possible, and is larger than the support portion 11 within a range that can be disposed with a gap from the inclined wall portion 13b. The thickness of the weight member 16 is set to be equal to the thickness of the support layer 26 of the SOI substrate 27, for example. However, when the sensor element 20 is mounted, when the main surface 27b of the fixed portion 13 is disposed on a flat substrate, the bottom surface of the weight member 16 (connected to the adhesive 22 is secured to ensure a movable range. It is preferable to set the thickness such that the surface opposite to the side) is disposed closer to the main surface 27a than the main surface 27b of the support layer 26.

  A beam portion 12 is provided between the fixed portion 13 and the support 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 support portion 11 and the other end connected to the central portion on the upper surface side of each side in the inner periphery of the fixed portion 13. In the sensor element 20, four beam portions 12 are provided.

  The beam portion 12 has flexibility. When acceleration is applied to the sensor element 20, the weight portion 17 moves, and the beam portion 12 bends as the weight portion 17 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, the resistor element 15 is a piezoresistive element formed by implanting boron into the n-type SOI substrate 27 in the semiconductor layer 25. 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 fixed portion 13 side are connected in series, the resistance elements arranged on the support portion 11 side are connected in series, and these are connected in parallel. This constitutes 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 circuit 15 is arranged in the same manner, and a bridge circuit is configured by connecting the resistor elements.

  Although not shown, four resistance elements 15 for detecting the acceleration in the Z-axis direction are provided on the two beam portions 12 extending in the X-axis direction for detecting the acceleration in the X-axis direction. The resistor elements 15 are formed so as to be lined 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. A resistance element 15 on the fixed portion 13 side provided in one of the two beam portions 12 and a resistance element 15 on the support portion 11 side provided in the other beam portion 12 are connected in series. A bridge circuit is configured.

  When acceleration is applied to the sensor element 20 in which such a bridge circuit is assembled, the beam portion 12 is bent as described above, and the resistance element 15 is deformed in accordance with the bending, so that the output voltage detected by the bridge circuit changes. To do. 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 acceleration sensor element. 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.

  An element-side electrode pad 14 that is electrically connected to the resistance element 15 is provided on the upper surface of the fixed portion 13, and the resistance elements 15 are connected to each other and the electric power from the resistance element 15 is connected via the element-side electrode pad 14. The signal is taken out.

  According to the above embodiment, the sensor element 20 can position and fix the weight member 16 to the support portion 11 with high accuracy. For example, when the inclined wall portion 13b of the fixed portion 13 is formed by photolithography, the weight member 16 can be positioned with an accuracy equivalent to that of photolithography.

  In addition, since the weight member 16 is fixed via the insulating layer 24, the weight member 16 hardly exerts an electrical influence on the semiconductor layer 25 even if a conductive material is used as the weight member 16. Therefore, the range of selection of the material of the weight member 16 can be expanded.

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

  For example, an Si substrate may be used instead of the SOI substrate. The shape of the beam portion may be a diaphragm shape.

  The acceleration sensor element is not limited to the one that measures the acceleration in the triaxial direction. For example, the acceleration sensor element may measure acceleration in one axis direction. The support part may not have an attached weight part.

DESCRIPTION OF SYMBOLS 11 ... Support part 12 ... Beam part 13 ... Fixed part 13a ... Connection part 13b ... Inclined wall part 14 ... Element side electrode pad 15 ... Resistance element 16 ... Weight member 20 ... Sensor element 22 ... Adhesive 31 ... Inclined area

Claims (5)

A support part, a fixing part surrounding the support part, a beam part connected between the support part and the fixing part, and a weight member connected to the support part, and acceleration is caused by bending of the beam part. A method of manufacturing an acceleration sensor element to detect,
A substrate is processed, and in order from the one main surface side of the substrate in the thickness direction, the support portion is surrounded and connected to the beam portion, and the other main surface as compared with the one main surface side of the substrate A fixed portion having a thicker thickness than the support portion and the beam portion, and an inclined wall portion having an inclined region in which an inner wall surface facing the support portion is inclined so that a cross-sectional area in the horizontal direction is reduced on the side. A step to be formed;
B step of fixing the weight member to the support portion in a state where the weight member is in contact with the inclined region of the inclined wall portion;
And a C step of removing a surface of the inclined region of the inclined wall portion by etching to provide a gap between the weight member and the inclined wall portion. The method of manufacturing an acceleration sensor element according to claim 1, wherein the inclined wall portion is formed so as to surround an entire circumference of a region where the support portion is disposed. The method of manufacturing an acceleration sensor element according to claim 1, wherein the weight member is made of a material having a specific gravity larger than that of the material forming the support portion. The other main surface side of the substrate is made of Si,
The inner wall surface of the inclined wall portion has the inclined region and the subsequent vertical region perpendicular to the other main surface of the substrate from one main surface side to the other main surface side of the substrate,
The inclined wall portion is
In the step A, a part of the substrate is removed by ICP-RIE in a region made of Si on the other main surface side of the substrate, and a first inner wall surface perpendicular to the other main surface of the substrate is formed in the inner peripheral portion. A1 step of forming a first recess having
After the step A1, a part of the substrate on the bottom surface of the first recess is removed by wet etching, and the main surface side of the substrate is different from the main surface side of the substrate, following the first inner wall surface. Forming the second recess having the second inner wall surface such that the cross-sectional shape of the surface side becomes smaller, and the A2 step,
The method for manufacturing an acceleration sensor element according to any one of claims 1 to 3, wherein the first inner wall surface is the vertical region, and the second inner wall surface is the inclined region. A support part;
In order from the thickness direction, a frame-shaped connecting portion that surrounds the support portion, an inclined region that is inclined so that the cross-sectional shape gradually decreases on the inner peripheral surface facing the support portion, and a subsequent cross-sectional shape are constant An inclined wall having a vertical region, and a fixed part having
A beam portion having one end coupled to the connection portion of the fixed portion and the other end coupled to the weight portion;
A resistance element provided in the beam portion, the resistance value of which changes with the deflection of the beam portion;
A weight member that is disposed with a gap from the inclined region of the fixing portion and is fixed to the support portion;
An acceleration sensor element.

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