JP2010245461A - Manufacturing method of mems sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an MEMS sensor especially capable of lowering the maximum peeling stress by dispersing peeling stress. <P>SOLUTION: A recessed part 11 with bottom is formed on a front surface 10a side of a first silicon substrate 10, wherein a retreating region 14a, retreating from an opening side edge part 11a toward a bottom face 11b direction of the recessed part 11 in the direction of spreading a width dimension of the recessed part 11, is provided to a sidewall 14 of the recessed part 11. Continuously, an oxide insulating layer is formed on at least one of the surface of the first silicon substrate 10 and the surface of a second substrate. Continuously, the surface of the first silicon substrate 10 and the surface of the second silicon substrate are bonded together to make the recessed part 11 into a closed space, and in this state, heat treatment is performed. By providing the retreating region 14a on the bonding side of the sidewall 14 to the second silicon substrate, the peeling stress applied to the vicinity of the edge part of the recessed part 11 when the heat treatment is performed can be dispersed to lower the maximum peeling stress. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a MEMS sensor having a heat treatment process in a state where a closed space surrounded by a first substrate and a second substrate exists.

FIG. 15 is a cross-sectional view showing an example of a conventional MEMS sensor manufacturing process. In FIG. 15A, a plurality of bottomed recesses 2 are formed on the surface 1a of the first silicon substrate 1 by dry etching or the like. In FIG. 15B, the surface 4a of the second silicon substrate 4 having the oxide insulating layer (SiO ₂ layer) 3 formed on the surface by thermal oxidation and the surface 1a of the first substrate 1 are joined at room temperature. Thereafter, heat treatment is performed to increase the bonding strength. In the step shown in FIG. 15C, the shape of the exposed surface and side surface of the first silicon substrate 1 is adjusted by an etching or polishing process, and the movable part is further positioned at the position where the recess 2 of the first silicon substrate 1 is formed. And a sensor part (not shown) separated into a fixed part.

JP 2007-322149 A

  When heat treatment is performed in the step shown in FIG. 15B, oxygen is dispersed in the silicon substrate from a bonded state in which Si atoms are bonded via oxygen at the bonding interface between the first silicon substrate 1 and the second silicon substrate 4. As a result, bonding between Si atoms is performed, whereby the bonding strength between the first silicon substrate 1 and the second silicon substrate 4 can be effectively improved.

  In the MEMS sensor manufacturing method shown in FIG. 15, the recess 2 formed in the first silicon substrate 1 in the step of FIG. 15B is closed by the first silicon substrate 1 and the second silicon substrate 4. It becomes space.

  At this time, when the heat treatment for improving the bonding strength is performed, the oxide insulating layer 3 in the recess 2 formed in the first silicon substrate 1 shown in FIG. It was found that a very strong peeling stress was applied in the vicinity of the side joining surface side edge 2a. In particular, this peeling stress is caused by the corner 2b of the joint surface side edge 2a of the recess 2 as shown by the arrow in FIG. 16B (partial plan view of the recess, where the periphery of the recess is indicated by hatching). Experiments to be described later show that it is the strongest in the vicinity.

  Therefore, the present invention solves the above-described conventional problems, and in particular, an object of the present invention is to provide a method for manufacturing a MEMS sensor capable of dispersing peeling stress and reducing the maximum peeling stress.

The manufacturing method of the MEMS sensor in the present invention is as follows:
(A) A bottomed recess is formed on the surface side of the first substrate, and at this time, the recess recedes from the opening side edge toward the bottom surface of the recess in the direction of increasing the width dimension of the recess. Providing a receding region to perform,
(B) forming an oxide insulating layer on at least one of the surface of the first substrate or the surface of the second substrate;
(C) joining the surface of the first substrate and the surface of the second substrate, and performing a heat treatment in a state where the concave portion is a closed space;
It is characterized by having.

  As described above, when the heat treatment is performed in the step (c), the peeling stress applied to the vicinity of the edge portion (open side edge portion in the step (a)) that is closed by the bonding with the second substrate of the concave portion. It can be dispersed and the maximum peel stress can be reduced.

  In the present invention, it is preferable that in the step (a), the receding region is formed so that the width dimension of the concave portion gradually increases from the opening side edge portion to the middle position in the bottom surface direction.

In the present invention, after the step (c),
(D) processing one of the first substrate or the second substrate at the position of the recess formed in the first substrate to form a sensor unit separated into a movable part and a fixed part;
It is possible to have Thereby, a desired physical quantity sensor can be manufactured.

  According to the method for manufacturing a MEMS sensor of the present invention, it is possible to disperse the peeling stress applied to the vicinity of the edge on the side that is closed by bonding with the second substrate of the recess when heat treatment is performed, and to reduce the maximum peeling stress.

Process drawing (longitudinal sectional view) showing a manufacturing method of the MEMS sensor in the present embodiment, An enlarged longitudinal sectional view showing a manufacturing process when forming the recess shown in FIG. (A) is an enlarged vertical sectional view of a part of FIG. 1 (b), and (b) shows the peeling stress applied to the vicinity of the edge (opening side edge) of the recess that is closed by the second silicon substrate. A plan view of a recess for explanation; A longitudinal sectional view of the vicinity of the recess in another embodiment, The top view of the acceleration sensor of this embodiment, FIG. 5 is a longitudinal sectional view of the acceleration sensor cut in the height direction from the line AA in FIG. FIG. 6 is a partially enlarged longitudinal sectional view showing the vicinity of the anchor portion 37 in FIG. 6; Process drawing (longitudinal sectional view) showing a method for manufacturing the acceleration sensor of the present embodiment, Process drawing (longitudinal sectional view) showing a method of manufacturing an acceleration sensor of another embodiment, Partially enlarged vertical sectional view showing the vicinity of the sticking prevention part in an enlarged manner, A graph showing the relationship between the volume of the recess (closed space) and the internal stress at normal temperature and during heat treatment, Schematic diagram of the MEMS sensor used in the experiment, FIG. 12 is a graph showing the distribution of peel stress when the MEMS sensor in FIG. 12 is heat-treated and the radius of curvature of the R portion is changed; A graph showing the relationship between the radius of curvature of the R part and the maximum peel stress; Process drawing (longitudinal sectional view) showing a conventional method for manufacturing a MEMS sensor, FIG. 15A is an enlarged vertical sectional view of a part of FIG. 15B, and FIG. 15B shows the peeling stress applied to the vicinity of the edge (opening side edge) of the recess that is closed by the second silicon substrate. A plan view of a recess for explanation;

  FIG. 1 is a process diagram showing a method for manufacturing a MEMS sensor according to this embodiment. Each process drawing of FIG. 1 is shown by the longitudinal cross-sectional view cut | disconnected and shown from the thickness direction. FIG. 2 is an enlarged longitudinal sectional view showing a manufacturing process when forming the concave portion shown in FIG. FIG. 3A is an enlarged longitudinal sectional view of a part of FIG. 1B, and FIG. 3B is a portion near the edge (opening edge) of the recess that is closed by the second silicon substrate. It is a top view of the recessed part for demonstrating the peeling stress to apply. FIG. 4 is a vertical cross-sectional view of the vicinity of a recess according to another embodiment.

  In the step of FIG. 1A, a plurality of bottomed recesses 11 are formed on the surface 10a of the first silicon substrate 10 made of silicon constituting the MEMS sensor by dry etching or the like.

As shown in FIG. 2A, a mask 13 having an opening 12 is provided on the surface 10 a of the first silicon substrate 10. 2B, the surface 10a of the first silicon substrate 10 exposed from the opening 12 of the mask 13 is dried using, for example, SF ₆ gas, C ₄ F ₈ gas, and O ₂ gas. The bottomed recess 11 is formed by etching. In the step shown in FIG. 2B, not only the portion directly under the opening 12 but also the first silicon substrate 10 under the mask 13 around the opening 12 is removed by etching. Therefore, the opening width T1 of the recess 11 is slightly larger than the opening width T2 of the opening 12 of the mask 13. Further, as shown in FIG. 2B, a receding region 14a is formed on the side wall 14 of the recess 11 so as to recede in the direction of increasing the width of the recess 11 from the opening side edge 11a of the recess 11 toward the bottom surface 11b. The In addition, below, the code | symbol 11a may be described with the joint surface side edge part 11a.

  Further, in this embodiment, the receding region 14a is formed from the opening side edge portion 11a to the middle position 11c in the direction of the bottom surface 11b, and the width dimension of the concave portion 11 gradually decreases from the middle position 11c toward the bottom surface 11b. A skirt region 14b that is inclined in the direction is formed. In FIG. 2B, the width dimension T3 is clearly shown at the position of the largest width dimension of the recess 11.

As shown in FIG. 2B, the side wall 14 of the recess 11 has a curved shape that is generally depressed. In order to obtain such a shape, the flow rate of SF ₆ gas, the flow rate of C ₄ F ₈ gas, the flow rate of O ₂ gas, the opening width T ₂ of the opening 12 of the mask 13, and the etching depth are adjusted. As an example, the flow rate of the SF ₆ gas, 500 sccm, the flow rate of C ₄ F ₈ gas, about 180 sccm, 200 sccm about the flow rate of O ₂ gas, 500 [mu] m about the opening width T2 of the opening 12 of the mask 13, the etching depth Is about 1.0 μm. As an example of a comparative example in which no receding region is formed as compared with the present embodiment, SF ₆ gas is 350 sccm, C ₄ F ₈ gas is 150 sccm, and O ₂ gas is 0 sccm. 1 sccm = 1.667 × 10 ⁻⁸ (m ³ / sec) (normalized at 25 ° C.).

  Then, in the step of FIG. 2C, the mask 13 is removed. Here, the opening width T1 of the recess 11 is about 501 to 502 μm, the maximum width dimension T3 in the recess 11 is about 503 to 505 μm, the width dimension T4 of the bottom surface 11b is about 500 μm, and the depth dimension T5 of the recess 11 is It is about 1.0-2.0 micrometers.

Next, in the step shown in FIG. 1B, a second silicon substrate 20 is prepared, and an oxide insulating layer 21 (SiO ₂ layer) is formed on the entire surface 20a of the second silicon substrate 20 by thermal oxidation.

  Next, the surface 10a of the first silicon substrate 10 and the surface 20a of the second silicon substrate 20 are opposed to each other at room temperature. The room temperature bonding can also bond the first silicon substrate 10 and the second silicon substrate 20 strongly to some extent, but heat treatment is performed to obtain a stronger bonding strength. When heat treatment is performed, oxygen is dispersed in the silicon substrate from the bonded state in which the Si atoms are bonded via oxygen at the bonding interface between the first silicon substrate 10 and the second silicon substrate 20, thereby forming an Si interatomic bond. Thus, the bonding strength between the first silicon substrate 10 and the second silicon substrate 20 can be effectively improved.

  As shown in FIG. 1B, the recess 11 is heat-treated in a closed space surrounded by the first silicon substrate 10 and the second silicon substrate 20. The heat treatment temperature is about 1000 to 1100 ° C. As a result, the internal pressure of the recess 11 that is a closed space rises as compared with the normal temperature based on the ideal gas equation of state (PV = nRT), but is at most several times as large as that at the normal temperature. On the other hand, considering the stress, as shown in FIG. 3A, the joint surface side edge portion (opening side edge portion) of the concave portion 11 that is blocked by the surface 20a of the second silicon substrate 20 (surface of the oxide insulating layer 21). ) A peeling stress acts near 11a. In the present embodiment, as shown in FIG. 3A, the width dimension of the concave portion 11 is increased from the bonding surface side edge portion 11a closed by the second silicon substrate 20 on the side wall 14 of the concave portion 11 toward the bottom surface 11b. A receding region 14a that recedes in the expanding direction is provided. As a result, as shown in FIG. 3B (note that the periphery of the recess 11 is indicated by hatching), the peeling stress (indicated by an arrow) can be distributed over a wide range in the vicinity of the joining surface side edge portion 11a. It becomes possible to reduce peeling stress.

  Although the shape of the joint surface side edge (opening side edge) 11a of the recess 11 is not limited, in the present embodiment, the corner portion 11d is formed in the joint surface side edge (opening side edge) 11a. Is particularly effective. 11 d of corner | angular parts are parts which connect between adjacent joint surface side edge parts (opening side edge part) 11a. In FIG. 3B, the joint surface side edge (opening side edge) 11a connected via the corner 11d is shown linearly, but the joint surface side edge (opening side edge) 11a is a curved surface. It may be. At this time, the radius of curvature of the corner portion 11d is smaller than the radius of curvature of the joint surface side edge (opening side edge) 11a. As shown in the experimental results to be described later, the maximum peel stress is likely to be applied near the corner, but in the past, this maximum peel stress was very strong, whereas in this embodiment, the maximum peel stress was effectively reduced. It becomes possible to do.

  In another embodiment shown in FIG. 4, an R portion 25 as a receding region is formed between the side wall 26 of the concave portion 11 and the joint surface side edge portion 11 a. In the drawing, the side wall 26 extends linearly in the height direction, but may be inclined slightly. Further, the receding region may be formed over the entire side wall from the joining surface side edge portion 11a to the bottom surface 11b. In such a case, the longitudinal section of the recess 11 is substantially trapezoidal.

  In the step shown in FIG. 1C, the shape of the exposed surface and side surfaces of the first silicon substrate 10 is adjusted by an etching or polishing process. Thereafter, a sensor part separated into a movable part and a fixed part is formed at a position where the concave part 11 of the first silicon substrate 10 is formed.

For example, the acceleration sensor shown in FIGS. 5 and 6 can be manufactured by the manufacturing method of the present embodiment.
FIG. 5 shows the acceleration sensor of this embodiment, and is a plan view showing a movable part, a fixed part, and a frame layer. 6 is a cross-sectional view showing the overall structure of the acceleration sensor, and corresponds to a cross-sectional view taken along line AA in FIG.

  As shown in FIG. 6, the acceleration sensor includes a first silicon substrate 30, a second silicon substrate 31, and an oxide insulating layer 32 interposed between the first silicon substrate 30 and the second silicon substrate 31. Configured.

  On the second silicon substrate 31, a first fixed portion 33, a second fixed portion 34, a movable portion 35, and a frame layer 36 are formed separately. The first fixed portion 33, the second fixed portion 34, and the movable portion 35 constitute a sensor unit.

  As shown in FIG. 5, a square anchor portion 37 is connected to the first fixing portion 33. As shown in FIG. 6, the anchor portion 37 is fixedly supported on the surface of the first silicon substrate 30 by the oxide insulating layer 32. In addition, a square anchor portion 38 is connected to the second fixing portion 34. The anchor portion 38 is also fixedly supported on the surface of the first silicon substrate 30 by the oxide insulating layer 32.

  As shown in FIG. 5, a plurality of comb-like counter electrodes are formed on the fixing portions 33 and 44, respectively.

  In the acceleration sensor shown in FIG. 5, the inside of the rectangular frame layer 36 is a movable region, and in the movable region, the first fixed portion 33, the second fixed portion 34, and the anchor portions 37, 38, 39, A portion excluding 43 is defined as the movable portion 35.

  The movable portion 35 is supported by the first silicon substrate 30 via the oxide insulating layer 32 at the positions of the anchor portions 39 and 43 (see FIG. 6).

  Further, as shown in FIG. 5, the movable portion 35 is provided with a comb-like movable counter electrode positioned between the counter electrodes of the fixed portions 33 and 34.

  When acceleration acts on the acceleration sensor, the movable part moves due to the reaction. At this time, the capacitance changes due to the change in the facing distance between each movable counter electrode and the fixed counter electrode, and the change in the capacitance is detected by an electric circuit. The size can be detected.

  As shown in FIG. 6, a bottomed recess 40 is provided between the movable part and the fixed part and the first silicon substrate 30.

  FIG. 7 is an enlarged vertical sectional view in which the vicinity of the anchor portion 37 in FIG. 6 is enlarged. As shown in FIG. 6, a receding region 42 that recedes in the direction of increasing the width dimension of the concave portion 40 from the opening side edge portion 40 a toward the bottom surface 40 b is formed on the side wall 41 of the concave portion 40.

A method for manufacturing the acceleration sensor shown in FIGS. 5 to 7 will be described with reference to FIGS.
As shown in FIG. 8A, a recess 40 is formed in the surface 30 a of the first silicon substrate 30. The recess 40 is formed by a manufacturing method similar to that described with reference to FIG. Thereby, the retreat area | region 42 which recedes in the direction which expands the width dimension of the recessed part 40 from the opening side edge part 40a of the side wall 41 of the recessed part 40 to the middle of the bottom face 40b can be formed (refer FIG. 7).

Next, in the step of FIG. 8B, the surface 30a of the first silicon substrate 30 is thermally oxidized to form an oxide insulating layer 32 (SiO ₂ layer). Thereby, the oxide insulating layer 32 is also formed from the side wall 41 to the bottom surface 40 b of the recess 40. At this time, a receding region is formed along the receding region 42 on the surface of the portion of the oxide insulating layer 32 formed on the receding region 42 of the recess 40. In FIG. 1, the oxide insulating layer 21 is formed on the second silicon substrate 20 side, but in this embodiment, the oxide insulating layer 32 is formed on the first silicon substrate 30 side.

  Next, in the step shown in FIG. 8C, the surface of the first silicon substrate 30 and the surface of the second silicon substrate 31 are bonded at room temperature. At this time, the recess 40 becomes a closed space surrounded by the first silicon substrate 30 and the second silicon substrate 31. Then, heat treatment is performed to increase the bonding strength.

  In the present embodiment, the receding region 42 is formed on the bonding surface side edge (opening side edge) 40a side of the side wall 41 of the recess 40, and the receding region is also formed in the oxide insulating layer 32 accordingly. The peeling stress applied to the vicinity of the joining surface side edge portion 32a of the oxide insulating layer 32 (see FIG. 8C) can be dispersed, and the maximum peeling stress can be reduced.

  8D, deep RIE (Deep RIE) is used to attach the movable portion 35, the fixed portions 33, 34, the anchor portions 37, 38, 39, 43 to the second silicon substrate 31. Forms the frame layer 36. At this time, the movable portion 35 and the fixed portions 33 and 34 are formed at positions facing the recess 40 formed in the first silicon substrate 30.

  Next, in the step shown in FIG. 8E, the other oxide insulating layers 32 are formed by leaving the anchor portions 37, 38, 39, 43 and the oxide insulating layer 32 between the frame layer 36 and the first silicon substrate 30. It is removed in an isotropic etching process by wet etching or dry etching.

  However, if the moving space of the movable part 35 can be secured with a sufficient size between the movable part 35 and the first silicon substrate 30 by the recess 40, the oxide insulating layer 32 can be removed in the process of FIG. Also good. That is, the process of FIG. 8D can be completed without performing the process of FIG.

FIG. 9 is a longitudinal sectional view showing a method of manufacturing a MEMS sensor according to another embodiment.
First, in the step shown in FIG. 9A, a plurality of recesses 46 are formed by etching on the surface 45a of the first silicon substrate 45 facing downward in the figure. A convex portion sandwiched between the concave portions 46 and 46 is a sticking preventing portion 55.

  In the process of FIG. 9A, the recess 46 is formed by etching using the same manufacturing method as in FIG. As a result, as shown in FIG. 10, a receding region 48 that recedes in the direction of increasing the width dimension of the recess 46 is formed on the side wall 47 of the recess 46 from the opening side edge 46a to the middle of the bottom surface 46b.

  Next, in the step of FIG. 9B, the surface of the first silicon substrate 45 is thermally oxidized to form an oxide insulating layer 49. At this time, a receding region is formed on the surface of the oxide insulating layer 49 at a portion formed on the receding region 48 of the recess 46, following the receding region 48.

  Next, in the step shown in FIG. 9C, the surface of the first silicon substrate 45 and the surface of the second silicon substrate 50 are bonded at room temperature. At this time, as shown in FIG. 9C, the recess 46 becomes a closed space surrounded by the first silicon substrate 45 and the second silicon substrate 50. Then, heat treatment is performed to increase the bonding strength between the first silicon substrate 45 and the second silicon substrate 50. In the present embodiment, the receding region 48 is formed on the bonding surface side edge (opening side edge) 46a side of the side wall 47 of the recess 46, and the receding region is also formed in the oxide insulating layer 49 accordingly. The peeling stress applied to the vicinity of the bonding surface side edge portion 49a of the oxide insulating layer 49 (see FIG. 9C) can be dispersed, and the maximum peeling stress can be reduced.

  In the step of FIG. 9C, the upper surface of the first silicon substrate 45 is ground to a predetermined thickness.

  Subsequently, in the step shown in FIG. 9D, the first silicon substrate 45 is separated into a movable part 52 and a fixed part 53 constituting the sensor part 51 by using deep RIE (Deep RIE). In this embodiment, the first silicon substrate 45 around the sensor unit 51 is left as the frame body 54.

  9D, the oxide insulating layer 49 between the sensor unit 51 and the second silicon substrate 50 is removed by an isotropic etching process using wet etching or dry etching. In FIG. 9D, the oxide insulating layer 3 to be removed is indicated by a dotted line.

  At this time, convex sticking preventing portions 55 shown in FIG. 10 are left on the lower surfaces 52 a and 53 a of the movable portion 52 and the fixed portion 53.

  The manufacturing method of the MEMS sensor of this embodiment is applicable to all physical quantity sensors other than the acceleration sensor.

  The internal stress applied to the recess as a closed space formed between the first silicon substrate and the second silicon substrate shown in FIG. 1 was obtained by an ideal gas equation of state (PV = nRT).

  The graph of FIG. 11 shows the relationship between the volume of the recess 11 and the internal stress of the recess 11 at room temperature (at 25 ° C.), and the relationship between the volume of the recess 11 and the internal stress of the recess 11 when heat-treated at 1000 ° C. .

  If the volume V of the recess 11 changes, the amount n of the gaseous substance also changes. If the temperature is constant due to the volume change of the recess 11, the internal stress of the recess does not change.

  Here, when the temperature is raised, the internal stress of the recess as the closed space increases, but as shown in FIG. 11, the internal pressure rises only to about 0.4 MPa at most even when heat treatment at 1000 ° C. is performed. .

  On the other hand, as shown in the next simulation experiment, a strong peeling stress acts locally in a closed space formed by joining the first silicon substrate and the second silicon substrate.

In the experiment, assuming a MEMS sensor having the shape shown in FIG. 12, the Young's modulus of Si is 130 GPa, the Poisson's ratio is 0.28, the Young's modulus of SiO ₂ is 72 GPa, the Poisson's ratio is 0.25, and the initial pressure is 101300 (N / m ² ), the initial temperature was 25 ° C., the gas constant was 8.31 (J / (K · mol)), and the heat treatment temperature was 1000 ° C. The depth of the recess was 250 μm.

  In the experiment, when the R portion shown in FIG. 4 is provided on the side wall of the recess and the radius of curvature of the R portion is 0.00 μm, 0.25 μm, 0.5 μm, 0.75 μm, and 0.9 μm, The distribution of the peeling stress applied near the opening edge was determined. FIG. 13 shows the stress distribution. FIG. 13A shows the stress distribution when the radius of curvature of the R portion is 0.00 μm (that is, the R portion is not formed), and FIG. 13B shows that the radius of curvature of the R portion is 0.50 μm. FIG. 13C shows the stress distribution when the radius of curvature of the R portion is 0.90 μm. As shown in FIG. 13A, in the conventional example in which the R portion is not formed on the side wall of the concave portion, a very strong peeling stress acts near the corner portion of the joint surface side edge portion (opening side edge portion) of the concave portion. I understood it.

  On the other hand, as shown in FIGS. 13B and 13C, when the R portion is formed on the bonding surface side edge (opening side edge) side of the side wall of the recess, the peeling stress is dispersed and the maximum peeling stress is weakened. all right.

  FIG. 14 is a graph showing the relationship between the radius of curvature of the R portion and the maximum peel stress. As shown in FIG. 14, it was found that the maximum peel stress can be reduced by providing the R portion, and the maximum peel stress can be more effectively reduced by increasing the radius of curvature of the R portion.

10, 30, 45 First silicon substrate 11, 40, 46 Recess 11a, 40a, 46a Open side edge (joint surface side edge)
13 Masks 14, 41, 47 Side walls 14 a, 42, 48 Retreat regions 20, 31, 50 Second silicon substrates 21, 32, 49 Oxide insulating layer 25 R parts 33, 34, 53 Fixed parts 35, 52 Movable part 36 Frame Layers 37, 38, 39, 43 Anchor portion 55 Sticking prevention portion

Claims (3)

(A) A bottomed recess is formed on the surface side of the first substrate, and at this time, the recess recedes from the opening side edge toward the bottom surface of the recess in the direction of increasing the width dimension of the recess. Providing a receding region to perform,
(B) forming an oxide insulating layer on at least one of the surface of the first substrate or the surface of the second substrate;
(C) joining the surface of the first substrate and the surface of the second substrate, and performing a heat treatment in a state where the concave portion is a closed space;
A method for manufacturing a MEMS sensor, comprising:   The method of manufacturing a MEMS sensor according to claim 1, wherein in the step (a), the receding region in which the width dimension of the concave portion gradually increases from the opening side edge portion to an intermediate position in the bottom surface direction. Following the step (c),
(D) processing one of the first substrate or the second substrate at the position of the recess formed in the first substrate to form a sensor unit separated into a movable part and a fixed part;
The manufacturing method of the MEMS sensor of Claim 1 or 2 which has these.

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