JP2009270961A - Mems sensor and its method for manufacturign - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an MEMS (Micro Electro Mechanical Systems) sensor for simplifying the manufacturing process while achieving, on the surface side, the connection of wiring required for detecting physical quantity of the facing direction of a substrate and a cap, and its method for manufacturing. <P>SOLUTION: The flat cap 12 made of doped polysilicon is supported on a silicon substrate 2 in a facing state to the silicon substrate 2 via a second insulating layer 9 by a wall section 6 and separating section 7. A Z movable electrode 5 made of doped polysilicon is disposed between the silicon substrate 2 and the cap 12. The Z movable electrode 5 includes a surface disposed at a position lower toward the silicon substrate 2 side than the surfaces of the wall section 6 and separating section 7, is separated from the silicon substrate 2 and the cap 12, and can displace to the facing direction of the silicon substrate 2 and the cap 12. Thus, the cap 12 and the Z movable electrode 5 constitute a capacitor whose capacitance varies with variation of the interval between them. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sensor manufactured by MEMS (Micro Electro Mechanical Systems) technology and a manufacturing method thereof.

Recently, since the MEMS sensor has been mounted on a mobile phone, the attention of the MEMS sensor is rapidly increasing. As a typical MEMS sensor, for example, an acceleration sensor for detecting the acceleration of an object is known.
A conventional acceleration sensor is manufactured by bonding a cap made of glass or silicon to a processed SOI (Silicon On Insulator) substrate. Specifically, by selectively removing the SOI layer (silicon layer) that forms the surface layer of the SOI substrate and the insulating layer (silicon oxide layer) below the SOI layer, the base layer of the SOI layer (the lower layer of the insulating layer) A plurality of movable conductive portions floating from the silicon substrate and a plurality of fixed conductive portions fixed to the silicon substrate via an insulating layer are formed. Then, the cap is bonded onto the fixed conductive portion by an anodic bonding method, and an acceleration sensor is obtained.

The pair of the movable conductive portion and the fixed conductive portion facing each other in the X axis direction constitutes a capacitor for detecting acceleration in the X axis direction. Further, the pair of the movable conductive portion and the fixed conductive portion facing in the Y-axis direction constitutes a capacitor for detecting the acceleration in the Y-axis direction. When acceleration in the X-axis direction or the Y-axis direction occurs in the acceleration sensor (an object on which the acceleration sensor is mounted), the movable conductive portion is displaced, and the interval between the movable conductive portion and the fixed conductive portion changes. Along with this, the capacitance of the capacitor composed of the movable conductive portion and the fixed conductive portion changes. Therefore, the acceleration in the X-axis direction or the Y-axis direction can be detected based on the change in capacitance. Further, if a capacitor is constituted by the movable conductive portion and the silicon substrate, the acceleration in the facing direction (Z-axis direction) of the movable conductive portion and the silicon substrate can be detected.
JP 2007-150098 A

  However, in order to detect the acceleration in the Z-axis direction, it is necessary to electrically connect the wiring to the silicon substrate. In order to achieve the connection of the wiring on the surface side (the side where the cap is provided), a wiring connection pad is provided on the fixed conductive portion that is not used for detecting the acceleration in the X-axis direction and the Y-axis direction. In addition, it is necessary to provide a through electrode that continuously penetrates the fixed conductive portion and the insulating layer between the pad and the silicon substrate, which considerably complicates the manufacturing process of the acceleration sensor.

  Therefore, the object of the present invention is to achieve the connection of wiring necessary for detecting the physical quantity in the opposing direction between the substrate and the cap on the surface side (the side where the cap is provided) To provide a MEMS sensor and a method for manufacturing the same that can be simplified.

  According to a first aspect of the present invention for achieving the above object, there is provided a substrate, a conductive material, a support portion provided on the substrate, and a first insulation interposed between the substrate and the support portion. A flat cap that is made of a conductive material, is supported by the support through the second insulating layer and faces the substrate, and the support. Made of the same material as that of the support portion, formed in the same layer as the support portion, and has a surface thereof at a position lower than the surface of the support portion toward the substrate side, and is separated from the substrate and the cap. And a movable part that is displaceable in the opposing direction of the substrate and the cap.

  According to this configuration, the support portion made of the conductive material is provided on the substrate via the first insulating layer. A flat cap made of a conductive material is supported by the support portion in a state of facing the substrate. The support portion and the cap are insulated from each other by interposing the second insulating layer therebetween. And between the board | substrate and a cap, the movable part which is spaced apart from a board | substrate and a cap and consists of the same material as the material of a support part is provided. The movable portion is displaceable in a direction in which the substrate and the cap face each other (hereinafter referred to as “Z-axis direction” in this section). Thereby, a cap and a movable part comprise the capacitor | condenser from which an electrostatic capacitance changes with the changes of those space | intervals.

  When a physical quantity in the Z-axis direction occurs in the MEMS sensor (an object on which the MEMS sensor is mounted), or when a physical quantity in the Z-axis direction acts on the MEMS sensor and the movable part is displaced, the distance between the cap and the movable part changes. . Along with this, the capacitance of the capacitor including the cap and the movable portion changes, so that the physical quantity in the Z-axis direction can be detected based on the change in the capacitance. In addition, as a physical quantity, an acceleration, a sound pressure, etc. are illustrated.

And the movable part is formed in the same layer as the support part, and has the surface in the position which fell to the board | substrate side rather than the surface of the support part. As a result, a space larger than the thickness of the second insulating layer can be secured between the surface of the movable part and the cap, and when the movable part is displaced, the collision between the movable part and the cap is prevented. can do.
Further, in a capacitor composed of a cap and a movable part, the cap serves as a fixed electrode, and wiring connection to the fixed electrode is achieved by providing a wiring connection pad on the cap. Therefore, unlike the conventional acceleration sensor, there is no need to provide a through electrode for achieving connection between the substrate and the wiring. Therefore, the wiring process necessary for detecting the acceleration in the Z-axis direction can be achieved on the surface side, but the manufacturing process can be simplified as compared with the configuration of the conventional acceleration sensor.

  According to a second aspect of the present invention, there is provided a step of forming a conductive material layer on a substrate with a first insulating layer interposed therebetween, and for selectively exposing the conductive material layer on a surface of the conductive material layer. A step of forming a second insulating layer having an opening, a step of forming a recess by entirely digging a portion exposed from the opening in the conductive material layer, and a portion exposed from the opening in the conductive material layer. And removing the conductive material layer in a thickness direction to divide the conductive material layer to form a support portion and a movable portion including the divided portions of the conductive material layer; and the movable portion in the first insulating layer; A method of manufacturing a MEMS sensor, comprising: a step of selectively removing a contact portion; and a step of bonding a flat cap made of a conductive material on the second insulating layer.

By this manufacturing method, the MEMS sensor according to claim 1 can be manufactured.
The step of forming the concave portion includes a step of oxidizing a surface of a portion exposed from the opening in the conductive material layer and a step of removing the oxidized portion by etching, as described in claim 3. Also good. In this method, the difference in etching rate between the oxidized portion and the non-oxidized portion of the conductive material layer can be used to satisfactorily control the etching amount, and the concave portion can be reliably and easily formed in the conductive material layer. it can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of an acceleration sensor according to an embodiment of the present invention.
The acceleration sensor 1 is a sensor (MEMS sensor) manufactured by MEMS technology. The acceleration sensor 1 includes a silicon substrate 2 having a rectangular shape in plan view.
On the silicon substrate 2, a plurality of XY movable electrodes 3, a plurality of XY fixed electrodes 4 facing each XY movable electrode 3 with a space therebetween, and a Z movable electrode 5 are provided. The XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5 are made of, for example, polysilicon provided with conductivity by doping impurities at a high concentration (hereinafter, simply referred to as “doped polysilicon”). And have the same thickness.

  For example, the plurality of XY movable electrodes 3 are arranged at intervals in the X-axis direction parallel to the surface of the silicon substrate 2 and each extend in the Y-axis direction orthogonal to the X-axis direction, and Y A plurality of Y movable electrodes that are arranged at intervals in the axial direction and extend in the X-axis direction are included. One end portion of each X movable electrode in the Y-axis direction is connected by an X connection portion (not shown) extending in the X-axis direction. As a result, the X movable electrode and the X connecting portion have a comb-like structure. Further, one end portion of each Y movable electrode in the X axis direction is connected by a Y connecting portion (not shown) extending in the Y axis direction. Thereby, the Y movable electrode and the Y connecting portion have a comb-like structure.

  On the other hand, the plurality of XY fixed electrodes 4 are opposed to the respective X movable electrodes at intervals in the X-axis direction, and extend to the Y-axis direction, respectively. A plurality of Y fixed electrodes that are opposed to each other in the axial direction and that extend in the X-axis direction are included. One end portion of each X fixed electrode in the Y-axis direction is connected by an X connecting portion (not shown) extending in the X-axis direction. As a result, the X fixed electrode and the X coupling portion have a comb-like structure in which the comb movable teeth and the X coupling portion are engaged with each other without contacting each other. In addition, one end portion of each Y fixed electrode in the X-axis direction is connected by a Y connecting portion (not shown) extending in the Y-axis direction. As a result, the Y fixed electrode and the Y connecting portion have a comb-like structure in which the comb movable teeth and the Y connecting portion that are in a comb-like structure mesh with each other without contacting each other.

The Z movable electrode 5 is formed in a square shape in plan view.
In FIG. 1, the X movable electrode included in the XY movable electrode 3 and the X fixed electrode included in the XY fixed electrode 4 are shown with the direction orthogonal to the paper surface as the Y-axis direction. Illustration of the Y movable electrode included in the XY movable electrode 3 and the Y fixed electrode included in the XY fixed electrode 4 is omitted.

On the silicon substrate 2, a square-shaped wall portion 6 having a square shape in plan view along the periphery of the silicon substrate 2 is provided. In the region surrounded by the wall portion 6, the XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5 are provided separately from the wall portion 6.
Further, on the silicon substrate 2, two separation portions 7 are provided separately from the XY movable electrode 3, the XY fixed electrode 4, the Z movable electrode 5, and the wall portion 6 in a region surrounded by the wall portion 6. Yes.

  The wall portion 6 and the separation portion 7 are made of the same material as that of the XY movable electrode 3, the XY fixed electrode 4 and the Z movable electrode 5, for example, doped polysilicon. The wall portion 6 and the separation portion 7 are formed in the same layer as the XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5, and are thicker than the thicknesses of the XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5. Each surface has a large thickness and is disposed at a position one level higher than each surface of the XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5. In other words, the XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5 have their respective surfaces at positions lower than the surfaces of the wall portion 6 and the separation portion 7 on the silicon substrate 2 side.

A first insulating layer 8 is interposed between each of the silicon substrate 2 and the wall portion 6 and the separation portion 7. The first insulating layer 8 is made of, for example, silicon oxide.
The X connecting portion that connects the X movable electrodes and the Y connecting portion that connects the Y movable electrodes are connected to the inner surface of the wall portion 6. Thereby, the XY movable electrode 3 is electrically connected to the wall portion 6 via the X coupling portion or the Y coupling portion. Further, the first insulating layer 8 is not interposed between the silicon substrate 2 and the XY movable electrode 3, and the XY movable electrode 3 is floated on the silicon substrate 2, and is connected to the X connection portion or the Y connection. It is cantilevered by the part, and can be displaced in the facing direction with the XY fixed electrodes 4 facing each other.

The X coupling portion that couples the X fixed electrodes is connected to the side surface of one separation portion 7 (hereinafter referred to as “X separation portion 7”). Accordingly, the X fixed electrode (XY fixed electrode 4) is electrically connected to the X separation unit 7 via the X coupling unit.
The Y connecting portion that connects the Y fixed electrodes is connected to the side surface of another one separating portion 7 (hereinafter referred to as “Y separating portion 7”). Thereby, the Y fixed electrode (XY fixed electrode 4) is electrically connected to the Y separating portion 7 via the Y connecting portion.

  A connecting portion (not shown) is integrally formed on the Z movable electrode 5, and this connecting portion is connected to the inner side surface of the wall portion 6. Thereby, the Z movable electrode 5 is electrically connected to the wall part 6 (at the same potential) via the connection part. Further, the first insulating layer 8 is not interposed between the silicon substrate 2 and the Z movable electrode 5, and the Z movable electrode 5 is floated on the silicon substrate 2 and is connected to the X axis by the connecting portion. It is supported so that it can be displaced in the Z-axis direction orthogonal to the direction and the Y-axis direction.

  A second insulating layer 9 is provided on the wall portion 6 and each separation portion 7. Specifically, on the wall portion 6, the second insulating layer 9 is formed in a square shape in plan view corresponding to the inner peripheral shape along the inner periphery of the wall portion 6. On each isolation | separation part 7, the 2nd insulating layer 9 is formed in the pattern which has the opening 9a which exposes the surface of the isolation | separation part 7 selectively. The second insulating layer 9 has, for example, a two-layer structure in which a silicon oxide layer and a silicon nitride layer are stacked in this order.

A grounding pad 10 is provided on the surface of the wall portion 6 at a portion exposed from the second insulating layer 9. Further, a voltage application pad 11 is provided in a portion exposed from the opening 9 a on the surface of each separation portion 7. The grounding pad 10 and the voltage applying pad 11 are made of, for example, aluminum.
A flat cap 12 is supported on the second insulating layer 9. The cap 12 has an outer shape (a square shape in plan view) corresponding to the shape of the second insulating layer 9 on the wall portion 6 so as to cover a region surrounded by the second insulating layer 9 on the wall portion 6 from above. Is provided. Thereby, the space in which the XY movable electrode 3, the XY fixed electrode 4, the Z movable electrode 5, and the separation portion 7 are arranged is a space sealed by the silicon substrate 2, the wall portion 6, the second insulating layer 9, and the cap 12 ( A vacuum space or a space filled with an inert gas such as nitrogen gas), and entry of moisture or the like from the outside into this space is prevented. The cap 12 has an opening 12 a for exposing the voltage application pad 11 on each separation portion 7. The cap 12 is made of doped polysilicon, for example.

A voltage application pad 13 is provided on the surface of the cap 12. The voltage application pad 13 is made of aluminum, for example.
A wiring (not shown) controlled to the ground potential (0 V) is connected to the grounding pad 10 through the opening 12a. Each voltage application pad 11, 13 is connected to a wiring (not shown) controlled to a constant potential (for example, ± 5 V).

  Accordingly, a constant voltage is applied between the XY movable electrode 3 and the XY fixed electrode 4 facing each other between the XY movable electrode 3 and the XY fixed electrode 4, and the capacitance changes due to the change in the interval. Consists of a capacitor. Further, the Z movable electrode 5 and the cap 12 constitute a capacitor in which a constant voltage is applied between them and the capacitance changes due to a change in the interval.

  When acceleration in the X-axis direction occurs in the acceleration sensor 1 (the object on which the acceleration sensor 1 is mounted) and each X movable electrode (XY movable electrode 3) is displaced in the X-axis direction, the X movable electrode and the X fixed electrode that face each other. The capacitance of each capacitor formed of (XY fixed electrode 4) changes. As the capacitance changes, the wiring connected to the X movable electrode through the wall 6 and the grounding pad 10 and the X fixed electrode through the X separating unit 7 and the voltage applying pad 11 are electrically connected. A current corresponding to the amount of change in the capacitance flows through a circuit including the wiring connected to. Accordingly, the acceleration in the X-axis direction generated in the acceleration sensor 1 can be detected based on the current.

  When acceleration in the Y-axis direction is generated in the acceleration sensor 1 and each Y movable electrode (XY movable electrode 3) is displaced in the Y-axis direction, each capacitor composed of a Y movable electrode and a Y fixed electrode (XY fixed electrode 4) facing each other. The capacitance of changes. As the capacitance changes, the wiring connected to the Y movable electrode via the wall 6 and the grounding pad 10 is electrically connected to the Y fixed electrode via the Y separating portion 7 and the voltage applying pad 11. A current corresponding to the amount of change in the capacitance flows through a circuit including the wiring connected to. Therefore, the acceleration in the Y-axis direction generated in the acceleration sensor 1 can be detected based on the current.

  Further, when acceleration in the Z-axis direction occurs in the acceleration sensor 1, the Z movable electrode 5 is displaced in the Z-axis direction, and the capacitance of the capacitor formed by the Z movable electrode 5 and the cap 12 changes. As the capacitance changes, the wiring connected to the Z movable electrode 5 via the wall 6 and the grounding pad 10 and the wiring electrically connected to the cap 12 via the voltage application pad 13 A current corresponding to the amount of change in capacitance flows through a circuit including Therefore, the acceleration in the Z-axis direction generated in the acceleration sensor 1 can be detected based on the current.

2A to 2I are schematic cross-sectional views in each manufacturing process of the acceleration sensor shown in FIG.
In the manufacturing process of the acceleration sensor 1, first, as shown in FIG. 2A, a silicon oxide layer 21 is formed on the surface of the silicon substrate 2 by PECVD (Plasma Enhanced Chemical Vapor Deposition) method. The silicon oxide layer 21 is formed to a thickness of 5 μm, for example. Thereafter, a doped polysilicon layer 22 is formed on the silicon oxide layer 21 by epitaxial growth or LPCVD (Low Pressure Chemical Vapor Deposition). The doped polysilicon layer 22 is formed to a thickness of 25 μm, for example. After the formation of the doped polysilicon layer 22, the doped polysilicon layer 22 is subjected to hydrogen annealing for 10 minutes, for example, under conditions of a temperature of 1000 ° C. and a pressure of 10 Torr.

  Next, as shown in FIG. 2B, silicon oxide and silicon nitride are deposited in this order on the doped polysilicon layer 22 by LOPOS (Local Oxidation of Poly silicon Over Silicon) technology. An insulating layer 23 made of is formed. Thereafter, the insulating layer 23 is selectively removed by photolithography and etching, and a pattern of the insulating layer 23 having an opening 23a is formed in a portion where the XY movable electrode 3, the XY fixed electrode 4, and the Z movable electrode 5 are to be formed. Is done.

Thereafter, as shown in FIG. 2C, a portion of the doped polysilicon layer 22 exposed from the opening 23a of the insulating layer 23 is oxidized, and an oxide film 24 is formed in that portion.
Next, as shown in FIG. 2D, the oxide film 24 is removed by etching. As a result, a recess 25 communicating with the opening 23 a of the insulating layer 23 is formed in the doped polysilicon layer 22.

  Thereafter, the doped polysilicon layer 22 is patterned by photolithography and etching. Specifically, a portion of the doped polysilicon layer 22 exposed from the opening 23a of the insulating layer 23 is selectively removed over the thickness direction, so that the doped polysilicon layer 22 is divided. Thereby, as shown in FIG. 2E, on the silicon oxide layer 21, the XY movable electrode 3, the XY fixed electrode 4, the Z movable electrode 5, the wall portion 6 and the separation portion which are each divided portions of the doped polysilicon layer 22 are formed. 7 is formed.

Next, as shown in FIG. 2F, the insulating layer 23 is selectively removed (patterned) by photolithography and etching, and the second insulating layer 9 having the opening 9a is formed on the wall portion 6 and the separation portion 7. Is done.
Thereafter, as shown in FIG. 2G, the silicon oxide layer 21 is selectively removed from below the XY movable electrode 3 and the Z movable electrode 5 by dry etching. Thereby, the XY movable electrode 3 and the Z movable electrode 5 are floated from the surface of the silicon substrate 2 and can be displaced respectively. Further, the silicon oxide layer 21 remains below the wall portion 6 and the separation portion 7 and becomes the first insulating layer 8 that supports them.

Next, as shown in FIG. 2H, a cap 12 having an opening 12a is attached on the second insulating layer 9 by anodic bonding.
Thereafter, an aluminum film is formed on the surfaces of the wall portion 6, the separation portion 7, and the cap 12 by sputtering. Then, the aluminum film is patterned by photolithography and etching, and the aluminum film is selectively left on the wall portion 6, the separation portion 7, and the cap 12. As a result, as shown in FIG. 2I, the grounding pad 10, the voltage application pad 11, and the voltage application pad 13 are formed on the wall part 6, the separation part 7, and the cap 12, respectively.

Thereafter, the back surface of the silicon substrate 2 is ground and the silicon substrate 2 is thinned, whereby the acceleration sensor 1 shown in FIG. 1 is obtained.
As described above, the wall 6 and the isolation 7 made of doped polysilicon are provided on the silicon substrate 2 via the first insulating layer 8. The wall portion 6 and the separation portion 7 support a flat cap 12 made of doped polysilicon in a state of facing the silicon substrate 2. The wall portion 6 and the separation portion 7 and the cap 12 are insulated from each other by the second insulating layer 9 interposed therebetween. Between the silicon substrate 2 and the cap 12, a Z movable electrode 5 made of the same material as that of the wall portion 6 and the separation portion 7 is provided apart from the silicon substrate 2 and the cap 12. The Z movable electrode 5 can be displaced in the facing direction (Z axis direction) of the silicon substrate 2 and the cap 12. Thereby, the cap 12 and the Z movable electrode 5 constitute a capacitor whose electrostatic capacity changes due to a change in the distance between them. The acceleration in the Z-axis direction can be detected based on the change in the capacitance of the capacitor.

  The Z movable electrode 5 is formed in the same layer as the wall portion 6 and the separation portion 7, and has the surface thereof at a position lower than the surfaces of the wall portion 6 and the separation portion 7 toward the silicon substrate 2. Thereby, a space having a larger interval than the thickness of the second insulating layer 9 can be secured between the surface of the Z movable electrode 5 and the cap 12, and when the Z movable electrode 5 is displaced, the Z movable electrode 5 and the cap 12 can be prevented from colliding with each other.

  Further, in the capacitor composed of the cap 12 and the Z movable electrode 5, the cap 12 serves as a fixed electrode, and connection of wiring to the fixed electrode is achieved by providing a voltage application pad 13 on the cap 12. Therefore, unlike the conventional acceleration sensor, there is no need to provide a through electrode for achieving connection between the silicon substrate 2 and the wiring. Therefore, the wiring process necessary for detecting the acceleration in the Z-axis direction can be achieved on the surface side, but the manufacturing process can be simplified as compared with the configuration of the conventional acceleration sensor.

  In the manufacturing process, a portion of the doped polysilicon layer 22 exposed from the opening 23a of the insulating layer 23 is oxidized, and the oxide film 24 formed by the oxidation is removed, whereby the doped polysilicon layer 22 is removed. A recess 25 is formed on the surface. In this method, the difference in etching rate between the doped polysilicon layer 22 and the oxide film 24 can be used to satisfactorily control the etching amount, and the recess 25 can be reliably and easily formed in the doped polysilicon layer 22. Can be formed.

Although one embodiment of the present invention has been described above, the present invention can be implemented in other forms. For example, although an acceleration sensor for detecting the acceleration of an object has been taken up as an example of a MEMS sensor, the present invention is not limited to an acceleration sensor, and can also be applied to a pressure sensor that detects sound pressure.
In addition, various design changes can be made within the scope of matters described in the claims.

FIG. 1 is a schematic cross-sectional view of an acceleration sensor according to an embodiment of the present invention. 2A is a schematic cross-sectional view for explaining a method of manufacturing the acceleration sensor shown in FIG. FIG. 2B is a cross-sectional view schematically showing a step subsequent to FIG. 2A. FIG. 2C is a cross-sectional view schematically showing a step subsequent to FIG. 2B. FIG. 2D is a cross-sectional view schematically showing a step subsequent to FIG. 2C. FIG. 2E is a cross-sectional view schematically showing a step subsequent to FIG. 2D. 2F is a cross-sectional view schematically showing a step subsequent to FIG. 2E. FIG. 2G is a cross-sectional view schematically showing a step subsequent to FIG. 2F. FIG. 2H is a cross-sectional view schematically showing a step subsequent to FIG. 2G. FIG. 2I is a cross-sectional view schematically showing a step subsequent to FIG. 2H.

Explanation of symbols

1 Acceleration sensor (MEMS sensor)
2 Silicon substrate (substrate)
5 Z movable electrode (movable part)
6 Wall (supporting part)
7 Separation part (support part)
8 First insulating layer 9 Second insulating layer 12 Cap 21 Silicon oxide layer (first insulating layer)
22 doped polysilicon layer (conductive material layer)
23 Insulating layer (second insulating layer)
23a Opening 24 Oxide film (oxidized part)
25 recess

Claims (3)

A substrate,
A support made of a conductive material and provided on the substrate;
A first insulating layer interposed between the substrate and the support;
A second insulating layer provided on the support;
A plate-like cap made of a conductive material, supported by the support through the second insulating layer, and facing the substrate;
It is made of the same material as the material of the support part, is formed in the same layer as the support part, has its surface at a position lower than the surface of the support part toward the substrate side, and the substrate and the cap A MEMS sensor, comprising: a movable part that is spaced apart from the substrate and that is displaceable in a direction opposite to the substrate and the cap. Forming a conductive material layer on the substrate across the first insulating layer;
Forming a second insulating layer having an opening for selectively exposing the conductive material layer on a surface of the conductive material layer;
Forming a recess by digging up the entire portion exposed from the opening in the conductive material layer; and
By selectively removing a portion of the conductive material layer exposed from the opening over the thickness direction, the conductive material layer is divided to form a support portion and a movable portion including the divided portions of the conductive material layer. Process,
Selectively removing a portion of the first insulating layer in contact with the movable portion;
And a step of joining a flat cap made of a conductive material on the second insulating layer.   3. The manufacturing of the MEMS sensor according to claim 2, wherein the step of forming the concave portion includes a step of oxidizing a surface of a portion exposed from the opening in the conductive material layer and a step of removing the oxidized portion by etching. Method.

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