JP2010139496A - Mems sensor and method for fixing mems sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a frame part is likely to be broken in production processes. <P>SOLUTION: An MEMS sensor includes: a flexible part; a weight part connected to one end of the flexible part and moving with the flexible part; a frame part circularly surrounding the weight part and having an inner circumference connected to the other end of the flexible part; and a circuit element including a detection means for detecting a deformation or displacement of the flexible part. The frame part includes: a substrate part; and a reinforcing part reinforcing the frame part, and the reinforcing part is a non-circuit element. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a MEMS (Micro Electro Mechanical System) sensor and a MEMS sensor fixing method.

  2. Description of the Related Art Conventionally, motion sensors such as fine acceleration sensors, angular velocity sensors, and vibration sensors manufactured using MEMS technology are known. These motion sensors include a flexible part called a beam, a weight part coupled to the flexible part, a frame part surrounding and supporting the flexible part and the weight part, and a deformation of the flexible part. Or a circuit element for detecting displacement. Patent Document 1 and Patent Document 2 describe an acceleration sensor having the above-described configuration and a method for manufacturing the acceleration sensor. In Patent Document 3, a cover member having a concave portion for fixing the motion sensor as described above is used, and the weight portion is bonded to the thick portion around the concave portion by bonding the bottom surface of the frame portion of the motion sensor. A configuration for securing the exercise space is described. Further, in Patent Document 4, when a motion sensor is attached to the flat surface of the base portion, an adhesive containing a filler is provided to obtain a motion space of the weight portion by providing a distance between the bottom surface of the weight portion and the base portion. Is applied to the bottom surface of the frame portion to fix the frame portion to the base portion.

JP 2002-296293 A JP 2008-060135 A JP-A-9-005353 JP 2000-0119196 A

In the conventional motion sensor manufactured using the MEMS technology, the frame portion is often constituted by a silicon wafer. However, for example, since silicon is a brittle material compared to a metal material, there is a problem that the frame portion is easily damaged in the manufacturing process of the motion sensor. Patent Document 2 discloses a configuration in which a plurality of through electrodes penetrating the frame portion in the thickness direction are formed. However, the through hole in which the through electrode is formed has a diameter of about 1 to 50 μm, and the through hole may be filled with a conductive material, or may be formed on the inner wall surface of the through hole and have a cavity. Is not described, and the structure is not expected to reinforce the frame portion. Moreover, when fixing a frame part after ensuring the exercise | movement space of the weight part of a motion sensor, it will lead to a cost increase if the raising member, such as glass in which the recessed part was formed like patent document 3, is used. On the other hand, in the structure of patent document 4, there exists a problem that the above-mentioned movement space cannot be controlled accurately depending on the filling state of a filler.
This invention is made | formed in view of said problem, Comprising: It makes it one of the objectives to make a frame part hard to damage in the manufacturing process of a MEMS sensor.

  (1) A MEMS sensor for achieving the above object includes a flexible part, a weight part that is coupled to one end of the flexible part, moves together with the flexible part, and surrounds the weight part in an annular shape. A frame portion having an inner periphery coupled to the other end of the flexible portion; and a circuit element including a detection unit that detects deformation or displacement of the flexible portion, wherein the frame portion includes a substrate portion and the frame. And a reinforcing part that reinforces the part.

  Compared with the conventional configuration in which the frame portion is not configured to include the reinforcing portion, and the portion of the material having the largest occupied volume in the frame portion is configured only by the substrate portion, the MEMS sensor of the present invention reinforces the frame portion. be able to. Therefore, it is possible to make the frame portion difficult to break in the manufacturing process of the MEMS sensor. In addition, according to the present invention, since the strength of the frame portion can be improved, the frame portion can be thinned, and the MEMS sensor can be reduced in size.

(2) In the MEMS sensor for achieving the above object, the reinforcing portion may be made of a material having higher toughness than the substrate portion.
Since the reinforcing portion has higher toughness than the substrate portion, the reinforcing portion is less likely to break than the substrate portion. The strength of the frame portion can be improved by including the reinforcing portion that is less likely to be damaged than the substrate portion.

(3) In the MEMS sensor for achieving the above object, the substrate portion may be made of a single crystal silicon wafer, and the reinforcing portion may be made of a metal material (metal or metal compound).
Metal materials are generally tougher and less likely to break than single crystal silicon. Therefore, the strength of the frame portion can be improved by including the reinforcing portion that is more difficult to break than the substrate portion.

(4) In the MEMS sensor for achieving the above object, the reinforcing portion may penetrate the substrate portion in the thickness direction.
The thicker the reinforcing part provided in the frame part, the more difficult it is to break the frame part. Therefore, when the reinforcement part which penetrates a board | substrate part in the thickness direction is formed in the frame part, the effect which reinforces a frame part can be heightened.

(5) In the MEMS sensor for achieving the above object, the reinforcing portion may constitute a surface layer on an outer peripheral side surface of the frame portion.
According to the present invention, it is possible to make the frame part difficult to chip in the manufacturing process of the MEMS sensor.

(6) In the MEMS sensor for achieving the above object, the reinforcing portion may make a round in the frame portion.
According to the present invention, since the reinforcing part is formed at one place without seeing the board part when viewed in the thickness direction, the frame part is formed in the manufacturing process of the MEMS sensor as compared with the case where the reinforcing part is formed by breaking. Becomes difficult to break.

(7) In the MEMS sensor for achieving the above object, the reinforcing portion may constitute a corner portion of the frame portion.
According to the present invention, the corner portion of the frame portion can be made difficult to chip in the manufacturing process of the MEMS sensor.

(8) In the MEMS sensor for achieving the above object, the bottom surface of the weight portion that faces the base portion that fixes the frame portion may recede from the bottom surface of the reinforcing portion that faces the base portion. .
According to the present invention, since the bottom surface of the weight portion is configured to recede from the bottom surface of the reinforcing portion, when the bottom surface of the reinforcing portion of the MEMS sensor is attached to the flat surface of the base portion, the bottom surface of the weight portion and the base portion An interval can be provided between them. This interval functions as a part of the movement space of the weight part. Compared to a conventional configuration in which a gap is provided between the base portion and the bottom surface of the weight portion by bonding the frame portion and the base portion using an adhesive containing filler, the interval can be controlled with high accuracy. Moreover, in this invention, when attaching the bottom face of a frame part to a base part, since the raising member which formed the recessed part is not required, an increase in cost can be suppressed.

(9) In the MEMS sensor for achieving the above object, the bottom surface of the substrate portion facing the base portion may recede from the bottom surface of the reinforcing portion.
In particular, the entire side surface of the substrate portion is covered with the reinforcing portion (including both the case where the substrate portion makes a circle around the frame portion and the case where the substrate portion exists in a columnar shape or an island shape within the frame portion). ) When a concave portion is formed with the bottom surface of the substrate portion as the bottom surface and the side surface of the reinforcing portion as the inner wall surface, if the adhesive is applied to the concave portion and the frame portion is fixed to the base portion, the reinforcement that does not face the concave portion Adhesive is difficult to ooze out to the side of the part. Therefore, it is difficult for the adhesive to adhere to the weight portion. Even when the outer peripheral side surface of the reinforcing portion is covered with the substrate portion and the bottom surface of the substrate portion is recessed from the bottom surface of the reinforcing portion, a recess is formed. When attached to the base part, the adhesive is difficult to protrude to the weight part side.

  (10) A MEMS sensor fixing method for achieving the above-mentioned target is as follows. An adhesive is applied to a recess formed in a frame portion of the MEMS sensor as described below, and the frame portion is bonded to the base portion by the adhesive. Including fixing to. The MEMS sensor includes a flexible portion, a weight portion that is coupled to one end of the flexible portion, moves together with the flexible portion, and surrounds the weight portion in an annular shape, and has an inner circumference at the other end of the flexible portion. A circuit element including a frame part that is coupled to the frame part and includes a reinforcing part that reinforces the frame part and a substrate part, and detection means that detects deformation or displacement of the flexible part. And the bottom surface of the weight portion facing the base portion that fixes the frame portion recedes from the bottom surface of the reinforcing portion facing the base portion, and the side surface of the substrate portion covers the reinforcing portion. The bottom surface of the substrate portion facing the base portion is retracted from the bottom surface of the reinforcing portion facing the base portion, so that the bottom surface of the substrate portion is the bottom surface and the side surface of the reinforcing portion is the inner surface. A concave portion as a wall surface is formed in the frame portion.

  As in the present invention, when the adhesive is applied to the concave portion and the frame portion is fixed to the base portion, the adhesive is less likely to ooze out of the concave portion. Therefore, it is difficult for the adhesive to adhere to the weight portion. Further, according to the present invention, since the bottom surface of the weight part recedes from the bottom surface of the reinforcing part, the base part and the weight part are bonded by bonding the frame part and the base part using an adhesive containing a filler as in the prior art. There is no need to provide a gap between the bottom surface. In the present invention, the interval can be accurately controlled as compared with the configuration in which the interval is provided by the adhesive containing filler. Moreover, in this invention, when attaching the bottom face of a frame part to a base part, since the raising member which formed the recessed part is not required, an increase in cost can be suppressed.

(1A) is sectional drawing of the acceleration sensor concerning 1st embodiment, (1B) is a top view. (2A) is sectional drawing for demonstrating the principal part of the acceleration sensor concerning 1st embodiment, (2B) is a top view. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 1st embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 1st embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 1st embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 1st embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 1st embodiment. (8A) is sectional drawing for demonstrating the principal part of the acceleration sensor concerning 2nd embodiment, (8B) is a top view. (9A) is sectional drawing for demonstrating the principal part of the acceleration sensor concerning 3rd embodiment, (9B) is a top view. (10A) is a cross-sectional view for explaining the main part of the acceleration sensor according to the fourth embodiment, and (10B) is a plan view. The top view which shows the modification of 4th embodiment. The top view which shows the modification of 4th embodiment. (13A) is sectional drawing for demonstrating the principal part of the acceleration sensor concerning 5th Embodiment, (13B) is a top view. Sectional drawing which shows the acceleration sensor concerning 5th embodiment. Sectional drawing which shows the acceleration sensor concerning 5th embodiment. The top view which shows the modification of 5th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 5th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 5th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 5th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 5th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 5th embodiment. Sectional drawing for demonstrating the principal part of the acceleration sensor concerning 6th embodiment. Sectional drawing which shows the acceleration sensor concerning 6th embodiment. Sectional drawing which shows the modification of 6th embodiment. The top view which shows the modification of 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing for demonstrating the manufacturing process of the acceleration sensor concerning 6th embodiment. Sectional drawing which shows the modification of 6th embodiment.

  Hereinafter, embodiments of the present invention will be described in the following order with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.

1. First embodiment (Configuration)
An acceleration sensor 1 as a first embodiment of a MEMS sensor of the present invention is shown in FIGS. 1A, 1B, 2A, and 2B. 1B is a plan view of the acceleration sensor 1 as viewed from the front surface (surface on which the wiring portion 31 is formed), and FIG. 1A is a cross-sectional view taken along line AA of FIG. 1B. 2A and 2B are diagrams for explaining mechanical components of the acceleration sensor 1, and the boundaries between the components are indicated by solid lines. In FIG. 2A and FIG. 2B, circuit elements such as detection means and wiring portions are omitted. 2B is a plan view of the acceleration sensor 1 viewed from the back side, and FIG. 2A is a cross-sectional view taken along line AA in FIG. 2B.

  The acceleration sensor 1 includes a frame portion S having a rectangular frame shape in plan view, four flexible portions F respectively coupled to the inside of the frame portion S, and a weight portion coupled to the four flexible portions F. M, the piezoresistive element 130, and the wiring part 31b are provided. The acceleration sensor 1 is a MEMS sensor that detects acceleration by converting deformation of the flexible portion F according to the force acting on the weight portion M into an electrical signal by the piezoresistive element 130.

As shown in FIG. 1A, each component of the acceleration sensor 1 is a thicker layer of an SOI (Silicon On Insulator) wafer, a bulk layer 11 made of single crystal silicon, a metal layer 10 made of a metal material, and an SOI wafer. The connecting layer 12 is an insulating layer made of silicon dioxide (SiO ₂ ), the semiconductor layer 13, the insulating layer 20 made of silicon dioxide, and the wiring layer on which the wiring portion 31b is formed. That is, the acceleration sensor 1 is a solid element having a thin film laminated structure.

  As shown in FIGS. 1A, 1B, 2A, and 2B, the flexible portion F includes an insulating layer 20 and a semiconductor layer 13. The weight portion M includes a bulk layer 11, a connection layer 12, a semiconductor layer 13, and an insulating layer 20. The weight part M has a quadrangular prism shape in the present embodiment. The thickness of the bulk layer 11 is about 625 μm, for example. The thickness of the connection layer 12 is 1 μm, and the thickness of the semiconductor layer 13 is 10 μm. The thickness of the insulating layer 20 is sufficiently thinner than the semiconductor layer 13, for example, 0.3 μm.

  A plurality of contact holes H1 for the piezoresistive portion 131 are formed in the insulating layer 20. A piezoresistive element 130 (piezoresistive portion 131 and contact resistance reducing portion 132) is formed on the surface layer of the semiconductor layer 13 (the surface that does not face the bulk layer 11 is the front). The remainder of the semiconductor layer 13 is made of single crystal silicon (Si). Boron (B) ions are implanted into the piezoresistive portion 131 as silicon impurities. The contact resistance reducing unit 132 is continuous with both ends of the piezoresistive unit 131. Boron ions are implanted into the contact resistance reducing unit 132 as silicon impurities at a higher concentration than the piezoresistive unit 131. In the contact hole H1, the contact resistance reducing portion 132 and the wiring portion 31b are coupled. The wiring part 31 b and the piezoresistive part 131 are electrically connected via the contact resistance reducing part 132. The wiring part 31b is made of aluminum (Al).

  As impurities implanted into the piezoresistive element 130, phosphorus (P), arsenic (As), or the like can be used in addition to boron. The piezoresistive element 130 functions as “detecting means” described in the claims. A piezoelectric element may be used as the detection means. The piezoresistive element 130 and the wiring part 31b function as “circuit elements”.

  Each of the four flexible portions F is in the form of a thin film-like beam protruding toward the weight portion M located at the center of the inner space of the frame portion S having a rectangular frame shape. Since the inertial force acts on the weight part M coupled to the protruding ends of the four flexible parts F, each flexible part F is deformed. By detecting the bending of two flexible portions F aligned in a straight line, the acceleration component in the direction parallel to the straight line (x direction and y direction) and the acceleration component in the thickness direction (z direction) of the flexible portion F Can be detected. In the present embodiment, a total of 12 piezoresistive portions 131 (four on each axis) are provided in the semiconductor layer 13 in the vicinity of the surface layer of the four flexible portions F in order to detect the three-axis components orthogonal to each other. Yes.

  The frame part S surrounding the flexible part F and the weight part M is composed of a substrate part S1, a reinforcing part S2, a connection layer 12, a semiconductor layer 13, and an insulating layer 20. The substrate portion S1 corresponds to a “substrate portion made of a single crystal silicon wafer” described in the claims. The substrate part S1 is composed of the bulk layer 11. The reinforcing portion S2 is made of the metal layer 10. Examples of the material of the metal layer 10 constituting the reinforcing portion S2 include Ni, Cu, Fe—Ni alloy, Mg—Zr alloy, Mn—Cu alloy, and the like, in particular, the inside of Mg—Zr alloy, Mn—Cu alloy, etc. By using a metal material with a large loss, high-frequency vibration can be quickly damped by the reinforcing portion S2. The reinforcing part S2 is not connected to the circuit element, and therefore the reinforcing part S2 is a non-circuit element. The substrate portion S1 has a rectangular frame shape when viewed from the thickness direction of the bulk layer 11. The reinforcing portion S2 covers the entire side surface on the outer peripheral side of the rectangular frame-shaped substrate portion S1. That is, the reinforcing portion S2 is formed to have the same thickness as the substrate portion S1, and is formed in an annular shape (in the shape of a rectangular frame outside the substrate portion S1) so as to surround the weight portion M. In FIG. 1B, a wide broken line 30 represents a boundary between the substrate portion S1 and the reinforcing portion S2. When viewed from the thickness direction of the substrate portion S1, the width W1 of the frame portion S is about 300 μm, and the width W2 of the reinforcing portion S2 is about 100 to 150 μm.

  Metal materials have higher toughness than single crystal silicon. Therefore, the frame portion S is not configured to include the reinforcing portion S2 made of a metal material, and the portion of the material having the largest occupied volume in the frame portion S is composed only of the substrate portion S1 made of a single crystal silicon wafer. Compared with the configuration, the frame portion S can be reinforced in the acceleration sensor of the present embodiment.

  Moreover, in this embodiment, since the reinforcement part S2 is formed in the same thickness as the board | substrate part S1, the effect which reinforces the frame part S can be heightened. Further, in the present embodiment, since the reinforcing portion S2 is formed at one place without seeing the substrate portion S1 in the thickness direction, the frame portion S is compared with the case where the reinforcing portion S2 is formed to be cut off. The strength of can be increased. Further, since the outer peripheral side surface of the substrate portion S1 is covered with the reinforcing portion S2, the strength of the frame portion S can be improved (prevention of chipping) against an impact on the outer peripheral side surface of the frame portion S.

  As described above, since the frame portion S can be reinforced by the reinforcing portion S2, the frame portion S can be thinned, and the MEMS sensor 1 can be downsized. Next, a method for manufacturing the MEMS sensor 1 will be described. By increasing the strength of the frame portion S, it is possible to make the frame portion difficult to break during the manufacturing process.

(Production method)
First, a step of forming impurities by injecting impurities into the thinner semiconductor layer 13 of the SOI wafer, a step of etching the semiconductor layer 13 and the insulating layer 20 in accordance with the shape of the flexible portion F, A step of forming the wiring portion 31b to the resistance element 130 is performed. These steps are described in JP-A No. 2002-296293, JP-A No. 9-171333, JP-A No. 8-274349, JP-A No. 8-201068, JP-A No. 2005-106679, JP-A No. 2006-317242. Since it is publicly known as disclosed in Japanese Patent Laid-Open No. 2006-170962, etc., description thereof is omitted. Then, the process for forming the reinforcement part S2 of the frame part S and the weight part M in the state which adhere | attached the workpiece | work on the reinforcement board | substrate is demonstrated, referring FIGS.

First, the surface of the workpiece (the surface on which the wiring part 31b is formed) is bonded to a reinforcing substrate (not shown). For example, wax is used as the adhesive. You may adhere | attach a workpiece | work to the reinforcement board | substrate which is not shown in figure with a photoresist, a double-sided adhesive tape, etc. Subsequently, as shown in FIG. 3, the bulk layer 11 is anisotropically etched using the protective film R <b> 1 made of a photoresist, thereby forming an annular recess H <b> 2 in the bulk layer 11 and exposing the connection layer 12. The recess H2 is a mold that is filled with a metal material that forms the reinforcing portion S2. The bulk layer 11 is etched by deep-RIE (so-called Bosch process) in which, for example, passivation with C ₄ F ₈ plasma and etching with SF ₆ plasma are repeated alternately.

  Subsequently, after removing the protective film R1, as shown in FIG. 4, the recess H2 is filled with the metal layer. For example, the metal layer 10 composed of an adhesion metal layer and a main metal layer is formed. Specifically, the adhesion metal layer is formed by, for example, sputtering by depositing the first metal material. The adhesion metal layer is formed on the bottom surface and the side surface of the recess H2 by sputtering. Subsequently, a main metal layer is formed by depositing a second metal material thicker than the adhesion metal layer on the surface of the adhesion metal layer. The main metal layer is formed by electrolytic plating, for example. CVD, electroless plating, or the like may be used for depositing the second metal material. As the second metal material, for example, Ni, Cu, Fe—Ni alloy, Mg—Zr alloy, Mn—Cu alloy or the like is used. For example, chromium (Cr) is used as the first metal material.

Next, as shown in FIG. 5, the surface layer of the metal layer 10 is removed by grinding or polishing until the bulk layer 11 is exposed. In this step, the bulk layer 11 is processed to a finished thickness.
Next, as shown in FIG. 6, an annular recess H3 is formed in the bulk layer 11 by anisotropically etching the bulk layer 11 using Deep-RIE or the like using the protective film R2 made of a photoresist, and the connection layer 12 is formed. Expose.
Next, as shown in FIG. 7, the connecting layer 12 is etched to expose the semiconductor layer 13, whereby the flexible portion F, the frame portion S, and the weight portion M are formed. For example, anisotropic dry etching with a reactive gas is used to etch the connection layer 12. When post-processes such as removal of the protective layer R2 and dicing are performed, the acceleration sensor 1 shown in FIG. 1 is completed. In this embodiment, since the outer peripheral side surface of the substrate portion S1 is covered by the reinforcing portion S2, it is resistant to an impact from the outer peripheral side surface and is not easily damaged. For example, in the dicing process, since the substrate portion S1 does not directly contact the cutter, chipping hardly occurs. Further, when the cutter comes into contact with the reinforcing portion S2, the strength of the reinforcing portion S2 is strong, so that the chipping and breakage of the frame portion S hardly occur.

2. Second embodiment (Configuration)
FIG. 8A and FIG. 8B show mechanical components of the acceleration sensor 2 as a second embodiment of the MEMS sensor of the present invention. In FIG. 8A and FIG. 8B, the boundary of each component is shown with the continuous line, and circuit elements, such as a detection means and a wiring part, are abbreviate | omitted. 8B is a plan view of the acceleration sensor 2 viewed from the back side, and FIG. 8A is a cross-sectional view taken along the line AA of FIG. 8B. In the frame part S of the acceleration sensor 2, the entire inner side surface and the entire outer side surface of the substrate part S1 are covered with the reinforcing part S2. The thickness of the substrate part S1 and the thickness of the two reinforcing parts S2 are formed to be the same. Since the entire inner side surface and the entire outer side surface of the substrate part S1 are covered with the reinforcing part S2, the stress is balanced in the frame part S and deformation (warping) of the frame part S is suppressed. Can do.

(Production method)
In order to form the two reinforcing portions S2 covering the inner peripheral side surface and the outer peripheral side surface of the substrate portion S1 in the frame portion S, the bulk layer 11 is formed in order to form the reinforcing portion S2 in the first embodiment. What is necessary is just to change the pattern of the protective film used when etching. That is, the opening pattern of the protective film R1 for forming the recess H2 is shaped to match the two reinforcing portions S2 having a rectangular frame shape as shown in FIG. 8B.

3. Third Embodiment (Configuration)
FIG. 9A and FIG. 9B show mechanical components of the acceleration sensor 3 as a third embodiment of the MEMS sensor of the present invention. In FIG. 9A and FIG. 9B, the boundary of each component is shown with the continuous line, and circuit elements, such as a detection means and a wiring part, are abbreviate | omitted. FIG. 9B is a plan view of the acceleration sensor 3 as viewed from the back side, and FIG. 9A is a cross-sectional view taken along line AA of FIG. 9B. In the frame portion S of the acceleration sensor 3, the entire inner side surface of the substrate portion S1 is covered with the reinforcing portion S2. The thickness of the substrate part S1 and the thickness of the two reinforcing parts S2 are formed to be the same.

(Production method)
In order to form the reinforcement part S2 which covers the side surface of the inner peripheral side of the substrate part S1 in the frame part S, the protective film used when the bulk layer 11 is etched to form the reinforcement part S2 in the first embodiment. What is necessary is just to change the pattern. That is, the pattern of the opening of the protective film R1 for forming the concave portion H2 is made to conform to the rectangular frame-shaped reinforcing portion S2 as shown in FIG. 9B.

4). Fourth embodiment (Configuration)
FIG. 10A and FIG. 10B show mechanical components of the acceleration sensor 4 as the fourth embodiment of the MEMS sensor of the present invention. In FIG. 10A and FIG. 10B, the boundary of each component is shown with the continuous line, and circuit elements, such as a detection means and a wiring part, are abbreviate | omitted. 10B is a plan view of the acceleration sensor 4 viewed from the back side, and FIG. 10A is a cross-sectional view taken along the line AA of FIG. 10B. In the frame portion S of the acceleration sensor 4, the reinforcing portion S2 penetrates the inside of the substrate portion S1 in the thickness direction, and the reinforcing portion S2 is formed in an annular shape surrounding the weight portion M (around the frame portion S). ing). Since the contact area between the substrate part S1 and the reinforcing part S2 is large, the reinforcing part S2 is unlikely to fall off the substrate part S1.

  11 and 12 show a modification of the fourth embodiment. Although the reinforcing portion S2 penetrates the substrate portion S1 in the thickness direction, as shown in FIG. 11 or FIG. 12, the reinforcing portion S2 is not formed in an annular shape when viewed from the thickness direction of the substrate portion S1. May be. In the modification shown in FIG. 12, the reinforcing portion S <b> 2 constitutes a part of the corner portion of the frame portion S. According to this structure, the corner | angular part of the frame part S can be made hard to chip with the reinforcement part S2. In addition, the reinforcement part S2 may comprise the surface layer of the corner | angular part of the frame part S. FIG.

(Production method)
In order to form the reinforcing part S2 that penetrates the inside of the substrate part S1 in the thickness direction, the pattern of the protective film used when the bulk layer 11 is etched to form the reinforcing part S2 in the first embodiment is changed. do it. That is, the opening pattern of the protective film R1 for forming the recess H2 is shaped to match the reinforcing part S2 as shown in FIG. 10B, FIG. 11 or FIG.

5). Fifth embodiment (Configuration)
FIG. 13A and FIG. 13B show mechanical components of the acceleration sensor 5 as a fifth embodiment of the MEMS sensor of the present invention. In FIG. 13A and FIG. 13B, the boundary of each component is shown as the continuous line, and circuit elements, such as wiring parts other than a detection means and a penetration electrode, are abbreviate | omitted. 13B is a plan view of the acceleration sensor 5 as seen from the back side, and FIG. 13A is a cross-sectional view taken along the line AA of FIG. 13B. The frame portion S of the acceleration sensor 5 is formed with a plurality of reinforcing portions S2 penetrating the substrate portion S1 and a plurality of through electrodes E penetrating the frame portion S. The diameter of the through electrode is about 30 μm. For example, as shown in FIG. 14, the acceleration sensor 5 in which the through electrode is formed is placed so that the external electrode 142 and the through electrode E formed on the bottom surface of the package 150 are aligned. The through electrode E and the external electrode 142 are joined by a solder ball 141. A spacer 140 having a height equivalent to the height of the solder ball 141 is provided in a portion where the external electrode is not formed, and supports the acceleration sensor 5. The external electrode 142 may pass through the bottom of the package 150 as shown in FIG. 14, or may pass through the side wall as shown in FIG. FIG. 16 shows a modification of the fifth embodiment.

Thus, by providing the through electrode E in the frame portion S and forming the reinforcing portion S2 in the frame portion S to improve the strength of the frame portion S and reduce the width of the frame portion S, the acceleration sensor It is possible to reduce the size of the package that accommodates the battery.
In the above example, the connection between the piezoresistive portion 131 and the through electrode E is connected via the contact resistance reducing portion 132 and the wiring portion 31b formed on the surface of the solid element of the acceleration sensor 5. You may make it connect by a bonding wire.

(Production method)
After performing the step of forming the piezoresistive element 130, the step of etching the semiconductor layer 13 and the insulating layer 20 in accordance with the form of the flexible portion F, and the step of forming the wiring portion 31b to the piezoresistive element 130, As shown in FIG. 17, a film 143 serving as an etching stopper is formed on the surface where the wiring part 31b is formed. Subsequently, as shown in FIG. 17, a through hole H4 penetrating from the bulk layer 11 side to the wiring part 31b is formed by ICP-RIE using a protective film R3 made of a photoresist. Alternatively, the through hole H4 may be formed by sandblasting, wet etching, or femtosecond laser. Next, an oxide film is formed on the bottom and side surfaces of the through hole H4. As the oxidation method, dry oxidation or wet oxidation is used.

  Next, after forming an adhesion metal layer on the bottom and side surfaces of the through hole H4 by, for example, plasma CVD, the through hole H4 is filled with a conductive metal by electrolytic plating, electroless plating, etc., as shown in FIG. The through electrode E is formed. Thereafter, the adhesion metal layer and the conductive metal layer are ground or polished until the bulk layer 11 is exposed.

  Next, as shown in FIG. 19, a recess H5 is formed in the bulk layer 11 by, for example, Deep-RIE using a protective film R4 made of a photoresist, and the connection layer 12 is exposed. Subsequently, as shown in FIG. 20, after forming a close-contact metal layer in the recess H5, the recess H5 is filled with the main metal layer by electrolytic plating, electroless plating, or the like, thereby forming a prototype of the reinforcing portion S2 made of the metal layer 10. Form. Thereafter, the adhesion metal layer and the main metal layer are ground or polished until the bulk layer 11 is exposed.

  Next, the recess H6 is formed in the bulk layer 11 by, for example, Deep-RIE using the protective film R5 made of photoresist, and the connection layer 12 is exposed. Subsequently, the connection layer 12 is removed, and the semiconductor layer 13 is exposed. The connection layer 12 can be removed, for example, by dry etching using a reactive gas. Through the above steps, the weight portion M, the frame portion S, and the flexible portion F are formed. The acceleration sensor 5 is completed through subsequent processes such as removal of the etching stopper film 143 and the protective film R5 and dicing.

6). Sixth embodiment (Configuration)
FIG. 22 shows mechanical components of the acceleration sensor 6 as a sixth embodiment of the MEMS sensor of the present invention. In FIG. 22, the boundary of each component is shown with the continuous line, and circuit elements, such as a detection means and a wiring part, are abbreviate | omitted. A plan view of the acceleration sensor 6 seen from the back side is the same as FIG. 8B. 22 is a cross-sectional view taken along line AA in FIG. 8B. That is, as in the second embodiment, the acceleration sensor 6 of the present embodiment has a configuration in which the entire side surface on the inner peripheral side and the entire side surface on the outer peripheral side of the substrate portion S1 are covered with the reinforcing portion S2 in the frame portion S. ing. The acceleration sensor 6 is different from the acceleration sensor 2 of the second embodiment in that the bottom surface of the substrate portion S1 and the bottom surface of the weight portion M are retracted from the bottom surface of the reinforcing portion S2 (here, the bottom surface is a frame (Refers to the surface facing the base portion such as the bottom of the package that fixes the portion S). Therefore, an annular recess H7 is formed in the frame portion S of the acceleration sensor 6 when viewed from the bottom surface direction. The acceleration sensor 6 according to the sixth embodiment has the following effects in addition to the effects exhibited by the acceleration sensor 2 according to the second embodiment.

  Since the bottom surface of the weight portion M is retracted from the bottom surface of the reinforcing portion S2, as shown in FIG. 23, when the frame portion S is attached to a flat surface such as the bottom portion (base portion) of the package 150, A distance d can be provided between the bottom surface of the weight part M and the flat surface. By providing the distance d, it is possible to provide an exercise space on the bottom surface side of the package 150 from the position of the weight M in the stationary state. When fixing the frame S to the bottom of the package 150, it is not necessary to use a spacer 140 or a raising member having a recess, so that an increase in cost can be suppressed. Further, when the acceleration sensor 6 is attached to the bottom surface of the package 150, if the adhesive 145 is applied to the annular recess H7 and adhered to the bottom surface of the package, the reinforcing portion S2 becomes a wall and the adhesive 145 becomes the concave portion of the reinforcing portion S2. Difficult to ooze out to the side facing H7. Therefore, the trouble that the adhesive 145 adheres to the weight portion M hardly occurs.

  FIG. 24 is a diagram illustrating a modification of the sixth embodiment. A plan view of the acceleration sensor of this modification viewed from the back side is the same as FIG. 10B. 24 is a cross-sectional view taken along line AA in FIG. 10B. That is, in this modified example, the reinforcing portion S2 goes around the inside of the frame portion S (the side surface of the reinforcing portion S2 is covered by the substrate portion S1), and the bottom surface of the substrate portion S1 is from the bottom surface of the reinforcing portion S2. Retreating. Further, the bottom surface of the weight portion M is also retracted from the bottom surface of the reinforcing portion S2. For example, the adhesive is applied to the recess 146 (the recess 146 formed on the outer peripheral side of the reinforcing portion S2 by the bottom surface of the substrate portion S1 covering the outer peripheral side surface of the reinforcing portion S2 being retracted from the bottom surface of the reinforcing portion S2). When attached to the base part, the adhesive hardly protrudes to the weight part side.

  FIG. 25 is a view showing a modification of the sixth embodiment, and shows a plan view of the acceleration sensor as seen from the back side. The substrate part S1 is formed in an island shape at the four corners of the frame part S. The entire side surface of the island-shaped substrate portion S1 is covered with the reinforcing portion S2. In the frame portion S, the substrate portion S1 is divided by the reinforcing portion S2 and has an island shape. The bottom surface of the substrate portion S1 is recessed from the bottom surface of the reinforcing portion S2, and a recess H7 is formed. The bottom part of the weight part M is also retracted from the bottom part of the reinforcing part S1.

  Manufacturing method 1 and manufacturing method 2 will be described as a method for manufacturing the above-described form in which the bottom portion of substrate portion S1 is retracted from the bottom portion of reinforcing portion S2. By adopting these methods, the distance d can be accurately controlled. In the manufacturing method 1 and the manufacturing method 2, a method for manufacturing the acceleration sensor 6 shown in FIG. 22 will be described. The acceleration sensor manufacturing method of FIGS. 24 and 25, which is a modified example thereof, is different only in that the pattern for forming the reinforcing portion S2 is changed, and thus the description thereof is omitted.

(Manufacturing method 1)
The following manufacturing method 1 is effective when the thickness of the weight portion M is made thinner than the thickness of the SOI substrate. In the process of FIG. 3, the pattern of the protective film used when the bulk layer 11 is etched to form the reinforcing part S2 in the first embodiment is matched to the shape of the reinforcing part S2 as shown in FIG. 8B. In other words, a recess for forming the reinforcing portion S2 is formed. Thereafter, the metal layer 10 is filled as in the step of FIG. The method for forming the metal layer 10 can be the same method as in the first embodiment. In addition, for example, sputtering or CVD (Chemical Vapor Deposition) may be employed. Subsequently, as in the step of FIG. 5, the metal layer 10 is removed by grinding or polishing until the bulk layer 11 is exposed.

  Subsequently, as shown in FIG. 26, the bulk layer 11 is anisotropically etched using the protective film R6 made of a photoresist, thereby forming a recess having a predetermined depth in the bulk layer 11. The bottom surface of the recess formed at this time becomes the bottom surface of the weight portion M and the bottom surface of the substrate portion S1 in the acceleration sensor 6 in a completed state. Moreover, the recessed part of the bulk layer 11 enclosed by the metal layer 10 among the recessed parts formed at this time is the outer peripheral side surface of the recessed part H7 (inner annular metal layer 10 (reinforcing part S2)) in FIGS. The inner peripheral side surface of the outer annular metal layer 10 (reinforcing portion S2) is the inner wall surface, and the exposed surface of the bulk layer 11 surrounded by these two annular metal layers 10 (the bottom surface of the substrate portion S1) is the bottom surface. , A recess). The depth of the recess formed by anisotropic etching corresponds to the distance d in FIGS. For anisotropic etching, for example, Deep-RIE is employed. Therefore, the interval d can be controlled with high accuracy. After the etching, the protective film R6 is removed.

  Subsequently, as shown in FIG. 27, by using the protective film R7 made of a photoresist, the bulk layer 11 is anisotropically etched by Deep-RIE or the like to form an annular recess H8 in the bulk layer 11, and the connection layer 12 is exposed. Next, the protective layer R7 is removed, the exposed connection layer 12 is removed by wet etching, and the semiconductor layer 13 is exposed, whereby the acceleration sensor 6 shown in FIG. 22 (FIG. 28) is completed.

(Manufacturing method 2)
In order to prevent the thickness of the weight M from being thinner than the thickness of the SOI substrate, the following manufacturing method 2 is effective. Before the step of FIG. 26 described in the above manufacturing method 1, that is, after the metal layer 10 is formed and ground or polished until the bulk layer 11 is exposed, as shown in FIG. A metal layer 14 is formed on the surfaces of the metal layer 10 and the bulk layer 11. For example, the adhesion metal layer is formed by sputtering, and the metal layer 14 is formed by forming a main metal layer thicker than the adhesion metal layer by plating on the surface of the adhesion metal layer. For example, Cr can be used as the material of the adhesion metal layer. As the material of the main metal layer, Ni, Cu, Fe—Ni alloy, Mg—Zr alloy, Mn—Cu alloy, or the like can be used. The thickness of the metal layer 14 corresponds to the distance d shown in FIG. According to the manufacturing method 2, the thickness of the metal layer 14 can be precisely controlled by the plating time.

  Next, a protective layer R8 made of a photoresist is formed on the surface of the metal layer 14, and the metal layer 14 is removed using the protective layer R8 (removed except for the surface portion of the metal layer 10) as shown in FIG. ) To expose the bulk layer 11. At this time, two annular metal layers 14 projecting from the surface of the bulk layer 11 are formed. That is, the outer peripheral side surface of the inner annular metal layer 14 and the inner peripheral side surface of the outer annular metal layer 14 are inner walls, and the exposed surface of the bulk layer 11 surrounded by these two annular metal layers 14 is the bottom surface. It will be in the state in which the recessed part H7 was formed.

  Subsequently, the protective layer R8 is removed. Subsequently, as shown in FIG. 31, an annular recess H9 is formed in the bulk layer 11 by anisotropically etching the bulk layer 11 with Deep-RIE or the like using a protective layer R9 made of a photoresist, and a connection layer 12 is exposed. Next, as shown in FIG. 32, the connection layer 12 is etched, the semiconductor layer 13 is exposed, and the protective layer R9 is removed, whereby the acceleration sensor 6 of FIG. 22 is completed. The reinforcing portion S <b> 2 of the acceleration sensor 6 manufactured by the manufacturing method 2 includes the metal layer 10 and the metal layer 14.

  Note that the acceleration sensor 6 shown in FIG. 22 may be manufactured by performing the following steps instead of the steps shown in FIG. Before the step of FIG. 26 described in the manufacturing method 1, that is, after the metal layer 10 is formed and ground or polished until the bulk layer 11 is exposed, the surfaces of the metal layer 10 and the bulk layer 11 are processed. A metal adhesion layer is formed on the substrate. Subsequently, a protective layer made of a photoresist is formed on the surface of the metal adhesion layer. The protective layer is a mask pattern that exposes the metal adhesion layer in the projected region of the metal layer 10 and covers the other regions. Subsequently, a main metal layer thicker than the metal adhesion layer is formed on the surface of the exposed metal adhesion layer by plating. At this time, the distance d shown in FIG. 22 can be controlled by adjusting the thickness of the main metal layer. Subsequently, by removing the protective layer and removing the exposed metal adhesion layer, the acceleration sensor 6 shown in FIG. 22 can be manufactured.

  A configuration in which the bottom surface of the frame portion S is kept flat without forming the recess H7 or the depression 146, and the bottom surface of the weight portion M is retracted from the bottom surface of the frame portion S (for example, FIG. 33). Is included in the scope of rights. The configuration shown in FIG. 29 uses the protective layer in which the opening for forming the recess H7 is not formed in the step of FIG. 26 described above, and only the bottom surface of the weight portion M is etched by the depth d. It can manufacture by implementing a process. When bonding the frame S and the bottom of the package 150, it is not necessary to secure an exercise space of the weight M by using a filler-containing adhesive. Further, it is not necessary to use a raising member having a spacer or a concave portion in order to secure the movement space of the weight portion M.

7). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the acceleration sensor is described as an example of the MEMS sensor. However, the present invention may be applied to other motion sensors (an angular velocity sensor, a vibration sensor, and the like) including a flexible portion, a weight portion, and a frame portion. The materials, dimensions, shapes, film forming methods, and pattern transfer methods shown in the above embodiment are merely examples, and the addition and deletion of processes and the replacement of process order that are obvious to those skilled in the art are described. It is omitted.

  1-5: acceleration sensor, 10: metal layer, 11: bulk layer, 12: connection layer, 13: semiconductor layer, 14: metal layer, 20: insulating layer, 30: broken line, 31b: wiring part, 130: piezoresistor Element: 140: Spacer, 141: Solder ball, 142: External electrode, 143: Etching stopper film, 145: Adhesive, 150: Package, E: Through electrode, F: Flexible part, H1: Contact hole, H2: Recess , H3: recessed portion, H4: through hole, H5 to H9: recessed portion, M: weight portion, R1 to R9: protective film, S: frame portion, S1: substrate portion, S2: reinforcing portion.

Claims (10)

A flexible part;
A weight portion coupled with one end of the flexible portion and moving with the flexible portion;
A frame part that surrounds the weight part in an annular shape and has an inner periphery coupled to the other end of the flexible part;
A circuit element including detection means for detecting deformation or displacement of the flexible portion;
With
The frame portion includes a substrate portion and a reinforcing portion that reinforces the frame portion.
MEMS sensor. The reinforcing portion is made of a material having higher toughness than the substrate portion.
The MEMS sensor according to claim 1. The substrate portion is composed of a single crystal silicon wafer, and the reinforcing portion is composed of a metal material.
The MEMS sensor according to claim 1 or 2. The reinforcing part penetrates the substrate part in the thickness direction,
The MEMS sensor according to any one of claims 1 to 3. The reinforcing portion constitutes a surface layer of the outer peripheral side surface of the frame portion.
The MEMS sensor according to any one of claims 1 to 3. The reinforcing part makes a round in the frame part,
The MEMS sensor according to any one of claims 1 to 5. The reinforcing part constitutes a corner of the frame part,
The MEMS sensor according to any one of claims 1 to 5. The bottom surface of the weight portion facing the base portion fixing the frame portion is recessed from the bottom surface of the reinforcing portion facing the base portion.
The MEMS sensor according to any one of claims 1 to 7. The bottom surface of the substrate portion facing the base portion is recessed from the bottom surface of the reinforcing portion.
The MEMS sensor according to claim 8. A flexible part;
A weight portion coupled with one end of the flexible portion and moving with the flexible portion;
A frame portion that annularly surrounds the weight portion and has an inner periphery coupled to the other end of the flexible portion, and includes a reinforcing portion that reinforces the frame portion and a substrate portion. When,
A circuit element including detection means for detecting deformation or displacement of the flexible portion;
With
The bottom surface of the weight portion facing the base portion fixing the frame portion is recessed from the bottom surface of the reinforcing portion facing the base portion,
The side surface of the substrate portion is covered with the reinforcing portion, and the bottom surface of the substrate portion facing the base portion is set back from the bottom surface of the reinforcing portion facing the base portion. A MEMS sensor fixing method in which a recess having a bottom surface as a bottom surface and a side surface of the reinforcing portion as an inner wall surface is formed in the frame portion,
An adhesive is applied to the recess, and the frame is fixed to the base by the adhesive;
Fixing method of MEMS sensor.

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