JP2010175359A - Mems inclination sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MEMS (Micro-Electro-Mechanical Systems) inclination sensor being ready for miniaturization, in particular, and having high detection accuracy. <P>SOLUTION: This MEMS inclination sensor 1 includes a support substrate, a cap substrate, and an intermediate layer positioned between the support substrate and the cap substrate. The intermediate layer has a turning weight 11 and a turning shaft 12, the turning shaft 12 put through a through hole formed in the turning weight 11 and fixed/supported on the support substrate and on the cap substrate. The turning weight 11 is supported so that it can turn around toward the gravitational direction. A magnet 8 is placed on the turning weight 11. A pair of magnetism detection elements 4 and 5 are placed in an opposite domain of the cap substrate to a turning domain 22 of the turning weight 11. When rotating the inclination sensor 1 clockwise or anticlockwise from a reference state, the electric characteristics of one magnetism detection element positioned on a side approaching the magnet 8 changes due to an external magnetic field received from the magnet 8. Based on the change in the electric characteristics, the state of rotation can be found. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a tilt sensor formed using MEMS (Micro-Electro-Mechanical Systems) technology.

  The following patent document discloses a tilt sensor. The tilt sensor includes a magnet that is rotatably supported and a detection unit that detects an external magnetic field from the magnet.

All of the tilt sensors described in these patent documents have a mechanical configuration (mechanical type), and the miniaturization of the tilt sensor cannot be promoted, resulting in an increase in manufacturing cost. In addition, it was necessary to improve detection accuracy without causing malfunction due to a disturbance magnetic field.
JP 2006-300789 A JP 2006-126059 A JP 2007-118868 A JP 2006-78406 A

  Therefore, the present invention solves the above-described conventional problems, and in particular, an object of the present invention is to provide a MEMS tilt sensor that can cope with downsizing and obtain high detection accuracy.

The present invention relates to a MEMS tilt sensor including a magnet and a magnetic detection element that is arranged in a non-contact manner with the magnet and changes an electric characteristic in response to an external magnetic field from the magnet.
A first substrate, a second substrate, and an intermediate layer located between the first substrate and the second substrate;
The intermediate layer includes a rotating weight, and a rotating shaft that is inserted into a through-hole formed in the rotating weight and is fixedly supported by the first substrate and the second substrate. Is supported so that it can rotate in the direction of gravity,
The magnet is installed on the rotating weight, and the magnetic detection element is installed in a region facing the first substrate with respect to the rotating area of the rotating weight,
In the reference state of the MEMS tilt sensor, the magnetic detection elements are disposed on both sides of a center line drawn in parallel to the direction of gravity through the center of the rotation shaft,
When the MEMS tilt sensor is rotated clockwise or counterclockwise from the reference state, the rotating weight rotates and maintains a constant posture in the gravity direction, while the magnetic detection element is rotated clockwise or counterclockwise. The magnetic detection element that rotates in the direction and approaches the magnet at this time receives an external magnetic field from the magnet, and changes its electrical characteristics, and the rotation state can be known based on the change in electrical characteristics. To do.

  In the present invention, since the tilt sensor is configured by using the MEMS technology, the size can be reduced and the production cost can be reduced.

  In the present invention, a fixed resistance element that constitutes an electric circuit with the magnetic detection element is provided outside the opposing region of the first substrate, and the fixed resistance element has the same element configuration as the magnetic detection element. Is preferred.

  As described above, since the magnetic detection element and the fixed resistance element can all be formed with the same element configuration, the manufacturing efficiency can be improved, and the manufacturing cost can be reduced more effectively. Even if a disturbance magnetic field acts, the electrical characteristics change of the magnetic detection element and the fixed resistance element is the same, output fluctuation can be suppressed, and malfunction is unlikely to occur.

In the present invention, the magnetic detection element includes an element portion whose electric resistance value changes with respect to an external magnetic field from the sensitivity axis direction,
The element portion has a laminated structure in which a first magnetic layer and a second magnetic layer are laminated via a nonmagnetic layer,
Both the first magnetic layer and the second magnetic layer can change magnetization with respect to the external magnetic field,
In the absence of a magnetic field, the magnetization direction of the first magnetic layer is inclined from the reference direction orthogonal to the sensitivity axis direction to the first direction of the sensitivity axis direction, and the magnetization direction of the second magnetic layer is The second magnetic layer is inclined from the reference direction in a second direction opposite to the first direction in the sensitivity axis direction, the angle between the magnetization direction of the first magnetic layer and the reference direction, and the second magnetic layer And the reference direction are substantially the same angle, and the angle between the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer is in the range of 90 degrees to 180 degrees. Within
The element portion is formed in an elongated shape having the sensitivity axis direction as a longitudinal direction, and the magnet and the magnetic detection element are opposed to each other by rotating the MEMS tilt sensor clockwise or counterclockwise from a reference state. It is preferable that the arrangement of the magnet and the element portion is regulated so that the magnetizing direction of the magnet coincides with the longitudinal direction of the element portion.

  More preferably, the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer are substantially antiparallel toward a direction parallel to the sensitivity axis direction.

  With the magnetic detection element having the above-described configuration, even if an external magnetic field other than the sensitivity axis direction acts, the change in electric resistance is small, the disturbance magnetic field resistance can be improved, and the detection accuracy can be improved. In addition, in the case of the magnetic detection element having the above-described configuration, each magnetic detection element exhibits almost the same resistance change even when the magnetization direction of the magnet is reversed. Therefore, the output characteristics are almost the same regardless of the magnetization direction of the magnet. Can be obtained.

  According to the present invention, since the tilt sensor is configured using the MEMS technology, the size can be reduced and the production cost can be reduced. Furthermore, disturbance magnetic field tolerance can be improved, and detection accuracy can be improved.

  FIG. 1 is a perspective front view of the MEMS tilt sensor in the present embodiment, FIG. 2 is a cross-sectional view of the MEMS tilt sensor taken along the line AA shown in FIG. 1 and viewed from the direction of the arrow, and FIG. FIG. 4 is a perspective front view of the MEMS tilt sensor when the MEMS tilt sensor is rotated 90 degrees clockwise from the reference state. FIG. 4 is a view when the MEMS tilt sensor is rotated 90 degrees counterclockwise from the reference state of FIG. FIG. 5 is a front view showing an example of the magnetic detection element in the present embodiment, and FIG. 6 is a view of the element part of FIG. 5 cut along the line BB and viewed from the arrow direction. FIG. 7 is an enlarged cross-sectional view, FIG. 7 is a schematic diagram showing a magnetization relationship between the first magnetic layer and the second magnetic layer constituting the magnetic detection element of FIG. 6, and FIG. 8A is a direction orthogonal to the sensitivity axis direction. Detection when an external magnetic field (disturbance magnetic field) acts from RH curve of the child, FIG. 8 (b), RH curve 9 of the magnetic detecting element when the external magnetic field is applied from the sensitivity axis direction, an electric circuit diagram of a MEMS tilt sensor is.

  The X1-X2 direction, the Y1-Y2 direction, and the Z1-Z2 direction in the figure are orthogonal to each other.

  FIG. 1 shows a form of the intermediate layer 15 that appears by deleting the cap substrate (first substrate) 2 shown in FIG. However, the magnetic detection elements 4 and 5 and the fixed resistance elements 6 and 7 arranged on the back surface 2a of the cap substrate 2 are illustrated.

  The MEMS tilt sensor 1 shown in FIGS. 1 and 2 includes a cap substrate (first substrate) 2, a support substrate (second substrate) 3, and an intermediate layer 15 positioned between the cap substrate 2 and the support substrate 3. The magnetic detection elements 4 and 5, the fixed resistance elements 6 and 7, and the magnet 8 are configured.

  The cap substrate 2, the support substrate 3, and the intermediate layer 15 are formed of, for example, a silicon substrate. As shown in FIG. 2, a recess 3 b is formed on the surface 3 a of the support substrate 3. In addition, a protruding sticking prevention portion 9 is formed in the recess 3b.

As shown in FIGS. 1 and 2, the intermediate layer 15 is separated into a frame body 10, a rotating weight 11, and a rotating shaft 12. As shown in FIGS. 1 and 2, the rotating weight 11 is formed in a substantially fan shape. A through hole 11b is formed on the distal end side (the side having a narrow width dimension in the X1-X2 direction) away from the circular arc portion 11a having a large curvature radius of the rotating weight 11. The pivot shaft 12 is inserted through the through hole 11b. The portion of the support substrate 3 that faces the rotating shaft 12 is in a protruding state. For example, the support substrate 3 and the rotating shaft 12 are fixed at room temperature via an oxide insulating layer (SiO ₂ ) 13. . Alternatively, the space between the support substrate 3 and the rotating shaft 12 may be fixed by eutectic bonding using a combination of aluminum and germanium.

  As shown in FIG. 2, the frame 10 and the support substrate 3 are also fixed in the same manner as described above. Although the oxide insulating layer 13 is formed on the back surface of the rotating weight 11, the oxide insulating layer 13 may not be formed. The mass of the rotating shaft 11 can be increased by forming the oxide insulating layer 13 on the back surface of the rotating weight 11.

  As shown in FIG. 2, a magnet 8 is installed on the surface 11 c of the rotating weight 11. In the reference state shown in FIG. 1, the magnet 8 has a bar shape elongated in the Z1-Z2 direction, and the X1 side is the S pole and the X2 side is the N pole. The center of the magnet 8 coincides with a center line C-C drawn parallel to the direction of gravity through the center of the rotating shaft 12. The magnet 8 may be provided on the back surface of the rotating weight 11, but when the magnet 8 and magnetic detection elements 4 and 5 described later face each other, an appropriate external magnetic field is applied from the magnet 8 to the magnetic detection elements 4 and 5. It is preferable to install the magnet 8 on the surface 11c of the rotating weight 11 so as to act.

  As shown in FIG. 2, the back surface 2 a of the cap substrate 2 is formed with a recess 2 b similarly to the front surface 3 a of the support substrate 3, and is provided with a protruding sticking prevention portion 14. The height dimension of the sticking prevention portion 14 must be formed at least larger than the film thickness of the magnetic detection elements 4 and 5 described later. In this embodiment, the shape of the back surface 2 a of the cap substrate 2 is a mirror pattern having the shape of the front surface 3 a of the support substrate 3. A large number of fine through holes 39 are formed in the cap substrate 2.

  As shown in FIG. 2, the cap substrate 2 in a portion facing the rotation shaft 12 and the frame body 10 has a protruding shape, and the space between the cap substrate 2 and the rotation shaft 12 and the frame body 10 is, for example, normal temperature bonding. Is fixed. As described above, fixation by eutectic bonding may be used.

  As shown in FIG. 2, the rotation shaft 12 is fixedly supported on the cap substrate 2 and the support substrate 3 from both sides.

  As shown in FIGS. 1 and 2, a minute clearance is provided between the through-hole 11 b formed in the rotating weight 11 and the rotating shaft 12. The shaft 12 is supported so as to be rotatable in the gravity direction (Z1 direction in FIG. 1) with the rotation center as a rotation center. When the MEMS tilt sensor 1 in this embodiment is rotated 90 degrees clockwise or counterclockwise from the reference state of FIG. 1 (see also FIGS. 3 and 4), the rotating weight 11 is in the direction of gravity ( The inner wall shape of the frame body 10 is determined so as to ensure 90 degrees of rotation from the reference state of FIG. The inner wall shape of the frame body 10 constitutes the rotation area 22 of the rotation weight 11.

  Further, as shown in FIG. 1, in the reference state of FIG. 1, the first magnetic detection element 4 and the second magnetism are arranged on both sides of a center line CC drawn through the center of the rotating shaft 12 and parallel to the direction of gravity. A detection element 5 is arranged. In this embodiment, the first magnetic detection element 4 and the second magnetic detection element 5 are just in a positional relationship aligned with the rotation shaft 12 in the X1-X2 direction. These magnetic detection elements 4 and 5 face the magnet 8 when the MEMS tilt sensor 1 is rotated 90 degrees clockwise or counterclockwise from the reference state shown in FIG. 1 (see also FIGS. 3 and 4). It is provided in the position to do.

  The first magnetic detection element 4 and the second magnetic detection element 5 are provided on the back surface 2a of the cap substrate 2 as shown in FIG. Hereinafter, the configuration of the magnetic detection elements 4 and 5 will be described.

  The first magnetic detection element 4 and the second magnetic detection element 5 are elements extending in the Z1-Z2 direction as shown in FIG. 5 (enlarged front view of the magneto-magnetic detection element in the same reference state as FIG. 1). The unit 19 is provided. The element width in the X1-X2 direction of the element part 19 is formed by W1, and the length dimension in the Z1-Z2 direction of the element part 19 is formed by L1. As shown in FIG. 5, the length dimension L1 is larger than the element width W1. Therefore, the element portion 19 is formed in an elongated shape with the Z1-Z2 direction as the longitudinal direction.

  As shown in FIG. 5, a plurality of element portions 19 are provided, and each element portion 19 is arranged in parallel at a predetermined interval T1 in the X1-X2 direction.

  As shown in FIG. 5, the end portions of each element portion 19 in the Z1-Z2 direction are connected by a connecting portion 20. The connection portion 20 is formed of an electrode layer made of a nonmagnetic conductive material, or is formed of a hard bias layer or the like. The magnetic detection elements 4 and 5 are formed in a meander shape by the element part 19 and the connection part 20. As shown in FIG. 1, the connecting portion 20 may be formed in the same layer configuration as the element portion 19 and may have a meander shape integrated with the layer configuration of the element portion 19. However, in such a case, since the position of the connecting portion 20 also becomes a sensitivity region for detecting an external magnetic field, in order to weaken the sensitivity at the position of the connecting portion 20, it is desirable to form it in a curved shape as shown in FIG. .

  The element part 19 is formed in the multilayer structure shown in FIG. As shown in FIG. 6, the element portion 19 is laminated in order of the seed layer 30, the first magnetic layer 31, the nonmagnetic layer 32, the second magnetic layer 33, and the protective layer 34 from the back surface 2 a side of the cap substrate 2. The seed layer 30 is formed of NiFeCr or Cr. The seed layer 30 is a layer provided for adjusting the crystal orientation of each layer. The seed layer 30 may not be formed. Further, a nonmagnetic underlayer made of Ta or the like may be formed between the seed layer 30 and the cap substrate 2.

The first magnetic layer 31 is laminated in the order of the Ni—Fe layer 35 and the Co—Fe layer 36.
The nonmagnetic layer 32 is preferably formed of one or more alloys of Cu, Ru, Rh, Ir, Cr, and Re.

The second magnetic layer 33 is laminated in the order of the Co—Fe layer 37 and the Ni—Fe layer 38.
The protective layer 34 is made of Ta, for example. The formation of the protective layer 34 is not essential, but it is better to form it.

  As shown in FIG. 6, the first magnetic layer 31 and the second magnetic layer 33 are laminated via the nonmagnetic layer 32. Both the first magnetic layer 31 and the second magnetic layer 33 have a laminated structure of Co—Fe layers 36 and 37 and Ni—Fe layers 35 and 38. As shown in FIG. 6, the Co—Fe layer 36 constituting the first magnetic layer 31 and the Co—Fe layer 37 constituting the second magnetic layer 33 are opposed to each other with the nonmagnetic layer 32 interposed therebetween.

  Both the first magnetic layer 31 and the second magnetic layer 33 are preferably formed of the same magnetic material. Thereby, it is easy to adjust Ms · t (Ms is saturation magnetization and t is film thickness) of the first magnetic layer 31 and the second magnetic layer 33.

  The first magnetic layer 31 and the second magnetic layer 33 may be formed of a magnetic material other than Ni—Fe or Co—Fe. Further, each of the magnetic layers 31 and 33 may have a single layer structure or a laminated structure.

  However, as shown in FIG. 6, each of the magnetic layers 31, 33 is formed by a stacked structure of Ni—Fe layers 35, 38 and Co—Fe layers 36, 37, and the Co—Fe layers 36, 37 are interposed via the nonmagnetic layer 32. Are preferably opposed to each other. Thereby, it is possible to prevent NiFe from diffusing into the nonmagnetic layer 32 when heat is applied.

  Both the first magnetic layer 31 and the second magnetic layer 33 can change the magnetization with respect to an external magnetic field. That is, the magnetization is not fixed like the pinned magnetic layer of the GMR element.

  In the present embodiment, the longitudinal direction of the element portion 19 (Z1-Z2 direction in the reference state of FIGS. 1, 5, and 6) is the sensitivity axis direction.

  As shown in FIG. 7, in the non-magnetic state (the state in which no external magnetic field is applied), the magnetization direction F1 of the first magnetic layer 31 is the first of the sensitivity axis directions from the reference direction orthogonal to the sensitivity axis direction. The magnetization direction F2 of the second magnetic layer 33 is inclined from the reference direction to a second direction opposite to the first direction in the sensitivity axis direction. At this time, the angle θ1 between the magnetization direction F1 of the first magnetic layer 31 and the reference direction and the angle θ2 between the magnetization direction F2 of the second magnetic layer 33 and the reference direction are substantially the same angle. The angle θ3 between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 is in the range of 90 degrees to 180 degrees.

  As shown in FIG. 6, in the present embodiment, in the non-magnetic state, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 are substantially anti-parallel toward the sensitivity axis direction. It is preferable that

  Here, “substantially antiparallel” means that the angle θ3 (obtuse angle) between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 is within a range of 150 degrees to 180 degrees.

  A coupling magnetic field is generated between the first magnetic layer 31 and the second magnetic layer 33 by the RKKY interaction.

  FIG. 8A shows a resistance change when an external magnetic field is applied to the magnetic detection element having the laminated structure of FIG. 6 from the direction orthogonal to the sensitivity axis direction, and FIG. The resistance change when an external magnetic field is made to act on a magnetic detection element having a laminated structure from the sensitivity axis direction is shown. FIG. 8 shows the resistance change within the range of −50 Oe to +50 Oe.

  The experiment was performed using one element portion 19 having an element width W1 of 3 μm (an aspect ratio (L1 / W1) of 100). In addition, the angle θ3 (obtuse angle) between the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 in the absence of a magnetic field (external magnetic field is 0 Oe) was about 180 degrees.

  As shown in FIG. 8A, the resistance value does not change much with respect to an external magnetic field (disturbance magnetic field) from a direction different from the sensitivity axis direction.

  On the other hand, as shown in FIG. 8B, when the external magnetic field is increased in the sensitivity axis direction from the non-magnetic state (external magnetic field is 0 Oe), the first magnetic field is generated by the external magnetic field and the coupling magnetic field due to the RKKY interaction. The magnetization direction F1 of the layer 31 and the magnetization direction F2 of the second magnetic layer 33 are antiparallel, and the resistance value reaches the maximum value. When the external magnetic field in the sensitivity axis direction is further increased, the antiparallel state is lost, the magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 approach a parallel state, and the resistance value is increased. Decrease gradually.

  As shown in FIG. 8B, substantially the same RH is applied to both external magnetic fields in the first direction (for example, the positive value direction) and the second direction (for example, the negative value direction) in the sensitivity axis direction. It has characteristics.

  As shown in FIG. 1, the first magnetic detection element 4 and the second magnetic detection element 5 are provided in a region where the cap substrate 2 faces the rotation region 22 of the rotation weight 11. At this time, the magnetic detection elements 4 and 5 may be provided on the surface of the cap substrate 2. In this case, the distance between the magnetic detection elements 4 and 5 and the magnet 8 is increased so that the magnetic detection elements are separated from the magnet 8. The external magnetic field acting on the magnetic detection elements 4 and 5 is weakened, and it is necessary to newly provide a lid on the surface side of the magnetic detection elements 4 and 5. Therefore, the magnetic detection elements 4 and 5 are preferably provided on the back surface 2 a of the cap substrate 2.

  As shown in FIG. 1, the fixed resistance elements 6 and 7 are provided outside the facing region of the cap substrate 2. The fixed resistance elements 6 and 7 are formed with the same element configuration as the first magnetic detection element 4 and the second magnetic detection element 5 (see FIGS. 5 and 6). However, the fixed resistance elements 6 and 7 are provided outside the facing region of the cap substrate 2 as described above, and the magnet 8 and the fixed resistance element 6 can be operated even when the MEMS tilt sensor 1 described below is rotated. , 7 do not face each other, and does not receive an external magnetic field from the magnet 8. Therefore, even if the fixed resistance elements 6 and 7 are formed with the same element configuration as the magnetic detection elements 4 and 5, it is possible to substantially eliminate the electrical resistance change accompanying the rotation operation of the magnet 8. The magnetic detection elements 4 and 5 and the fixed resistance elements 6 and 7 constitute a bridge circuit shown in FIG.

Next, the principle of rotation detection by the MEMS tilt sensor 1 of this embodiment will be described.
From the reference state of FIG. 1, the MEMS tilt sensor 1 is rotated 90 degrees clockwise as shown in FIG. Then, the rotating weight 11 rotates about the rotating shaft 12 and maintains a constant posture in the direction of gravity.

  Since the magnetic detection elements 4 and 5 are fixed to the cap substrate 2, when the MEMS tilt sensor 1 is rotated 90 degrees clockwise from the reference state, the magnetic detection elements 4 and 5 are also 90 degrees clockwise from the reference state. Rotate. Therefore, as shown in FIG. 3, the rotating weight 11 that always maintains the posture directed in the direction of gravity and the second magnetic detection element 5 rotated 90 degrees in the clockwise direction from the reference state face each other. At this time, since the magnetization direction of the magnet 8 coincides with the longitudinal direction (sensitivity axis direction) of the element portion 19 (see also FIG. 5) constituting the second magnetic detection element 5, the sensitivity of the second magnetic detection element 5 is increased. An external magnetic field acts from the magnet 8 in the axial direction, and the electrical resistance value of the second magnetic detection element 5 decreases due to the RH characteristics described with reference to FIG.

  On the other hand, in the rotation state of FIG. 3, not only the fixed resistance elements 6 and 7 functioning as fixed resistance elements, but also the first magnetic detection element 4 on the side away from the magnet 8 does not receive an external magnetic field, so that the electric resistance value changes. do not do. Therefore, the differential output based on the electrical resistance change of the second magnetic detection element 5 is obtained from the bridge circuit of FIG. 9, and the MEMS tilt sensor 1 is rotated 90 degrees clockwise based on the differential output. Can be detected.

  Subsequently, when the MEMS tilt sensor 1 is rotated 90 degrees counterclockwise from the reference state, the magnetic detection elements 4 and 5 are also rotated 90 degrees counterclockwise from the reference state. Therefore, as shown in FIG. 4, the rotating weight 11 that always maintains the posture directed in the direction of gravity and the first magnetic detection element 4 rotated 90 degrees counterclockwise from the reference state are opposed to each other. At this time, since the magnetization direction of the magnet 8 coincides with the longitudinal direction (sensitivity axis direction) of the element portion 19 (see also FIG. 5) constituting the first magnetic detection element 4, the sensitivity of the first magnetic detection element 4. An external magnetic field acts from the magnet 8 in the axial direction, and the electric resistance value of the first magnetic detection element 4 decreases as described with reference to FIG.

  On the other hand, in the rotation state of FIG. 4, not only the fixed resistance elements 6 and 7 that function as fixed resistance elements, but also the second magnetic detection element 5 on the side away from the magnet 8 does not receive an external magnetic field, so that the electric resistance value changes. do not do. Therefore, a differential output based on the change in the electric resistance of the first magnetic detection element 4 is obtained from the bridge circuit of FIG. 9, and the MEMS tilt sensor 1 rotates 90 degrees counterclockwise based on this differential output. Can be detected.

  In this embodiment, as shown in FIGS. 1 and 2, the MEMS tilt sensor 1 is formed using the MEMS technology, so that the tilt sensor can be reduced in size as compared with the prior art, and the manufacturing cost is reduced. It is possible.

  In the present embodiment, the magnetic detection elements 4 and 5 having the configurations and characteristics shown in FIGS. 5 to 8 are used. That is, as shown in FIG. 6, the first magnetic layer 31 and the second magnetic layer 33 that can change the magnetization with respect to an external magnetic field are provided with the element portion 19 facing each other with the nonmagnetic layer 32 interposed therebetween. The magnetization direction F1 of the first magnetic layer 31 and the magnetization direction F2 of the second magnetic layer 33 have the relationship shown in FIG. 7, and the element portion 19 is formed in an elongated shape with the sensitivity axis direction as the longitudinal direction. For this reason, as shown in FIG. 8, the electric resistance greatly fluctuates with respect to the external magnetic field from the sensitivity axis direction, while the resistance changes greatly with respect to the external magnetic field (disturbance magnetic field) from a direction different from the sensitivity axis direction. RH characteristics not to be provided.

  3 and 4, when the magnet 8 and the magnetic detection elements 4 and 5 face each other, the magnetization direction of the magnet 8 and the longitudinal direction of the element portion 19 constituting the magnetic detection elements 4 and 5 ( The arrangement of the magnet 8 and the magnetic detection elements 4 and 5 in the reference state shown in FIG.

  As a result, as shown in FIGS. 3 and 4, when the magnet 8 and the magnetic detection elements 4 and 5 are substantially opposed to each other, an external magnetic field from the sensitivity axis direction acts on the magnetic detection elements 4 and 5. As shown in FIG. 8B, the electrical resistance value decreases, and the MEMS tilt sensor 1 is detected to be rotated approximately 90 degrees clockwise or counterclockwise by the differential output from the electrical circuit of FIG. Is possible.

  By using the magnetic detection elements 4 and 5 having the configurations and characteristics shown in FIGS. 5 to 8, even if an external magnetic field acts from a direction different from the sensitivity axis direction as shown in FIG. , 5 does not change much. Therefore, disturbance magnetic field tolerance can be improved and malfunction can be suppressed. In addition, even when an external magnetic field acts on the magnetic detection elements 4 and 5 from the magnet 8 in the middle of the rotation of the MEMS tilt sensor 1 from the reference state of FIG. Since the direction of the external magnetic field is different from the direction of the sensitivity axis, the change in resistance value is small and the rotation is not detected. As shown in FIGS. 3 and 4, the magnetic detection elements 4 and 5 and the magnet 8 is in a substantially opposite state, a large electric resistance change occurs, and the rotation state can be detected. That is, since rotation detection is determined when the magnetic detection elements 4 and 5 and the magnet 8 are substantially opposed to each other, it is possible to improve rotation detection accuracy. Further, in the magnetic detection elements 4 and 5 having the configurations and characteristics shown in FIGS. 5 to 8, as shown in FIG. 8B, the external magnetic field from the sensitivity axis direction is the first direction (for example, a positive value). Even in the second direction (for example, a negative value), the same electric resistance change is exhibited. Therefore, if the magnetic detection elements 4 and 5 having the configurations and characteristics shown in FIGS. 5 to 8 are used, substantially the same output characteristics can be obtained even in the magnetization direction opposite to the magnetization direction of the magnet 8 shown in FIG. I can do it. In other words, since it is not necessary to consider the magnetization direction of the magnet 8, the installation process of the magnet 8 can be facilitated.

  In the present embodiment, as the magnetic detection elements 4 and 5, in addition to the elements having the configurations and characteristics shown in FIGS. 5 to 8, a magnetoresistive effect element (MR element) using the magnetoresistive effect (MR effect), It may be a Hall element or the like.

  However, when an MR element is used, the electric resistance value changes due to the action of an external magnetic field from the film surface direction, so that the magnetic detection elements 4 and 5 and the magnet 8 are substantially opposed to each other as shown in FIGS. However, if an external magnetic field from the magnet 8 acts on the magnetic detection elements 4 and 5, the electric resistance values of the magnetic detection elements 4 and 5 are likely to fluctuate. It is considered that the magnetic detection elements 4 and 5 having the configuration and characteristics of FIG. 8 are superior. In addition, the magnetic detection element 4 uses a configuration of an MR element that changes its electrical resistance value when a positive external magnetic field acts, and does not change its electric resistance value when a negative external magnetic field acts. As the element 5, an MR element configuration having an RH characteristic opposite to that of the magnetic detection element 4 can be used. However, in such a case, the magnetic detection element 4 and the magnetic detection element 5 must be formed separately, which increases the number of processes. Moreover, since the magnetizing direction of the magnet 8 cannot be reversed and determined in a certain direction, the installation process of the magnet 8 cannot be facilitated.

  Further, when the Hall element is used, the thickness of the magnet 8 must be increased so that an external magnetic field from the direction perpendicular to the film surface can be appropriately applied to the Hall element, and the thinning of the MEMS tilt sensor 1 cannot be promoted. There's a problem.

  As described above, it is preferable to use the magnetic detection elements 4 and 5 having the configurations and characteristics shown in FIGS. 5 to 8 in the MEMS tilt sensor 1 having the structure shown in FIG.

  In the present embodiment, the fixed resistance elements 6 and 7 are formed in the same element configuration as the magnetic detection elements 4 and 5. Therefore, since the magnetic detection elements 4 and 5 and the fixed resistance elements 6 and 7 can be simultaneously formed on the back surface 2a of the cap substrate 2, the manufacturing efficiency can be improved and the manufacturing cost can be reduced more effectively. I can do it. Also, even if the disturbance magnetic field acts and the electric resistance value changes, all the magnetic detection elements 4 and 5 and the fixed resistance elements 6 and 7 show the same electric resistance change, so the output fluctuation is small and malfunctions occur. It is possible to make the configuration difficult to occur.

  Next, the manufacturing method of the MEMS inclination sensor 1 of FIG. 1 is demonstrated using FIG. Each drawing of FIG. 10 is a cross-sectional view of the MEMS tilt sensor 1 during the manufacturing process.

  In the step of FIG. 10A, the recess 3b and the sticking prevention portion 9 are formed on the surface 3a of the support substrate 3 made of a silicon substrate. Further, when the oxide insulating layer (sacrificial layer) in FIG. 10E is removed, a thin oxide insulating layer may be formed to protect the surface 3a of the support substrate 3.

Next, in the step of FIG. 10B, an intermediate layer 15 made of a silicon substrate is prepared. An oxide insulating layer (SiO ₂ ) 13 is formed on the entire back surface of the intermediate layer 15. Further, the magnet 8 shown in FIG. 1 is installed on the surface of the intermediate layer 15. Then, the support substrate 3 and the intermediate layer 15 are fixed by, for example, room temperature bonding through the oxide insulating layer 13.

  Next, in the process of FIG. 10C, the intermediate layer 15 is etched to pattern the frame body 10, the rotating weight 11, and the rotating shaft 12.

  Next, in the step of FIG. 10D, the cap substrate 2 in which the concave portion 2b and the sticking prevention portion 14 are formed on the back surface 2a and the magnetic detection elements 4 and 5 and the fixed resistance elements 6 and 7 are installed. It fixes to the frame 10 and the rotating shaft 12 of the intermediate | middle layer 15 by normal temperature joining, for example. Further, as shown in FIG. 10 (d), fine through holes 39 are formed in the cap substrate 2.

  10E, the other oxide insulating layer 13 is removed while leaving the oxide insulating layer 13 between the rotating shaft 12 and the support substrate 3 and the oxide insulating layer 13 between the frame 10 and the support substrate 3. As described above, the oxide insulating layer 13 is removed by etching with an etching gas or an etchant passing through the through holes 39. At this time, as shown in FIG. 10E, a part of the oxide insulating layer 13 is also left on the back surface of the rotating weight 11.

  The MEMS tilt sensor 1 can be mounted on a mobile phone, a game machine, a digital camera, a video camera, an automobile, a motorcycle, or the like, but the application is not particularly limited.

  Further, in the configuration of the MEMS tilt sensor 1 of FIG. 1, as shown in FIGS. 3 and 4, the MEMS tilt sensor 1 is rotated by 90 degrees clockwise or counterclockwise from the reference state of FIG. Although the configuration can detect the state, the detected rotation angle can be arbitrarily set according to the installation position of the magnetic detection elements 4 and 5. At this time, when the magnetic detection elements 4 and 5 having the configurations and characteristics shown in FIGS. 5 to 8 are used, the magnetic detection elements 4 and 5 and the magnet 8 are opposed to each other when the rotation detection angle is reached. Adjust the installation position and orientation of the magnetic detection elements 4 and 5 according to the rotation detection angle so that the magnetization direction and the longitudinal direction (sensitivity axis direction) of the element portion 19 of the magnetic detection elements 4 and 5 coincide. is required.

  In FIG. 1, the magnetic detection elements 4 and 5 are installed one by one on both sides of the center line CC, but the number of magnetic detection elements 4 and 5 can be arbitrarily determined. For example, when the rotation detection angles are 30 degrees, 60 degrees, and 90 degrees, three magnetic detection elements 4 and 5 may be set on each of the left and right sides according to the rotation detection angles.

The perspective front view of the MEMS inclination sensor in this embodiment, Sectional drawing of the MEMS inclination sensor cut | disconnected from the AA line shown in FIG. FIG. 3 is a perspective front view of the MEMS tilt sensor when the MEMS tilt sensor is rotated 90 degrees clockwise from the reference state of FIG. FIG. 3 is a perspective front view of the MEMS tilt sensor when the MEMS tilt sensor is rotated 90 degrees counterclockwise from the reference state of FIG. 1; The front view which shows an example of the magnetic detection element in this embodiment, FIG. 5 is a partially enlarged cross-sectional view of the element portion of FIG. 5 cut along the line BB and seen from the arrow direction; FIG. 7 is a schematic diagram showing a magnetization relationship between a first magnetic layer and a second magnetic layer constituting the magnetic detection element of FIG. FIG. 8A shows an RH curve of the magnetic detection element when an external magnetic field (disturbance magnetic field) acts from a direction orthogonal to the sensitivity axis direction, and FIG. 8B shows an external magnetic field acting from the sensitivity axis direction. RH curve of the magnetic detection element when Electrical circuit diagram of MEMS tilt sensor, Process drawing (sectional drawing) which shows the manufacturing method of the MEMS inclination sensor of this embodiment,

DESCRIPTION OF SYMBOLS 1 MEMS inclination sensor 2 Cap board | substrate 3 Support board | substrate 4, 5 Magnetic detection element 6, 7 Fixed resistance element 8 Magnet 9, 14 Sticking prevention part 11 Rotating weight 12 Rotating shaft 13 Oxide insulating layer 15 Intermediate layer 19 Element part 22 Rotating region 31 First magnetic layer 32 Nonmagnetic layer 33 Second magnetic layer

Claims (4)

In a MEMS inclination sensor comprising a magnet and a magnetic detection element that is arranged in a non-contact manner with the magnet and changes its electrical characteristics in response to an external magnetic field from the magnet.
A first substrate, a second substrate, and an intermediate layer located between the first substrate and the second substrate;
The intermediate layer includes a rotating weight, and a rotating shaft that is inserted into a through-hole formed in the rotating weight and is fixedly supported by the first substrate and the second substrate. Is supported so that it can rotate in the direction of gravity,
The magnet is installed on the rotating weight, and the magnetic detection element is installed in a region facing the first substrate with respect to the rotating area of the rotating weight,
In the reference state of the MEMS tilt sensor, the magnetic detection elements are disposed on both sides of a center line drawn in parallel to the direction of gravity through the center of the rotation shaft,
When the MEMS tilt sensor is rotated clockwise or counterclockwise from the reference state, the rotating weight rotates and maintains a constant posture in the gravity direction, while the magnetic detection element is rotated clockwise or counterclockwise. The magnetic detection element that rotates in the direction and approaches the magnet at this time receives an external magnetic field from the magnet, and changes its electrical characteristics, and the rotation state can be known based on the change in electrical characteristics. MEMS tilt sensor.   The fixed resistance element which comprises the said magnetic detection element and an electric circuit is provided outside the said opposing area | region of the said 1st board | substrate, The said fixed resistance element is the same element structure as the said magnetic detection element. MEMS tilt sensor. The magnetic detection element includes an element portion whose electric resistance value changes with respect to an external magnetic field from the sensitivity axis direction,
The element portion has a laminated structure in which a first magnetic layer and a second magnetic layer are laminated via a nonmagnetic layer,
Both the first magnetic layer and the second magnetic layer can change magnetization with respect to the external magnetic field,
In the absence of a magnetic field, the magnetization direction of the first magnetic layer is inclined from the reference direction orthogonal to the sensitivity axis direction to the first direction of the sensitivity axis direction, and the magnetization direction of the second magnetic layer is The second magnetic layer is inclined from the reference direction in a second direction opposite to the first direction in the sensitivity axis direction, the angle between the magnetization direction of the first magnetic layer and the reference direction, and the second magnetic layer And the reference direction are substantially the same angle, and the angle between the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer is in the range of 90 degrees to 180 degrees. Within
The element portion is formed in an elongated shape having the sensitivity axis direction as a longitudinal direction, and the magnet and the magnetic detection element are opposed to each other by rotating the MEMS tilt sensor clockwise or counterclockwise from a reference state. The MEMS inclination sensor according to claim 1 or 2, wherein the arrangement of the magnet and the element portion is regulated so that the magnetizing direction of the magnet coincides with the longitudinal direction of the element portion.   4. The MEMS tilt sensor according to claim 3, wherein the magnetization direction of the first magnetic layer and the magnetization direction of the second magnetic layer are substantially antiparallel toward a direction parallel to the sensitivity axis direction.

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