JP2012127692A - Mems sensor and manufacturing method of the same, and mems package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MEMS sensor and a manufacturing method of the MEMS sensor that can reduce the variation in size of comb-shaped first electrodes and second electrodes that engage with each other and can improve the detection accuracy of the sensor.SOLUTION: By etching a base substrate 7, a columnar part 29 and a base part 30 are formed. Then, the columnar part 29 and the base part 30 are transformed into an insulating film by thermal oxidation. Thus, an insulating layer 85 made of the columnar part 29 as well as a base insulating layer 21 made of the surface portion of the base part 30 are formed. Then, a polysilicon layer 22 is formed on the base insulating layer 21, and a laminated structure of the polysilicon layer 22 and the base insulating layer 21 are etched to be formed into shapes of Z-fixed electrodes 71 and Z-movable electrodes 72, while trenches 50 are concurrently formed between them. Finally, by conducting an isotropic etching on the bottoms of the trenches 50, a recess 20 (cavity 23) is formed directly below the base insulating layer 21.

Description

  The present invention relates to a manufacturing method of a MEMS sensor, a MEMS sensor manufactured by the manufacturing method, and a MEMS package including the MEMS sensor.

The capacitive acceleration sensor detects acceleration by detecting the amount of change in capacitance between the electrodes facing each other (between the fixed electrode and the movable electrode).
The acceleration sensor (100) disclosed in FIGS. 1a to 1g of Patent Document 1 includes, for example, two layers of an Si electrode (112) and a metal electrode (122) that are sequentially stacked via an insulating layer (132). The fixed portion (400) and the Si electrode (116) having the same shape as the Si electrode (112) of the fixed portion (400) and completely facing the Si electrode (112) in the reference posture (FIG. 1d of Patent Document 1) The movable part (300) which consists of a single layer. The acceleration sensor (100) measures the amount of change in capacitance between the Si electrode (116) of the movable part (300) that vibrates up and down by the action of acceleration and the Si electrode (112) of the fixed part (400). By detecting this, the acceleration in the Z-axis direction is detected.

U.S. Pat. No. 6,792,804

In the invention of Patent Document 1, the plurality of Si electrodes (116) forming the movable part (300) are formed by forming a plurality of trenches in the Si substrate and continuing the lower portions of the trenches to each other by isotropic etching. It is formed (FIGS. 6a to 6g of Patent Document 1).
However, both the material to be left as the Si electrode (116) and the material to be removed by etching are both Si. Therefore, when forming the cavity (640), the lower part of the Si electrode (116) is eroded by the etching medium (FIG. 6g of Patent Document 1). As a result, the size variation of the plurality of Si electrodes (116) forming the movable part (300) is large, and the movable part (300) may not vibrate as designed.

Accordingly, an object of the present invention is to provide a MEMS sensor that can reduce variations in the sizes of the comb-shaped first electrode and the second electrode that mesh with each other, and that can improve the detection accuracy of the sensor, and a method for manufacturing the same. It is.
Another object of the present invention is to provide a MEMS package including a MEMS sensor having excellent detection accuracy.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a step of forming a base film made of a material having an etching selectivity with respect to Si on a Si substrate, and a polysilicon layer on the base film. Forming a trench from the surface of the polysilicon layer to the surface of the Si substrate by selectively etching the polysilicon layer and the base film, and simultaneously forming the base film and the polysilicon Forming a comb-shaped first electrode and a second electrode having a laminated structure with each other and meshing with each other across the trench, and isotropic etching for supplying an etching medium to the trench, the Si substrate And a step of etching a portion immediately below the base film to form a cavity immediately below the base film.

  According to this method, the lowermost layer of the first electrode and the second electrode is made of the base film having an etching selectivity with respect to Si. Therefore, when the cavity is formed by isotropic etching of the Si substrate, even if the etching medium contacts the first electrode and the second electrode, erosion of the first electrode and the second electrode can be reduced. As a result, a MEMS sensor having a first electrode and a second electrode with little variation in size can be manufactured.

Such a MEMS sensor is, for example, as described in claim 6, a Si substrate having a surface layer portion in which a recess is formed, and a layer disposed in order from the side close to the recess, which is disposed immediately above the recess of the Si substrate. The first electrode and the second electrode have a laminated structure of a base film made of an insulating material and a polysilicon layer and are engaged with each other with a gap therebetween.
According to this configuration, there is little variation in the sizes of the comb-shaped first electrode and the second electrode meshing with each other, so that the detection accuracy of the sensor can be improved.

The material having an etching selectivity with respect to Si (in this paragraph, defined as material A) is, for example, the etching rate of Si with respect to a certain etching medium and the etching rate of material A with respect to the etching medium. (Etching selectivity) = (material A etching rate / Si etching rate) ≠ 1. In particular, the material A is preferably a material that can make the etching selectivity close to zero (etching selection ratio≈0). Specifically, the material A is SiO ₂ as described in claim 13. Is preferred.

  According to a second aspect of the present invention, in the step of forming the base film, the Si substrate is made to stand on the plate-like base portion and the surface of the base portion by selectively etching the Si substrate. A step of processing into a provided columnar portion, and a step of thermally oxidizing the surface of the base portion and the columnar portion to transform the surface of the base portion and the columnar portion into an insulating film, The step of selectively etching the polysilicon layer and the base film is performed by the first electrode and / or the second electrode from the other part of the polysilicon layer due to the columnar portion transformed into the insulating film, respectively. It is a manufacturing method of the MEMS sensor of Claim 1 including the process of etching so that it may be insulated.

  The MEMS sensor according to claim 7, that is, embedded in the first electrode so as to penetrate the polysilicon layer and reach the base film by this method, and a portion of the first electrode is selectively The MEMS sensor according to claim 6, further comprising a first insulating layer that insulates from other parts of the polysilicon layer. The MEMS sensor according to claim 8, that is, embedded in the second electrode so as to penetrate the polysilicon layer and reach the base film, and a portion of the second electrode is selectively formed in the polysilicon. The MEMS sensor according to claim 6 or 7, further comprising a first insulating layer that insulates from other parts of the layer.

By the way, in invention of patent document 1, the several part which should be electrically insulated in Si substrate is isolate | separated by the isolation | separation joint (Isolation joint 160,360 ...). As shown in FIG. 6a of Patent Document 1, the separation joint is formed by forming a trench in a Si substrate and thermally oxidizing the inner walls (side walls and bottom wall) of the trench. When the inner wall of the trench is thermally oxidized, SiO ₂ is grown from the side and bottom walls towards the inside of the trench, SiO ₂ with each other to any integrated grown from each wall. By this integration, a separation joint embedded in the trench (612 in FIG. 6a) is obtained. However, since the isolation joint obtained in this way is a film formed by growing a plurality of SiO ₂ inside the trench that was originally empty and integrating them, its strength is not so high, It takes time to form.

  Therefore, in the invention according to claim 2, the shapes of the first insulating layer according to claim 7 and the second insulating layer according to claim 8 are formed as columnar portions by etching a Si substrate having a well-structured crystal structure. Next, the columnar portion is thermally oxidized to be transformed into an insulating film. Next, a polysilicon layer is formed around the insulating film, and the polysilicon layer is etched into the shape of the first electrode and the second electrode. That is, in the invention according to claim 2, since the shape of the first insulating layer and the second insulating layer is formed by etching of Si, the strength is high in a short time compared with the method for forming the separation joint of Patent Document 1. Can be formed as an insulating layer.

  According to a third aspect of the present invention, the step of forming the polysilicon layer includes depositing a polysilicon material on the base portion up to a position higher than the top of the columnar portion, and the deposited polysilicon. And a step of grinding the polysilicon material until a surface of the silicon material reaches a height position of the top of the columnar part.

By this method, a polysilicon layer having the same thickness as the height of the insulating film made of the columnar portion can be formed. Therefore, a certain part of the first electrode and the second electrode can be reliably insulated from the other part of the polysilicon layer.
The invention according to claim 4 further includes a step of forming a protective film having an etching selectivity with respect to polysilicon so as to cover the side walls of the first electrode and the second electrode. 4. The method for manufacturing the MEMS sensor according to claim 3.

  According to this method, the side walls of the first electrode and the second electrode are covered with the protective film having an etching selectivity with respect to Si. Therefore, when the cavity is formed by isotropic etching of the Si substrate, even if the etching medium contacts the side walls of the first electrode and the second electrode, erosion of the first electrode and the second electrode can be reduced. . As a result, variation in the size of the first electrode and the second electrode can be further reduced.

The invention according to claim 5 includes a step of selectively forming wiring on the polysilicon layer prior to the formation of the trench. It is a manufacturing method.
According to this method, since the wiring is formed on the polysilicon layer before being formed into the complicated comb-teeth first electrode and second electrode, the wiring for contacting the first electrode and the second electrode is formed. It can be easily formed.

In the MEMS sensor described above, the first electrode and the second electrode may be configured such that the first electrode is a movable electrode and the second electrode is a fixed electrode. The first electrode may be a fixed electrode, and the second electrode may be a movable electrode.
Moreover, the MEMS sensor mentioned above detects the acceleration which acted on the said MEMS sensor by detecting the change of the electrostatic capacitance between the said 1st electrode and the said 2nd electrode as described in Claim 11. An acceleration sensor may be included.

In this configuration, acceleration can be detected by a capacitor composed of the first electrode and the second electrode with little variation in size. Therefore, the acceleration acting on the sensor can be detected with high accuracy.
Further, as described in claim 12, the MEMS sensor described above drives the first electrode in a direction toward and away from the concave portion, and an angular velocity acting on the MEMS sensor at the time of driving is set to the first electrode. An angular velocity sensor that detects a change in capacitance with the second electrode may be included.

In this configuration, since the variation in the size of the first electrode is small, the first electrode can be driven as designed. Therefore, it is possible to accurately detect the angular velocity acting on the sensor.
The base film may have a thickness of 2 μm to 10 μm. The thickness of the polysilicon layer may be 5 μm to 20 μm.

The invention according to claim 16 is a MEMS package including the MEMS sensor according to any one of claims 6 to 15 and a resin package formed so as to cover the MEMS sensor.
According to this configuration, the MEMS sensor of the present invention is used. Therefore, in the MEMS sensor, variation in the sizes of the comb-shaped first electrode and the second electrode that mesh with each other can be reduced, so that the detection accuracy of the sensor can be improved. As a result, a MEMS package including a MEMS sensor having excellent detection accuracy can be provided.

  In addition, the MEMS package described above may further include an integrated circuit electrically connected to the MEMS sensor and covered with the same resin package together with the MEMS sensor. Moreover, when the substrate further includes a substrate having a front surface and a back surface and supporting the MEMS sensor on the front surface, the resin package covers the surface of the substrate and the substrate. The MEMS sensor may be sealed so as to expose the back surface.

It is a typical perspective view of the MEMS package which concerns on one Embodiment of this invention. FIG. 2 is a schematic plan view of the angular velocity sensor shown in FIG. 1. It is a principal part top view of the X-axis sensor shown in FIG. It is principal part sectional drawing of the X-axis sensor shown in FIG. 2, Comprising: The cross section in the cut surface AA of FIG. 3 is shown. It is a principal part top view of the Z-axis sensor shown in FIG. It is principal part sectional drawing of the Z-axis sensor shown in FIG. 2, Comprising: The cross section in the cut surface BB of FIG. 5 is shown. FIG. 7 is a cross-sectional view showing a part of the manufacturing process of the Z-axis sensor shown in FIG. It is a figure which shows the next process of FIG. 7A. It is a figure which shows the next process of FIG. 7B. It is a figure which shows the next process of FIG. 7C. It is a figure which shows the next process of FIG. 7D. It is a figure which shows the next process of FIG. 7E. It is a figure which shows the next process of FIG. 7F. It is a figure which shows the next process of FIG. 7G. It is a figure which shows the next process of FIG. 7H. FIG. 7B is a diagram showing a step subsequent to that in FIG. 7I. It is a figure which shows the next process of FIG. 7J. It is a top view which shows the form in the case of utilizing the Z-axis sensor shown in FIG. 5 for an acceleration sensor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<Overall configuration of MEMS package>
FIG. 1 is a schematic perspective view of a MEMS package according to an embodiment of the present invention.
The MEMS package 1 is used for applications such as camera shake correction for video cameras and still cameras, car navigation position detection, and motion detection for robots and game machines, for example.

The MEMS package 1 includes a substrate 2, an angular velocity sensor 3 as a MEMS sensor, an external terminal 4, an integrated circuit 5 (ASIC: Application Specific Integrated Circuit), and a resin package 6.
The substrate 2 is formed in a rectangular plate shape having a front surface and a back surface.
The angular velocity sensor 3 is disposed at one end in the longitudinal direction on the surface side of the substrate 2. The angular velocity sensor 3 is disposed on a side of the base substrate 7 made of a square plate-shaped Si substrate, a sensor unit 8 provided at the center of the base substrate 7, and the sensor unit 8 on the base substrate 7. And an electrode pad 9 for supplying a voltage to.

The sensor unit 8 includes an X-axis sensor 10, a Y-axis sensor 11, and a Z-axis sensor 12 as sensors for detecting angular velocities around three axes that are orthogonal in a three-dimensional space. These three sensors 10 to 12 are covered and sealed with the lid substrate 13 by bonding a lid substrate 13 made of, for example, a Si substrate to the base substrate 7.
The X-axis sensor 10 uses the vibration Ux in the X-axis direction to generate a Coriolis force Fz in the Z-axis direction when the MEMS package 1 is tilted, and detects a change in capacitance due to the Coriolis force. The angular velocity ωy acting around the Y axis is detected. Further, the Y-axis sensor 11 uses the vibration Uy in the Y-axis direction to generate a Coriolis force Fx in the X-axis direction when the MEMS package 1 is tilted, and detects a change in capacitance due to the Coriolis force. Thus, the angular velocity ωz acting around the Z axis is detected. Further, the Z-axis sensor 12 uses the vibration Uz in the Z-axis direction to generate a Coriolis force Fy in the Y-axis direction when the MEMS package 1 is tilted, and detects a change in capacitance due to the Coriolis force. Thus, the angular velocity ωx acting around the X axis is detected.

A plurality (seven in FIG. 1) of electrode pads 9 are provided at equal intervals along the width direction orthogonal to the longitudinal direction of the substrate 2.
A plurality of external terminals 4 (12 in FIG. 1) are provided at the other end in the longitudinal direction of the substrate 2 (the end opposite to the angular velocity sensor 3) at equal intervals along the width direction of the substrate 2. Is provided. Each external terminal 4 is formed through the substrate 2 in the thickness direction, and is exposed as an internal pad 14 on the surface of the substrate 2 and as an external pad 15 on the back surface of the substrate 2.

  The integrated circuit 5 is disposed between the angular velocity sensor 3 and the external terminal 4 (internal pad 14) on the surface side of the substrate 2. The integrated circuit 5 is made of, for example, a rectangular plate-like Si substrate that is long in the width direction of the substrate 2. Inside the Si substrate, a charge amplifier that amplifies the electrical signal output from each of the sensors 10 to 12, a filter circuit (low pass filter: LPF, etc.) that extracts a specific frequency component of the electrical signal, and an electrical signal after filtering A logic circuit or the like that performs a logical operation of the above is formed. These circuits are constituted by, for example, CMOS devices. Further, the integrated circuit 5 includes a first electrode pad 16 and a second electrode pad 17.

A plurality of (seven in FIG. 1) first electrode pads 16 are provided at equal intervals along the width direction of the substrate 2 at the end portion on the side close to the angular velocity sensor 3 in the longitudinal direction of the substrate 2. Yes. The first electrode pads 16 are connected to the electrode pads 9 of the angular velocity sensor 3 on a one-to-one basis by bonding wires 18.
A plurality of (two in FIG. 1) second electrode pads 17 are provided at equal intervals along the width direction of the substrate 2 at the end portion on the side close to the external terminal 4 in the longitudinal direction of the substrate 2. Yes. The second electrode pads 17 are connected to the internal pads 14 of the external terminals 4 on a one-to-one basis by bonding wires 19.

The resin package 6 forms the outer shape of the MEMS package 1 in cooperation with the substrate 2 and is formed in a substantially rectangular parallelepiped shape. The resin package 6 is made of, for example, a known mold resin such as an epoxy resin, covers the bonding wires 18 and 19 and the internal pads 14 together with the angular velocity sensor 3 and the integrated circuit 5, and exposes the external pads 15. The integrated circuit 5 is sealed.
<Configuration of X-axis sensor and Y-axis sensor>
Next, the configuration of the X-axis sensor and the Y-axis sensor will be described with reference to FIGS.

FIG. 2 is a schematic plan view of the angular velocity sensor shown in FIG. FIG. 3 is a plan view of an essential part of the X-axis sensor shown in FIG. 4 is a cross-sectional view of an essential part of the X-axis sensor shown in FIG. 2 and shows a cross section taken along a section AA in FIG.
As described above, the angular velocity sensor 3 includes the base substrate 7 made of a Si substrate. A concave portion 20 having a rectangular shape in plan view is formed on the surface layer portion of the base substrate 7 (portion facing the lid substrate 13 in the base substrate 7).

  On the base substrate 7, a base insulating layer 21 (for example, 2 μm to 10 μm thickness) as a base film and a polysilicon layer 22 (for example, 5 μm to 20 μm thickness) are sequentially stacked so as to cover the recess 20. . As a result, a cavity 23 defined by the base insulating layer 21 and the base substrate 7 is formed in the laminated structure including the base substrate 7, the base insulating layer 21 and the polysilicon layer 22 included in the angular velocity sensor 3.

The X-axis sensor 10, the Y-axis sensor 11, and the Z-axis sensor 12 have a laminated structure of a base insulating layer 21 and a polysilicon layer 22, and are disposed immediately above the cavity 23. That is, the X-axis sensor 10, the Y-axis sensor 11, and the Z-axis sensor 12 are provided in a state of floating with respect to the bottom wall 24 of the base substrate 7 that forms the bottom surface that defines the cavity 23 from the back surface side.
The X-axis sensor 10 and the Y-axis sensor 11 are disposed adjacent to each other with a space therebetween. A Z-axis sensor 12 is disposed so as to surround each of the X-axis sensor 10 and the Y-axis sensor 11.

In this embodiment, the Y-axis sensor 11 has substantially the same configuration as that obtained by rotating the X-axis sensor 10 by 90 ° in plan view. Therefore, in the following, regarding the configuration of the Y-axis sensor 11, when describing each part of the X-axis sensor 10, the part corresponding to each part is written together in parentheses and replaced with a specific description.
A support portion 25 is formed between the X-axis sensor 10 and the Z-axis sensor 12 and between the Y-axis sensor 11 and the Z-axis sensor 12 to support them in a floating state.

The support portion 25 has a laminated structure of the base substrate 7, the base insulating layer 21 and the polysilicon layer 22, and integrally includes a straight portion 26 and an annular portion 27.
The linear portion 26 of the support portion 25 extends from one side wall 28 of the laminated structure forming a side surface that divides the cavity 23 from the side, across the Z-axis sensor 12 toward the X-axis sensor 10 and the Y-axis sensor 11. ing. Further, the annular portion 27 of the support portion 25 surrounds the X-axis sensor 10 and the Y-axis sensor 11.

The X-axis sensor 10 and the Y-axis sensor 11 are disposed inside each annular portion 27 and are supported at two opposite positions on the inner wall of the annular portion 27. The Z-axis sensor 12 is supported at both side walls of the linear portion 26.
The X-axis sensor 10 (Y-axis sensor 11) has an X fixed electrode 31 (Y fixed electrode 51) and an X movable electrode 32 (Y movable electrode 52) formed with the same thickness.

The X fixed electrode 31 (Y fixed electrode 51) is fixed to a support portion 25 provided in the cavity 23.
Further, the X fixed electrode 31 (Y fixed electrode 51) includes a first base portion 33 (first base portion 53 of the Y fixed electrode 51) that is fixed to the support portion 25 and has a square shape in plan view, and a first base portion 33. And a plurality of sets of first comb teeth 34 (first comb teeth 54 of the Y fixed electrode 51) arranged in a comb shape at equal intervals along the inner wall.

The first base portion 33 of the X fixed electrode 31 includes a linear main frame extending in parallel with each other and a reinforcing frame combined with the main frame so that a triangular space is repeated along the main frame. It has a truss-like framework structure.
The first comb-teeth portion 34 of the X fixed electrode 31 includes a pair of two electrode portions each having a linear shape in plan view, each base end portion of which is connected to the first base portion 33 and the tip portions thereof facing each other. Are provided at equal intervals. Each first comb tooth portion 34 has a ladder structure in a planar view including a linear main frame extending in parallel to each other and a plurality of horizontal frames constructed between the main frames.

The X movable electrode 32 (Y movable electrode 52) is held so as to be able to vibrate with respect to the X fixed electrode 31.
The X movable electrode 32 (Y movable electrode 52) includes a second base portion 35 (second base portion 55 of the Y movable electrode 52) and a second comb tooth portion 36 (second comb tooth portion of the Y movable electrode 52). 56).

The second base portion 35 of the X movable electrode 32 is formed from a plurality of (six in this embodiment) linear frames extending in parallel with each other along the direction crossing the first comb tooth portion 34 of the X fixed electrode 31. Become. Both ends of each second base portion 35 are connected to a beam portion 37 (a beam portion 57 of the Y-axis sensor 11) that can expand and contract along a direction crossing the first comb tooth portion 34.
Two beam portions 37 are provided at both ends of the second base portion 35 of the X movable electrode 32.

  The second comb teeth portion 36 of the X movable electrode 32 extends from the second base portion 35 to both sides of the first comb teeth portions 34 of the X fixed electrodes 31 adjacent to each other. They are arranged in a comb-teeth shape so as not to contact the comb-teeth part 34. The second comb tooth portion 36 includes a linear main frame that extends in parallel with each other across the frames of the second base portion 35 and a plurality of horizontal frames that are spanned between the main frames. It has a frame structure.

In the X movable electrode 32, the horizontal frame is traversed from the surface of the polysilicon layer 22 to the base insulating layer 21 on a line that bisects each second comb tooth portion 36 along the direction orthogonal to the vibration direction Ux. An insulating layer 38 is embedded.
The insulating layer 38 is made of SiO ₂ (silicon oxide) and is formed integrally with the base insulating layer 21. Each second comb-tooth portion 36 is insulated and separated by the insulating layer 38 into two on one side and the other side along the vibration direction Ux. As a result, the separated second comb teeth 36 of the X movable electrode 32 function as independent electrodes in the X movable electrode 32.

On the polysilicon layer 22, a first insulating film 42 and a second insulating film 43 made of SiO ₂ are sequentially stacked. An X first drive / detection wiring 39 (Y first drive / detection wiring 59) and an X second drive / detection wiring 40 (Y second drive / detection wiring 60) are formed on the second insulating film 43. Yes.
The X first drive / detection wiring 39 supplies a drive voltage to one side (in this embodiment, the left side in FIG. 3) of each second comb-tooth portion 36 that is insulated and separated into two, and the second A change in voltage associated with a change in capacitance is detected from the comb tooth portion 36.

The X second drive / detection wiring 40 supplies a drive voltage to the other side (in this embodiment, the right side of FIG. 3) of each second comb-tooth portion 36 that is insulated and separated into two, and the second A change in voltage associated with a change in capacitance is detected from the comb tooth portion 36.
In this embodiment, the X first drive / detection wiring 39 and the X second drive / detection wiring 40 are made of Al (aluminum). The X first drive / detection wiring 39 and the X second drive / detection wiring 40 penetrate the first insulating film 42 and the second insulating film 42 and are electrically connected to the second comb teeth 36.

The X first drive / detection wiring 39 and the X second drive / detection wiring 40 are routed on the support portion 25 via the beam portion 37 of the X movable electrode 32 and the first base portion 33 of the X fixed electrode 31. A part of the electrode pad 9 is exposed.
Note that the X first drive / detection wiring 39 and the X second drive / detection wiring 40 each include a beam made of a part of the conductive polysilicon layer 22 in a section passing through the beam portion 37 of the X movable electrode 32. The part 37 itself is used as a current path. Since it is not necessary to provide Al wiring on the beam portion 37, the stretchability of the beam portion 37 can be maintained.

In addition, an X third drive / detection wiring 41 for detecting a change in voltage accompanying a change in capacitance is routed from the first comb tooth portion 34 of the X fixed electrode 31 to the support portion 25. A part of the X third drive / detection wiring 41 is exposed as an electrode pad 9 (not shown), like the other wirings 39 and 40.
The upper surface and side surfaces of the X fixed electrode 31 and the X movable electrode 32 are covered with a protective thin film 44 made of SiO ₂ so as to cover the first insulating film 42 and the second insulating film 43.

On the polysilicon layer 22, a third insulating film 45, a fourth insulating film 46, a fifth insulating film 47, and a surface protective film 48 are sequentially stacked on the second insulating film 43 in a portion outside the cavity 23. Has been.
In the X-axis sensor 10 having the above-described structure, driving voltages having the same polarity / different polarity between the X fixed electrode 31 and the X movable electrode 32 via the X first to X third driving / detecting wirings 39 to 41. Are given alternately. Thereby, a Coulomb repulsive force / Coulomb attractive force is alternately generated between the first comb tooth portion 34 of the X fixed electrode 31 and the second comb tooth portion 36 of the X movable electrode 32.

As a result, the comb-shaped X movable electrode 32 vibrates left and right (vibrates Ux) along the X-axis direction with respect to the comb-shaped X fixed electrode 31.
In this state, when the X movable electrode 32 rotates about the Y axis, a Coriolis force Fz is generated in the Z axis direction. Due to the Coriolis force Fz, the facing area and / or distance between the first comb teeth 34 of the X fixed electrodes 31 and the second comb teeth 36 of the X movable electrode 32 that are adjacent to each other changes.

Then, the angular velocity ωy about the Y axis is detected by detecting the change in capacitance between the X movable electrode 32 and the X fixed electrode 31 due to the change in the facing area and / or the distance.
In this embodiment, the angular velocity ωy about the Y-axis is obtained by taking the difference between the detection values of one and the other electrode portions of the X movable electrode 32 that is insulated and separated.

In the Y-axis sensor 11, drive voltages of the same polarity / different polarity are alternately connected between the Y fixed electrode 51 and the Y movable electrode 52 via the Y first to Y third drive / detection wirings 59 to 61. Given to. Thereby, a Coulomb repulsive force / Coulomb attractive force is alternately generated between the first comb tooth portion 54 of the Y fixed electrode 51 and the second comb tooth portion 56 of the Y movable electrode 52.
As a result, the comb-shaped Y movable electrode 52 vibrates left and right (vibrates Uy) along the Y-axis direction with respect to the comb-shaped Y fixed electrode 51.

In this state, when the Y movable electrode 52 rotates about the Y axis as a central axis, a Coriolis force Fx is generated in the X axis direction. Due to this Coriolis force Fx, the facing area and / or distance between the first comb teeth portion 54 of the Y fixed electrode 51 and the second comb teeth portion 56 of the Y movable electrode 52 that are adjacent to each other changes.
Then, the angular velocity ωz around the Z axis is detected by detecting the change in capacitance between the Y movable electrode 52 and the Y fixed electrode 51 due to the change in the facing area and / or the distance.
<Configuration of Z-axis sensor>
Next, the configuration of the Z-axis sensor will be described with reference to FIGS. 2 and 5 to 6.

FIG. 5 is a plan view of the main part of the Z-axis sensor shown in FIG. 6 is a cross-sectional view of the main part of the Z-axis sensor shown in FIG. 2, and shows a cross section taken along a cutting plane BB in FIG. 5.
As described above, the Z-axis sensor 12 is disposed so as to surround each of the X-axis sensor 10 and the Y-axis sensor 11 immediately above the cavity 23.
The Z-axis sensor 12 has a Z fixed electrode 71 and a Z movable electrode 72 that are formed with the same thickness and width. 5 and 6, the thickness and width of the Z stationary electrode 71, respectively and a thickness of T ₁ and width W _1, the thickness and width of the Z movable electrode 72, respectively the _second thickness T ₂ and W ₂ is there.

The Z fixed electrode 71 is fixed to a support part 25 (straight line part 26) provided in the cavity 23.
The Z movable electrode 72 is held so as to be able to vibrate with respect to the Z fixed electrode 71.
In this embodiment, in one of the two Z-axis sensors 12, the Z-movable electrode 72 is disposed so as to surround the annular portion 27, and the Z-fixed so as to surround the Z-movable electrode 72. An electrode 71 is disposed.

In the other Z-axis sensor 12, the Z fixed electrode 71 is disposed so as to surround the annular portion 27, and the Z movable electrode 72 is disposed so as to surround the Z fixed electrode 71.
In each Z-axis sensor 12, the Z fixed electrode 71 includes a first base portion 73 and a plurality of first comb teeth portions 74.
The first base portion 73 of the Z fixed electrode 71 is formed in a square ring shape in plan view fixed to the support portion 25. The first base 73 has a truss shape having a linear main frame extending in parallel to each other and a reinforcing frame combined with the main frame so that a triangular space is repeated along the main frame. It has the framework structure.

A truss structure is formed on both sides of a portion (opposing portion 75) of the first base portion 73 that faces a tip portion 82 (described later) of each second comb tooth portion 79 from the surface of the polysilicon layer 22 to the cavity 23. An insulating layer 76 is embedded across the main frame in the width direction.
The insulating layer 76 is made of SiO ₂ and is formed integrally with the base insulating layer 21. Accordingly, the facing portion 75 surrounded by the insulating layer 76 and the triangular space of the truss structure is insulated from the other portions of the first base portion 73 of the Z fixed electrode 71.

The first comb-teeth portion 74 of the Z fixed electrode 71 is formed on the first base portion 73 on the opposite side of the linear portion 26 with respect to the X-axis sensor 10 (Y-axis sensor 11). They are arranged in a comb-like shape at equal intervals along the inner wall.
Each first comb tooth portion 74 has a proximal end portion connected to the first base portion 73 of the Z fixed electrode 71 and a distal end portion extending toward the Z movable electrode 72. In addition, an insulating layer 77 is embedded in the portion near the base end portion of each first comb tooth portion 74 so as to cross the first comb tooth portion 74 in the width direction from the surface of the polysilicon layer 22 to the cavity 23. Yes.

The insulating layer 77 is made of SiO ₂ and is formed integrally with the base insulating layer 21. Each first comb tooth portion 74 is insulated from other portions of the Z fixed electrode 71 by an insulating layer 77.
In each Z-axis sensor 12, the Z movable electrode 72 includes a second base portion 78 and a second comb tooth portion 79.
The second base portion 78 of the Z movable electrode 72 is formed in a square ring shape in plan view. The second base 78 has a truss shape having a linear main frame extending parallel to each other and a reinforcing frame combined with the main frame so that a triangular space is repeated along the main frame. It has the framework structure.

The second base portion 78 of the framework structure has a section in which the reinforcing frame is omitted at a portion opposite to the side where the second comb tooth portion 79 is disposed. The main frame in the omitted section functions as a beam unit 80 for enabling the Z movable electrode 72 to move up and down.
The second comb tooth portion 79 of the Z movable electrode 72 extends from the second base portion 78 toward each of the first comb tooth portions 74 of the Z fixed electrodes 71 adjacent to each other, and contacts the first comb tooth portion 74. It is arranged in a comb-teeth shape that meshes with each other.

Each second comb-tooth portion 79 has a base end portion 81 connected to the second base portion 78 of the Z movable electrode 72 and a distal end portion 82 extending between the first comb-teeth portions 74 of the Z fixed electrode 71. ing.
An insulating layer 84 that crosses the second comb tooth 79 in the width direction from the surface of the polysilicon layer 22 to the cavity 23 is embedded in a portion near the tip 82 of each second comb tooth 79. Further, an insulating layer 85 is embedded in the portion of each second comb tooth 79 near the base end portion 81 from the surface of the polysilicon layer 22 to the cavity 23 so as to cross the second comb tooth 79 in the width direction. ing.

The insulating layers 84 and 85 are made of SiO ₂ and are formed integrally with the base insulating layer 21. Each of the second comb teeth 79 is insulated from the other portions by the insulating layers 84 and 85, and the three portions (the distal end portion 82, the proximal end portion 81, and the intermediate portion between the distal end portion 82 and the proximal end portion 81 are separated. Part 83).
As described above, the first insulating film 42 and the second insulating film 43 made of SiO ₂ are sequentially stacked on the polysilicon layer 22. On the second insulating film 43, a Z first detection wiring 86, a Z first drive wiring 87, a Z second detection wiring 88, and a Z second drive wiring 89 are formed.

  The Z first detection wiring 86 and the Z second detection wiring 88 are respectively connected to the first comb tooth portion 74 of the Z fixed electrode 71 and the intermediate portion 83 of the Z movable electrode 72 which are adjacent to each other. That is, in the Z-axis sensor 12, the first comb tooth portion 74 of the Z fixed electrode 71 and the intermediate portion 83 of the Z movable electrode 72 face each other with an interelectrode distance d therebetween, and a constant voltage is applied between them. Thus, an electrode of a capacitive element (detection unit) whose electrostatic capacitance is changed by a change in the inter-electrode distance d and / or the facing area is configured.

Specifically, the Z first detection wiring 86 is formed along the first base portion 73 and straddles the insulating layer 77 of each first comb tooth portion 74 toward the tip portion of the first comb tooth portion 74. Branched Al wiring is included.
The branched Al wiring penetrates through the first insulating film 42 and the second insulating film 43 and is electrically connected to the front end side of the insulating layer 77 in each first comb tooth portion 74.

As shown in FIG. 2, the Z first detection wiring 86 is routed on the support portion 25 via the first base portion 73, and a part of the Z detection wire 86 is exposed as the electrode pad 9.
The Z second detection wiring 88 detects a change in voltage accompanying a change in capacitance from the second comb tooth 79 of the Z movable electrode 72. The Z second detection wiring 88 is formed along the second base portion 78 and is an Al wiring that branches toward the intermediate portion 83 across the insulating layer 85 near the base end portion 81 of each second comb tooth 79. Contains.

The branched Al wirings are electrically connected through the first insulating film 42 and the second insulating film 43 in the intermediate portion 83 of each second comb tooth 79.
Further, as shown in FIG. 2, the Z second detection wiring 88 is routed on the support portion 25 via the second base portion 78 of the Z movable electrode 72, and a part thereof is exposed as the electrode pad 9. Yes.
The Z first drive wiring 87 and the Z second drive wiring 89 are respectively connected to a facing portion 75 and a tip portion 82 facing each other in a direction orthogonal to the facing direction of the electrodes constituting the capacitive element. That is, in the Z-axis sensor 12, a driving voltage is applied between the opposing portion 75 of the Z fixed electrode 71 and the distal end portion 82 of the Z movable electrode 72 that are opposed to each other with a space therebetween, and the voltage change of the driving voltage The drive part which vibrates Z movable electrode 72 with the Coulomb force which generate | occur | produces by this is comprised.

  Specifically, the Z first drive wiring 87 supplies a drive voltage to the facing portion 75 of the Z fixed electrode 71. The Z first drive wiring 87 includes Al wiring straddling both sides of the insulating layer 76 using the surface of the second insulating film 43. The Z first drive wiring 87 is electrically connected through the first insulating film 42 and the second insulating film 43 in a portion excluding the facing portion 75 and the facing portion 75 of the first base portion 73. The remaining portion of the Z first drive wiring 87 excluding the Al wiring is configured using the first base portion 73 made of the conductive polysilicon layer 22.

Further, as shown in FIG. 2, the Z first drive wiring 87 is routed on the support portion 25, and a part thereof is exposed as the electrode pad 9.
The Z second drive wiring 89 supplies a drive voltage to the tip portion 82 of the Z movable electrode 72. The Z second drive wiring 89 includes Al wiring straddling between the distal end portion 82 and the proximal end portion 81 of the second comb tooth portion 79 using the surface of the second insulating film 43. The Z second drive wiring 89 is electrically connected through the first insulating film 42 and the second insulating film 43 at the distal end portion 82 and the proximal end portion 81. The remaining portion of the Z second drive wiring 89 excluding the Al wiring is configured using the second base portion 78 made of the conductive polysilicon layer 22.

Further, as shown in FIG. 2, the Z second drive wiring 89 is routed on the support portion 25, and a part thereof is exposed as the electrode pad 9.
The upper surfaces and side surfaces of the Z fixed electrode 71 and the Z movable electrode 72 are covered with a protective thin film 44 made of SiO ₂ so as to cover the first insulating film 42 and the second insulating film 43.
In the Z-axis sensor 12 having the above structure, the Z-axis sensor 12 is connected between the opposing portion 75 of the Z fixed electrode 71 and the tip portion 82 of the Z movable electrode 72 via the Z first drive wiring 87 and the Z second drive wiring 89. Polarity / different polarity drive voltages are alternately applied. As a result, a Coulomb repulsive force / Coulomb attractive force is alternately generated between the facing portion 75 and the tip portion 82.

As a result, as if the comb-shaped Z movable electrode 72 is a pendulum, the comb-shaped Z fixed electrode 71 is also vertically centered on the Z fixed electrode 71 along the Z-axis direction. It vibrates (vibrates Uz).
In this state, when the Z movable electrode 72 rotates about the X axis, a Coriolis force Fy is generated in the Y axis direction. Due to this Coriolis force Fy, the facing area between the first comb teeth 74 adjacent to each other and the intermediate portion 83 of the second comb teeth 79 and / or the inter-electrode distance d changes.

The angular velocity ωx around the X axis is detected by detecting a change in the capacitance C between the Z movable electrode 72 and the Z fixed electrode 71 due to the change in the facing area and / or the interelectrode distance d. .
In this embodiment, the angular velocity ωx around the X axis is obtained by taking the difference between the detection value of the Z axis sensor 12 surrounding the X axis sensor 10 and the detection value of the Z axis sensor 12 surrounding the Y axis sensor 11. Desired.

For example, as shown in FIG. 2, the difference is the positional relationship between the fixed and movable electrodes of the Z-axis sensor 12 surrounding the X-axis sensor 10 and the fixed and movable electrodes of the Z-axis sensor 12 surrounding the Y-axis sensor 11. Can be obtained by reversing. As a result, the way in which the Z movable electrode 72 swings between the pair of Z-axis sensors 12 is different, so that a difference occurs.
<Manufacturing method of angular velocity sensor>
Next, with reference to FIGS. 7A to 7K, the manufacturing process of the angular velocity sensor described above will be described in the order of steps. In this section, only the manufacturing process of the Z-axis sensor is illustrated and the manufacturing process of the X-axis sensor and the Y-axis sensor is omitted, but the manufacturing process of the X-axis sensor and the Y-axis sensor is the manufacturing process of the Z-axis sensor. In the same manner as described above, it is executed in parallel with the manufacturing process of the Z-axis sensor.

7A to 7K are schematic cross-sectional views showing a part of the manufacturing process of the Z-axis sensor shown in FIG. 2 in the order of steps, and show a cut surface at the same position as FIG. 6.
In order to manufacture the Z-axis sensor 12, the surface of the base substrate 7 made of conductive silicon is thermally oxidized (for example, temperature 1000 ° C. to 1200 ° C.). As a result, a mask (not shown) made of SiO ₂ is formed on the surface of the base substrate 7. Next, the mask is patterned by a known patterning technique, and an opening is formed in a portion covering a region other than a region where the insulating layers 76, 77, 84, and 85 are to be formed.

Next, a trench (for example, a depth is selectively formed in the base substrate 7 by anisotropic deep RIE (reactive ion etching) using the mask as a hard mask, specifically, by a Bosch process. About 10 μm) is formed. In the Bosch process, the process of etching the base substrate 7 using SF ₆ (sulfur hexafluoride) and the process of forming a protective film on the etched surface using C ₄ F ₈ (perfluorocyclobutane) are alternated. Repeated. Thereby, the base substrate 7 can be etched with a high aspect ratio, but wavy irregularities called scallops are formed on the etched surface (inner peripheral surface of the trench).

As a result, as shown in FIG. 7A, the columnar portion remaining without forming the trench in the base substrate 7 is formed as the columnar portion 29 having the same shape as the insulating layers 76, 77, 84, and 85. A plate-like base portion 30 that integrally supports the bottom portion of the columnar portion 29 is formed at the same time.
Next, as shown in FIG. 7B, the columnar portion 29 and the base portion 30 of the base substrate 7 are thermally oxidized (for example, a temperature of 1000 ° C. to 1200 ° C.). As a result, the entire columnar portion 29 and the surface layer portion of the base portion 30 are transformed into an insulating film made of SiO ₂ . In the altered insulating films, the columnar portion 29 becomes the insulating layers 76, 77, 84, and 85, and the surface layer portion of the base portion 30 becomes the base insulating layer 21.

  Next, a seed film made of polysilicon is formed on the surfaces of the insulating layers 76, 77, 84, 85 and the base insulating layer 21. Subsequently, polysilicon is epitaxially grown from the seed film. In this epitaxial growth, as shown in FIG. 7C, the height of the growing polysilicon layer 22 is changed to the top of the columnar portion 29 in which the height is changed to the insulating layers 76, 77, 84, 85 (in FIG. 7C, the top 49 of the insulating layer 85). Will continue until it becomes higher.

Next, as shown in FIG. 7D, the surface of the polysilicon layer 22 is subjected to a CMP (Chemical Mechanical Polishing) process, whereby the surface of the polysilicon layer 22 and the top of the columnar portion 29 (insulating layer 85). 49. The top portion 49 of the columnar portion 29 is exposed on the surface of the polysilicon layer 22.
Next, as shown in FIG. 7E, a first insulating film 42 made of SiO ₂ is stacked on the polysilicon layer 22 by a CVD method.

  Next, as illustrated in FIG. 7F, the second insulating film 43 is stacked on the first insulating film 42. Subsequently, the second insulating film 43 and the first insulating film 42 are continuously etched. As a result, contact holes are formed in the second insulating film 43 and the first insulating film 42. Subsequently, after a contact plug filling up the contact hole is formed, Al is deposited on the second insulating film 43 (for example, 7000 mm) by sputtering, and the Al deposited layer is patterned. As a result, wirings 86 to 89 are formed on the second insulating film 43.

Next, as shown in FIG. 7G, a third insulating film 45, a fourth insulating film 46, a fifth insulating film 47, and a surface protective film 48 are sequentially stacked on the second insulating film 43 by a CVD method. Next, the third to fifth insulating films 45 to 47 and the surface protective film 48 on the region where the recess 20 of the base substrate 7 is to be formed are removed by etching.
Next, as shown in FIG. 7H, a resist having an opening in a region other than the region where the Z fixed electrode 71 and the Z movable electrode 72 are to be formed is formed on the second insulating film 43. Subsequently, the polysilicon layer 22 and the base insulating layer 21 are dug in order by anisotropic deep RIE using the resist as a mask, specifically, by a Bosch process. Thereby, the laminated structure of the base insulating layer 21 and the polysilicon layer 22 is formed into the shape of the Z fixed electrode 71 as the first electrode or the second electrode and the Z movable electrode 72 as the first electrode or the second electrode. In addition, a trench 50 is formed between them. The surface of the base substrate 7 is exposed at the bottom surface of the trench 50.

Next, as shown in FIG. 7I, by the thermal oxidation method or the PECVD method, the entire surface of the Z fixed electrode 71, the Z movable electrode 72 and the entire inner surface of the trench 50 (that is, the side surface and the bottom surface defining the trench 50) A protective thin film 44 made of SiO ₂ is formed.
Next, as shown in FIG. 7J, the portion of the protective thin film 44 on the bottom surface of the trench 50 is removed by etch back. As a result, the bottom surface of the trench 50 is exposed.

Next, as shown in FIG. 7K, the bottom surface of the trench 50 (that is, the surface of the base substrate 7) is further dug down by anisotropic deep RIE using the surface protective film 48 as a mask. Thereby, an exposed space 58 in which the crystal plane of the base substrate 7 is exposed is formed at the bottom of the trench 50 (surface layer portion of the base substrate 7).
Subsequent to this anisotropic deep RIE, reactive ions and etching gas as an etching medium are supplied to the exposed space 58 of the trench 50 by isotropic RIE. The base substrate 7 is etched in the direction parallel to the surface of the base substrate 7 while being etched in the thickness direction of the base substrate 7 starting from each exposed space 58 by the action of the reactive ions and the like. Accordingly, all the exposed spaces 58 adjacent to each other are integrated to form the recess 20 (cavity 23) in the surface layer portion of the base substrate 7, and the Z fixed electrode 71 and the Z movable electrode 72 are directly above the recess 20. Will be in a floating state.

Through the above steps, the Z-axis sensor 12 shown in FIG. 2 is obtained.
According to the above method, the lowermost portions of the Z fixed electrode 71 and the Z movable electrode 72 are constituted by the base insulating layer 21 made of SiO ₂ having an etching selectivity with respect to Si. Further, the side surfaces of the Z fixed electrode 71 and the Z movable electrode 72 are similarly covered with the protective thin film 44 made of SiO ₂ .

For this reason, in the step shown in FIG. 7K, when the base substrate 7 is isotropically etched by supplying reactive ions and etching gas to the exposed space 58, the etching gas or the like comes into contact with the Z fixed electrode 71 and the Z movable electrode 72. However, erosion of the Z fixed electrode 71 and the Z movable electrode 72 by the etching gas can be prevented. As a result, variations in the sizes (thicknesses T ₁ and T ₂ and widths W ₁ and W ₂ ) of the Z fixed electrode 71 and the Z movable electrode 72 can be reduced.

Therefore, in the Z-axis sensor 12, the facing area between the first comb tooth portion 74 and the intermediate portion 83 of the second comb tooth portion 79 according to the thicknesses T ₁ and T ₂ of the Z fixed electrode 71 and the Z movable electrode 72, In addition, the inter-electrode distance d corresponding to the widths W ₁ and W ₂ of the Z fixed electrode 71 and the Z movable electrode 72 can be kept constant. Therefore, it is possible to accurately detect a change in capacitance between the Z movable electrode 72 and the Z fixed electrode 71 due to the change in the facing area and / or the inter-electrode distance d.

In addition, since the variations in the widths W ₁ and W ₂ of the Z fixed electrode 71 and the Z movable electrode 72 are small, the Coulomb repulsive force / Coulomb attractive force of approximately the same magnitude is provided between the facing portion 75 and the tip portion 82. Can be generated. As a result, the Z movable electrode 72 can be driven as designed.
By the way, in invention of patent document 1, the several part which should be electrically insulated in Si substrate is isolate | separated by the isolation | separation joint (Isolation joint 160,360 ...). As shown in FIG. 6a of Patent Document 1, the separation joint is formed by forming a trench in a Si substrate and thermally oxidizing the inner walls (side walls and bottom wall) of the trench. When the inner wall of the trench is thermally oxidized, SiO ₂ is grown from the side and bottom walls towards the inside of the trench, SiO ₂ with each other to any integrated grown from each wall. By this integration, a separation joint embedded in the trench (612 in FIG. 6a) is obtained. However, since the isolation joint obtained in this way is a film formed by growing a plurality of SiO ₂ inside the trench that was originally empty and integrating them, its strength is not so high, It takes time to form (for example, the etching rate is about 2 μm / h).

  Therefore, in this embodiment, the shape of the insulating layers 76, 77, 84, 85 for insulating and isolating each part of the Z fixed electrode 71 and the Z movable electrode 72 from the other parts is changed to a base substrate 7 having a crystal structure. The columnar portion 29 is formed by etching (step of FIG. 7A). Next, the columnar portion 29 is thermally oxidized to be transformed into an insulating film (step of FIG. 7B). Next, a polysilicon layer 22 is formed around the insulating film (steps of FIGS. 7C to 7D), and the polysilicon layer 22 is etched into the shape of the Z fixed electrode 71 and the Z movable electrode 72 (step of FIG. 7H). ). That is, since the shape of the insulating layers 76, 77, 84, 85 is formed by etching the base substrate 7, it is shorter than the method for forming the separation joint of Patent Document 1 (for example, the etching rate is 5 μm to 10 μm). / Min) as an insulating layer having high strength.

  Further, as shown in FIG. 7C, after the polysilicon is epitaxially grown so as to completely cover the insulating layers 76, 77, 84, 85, the thickness of the polysilicon layer 22 is obtained by subjecting the grown polysilicon to a CMP process. Is adjusted. Therefore, the polysilicon layer having the same thickness as the insulating film made of the columnar portion 29 is compared with the case where the thickness of the polysilicon layer 22 is adjusted in consideration of the growth time of polysilicon grown from the seed film. 22 can be formed easily. Thereby, the first comb tooth portion 74 and the facing portion 75 of the Z fixed electrode 71 and the proximal end portion 81, the distal end portion 82 and the intermediate portion 83 of the Z movable electrode 72 are surely separated from the other portions of the polysilicon layer 22. Can be insulated.

  7F, wirings 86 to 89 are formed on the polysilicon layer 22 prior to the step of forming the polysilicon layer 22 into the Z fixed electrode 71 and the Z movable electrode 72 (step of FIG. 7H). Is done. If the electrodes 71 and 72 are not yet formed, the space on the polysilicon layer 22 can be used effectively. Even if a slight error occurs between the actual formation pattern of the wirings 86 to 89 and the formation pattern of the design specification, if the forming pattern of the electrodes 71 and 72 is corrected in consideration of the error, finally, A sensor as designed can be manufactured.

In addition, although description is abbreviate | omitted about the effect of the X-axis sensor 10 and the Y-axis sensor 11, the X-axis sensor 10 and the Y-axis sensor 11 of this embodiment are provided with the structure shown in FIGS. The same effects as the Z-axis sensor 12 described above can be exhibited.
And since the MEMS package 1 of this embodiment is provided with the X-axis sensor 10, the Y-axis sensor 11, and the Z-axis sensor 12, it is three axes (X axis, Y axis, and Z axis) orthogonal in three-dimensional space. Angular velocity acting around can be detected with high accuracy.

As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.
For example, the MEMS package 1 may include an acceleration sensor instead of the angular velocity sensor 3 or together with the angular velocity sensor 3. The acceleration sensor can be manufactured, for example, by omitting the driving unit in each of the sensors 10 to 12 shown in FIGS. For example, as shown in FIG. 8, the Z-axis acceleration sensor 90 that detects acceleration acting in the Z-axis direction includes a facing portion 75 of the Z fixed electrode 71 that functions as a driving portion in the Z-axis sensor 12 shown in FIG. It can be manufactured by omitting the tip end portion 82 of the Z movable electrode 72 and the wirings 87 and 89 connected thereto.

In the Z-axis acceleration sensor 90, variations in the sizes (thicknesses T ₁ and T ₂ and widths W ₁ and W ₂ ) of the Z fixed electrode 71 and the Z movable electrode 72 can be reduced.
Therefore, in the Z-axis acceleration sensor 90, the opposing area between the first comb tooth portion 74 and the intermediate portion 83 of the second comb tooth portion 79 according to the thicknesses T ₁ and T ₂ of the Z fixed electrode 71 and the Z movable electrode 72. The inter-electrode distance d corresponding to the widths W ₁ and W ₂ of the Z fixed electrode 71 and the Z movable electrode 72 can be kept constant. Therefore, it is possible to accurately detect a change in capacitance between the Z movable electrode 72 and the Z fixed electrode 71 due to the change in the facing area and / or the inter-electrode distance d. As a result, it is possible to accurately detect the acceleration based on the change amount of the capacitance.

In addition, the insulating base layer 21 is not limited to SiO ₂ , but may be another material (for example, SiN) having an etching selectivity with respect to Si.
In addition, various design changes can be made within the scope of matters described in the claims.

DESCRIPTION OF SYMBOLS 1 MEMS package 2 Board | substrate 3 Angular velocity sensor 5 Integrated circuit 6 Resin package 7 Base board 10 X-axis sensor 11 Y-axis sensor 12 Z-axis sensor 20 Recessed part 21 Base insulating layer 22 Polysilicon layer 23 Cavity 29 Column-shaped part 30 Base part 31 X fixation Electrode 32 X Movable electrode 34 1st comb tooth part (X fixed electrode)
36 2nd comb tooth part (X movable electrode)
38 Insulating Layer 39 X First Drive / Detection Wiring 40 X Second Drive / Detection Wiring 41 X Third Drive / Detection Wiring 44 Protective Thin Film 49 Top 50 Trench 51 Y Fixed Electrode 52 Y Movable Electrode 54 First Comb Tooth (Y Fixed electrode)
56 2nd comb tooth part (Y movable electrode)
59 Y first drive / detection wiring 60 Y second drive / detection wiring 61 Y third drive / detection wiring 71 Z fixed electrode 72 Z movable electrode 74 first comb tooth portion (Z fixed electrode)
75 Opposite part 76 Insulating layer 77 Insulating layer 79 Second comb tooth part (Z movable electrode)
81 Base end portion 82 Front end portion 83 Intermediate portion 84 Insulating layer 85 Insulating layer 86 Z first detecting wiring 87 Z first driving wiring 88 Z second detecting wiring 89 Z second driving wiring 90 Z-axis acceleration sensor

Claims (18)

Forming a base film made of a material having an etching selectivity with respect to Si on a Si substrate;
Forming a polysilicon layer on the base film;
A trench extending from the surface of the polysilicon layer to the surface of the Si substrate is formed by selectively etching the polysilicon layer and the base film, and at the same time, a laminated structure of the base film and the polysilicon layer Forming a comb-shaped first electrode and a second electrode that mesh with each other across the trench, and
And a step of etching a portion of the Si substrate immediately below the base film by isotropic etching to supply an etching medium to the trench to form a cavity immediately below the base film. The step of forming the base film includes
Selectively etching the Si substrate to process the Si substrate into a plate-like base portion and a columnar portion erected on the surface of the base portion;
Changing the surface of the base part and the columnar part into an insulating film by thermally oxidizing the surface of the base part and the columnar part,
Selectively etching the polysilicon layer and the base film,
2. The method according to claim 1, further comprising: etching the first electrode and / or the second electrode so that the first electrode and / or the second electrode are insulated from other portions of the polysilicon layer by the columnar portion transformed into the insulating film. Manufacturing method of a MEMS sensor. The step of forming the polysilicon layer includes:
Depositing a polysilicon material on the base portion to a position higher than the top of the columnar portion;
3. The method of manufacturing a MEMS sensor according to claim 2, further comprising a step of grinding the polysilicon material until a surface of the deposited polysilicon material reaches a height position of the top portion of the columnar portion.   The MEMS according to claim 1, further comprising a step of forming a protective film having an etching selectivity with respect to polysilicon so as to cover side walls of the first electrode and the second electrode. Sensor manufacturing method.   5. The method of manufacturing a MEMS sensor according to claim 1, further comprising a step of selectively forming a wiring on the polysilicon layer prior to the formation of the trench. 6. A Si substrate having a surface layer portion in which a recess is formed;
Comb-like shape that is disposed immediately above the concave portion of the Si substrate and has a laminated structure of a base film and a polysilicon layer made of an insulating material laminated in order from the side close to the concave portion, and meshes with each other at an interval. A MEMS sensor comprising a first electrode and a second electrode.   A first insulating layer embedded in the first electrode so as to penetrate the polysilicon layer and reach the base film, and selectively insulates a part of the first electrode from the other part of the polysilicon layer The MEMS sensor according to claim 6, further comprising:   A first insulating layer embedded in the second electrode so as to penetrate the polysilicon layer and reach the base film, and selectively insulates a part of the second electrode from the other part of the polysilicon layer The MEMS sensor according to claim 6 or 7, further comprising:   The MEMS sensor according to any one of claims 6 to 8, wherein the first electrode is a movable electrode and the second electrode is a fixed electrode.   The MEMS sensor according to any one of claims 6 to 8, wherein the first electrode is a fixed electrode and the second electrode is a movable electrode.   The acceleration sensor which detects the acceleration which acted on the MEMS sensor by detecting the change of the electrostatic capacitance between the first electrode and the second electrode. The MEMS sensor as described.   The first electrode is driven in a direction toward and away from the recess, and an angular velocity acting on the MEMS sensor at the time of driving is detected as a change in capacitance between the first electrode and the second electrode. The MEMS sensor as described in any one of Claims 6-11 containing the angular velocity sensor detected by this. The MEMS sensor according to claim 6, wherein the base film is made of SiO ₂ .   The MEMS sensor according to claim 6, wherein the base film has a thickness of 2 μm to 5 μm.   The MEMS sensor as described in any one of Claims 6-14 whose thickness of the said polysilicon layer is 5 micrometers-20 micrometers. The MEMS sensor according to any one of claims 6 to 15,
And a resin package formed so as to cover the MEMS sensor.   The MEMS package according to claim 16, further comprising an integrated circuit electrically connected to the MEMS sensor and covered with the same resin package as the MEMS sensor. Further comprising a substrate having a front surface and a back surface and supporting the MEMS sensor on the front surface;
The MEMS package according to claim 16 or 17, wherein the resin package seals the MEMS sensor so as to cover the front surface of the substrate and to expose the back surface of the substrate.

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