JP2018004446A - Semiconductor device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device provided with a sensing unit in a cavity for outputting a sensor signal that corresponds to physical quantity, with which it is possible to suppress an alloy spike under a high-temperature and high-pressure condition, and a method for manufacturing the semiconductor device.SOLUTION: This semiconductor device comprises a support substrate, a cap substrate joined to the support substrate, a support-side pad joined to the support substrate, and a cap-side pad joined to the cap substrate and joined to the opposing support-side pad to form a joined body. An airtight cavity is formed between the support substrate and the cap substrate, with a sensing unit arranged in the cavity. The joined body includes at least two connection areas depending on its formed position, a frame area and a continuity area. The jointed body is joined via a support-side buffer layer with the support substrate therebetween and joined via a cap-side buffer layer with the cap substrate therebetween.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device in which a cavity is formed between a cap substrate and a support substrate, and a sensing unit that outputs a sensor signal corresponding to a physical quantity is provided in the cavity, and a manufacturing method thereof.

  For example, in the physical quantity sensor described in Patent Literature 1, a semiconductor layer serving as a sensing unit is provided in an airtight chamber (cavity) formed by a cap substrate and a support substrate. In the semiconductor layer, a movable portion and a peripheral portion are partitioned by a groove portion. The movable part is movable relative to the cap substrate and the support substrate so that the facing distance between the movable part and the cap substrate changes. Specifically, the movable portion includes a rectangular frame-shaped frame portion in which an opening portion is formed, and a torsion beam provided so as to connect opposite sides of the opening portion. In the movable part, the torsion beam is supported on the support substrate via the anchor part. The movable part is inclined with respect to the cap substrate about the torsion beam as a rotation axis, and as a result, the opposing distance changes.

  A fixed electrode is formed on the cap substrate. As described above, when the facing distance between the semiconductor layer serving as the sensing unit and the cap substrate changes, the capacitance formed by the semiconductor layer and the fixed electrode changes. The physical quantity sensor described in Patent Document 1 converts acceleration applied in the normal direction of the semiconductor layer into rotational movement of the movable portion, and detects acceleration applied to the physical quantity sensor based on a change in capacitance. This is a so-called inertia sensor.

JP 2014-232090 A

  By the way, in the physical quantity sensor described in Patent Document 1, the cap substrate and the support base are joined to ensure airtightness and mechanical strength of the cavity. In this physical quantity sensor, diffusion bonding between the same kinds of metals is used. Another invention uses eutectic bonding between different metals.

  Inertial MEMS sensors that detect changes in capacitance according to the amount of rotation of the moving part as acceleration require higher airtightness and mechanical strength of the cavity than conventional metal bonding, so diffusion bonding In addition, in any joining method of eutectic bonding, a high temperature and high pressure environment is required to realize sufficient diffusion and eutectic of metal atoms. For example, in diffusion bonding between aluminum, it is necessary to perform bonding at a temperature of approximately 400 ° C. and a pressure of 20 MPa to 40 MPa. Since the fluidity of the metal layer pressed under such conditions increases, alloying with the semiconductor material (for example, silicon) constituting the cap substrate or the support substrate, so-called alloy spikes are likely to occur. .

  The alloy spike is generated when silicon is dissolved in the metal and the alloy layer enters the semiconductor substrate. In a normal semiconductor element, this alloy spike reaches the pn junction layer, which causes loss of electrical characteristics such as rectification. On the other hand, in an element that has been mechanically sealed such as inertia MEMS, the mechanism by which alloy spikes affect the function is different. At the locations where alloy spikes are generated, the metal layer concentration becomes uneven or segregation occurs. Since the hardness and strength are different from the original metal material at the location where such non-uniform concentration and segregation occur, it causes a decrease in mechanical strength and loss of airtightness.

  The present invention has been made in view of the above problems, and in a semiconductor device provided with a sensing unit that outputs a sensor signal corresponding to a physical quantity in a cavity, a semiconductor device capable of suppressing alloy spikes even under high temperature and high pressure. And it aims at providing the manufacturing method.

  The invention disclosed herein employs the following technical means to achieve the above object. Note that the reference numerals in parentheses described in the claims and in this section indicate a corresponding relationship with specific means described in the embodiments described later as one aspect, and limit the technical scope of the invention. Not what you want.

To achieve the above object, the present invention includes a support substrate (10) having a first surface (10a) including a layer containing a semiconductor as a main component, and a second surface including a layer having a semiconductor as a main component. (40a), a cap substrate (40) bonded to the support substrate in a state where the second surface faces the first surface, and a support side pad (made of metal and bonded to the first surface of the support substrate) 31a to 36a) and cap side pads (31b to 36b) made of metal, joined to the second surface of the cap substrate, and joined to the opposing support side pads to form the joined bodies (31 to 36). A semiconductor device in which an airtight cavity (80) is formed between a support substrate and a cap substrate, and a sensing unit that outputs a sensor signal corresponding to a physical quantity is disposed in the cavity,
The joined body includes a frame region (A) responsible for the mechanical strength of joining the support substrate and the cap substrate and a conduction region (B, C, D) responsible for electrical connection between the layers depending on the formation position. The joined body includes at least two connection regions, and the bonded body includes a support side buffer layer (92, 92i, 93i, 96i), a barrier metal film (92b, 93b, 96b) or both between the support substrate and the support substrate. 93, 96) and a cap-side buffer layer including an insulating film (42) and / or a barrier metal film (42b) between the cap substrate and the cap substrate.

  According to this, in the frame region and the conduction region, the support side buffer layer is provided between the joined body and the support substrate, and the cap side buffer layer is provided between the joined body and the cap substrate. Therefore, the bonded body, the support substrate, and the cap substrate are not in direct contact. For this reason, the alloy spike accompanying the alloying of the semiconductor and the metal can be suppressed even under high temperature and high pressure when the support side pad and the cap side pad are subjected to diffusion bonding or thermocompression bonding. As a result, the airtight reliability in the cavity can be improved together with the mechanical reliability of the semiconductor device.

It is a figure which shows the structure of the inertial sensor concerning 1st Embodiment, and is sectional drawing which follows the II line | wire shown in FIG. It is a top view which shows the structure of the inertial sensor concerning 1st Embodiment. It is sectional drawing which shows the detailed structure of the conjugate | zygote and support side buffer layer in a flame | frame area | region. It is sectional drawing which shows the detailed structure of the conjugate | zygote and support side buffer layer in a flame | frame area | region. It is sectional drawing which shows the detailed structure of the conjugate | zygote in a conduction | electrical_connection area | region, and a support side buffer layer. It is sectional drawing which shows the detailed structure of the conjugate | zygote in a conduction | electrical_connection area | region, and a support side buffer layer. It is sectional drawing which shows the detailed structure of the conjugate | zygote in a conduction | electrical_connection area | region, and a support side buffer layer. It is sectional drawing which shows the detailed structure of the conjugate | zygote and support side buffer layer in an electrode area | region. It is sectional drawing which shows the detailed structure of the conjugate | zygote and support side buffer layer in an electrode area | region. It is sectional drawing which shows the process of preparing a support substrate. It is sectional drawing which shows the process of forming an insulating film in a support substrate. It is sectional drawing which shows the process of patterning an insulating film. It is sectional drawing which shows the process of forming a barrier metal film. It is sectional drawing which shows the process of patterning a barrier metal film. It is sectional drawing which shows the process of forming the metal film used as a support side pad. It is sectional drawing which shows the process of patterning a support side pad. It is sectional drawing which shows the process of preparing a cap board | substrate. It is sectional drawing which shows the process of patterning a cap side pad. It is sectional drawing which shows the process of joining a support substrate and a cap board | substrate. It is sectional drawing which shows the process of thinning a cap board | substrate. It is sectional drawing which shows the process of forming a through-hole in a cap board | substrate. It is sectional drawing which shows the process of forming a penetration electrode. It is a top view which shows the structure of the inertial sensor concerning 2nd Embodiment. It is sectional drawing which shows the detailed structure of the conjugate | zygote in a interlayer connection area | region, a support side buffer layer, and a cap side buffer layer. It is sectional drawing which shows the detailed structure of the conjugate | zygote in a interlayer connection area | region, a support side buffer layer, and a cap side buffer layer. It is sectional drawing which shows the detailed structure of the conjugate | zygote in a interlayer connection area | region, a support side buffer layer, and a cap side buffer layer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same reference numerals are given to the same or equivalent parts.

(First embodiment)
First, a schematic configuration of the semiconductor device according to the present embodiment will be described with reference to FIGS.

  The semiconductor device in this embodiment is an inertial sensor that detects acceleration, for example. As shown in FIG. 1, the inertial sensor 100 as a semiconductor device is configured by stacking a support substrate 10 and a cap substrate 40. 1 is a cross-sectional view taken along the line II shown in FIG. FIG. 2 is a top view of the second substrate 13 of the support substrate 10.

  The support substrate 10 is an SOI (Silicon on Insulator) substrate in which a second substrate 13 is disposed on the first substrate 11 via an insulating film 12, and the first surface 10 a is an insulating film of the second substrate 13. It is composed of a surface on the side opposite to the 12 side. The first substrate 11 is made of a semiconductor such as silicon, the insulating film 12 is made of an oxide film or a nitride film, and the second substrate 13 is made of single crystal silicon or the like.

  As shown in FIGS. 1 and 2, the second substrate 13 is subjected to micromachining to form a groove portion 14, and the movable portion 20 and the peripheral portion 30 are partitioned by the groove portion 14.

  Further, in the support substrate 10, the first substrate 11 has a portion facing the movable portion 20 in order to prevent the movable portion 20 and the frame portion 22 described later from coming into contact with the first substrate 11 and the insulating film 12. A recess 15 is formed. The recess 15 is formed by a method such as etching, and the insulating film 12 is formed over the surface of the recess 15.

  The movable portion 20 includes a rectangular frame-shaped frame portion 22 in which a planar rectangular opening portion 21 is formed, and a torsion beam 23 formed so as to connect opposite sides of the opening portion 21. The movable portion 20 is supported by the first substrate 11 by connecting the torsion beam 23 to the anchor portion 24 supported by the insulating film 12.

  Here, the definition of the direction in this embodiment is demonstrated. As shown in FIGS. 1 and 2, the extending direction of the torsion beam 23 is defined as the x-axis direction, and the direction orthogonal to the x-axis is defined as the y-axis direction. A direction orthogonal to the xy plane is taken as a z-axis direction. That is, the z-axis direction is a normal direction of the first surface 10 a of the support substrate 10. In other words, the z-axis direction is the thickness direction of the support substrate 10 and the cap substrate 40.

  The torsion beam 23 is a member that becomes the rotation center of the movable portion 20 when acceleration in the z-axis direction is applied. That is, the torsion beam 23 rotates with the extending direction as a rotation axis. The torsion beam 23 in the present embodiment is formed so as to divide the opening 21 into two.

  The frame portion 22 has an asymmetric shape with respect to the torsion beam 23 so that it can rotate around the torsion beam 23 when an acceleration in the z-axis direction is applied. The frame portion 22 in this embodiment is divided into a first portion 22a and a second portion 22b with the torsion beam 23 as a reference. The frame 22 has a length in the y-axis direction from the torsion beam 23 in the first part 22a to the end of the part farthest from the torsion beam 23 to the end of the part farthest from the torsion beam 23 in the second part 22b. Is shorter than the length in the y-axis direction. In other words, the frame portion 22 is configured such that the mass of the first portion 22a is smaller than the mass of the second portion 22b.

  Further, on the first surface 10 a of the support substrate 10, that is, on the surface of the second substrate 13, the first bonded body 31, the second bonded body 32, the third bonded body 33, the fourth bonded body 34, and the fifth bonded body 35. And a sixth joined body 36 that functions as an airtight frame is formed. In the present embodiment, the bonded bodies 31 to 36 are made of aluminum, for example, and are formed between the support substrate 10 and the cap substrate 40. In FIG. 2, the formation positions of these elements are indicated by broken lines.

  Specifically, the first joined body 31 is formed in the peripheral portion 30 and connected to a first through electrode 71 described later on the second surface 40a. The second joined body 32 is formed on the anchor portion 24 and is electrically connected to the movable portion 20. The third bonded body 33 is formed in the peripheral portion 30 and connected to a second through electrode 72 described later on the second surface 40a. The fourth joined body 34 is formed in the peripheral portion 30 and connected to a third through electrode (not shown) on the second surface 40a. The fifth joined body 35 is formed in the peripheral portion 30 and connected to a fourth through electrode (not shown) on the second surface 40a. The third through electrode and the fourth through electrode have the same configuration as the first through electrode 71 and are formed side by side along the y-axis direction. That is, the potentials of the first joined body 31, the third joined body 33, the fourth joined body 34, and the fifth joined body 35 are the first through electrode 71, the second through electrode 72, the third through electrode, and the fourth, respectively. It has the same potential as the through electrode, and can be output to the outside through these electrodes. Conversely, when a voltage is applied to these electrodes, the corresponding bonded body can be brought to a desired potential.

  Furthermore, the first joined body 31 and the second joined body 32 are connected and electrically connected to each other by a relay wiring 63 described later. That is, the potential of the movable portion 20 can be taken out from the first through electrode 71.

  The sixth joined body 36 functioning as an airtight frame is formed in a frame shape so as to surround the movable portion 20 (groove portion 14). Since the sixth joined body 36 is formed between the support substrate 10 and the cap substrate 40, the region surrounded by the sixth joined body 36, the support substrate 10 and the cap substrate 40 is isolated from the outside. It is an airtight space. The cavity described in the claims corresponds to the isolation space. Hereinafter, this isolation space is referred to as a cavity 80. A detailed structure of each of the joined bodies 31 to 36 will be described later.

  As shown in FIGS. 1 and 2, the second substrate 13 in the support substrate 10 has a plurality of slits 50 in the outer peripheral portion 30. The second substrate 13 in this embodiment has a first type slit 51 and a second type slit 52. Hereinafter, the first type slit 51 and the second type slit 52 may be collectively referred to as a slit 50.

  The first type slit 51 is formed in a substantially annular shape so as to surround a contact portion of the second substrate 13 with the first bonded body 31, the third bonded body 33, the fourth bonded body 34, and the fifth bonded body 35. ing. As shown in FIG. 2, the first type slit 51 that surrounds the contact portion with the first pad portion 31 is annular, and the region surrounded by the slit is hereinafter referred to as an island portion 30 a. That is, the peripheral portion 30 is partitioned by the first type slit 51 into an island portion 30a and a base body portion 30b excluding the island portion 30a. In the present embodiment, as shown in FIG. 1, the first type slit 51 does not reach the first substrate 11 or the insulating film 12, but the present invention is not limited to this. The island part 30 a and the base part 30 b are concepts including the first substrate 11 and the insulating film 12.

  Similar to the first bonded body 31, the first type slit 51 is formed so as to surround the contact portion of the second substrate 13 with the third bonded body 33. The first type slit 51 corresponding to the third joined body 33 does not form a complete ring, but forms a C shape with a part missing. Similarly, the first type slit 51 is formed so as to surround the contact portion with the fourth bonded body 34 in the second substrate 13, and the first type slit 51 is set so as to surround the contact portion with the fifth bonded body 35. Is formed. The first type slit 51 corresponding to the fourth joined body 34 and the fifth joined body 35 has an annular shape, and divides the island portion 30a and the base portion 30b.

  As shown in FIG. 2, the second type slit 52 is formed in a frame shape so as to include the movable portion 20 and the contact portions of the peripheral portion 30 with the joined bodies 31 and 33 to 35 inside. Yes. The second type slit 52 in the present embodiment is formed in a rectangular shape along the sixth joined body 36 in the frame in which the sixth joined body 36 is formed. The second type slit 52 partitions the second substrate 13 into an outer peripheral part 30c that is outside the frame of the second type slit 52 and an inner peripheral part 30d that is inside the frame. When viewed from the front in the z-axis direction, the outer peripheral portion 30c is a region of the support substrate 10 to which the sixth joined body 36 is joined. On the other hand, the inner peripheral part 30d is an area including the movable part 20 and the above-described island part 30a.

  As shown in FIG. 1, the cap substrate 40 includes a bonded substrate 41, an insulating film 42 formed on one surface of the bonded substrate 41 facing the support substrate 10, and the bonded substrate 41 on the support substrate 10 side. And an insulating film 43 formed on the opposite surface. A second surface 40 a of the cap substrate 40 is formed on the surface of the insulating film 42 facing the support substrate 10. The bonded substrate 41 is made of silicon, the insulating film 42 is made of an oxide film or a nitride film, and the insulating film 43 is made of TEOS or the like.

  As shown in FIG. 2, the first fixed electrode 61 and the second fixed electrode 62 are formed on the second surface 40 a of the cap substrate 40. Hereinafter, the first fixed electrode 61 and the second fixed electrode 62 may be collectively referred to as a fixed electrode 60. The fixed electrode 60 is disposed so as to face the support substrate 10 and is formed so as not to contact the first surface 10a.

  As shown in FIG. 2, the first fixed electrode 61 is formed so as to overlap the first portion 22 a in the frame portion 22 when viewed from the z-axis direction. In other words, the first fixed electrode 61 faces the first portion 22a. The first fixed electrode 61 and the first portion 22a constitute an electrostatic capacity, and the electrostatic capacity changes as the movable part 20 is displaced with the torsion beam 23 as a rotation axis. The first fixed electrode 61 is electrically connected to the fifth pad portion 35 via the first wiring 61a. That is, the potential of the first fixed electrode 61 can be detected through the fourth through electrode.

  As shown in FIG. 2, the second fixed electrode 62 is formed so as to overlap the second portion 22 b in the frame portion 22 when viewed from the front in the z-axis direction. In other words, the second fixed electrode 62 faces the second portion 22b. The second fixed electrode 62 and the second portion 22b constitute an electrostatic capacity, and the electrostatic capacity changes as the movable part 20 is displaced with the torsion beam 23 as a rotation axis. The second fixed electrode 62 is electrically connected to the fourth pad portion 34 via the second wiring 62a. That is, the potential of the second fixed electrode 62 can be detected via the third through electrode.

  Note that the fixed electrode 60, the first wiring 61a, and the second wiring 62a are conductive materials, and are made of, for example, aluminum. Further, the first fixed electrode 61 and the second fixed electrode 62 have the same planar shape, and form the same capacitance between the first and second portions 22a and 22b when no acceleration is applied. doing.

  Further, the relay wiring 63 is formed on the second surface 40a of the cap substrate 40 along the second surface 40a. The relay wiring 63 is made of, for example, aluminum, and electrically connects the first joined body 31 and the second joined body 32. The relay wiring 63 allows the second joined body 32 and the first joined body 31 and thus the first through electrode 71 to be at the same potential. Note that the relay wiring 63 in the present embodiment extends in the x-axis direction so as to face the torsion beam 23. Here, the first wiring 61a, the second wiring 62a, and the relay wiring 63 described above are wirings formed in the cavity 80, and are so-called inner layer wirings. These inner layer wirings 61a, 62a, and 63 are formed on the insulating film 42 in the cap substrate 40, and have a structure that does not directly contact the bonded substrate 41 mainly composed of silicon.

  Thus, a sensing part is comprised by the movable part 20 and the fixed electrode 60, and the sensor signal according to acceleration can be output now by the 1st penetration electrode 71, the 3rd penetration electrode, and the 4th penetration electrode. ing.

  Further, the through electrode 70 penetrating in the thickness direction (z-axis direction) is formed in the cap substrate 40. The through electrode 70 in the present embodiment includes the first through electrode 71 and the second through electrode 72 shown in FIG. 1, and the four through electrodes, a third through electrode and a fourth through electrode (not shown). These four through electrodes may be collectively referred to as a through electrode 70.

  The four through electrodes 70 are equivalent to each other, and are formed in a through hole 41a penetrating the bonded substrate 41 and the insulating film 42 via an insulating film 41b. The insulating film 41b is an integral insulating film connecting the insulating film 42 and the insulating film 43 on the inner wall surface of the through hole 41a. The through electrode 70 is formed along the inner wall surface of the through hole 41 a, and the land portion 70 a is formed on the insulating film 43.

  As shown in FIG. 1, the first through electrode 71 passes through the insulating film 42 and reaches the first bonded body 31. That is, the first through electrode 71 is electrically connected to the movable portion 20 via the first joined body 31, the relay wiring 63, and the second joined body 32. The second through electrode 72 passes through the insulating film 42 and reaches the third bonded body 33. The second through electrode 72 is also in electrical contact with the bonded substrate 41. Since the bonded body 33 is in electrical contact with the peripheral portion 30 of the second substrate 13, the bonded substrate 41 and the peripheral portion 30 are at the same potential. For example, if the second through electrode 72 is set to the ground potential in the inertial sensor 100, the bonded substrate 41 and the peripheral portion 30 can be set to the ground potential. A third through electrode and a fourth through electrode (not shown) penetrate the insulating film 42 and reach the fourth joined body 34 and the fifth joined body 35, respectively. That is, the third through electrode and the fourth through electrode are electrically connected to the second fixed electrode 62 and the first fixed electrode 61, respectively.

  The above is the schematic structure of the inertial sensor 100 in the present embodiment. In such an inertial sensor 100, when an acceleration in the z-axis direction is applied, the frame portion 22 rotates according to the acceleration with the torsion beam 23 as a rotation axis. And since the electrostatic capacitance between the 1st site | part 22a and the 1st fixed electrode 61 and the electrostatic capacitance between the 2nd site | part 22b and the 2nd fixed electrode 62 change according to an acceleration, this capacity | capacitance. The acceleration is detected based on the change. That is, the inertial sensor 100 is a Z-axis inertial sensor.

  Next, with reference to FIG. 3 to FIG. 9, the detailed structure of the joined bodies 31 to 36 and the vicinity thereof will be described.

  The bonded bodies 31 to 36 are formed by bonding a support side pad formed on the support substrate 10 and a cap side pad formed on the cap substrate 40, respectively. Specifically, the first bonded body 31 is formed by bonding a first support side pad 31a and a first cap side pad 31b. The second bonded body 32 is formed by bonding the second support side pad 32a and the second cap side pad 32b. The third bonded body 33 is formed by bonding the third support side pad 33a and the third cap side pad 33b. The fourth bonded body 34 is formed by bonding the fourth support side pad 34a and the fourth cap side pad 34b. The fifth bonded body 35 is formed by bonding a fifth support side pad 35a and a fifth cap side pad 35b. The sixth joined body 36 is formed by joining the sixth support side pad 36a and the sixth cap side pad 36b.

  Note that, among the joined bodies 31 to 36, the support side pads 31a to 36a, and the cap side pads 31b to 36b, those not shown in the drawings are also given reference numerals for convenience of explanation.

  The joined bodies 31 to 36 in the present embodiment are classified into three types of regions depending on their formation positions and functions. That is, as shown in FIG. 1, the three types of regions are a frame region A for securing airtightness and mechanical strength, a conduction region B for securing conduction between different substrates or layers, and a through electrode. This is an electrode region C for ensuring electrical continuity between 70 and the second substrate 13. Each region will be specifically described below.

<Frame area>
The sixth joined body 36 belongs to the frame region A. In the sixth joined body 36, two opposing pads are joined together to be integrated. Specifically, as shown in FIG. 3, the sixth joined body 36 includes a sixth support-side pad 36a formed on the support substrate 10 side, and a sixth cap-side pad 36b formed on the cap substrate 40 side. Are integrally joined to each other by diffusion bonding or thermocompression bonding using the opposing surfaces as bonding surfaces. The sixth support side pad 36a is bonded to the second substrate 13 in the support substrate 10 via the insulating film 96i. The main component of the sixth support side pad 36a is aluminum, and the main component of the second substrate 13 is silicon, but these are not in direct contact with each other, and the insulating film 96i made of a silicon oxide film or nitride film is formed. It is in the state joined mutually. On the other hand, the sixth cap-side pad 36b is bonded to the cap substrate 40 via an insulating film 42 formed on the second surface 40a side of the cap substrate 40. The main component of the sixth cap side pad 36b is aluminum, and the main component of the bonded substrate 41 is silicon. However, these are not in direct contact with each other, and the insulating film 42 made of a silicon oxide film or nitride film is provided. It is in the state joined mutually. As described above, the sixth joined body 36 formed by integrally joining the sixth support side pad 36a and the sixth cap side pad 36b exists independently without contacting a site mainly composed of silicon. ing.

  In the frame region A, the insulating film 96i formed between the sixth support side pad 36a and the support substrate 10 may be replaced with a barrier metal film 96b as shown in FIG. When the barrier metal film 96i is mainly composed of at least one of titanium (Ti), titanium nitride (TiN), tantalum (Ta), and tantalum nitride (TaN), aluminum constituting the sixth bonded body 36 is formed. It is preferable that an alloy is not easily formed between the two. In addition, the film that mediates between the sixth bonded body 36 and the support substrate 10 is not limited to the form in which the insulating film 96i or the barrier metal film 96b is configured alone. For example, the insulating film 96i may be formed on the support substrate 10, the barrier metal film 96b may be formed on the insulating film 96i, and the barrier metal film 96b and the sixth bonded body 36 may be bonded.

  The support-side buffer layer described in the claims is a concept that collectively refers to layers that mediate between each of the joined bodies 31 to 36 and the support substrate 10, and in the frame region A in the present embodiment, The configuration including only the insulating film 96i, the configuration including only the barrier metal film 96b, and the configuration including both are referred to as a sixth support-side buffer layer 96 as a concept including all of them.

  Similar to the support-side buffer layer, the cap-side buffer layer described in the claims is a concept that collectively refers to a layer that mediates between each of the joined bodies 31 to 36 and the cap substrate 40. In the frame region A, the insulating film 42 corresponds to a cap side buffer layer.

<Conduction area>
The second joined body 32 belongs to the conduction region B. In the second bonded body 32, two opposing pads are bonded to each other and integrated. Specifically, as shown in FIG. 5, the second bonded body 32 includes a second support side pad 32a formed on the support substrate 10 side, and a second cap side pad 32b formed on the cap substrate 40 side. Are integrally joined to each other by diffusion bonding or thermocompression bonding using the opposing surfaces as bonding surfaces.

  The second support side pad 32a is joined to the second substrate 13 in the support substrate 10 and eventually to the movable portion 20 via the insulating film 92i. The insulating film 92i has a contact hole 92h penetrating in a cylindrical shape. A contact portion 32c made of the same material as that of the second support side pad 32a is formed in the contact hole 92h so as to fill the contact hole 92h. The contact portion 32c is integrally formed with the second support side pad 32a on one side of the opening of the contact hole 92h, and is in contact with the second substrate 13 on the other side of the opening. That is, the second support side pad 32a is electrically connected to the second substrate 13 through the contact portion 32c.

  On the other hand, the second cap side pad 32 b is bonded to the cap substrate 40 via an insulating film 42 formed on the second surface 40 a side of the cap substrate 40. The main component of the second cap-side pad 32b is the same aluminum as the second support-side pad 32a, and the main component of the bonded substrate 41 is silicon, but these are not in direct contact with each other, and the silicon oxide film Further, they are joined to each other via an insulating film 42 made of a nitride film. The relay wiring 63 responsible for the electrical connection between the first joined body 31 and the second joined body 32 is connected to the second cap side pad 32b, and is connected to the first joined body 31 along the insulating film 42. It is extended toward.

  As in the case of the frame region A, in the conductive region B, the insulating film 92i corresponds to the support-side buffer layer described in the claims, and an aspect including a barrier metal layer 92b as will be described later. Can be adopted. The insulating film 42 corresponds to a cap-side buffer layer described in the claims. The form composed only of the insulating film 92i, the form composed only of the barrier metal film 92b, and the form including both are referred to as the second support side buffer layer 92 as a concept including all.

  When viewed in front from the z-axis direction, the second joined body 32 has a circular shape. The second support side buffer layer 92 also has an annular shape in which the contact hole 92h is hollowed out. The second joined body 32 overlaps the insulating film 42 as the second support side buffer layer 92 and the cap side buffer layer, except for a portion where the contact portion 32c overlaps. In the overlapped portion, the second bonded body 32 is bonded to the cap substrate 40 and the support substrate 10 via the insulating films 42 and 92i, respectively, so that the mechanical strength is ensured. On the other hand, the contact part 32 c has a structure that secures a conduction path between the second substrate 13 having the movable part 20 and the relay wiring 63.

  Although not shown, a structure in which a barrier metal film 92b is interposed between the second support side pad 32a and the support substrate 10 may be employed as the second support side buffer layer 92, as in the frame region A. In this case, it is not necessary to provide the contact hole 92h, and the barrier metal film 92b electrically connects the support substrate 10 and the second support side pad 32a. Further, as shown in FIG. 6, an insulating film 92i having a contact hole 92h is formed on the support substrate 10, and the second wall exposed by forming the inner wall of the contact hole 92h and the contact hole 92h on the insulating film 92i. The barrier metal film 92b may be formed on the substrate 13, and the barrier metal film 92b and the second bonded body 32 may be bonded. In this case, when viewed from the front in the z-axis direction, the second bonded body 32 is preferably present on the inner side of the outermost contour line of the barrier metal film 92b. In the configuration in which the barrier metal film 92b described with reference to FIG. 5 does not exist, the contact portion 32c and the second substrate 13 are in direct contact and are electrically connected to each other. On the other hand, in the configuration shown in FIG. 6, the barrier metal film 92b is inserted between the contact portion 32c and the second substrate 13 in the contact hole 92h. As described above, the second joined body 32 formed by integrally joining the second support-side pad 32a and the second cap-side pad 32b shown in FIG. Exist.

  Further, the second cap side pad 32b may be formed in an annular shape. As shown in FIG. 7, when viewed from the front in the z-axis direction, the hollow portion in the ring overlaps with the formation position of the contact hole 92h. In other words, when viewed from the front in the z-axis direction, the entire second cap side pad 32b overlaps the insulating film 42 as the second cap side buffer layer. When such a form is adopted, the relay wiring 63 and the second substrate 13 can be electrically connected without causing the contact portion 32c, which may be alloyed over time, to have mechanical strength.

<Electrode region>
The first joined body 31, the third joined body 33, the fourth joined body 34, and the fifth joined body 35 belong to the electrode region C. Since the four joined bodies 31, 33 to 35 and their peripheral structures are substantially equivalent to each other, the third joined body 33 and the second through electrode 72 electrically connected to the third joined body 33 are here. Only explained.

  In the third joined body 33, two opposing pads are joined together. Specifically, as shown in FIG. 8, the third joined body 33 includes a third support side pad 33a formed on the support substrate 10 side, and a third cap side pad 33b formed on the cap substrate 40 side. Are integrally joined to each other by diffusion bonding or thermocompression bonding using the opposing surfaces as bonding surfaces.

  The third support side pad 33a is bonded to the second substrate 13 in the support substrate 10 via the insulating film 93i. The insulating film 93i has a contact hole 93h penetrating in a cylindrical shape. A contact portion 33c made of the same material as the third support side pad 33a is formed in the contact hole 93h so as to fill the contact hole 93h. The contact portion 33c is formed integrally with the third support side pad 33a on one side of the opening of the contact hole 93h, and is in contact with the second substrate 13 on the other side of the opening. That is, the third support side pad 33a is electrically connected to the second substrate 13 via the contact portion 33c.

  On the other hand, the third cap-side pad 33b is bonded to the cap substrate 40 via the insulating film 42 formed on the second surface 40a side of the cap substrate 40, and the second through electrode 72 penetrating the cap substrate 40 and They are in electrical contact. The main component of the third cap side pad 33b is the same aluminum as the second support side pad 32a, and the main component of the bonded substrate board 41 is silicon, but these are not in direct contact with each other, and the silicon oxide film Further, they are joined to each other via an insulating film 42 made of a nitride film.

  In the electrode region C, the insulating film 93i corresponds to the support side buffer layer described in the claims, and an embodiment including a barrier metal layer 93b can be adopted as will be described later. The insulating film 42 corresponds to a cap-side buffer layer described in the claims. The form constituted only by the insulating film 93i, the form constituted only by the barrier metal film 93b, and the form including both are referred to as a third support side buffer layer 93 as a concept including all of them.

  When viewed from the front in the z-axis direction, the third joined body 33 has a circular shape. The third support-side buffer layer 93 also has an annular shape with the contact hole 93h portion cut out. The third bonded body 33 overlaps the third support side buffer layer 93 and the insulating film 42 as the cap side buffer layer, except for a portion where the contact portion 33c overlaps. In the overlapped portion, the third bonded body 33 is bonded to the cap substrate 40 and the support substrate 10 via the insulating films 42 and 93i, respectively, so that the mechanical strength is ensured. On the other hand, the contact portion 33 c has a structure that secures a conduction path between the second substrate 13 having the movable portion 20 and the second through electrode 72.

  Although not shown, a structure in which a barrier metal film 93 b is interposed between the third support side pad 33 a and the support substrate 10 may be employed as the third support side buffer layer 93 as in the frame region A. In this case, it is not necessary to provide the contact hole 93h, and the barrier metal film 93b electrically connects the support substrate 10 and the third support side pad 33a. Further, as shown in FIG. 9, an insulating film 93i having a contact hole 93h is formed on the support substrate 10, and the second wall exposed by the formation of the contact hole 93h and the inner wall of the contact hole 93h on the insulating film 93i. The barrier metal film 93b may be formed on the substrate 13, and the barrier metal film 93b and the third bonded body 33 may be bonded. In this case, it is preferable that the third joined body 33 exists inside the outermost contour line of the barrier metal film 93b when viewed from the z-axis direction. In the configuration in which the barrier metal film 93b described with reference to FIG. 8 does not exist, the contact portion 33c and the second substrate 13 are in direct contact and are electrically connected to each other. On the other hand, in the configuration shown in FIG. 9, the barrier metal film 93b is inserted between the contact portion 33c and the second substrate 13 in the contact hole 93h. As described above, the third joined body 33 formed by integrally joining the third support side pad 33a and the third cap side pad 33b shown in FIG. 9 is independent without contacting a site mainly composed of silicon. Exist.

  Further, the third cap side pad 33b may be formed in an annular shape. When viewed from the front in the z-axis direction, the hollow portion of the annular ring overlaps with the formation position of the contact hole 93h. In other words, when viewed from the front in the z-axis direction, the entire third cap side pad 33b overlaps the insulating film 42 as the third cap side buffer layer. By adopting such a configuration, the second through electrode 72 and the second substrate 13 can be electrically connected without causing the contact portion 33c, which may be alloyed over time, to have mechanical strength. .

  The structure of the first joined body 31 and the first through electrode 71, the structure of the fourth joined body 34 and the third through electrode, and the structure of the fifth joined body 35 and the fourth through electrode are respectively the joined body and the through electrode. Therefore, a structure similar to the electrode region C can be adopted. However, the first joined body 31, the fourth joined body 34, and the fifth joined body 35 do not necessarily need to ensure electrical continuity with the second substrate 13, so the joined bodies 31, 34, 35 and the second substrate 13 An insulating film having no contact hole may be employed as the support side buffer layer inserted therebetween. According to this, the 1st joined body 31, the 4th joined body 34, and the 5th joined body 35 exist independently, without contacting the site | part which has silicon as a main component.

  In the present embodiment, the conductive region B and the electrode region C are described separately. However, the joined body in the conductive region B and the electrode region C is interposed between different conductive layers and contributes to electrical conduction between layers. Therefore, both are concepts included in the conduction region described in the claims.

  Next, a manufacturing method of the inertial sensor 100 will be described with reference to FIGS.

  First, as shown in FIG. 10, a support substrate 10 is prepared. For manufacturing the support substrate 10, first, a first substrate 11 made of, for example, silicon is prepared, a mask resist (not shown) is formed on the first substrate 11, etching is performed, and the depression 15 is formed on the first substrate 11. Form. Thereafter, the insulating film 12 is formed on the first substrate 11 by a generally known method such as CVD or thermal oxidation. Next, the support substrate 10 is formed by bonding the insulating film 12 and the second substrate 13. The bonding of the insulating film 12 and the second substrate 13 is not particularly limited, but can be performed as follows, for example.

  First, the bonding surface of the insulating film 12 and the bonding surface of the second substrate 13 are irradiated with N 2 plasma, O 2 plasma, or Ar ion beam to activate the bonding surfaces of the insulating film 12 and the second substrate 13. Then, alignment by an infrared microscope or the like is performed using an appropriately formed alignment mark, and the insulating film 12 and the second substrate 13 are bonded by so-called direct bonding at room temperature to 550 ° C. Although the direct bonding is described as an example here, the insulating film 12 and the second substrate 13 may be bonded by a bonding technique such as anodic bonding, intermediate layer bonding, or fusion bonding. Further, after the joining, a treatment for improving the joining quality such as high temperature annealing may be performed. Further, after bonding, the second substrate 13 may be processed to a desired thickness by grinding and polishing.

  Next, as shown in FIG. 11, an insulating film i constituting the support side buffer layer is formed on the second substrate 13 by a generally known method such as CVD.

  Next, as shown in FIG. 12, a mask resist (not shown) is formed on the insulating film i, and etching is performed to pattern the insulating film i. By this step, the insulating film 96 i constituting the sixth support side buffer layer 96 is formed in the frame region A. The insulating film 96 i is formed in a frame shape along the shape of the sixth joined body 36. In addition, an insulating film 92 i constituting the second support side buffer layer 92 is formed in the conduction region B. In addition, an insulating film 93i that constitutes the third support-side buffer layer 93 is formed in the electrode region C, and at the same time, supports corresponding to the first joined body 31, the fourth joined body 34, and the fifth joined body 35 are supported. An insulating film constituting the side buffer layer is formed. Since the insulating film i corresponding to the first bonded body 31 to the fifth bonded body 35 is formed with a contact hole at the time of patterning, the insulating film i is formed in a substantially annular shape.

  Next, as shown in FIG. 13, a barrier metal film b constituting the support side buffer layer is formed on the second substrate 13 and the insulating film i by a generally known method such as CVD.

  Next, as shown in FIG. 14, a mask resist (not shown) is formed on the barrier metal film b, and etching is performed to pattern the barrier metal film b. The patterning by etching of the barrier metal film b is preferably dry etching. By this step, all the barrier metal film b on the insulating film 96i is removed in the frame region A. In the conductive region B, a barrier metal film 92b constituting the second support side buffer layer 92 is formed. In addition, an insulating film 93i that constitutes the third support-side buffer layer 93 is formed in the electrode region C, and at the same time, supports corresponding to the first joined body 31, the fourth joined body 34, and the fifth joined body 35 are supported. A barrier metal film constituting the side buffer layer is formed. Barrier metal films corresponding to the first to fifth joined bodies 31 to 35 are formed in a substantially cylindrical shape.

  The process described with reference to FIGS. 11 to 14 corresponds to forming the support-side buffer layer described in the claims.

  Next, as shown in FIG. 15, a metal film p (for example, aluminum) serving as a constituent material of the pad is formed by a general method such as sputtering or PVD so as to cover the second substrate 13 and the support side buffer layer. To do.

  Next, as shown in FIG. 16, by patterning the metal film p by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film, the first support side pad 31a to the sixth support side pad 36a. Are selectively formed. Etching for forming the pads 31a to 36a is preferably wet etching.

  The process described with reference to FIGS. 15 and 16 corresponds to forming the support side pad on the first surface 10a described in the claims.

  Next, although not shown, the groove 14 and the slit 50 are formed in the second substrate 13 by reactive ion etching or the like using a mask such as a resist or an oxide film. Thus, the first substrate 10 is prepared in which the movable portion 20 is formed and the peripheral portion 30 is partitioned into the island portion 30a and the base portion 30b, or the outer peripheral portion 30c and the inner peripheral portion 30d.

  In a step different from the steps described with reference to FIGS. 10 to 16, a bonded substrate 41 is prepared as shown in FIG. Then, although not shown, a mask resist (not shown) is formed on the bonded substrate 41 and etching or the like is performed to form the recess 16 in the bonded substrate 41. Then, an insulating film 42 is formed on the entire surface of the bonded substrate 41 by thermal oxidation or the like.

  The insulating film 42 formed on the second surface 40a side corresponds to the cap-side buffer layer in the present embodiment, and the step described with reference to FIG. 17 is the cap-side buffer layer described in the claims. It corresponds to forming.

  Next, as shown in FIG. 18, a metal film (aluminum) is formed on a portion of the insulating film 42 facing the support substrate 10. Then, the first fixed electrode 61 and the second fixed electrode 62 are formed by patterning the metal film by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film. In this step, the first cap side pad 31b to the sixth cap side pad 36b are selectively formed. Further, the relay wiring 63 is formed in this step. The sixth cap side pad 36b belonging to the frame region A has a frame shape corresponding to the sixth support side pad 36a. On the other hand, the second cap side pad 32b belonging to the conduction region B is formed in a cylindrical shape. The first cap side pad 31b, the third cap side pad 33b, the fourth cap side pad, and the fifth cap side pad that belong to the electrode region C and are connected to the through electrode 70 later are formed in a substantially annular shape.

  The process described with reference to FIG. 18 corresponds to forming a cap-side pad on the second surface 40a described in the claims.

  Next, as shown in FIG. 19, the support substrate 10 and the cap substrate 40 are bonded. Specifically, alignment is performed by an infrared microscope or the like using an appropriately formed alignment mark, and the first support side pad 31a to the sixth support side pad 36a formed on the support substrate 10 and the cap substrate 40 are formed. The first cap side pad 31b to the sixth cap side pad 36b thus formed are metal-bonded at 300 to 500 ° C. As a result, the space between the support substrate 10 and the cap substrate 40 is sealed by the sixth joined body 36 to form the cavity 80, and the frame portion 22, the first fixed electrode 61, and the second fixed electrode 62 are in the cavity 80. Hermetically sealed.

  The process described with reference to FIG. 19 corresponds to diffusion bonding or thermocompression bonding of the support side pad and the cap side pad described in the claims.

  Next, as shown in FIG. 20, the insulating film 42 and the bonded substrate 41 are ground from the side opposite to the supporting substrate 10 side, thereby removing the insulating film 42 on the side opposite to the supporting substrate 10 side and the bonded substrate 41. Thin out.

  Next, as shown in FIG. 21, by removing the bonded substrate 41 and the insulating film 42 at locations corresponding to the first bonded body 31, the third bonded body 33, the fourth bonded body 34, and the fifth bonded body 35. Four through holes 41a are formed. Then, an insulating film 41b such as TEOS is formed on the wall surface of each through hole 41a. At this time, the insulating film 43 is composed of an insulating film formed on the side of the bonded substrate 41 opposite to the support substrate 10 side. That is, the insulating film 43 and the insulating film 41b are formed in the same process. Thereafter, the insulating film 41b formed at the bottom of each through hole 41a is removed, and the first joined body 31, the third joined body 31, the fourth joined body 34, and the fifth joined body 35 are placed in each through hole 41a. Expose.

  Next, as shown in FIG. 22, each through electrode 70 is formed by disposing a metal film in each through hole 41 a by sputtering, vapor deposition, or the like. Specifically, the first through electrode 71 is formed in the through hole 41 a corresponding to the first joined body 31. The second through electrode 72 is formed in the through hole 41 a corresponding to the third joined body 33. A third through electrode is formed in the through hole 41 a corresponding to the fourth joined body 34. A fourth through electrode is formed in the through hole 41 a corresponding to the fifth joined body 35. Thereafter, the metal film on the insulating film 43 is patterned to form the land portion 70a.

  The inertial sensor 100 can be manufactured through the steps described above. As described above, since the barrier metal film b is not always necessary in the conductive region B and the electrode region C, the step of forming the barrier metal film b described with reference to FIGS. 13 and 14 may be omitted. good.

  In the above description, the manufacturing method of the inertial sensor 100 that detects the acceleration applied in the z-axis direction has been described. However, a sensing unit that detects the acceleration applied in the direction along the xy plane is provided in the same inertial sensor 100. You may do it. In the above description, the manufacturing method of one acceleration sensor has been described. However, the wafer-like support substrate 10 and the cap substrate 40 may be prepared, and after dicing and cutting, the wafer may be divided into chips.

  Next, the effect of the inertial sensor 100 according to the present embodiment will be described.

  In this inertial sensor 100, each of the joined bodies 31 to 36 made of metal, the second substrate 13 made of silicon, and the bonded substrate 41 are joined to each other via a support side buffer layer and a cap side buffer layer, respectively. . In other words, the metal constituting the bonded bodies 31 to 36 and silicon are not in contact with each other. For this reason, mutual thermal diffusion between the metal and silicon can be suppressed even under high temperature and high pressure when the support substrate 10 and the cap substrate 40 are bonded as described with reference to FIG. That is, alloy spikes can be suppressed and a decrease in mechanical strength can be suppressed.

  In particular, in the present embodiment, in the conduction region B and the electrode region C, contact holes are formed in the support-side buffer layer due to the necessity of electrical connection between the second joined body 32 to the fifth joined body 35 and the second substrate 13. However, the barrier metal layers 92b and 93b are formed so as to cover the support substrate 13 exposed by the formation of the contact holes. For this reason, also in the conduction | electrical_connection area | region B and the electrode area | region C, the contact with the metal which comprises the joined bodies 32-35 and silicon | silicone can be prevented, and generation | occurrence | production of an alloy spike can be suppressed.

  In addition, the joined bodies 32 and 33 in the present embodiment are formed so as to be located inside the outermost contour lines of the support-side buffer layers 92 and 93 that are in contact with each other when viewed from the front in the z-axis direction. . In other words, the support side buffer layers 92 and 93 are formed so as to enclose the second support side pad 32a and the third support side pad 33b, respectively, when viewed from the front in the z-axis direction. Since the support side pads 31a to 36a are made of metal, the support side pads 31a to 36a have spreadability, and are deformed when the support substrate 10 and the cap substrate 40 are bonded to each other. The bonded bodies 32 and 33 contact each other. Since the support side buffer layers 92 and 93 are formed so as to be located inside the outermost contour line, the support substrate 13 exceeds the support side buffer layers 92 and 93 even if the joined bodies 32 and 33 are deformed. To be suppressed. Therefore, an unexpected alloy spike can be suppressed.

  Further, in the present embodiment, in each of the regions A to C, when viewed from the front in the z-axis direction, at least a part of the support side buffer layer (92, 93, 96) and the cap side buffer layer (that is, the insulating film 43). ) And at least a part of the joint surface between the support side pads (92a, 93a, 96a) and the cap side pads (92b, 93b, 96b) overlap. The portions where the support side pads (92a, 93a, 96a) and the cap side pads (92b, 93b, 96b) are in contact with each other are formed on the support substrate 10 and the cap substrate 40 during the bonding process or when used as a sensor. It becomes a transmission path of the force in the working z-axis direction. That is, when viewed from the front in the z-axis direction, mechanical strength is required for a portion that overlaps the joint surface between the support side pads (92a, 93a, 96a) and the cap side pads (92b, 93b, 96b). . In the present embodiment, the support-side buffer layer and the cap-side buffer layer overlap this joint surface, and the alloying of silicon and the bonded body is suppressed, so that the support-side buffer layer and the cap-side buffer layer are The mechanical strength can be improved as compared with a structure that is not formed.

(Second Embodiment)
In the first embodiment, the example in which the through electrode 70 is formed on the cap substrate 40 side has been described. However, in the second embodiment, as illustrated in FIG. 23, the inertia in which the through electrode 70 is formed on the support substrate 10 side. The sensor 110 will be described.

  The inertial sensor 110 has substantially the same configuration as that of the inertial sensor 100 of the first embodiment except for the position where the through electrode 70 is formed and the joined bodies 31 to 36 derived from the difference in the position of the through electrode 70. . The through electrode 70 in the present embodiment is formed in a mirror-symmetrical position with respect to the through electrode 70 in the first embodiment, with the xy plane as a symmetry plane. As shown in FIG. 23, a fifth through electrode 75 is formed corresponding to the first through electrode 71, and a sixth through electrode 76 is formed corresponding to the second through electrode 72. In addition, although the penetration electrode 70 corresponding to the 3rd penetration electrode and the 4th penetration electrode is also formed, illustration is abbreviate | omitted.

  The fifth through electrode 75 and the sixth through electrode 76 are formed so as to penetrate the first substrate 11 and the insulating film 12 in the support substrate 10. The through electrode 70 in the present embodiment is formed in the through hole 11a penetrating the first substrate 11 and the insulating film 12 via the insulating film 11b. The insulating film 11b is connected to the insulating film 12 on the inner wall surface of the through hole 11a to form an integral insulating film. The through electrode 70 is formed along the inner wall surface of the through hole 11a.

  As shown in FIG. 23, the fifth through electrode 75 passes through the insulating film 12 and reaches the first bonded body 31. That is, the fifth through electrode 75 is electrically connected to the movable unit 20 via the first joined body 31, the relay wiring 63, and the second joined body 32. The sixth through electrode 76 penetrates the insulating film 12 and reaches the second substrate 13. The second substrate 13 is electrically connected to the bonded substrate 41 via the third bonded body 33. The remaining two through electrodes 70 (not shown) are electrically connected to the first fixed electrode 61 and the second fixed electrode 62, respectively.

  Also in the inertial sensor 110, the joined bodies 31 to 36 are classified into three regions. Two of the three types are the frame region A and the conduction region B similar to those in the first embodiment. Since the frame region A and the conduction region B have the same structure as that of the first embodiment, the description thereof is omitted.

  The remaining one of the three types is the interlayer connection region D. The third bonded body 33 belongs to the interlayer connection region D. As shown in FIGS. 23 and 24, the third joined body 33 in the inertial sensor 110 is electrically connected by mediating between the peripheral portion 30 of the second substrate 13 and the bonded substrate 41, and the peripheral portion. 30 and a bonded substrate 41 for holding the bonded substrate 41 at the same potential. The peripheral portion 30 is connected to the sixth through electrode 76. For example, if the sixth through electrode 76 is set to the ground potential, the bonded substrate 41 and the peripheral portion 30 can be held at the ground potential.

  In the third bonded body 33 in the present embodiment, two opposing pads are bonded to each other and integrated. Specifically, as shown in FIG. 24, the third bonded body 33 includes a third support-side pad 33a formed on the support substrate 10 (second substrate 13) side and a third support-side pad 33a formed on the cap substrate 40 side. The three cap side pads 33b are integrally joined to each other by diffusion bonding or thermocompression bonding with the opposing surface as a bonding surface.

  The third support-side pad 33a is bonded to the second substrate 13 in the support substrate 10 and thus the peripheral portion 30 via the barrier metal film 93b. The main component of the third support side pad 33a is aluminum, and the main component of the second substrate 13 is silicon, but these are not in direct contact with each other, and are mutually connected via a barrier metal film 93b made of titanium nitride or the like. It is in a joined state.

  On the other hand, the third cap side pad 33b is joined to the cap substrate 40 via an insulating film 42 formed on the second surface 40a side of the cap substrate 40. The insulating film 42 has a contact hole 42h penetrating in a cylindrical shape. A contact portion 33c made of the same material as that of the third cap side pad 33b is formed in the contact hole 42h so as to fill the contact hole 42h. The contact portion 33c is formed integrally with the third cap side pad 33b on one side of the opening of the contact hole 42h, and is in contact with the bonded substrate 41 on the other side of the opening. That is, the third cap side pad 33b is electrically connected to the bonded substrate board 41 through the contact portion 33c.

  As in the case of the first embodiment, the barrier metal film 93b corresponds to the support-side buffer layer described in the claims. However, as shown in FIG. 25, an aspect including the insulating film 93i may be employed. it can. In the example shown in FIG. 25, the third support side pad 33 a is bonded to the support substrate 10 via an insulating film 93 i formed on the first surface 10 a side of the support substrate 10. The insulating film 93i has a contact hole 93h penetrating in a cylindrical shape. A barrier metal film 93b is interposed between the third support side pad 33a and the insulating film 93i. The barrier metal film 93b is also disposed in the contact hole 93h, and a contact portion 33c made of the same material as that of the third support side pad 33a is formed in the contact hole 93h so as to fill the contact hole 93h.

  In the form shown in FIG. 24, the insulating film 42 corresponds to the cap-side buffer layer described in the claims. However, as shown in FIG. 25, an aspect including the barrier metal film 42i can also be adopted. . In this embodiment, the barrier metal film 42 b is interposed between the third cap side pad 33 b and the insulating film 42. The barrier metal film 42b is also disposed in the contact hole 42h.

  In the inertial sensor shown in FIG. 25, the barrier metal films 42b and 93b may not be provided. However, it is preferable to provide the barrier metal films 42b and 93b from the viewpoint that the bonded substrate 41 and the second substrate 13 and the third bonded body 33 are not in direct contact with each other.

  Similarly to the first embodiment, in the second embodiment, when viewed from the front in the z-axis direction, mechanical strength is required for a portion that overlaps the joint surface between the support side pad 93a and the cap side pad 93b. The In this embodiment, the contact hole 33b in the support side buffer layer does not overlap with the cap side buffer layer, and the contact hole 33h of the cap side buffer layer does not overlap with the support side buffer layer. Thereby, the area where the bonding surface of the support side pad 93a and the cap side pad 93b overlaps the support side buffer layer and the cap side buffer layer can be made as large as possible, and the alloy of silicon and the bonded body The mechanical strength can be improved while suppressing the formation.

  If the size in the x-axis direction is limited, as shown in FIG. 25, it may not be possible to adopt a configuration in which the contact hole 33b in the support-side buffer layer and the contact hole 33h in the cap-side buffer layer are displaced in the x-axis direction. . In such a case, as shown in FIG. 26, in the z-axis direction, the contact hole 33b in the support side buffer layer and the contact hole 33h in the cap side buffer layer may overlap each other. In the region excluding the portion where the contact hole 33h overlaps, the bonded body 33 and the insulating films 42 and 93i overlap, so that the mechanical strength can be improved while suppressing the alloying of silicon and the bonded body. In particular, if the contact hole 33b in the support side buffer layer and the contact hole 33h in the cap side buffer layer are completely overlapped, the area where the joined body 33 and the insulating films 42 and 93i overlap is maximized. And mechanical strength can be secured more efficiently.

  In the present embodiment, the conduction region B and the interlayer connection region D have been described separately. However, the joined body in the conduction region B and the interlayer connection region D is interposed between different conductive layers and contributes to electrical conduction between layers. Therefore, both are concepts included in the conduction region described in the claims.

(Other embodiments)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In each of the above-described embodiments, the example in which aluminum is used for the joined bodies 31 to 36 and the through electrode 70 has been described, but a metal including gold or copper may be used. For each insulating film, a silicon oxide film or a nitride film can be employed. Further, for each barrier metal film, it is preferable to employ a metal having an alloy resistance to aluminum or copper. For example, a metal including at least one of titanium, titanium nitride, tantalum, and tantalum nitride may be employed. it can.

  The bonded bodies 31 to 36 preferably have an antioxidant film formed on the surface. The anti-oxidation film may be a film having reducibility with respect to the surface oxidation of the joined bodies 31 to 36. For example, a titanium thin film can be employed. The antioxidant film can be formed on the support-side pad by patterning each support-side pad and then depositing titanium, for example. Moreover, after patterning each cap side pad, the antioxidant film | membrane in a cap side pad can be formed by the method of vapor-depositing titanium etc., for example.

DESCRIPTION OF SYMBOLS 10 ... Support substrate, 11 ... 1st board | substrate, 12 ... Insulating film, 13 ... 2nd board | substrate, 20 ... Movable part, 30 ... Peripheral part, 31 ... 1st joined body, 32 ... 2nd joined body, 36 ... 6th Bonded body, 40 ... cap substrate, 41 ... bonded substrate, 63 ... relay wiring, 70 ... through electrode, 80 ... cavity

Claims (22)

A support substrate (10) including a layer mainly composed of a semiconductor and having a first surface (10a);
A cap substrate (40) that includes a layer mainly composed of a semiconductor, has a second surface (40a), and is bonded to the support substrate in a state where the second surface faces the first surface;
Support side pads (31a to 36a) made of metal and bonded to the first surface of the support substrate;
Cap side pads (31b to 36b) made of metal, bonded to the second surface of the cap substrate and bonded to the opposing support side pads to form a bonded body (31 to 36),
A semiconductor device in which an airtight cavity (80) is formed between the support substrate and the cap substrate, and a sensing unit that outputs a sensor signal corresponding to a physical quantity is disposed in the cavity,
According to the formation position, the joined body
A frame region (A) that bears the mechanical strength of bonding between the support substrate and the cap substrate;
Conductive regions (B, C, D) responsible for electrical connection between layers,
Including at least two connection areas,
The joined body is provided with an insulating film (92i, 93i, 96i) and / or a barrier metal film (92b, 93b, 96b) or a support side buffer layer (92, 93, 96) between the supporting substrate and the support substrate. And joined together
A semiconductor device bonded to the cap substrate via a cap-side buffer layer including an insulating film (42), a barrier metal film (42b), or both. When the insulating film is interposed between the supporting substrate or the cap substrate and the bonded body as the supporting buffer layer and the cap buffer layer, the bonded body in the conduction region is,
The contact hole (92h, 93, 96h, 42h) provided through the insulating film is filled and has a contact portion (32c, 33c) formed integrally with the joined body, so that the support substrate or The semiconductor device according to claim 1, wherein the cap substrate and the joined body are electrically connected.   The support-side buffer layer and / or the cap-side buffer layer include a bonding surface between the insulating film in which the contact hole is formed and the bonded body, and a bonding between the contact portion and the support substrate or the cap substrate. The semiconductor device according to claim 2, wherein the barrier metal film is provided on a surface. When viewed from the front toward the first surface,
The at least part of the support side buffer layer, the at least part of the cap side buffer layer, and at least a part of the joint surface between the support side pad and the cap side pad overlap each other. 4. The semiconductor device according to any one of items 3.   5. The semiconductor device according to claim 1, wherein the support-side buffer layer is formed so as to include the support-side pad when viewed from the front toward the first surface. 6.   The semiconductor device according to claim 1, wherein the cap-side buffer layer is formed so as to include the cap-side pad when viewed from the front toward the first surface.   The semiconductor device according to claim 1, wherein the support-side pad and / or the cap-side pad have an antioxidant film that covers a surface thereof and suppresses oxidation.   The semiconductor device according to claim 1, wherein the support side pad and the cap side pad include aluminum or copper.   The semiconductor device according to claim 8, wherein the support side pad and / or the cap side pad have an anti-oxidation film that covers a surface thereof and suppresses oxidation, and the anti-oxidation film contains titanium.   The semiconductor device according to claim 1, wherein the premise barrier metal film includes at least one of titanium, titanium nitride, tantalum, and tantalum nitride. A support substrate (10) including a layer mainly composed of a semiconductor and having a first surface (10a);
A cap substrate (40) that includes a layer mainly composed of a semiconductor, has a second surface (40a), and is bonded to the support substrate in a state where the second surface faces the first surface;
Support side pads (31a to 36a) made of metal and bonded to the first surface of the support substrate;
Cap side pads (31b to 36b) made of metal, bonded to the second surface of the cap substrate and bonded to the opposing support side pads to form a bonded body (31 to 36),
A method of manufacturing a semiconductor device in which an airtight cavity (80) is formed between the support substrate and the cap substrate, and a sensing unit that outputs a sensor signal corresponding to a physical quantity is disposed in the cavity.
According to the formation position, the joined body
A frame region (A) that bears the mechanical strength of bonding between the support substrate and the cap substrate;
Conductive regions (B, C, D) responsible for electrical connection between layers,
Including at least two connection areas,
Forming the support side pad on the first surface of the support substrate;
Forming the cap-side pad on the second surface of the cap substrate;
Diffusion bonding or thermocompression bonding of the support side pad and the cap side pad,
Before forming the support-side pad on the support substrate, an insulating film (92i, 93i, 96i) or a barrier metal film (92b, 93b, 96b) or the same is formed between the support substrate and the support-side pad. Forming a support side buffer layer (92, 93, 96) including both;
Before forming the cap-side pad on the cap substrate, a cap-side buffer layer including an insulating film (42) and / or a barrier metal film (42b) is provided between the support substrate and the support-side pad. Forming a semiconductor device. In the conduction region, when an insulating film is interposed between the support substrate and the bonded body as the support-side buffer layer,
Forming contact holes (92h, 93, 96h) in the insulating film before forming the support-side pads on the first surface of the support substrate;
The method for manufacturing a semiconductor device according to claim 11, further comprising: forming contact portions (32 c, 33 c) integrally with the support side pad in the contact hole when forming the support side pad.   Before forming the contact portion, an inner wall surface of the contact hole, a surface opposite to a bonding surface of the insulating film with the support substrate, and a surface of the support substrate exposed by forming the contact hole, The method for manufacturing a semiconductor device according to claim 12, further comprising forming a barrier metal film so as to cover the film. In the conduction region, when an insulating film is interposed between the cap substrate and the bonded body as the cap-side buffer layer,
Forming a contact hole (42h) in the insulating film before forming the cap-side pad on the second surface of the cap substrate,
14. The semiconductor device according to claim 11, further comprising: forming a contact portion (33 c) integrally with the cap-side pad in the contact hole when forming the cap-side pad. Manufacturing method.   Before forming the contact portion, an inner wall surface of the contact hole, a surface opposite to a bonding surface of the insulating film with the cap substrate, and a surface of the cap substrate exposed by forming the contact hole, The method of manufacturing a semiconductor device according to claim 14, further comprising: forming a barrier metal film so as to cover the film. When viewed from the front toward the first surface,
The at least part of the support side buffer layer, the at least part of the cap side buffer layer, and at least a part of the joint surface between the support side pad and the cap side pad overlap each other. 16. A method for manufacturing a semiconductor device according to any one of 15 above. When the support side buffer layer includes the barrier metal film,
The method for manufacturing a semiconductor device according to claim 11, wherein the barrier metal film is formed so as to include the support-side pad when viewed from the front toward the first surface. . When the cap side buffer includes the barrier metal film,
The method of manufacturing a semiconductor device according to claim 11, wherein the barrier metal film is formed so as to include the cap-side pad when viewed from the front toward the first surface. .   19. The method of manufacturing a semiconductor device according to claim 11, wherein the support-side pad and / or the cap-side pad have an antioxidant film that covers a surface thereof and suppresses oxidation.   The method of manufacturing a semiconductor device according to claim 11, wherein the support side pad and the cap side pad include aluminum or copper.   21. The manufacturing method of a semiconductor device according to claim 20, wherein the support-side pad and / or the cap-side pad have an antioxidant film that covers a surface thereof and suppresses oxidation, and the antioxidant film contains titanium. Method.   The semiconductor device manufacturing method according to claim 11, wherein the premise barrier metal film includes at least one of titanium, titanium nitride, tantalum, and tantalum nitride.

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