WO2018003353A1 - Semiconductor device - Google Patents

Abstract

A semiconductor device according to the present invention includes: a support substrate (10) having a first face (10a); a cap substrate (40) having a second face (40a) and joined with the support substrate; a sensing section (20, 30, 60) disposed in a cavity (80) between the support substrate and the cap substrate; a penetrating electrode (70) formed to penetrate the support substrate or the cap substrate in the thickness direction thereof; a first pad section (31) electrically connected to the penetrating electrode between the first face and the second face; and a relay wire (63). The sensing section has a second pad section (32) having the same potential as the sensing section. When the support substrate is viewed from the thickness direction, the first pad section and the second pad section are deviated from each other. The relay wire electrically connects the first pad section and the second pad section with each other.

Description

Semiconductor device Cross-reference of related applications

This application is based on Japanese Patent Application No. 2016-131710 filed on July 1, 2016 and Japanese Patent Application No. 2016-131708 filed on July 1, 2016. The description is incorporated.

The present disclosure 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.

For example, in the physical quantity sensor described in Patent Document 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.

And 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, the change in electrostatic capacitance formed by the semiconductor layer and the fixed electrode is calculated based on the potential difference between the potential of the semiconductor layer and the potential of the fixed electrode. The potential of the semiconductor layer can be detected by contacting and electrically connecting a pad portion provided on the anchor and a through electrode provided on the cap substrate at a position facing the pad portion.

In such a configuration, the through electrode for taking out the potential of the semiconductor layer is located immediately above the anchor. The through electrode is larger in size than the pad portion provided on the anchor, and the thermal stress due to thermal expansion or contraction with respect to temperature change is also relatively large, which causes the movable portion to be deformed by the thermal stress. When deformation such as warpage occurs in the movable part, the distance between the movable part and the fixed electrode changes, so that the capacitance changes. That is, the capacitance is easily affected by thermal noise.

Further, in the physical quantity sensor described in Patent Document 1, an electrode for taking out the potential of the fixed electrode and the semiconductor layer to the outside is provided as a through electrode (TSV). The through electrode is formed in a through hole that penetrates the cap substrate to which the fixed electrode is bonded.

When forming through holes for TSV in the cap substrate, it is preferable that the cap substrate is made as thin as possible from the viewpoint of workability of the holes and size reduction of the sensor. On the other hand, if the cap substrate is too thin, the cap substrate may be distorted in accordance with changes in the surrounding environment such as temperature and stress.

Since the fixed electrode is formed on the cap substrate, there is a risk that the capacitance formed by the semiconductor layer and the fixed electrode may change when thermal strain or stress strain occurs. That is, there is a risk that noise superimposed on acceleration increases.

This disclosure is intended to provide a semiconductor device that includes a sensing unit that outputs a sensor signal corresponding to a physical quantity in a cavity and can reduce noise caused by temperature.

It is another object of the present disclosure to provide a semiconductor device that can suppress noise due to substrate distortion in a semiconductor device including a sensing unit that outputs a sensor signal corresponding to a physical quantity in a cavity.

In the first aspect of the present disclosure, the semiconductor device has a support substrate having a first surface and a second surface, and the second surface is bonded to the support substrate in a state of facing the first surface. A cap substrate, a sensing unit that is disposed in an airtight cavity formed between the support substrate and the cap substrate, and outputs a sensor signal corresponding to a physical quantity, and a thickness of the support substrate or the cap substrate A through electrode formed penetrating in a direction, a first pad portion formed between the first surface and the second surface and electrically connected to a tip of the through electrode, and a relay wiring Prepare. The sensing unit includes a second pad unit that has the same potential as the sensing unit. When the support substrate is viewed from the thickness direction, the first pad portion and the second pad portion are arranged to be shifted from each other. The relay wiring electrically connects the first pad part and the second pad part to each other.

According to the above semiconductor device, the first pad portion connected to the through electrode and the second pad portion connected to the sensing portion are not directly joined but connected via the relay wiring. For this reason, even when the through electrode expands or contracts due to the temperature, it is possible to suppress the thermal stress from being directly transmitted to the second pad portion and thus the sensing portion. Therefore, noise caused by temperature superimposed on the sensor signal output from the sensing unit can be reduced.

In the second aspect of the present disclosure, the semiconductor device includes a support substrate having a first surface and a second surface, and the second surface is bonded to the support substrate in a state of facing the first surface. A cap substrate, a fixed electrode disposed between the support substrate and the cap substrate, fixed to the second surface in an airtight cavity, and formed to face the fixed electrode in the cavity. A sensing portion that forms a capacitance and outputs a sensor signal according to a change in the capacitance, and a penetration that is formed through the support substrate and electrically connects the inside and outside of the cavity to each other An electrode.

According to the above semiconductor device, the through electrode is formed on the support substrate separate from the cap substrate on which the fixed electrode is formed. That is, it is not necessary to form a through hole in the cap substrate. Therefore, the plate thickness of the cap substrate can be arbitrarily set without depending on the specification of the through electrode. As a result, the plate | board thickness of a cap board | substrate can be set so that the superimposition of the noise to a sensor signal by the distortion resulting from a heat | fever and stress may be suppressed.

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. The drawing
FIG. 1 is a diagram showing the configuration of the inertial sensor according to the first embodiment, and is a cross-sectional view taken along the line II shown in FIG. FIG. 2 is a top view showing the configuration of the inertial sensor according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a process of preparing a first substrate and forming an insulating film, FIG. 4 is a cross-sectional view showing a step of forming a recess, FIG. 5 is a cross-sectional view showing a process of forming the second substrate, FIG. 6 is a cross-sectional view showing a process of forming each pad portion. FIG. 7 is a cross-sectional view showing a step of forming a groove and a slit, FIG. 8 is a cross-sectional view illustrating a process of forming a bonded substrate and an insulating film, FIG. 9 is a cross-sectional view showing a step of forming a recess, FIG. 10 is a cross-sectional view showing a process of forming each pad portion and relay wiring, FIG. 11 is a cross-sectional view illustrating a process of bonding the support substrate and the cap substrate, FIG. 12 is a cross-sectional view showing a process of thinning the bonded substrate, FIG. 13 is a cross-sectional view illustrating a process of forming a through hole in a bonded substrate; FIG. 14 is a cross-sectional view showing a process of forming a through electrode, FIG. 15 is a diagram showing a configuration of the inertial sensor according to the second embodiment, and is a cross-sectional view taken along line XV-XV shown in FIG. FIG. 16 is a top view showing the configuration of the inertial sensor according to the second embodiment. FIG. 17 is a cross-sectional view showing the configuration of the inertial sensor according to the third embodiment. 18 is a diagram showing a configuration of the inertial sensor according to the fourth embodiment, and is a cross-sectional view taken along line XVIII-XVIII shown in FIG. FIG. 19 is a top view showing the configuration of the inertial sensor (second substrate) according to the fourth embodiment. FIG. 20 is a cross-sectional view illustrating a process of preparing a first substrate and forming an insulating film, FIG. 21 is a cross-sectional view showing a process of forming the second substrate, FIG. 22 is a cross-sectional view showing a step of forming a part of each joined body, FIG. 23 is a cross-sectional view showing a step of forming a groove and a slit, FIG. 24 is a cross-sectional view illustrating a process of forming a bonded substrate and an insulating film and forming a cap substrate side contact; FIG. 25 is a cross-sectional view showing a process of forming a part of each joined body and a relay wiring, FIG. 26 is a cross-sectional view showing a process of bonding the support substrate and the cap substrate, FIG. 27 is a cross-sectional view showing a process of forming a through-hole while thinning the bonded substrate and the support substrate, FIG. 28 is a cross-sectional view showing a step of forming an insulating film in the through hole, FIG. 29 is a cross-sectional view showing a step of forming a support substrate side contact.

(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 the present 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. FIG. 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 12. It is composed of a surface on the side opposite to the 12 side. The first substrate 11 is made of silicon or the like, the insulating film 12 is made of an oxide film or a nitride film, and the second substrate 13 is made of polysilicon 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 not formed on 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 on the first substrate 11 by connecting the torsion beam 23 to the anchor portion 24 on which the insulating film 12 is supported.

Here, the definition of the direction in the present embodiment will be described. 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 serving as a rotation axis that becomes the rotation center of the movable portion 20 when an acceleration in the z-axis direction is applied. 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, the first pad portion 31, the second pad portion 32, the third pad portion 33, the fourth pad portion 34, and the fifth pad portion 35 are provided on the first surface 10 a of the support substrate 10, that is, the surface of the second substrate 13. And an airtight frame 36 are formed. In the present embodiment, the pad portions 31 to 35 and the airtight frame 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 pad portion 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 pad portion 32 is formed on the anchor portion 24 and is electrically connected to the movable portion 20. The third pad portion 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 pad portion 34 is formed in the peripheral portion 30 and connected to a third through electrode (not shown) on the second surface 40a. The fifth pad portion 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 pad portion 31, the third pad portion 33, the fourth pad portion 34, and the fifth pad portion 35 are respectively the first through electrode 71, the second through electrode 72, the third through electrode, and the fourth. It has the same potential as the through electrode, and can be output to the outside through these electrodes. Conversely, if a voltage is applied to these electrodes, the corresponding pad portion can be brought to a desired potential.

Further, the first pad portion 31 and the second pad portion 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 airtight frame 36 is formed in a frame shape so as to surround the movable portion 20 (groove portion 14). Since the hermetic frame 36 is formed between the support substrate 10 and the cap substrate 40, the region surrounded by the hermetic frame 36, the support substrate 10 and the cap substrate 40 is an airtight space isolated from the outside. ing. A cavity corresponds to the isolation space. Hereinafter, this isolation space is referred to as a cavity 80. A spacer that is outside the hermetic frame 35 and is sandwiched between the support substrate 10 and the cap substrate 40 may be separately formed. The spacer maintains the distance between the support substrate 10 and the cap substrate 40, and can be composed of an insulating film such as an oxide film.

The second substrate 13 in the support substrate 10 has a plurality of slits 50 in the outer peripheral portion 30 as shown in FIGS. 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 pad portion 31, the third pad portion 33, the fourth pad portion 34, and the fifth pad portion 35. ing. As shown in FIG. 2, the first type slit 51 surrounding the contact portion with the first pad portion 31 is annular, and the region surrounded by the slit is hereinafter referred to as a joint portion 30a. That is, the peripheral portion 30 is partitioned by the first type slit 51 into a joint portion 30a and a base body portion 30b excluding the joint 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 joint part 30 a and the base part 30 b are concepts including the first substrate 11 and the insulating film 12.

Similarly to the first pad portion 31, a first type slit 51 is formed so as to surround a contact portion of the second substrate 13 with the third pad portion 33. The first type slit 51 corresponding to the third pad portion 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 pad portion 34 of the second substrate 13, and the first type slit 51 is set so as to surround the contact portion with the fifth pad portion 35. Is formed. The first type slit 51 corresponding to the fourth pad portion 34 and the fifth pad portion 35 has an annular shape, and divides the joint 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 contact portions of the peripheral portion 30 with the pad portions 31, 33 to 35 inside. Yes. The second type slit 52 in this embodiment is formed in a rectangular shape along the airtight frame 36 in the frame where the airtight frame 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 where the airtight frame 36 is joined. On the other hand, the inner peripheral part 30d is an area including the movable part 20 and the above-described joint 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.

The first fixed electrode 61 and the second fixed electrode 62 are formed on the second surface 40a 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 22a in the frame portion 22 when viewed from the front in 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 with the second portion 22b 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 made of aluminum, for example. Further, the first fixed electrode 61 and the second fixed electrode 62 have the same planar shape, and form an equal capacitance between the first and second portions 22a and 22b in a state where no acceleration is applied. Yes.

Furthermore, a 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 pad portion 31 and the second pad portion 32. With the relay wiring 63, the second pad portion 32 and the first pad portion 31, and thus the first through electrode 71 can be set to 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.

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, a 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 the through holes 41a penetrating the bonded substrate 41 and the insulating film 42 via the 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 pad portion 31. That is, the first through electrode 71 is electrically connected to the movable portion 20 via the first pad portion 31, the relay wiring 63, and the second pad portion 32. The second through electrode 72 penetrates the insulating film 42 and reaches the third pad portion 33. A third through electrode and a fourth through electrode (not shown) penetrate the insulating film 42 and reach the fourth pad portion 34 and the fifth pad portion 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 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.

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

First, as shown in FIG. 3, a first substrate 11 constituting a support substrate 10 is prepared, and an insulating film 12 is formed on the first substrate 11 by a generally known method such as CVD or thermal oxidation.

Next, as shown in FIG. 4, a mask resist (not shown) is formed on the insulating film 12 and etching or the like is performed to form a recess 15 in the first substrate 11.

Next, as shown in FIG. 5, the insulating film 12 and the second substrate 13 are joined to form the support substrate 10. 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 an Ar ion beam to activate the bonding surfaces of the insulating film 12 and the second substrate 13. Then, alignment is performed by an infrared microscope or the like 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. 6, a metal film (aluminum) is formed on the first surface 10a of the support substrate 10 by a CVD method or the like. Then, 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, the first pad portion 31 to the fifth pad portion 35 and a part of the airtight frame 36 are A metal layer is selectively formed.

Next, as shown in FIG. 7, the groove 14 and the slit 50 are formed in the second substrate 13 by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film. Thereby, the movable substrate 20 is formed, and the first substrate 10 in which the peripheral portion 30 is partitioned into the joint portion 30a and the base portion 30b, or the outer peripheral portion 30c and the inner peripheral portion 30d is prepared.

3 to 7, a bonded substrate 41 is prepared as shown in FIG. 8, and an insulating film 42 is formed on the entire surface of the bonded substrate 41 by thermal oxidation or the like.

Next, as shown in FIG. 9, a mask resist (not shown) is formed on the insulating film 42 and etching or the like is performed to form the recess 16 in the bonded substrate 41.

Next, as shown in FIG. 10, 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 pad portion 31 to the fifth pad portion 35 and the metal layer that becomes the remaining portion of the airtight frame 36 are selectively formed. Further, the relay wiring 63 is formed in this step. In FIG. 10, the first pad portion 31, the second pad portion 32, and the relay wiring 63 are integrally illustrated.

Next, as shown in FIG. 11, the support substrate 10 and the cap substrate 40 are joined. Specifically, alignment is performed with an infrared microscope or the like using appropriately formed alignment marks, the first pad portion 31 to the fifth pad portion 35 and the airtight frame 36 formed on the support substrate 10, and the cap substrate 40. The first pad portion 31 to the fifth pad portion 35 and the airtight frame 36 formed in the above 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 airtight frame 36 to form the cavity 80, and the frame portion 22, the first fixed electrode 61, and the second fixed electrode 62 are hermetically sealed to the cavity 80. Is done.

Next, as shown in FIG. 12, the insulating film 42 and the bonded substrate 41 are ground from the side opposite to the supporting substrate 10 side, the insulating film 42 on the side opposite to the supporting substrate 10 side is removed, and the bonded substrate 41 is thinned. To do.

Next, as shown in FIG. 13, by removing the bonded substrate 41 and the insulating film 42 at locations corresponding to the first pad portion 31 and the third pad portion 33, two through holes 41a are formed. Further, in a cross section different from 13, two through holes 41 a are formed by removing the bonded substrate 41 and the insulating film 42 at locations corresponding to the fourth pad portion 34 and the fifth pad portion 35. That is, a total of 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 pad portion 31, the third pad portion 31, the fourth pad portion 34, and the fifth pad portion 35 are removed in each through hole 41a. Expose.

Next, as shown in FIG. 14, each through electrode 70 is formed by disposing a metal film in each through hole 41 a by sputtering or vapor deposition. Specifically, the first through electrode 71 is formed in the through hole 41 a corresponding to the first pad portion 31. A second through electrode 72 is formed in the through hole 41 a corresponding to the third pad portion 33. A third through electrode is formed in the through hole 41 a corresponding to the fourth pad portion 34. A fourth through electrode is formed in the through hole 41 a corresponding to the fifth pad portion 35. Thereafter, the metal film on the insulating film 43 is patterned to form the land portion 70a.

The inertial sensor 100 is manufactured through the processes described above. In addition, although the manufacturing method of the inertial sensor 100 which detects the acceleration applied to az-axis direction was demonstrated above, the sensing part which detects the acceleration applied to the direction along xy plane is provided in the same inertial sensor 100. FIG. 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, functions and effects of the inertial sensor 100 according to the present embodiment will be described.

In this inertial sensor 100, the movable part 20 constituting the sensing part is connected to the first pad part 31 and the first through electrode 71 via the relay wiring without being directly connected to the through electrode 70. For this reason, even when the first through electrode 71 expands or contracts due to temperature, it is possible to prevent the thermal stress from being directly transmitted to the second pad portion, and hence the movable portion 20. Therefore, noise caused by temperature superimposed on the sensor signal output from the sensing unit can be reduced.

The inertial sensor 100 has a first type slit 51 formed therein. Specifically, the supporting substrate 10 and thus the peripheral portion 30 of the second substrate 13 are partitioned by the first type slit 51 into the joint portion 30a and the base portion 30b. For this reason, even if the joint portion 30a is deformed due to the thermal stress of the through electrode 70, the first type slit 51 becomes a clearance with the base body portion 30b, so that the influence of the thermal stress on the movable portion 20 is affected. It can be suppressed more.

Furthermore, a second type slit 52 is formed in the inertial sensor 100. Specifically, the peripheral portion 30 of the support substrate 10 and thus the second substrate 13 is partitioned into an outer peripheral portion 30 c and an inner peripheral portion 30 d by the second type slit 52. For this reason, even when the penetration electrode 70 formed on the inner peripheral portion 30d side in the frame of the second type slit 52 expands or contracts due to the temperature, the second electrode 52 is formed between the inner peripheral portion 30d and the outer peripheral portion 30c. Since the two types of slits 52 serve as a clearance, the influence of thermal stress on the outer peripheral portion 30c can be further suppressed. For example, even in an inertial sensor in which a sensing unit for detecting acceleration applied in the x-axis direction and the y-axis direction is separately formed on the outer peripheral part 30c side, the influence of thermal stress on the sensing unit is affected. Can be suppressed.

(Second Embodiment)
In the first embodiment, the inertial sensor 100 in which the first pad portion 31 overlaps the peripheral portion 30 when viewed from the front in the z-axis direction has been described. However, the formation position of the first pad portion 31 does not necessarily overlap the peripheral portion 30.

The first pad portion 31 in the inertial sensor 110 in the second embodiment is formed so as to overlap the movable portion 20 as shown in FIGS. 15 and 16. Specifically, the first pad portion 31 is formed on the second surface 40 a of the cap substrate 40 so as not to contact the second substrate 13 while facing the second substrate 13. The first pad portion 31 and the second pad portion 32 are electrically connected by the relay wiring 63. The 1st penetration electrode 71 is connected to the 1st pad part 31 like a 1st embodiment. FIG. 15 is a cross-sectional view taken along line XV-XV shown in FIG.

Also in this inertial sensor 110, the first through electrode 71 and the second pad portion 32 formed on the movable portion 20 are not directly connected but are electrically connected via the relay wiring 63. For this reason, even when the first through electrode 71 expands or contracts due to temperature, it is possible to prevent the thermal stress from being directly transmitted to the second pad portion, and hence the movable portion 20.

(Third embodiment)
The through electrode 70 in the first embodiment and the second embodiment is formed on the same cap substrate 40 side as the substrate on which the fixed electrode 60 is provided. In contrast, the inertial sensor 130 in the third embodiment is formed on a support substrate 10 different from the substrate on which the fixed electrode 60 is provided, as shown in FIG.

The inertial sensor 130 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. 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. 17, 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. 17, the fifth through electrode 75 penetrates the insulating film 12 and reaches the first pad portion 31. That is, the fifth through electrode 75 is electrically connected to the movable portion 20 via the first pad portion 31, the relay wiring 63, and the second pad portion 32. The sixth through electrode 76 penetrates the insulating film 12 and reaches the third pad portion 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 this inertial sensor 130, the fifth through electrode 75 and the second pad portion 32 formed on the movable portion 20 are electrically connected via the relay wiring 63 without being directly connected. For this reason, even when the fifth through electrode 75 expands or contracts due to temperature, it is possible to prevent the thermal stress from being directly transmitted to the second pad portion, and hence the movable portion 20.

Further, like the inertial sensor 130 in the present embodiment, the through electrode 70 is formed on the substrate (support substrate 10) that is paired with the substrate (cap substrate 40) on which the fixed electrode 60 is formed. It is no longer necessary to form the through hole 41a. Thereby, since it is not necessary to reduce the thickness of the bonded substrate 41, the strength of the cap substrate 40 against the stress can be increased. That is, it is possible to suppress the occurrence of warpage with respect to the temperature. Therefore, compared with 1st Embodiment and 2nd Embodiment, the precision of the opposing distance between the fixed electrode 60 and the movable part 20 can be made high, and the precision of a sensor signal can be improved.

(Other embodiments)
In the above-described embodiment, the example in which the slit 50 of the support substrate 11 is provided and the slit 50 is used as a clearance against thermal strain has been described. However, the slit 50 is not necessarily provided. Further, only the first type slit 51 may be formed, or only the second type slit 52 may be formed. Moreover, if it functions as a clearance with respect to thermal distortion, it is not necessary to be a slit, and for example, a void-shaped buffer region may be provided in a portion corresponding to the formation position of the first type slit 51 or the second type slit 52.

In the above-described embodiment, an example in which aluminum is used for the pad portions 31 to 35, the hermetic frame 36, and the through electrode 70 has been described. However, gold or copper may be used.

(Fourth 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 the present embodiment is an inertial sensor that detects acceleration, for example. As shown in FIG. 18, the inertial sensor 2100 as a semiconductor device is configured by stacking a support substrate 210 and a cap substrate 240. FIG. 18 is a cross-sectional view taken along line XVIII-XVIII shown in FIG. FIG. 19 is a top view of the second substrate 213 in the support substrate 210.

The support substrate 210 is an SOI (Silicon on Insulator) substrate in which the second substrate 213 is disposed on the first substrate 211 via the insulating film 212, and the first surface 210 a is the insulating film of the second substrate 213. It is composed of a surface opposite to the 212 side. The first substrate 211 is made of a semiconductor such as silicon, the insulating film 212 is made of an oxide film or a nitride film, and the second substrate 213 is made of polysilicon or the like. In addition, an insulating film 212 a is formed on the first substrate 211 on the surface opposite to the surface on which the insulating film 212 is formed.

Then, as shown in FIGS. 18 and 19, the second substrate 213 is subjected to micromachining to form a groove portion 214, and the movable portion 220 and the peripheral portion 230 are partitioned by the groove portion 214.

Further, the first substrate 211 of the support substrate 210 has a portion facing the movable portion 220 in order to prevent the movable portion 220 and a frame portion 222 described later from coming into contact with the first substrate 211 and the insulating film 212. A recess 215 is formed. The recess 215 is formed by a method such as etching, and the insulating film 212 is formed over the surface of the recess 215.

The movable part 220 has a rectangular frame-shaped frame part 222 in which a planar rectangular opening part 221 is formed, and a torsion beam 223 formed so as to connect opposite sides of the opening part 221. The movable part 220 is supported by the first substrate 211 by connecting the torsion beam 223 to the anchor part 224 supported by the insulating film 212. This movable part 220 corresponds to a sensing part.

Here, the definition of the direction in the present embodiment will be described. As shown in FIGS. 18 and 19, the extending direction of the torsion beam 223 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 210 a of the support substrate 210. In other words, the z-axis direction is the thickness direction of the support substrate 210 and the cap substrate 240.

The torsion beam 223 is a member that becomes the rotation center axis of the movable portion 220 when an acceleration in the z-axis direction is applied. That is, the torsion beam 223 rotates with the extending direction as a rotation axis. The torsion beam 223 in this embodiment is formed so that the opening 221 is divided into two.

The frame portion 222 has an asymmetric shape with respect to the torsion beam 223 so that it can rotate about the torsion beam 223 when the acceleration in the z-axis direction is applied. The frame portion 222 in this embodiment is divided into a first portion 222a and a second portion 222b with the torsion beam 223 as a reference. The frame portion 222 has a length in the y-axis direction from the torsion beam 223 in the first part 222a to the end of the part farthest from the torsion beam 223, to the end of the part farthest from the torsion beam 223 in the second part 222b. Is shorter than the length in the y-axis direction. That is, in the frame part 222, the mass of the first part 222a is smaller than the mass of the second part 222b.

Further, the first bonded body 231, the second bonded body 232, the third bonded body 233, the fourth bonded body 234, and the fifth bonded body 235 are formed on the first surface 210 a of the support substrate 210, that is, the surface of the second substrate 213. And a sixth joined body 236 that functions as an airtight frame is formed. In the present embodiment, these joined bodies 231 to 236 are made of aluminum, for example, and are formed between the support substrate 210 and the cap substrate 240. In FIG. 19, the formation positions of these elements are indicated by broken lines.

Specifically, the first bonded body 231 is formed on the first surface 210 a that is the surface of the peripheral portion 230, and is connected to a first through electrode 271 described later via the peripheral portion 230. The second joined body 232 is formed on the anchor portion 224 and is electrically connected to the movable portion 220. The third bonded body 233 is formed on the first surface 210 a that is the surface of the peripheral portion 230, and is connected to a second through electrode 272 described later via the peripheral portion 230. In particular, the third bonded body 233 is electrically connected to the bonded substrate 241 via a cap substrate-side contact 242a provided on the insulating film 242. The fourth bonded body 234 is formed on the first surface 210 a that is the surface of the peripheral portion 230, and is connected to a third through electrode (not shown) via the peripheral portion 230. The fifth bonded body 235 is formed on the first surface 210 a that is the surface of the peripheral portion 230, and is connected to a fourth through electrode (not shown) via the peripheral portion 230. The third through electrode and the fourth through electrode have the same configuration as the first through electrode 271 and are formed side by side along the y-axis direction. That is, the potentials of the first bonded body 231, the third bonded body 233, the fourth bonded body 234, and the fifth bonded body 235 are the first through electrode 271, the second through electrode 272, 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 231 and the second joined body 232 are connected and electrically connected to each other by a relay wiring 263 described later. That is, the potential of the movable part 220 as a sensing part can be taken out from the first through electrode 71.

The sixth joined body 236 that functions as an airtight frame is formed in a frame shape so as to surround the movable portion 220 (groove portion 214). Since the sixth bonded body 236 is formed between the support substrate 210 and the cap substrate 240, the region surrounded by the sixth bonded body 236, the support substrate 210, and the cap substrate 240 is isolated from the outside. It is an airtight space. A cavity corresponds to this isolated space. Hereinafter, this isolation space is referred to as a cavity 280.

The 2nd board | substrate 213 in the support substrate 210 has the some slit 250 in the outer peripheral part 230, as shown in FIG.18 and FIG.19. The second substrate 213 in this embodiment has a first type slit 251 and a second type slit 252. Hereinafter, the first type slit 251 and the second type slit 252 may be collectively referred to as a slit 250.

The first type slit 251 is formed in a substantially annular shape so as to surround a contact portion of the second substrate 213 with the first bonded body 231, the third bonded body 233, the fourth bonded body 234, and the fifth bonded body 235. ing. As shown in FIG. 19, the first type slit 251 surrounding the contact portion with the first joined body 231 is annular, and hereinafter, the region surrounded by the slit is referred to as an island portion 230a. That is, the peripheral part 230 is divided into the island part 230a and the base part 230b excluding the island part 230a by the first type slit 251. In the present embodiment, as shown in FIG. 18, the first type slit 251 does not reach the first substrate 211 or the insulating film 212, but the present invention is not limited to this. The island part 230 a and the base part 230 b are concepts including the first substrate 211 and the insulating film 212.

Similarly to the first bonded body 231, a first type slit 251 is formed so as to surround a contact portion of the second substrate 213 with the third bonded body 233. The first type slit 251 corresponding to the third joined body 233 does not form a complete ring shape, but forms a C shape with a part missing. That is, the third bonded body 233 is electrically connected to the base body part 230b, and is connected to the bonded substrate 241 via the cap substrate side contact 242a penetrating the insulating film 242 described later. Similarly, the first type slit 251 is formed so as to surround the contact portion with the fourth bonded body 234 in the second substrate 213, and the first type slit 251 is surrounded so as to surround the contact portion with the fifth bonded body 235. Is formed. The first type slit 251 corresponding to the fourth joined body 234 and the fifth joined body 235 has an annular shape, and divides the island portion 230a and the base portion 230b.

As shown in FIG. 19, the second type slit 252 is formed in a frame shape so as to include the movable portion 220 and the contact portions of the peripheral portion 230 with the joined bodies 231, 233 to 235 inside. Yes. The second type slit 252 in the present embodiment is formed in a rectangular shape along the sixth joined body 236 in the frame in which the sixth joined body 236 is formed. The second type slit 252 partitions the second substrate 213 into an outer peripheral part 230c that is outside the frame of the second type slit 252 and an inner peripheral part 230d that is inside the frame. When viewed from the front in the z-axis direction, the outer peripheral portion 230c is a region of the support substrate 210 where the sixth joined body 236 is joined. On the other hand, the inner peripheral part 230d is an area including the movable part 220 and the above-described island part 230a.

As shown in FIG. 18, the cap substrate 240 includes a bonded substrate 241 and an insulating film 242 formed on one surface of the bonded substrate 241 that faces the support substrate 210. A cap substrate side contact 242 a that penetrates the insulating film 242 and reaches the bonded substrate 241 is formed in a portion of the insulating film 242 that contacts the third bonded body 233. The third bonded body 233 is formed so as to enter the inside of the cap substrate side contact 242 a and is in electrical contact with the bonded substrate 241. A second surface 240 a of the cap substrate 240 is formed on the surface of the insulating film 242 facing the support substrate 210. Note that the bonded substrate 241 is made of silicon or the like, and the insulating film 242 is made of an oxide film or a nitride film.

As shown in FIG. 19, a first fixed electrode 261 and a second fixed electrode 262 are formed on the second surface 240 a of the cap substrate 240. Hereinafter, the first fixed electrode 261 and the second fixed electrode 262 may be collectively referred to as a fixed electrode 260. The fixed electrode 260 is disposed opposite to the support substrate 210 and is formed so as not to contact the first surface 210a.

As shown in FIG. 19, the first fixed electrode 261 is formed so as to overlap the first portion 222a in the frame portion 222 when viewed from the front in the z-axis direction. In other words, the first fixed electrode 61 faces the first part 222a. The first fixed electrode 261 and the first portion 222a constitute an electrostatic capacity, and the electrostatic capacity changes as the movable part 220 is displaced with the torsion beam 223 as a rotation axis. The first fixed electrode 261 is electrically connected to the fifth joined body 235 through the first wiring 261a. That is, the potential of the first fixed electrode 261 can be detected through the fourth through electrode.

As shown in FIG. 19, the second fixed electrode 262 is formed so as to overlap the second portion 222b in the frame portion 222 when viewed from the front in the z-axis direction. In other words, the second fixed electrode 262 faces the second portion 222b. The second fixed electrode 262 and the second portion 222b constitute an electrostatic capacity, and the electrostatic capacity changes as the movable part 220 is displaced with the torsion beam 223 as a rotation axis. The second fixed electrode 262 is electrically connected to the fourth joined body 234 through the second wiring 262a. That is, the potential of the second fixed electrode 262 can be detected through the third through electrode. As described above, the potential of the first fixed electrode 261 is extracted by the fourth through electrode, and the potential of the second fixed electrode 262 is extracted by the third through electrode.

The fixed electrode 260, the first wiring 261a, and the second wiring 262a are made of aluminum, for example. In addition, the first fixed electrode 261 and the second fixed electrode 262 have the same planar shape, and form an equal capacitance between the first and second portions 222a and 222b when no acceleration is applied. is doing.

Furthermore, a relay wiring 263 is formed on the second surface 240a of the cap substrate 240 along the second surface 240a. The relay wiring 263 is made of, for example, aluminum, and electrically connects the first joined body 231 and the second joined body 232. With the relay wiring 263, the second joined body 232 and the first joined body 231, and thus the first through electrode 271 can be set to the same potential. Note that the relay wiring 263 in this embodiment extends in the x-axis direction so as to face the torsion beam 223. Here, the first wiring 261a, the second wiring 262a, and the relay wiring 263 described above are wirings formed in the cavity 280, and are so-called inner layer wirings. These inner layer wirings 261 a, 262 a, and 263 are formed on the insulating film 242 in the cap substrate 240, and have a structure that does not come into direct contact with the bonded substrate 241 mainly composed of silicon.

As described above, the movable unit 220 and the fixed electrode 260 constitute a sensing unit, and the first through electrode 271, the third through electrode, and the fourth through electrode can output a sensor signal corresponding to the acceleration. ing.

Next, a detailed configuration of the first through electrode 271, the second through electrode 272, the third through electrode, and the fourth through electrode will be described.

The first substrate 211 of the support substrate 210 is formed with a through electrode 270 that penetrates in the thickness direction (z-axis direction). The through electrode 270 in the present embodiment includes the first through electrode 271 and the second through electrode 272 shown in FIG. 18, 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 270.

The four through electrodes 270 are formed in the through hole 211a penetrating the insulating film 212a, the first substrate 211, and the insulating film 212 via the insulating film 211b. The insulating film 211b is formed as an integral insulating film by connecting the insulating film 212 and the insulating film 212a on the inner wall surface of the through hole 211a. The through electrode 270 is formed along the inner wall surface of the through hole 211a, and the land portion 270a is formed on the insulating film 212a.

As shown in FIG. 18, the first through electrode 271 passes through the insulating film 212 a, the first substrate 211, and the insulating film 212 and reaches the first bonded body 231 through the second substrate 213. That is, the first through electrode 271 is electrically connected to the movable portion 220 via the first joined body 231, the relay wiring 263, and the second joined body 232. The first through electrode 271 is a through electrode corresponding to a B-type through electrode. The first through electrode 271 may be formed immediately below the anchor portion 224 in the z-axis direction and connected to the movable portion 220 without using the relay wiring 263. However, as in the present embodiment, by passing through the relay wiring 263, it is possible to prevent the influence of the volume change caused by the heat of the first through electrode 271 from being directly transmitted to the movable part 220, and the aging of the sensing part. It is possible to suppress deterioration and improve measurement accuracy.

The second through electrode 272 passes through the insulating film 212a, the first substrate 211, and the insulating film 212 and reaches the peripheral portion 230 of the second substrate 213. The second through electrode 272 is also in electrical contact with the support substrate 211 via a support substrate side contact 212b provided on the insulating film 212a. Further, the peripheral portion 230 of the second substrate 213 is connected to the third bonded body 233, and the third bonded body 233 is in electrical contact with the bonded substrate 241 through the cap substrate side contact 242a. That is, the second through electrode 272 has the same potential as the support substrate 211, the peripheral portion 230 of the second substrate 213, the third bonded body 233, and the bonded substrate 241. For example, when the second through electrode 272 is set to the ground potential in the inertial sensor 2100, the bonded substrate 241, the peripheral portion 230, and the support substrate 211 can be set to the ground potential. The second through electrode 272 is a through electrode corresponding to a C-type through electrode.

The third through electrode and the fourth through electrode (not shown) penetrate the insulating film 212a, the first substrate 211, and the insulating film 212, and reach the fourth bonded body 234 and the fifth bonded body 235 through the second substrate 213, respectively. . That is, the third through electrode and the fourth through electrode are electrically connected to the second fixed electrode 262 and the first fixed electrode 261, respectively. The 3rd penetration electrode and the 4th penetration electrode are penetration electrodes equivalent to the A class penetration electrode.

The above is the schematic structure of the inertial sensor 2100 in the present embodiment. In such an inertial sensor 2100, when an acceleration in the z-axis direction is applied, the frame portion 222 rotates according to the acceleration with the torsion beam 223 as a rotation axis. And since the electrostatic capacitance between the 1st site | part 222a and the 1st fixed electrode 261 and the electrostatic capacitance between the 2nd site | part 222b and the 2nd fixed electrode 262 change according to an acceleration, this capacity | capacitance. The acceleration is detected based on the change. That is, inertial sensor 2100 is a Z-axis inertial sensor.

Next, a method for manufacturing inertial sensor 2100 will be described with reference to FIGS.

First, as shown in FIG. 20, a first substrate 211 constituting the support substrate 210 is prepared, a mask resist (not shown) is formed, and etching is performed to form a recess 215 in the first substrate 211. Thereafter, the insulating film 12 is formed on the first substrate 211 by a generally known method such as CVD or thermal oxidation.

Next, as shown in FIG. 21, the insulating film 212 and the second substrate 213 are joined to form a support substrate 210. The bonding of the insulating film 212 and the second substrate 213 is not particularly limited, but can be performed as follows, for example.

First, the bonding surface of the insulating film 212 and the bonding surface of the second substrate 213 are irradiated with N ₂ plasma, O ₂ plasma, or an Ar ion beam to activate the bonding surfaces of the insulating film 212 and the second substrate 213. Then, alignment is performed by an infrared microscope or the like using an appropriately formed alignment mark, and the insulating film 212 and the second substrate 213 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 212 and the second substrate 213 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. 22, a metal film (aluminum) is formed on the first surface 210a of the support substrate 210 by a CVD method or the like. Then, 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, a metal layer that becomes a part of the first bonded body 231 to the sixth bonded body 236 is selectively selected. To form. In FIG. 22, the fourth joined body 234 and the fifth joined body 235 are not shown, but are formed in this step. Before forming the metal bonded body, a step of forming a spacer for determining the height when the cap substrate 240 is bonded, which will be described later, may be inserted. Further, the bonded bodies 231 to 236 in the present embodiment are assumed to be aluminum, but gold or copper may be adopted.

Next, as shown in FIG. 23, grooves 214 and slits 250 are formed in the second substrate 213 by reactive ion etching or the like using a mask (not shown) such as a resist or an oxide film. Thus, the first substrate 210 in which the movable part 220 is formed and the peripheral part 230 is divided into the joint part 230a and the base part 230b or the outer peripheral part 230c and the inner peripheral part 230d is prepared.

In a process different from that shown in FIGS. 20 to 23, as shown in FIG. 24, a bonded substrate 241 is prepared, a mask resist (not shown) is formed, and etching or the like is performed to form a recess 216 in the bonded substrate 241. To do. Thereafter, an insulating film 242 is formed on the entire surface of the bonded substrate 241 by thermal oxidation or the like. Thereafter, the insulating film 242 is partially removed to form a contact hole to be the cap substrate side contact 242a.

Next, as shown in FIG. 25, a metal film (aluminum) is formed on a portion of the insulating film 242 that should face the support substrate 210. Then, the first fixed electrode 261 and the second fixed electrode 262 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. Further, in this step, a metal layer to be the remaining part of the first joined body 231 to the sixth joined body 236 is selectively formed. Further, in this step, the relay wiring 263, the first wiring 261a, and the second wiring 262a are formed. In forming the third bonded body 233, a metal film is formed so that the contact hole formed in the previous step is filled with the third bonded body 233 to become the cap substrate side contact 242a.

Note that the first fixed electrode 261 and the second fixed electrode 262 may be formed of polysilicon. In this case, after patterning the first fixed electrode 261 and the second fixed electrode 262 with polysilicon, the remaining portions of the first bonded body 231 to the sixth bonded body 236, the relay wiring 263, the first wiring 261a, The second wiring 262a may be formed using aluminum.

Next, as shown in FIG. 26, the support substrate 210 and the cap substrate 240 are joined. Specifically, alignment is performed by an infrared microscope or the like using an appropriately formed alignment mark, and a part of the first bonded body 231 to the sixth bonded body 236 formed on the support substrate 210 and the cap substrate 240 are aligned. The formed first bonded body 231 to a part of the sixth bonded body 236 are metal bonded at 300 to 500 ° C. As a result, the space between the support substrate 210 and the cap substrate 240 is sealed by the sixth joined body 236 to form the cavity 280, and the frame portion 222, the first fixed electrode 261, and the second fixed electrode 262 pass through the cavity 280. Hermetically sealed.

Next, as shown in FIG. 27, the bonded substrate 241 is ground from the side opposite to the support substrate 210 side to adjust the bonded substrate 241 to a desired thickness. Incidentally, the fixed electrode 260 is formed on the cap substrate 240 including the bonded substrate 241. For this reason, the thickness of the bonded substrate 241 is not affected by the stress or cooling / heating change assumed to be applied to the inertial sensor 2100 so that the facing distance between the movable part 220 and the fixed electrode 260 does not change unintentionally. The thickness should be set to ensure sufficient strength. In the conventional inertia sensor, in order to form the through electrode 270 on the cap substrate 240 side, it is necessary to reduce the thickness of the bonded substrate 241. On the other hand, in this embodiment, since the through electrode 270 is not formed on the cap substrate 240 side, it can be set to a thickness that can secure a sufficient strength against a stress and a change in cooling.

On the other hand, as shown in FIG. 27, the first substrate 211 is ground from the side opposite to the cap substrate 240 side to adjust the first substrate 211 to a desired thickness. The thickness of the first substrate 211 is determined in consideration of the ease of forming the through electrode 270.

After adjusting the thickness of the bonded substrate 241 and the first substrate 211 by grinding, a through hole 211c is formed from one surface of the first substrate 211 opposite to the cap substrate 240 as shown in FIG. The through hole 211c is formed by etching, for example. In the present embodiment, the through hole 211c is formed at a position corresponding to the first joined body 231, the third joined body 233, the fourth joined body 234, and the fifth joined body 235.

Next, as shown in FIG. 28, an insulating film 211b such as TEOS is formed on the wall surface of each through hole 211c. At this time, the insulating film 212a is configured by an insulating film formed on the first substrate 211 on the side opposite to the cap substrate 240 side. That is, the insulating film 212a and the insulating film 211b are formed in the same process. Hereinafter, the inner wall surface of the insulating film 211b is referred to as a through hole 211a.

Next, as shown in FIG. 29, the insulating film 211b formed at the bottom of each through hole 211a is partially removed, and the first joined body 231, the third joined body 233, the fourth inside the through hole 211a. The second substrate 213 that is in electrical contact with the bonded body 234 and the fifth bonded body 235 is exposed. At the same time, the insulating film 212a in the vicinity of the through hole 211a connected to the third bonded body 233 is etched to provide a contact hole to be the support substrate side contact 212b. As a result, the insulating film 212a is partially removed and the first substrate 211 is exposed.

Next, a metal film electrode is formed on the inner wall surface of each through hole 211a and in the vicinity of each through hole 211a. Specifically, the first through electrode 271 is formed in the through hole 211 a corresponding to the first joined body 231. A second through electrode 272 is formed in the through hole 211 a corresponding to the third joined body 233. In addition, a third through electrode is formed in the through hole 211 a corresponding to the fourth joined body 234. A fourth through electrode is formed in the through hole 211 a corresponding to the fifth joined body 235. Thereafter, the metal film on the insulating film 243 is patterned to form the land portion 270a. Thereby, the inertial sensor 2100 shown in FIG. 18 can be manufactured. In particular, the metal film constituting the land 270a in the second through electrode 272 is filled in the contact hole provided in the insulating film 212a to form the support substrate side contact 212b, and the second through electrode 272 and the support substrate 210 are formed. The first substrate 211 is electrically connected.

In addition, although the manufacturing method of the inertial sensor 2100 which detects the acceleration applied to az axis direction was demonstrated above, the sensing part which detects the acceleration applied to the direction along xy plane is provided in the same inertial sensor 2100. You may do it. In the above description, the manufacturing method of one acceleration sensor has been described. However, a wafer-like support substrate 210 and a cap substrate 240 may be prepared, and after dicing and cutting, the wafer may be divided into chips.

Next, the function and effect of the inertial sensor 2100 according to this embodiment will be described.

In the conventional inertial sensor, the through electrode 270 and the fixed electrode 260 are formed on the same substrate, for example, the cap substrate 240. In such a form, there is a demand for manufacturing the cap substrate 240 as thin as possible in order to form the through electrode 270, while the electrostatic capacitance between the fixed electrode 260 and the movable part 220 due to the deformation of the cap substrate 240. From the viewpoint of suppressing the change in capacitance, there has been a contradictory request to manufacture the cap substrate 240 as thick as possible.

In contrast, in the inertial sensor 2100 according to the present embodiment, the through electrode 270 is formed on the support substrate 210 formed as a substrate different from the cap substrate 241 on which the fixed electrode 260 is formed.

For this reason, the thickness of the bonded substrate 241 constituting the cap substrate 240 is set to a stress that is assumed to be applied to the inertial sensor 2100 so that the facing distance between the movable portion 220 and the fixed electrode 260 does not change unintentionally. It can be set to a thickness that can ensure sufficient strength against changes in cooling.

Further, from the viewpoint of the support substrate 210, the thickness of the first substrate 211 can be determined in consideration of the ease of forming the through electrode 270.

That is, the thickness of the support substrate 210 and the thickness of the cap substrate 240 can be arbitrarily set independently without considering contradictory requirements.

Therefore, a request to manufacture the support substrate 210 as thin as possible for the ease of forming the through electrode 270 and a request to manufacture the cap substrate 240 to a necessary and sufficient thickness for the purpose of suppressing a change in capacitance. Therefore, it is preferable to set the thickness of the cap substrate 240 to be thicker than that of the support substrate 210.

In addition, the inertial sensor 2100 according to the present embodiment includes the bonded substrate 241, the base body 230 b of the second substrate 213, the first substrate 242 a, and the support substrate side contact 212 b. The substrate 211 and the second through electrode 272 can be set to the same potential. Since the support substrate 210 and the cap substrate 240 are set to the same potential, a disturbance electric field in the cavity 280 can be hardly generated, and the accuracy of the sensor signal can be improved.

The cap substrate side contact 242a can be formed only by patterning the insulating film 242 in the manufacturing process of the inertial sensor 2100, and can be shared with another process of etching the insulating film 242. . That is, it can be realized only by changing the etching mask for patterning. Similarly, the support substrate side contact 212b can be formed only by patterning the insulating film 212a in the manufacturing process of the inertial sensor 2100, and only by changing the etching mask for patterning the insulating film 212a. Can be realized. That is, the bonded substrate 241, the base body 230 b in the second substrate 213, the first substrate 211, and the second through electrode 272 are set to the same potential without increasing the number of steps compared to the conventional manufacturing process. can do.

(Other embodiments)
In each of the above-described embodiments, examples in which aluminum is used for the joined bodies 231 to 236 and the through electrode 270 have been described. However, 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, after the through electrode 270 is formed, a moisture-resistant passivation film may be formed on the entire surface of the support substrate 210 opposite to the first surface 210a. For the passivation film, for example, PIQ (polyimide) or silicon nitride can be employed.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Claims (9)

1. A support substrate (10) having a first surface (10a);
   A cap substrate (40) having a second surface (40a) and bonded to the support substrate in a state where the second surface faces the first surface;
   A sensing unit (20, 30, 60) disposed in an airtight cavity (80) formed between the support substrate and the cap substrate and outputting a sensor signal corresponding to a physical quantity;
   A through electrode (70) formed so as to penetrate in the thickness direction of the support substrate or the cap substrate;
   A first pad portion (31) formed between the first surface and the second surface and electrically connected to a tip of the through electrode;
   Relay wiring (63),
   The sensing unit includes a second pad unit (32) that has the same potential as the sensing unit,
   When the support substrate is viewed from the thickness direction, the first pad portion and the second pad portion are arranged to be shifted from each other,
   The relay wiring is a semiconductor device that electrically connects the first pad portion and the second pad portion to each other.
2. The sensing unit includes a movable unit (20) that is displaced according to acceleration in a normal direction of the first surface;
   A peripheral portion (30) surrounding the movable portion;
   A fixed electrode (60) formed on the second surface of the cap portion and facing the movable portion;
   The semiconductor device according to claim 1, wherein when the support substrate is viewed from the thickness direction, the first pad portion is formed at a position overlapping the peripheral portion.
3. The support substrate has a joint part (30a) to which the first pad part is joined, and a base part (30b) excluding the joint part,
   The semiconductor device according to claim 1, wherein a clearance (51) is provided between the joint portion and the base body portion.
4. The cavity is a region surrounded by a frame-like airtight frame (36) formed between the first surface and the second surface and surrounding the sensing unit, the support substrate, and the cap substrate. Formed,
   When the support substrate is viewed from the thickness direction, the first pad portion is formed in a frame of the airtight frame,
   The support substrate has an outer peripheral part (30c) to which the airtight frame is joined, and an inner peripheral part (30d) to which the first pad part is joined, excluding the outer peripheral part,
   The semiconductor device according to any one of claims 1 to 3, wherein a clearance (52) is provided between the outer peripheral portion and the inner peripheral portion.
5. 5. The semiconductor device according to claim 1, wherein the relay wiring is formed along the second surface and electrically connects the first pad portion and the second pad portion.
6. A support substrate (210) having a first surface (210a);
   A cap substrate (240) having a second surface (240a) and bonded to the support substrate in a state where the second surface is opposed to the first surface;
   A fixed electrode (260) disposed between the support substrate and the cap substrate and fixed to the second surface in an airtight cavity (280);
   A sensing unit (220) that forms a capacitance by being formed opposite to the fixed electrode in the cavity and outputs a sensor signal according to the change in the capacitance;
   A semiconductor device comprising a through electrode (270) formed through the support substrate and electrically connecting the inside and outside of the cavity.
7. The through electrode is
   A type A through electrode for extracting the potential of the fixed electrode;
   A B-type through electrode (271) for extracting the potential of the sensing unit;
   A C-type through electrode (272) that is electrically connected to the support substrate and is also connected to the cap substrate to connect the support substrate and the cap substrate to each other. A semiconductor device according to 1.
8. The support substrate and the cap substrate are bonded to each other through a bonded body (231 to 236) containing a metal,
   The C-type through electrode is
   The support substrate is connected to the support substrate via a support substrate side contact (212b) formed on the support substrate, and reaches the joined body through the support substrate.
   The semiconductor device according to claim 7, wherein the joined body is connected to the cap substrate through a cap substrate-side contact (242 a) formed on the cap substrate in the cavity.
9. 9. The semiconductor device according to claim 6, wherein a thickness of the cap substrate is thicker than a thickness of the support substrate.

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