JP2013052449A - Mems sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an MEMS sensor capable of especially improving bonding strength of a bonding part having Al-Ge eutectic bonding, in comparison with a conventional one.SOLUTION: The MEMS sensor includes: a first base material 21; a second base material 22; and a bonding part 50 positioning between the first base material 21 and the second base material 22 and bonding a first connecting metal layer 54 formed on the first base material 21 side and a second connecting metal layer 55 formed on the second base material 22 side to each other by eutectic bonding. The bonding part 50 includes: a Ta layer 53; the first connecting metal layer 54 formed of Al or an Al alloy; and the second metal connecting layer 55 formed of Ge, in this order from the first base material 21 side to the second base material 22 side. Film thickness t1 of the Ta layer 53 is set within a range at 200-1,500 Å.

Description

  The present invention relates to a MEMS sensor in which a first base material and a second base material are joined via a joint portion.

FIG. 6 is a partial longitudinal sectional view of a conventional MEMS sensor.
In the MEMS sensor 1 shown in FIG. 6, the first base material 2, the second base material 3, and the support base material 4 are laminated in this order, and a sealing joint is formed between the first base material 2 and the second base material 3. 5 is joined. Further, the second base material 3 and the support base material 4 are joined via an insulating layer (silicon oxide layer) 6. Each of the base materials 2 to 4 is made of silicon or the like.

  As shown in FIG. 6, the sealing joint 5 includes an Al layer 8 formed on the first substrate 2 side and a Ge layer 9 formed on the second substrate 3 side at a predetermined heat treatment temperature and temperature. It is formed by eutectic bonding by reduction. As shown in FIG. 6, a Ti layer 7 is formed on the lower surface of the Al layer 8 as a base for improving adhesion to the first base material 2 side. For example, Patent Document 1 below discloses a laminated structure of Ti / Al / Ge.

  However, Ti and Al diffused by heat treatment during eutectic bonding, and TiAl, a brittle material, was formed. For this reason, the bonding strength of the sealing bonded portion 5 deteriorates, and when a stress is applied between the substrates, a peeling problem or the like occurs.

JP-A-9-260385 JP 2004-342287 A WO2006 / 101769 A2 US 7,276,789 B1

  The present invention solves the above-described conventional problems, and in particular, to provide a MEMS sensor capable of improving the bonding strength of a bonded portion having an Al—Ge eutectic bond as compared with the conventional one. Yes.

The MEMS sensor in the present invention is
The 1st base material, the 2nd base material, the 1st connecting metal layer and the 2nd base material which were located between the 1st base material and the 2nd base material, and were formed in the 1st base material side A junction formed by eutectic bonding with the second connection metal layer formed on the side,
The joining portion includes a Ta layer, the first connection metal layer formed of Al or an Al alloy, and the second connection formed of Ge from the first base material side to the second base material side. The connecting metal layers are laminated in this order.

  In the present invention, the bonding portion is laminated in order of the Ta layer, the first connection metal layer made of Al or Al alloy, and the second connection metal layer of Ge from the first base material side to the second base material side. Formed. The Ta layer is a compressive stress as a film stress. For this reason, the adhesiveness with the 1st base material side can be improved. Further, by setting the thickness of the Ta layer to 200 mm to 1500 mm, it is possible to suppress the warping of the base material due to the stress of the Ta layer, and Ta and Al diffuse appropriately, and the Ta layer and the first connection Adhesion between metal layers can be improved. In Patent Documents 1 to 4, in the MEMS sensor as in the present invention, the film is composed of a Ta layer / Al or Al alloy first connection metal layer / Ge second connection metal layer having a thickness of 200 to 1500 mm. The joint is not disclosed.

  As described above, in the present invention, the shear strength between the substrates can be improved as compared with the conventional case. Therefore, the long life and high reliability of the MEMS sensor can be ensured.

  In the present invention, the thickness of the Ta layer is preferably in the range of 600 mm to 1500 mm. As a result, the shear strength can be improved more effectively and stably.

In the present invention, an insulating layer is formed on the surface of the first base material facing the second base material, and a wiring layer is embedded in the insulating layer.
It is possible to effectively apply the bonding portion to the configuration that the bonding portion is formed between the insulating layer and the second base material. In this configuration, it is preferable that the insulating layer made of SiN covering the surface of the wiring layer is formed on the first base material side. Oxygen contained in SiN reacts with Ta, so that the bonding strength between the insulating layer and the Ta layer can be effectively improved. Further, by using SiN, the wiring layer can be appropriately protected without deteriorating the wiring layer.

  Further, in the present invention, Al constituting the first connection metal layer is diffused in the Ta layer, and the Ta concentration in the Ta layer is determined from the interface with the first connection metal layer. It is preferable that it becomes large toward the direction of a 1st base material. Al diffuses largely on the first connecting metal layer side of the Ta layer, and the Al concentration gradually decreases toward the first base material side, while the Ta concentration decreases from the first connecting metal layer side to the first base metal layer side. It gradually increases toward the material side. Thereby, both the adhesiveness with the 1st base material side of Ta layer, and the adhesiveness with a 1st connection metal layer can be improved effectively.

  In the present invention, it is preferable that the Ta concentration is larger than the Al concentration in almost the entire region of the Ta layer in the film thickness direction. By preventing excessive entry of Al into the Ta layer, the shear strength can be effectively improved.

  In the present invention, the Ta concentration is preferably approximately 100% in the vicinity of the interface of the Ta layer with the first base material side. Thus, in the present invention, when the total concentration of Ta and Al is 100%, the Ta concentration in the vicinity of the interface with the first substrate side is almost 100%, that is, a state in which Al is hardly mixed. Thus, the adhesion with the first base material can be effectively improved.

  According to the MEMS sensor of the present invention, the shear strength between the substrates can be improved as compared with the conventional one, and thus the long life and high reliability of the MEMS sensor can be ensured.

FIG. 1A is a schematic diagram (longitudinal sectional view) of the MEMS sensor of the present embodiment, and FIG. 1B is a partially enlarged longitudinal sectional view showing a part of FIG. 1 (c) is a partially enlarged longitudinal sectional view showing the joint shown in FIG. 1 (b) in an enlarged manner. FIG. 2 is a graph showing the film stress of Ta and Ti. FIG. 3 is a graph showing the relationship between the thickness of the Ta layer and the shear strength in the present embodiment. FIG. 4 shows an SEM photograph and an EDS analysis result of the joint in the MEMS sensor of this example. FIG. 5 shows an SEM photograph and an EDS analysis result of the joint in the MEMS sensor of the comparative example. FIG. 6 is a partial longitudinal sectional view of a conventional MEMS sensor.

  FIG. 1A is a schematic diagram (longitudinal sectional view) of the MEMS sensor of the present embodiment, and FIG. 1B is a partially enlarged longitudinal sectional view showing a part of FIG. (C) is the elements on larger scale which expanded and showed the joined part shown in Drawing 1 (b).

  As shown in FIG. 1A, the MEMS sensor 20 includes a first base material 21 and a second base material 22. Both the first base material 21 and the second base material 22 are made of silicon.

As shown in FIG. 1A, the insulating base layer 29 is formed on the entire surface of the surface of the first base material 21 (the surface facing the second base material 22) 21a. As shown in FIG. 1A, the first wiring layer 24 and the second wiring layer 25 are formed on the insulating base layer 29. Further, an insulating layer 23 is formed on the first wiring layer 24 and the second wiring layer 25. As described above, the wiring layers 24 and 25 are embedded in the insulating layer 23. The insulating base layer 29 is formed of a SiO ₂ layer. The insulating layer 23 is made of SiN. The insulating base layer 29 is obtained by thermally oxidizing the surface of the first base material 21 made of silicon. The insulating layer 23 can be formed by an existing method such as a sputtering method. SiN is in a state where the surface is oxidized in the manufacturing stage. The material of each wiring layer 24, 25 is not particularly limited, but is formed of, for example, AlCu.

  In FIG. 1A, a protrusion 23c is formed on the surface 23b of the insulating layer 23 to form a stopper for the movable portion 38 described later, but the shape of the surface 23b of the insulating layer 23 is not particularly limited. The protrusion 23c may be formed integrally with the insulating layer 23 or may be formed separately.

  As shown in FIG. 1A, the second base material 22 is fixedly supported on a support substrate 36 via an oxide insulating layer (ceremonial layer) 35 on the opposite surface side of the first base material 21. An SOI (Silicon on Insulator) substrate can be configured by the second base material 22, the oxide insulating layer 35, and the support substrate 36. The support substrate 36 is made of silicon.

  As shown in FIG. 1A, the second base material 22 includes an anchor portion 37, a movable portion 38, a spring portion 39, and a frame body portion 40. Each part can be configured by etching the second base material 22. The movable part 38 is supported by the anchor part 37 via a spring part 39 so as to be displaceable in the height direction (Z). The movable part 38 and the frame part 40 are separated. The planar shape (the shape of the XY plane) of the frame body portion 40 is formed in a frame shape that surrounds the periphery of the movable portion 38. FIG. 1A shows a cross section of the frame body portion 40 that appears on both sides of the movable portion 38 when the MEMS sensor 20 is cut from the height direction. In addition, the structure and shape of each part of the 2nd base material 22 are not limited to what is shown to Fig.1 (a).

As shown in FIG. 1A, the oxide insulating layer 35 is not formed between the movable portion 38 and the spring portion 39 and the support substrate 36. Therefore, the movable portion 38 can be displaced in the height direction (Z). The oxide insulating layer 35 is preferably formed of SiO ₂ .

  As shown in FIG. 1 (a), a sealing joint 50 formed by laminating a plurality of metal layers is formed between the insulating layer 23 formed on the surface 21 a of the first base 21 and the frame body 40. Is formed. The upper surface of the sealing joint portion 50 is in contact with the frame body portion 40. The lower surface of the sealing joint 50 is in contact with the surface 23b of the insulating layer 23 and is insulated from the wiring layer embedded in the insulating layer 23. In addition, an electrical junction 51 having the same stacked structure as that of the sealing junction 50 is formed between the insulating layer 23 and the anchor portion 37. As shown in FIG. 1A, the upper surface of the electrical joint 51 is in contact with the anchor portion 37 and the lower surface is electrically connected to the second wiring layer 25.

  As shown in FIG. 1A, the first wiring layer 24 crosses the sealing joint 50 from the inner side (inner side surrounded by the frame body part 40) of the sealing joint 50 in a plan view to the outside. Has been pulled out.

  As shown in FIG. 1A, the electrode pad 27 is formed outside the sealing joint 50. A through hole 23a is formed in the insulating layer 23 at the position of the outer end of the first wiring layer 24 for output signals, and the first wiring layer 24 and the electrode pad 27 are electrically connected through the through hole 23a. It is connected.

  As shown in FIG. 1A, the fixed electrode layer 26 is formed on the surface of the insulating layer 23 facing the movable portion 38 in the height direction. The inner end portion of the first wiring layer 24 is electrically connected to the fixed electrode layer 26 through a through hole 23 a formed in the insulating layer 23.

  The material of the fixed electrode layer 26 and the electrode pad 27 shown in FIG. 1A is not particularly limited, but a material excellent in conductivity is preferably applied.

  Further, as shown in FIG. 1A, the anchor portion 37 is electrically connected to the second wiring layer 25 for input signals via the electrical joint portion 51. Although not shown, the second wiring layer 25 is also drawn out of the sealing joint portion 50 and connected to an electrode pad (not shown) similarly to the first wiring layer 24.

  As shown in FIG. 1A, a predetermined gap (gap) is provided in the height direction between the movable portion 38 and the fixed electrode layer 26. In the MEMS sensor 20 shown in FIG. 1A, when the movable portion 38 is displaced in the height direction (Z), the distance to the fixed electrode layer 26 changes, the capacitance changes, and the capacitance changes. Is detected by an electric circuit through the electrode pad 27, for example, a change in acceleration or the magnitude of acceleration can be detected.

  As shown in the enlarged views of FIG. 1B and FIG. 1C, the sealing joint portion 50 extends from the upper surface of the insulating layer 23 to the lower surface of the frame body portion 40, and from the bottom, the Ta layer 53, the first connection. In this structure, the metal layer 54 and the second connection metal layer 55 are stacked in this order. The first connection metal layer 54 is made of Al or an Al alloy, and the second connection metal layer 55 is made of Ge. Examples of the Al alloy include an aluminum copper alloy (AlCu) and an aluminum scandium copper alloy (AlScCu).

  As shown in FIG. 1B, the first connection metal layer 54 and the Ta layer 53 are formed wider in the XY plane than the second connection metal layer 55. Thereby, the 2nd connection metal layer 55 can be joined appropriately within the area of the 1st connection metal layer 54, and stabilization of joining can be aimed at.

  The Ta layer 53 that is the lowermost layer of the sealing joint 50 is formed in contact with and in close contact with the surface 23 b of the insulating layer 23. The second connection metal layer 55 that is the uppermost layer of the sealing joint portion 50 is formed in contact with the lower surface of the frame body portion 40.

  The two layers of the Ta layer 53 and the first connection metal layer 54 are formed on the first base material 21 side by an existing method such as sputtering, and the second connection metal layer 55 includes the second base metal layer 55. It is formed on the material 22 side by an existing method such as sputtering.

  Then, the first connection metal layer 54 and the second connection metal layer 55 are brought into contact with each other and subjected to a predetermined heat treatment while applying a predetermined pressure, so that the first connection metal layer 54 made of Al or an Al alloy and Ge The second connection metal layers 55 are eutectic bonded. Note that a Ge layer is preferably thinly formed on the entire top surface of the first connection metal layer 54. That is, on the first base material 21 side, a Ta layer 53, a first connection metal layer 54, and a thin Ge layer are formed from the bottom, and heat treatment is performed by matching with the second connection metal layer 55 formed of Ge. Apply. Thereby, the 1st connection metal layer 54 and the 2nd connection metal layer 55 can be appropriately eutectic-bonded.

  In the present embodiment, eutectic bonding can be performed by heat treatment at a temperature lower than the melting point of each metal by a combination of materials of the first connection metal layer 54 and the second connection metal layer 55.

  In the present embodiment, the thickness t1 of the Ta layer 53 is in the range of 200 to 1500 mm. The film thickness t2 of the first connection metal layer 54 is about 500 to 1500 mm, and the film thickness of the second connection metal layer 55 is about 300 to 1000 mm.

  Although the sealing joint portion 50 has been described above, the electrical joint portion 51 has the same laminated structure as the sealing joint portion 50.

  FIG. 2 compares the film stresses of Ta and Ti. The film stress data shown in FIG. 2 is when the Ta film thickness is 1000 mm and the Ti film thickness is 1000 mm. FIG. 2 shows the film stress when there is no heat treatment (as-depo) and the film stress when heat treatment is performed at 430 ° C.

  As shown in FIG. 2, Ti turns into tensile stress by heat treatment. On the other hand, Ta is a compressive stress. Conventionally, Ti has been used for the position of the Ta layer 53 of the present embodiment. However, in the case of Ti, a tensile stress is generated by heat treatment, and there is a problem in that separation from the first base material 21 is likely to occur. On the other hand, in the present embodiment, the Ta layer 53 is a compressive stress, and the adhesion between the insulating layer 23 and the sealing joint 50 can be improved.

  In the present embodiment, the thickness of the Ta layer 53 is set in the range of 200 to 1500 mm. By setting the thickness of the Ta layer 53 to 1500 mm or less, it is possible to suppress the warping of the base material due to the stress of the Ta layer 53, and by setting the thickness to 200 mm or more, Ta and Al of the first connection metal layer 54 are moderate. And the bonding strength between the Ta layer 53 and the first connection metal layer 54 is increased, and Al is prevented from reaching the vicinity of the interface between the Ta layer 53 and the insulating layer 23. Deterioration of the bonding strength with the insulating layer 23 is prevented. As a result, the adhesion between the Ta layer 53 and the first connection metal layer 54 can be improved.

  As described above, in this embodiment, the shear strength between the substrates can be improved as compared with the conventional case. As a result, the sealing property can be improved by the sealing bonding part 50, and stable conductivity can be obtained by the electric bonding part 51, and the long life and high reliability of the MEMS sensor 20 can be ensured.

  In the present embodiment, the thickness t1 of the Ta layer 53 is preferably in the range of 600 to 1500 mm. Thereby, the share strength can be improved more stably. Further, the film thickness t1 of the Ta layer 53 is preferably in the range of 600 to 1000 mm. Thereby, it can suppress effectively that the curvature of the base material by the stress of Ta layer 53 arises.

In the present embodiment, the insulating layer 23 made of SiN covering the surfaces of the wiring layers 24 and 25 is formed on the first base material 21 side. A Ta layer 53 is formed on the surface 23 b of the insulating layer 23. The surface of SiN is oxidized at the manufacturing stage, and by superposing SiN and Ta, oxygen contained in SiN reacts with Ta to form oxidized Ta (for example, Ta ₂ O ₅ ), and the insulating layer The bonding strength between the Ta layer 53 and the Ta layer 53 can be effectively improved. Further, by using SiN, the wiring layers 24 and 25 can be appropriately protected without deteriorating the wiring layers 24 and 25. That is, by using SiN, the insulating layer 23 is not formed by applying a high heat treatment temperature or the like, and when the insulating layer 23 is formed, the wiring layers 24 and 25 are not thermally affected. . Further, by using SiN, the difference in thermal expansion coefficient from the base material that is a silicon substrate can be reduced. In addition, it is possible to appropriately form the protrusion 23c on the surface 23b of the insulating layer 23.

  Further, in this embodiment, as described above, Al constituting the first connection metal layer 54 is diffused in the Ta layer 53, and the Ta concentration in the Ta layer 53 is set to the first connection metal layer 54. From the interface 53a to the interface 53b with the insulating layer 23 (see FIG. 1C). Al diffuses much on the first connecting metal layer 54 side of the Ta layer 53, and the Al concentration gradually decreases toward the interface 53b, while the Ta concentration decreases from the first connecting metal layer 54 side to the insulating layer 23. It gradually increases toward the side. Thereby, both the adhesiveness of the Ta layer 53 with the insulating layer 23 and the adhesiveness with the first connection metal layer 54 can be effectively improved.

  Moreover, it is preferable that the Ta concentration is larger than the Al concentration in almost the entire region of the Ta layer 53 in the film thickness direction. By preventing Al from entering excessively into the Ta layer 53, the shear strength can be effectively improved.

  Further, in the vicinity of the interface 53b of the Ta layer 53 with the insulating layer 23, the Ta concentration is preferably approximately 100% when the combined concentration (mass%) of Ta and Al is 100%. As described above, in this embodiment, the Ta concentration near the interface 53b with the insulating layer 23 is almost 100%, that is, Al is hardly mixed, and the adhesion with the insulating layer 23 is effectively improved. Can be improved.

(Experiment of Ta layer thickness t1)
In the experiment, a first connection metal layer and a surface metal layer made of a Ta layer and an AlCu layer were formed on the surface of the first base material 21 made of silicon. The film thickness of the AlCu layer was unified to 8000 mm. The surface metal layer was Ge and the film thickness was unified to 400 mm. On the other hand, a second connection metal layer made of Ge was formed on the surface of the second base material 22. The thickness of the second connecting metal layer was unified to 5000 mm. Then, the first connection metal layer side and the second connection metal layer are overlapped, a load of 7000 N is applied, a heat treatment at 430 ° C. is performed, and the first connection metal layer and the second connection metal layer are combined. Eutectic bonding was performed.

  In the experiment, the thickness of the Ta layer was changed to 0 mm, 200 mm, 400 mm, 500 mm, 600 mm, and 1000 mm, and the shear strength (adhesive strength) necessary for peeling between the substrates was measured. The experimental results are shown in FIG. The shear strength was measured by measuring the force required when the substrates were peeled apart with a shear strength measuring device.

  As shown in FIG. 3, it was found that the shear strength can be improved by increasing the thickness of the Ta layer. However, when the thickness of the Ta layer exceeds about 200 mm, the shear strength is considered to be almost constant. On the contrary, it can be seen that when the thickness of the Ta layer becomes thinner than 200 mm, the shear strength rapidly decreases. When the thickness of the Ta layer exceeds 1500 mm, the stress of the Ta layer becomes too large, and the warpage of the base material becomes large, making it difficult to manufacture the MEMS sensor. Therefore, the thickness of the Ta layer was set to 1500 mm or less. Moreover, as shown in FIG. 3, high shear strength was able to be obtained by using Ta layer 200 or more. Therefore, the thickness of the Ta layer in this example was set in the range of 200 to 1500 mm. Moreover, the preferable range of the film thickness of Ta layer was made into the range of 200 to 1000cm, and the more preferable range of the film thickness of Ta layer was made into the range of 500 to 1000cm. As a result, it was possible to stably obtain a high shear strength.

(EDS experimental results-Examples)
Subsequently, in this example, an EDS analysis of a joint portion in which the Ta layer was 1000 mm and the Al layer was 8000 mm was performed. Moreover, the load at the time of joining was 7000 N, and the heat processing temperature was 430 degreeC.

  The photograph on the right side of FIG. 4 is an SEM photograph at the joint in this example. The left figure of FIG. 4 is an analysis result of EDS (energy dispersive X-ray spectrometer). The vertical line in the SEM photograph of FIG. 4 indicates that EDS analysis was performed at this position. In the EDS analysis result in the left figure, the interface (1) between the Ta layer and the Al layer (first connecting metal layer) and the interface (2) between Ta and the SiN insulating layer on the first substrate surface are dotted lines. It showed in. Ta (1) is the concentration change in the Ta layer, Ta (2) is the concentration change in the Al layer, Al (1) is the concentration change in the Ta layer, and Al (2) is the Al layer. The change in density is shown.

  As shown in the EDS analysis result of FIG. 4, Al (1) is diffused in the Ta layer, but gradually decreases in the downward direction (from the interface (1) with the Al layer toward the first base material). I found it getting smaller. On the other hand, it was found that the Ta (1) concentration in the Ta layer gradually increased in the downward direction (from the interface (1) with the Al layer toward the first base material). It was also found that Ta (2) was diffused in the Al layer. Ta (2) was diffused into the Al layer within a thickness range of about 600 to 700 mm.

  Al (1) diffused over a wide range of the Ta layer, but the Al (1) concentration near the interface (2) was almost 0%. When the total concentration of Ta (1) and Al (1) was 100%, the Ta concentration near the interface (2) was almost 100%. Further, it was found that the Ta (1) concentration was larger than the Al (1) concentration in almost the entire region in the thickness direction of the Ta layer. “Almost” means that the error range is about several percent.

  As shown in FIG. 4, in this embodiment, the Ta (1) concentration in the Ta layer is larger than the Al (1) concentration throughout the region, but the Al (1) concentration in the Ta layer is 1) It is the largest in the vicinity, and it is considered that the bonding strength at the interface (1) is improved. Further, at the interface (2), the Ta (1) concentration is almost 100% and the Al (1) concentration is almost 0%, and the compressive stress of Ta acts appropriately to adhere to the SiN layer (insulating layer). Is considered to have improved.

(EDS experiment result-comparative example)
Subsequently, as a comparative example, a joining portion was formed by laminating Ti layer / Ta layer / AlCu layer / Ge layer in this order from the first base material side to the second base material side (upward in the drawing). The thickness of the Ti layer was 400 mm, the thickness of the Ta layer was 200 mm, the thickness of the AlCu layer was 8000 mm, and the thickness of the Ge layer was 5400 mm. And the load at the time of joining was set to 7000 N, and the heat processing of 430 degreeC was performed.

  The interface (3) of the EDS analysis result in FIG. 5 is the interface between the Ta layer and the AlCu layer, and the interface (4) indicates the interface between the Ti layer and the Ta layer. As shown in FIG. 5, the Al concentration is higher than the Ta concentration between the interface (3) and the interface (4), that is, in the Ta layer, and also below the interface (4), that is, in the Ti layer, It was found that the Al concentration was higher than the concentration. It was also found that Ti was diffused above the interface (3), that is, in the AlCu layer. Thus, in the structure of the comparative example, it turned out that TiAl which is a brittle material is formed in a part of junction part.

  As in the comparative example, by inserting a Ta layer between the Ti layer and the AlCu layer, it is expected that the shear strength can be increased compared to the conventional structure having a Ti / AlCu / Ge laminated structure without inserting Ta. However, in this embodiment, it is possible to further increase the share strength as compared with the configuration of the comparative example.

20 MEMS sensor 21 1st base material 22 2nd base material 23 Insulating layer 24, 25 Wiring layer 26 Fixed electrode layer 27 Electrode pad 36 Support board 37 Anchor part 38 Movable part 40 Frame body part 50 Sealing joint part 51 Electrical junction part 53 Ta layer 54 First connection metal layer 55 Second connection metal layer

Claims (9)

The 1st base material, the 2nd base material, the 1st connecting metal layer and the 2nd base material which were located between the 1st base material and the 2nd base material, and were formed in the 1st base material side A junction formed by eutectic bonding with the second connection metal layer formed on the side,
The joining portion includes a Ta layer, the first connection metal layer formed of Al or an Al alloy, and the second connection formed of Ge from the first base material side to the second base material side. A MEMS sensor, wherein connection metal layers are laminated in this order.   The MEMS sensor according to claim 1, wherein the thickness of the Ta layer is in a range of 200 to 1500 mm.   The MEMS sensor according to claim 1, wherein the thickness of the Ta layer is in a range of 600 to 1500 mm.   2. The MEMS sensor according to claim 1, wherein the thickness of the Ta layer is in a range of 500 to 1000 mm. An insulating layer is formed on the surface of the first base material facing the second base material, and a wiring layer is embedded in the insulating layer;
5. The MEMS sensor according to claim 1, wherein the joint portion is formed between the insulating layer and the second base material.   The MEMS sensor according to claim 5, wherein the insulating layer made of SiN covering the surface of the wiring layer is formed on the first base material side.   Al constituting the first connection metal layer is diffused in the Ta layer, and the Ta concentration in the Ta layer is determined from the interface with the first connection metal layer. The MEMS sensor according to claim 1, wherein the MEMS sensor increases in a direction.   The MEMS sensor according to claim 7, wherein the Ta concentration is larger than the Al concentration in almost the entire region of the Ta layer in the film thickness direction.   9. The MEMS sensor according to claim 7, wherein the Ta concentration is approximately 100% in the vicinity of the interface between the Ta layer and the first base material when the combined concentration of Ta and Al is 100%.

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