JP7688993B2 - Far-infrared sensor package and manufacturing method thereof, and far-infrared sensor and manufacturing method thereof - Google Patents

Description

This disclosure relates to a package for a far-infrared sensor and a manufacturing method thereof, as well as a far-infrared sensor and a manufacturing method thereof.

2. Description of the Related Art In recent years, as various electronic devices become smaller and more functional, there is a demand for them to be even smaller and thinner.
Furthermore, small electronic devices such as smartphones are also being made thinner, and there is a demand for even lower heights for the optical sensors and other devices mounted therein.

In response to the demand for thinner electronic devices, for example, one possible solution would be to make each of the components even thinner than before; however, making the components too thin could impair their mechanical strength and reduce the product quality of the electronic device. For this reason, in order to meet the demand for smaller and thinner electronic devices, it is effective to bring their dimensions closer to the dimensions of the electronic components; for example, it has been proposed to use wafer-level packaging technology.

However, when electronic devices such as optical sensors are made low-profile, light is incident on the optical sensor from a wide angle. For this reason, for example, in optical sensors such as illuminance sensors, a shift in the cutoff wavelength band of the infrared cut filter affects the output of the illuminance sensor, making it impossible to detect accurate illuminance.

In order to solve the above problems, an optical sensor device has been proposed that reduces the dependency on the angle of incidence of light by adding a layer made of an infrared absorbing composition (see, for example, Patent Document 1).

However, when a layer made of an infrared absorbing composition is added, as in the optical sensor device described in Patent Document 1, the number of components of the optical sensor device itself increases, necessitating a complex structure, which inevitably leads to increased costs.

International Publication No. 2016/181786

On the other hand, for example, there is a growing demand for a wider angle of incidence for far-infrared sensors. For this reason, studies are being conducted on the use of wafer-level packaging technology to reduce the height of far-infrared sensors, allowing light to be incident from a wider angle.

However, when the height of a far-infrared sensor is reduced using wafer-level packaging technology, for example if both wafers are flat, the transmission distance of the far-infrared rays into the components increases by the thickness of the components when light is incident from an oblique direction. This causes the intensity of the light incident on the optical sensor to attenuate, making it difficult to efficiently receive far-infrared rays.

The present disclosure has been made in consideration of the above problems, and aims to provide a package for a far-infrared sensor and a method for manufacturing the same, and a far-infrared sensor and a method for manufacturing the same, which can widen the angle of incidence of light while having a low-profile configuration and can efficiently receive far-infrared rays.

In order to solve the above problems, the far-infrared sensor of the present disclosure employs the following configuration.
[1] A far-infrared sensor package according to one aspect of the present disclosure includes a first substrate having, on one side thereof, a device region and an electrode arrangement region disposed outside the device region in a planar view; and a second substrate bonded to the one side of the first substrate so as to cover the device region, the second substrate having, on a lower surface thereof which is a bonding surface with the first substrate, a concave cavity portion for forming a sealed space between the device region and the second substrate, and a bonding portion disposed to surround the cavity portion in a planar view, and the second substrate is disposed so as to expose the electrode arrangement region of the first substrate in at least a part of the outer side of the bonding portion in a planar view, wherein the second substrate has inclined surfaces inclined along each other at outer edges of both the lower surface side and an upper surface side opposite to the lower surface side of the second substrate, the inclined surfaces being inclined from the upper surface side toward the lower surface side toward the outside of the second substrate in a planar view.

According to this aspect, the outer edges of both the lower surface side and the upper surface side opposite to the lower surface side of the second substrate are inclined so as to be inclined along each other so as to be directed toward the outside of the second substrate in a plan view as they move from the upper surface side to the lower surface side, and the second substrate is thinned at the outer edges of the upper surface side and the lower surface side, so that attenuation of far-infrared rays incident from an oblique direction can be suppressed. This makes it possible to widen the angle of incidence of light, and therefore to widen the detection angle of far-infrared rays. Therefore, even with a low-profile configuration, far-infrared rays can be efficiently received at a wide detection angle.
In addition, since the second substrate has the inclined surface, the opening on the upper surface side of the second substrate in the portion exposing the electrode arrangement region of the first substrate becomes large, and by wire bonding to the electrodes, it is possible to avoid interference with the capillary, which is a bonding tool, when manufacturing a module by COB (chip on board) for a printed circuit board or the like. This makes it possible to minimize the space on the second substrate for avoiding interference with the capillary. Therefore, the bonding quality by wire bonding is ensured, and the entire package can be made smaller, making it possible to reduce product costs.

[2] In the far-infrared sensor package of the above aspect [1], it is preferable that the first substrate and the second substrate are made of silicon substrates.

According to the far-infrared sensor package of this aspect, the first substrate and the second substrate are made of silicon substrates, so that the transmittance of far-infrared rays in the second substrate is increased, making it possible to efficiently receive far-infrared rays.
In addition, since the first and second substrates are made of silicon substrates that are easy to process, the accuracy of processing by dry etching or wet etching is improved. In addition, by using silicon substrates that are commonly available and have a (100) surface orientation as the first and second substrates, it is possible to reduce the availability and manufacturing costs.

[3] In the far-infrared sensor package of the above aspect [2], the inclined surface of the second substrate may be an inclined surface formed of the (111) surface of the silicon substrate, which is formed by anisotropically etching the (100) surface of the silicon substrate by wet etching, and the inclination angle of the inclined surface may be an angle derived from the crystal anisotropy of the silicon substrate.

According to the far-infrared sensor package of this embodiment, the inclined surface of the second substrate, specifically, the side surface that is the peripheral edge of the second substrate and the inner surface of the cavity portion, have an inclination of about 54.7°, which is a crystal angle resulting from the crystal anisotropy of the silicon substrate, consisting of the (111) surface of the silicon substrate. In this way, the inclined surface has a stable angle resulting from the crystal orientation of the silicon substrate, so that the thickness of the joint is more stable and uniform, and thus, even with the low-profile configuration as described above, the effect of efficiently receiving far-infrared rays at a wide detection angle can be obtained more stably.

[4] In the far-infrared sensor package according to any one of the above aspects [1] to [3], the first substrate and the second substrate may be rectangular in plan view, and the electrode arrangement area may be arranged along at least one side of the first substrate and the second substrate in plan view.

According to the far-infrared sensor package of this embodiment, the electrode arrangement area for providing the electrodes may be provided, for example, only on one side of the first substrate, or may also be provided on the other side opposite to this one side, so that it can be flexibly configured while considering, for example, the space required when COB-mounting the far-infrared sensor package to a printed circuit board or the like. Therefore, for example, when the electrode arrangement area is provided only on one side of the first substrate, it is possible to miniaturize the far-infrared sensor package and the printed circuit board on which the far-infrared sensor is mounted, and when an electrode arrangement area is provided on the other side as well, it is possible to accommodate more complex electrical connections.

[5] In the far-infrared sensor package according to any one of the above aspects [1] to [4], it is more preferable to adopt a configuration in which the peripheral edge of the joint in the second substrate is chamfered.

In this type of far-infrared sensor package, the peripheral edge of the joint is chamfered, which prevents chipping or chipping caused by the contact pressure of the dicing blade when the package is diced into individual chips, improving the sensor characteristics and the yield.

[6] A far-infrared sensor according to one aspect of the present disclosure includes a package for a far-infrared sensor according to any one of the aspects [1] to [5] above, a far-infrared detection element arranged in the device region of the first substrate, an electrode arranged in the electrode arrangement region of the first substrate, a first metal bonding film arranged in a position of the first substrate corresponding to the joint arranged in the second substrate, and a second metal bonding film arranged so as to cover an end face of the joint in the second substrate, and the first metal bonding film and the second metal bonding film are bonded to each other, thereby ensuring the sealed space above the far-infrared detection element, and is characterized in that the first substrate and the second substrate are bonded to each other.

According to this aspect, the outer edges of both the lower surface side and the upper surface side opposite to the lower surface side of the second substrate are inclined to each other so as to be inclined toward the outside of the second substrate in a plan view from the upper surface side toward the lower surface side, and by providing the far-infrared sensor package of the above aspect, as described above, it is possible to suppress attenuation of far-infrared rays that are incident from an oblique direction and head toward the far-infrared detection element. This makes it possible to widen the angle of incidence of light, thereby realizing a far-infrared sensor that can efficiently receive far-infrared rays at a wide detection angle while having a low-profile configuration.
In addition, by providing the package for a far-infrared sensor of the above aspect in which the second substrate has the above-mentioned inclined surface, as described above, the opening on the upper surface side of the second substrate in the portion exposing the electrode arrangement region of the first substrate becomes large, so that it is possible to avoid interference with the capillary when wire bonding the electrode. This makes it possible to minimize the space in the second substrate for avoiding interference with the capillary, so that the bonding quality by wire bonding is ensured and the package as a whole can be made smaller, thereby realizing a far-infrared sensor with reduced production costs.

[7] In the far-infrared sensor of the above aspect [6], it is more preferable that a pair of linear gas adsorption layers are provided on the surface of the second substrate exposed to the sealed space, except for a position facing the far-infrared detection element provided on the first substrate, and through a position facing the far-infrared detection element.

According to the far-infrared sensor of this aspect, when the direction of light incidence is fixed, the gas adsorption layer can be provided in a position that does not impede the incidence of light. Furthermore, by providing a gas adsorption layer of this configuration, the gas in the depressurized sealed space can be effectively adsorbed. This provides both the effect of increasing the incidence efficiency of far-infrared rays from the outside and the effect of increasing the degree of vacuum in the cavity, so that far-infrared rays can be received more efficiently at a wider detection angle, and the light receiving sensitivity of the far-infrared detection element is further improved.

[8] In the far-infrared sensor of the above aspect [7], it is further preferable that the gas adsorption layer is provided in a pair of lines at positions facing the far-infrared detection element.

According to the far-infrared sensor of this embodiment, by providing a gas adsorption layer arranged in a pair of multiple lines, light can be efficiently incident on the inside of the package even when the light is incident from the direction in which the gas adsorption layer is arranged. This has the effect of further increasing the incidence efficiency of far-infrared rays from the outside and the effect of increasing the degree of vacuum in the cavity, so that far-infrared rays can be received more efficiently at a wider detection angle and the light receiving sensitivity of the far-infrared detection element is further increased.

[9] A method for manufacturing a package for a far-infrared sensor according to one aspect of the present disclosure includes a step (1) of obtaining a first substrate by etching a surface of a substrate material to form a concave device region on one side, and a step (2) of obtaining a second substrate by etching a surface of the substrate material to form a through region in at least a part of the substrate material and a concave cavity on the lower side, which is a bonding surface with the first substrate, and further forming a bonding portion that is provided to surround the cavity portion in a plan view, and the step (2) is characterized in that the outer edges of both the lower side and the upper side of the second substrate, which is opposite to the lower side, are formed as inclined surfaces that are inclined to each other as they move from the upper side to the lower side so as to move toward the outside of the second substrate in a plan view.

According to this aspect, in step (2), the outer edges of both the lower surface side and the upper surface side opposite to the lower surface side of the second substrate are formed into inclined surfaces that are inclined along each other so as to move toward the outside of the second substrate in a plan view from the upper surface side toward the lower surface side, thereby thinning the second substrate at the outer edges of the upper surface side and the lower surface side, thereby manufacturing a far-infrared sensor package that can suppress attenuation of far-infrared rays incident from an oblique direction. This makes it possible to obtain a far-infrared sensor package that has a wide angle of incidence of light and a low profile configuration, yet can efficiently receive far-infrared rays at a wide detection angle.
Furthermore, in step (2), by forming the above-mentioned inclined surface on the second substrate, the opening on the upper surface side of the second substrate in the portion exposing the electrode arrangement region of the first substrate becomes large, so that it is possible to avoid interference with the capillary, which is a bonding tool, when wire bonding the electrodes. This makes it possible to minimize the space on the second substrate for avoiding interference with the capillary, ensure the bonding quality of the wire bonding, and reduce the size of the entire package, making it possible to manufacture the far-infrared sensor package at low cost.

[10] In the method for manufacturing a far-infrared sensor package according to the above aspect [9], it is preferable to use a substrate material made of a silicon substrate for the first substrate and the second substrate.

According to the manufacturing method of the far-infrared sensor package of this embodiment, the first substrate and the second substrate are obtained by using a silicon substrate having excellent transmittance of far-infrared rays as the substrate material, so that the transmittance of far-infrared rays in the second substrate is increased, and a package capable of efficiently receiving far-infrared rays is obtained.
Furthermore, since the silicon substrate is easy to process, the precision of processing by dry etching or wet etching is improved.
Furthermore, by using a silicon substrate, which is commonly available and has a (100) surface orientation, as the substrate material, it is possible to reduce the availability and manufacturing costs.

[11] In the manufacturing method of the far-infrared sensor package of the above aspect [10], the step (2) may be a method in which the inclined surface of the second substrate is formed as an inclined surface consisting of the (111) surface of the silicon substrate, which appears by anisotropically etching the (100) surface of the silicon substrate by wet etching, and the inclination angle of the inclined surface is an angle derived from the crystal anisotropy of the silicon substrate.

According to the manufacturing method of the far-infrared sensor package of this embodiment, in step (2), the inclined surface of the second substrate, i.e., the side surface of the peripheral edge of the second substrate 3 and the inner surface of the cavity portion, are formed into an inclined surface having a stable angle of about 54.7°, which is a crystal angle derived from the crystal anisotropy of the silicon substrate, made of the (111) plane of the silicon substrate, so that the thickness of the joint portion is more stable and uniform. This makes it possible to manufacture a far-infrared sensor package that has a low-profile configuration as described above, yet can more stably obtain the effect of efficiently receiving far-infrared rays at a wide detection angle.

[12] In the method for manufacturing a package for a far-infrared sensor according to any one of the above aspects [9] to [11], it is more preferable to adopt a method further including a step (10) of chamfering the peripheral portion of the joint in the second substrate by dry etching, either simultaneously with the step (2) or after the step (2).

According to the manufacturing method of the far-infrared sensor package of this embodiment, in step (10), the peripheral portion of the joint is chamfered by dry etching, so that the stress caused by the dicing blade can be dispersed when the chip is separated by dicing. This makes it possible to suppress the occurrence of chipping or chipping caused by the contact pressure of the dicing blade, improving the characteristics of the package and also improving the yield.

[13] A method for manufacturing a far-infrared sensor according to one aspect of the present disclosure is a method for manufacturing a far-infrared sensor having steps (1) and (2) included in the method for manufacturing a package for a far-infrared sensor according to any one of the aspects [9] to [12] above, and further including, after steps (1) and (2), a step (3) of forming a first metal bonding film on one surface side of the first substrate obtained in step (1) at a position corresponding to the bonding portion provided on the second substrate, a step (4) of arranging an electrode in an electrode arrangement region on the one surface side of the first substrate obtained in step (1), and a step (5) of arranging a far-infrared detection element in the device region of the first substrate obtained in step (1). 5), a step (6) of forming a second metal bonding film so as to cover the end face of the bonding portion in the second substrate obtained in the step (2), a step (8) of overlapping the first substrate and the second substrate so that the far-infrared detection element is disposed between the first substrate and the second substrate, and bonding the first metal bonding film and the second metal bonding film by applying pressure to each other to bond the first substrate and the second substrate while securing the sealing space above the far-infrared detection element, and a step (9) of cutting the first substrate along a dicing line to separate it into chip units.

According to this aspect, in steps (1) and (2), a far-infrared sensor package of the above aspect is manufactured in which the outer edges of both the lower surface side and the upper surface side opposite to the lower surface side of the second substrate are inclined toward the outside of the second substrate in a plan view as they move from the upper surface side to the lower surface side, and then, in steps (3) to (6), (8), and (9), a far-infrared sensor can be manufactured that can suppress attenuation of far-infrared rays that are incident from an oblique direction and move toward the far-infrared detection element, as described above. This makes it possible to manufacture a far-infrared sensor that has a low-profile configuration but can efficiently receive far-infrared rays at a wide detection angle.
Furthermore, by forming the inclined surface on the second substrate in step (2), as described above, the opening on the upper surface side of the second substrate in the portion exposing the electrode arrangement region of the first substrate becomes larger, so that it is possible to avoid interference with the capillary when mounting the far-infrared sensor on a printed circuit board or the like by wire bonding. This makes it possible to minimize the space on the second substrate for avoiding interference with the capillary, thereby ensuring the bonding quality by wire bonding and making it possible to miniaturize the entire package, and making it possible to manufacture at low cost a far-infrared sensor that can efficiently receive far-infrared rays at a wide detection angle.

[14] In the method for manufacturing a far-infrared sensor according to the aspect of [13] above, it is more preferable to further include a step (7) of applying a getter agent to cover at least a part of the surface of the second substrate obtained in the step (2) exposed to the sealed space secured by the cavity portion, excluding the position facing the far-infrared detection element provided on the first substrate, thereby forming a pair of linear gas adsorption layers through the position facing the far-infrared detection element.

According to the manufacturing method of the far-infrared sensor of this aspect, when the direction of the incoming light is fixed, in step (7), a pair of linear gas adsorption layers can be formed at positions that do not block the incoming light and that face the far-infrared detection element. In addition, a gas adsorption layer of this configuration can effectively adsorb gas in the reduced pressure sealed space. This provides both the effect of further increasing the efficiency of incoming far-infrared rays from the outside and the effect of increasing the degree of vacuum in the cavity, and allows the manufacture of a far-infrared sensor that can efficiently receive far-infrared rays at a wide detection angle and has improved light receiving sensitivity by the far-infrared detection element.

[15] In the method for manufacturing a far-infrared sensor according to the above aspect [14], it is further preferable that the step (7) is a method for forming the gas adsorption layer into a pair of lines at positions facing the far-infrared detection element.

According to the manufacturing method of the far-infrared sensor of this aspect, in step (7), the gas adsorption layer is formed in a pair of multiple linear shapes, so that the gas adsorption layer can be formed to allow light to efficiently enter the inside of the package even when the light is incident from the direction in which the gas adsorption layer is arranged. This has the effect of further increasing the incidence efficiency of far-infrared rays from the outside and the effect of increasing the degree of vacuum in the cavity, and it is possible to manufacture a far-infrared sensor that can receive far-infrared rays more efficiently at a wide detection angle and has further improved light receiving sensitivity by the far-infrared detection element.

According to the present disclosure, by being provided with the above configuration, it is possible to provide a package for a far-infrared sensor, a far-infrared sensor, and a manufacturing method thereof that can receive far-infrared rays efficiently while having a low-profile configuration and a wider angle of incidence of light.

1 is a plan view illustrating a schematic diagram of a far-infrared sensor package and a far-infrared sensor according to a first embodiment of the present disclosure. FIG. 2 is a diagram for illustrating a schematic diagram of the far-infrared sensor package and the far-infrared sensor according to the first embodiment of the present disclosure, and is a cross-sectional view taken along the line AA in FIG. FIG. 2 is a diagram for explaining a method for manufacturing a far-infrared sensor package and a far-infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing a procedure of step (2) for obtaining a second substrate. FIG. 2 is a diagram for explaining a method for manufacturing a far-infrared sensor package and a far-infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing a procedure of step (2) for obtaining a second substrate. FIG. 1 is a diagram for illustrating a schematic diagram of a method for manufacturing a far-infrared sensor according to a first embodiment of the present disclosure, showing a process for forming a second metal bonding film on an end face of a bonding portion in a second substrate (6) and a process for forming a gas adsorption layer so as to cover at least a portion of the surface exposed to a sealed space (7). FIG. 1 is a diagram for illustrating a schematic diagram of a method for manufacturing a far-infrared sensor package and a far-infrared sensor according to a first embodiment of the present disclosure, showing steps including a step (1) of obtaining a first substrate, a step (3) of forming a first metal bonding film on one surface of the first substrate at a position corresponding to a bonding portion of a second substrate, a step (4) of arranging a far-infrared detection element in a device region, and a step (5) of arranging an electrode in an electrode arrangement region on one surface of the first substrate. FIG. 1 is a diagram for illustrating a schematic diagram of a method for manufacturing a far-infrared sensor according to a first embodiment of the present disclosure, and is a process diagram showing a procedure of step (8) for bonding a first substrate and a second substrate to obtain a far-infrared sensor. FIG. 10 is a diagram for illustrating a schematic diagram of a method for manufacturing a far-infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing the procedure of step (9) of cutting the first substrate and the second substrate along dicing lines to separate them into chip units. FIG. 4 is a plan view illustrating a schematic diagram of a far-infrared sensor package and a far-infrared sensor according to a second embodiment of the present disclosure. 5 is a diagram for illustrating a schematic diagram of a far-infrared sensor package and a far-infrared sensor according to a second embodiment of the present disclosure, the diagram being a cross-sectional view taken along the line BB in FIG. 4. FIG. 11 is a plan view illustrating a schematic diagram of a far-infrared sensor package and a far-infrared sensor according to a third embodiment of the present disclosure. FIG. 11 is a plan view illustrating a schematic diagram of a far-infrared sensor package and a far-infrared sensor according to a fourth embodiment of the present disclosure.

Below, embodiments of the far-infrared sensor package and manufacturing method thereof, and the far-infrared sensor and manufacturing method thereof of the present disclosure are given, and their configurations are described with appropriate reference to Figures 1 to 7. Note that in the drawings used in the following description, characteristic parts may be enlarged for convenience in order to make the features of the far-infrared sensor package and far-infrared sensor of the present disclosure easier to understand, and the dimensional ratios of each component may differ from the actual ones. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present disclosure is not limited to them, and may be modified as appropriate within the scope of the present disclosure.

First Embodiment
Hereinafter, a far-infrared sensor package and a far-infrared sensor according to a first embodiment of the present disclosure, as well as a manufacturing method thereof, will be described in detail with reference to FIGS. 1, 2, and 3A to 3F.
Fig. 1 is a plan view for explaining the far-infrared sensor (far-infrared sensor package) 1 of the present embodiment, and Fig. 2 is a cross-sectional view taken along line A-A of the far-infrared sensor 1 shown in Fig. 1. Also, Figs. 3A to 3F are diagrams for explaining the method for manufacturing the far-infrared sensor (far-infrared sensor package) 1 of the present embodiment, showing the procedure of each step.

[Configuration of far-infrared sensor package and far-infrared sensor]
As shown in FIGS. 1 and 2, the far-infrared sensor package of this embodiment includes a first substrate 2 (base substrate) and a second substrate 3 (lid substrate).
The far-infrared sensor 1 of this embodiment is roughly configured to include, in addition to the first substrate 2 and the second substrate 3 constituting the above-mentioned far-infrared sensor package, a far-infrared detection element 4 arranged in a device region 22 formed on the upper surface (one surface) 2a of the first substrate 2.
That is, the far-infrared sensor 1 of this embodiment includes a far-infrared sensor package having a first substrate 2 and a second substrate 3, as will be described in detail later.

To explain in more detail, the far-infrared sensor 1 of this embodiment first includes the far-infrared sensor package of this embodiment having the above-mentioned first substrate 2 and second substrate 3.
Furthermore, the far-infrared sensor 1 of the present embodiment includes a far-infrared detection element 4 arranged in the device region 22 of the first substrate 2, electrodes 81, 82 arranged in the electrode arrangement regions 23a, 23b of the first substrate 2, a first metal bonding film 51 provided on the first substrate 2 at a position corresponding to the bonding portion 31 provided on the second substrate 3, and a second metal bonding film 52 provided so as to cover the end face 31a of the bonding portion 31 on the second substrate 3.
In addition, the far-infrared sensor 1 of the example shown in Figures 1 and 2 is provided with a gas adsorption layer 10 arranged on at least a part of the surface of the second substrate 3 exposed to the cavity C secured by the cavity portion 32, excluding a position facing the far-infrared detection element 4 provided on the first substrate 2.
In the far-infrared sensor 1 of this embodiment, the first metal bonding film 51 and the second metal bonding film 52 are bonded together by, for example, metal diffusion bonding, so that the first substrate 2 and the second substrate 3 are bonded together while maintaining a cavity C above the far-infrared detection element 4.
Each component of the far-infrared sensor 1 of this embodiment will be described in more detail below.

The first substrate 2 is a base substrate for the far-infrared sensor package and the far-infrared sensor 1, and is made of, for example, a silicon substrate. In the example shown in FIG. 1, the first substrate 2 is formed in a rectangular shape in a plan view. A device region 22 for arranging the far-infrared detection element 4, the details of which will be described later, is formed in a concave shape on the upper surface 2a of the first substrate 2, and in the illustrated example, the device region 22 is provided approximately in the center in a plan view. In addition, the upper surface 2a of the first substrate 2 is provided with electrode arrangement regions 23a and 23b that are arranged outside the device region 22 in a plan view.

The first substrate 2 can be obtained by dry etching a silicon substrate to form the device region 22. The device region 22 is, for example, a region formed in a rectangular shape in a plan view.
The planar shape of the first substrate 2 is not limited to the roughly rectangular shape shown in the figure, and other shapes may be adopted in accordance with the planar shape of the far-infrared sensor 1 .
In the example described in this embodiment, the upper surface 2 a and the lower surface 2 b of the first substrate 2 are configured to be approximately flat except for the device region 22 .
The first substrate 2 can also be obtained by forming the device region 22 by wet etching a silicon substrate.

The first substrate 2 also includes embedded wirings 71, 72 that are embedded within the first substrate 2 and electrically connected to the far-infrared detection element 4, and electrodes 81, 82 that are provided on the first substrate 2 outside the second substrate 3 arranged opposite the first substrate 2 in a planar view and are electrically connected to the embedded wirings 71, 72 via first contacts 91a, 92a.
Although detailed illustration is omitted in Figures 1 and 2, the second contacts 91b, 92b are electrically connected to the far-infrared detection element 4 via the first signal wiring portion 61 or the second signal wiring portion 62, so that the electrodes 81, 82 are configured to transmit the detection signal output from the far-infrared detection element 4 to the outside.

1 and 2, the far-infrared sensor 1 of this embodiment may further include an insulating layer around the device region 22 in the first substrate 2, around embedded wirings 71, 72 or around electrodes 81, 82, which will be described later, etc. Specifically, the insulating layer (not shown) may be provided on the upper surface 2a of the first substrate 2 in an area outside the far-infrared detection element 4 so as to surround the far-infrared detection element 4 in a plan view. This insulating layer is made of an insulating material, and is formed, for example, from a silicon oxide film such as silicon dioxide (SiO ₂ ), a silicon nitride film (SiN _x ), or the like.

The second substrate 3 is a lid substrate (cover) of the far-infrared sensor 1, and is made of, for example, a silicon substrate, similar to the first substrate 2. Moreover, the second substrate 3 in the illustrated example is formed in a rectangular shape in a plan view, similar to the first substrate 2.
More specifically, the second substrate 3 is joined to the upper surface 2a side of the first substrate 2 so as to cover the device region 22, and on the lower surface 3a side, which is the joining surface with the first substrate 2, has a concave cavity portion 32 for securing a cavity C between the device region 22 and the lower surface 3a, and a joining portion 31 that is roughly frame-shaped so as to surround the cavity portion 32 in a planar view.
In addition, the second substrate 3 has a through region 33 for exposing the electrode arrangement regions 23a, 23b of the first substrate 2 along at least a portion of the outer side of the joint 31 when viewed in a plan view, in the illustrated example, one side and the other side arranged opposite each other of the second substrate 3 which is rectangular in a plan view.
1 and 2, a pair of penetrating regions 33 are arranged at positions corresponding to the electrode arrangement region 23a and the electrode arrangement region 23b, via a cavity portion 32. In the illustrated example, the cavity portion 32 has a rectangular shape in a plan view.

The second substrate 3 has inclined surfaces that are inclined so that the outer edges of both the lower surface 3a side and the upper surface 3b side of the second substrate 3, i.e., the inner surface 32b of the cavity portion 32 shown in FIG. 2 and the side surface 31b which is the peripheral edge of the second substrate 3, are inclined to follow each other and move in the outward direction of the second substrate 3 in a plan view as they move from the upper surface 3b side to the lower surface 3a side.

In addition, in this embodiment, an example will be described in which the inner surface 32b of the cavity portion 32 in the second substrate 3 and the side surface 31b of the second substrate 3 are inclined surfaces made of the (111) surface of the silicon substrate, which are formed by anisotropic wet etching of the (100) surface of the silicon substrate.

In the example shown in FIG. 2, the inner surface 32b of the cavity portion 32 is inclined from the ceiling surface 32a toward the bottom surface 3a toward the outside of the second substrate in a plan view. As a result, the second substrate 3 is configured such that the side surface 31b and the inner surface 32b of the cavity portion 32 are roughly parallel to each other, and as a result, the thickness of the joint portion 31 is roughly the same as the thickness between the top surface 3b and the ceiling surface 32a, making it a uniform thickness.

The second substrate 3 is superimposed on the first substrate 2 so as to be approximately parallel to the first substrate 2 .
Like the first substrate 2, the planar shape of the second substrate 3 is not limited to an approximately rectangular shape as in the illustrated example, but can be a shape corresponding to the planar shape of the far-infrared sensor 1.
Further, the second substrate 3 is made of a silicon substrate that is transmissive to far-infrared rays, and is configured to allow far-infrared rays to be incident on the far-infrared detection element 4 .

The depth of the cavity portion 32 in the second substrate 3, i.e., the height of the joint portion 31, is not particularly limited as long as it is a height that can secure a space with a certain volume as the cavity C, and can be, for example, 30 to 100 μm.

The planar dimensions (area) of the end face 31a of the joint 31 are not particularly limited, but taking into consideration the need to ensure the bonding strength of the metal diffusion bonding between the first metal bonding film 51 and the second metal bonding film 52, which will be described in detail later, the end face 31a may be, for example, a roughly rectangular shape measuring 1.5 to 4.0 mm square.

In addition, in this embodiment, since the first substrate 2 and the second substrate 3 are made of silicon substrates, the transmittance of far-infrared rays in the second substrate 3 is increased, making it possible to efficiently receive far-infrared rays.
Furthermore, since the first substrate 2 and the second substrate 3 are made of a silicon substrate which is easy to process, the precision of processing by dry etching or wet etching is improved, resulting in further excellent element characteristics.
Furthermore, by adopting a silicon substrate, which is commonly available and in particular has a (100) surface orientation, as the first substrate 2 and the second substrate 3, it is possible to improve availability and reduce manufacturing costs.

In this embodiment, as described above, the inner side surface 32b of the cavity portion 32 in the second substrate 3 and the side surface 31b in the second substrate 3 are inclined surfaces formed by wet etching. Specifically, the silicon substrate is anisotropically etched by wet etching on the (100) surface of the silicon substrate using a commonly used etching solution such as hydrazine (N ₂ H ₄ ), potassium hydroxide (KOH), tetramethylammonium hydroxide (TMAH), etc. As a result, the (111) surface appears in the depth direction due to the crystal anisotropy of silicon, and an inclined surface due to this (111) surface is formed, without using a particularly complicated process or etching solution. As a result, the inner side surface 32b of the cavity portion 32 and the side surface 31b in the second substrate 3 are formed into an inclined surface at an angle derived from the crystal anisotropy of the silicon substrate, that is, about 54.7° at which the (111) surface appears.

As described above, the far-infrared detection element 4 is arranged to be housed in the concave device region 22 formed on the upper surface 2a side of the first substrate 2. Also, as described above, the far-infrared detection element 4 is arranged to transmit its detection signal to the outside from the electrodes 81, 82, and when placed in the device region 22 of the first substrate 2, its upper surface side is exposed to the cavity C which is a reduced pressure space.

The far-infrared detection element 4 may, for example, have a portion made of the constituent material of the first substrate 2, which is the base substrate, or may have a portion made of a material supplied from the outside, or may have a portion made of a mixture of the constituent material of the first substrate 2 and a material supplied from the outside.

As described above, the first metal bonding film 51 is provided on the upper surface 2 a of the first substrate 2 at a position corresponding to the bonding portion 31 of the second substrate 3 .
As described above, the second metal bonding film 52 is provided so as to cover the end face 31 a of the bonding portion 31 in the second substrate 3 .
In this embodiment, a first metal bonding film 51 provided on the first substrate 2 and a second metal bonding film 52 provided on the second substrate 3 are bonded, for example, by metal diffusion bonding to form a metal bonded body 50, and the first substrate 2 and the second substrate 3 are bonded together by this metal bonded body 50.

As shown in FIG. 1 , the first metal bonding film 51 and the second metal bonding film 52 are formed in a roughly frame-like shape that is rectangular in a plan view, and the metal bonded body 50 formed by metal diffusion bonding the first metal bonding film 51 and the second metal bonding film 52 is also formed in a roughly frame-like shape that is rectangular in a plan view.
In addition, a metal bonded body 50 consisting of a first metal bonding film 51 and a second metal bonding film 52 bonds the first substrate 2 and the second substrate 3 to each other, thereby forming a cavity C surrounded by the first substrate 2, the second substrate 3, and the metal bonded body 50.

More specifically, the metal bonded body 50 is composed of a first metal bonding film 51 consisting of a first base layer 51a disposed on the upper surface 2a of the first substrate 2 and a first bonding layer 51b laminated on the first base layer 51a, and a second metal bonding film 52 consisting of a second base layer 52a disposed on the tip of the bonding portion 31 of the second substrate 3 and a second bonding layer 52b laminated on the second base layer 52a.

The first base layer 51a and the second base layer 52a are bonded to the upper surface 2a of the first substrate 2 or the end surface 31a of the bonding portion 31 of the second substrate 3, respectively. By providing the above-mentioned base layers, the first bonding layer 51b is firmly bonded to the first substrate 2, and the second bonding layer 52b is firmly bonded to the bonding portion 31 of the second substrate 3.

The first underlayer 51 a and the second underlayer 52 a are formed as thin films on the upper surface 2 a of the first substrate 2 or on the tip of the bonding portion 31 of the second substrate 3 and made of a conductive metal material.
The material of the first underlayer 51a and the second underlayer 52a is not particularly limited, but is preferably a thin film made of, for example, tantalum (Ta) or titanium nitride (TiN).
The first underlayer 51a provided on the first substrate 2 side is connected to, for example, a ground (not shown). This ground can be provided on, for example, the lower surface 2b side of the first substrate 2, but may also be provided on the upper surface 2a side of the first substrate 2.

As described above, the first bonding layer 51b and the second bonding layer 52b are laminated on the first base layer 51a or the second base layer 52a, respectively.
The material of the first bonding layer 51b and the second bonding layer 52b is not particularly limited, but for example, when tantalum is used as the material of the first underlayer 51a and the second underlayer 52a, gold (Au) is used as the material of the first bonding layer 51b and the second bonding layer 52b. Also, when titanium nitride is used as the material of the first underlayer 51a and the second underlayer 52a, aluminum (Al) is used as the material of the first bonding layer 51b and the second bonding layer 52b.

In this embodiment, the first bonding layer 51b and the second bonding layer 52b are configured to be bonded to each other using the same material. That is, the first bonding layer 51b and the second bonding layer 52b are both configured to contain the same material, that is, either gold (Au) or aluminum (Al).

When the first metal bonding film 51 and the second metal bonding film 52 constituting the metal bonded body 50 are made of the above-mentioned materials, there is no particular limitation on the thickness of each layer. On the other hand, in consideration of electrical characteristics, strength during bonding, and the like, when the first base layer 51a and the second base layer 52a are made of tantalum and the first bonding layer 51b and the second bonding layer 52b are made of gold, the thickness is preferably in the range of {first bonding layer 51b (or second bonding layer 52b): 0.5 nm to 2 μm/first base layer 51a (or second base layer 52a): 0.05 to 0.2 μm}, for example.
Similarly, when the first base layer 51a and the second base layer 52a are made of titanium nitride and the first bonding layer 51b and the second bonding layer 52b are made of aluminum, it is preferable that the thicknesses are in the range of {first bonding layer 51b (or second bonding layer 52b): 1 to 3 μm/first base layer 51a (or second base layer 52a): 0.05 to 0.5 μm}, for example.

The sealing width of the cavity C by the metal bonded body 50, that is, the maximum width of the second metal bonding film 52 and the first metal bonding film 51 formed in a rectangular shape in plan view corresponding to the bonding portion 31, is not particularly limited. On the other hand, when considering increasing the bonding property of this portion and further increasing the sealing airtightness of the cavity C, the maximum width of the first metal bonding film 51 and the second metal bonding film 52 is preferably, for example, 0.10 to 0.30 mm when the first base layer 51a and the second base layer 52a are made of tantalum and the first bonding layer 51b and the second bonding layer 52b are made of gold. Also, when the first base layer 51a and the second base layer 52a are made of titanium nitride and the first bonding layer 51b and the second bonding layer 52b are made of aluminum, the maximum width of the second metal bonding film 52 and the first metal bonding film 51 is preferably, for example, 0.03 to 0.1 mm.

In this embodiment, the first metal bonding film 51 and the second metal bonding film 52 that constitute the metal bonded body 50 are configured from the layer structure described above, so that when the first substrate 2 and the second substrate 3 are stacked and pressurized, metal diffusion bonding is generated between the first base layer 51a and the first bonding layer 51b and the second base layer 52a and the second bonding layer 52b. This makes it possible to give the metal bonded body 50 a strong bonding structure and to firmly bond the first substrate 2 and the second substrate 3 while improving the sealing performance in the cavity C.

In this embodiment, the first and second substrates 2 and 3 are not limited to being bonded by metal diffusion bonding using the above-mentioned materials for the first and second metal bonding films 51 and 52. For example, the first and second metal bonding films 51 and 52 may be made of gold (Au) or tin (Sn) and bonded by Au-Sn eutectic bonding. In this case, for example, the first and second base layers 51a and 52a, and the first and second bonding layers 51b and 52b are each made of an Au-Sn eutectic alloy, and are heated and melted to a eutectic temperature to eutectic bond the first and second base layers 51a and 51b and the second and second bonding layers 52a and 52b. This allows the first and second substrates 2 and 3 to be bonded firmly and stably, and the cavity C can be sealed and airtight.

When each layer of the first metal bonding film 51 and the second metal bonding film 52 is made of gold or tin, the composition of each layer is not particularly limited, but for example, a layer containing 20 to 22% Au-Sn can be used.
In this case, the thickness of each of the first metal bonding film 51 and the second metal bonding film 52 is not particularly limited, but may be configured in a paste or ribbon shape having a thickness of, for example, 5 to 10 μm.
In addition, the sealing width when first metal bonding film 51 and second metal bonding film 52 are Au-Sn eutectic bonded together, i.e., the width of first metal bonding film 51 and second metal bonding film 52, is not particularly limited, but can be, for example, in the range of 0.1 to 0.5 mm.

Furthermore, the above-mentioned electrodes 81, 82, embedded wirings 71, 72, first contacts 91a, 92a, and second contacts 91b, 92b are provided on the upper surface 2a of the first substrate 2.

As described above, the embedded wiring 71, 72 electrically connects the far-infrared detection element 4 and the electrodes 81, 82. The embedded wiring 71, 72 is provided in a number corresponding to the number of electrodes 81, 82 and output terminals (not shown) of the far-infrared detection element 4, and only a part of the embedded wiring 71, 72 is shown in FIG. 2. The electrodes 81, 82 are electrically connected to the far-infrared detection element 4 via the first signal wiring portion 61 and the second signal wiring portion 62. The embedded wiring 71, 72 in the illustrated example is buried above the center in the thickness direction of the first substrate 2, and is arranged so as to extend below the electrodes 81, 82, and the first signal wiring portion 61 and the second signal wiring portion 62.

The material for the embedded wiring 71, 72 is not particularly limited as long as it is a wiring material or electrode material with excellent conductivity, and metal materials that have been used in this field traditionally can be used without any restrictions. Examples of such materials include conductive materials that are commonly used for embedded wiring, such as polysilicon wiring and aluminum (Al) wiring.

The electrodes 81 and 82 are electrically connected to the far-infrared detection element 4 via the embedded wiring 71 and 72 and the first contacts 91a and 92a, and output the detection signal from the far-infrared detection element 4 to the outside. The electrodes 81 and 82 are provided along the opposing edges of the electrode arrangement areas 23a and 23b secured on the upper surface 2a of the first substrate 2, and in the illustrated example, the electrodes 81 and 82 are provided at five locations facing each other. In addition, the electrodes 81 and 82 are provided on the outside of the second substrate 3, which is provided facing the first substrate 2, in a plan view. The electrodes 81 and 82 are provided so as to be electrically connected to various external devices that require the detection signal from the far-infrared detection element 4, for example.

As the material for the electrodes 81, 82, any metal material that has been conventionally used in this field can be used without any restrictions, and for example, a material in which an aluminum silicon alloy (AlSi) and titanium nitride (TiN) are sequentially laminated by a sputtering method can be used.
Furthermore, as will be described in detail later, when the electrodes 81, 82 are formed simultaneously in the same process as the first metal bonding film 51, the material of each of these electrodes may be the same as that of the first metal bonding film 51 described above.

The first contacts 91a, 92a electrically connect the embedded wirings 71, 72 to the electrodes 81, 82, and the second contacts 91b, 92b electrically connect the embedded wirings 71, 72 to the first signal wiring section 61 or the second signal wiring section 62. In the example shown in FIG. 2, the first contacts 91a, 92a are connected to one end of the embedded wirings 71, 72, and the second contacts 91b, 92b are connected to the other end of the embedded wirings 71, 72.

As a result of the above, the far-infrared detection element 4 is electrically connected to the electrodes 81 and 82 via the first signal wiring portion 61 and the second signal wiring portion 62, the second contacts 91b and 92b, the embedded wirings 71 and 72, and the first contacts 91a and 92a.

The materials constituting the first contacts 91a, 92a and the second contacts 91b, 92b are not particularly limited either, and any metal material conventionally used in this field can be used without any restrictions.
Furthermore, as in the case of the electrodes 81, 82, when the first contacts 91a, 92a and the second contacts 91b, 92b are formed simultaneously in the same process as the first metal bonding film 51, the material of each of these contacts may be the same as the material of the first metal bonding film 51 described above.

As described above, the gas adsorption layer 10 is provided on the surface of the second substrate 3 exposed to the cavity C provided by the cavity portion 32, excluding the portion facing the far-infrared detection element 4 provided on the first substrate 2. In the example shown in Figures 1 and 2, the gas adsorption layer 10 is provided in a planar surrounding shape so as to surround the portion of the second substrate 3 facing the far-infrared detection element 4 in a planar view.

The material of the gas adsorption layer 10 is not particularly limited as long as it is made of a getter agent capable of adsorbing gases such as hydrogen and oxygen, and for example, a getter agent containing at least titanium, zirconium, nickel, or the like can be used. By forming the gas adsorption layer 10 from the above getter agent, the gas adsorption effect of the gas adsorption layer 10 in the cavity C is improved, and the degree of vacuum is further increased.

The dimensions and shape of the gas adsorption layer 10 are not particularly limited, and can be designed as appropriate while taking into consideration the gas adsorption efficiency in the cavity C by the gas adsorption layer 10. In addition, it is preferable that the planar shape of the gas adsorption layer 10 be a rectangle that surrounds the entire periphery of the position corresponding to the far-infrared detection element 4 on the surface exposed to the cavity C secured by the cavity portion 32 in the second substrate 3, as in the example shown in FIG. 1, because this ensures a large placement area for the gas adsorption layer 10 and improves the airtightness quality in the cavity C.

In addition, in this embodiment, an example is shown in which the gas adsorption layer 10 is formed only at a position where it does not overlap with the far-infrared detection element 4. However, it is also possible to configure the far-infrared detection element 4 and the gas adsorption layer 10 to slightly overlap each other as long as the light reception by the far-infrared detection element 4 is not impaired.
On the other hand, from the viewpoint of maximizing the characteristics of the far-infrared sensor, it is more preferable that the far-infrared detection element 4 and the gas adsorption layer 10 do not overlap at all, as in the examples shown in Figures 1 and 2.

According to the far-infrared sensor 1 including the far-infrared sensor package of this embodiment, as described above, the outer edges of both the lower surface 3a side and the upper surface 3b side of the second substrate 3, i.e., the inner surface 32b of the cavity portion 32 and the side surface 31b which is the peripheral edge of the second substrate 3, are inclined surfaces that are inclined along each other so as to face the outer direction of the second substrate 3 in a plan view as they move from the upper surface 3b side to the lower surface 3a side. Since this portion of the second substrate 3 is thinned, it is possible to suppress attenuation of far-infrared rays incident from an oblique direction. This makes it possible to widen the angle of incidence of light, and therefore to widen the detection angle of far-infrared rays. Therefore, even with a low-profile configuration, far-infrared rays can be efficiently received at a wide detection angle.

In addition, by making the side surface 31b and the inner surface 32b of the cavity portion 32 of the second substrate 3 inclined surfaces as described above, the opening (see the through area 33 shown in Figures 2 and 3E, etc.) on the upper surface 3b side of the second substrate 3 in the portion exposing the electrode arrangement areas 23a, 23b of the first substrate 2 becomes large. As a result, by wire bonding the electrodes 81, 82, it is possible to avoid interference with the capillary, which is a bonding tool, when manufacturing a module by COB (chip on board) for a printed circuit board, etc., and the space on the second substrate 3 for avoiding interference with the capillary can be minimized. Therefore, the bonding quality by wire bonding is ensured, and the entire package constituting the far-infrared sensor can be made smaller, making it possible to reduce product costs.

In addition, according to the far-infrared sensor 1 including the far-infrared sensor package of this embodiment, the inner surface 32b of the cavity portion 32 in the second substrate 3 is further inclined, and therefore the joint portion 31 is uniformly thinned, so that attenuation of far-infrared rays incident from an oblique direction can be more effectively suppressed. This allows the light incidence range to be made wider, so that the effect of efficiently receiving far-infrared rays at a wide detection angle can be more stably obtained, even with the low-profile configuration as described above.

In addition, according to the far-infrared sensor 1 including the far-infrared sensor package of this embodiment, the inclination angle of the above-mentioned inclined surface of the second substrate 3, specifically, the side surface 31b of the second substrate 3 and the inner side surface 32b of the cavity portion 32, is about 54.7°, which is a crystal angle derived from the crystal anisotropy of the silicon substrate, which is made of the (111) plane of the silicon substrate. In this way, the inclined surface has a stable angle derived from the crystal orientation of the silicon substrate, so that the thickness of the joint portion 31 is more stable and uniform, and thus, even with the low-profile configuration as described above, the effect of efficiently receiving far-infrared rays at a wide detection angle can be obtained more stably.

Next, an example of a process related to various detections using the far-infrared sensor 1 of this embodiment will be described.
First, when infrared rays enter the second substrate 3 from the upper surface 3b side and pass through the second substrate 3, the far-infrared detection element 4 detects the far-infrared rays and outputs a detection signal. The detection signal output from the far-infrared detection element 4 passes through the first signal wiring portion 61 and the second signal wiring portion 62, the second contacts 91b, 92b, the embedded wirings 71, 72, and the first contacts 91a, 92a, and is output to the outside from the electrodes 81, 82. The detection signal output from the electrodes 81, 82 is transmitted to an external device (not shown) and a predetermined operation is performed.

[Far-infrared sensor package and method for manufacturing far-infrared sensor]
Next, a method for manufacturing the far-infrared sensor 1 including the far-infrared sensor package of this embodiment will be described in detail with reference to FIGS. 3A to 3F as appropriate (also see FIGS. 1 and 2 as appropriate for the configuration of the far-infrared sensor 1).

The method for manufacturing the far-infrared sensor 1 of the present embodiment is, for example, a method for manufacturing the far-infrared sensor 1 of the present embodiment as shown in FIG. 1 and FIG. 2, and first, the method includes at least the following steps (1) and (2) for manufacturing a package for the far-infrared sensor.
Step (1): The surface of a substrate material is etched to form a recessed device region 22 on the upper surface 2a side, thereby obtaining a first substrate 2.
Step (2): By etching the surface of the substrate material, a through region 33 is formed in at least a part of the silicon substrate, a concave cavity portion 32 is formed on the lower surface 3a side which is the bonding surface with the first substrate 2, and a bonding portion 31 is formed so as to surround the cavity portion 32 in a plan view, thereby obtaining the second substrate 3. At this time, the outer edges of both the lower surface 3a side and the upper surface 3b side of the second substrate 3, i.e., the inner side surface 32b of the cavity portion 32 and the side surface 31b which is the peripheral edge of the second substrate 3, are formed as inclined surfaces inclined to each other so as to be inclined toward the outside of the second substrate 3 in a plan view as they move from the upper surface 3b side to the lower surface 3a side of the second substrate 3.

The method for manufacturing the far-infrared sensor 1 of this embodiment further includes at least the following steps (3) to (9) after the above steps (1) and (2).
Step (3): A first metal bonding film 51 is formed on the upper surface 2 a of the first substrate 2 obtained in step (1) at a position corresponding to the bonding portion 31 provided on the second substrate 3 .
Step (4): Electrodes 81 and 82 are arranged in the electrode arrangement regions 23a and 23b on the upper surface 2a side of the first substrate 2 obtained in step (1).
Step (5): The far-infrared detection element 4 is disposed in the device region 22 of the first substrate 2 obtained in step (1).
Step (6): A second metal bonding film 52 is formed to cover the end face 31a of the bonding portion 31 of the second substrate 3 obtained in step (2).
Step (8): The first substrate 2 and the second substrate 3 are overlapped so that the far-infrared detection element 4 is disposed between the first substrate 2 and the second substrate 3, and the first metal bonding film 51 and the second metal bonding film 52 are pressed against each other to perform metal diffusion bonding, thereby bonding the first substrate 2 and the second substrate 3 while securing a cavity C above the far-infrared detection element 4.
Step (9): The first substrate 2 and the second substrate 3 are cut along the dicing lines L to separate them into individual chips.

In addition, in this embodiment, between the above steps (6) and (8), an example is described in which a step (7) is further provided in which a getter agent is applied to the surface of the second substrate 3 obtained in step (2) exposed to the cavity C secured by the cavity portion 32, so as to cover at least a portion of the surface, excluding the portion facing the far-infrared detection element 4 provided on the first substrate 2, to form a gas adsorption layer 10.

First, in step (1), the surface of a substrate material such as a silicon substrate is wet-etched or dry-etched to form a concave device region 22 for accommodating the far-infrared detection element 4, thereby producing the first substrate 2 (see the first substrate 2 in FIG. 3D).
Specifically, in step (1), first, a resist pattern (not shown) for forming a recessed device region 22 by wet etching is formed on the surface of a silicon substrate, which is the substrate material, by, for example, photolithography.
Next, the surface of the silicon substrate is dry-etched or wet-etched to form a recessed device region 22 .
Thereafter, the resist pattern is peeled off from the first substrate 2 .

In the step (1), when a resist pattern is formed by photolithography, for example, a spin coating method or the like can be used to form the resist pattern under conventionally known conditions.
In addition, in the step (1), the silicon substrate can be etched using dry etching, while a method using wet etching can also be adopted. Thus, the conditions for wet etching in the step (1) are not particularly limited, and for example, etching solutions such as hydrazine (N ₂ H ₄ ), potassium hydroxide (KOH), and tetramethylammonium hydroxide (TMAH), which have been generally used in the past for etching silicon substrates, can be used. In addition, the conditions such as the temperature of the etching solution and the etching time can be selected from conventionally known conditions without any restrictions.

Next, in the example described in this embodiment, in the above step (1), embedded wiring 71, 72 is formed in the first substrate 2 in positions other than the device region 22 (see the first substrate 2 in Figure 3D).

Specifically, first, an insulating film (oxide film) (not shown) is formed on the upper surface 2 a of the first substrate 2 .
Next, in the region where the insulating film (not shown) is formed, for example, a laminated structure of {TiN/AlSi/TiN} or an embedded wiring film made of polysilicon is formed by a method such as sputtering or vapor deposition (CVD).
Next, a resist pattern (not shown) for forming embedded wirings 71 and 72 is formed by photolithography.
Next, the buried wiring film is dry etched to form patterned buried wirings 71 and 72 .
Next, the resist pattern is peeled off from the first substrate 2 .

Next, an insulating film (not shown) (oxide film or nitride film) is formed on the buried wirings 71 and 72 by, for example, a vapor deposition method, thereby covering the buried wirings 71 and 72 .
Thereafter, if necessary, the insulating film (not shown) formed on the buried wirings 71 and 72 is planarized by, for example, a CMP method (Chemical Mechanical Polishing) or the like.

Next, in the example described in this embodiment, in the above step (1), holes are formed for providing the first contacts 91a, 92a and the second contacts 91b, 92b in a step (3) described later.
At this time, first, a resist pattern is formed by photolithography on the entire upper surface 2a of the first substrate 2 except for the positions where the above-mentioned holes are to be formed (positions corresponding to the first contacts 91a, 92a and the second contacts 91b, 92b).
Next, the upper surface 2 a of the first substrate 2 is dry etched to form holes for providing the first contacts 91 a , 92 a and the second contacts 91 b , 92 b at positions corresponding to both ends of the embedded wirings 71 , 72 .
Next, the resist pattern is peeled off from the first substrate 2 .

In this embodiment, the above step (1) is performed, and in step (2), the (100) surface of the silicon substrate is etched as described above to form a through region 33 in at least a portion of the silicon substrate, a concave cavity portion 32 is formed on the lower surface 3a, and a bonding portion 31 is formed in a roughly frame-like shape surrounding the cavity portion 32 in a plan view, thereby producing a second substrate 3 (see Figures 3A and 3B).

That is, in step (2), first, a substrate material, for example a silicon substrate, is prepared.
Next, a mask pattern made of an oxide film or the like (not shown) is formed on the surface of the silicon substrate by photolithography to form the cavity portion 32, the penetrating region 33, and the bonding portion 31 with the inclined side surface 31b by wet etching.

Next, one surface side (front surface: upper surface 3b side) of the silicon substrate is wet-etched to divide the silicon substrate into rectangular shapes while forming a through region 33, as shown in FIG. 3A. In this case, in the step (2) described in this embodiment, for example, the (100) surface of the silicon substrate is wet-etched to form the side surface of the silicon substrate as an inclined surface that exposes the (111) surface of the silicon substrate. As a result, the side surface 31b, which is the outer edge of the upper surface 3b side of the second substrate 3 made of the silicon substrate, is inclined toward the outside of the second substrate 3 in a plan view as it moves from the upper surface 3b side to the lower surface 3a side, forming a joint 31 having a side surface 31b made of an inclined surface of about 54.7°, which is an angle derived from the crystal anisotropy of the silicon substrate.

As described above, the inclined surface of the side surface 31b of the second substrate 3 is formed by the anisotropy of silicon when the silicon substrate is etched. More specifically, when a silicon substrate having a (100) surface is used as the second substrate 3 and this silicon substrate is etched, a gradient in the etching rate occurs due to the crystal anisotropy of silicon. This action results in a side surface 31b having an inclined surface shape as shown in the example shown, with the (111) surface appearing. The second substrate 3 obtained by this procedure has improved shape precision of the side surface 31b at the joint 31.

The dimensions and planar shape of the through region 33 formed in step (2) are not particularly limited, and may be any shape or dimensions as long as it exposes the electrodes 81 and 82 and allows easy connection to the outside.

Next, the other surface side of the silicon substrate (the lower surface 3a side which is to be bonded to the first substrate 2) is wet etched to form a concave cavity portion 32 surrounded by the bonding portion 31 as shown in FIG. 3B.
In step (2) of the example described in this embodiment, the outer edge of the lower surface 3a side of the second substrate 3 made of a silicon substrate, i.e., the inner side surface 32b of the cavity portion 32, is formed as an inclined surface that exposes the (111) surface of the silicon substrate by wet etching the (100) surface of the silicon substrate. As a result, the inner side surface 32b of the cavity portion 32 is formed as an inclined surface inclined to be aligned with the above-mentioned side surface 31b, i.e., an inclined surface of about 54.7°, which is an angle derived from the crystal anisotropy of the silicon substrate, so that it inclines toward the outside of the second substrate 3 in a plan view as it moves from the upper surface 3b side to the lower surface 3a side. In the far-infrared sensor 1 obtained by the manufacturing method of this embodiment, the region corresponding to the above-mentioned cavity portion 32 is secured as a cavity C, which is a sealed space.
Thereafter, the mask pattern made of an oxide film or the like (not shown) is peeled off from the second substrate 3 .

In step (2), similarly to step (1), when forming a resist pattern by photolithography, a mask pattern made of an oxide film or the like can be formed under conventionally known conditions, for example, by using a spin coat method or the like. Also, as the wet etching conditions in step (2), similarly to the conditions described in step (1), etching solutions such as N ₂ H ₄ , KOH, TMAH, etc., which have been conventionally used in etching silicon substrates, can be used, and conventionally known conditions such as the temperature of the etching solution and the etching time can be adopted without any restrictions. As a result, a (111) plane appears in the depth direction due to the crystal anisotropy of silicon, and an inclined surface due to this (111) plane can be formed, without using any particularly complicated process or etching solution.

In this embodiment, in step (2), for example, the bonding portion 31 and the through region 33 are formed by wet etching, and then the etching conditions are appropriately changed and the cavity portion 32 is formed by wet etching, so that a method of forming each in a separate process can be adopted. In this way, even when the bonding portion 31 and the through region 33, and the cavity portion 32 are formed in separate processes, the same wet etching device can be used, which improves production efficiency and also makes it possible to reduce manufacturing costs.

Next, in step (3), a first metal bonding film 51 made of a metal film is formed on the upper surface 2a side of the first substrate 2 obtained in step (1) at a position corresponding to the bonding portion 31 provided on the second substrate 3 (see FIG. 3D).
In the example described in this embodiment, by simultaneously performing steps (3) and (4), it is also possible to form the electrodes 81, 82 in the electrode arrangement regions 23a, 23b, together with the first metal bonding film 51, on the upper surface 2a of the first substrate 2. In this embodiment, in addition to the first metal bonding film 51 and the electrodes 81, 82, it is also possible to simultaneously form the first contacts 91a, 92a, the second contacts 91b, 92b, the first signal wiring portion 61, and the second signal wiring portion 62 in the simultaneously performed steps (3) and (4).

Specifically, first, a resist pattern made of an oxide film or the like (not shown) is formed on the upper surface 2a of the first substrate 2 on which the device region 22 is formed, by a photolithography method such as spray coating, in order to form the first metal bonding film 51. At this time, the resist pattern is formed on the entire surface of the upper surface 2a of the first substrate 2, except for the positions corresponding to the bonding portion 31 of the second substrate 3, the positions of the holes for forming the first contacts 91a, 92a, the first signal wiring portion 61 and the second signal wiring portion 62, and the second contacts 91b, 92b, and the positions for the planned formation of the electrodes 81, 82.

Next, a first metal bonding film 51 including a first base layer 51a and a first bonding layer 51b laminated on the upper surface 2a of the first substrate 2 is formed by, for example, sputtering, vapor deposition, plating, or other method.
In step (3), by appropriately selecting the materials and the stacking order, it is possible to form first metal bonding film 51 made of a thin film having the above-mentioned {Au/Ta} structure or {Al/TiN} structure.
In this case, when the second metal bonding film 52 formed on the second substrate 3 has an {Au/Ta} structure, the first metal bonding film 51 is also formed from the same material. In this case, the stacking order of the layers is adjusted so that the Au layer (first bonding layer 51b) of the first metal bonding film 51 and the Au layer (second bonding layer 52b) of the second metal bonding film 52 are bonded to each other.
Similarly, when second metal bonding film 52 has an {Al/TiN} structure, first metal bonding film 51 is also made of the same material. In this case, the stacking order of each layer is adjusted so that the Al layer (first bonding layer 51b) of first metal bonding film 51 and the Al layer (second bonding layer 52b) of second metal bonding film 52 are bonded to each other.
Thereafter, the resist pattern (not shown) is peeled off from the upper surface 2 a of the first substrate 2 .

In addition, in step (3) of the example described in this embodiment, as shown in FIG. 3D, a conductive material is laminated on the upper surface 2a side of the first substrate 2 by a method such as sputtering, vapor deposition, or plating, so that the first contacts 91a, 92a and the second contacts 91b, 92b are formed so as to be connected to both ends of the embedded wirings 71, 72, respectively.
Furthermore, in step (4), electrodes 81, 82 are formed so as to be connected to the first contacts 91a, 92a, respectively, and a first signal wiring portion 61 and a second signal wiring portion 62 are formed so as to be connected to the second contacts 91b, 92b, respectively.

At this time, the first contacts 91a, 92a and the second contacts 91b, 92b can be formed by, for example, using tungsten (W) by a method such as sputtering or vapor deposition so as to be embedded in the holes formed in the above step (2). The electrodes 81, 82 can be formed by sequentially stacking TiN and AlSi by a method such as sputtering at the intended positions for forming the electrodes 81, 82 (electrode arrangement areas 23a, 23b). Furthermore, the first signal wiring portion 61 and the second signal wiring portion 62 can also be formed by sequentially stacking TiN and AlSi by a method such as sputtering at the intended positions for forming the electrodes 81, 82.

On the other hand, for example, when the first contacts 91a, 92a and the second contacts 91b, 92b, the electrodes 81, 82, and the first signal wiring portion 61 and the second signal wiring portion 62 are formed simultaneously in the same process as the first metal bonding film 51, they can be formed using the same material as the above-mentioned first metal bonding film 51, for example, by a sputtering method, a vapor deposition method, a plating method, or the like. In this case, the first contacts 91a, 92a and the second contacts 91b, 92b, the electrodes 81, 82, and the first signal wiring portion 61 and the second signal wiring portion 62 have the same layered structure as the first metal bonding film 51, that is, an {Au/Ta} structure or an {Al/TiN} structure.

Next, in step (5), a far-infrared detection element 4 is placed in the device region 22 of the first substrate 2 obtained in step (1) (see FIG. 3D).

Next, in this embodiment, the above steps (3), (4), and (5) are carried out, and in parallel with these steps, in step (6), a process is carried out to form a second metal bonding film 52 so as to cover the end surface 31a of the bonding portion 31 formed on the second substrate 3, as described above (see FIG. 3C).

Specifically, first, a resist pattern made of an oxide film or the like (not shown) is formed on the lower surface 3a of the second substrate 3 obtained in step (2) by a photolithography method such as a spray coating method in order to form the second metal bonding film 52. At this time, the resist pattern is formed on the entire surface of the lower surface 3a of the second substrate 3 except for the end surface 31a of the bonding portion 31.

Next, a second metal bonding film 52 consisting of a second base layer 52a and a second bonding layer 52b laminated together is formed on the end surface 31a of the bonding portion 31 as shown in FIG. 3C by, for example, a sputtering method, a vapor deposition method, a plating method, or the like.
In this case, by appropriately selecting the materials and the stacking order, it is possible to form second metal bonding film 52 made of a thin film having the above-mentioned {Au/Ta} structure or {Al/TiN} structure.
Thereafter, the resist pattern (not shown) is peeled off from the lower surface 3 a of the second substrate 3 .

In the above steps (3) and (6), each layer of the first metal bonding film 51 and the second metal bonding film 52 can be made of gold (Au) or tin (Sn), for example, in order to bond the first metal bonding film 51 and the second metal bonding film 52 with Au-Sn eutectic bonding in the step (8) described below.

Next, in step (7), as described above, a getter agent is applied to cover at least a portion of the surface of the second substrate 3 exposed to the cavity C defined by the cavity portion 32, excluding the portion facing the far-infrared detection element 4 provided on the first substrate 2, to form a gas adsorption layer 10 (see FIG. 3C).

Specifically, first, a resist pattern (not shown) is formed on the lower surface 3a of the second substrate 3 by a photolithography method such as spray coating, or the lower surface 3a of the second substrate 3 is covered with a patterned metal mask (not shown). At this time, the above resist pattern is formed or the metal mask is arranged so as to cover the entire lower surface 3a of the second substrate 3 except for the position facing the far-infrared detection element 4.

Then, for example, a getter agent containing titanium, zirconium or nickel is applied to the lower surface 3a of the second substrate 3 by using a conventionally known dispenser or screen printing method, or a sputtering method, vapor deposition method, etc. At this time, as shown in Fig. 3C etc., the getter agent is applied so that the gas adsorption layer 10 surrounds the periphery of a position on the lower surface 3a of the second substrate 3 facing the far-infrared detection element 4.
Thereafter, the resist pattern or metal mask (not shown) is peeled off from the second substrate 3 .

Next, in step (8), as described above, the first substrate 2 and the second substrate 3 are overlapped so that the far-infrared detection element 4 is disposed between the first substrate 2 and the second substrate 3, and the first metal bonding film 51 and the second metal bonding film 52 are pressed against each other to form a metal diffusion bond, thereby bonding the first substrate 2 and the second substrate 3 while securing a cavity C above the far-infrared detection element 4 (see FIG. 3E).

Specifically, first, as shown in FIG. 3E, the first substrate 2 and the second substrate 3 are superimposed on each other so that the first metal bonding film 51 and the second metal bonding film 52 are butted against each other.
Next, the first substrate 2 and the second substrate 3 are pressed together to cause metal diffusion bonding to occur between the first metal bonding film 51 and the second metal bonding film 52, and these parts are bonded to form a metal bonded body 50.

The conditions for performing the above-mentioned diffusion bonding, i.e., the conditions for sealing the cavity C of the far-infrared sensor 1, are not particularly limited, but for example, when the first metal bonding film 51 on the first substrate 2 side and the second metal bonding film 52 on the second substrate 3 side have a layer structure of {Au (first bonding layer 51b or second bonding layer 52b)/Ta (first base layer 51a or second base layer 52a)}, it is preferable that the temperature condition is in the range of 300 to 350°C and the pressure is in the range of 450 to 900 kPa.

On the other hand, when the first metal bonding film 51 and the second metal bonding film 52 have a layer structure of {Al (first bonding layer 51b or second bonding layer 52b)/TiN (first base layer 51a or second base layer 52a)}, it is preferable that the temperature condition is in the range of 350 to 400°C and the pressure is in the range of 27 to 60 MPa, for example.

As described above, when the first substrate 2 and the second substrate 3 are joined, the sealing width (joining width) of the cavity C by the metal joint 50, i.e., the maximum width of the metal joint 50 formed corresponding to the joint portion 31, is not particularly limited. On the other hand, in consideration of improving the joining property of this portion and further increasing the sealing airtightness of the cavity C, the above-mentioned sealing width (maximum width) is preferably, for example, 0.10 to 0.30 mm when the first base layer 51a and the second base layer 52a are made of Ta and the first bonding layer 51b and the second bonding layer 52b are made of Au. Also, when the first base layer 51a and the second base layer 52a are made of TiN and the first bonding layer 51b and the second bonding layer 52b are made of Al, the width is preferably, for example, 0.03 to 0.1 mm.

In addition, in step (8), as described above, each layer of the first metal bonding film 51 and the second metal bonding film 52 may be made of gold (Au) or tin (Sn), and the metal bonded body 50 may be formed by Au-Sn eutectic bonding. In this case, it is preferable to set the temperature condition to a range of 300 to 400°C, the pressure to a range of 0 to 1 kPa, and the sealing width to 0.1 to 0.5 mm.

In this embodiment, in step (9), as shown in FIG. 3F, the first substrate 2 is cut along dicing lines L by blade dicing or the like to be separated into individual chips.
Through the above steps, the far-infrared sensor 1 including the far-infrared sensor package of this embodiment can be manufactured.
It should be noted that the order of the above steps may be changed, or the steps may be performed as the same steps, to the extent possible.

According to the method for manufacturing a package for a far-infrared sensor and the method for manufacturing a far-infrared sensor 1 of this embodiment, in steps (1) and (2), a package for a far-infrared sensor is manufactured in which the outer edges of both the lower surface 3a side and the upper surface 3b side of the second substrate 3, i.e., the inner surface 32b of the cavity portion 32 and the side surface 31b which is the peripheral edge of the second substrate 3, are inclined so as to be inclined along each other so as to be directed toward the outside of the second substrate 3 in a plan view as they move from the upper surface 3b side toward the lower surface 3a side, and then, in each of steps (3) to (6), (8), and (9) (which may further include step (7)), a far-infrared sensor 1 capable of suppressing attenuation of far-infrared rays that enter from an oblique direction and move toward the far-infrared detection element 4 can be manufactured. This makes it possible to manufacture a far-infrared sensor 1 that can efficiently receive far-infrared rays at a wide detection angle while having a low-profile configuration.

In addition, in step (2), by forming the lower surface 3a of the second substrate 3, i.e., the inner surface 32b of the cavity portion 32, as an inclined surface, the joint is uniformly thinned, making it possible to manufacture a far-infrared sensor 1 that can more effectively suppress attenuation of far-infrared rays incident from an oblique direction.

In addition, in step (2), by forming the side surface 31b of the second substrate 3 and the inner surface 32b of the cavity portion 32 into an inclined surface as described above, the opening on the upper surface 3b side of the penetration region 33 for exposing the electrodes 81, 82 provided on the first substrate 2 becomes larger as described above, so that, for example, when mounting the far-infrared sensor 1 on a printed circuit board or the like by wire bonding, interference with the capillary can be avoided. This makes it possible to minimize the space on the second substrate 3 for avoiding interference with the capillary, thereby ensuring the bonding quality by wire bonding and making it possible to miniaturize the entire package. Therefore, it becomes possible to manufacture the far-infrared sensor 1 that can efficiently receive far-infrared rays at a wide detection angle at low cost.

In addition, according to this embodiment, in step (2), the inner surface 32b of the cavity portion 32 of the second substrate 3 is further formed into an inclined surface, so that the joint portion 31 can be uniformly thinned, and the attenuation of far-infrared rays incident from an oblique direction can be more effectively suppressed. This makes it possible to manufacture a far-infrared sensor 1 that can efficiently and stably receive far-infrared rays at a wider detection angle.

Furthermore, according to this embodiment, in step (2), the inclination angle of the inclined surface consisting of the (111) plane of the silicon substrate in the second substrate 3, i.e., the side surface 31b of the second substrate 3 and the inner surface 32b of the cavity portion 32, are formed into an inclined surface with a stable angle of 54.7°, which is the crystal angle resulting from the crystal anisotropy of the silicon substrate, thereby making the thickness of the joint portion 31 more stable and uniform. This makes it possible to manufacture a far-infrared sensor 1 that has a low-profile configuration as described above, yet can more stably obtain the effect of efficiently receiving far-infrared rays at a wide detection angle.

Second Embodiment
Hereinafter, a far-infrared sensor package and a far-infrared sensor according to a second embodiment of the present disclosure, as well as a manufacturing method thereof, will be described in detail with reference to FIGS. 4 and 5 as appropriate.
FIG. 4 is a plan view for explaining the far-infrared sensor 110 of the present embodiment, and FIG. 5 is a cross-sectional view taken along the line BB of the far-infrared sensor 110 shown in FIG.
In the far-infrared sensor 110 of the second embodiment described below, the components common to the far-infrared sensor 1 of the first embodiment described above will be given the same reference numerals in the drawings, and detailed description thereof may be omitted.

As shown in Figures 4 and 5, the far-infrared sensor 110 of the second embodiment differs from the far-infrared sensor 1 of the first embodiment in that the through region 33 provided in the second substrate 3A and the electrode 82 provided in the electrode arrangement region 23b arranged on the upper surface 2a of the first substrate are provided only on one side of the first substrate 2 and the second substrate 3A in a planar view.
In the example shown in FIG. 5, the internal wiring, the first contact, and the second contact electrically connected to the first signal wiring portion 61 are omitted.

Furthermore, the far-infrared sensor 110 shown in Figures 4 and 5 differs from the far-infrared sensor 1 of the first embodiment described above in that the peripheral portion 31c of the joint 31A in the second substrate 3A is chamfered and the peripheral portion 31c is a vertical surface.

In the case where the first substrate 2 and the second substrate 3A are configured to have a rectangular shape in a plan view as in this embodiment, they may be arranged along at least one side. The far-infrared sensor of the present disclosure may also adopt a configuration in which the electrodes 81 and 82 are also provided on the other side opposite to the one side, as in the far-infrared sensors 1 and 100 of the first and second embodiments. This allows the positions and number of the electrodes 81 and 82 provided on the first substrate 2 and the through regions 33 provided on the second substrate 3A to be flexibly designed while considering, for example, the space required when COB-mounting the far-infrared sensor package on a printed circuit board or the like.
Therefore, when the electrode 82 (electrode arrangement region 23b) is provided only on one side of the first substrate 2 as in this embodiment, it is possible to miniaturize the far-infrared sensor package and the printed circuit board on which the far-infrared sensor 110 is mounted. On the other hand, when the electrode 81 (electrode arrangement region 23a) is provided on the other side as in the far-infrared sensors 1 and 100 of the first and second embodiments, it is possible to accommodate more complicated electrical connections.

Furthermore, according to the far-infrared sensor 110 of this embodiment, by adopting a configuration in which the peripheral portion 31c of the joint portion 31A is chamfered as described above, the stress caused by the dicing blade can be dispersed when the sensor is diced into individual chips. This makes it possible to suppress the occurrence of chipping or chipping caused by the contact pressure of the dicing blade, thereby improving the characteristics of the package and the sensor as well as the yield.

In addition, when manufacturing the far-infrared sensor 110 of this embodiment, in addition to the steps (1) to (9) described in the first embodiment, a method can be adopted that further includes a step (10) of chamfering the peripheral portion 31c of the bonding portion 31 in the second substrate 3 by dry etching, either simultaneously with the step (2) or after the step (2).
When step (10) is performed simultaneously with step (2), for example, a method can be adopted in which the side surface 31b of the second substrate 3A is first formed as an inclined surface by wet etching, and then the concave cavity portion 32 to be formed on the lower surface 3a of the second substrate 3A is formed by dry etching, and at the same time, the peripheral portion 31c of the bonding portion 31 is chamfered.
When step (10) is performed after step (2), a method can be adopted in which first, in step (2), a second substrate 3A having a cavity portion 32 and a bonding portion 31 is obtained by wet etching, and then, as step (10), a peripheral portion 31c of the bonding portion 31 is chamfered by further dry etching.

Third Embodiment
Hereinafter, the far-infrared sensor according to the third embodiment of the present disclosure will be described in detail with reference to FIG. 6 as appropriate.
FIG. 6 is a plan view for explaining a schematic configuration of the far-infrared sensor 120 according to the present embodiment.

As shown in FIG. 6, the far-infrared sensor 120 of this embodiment differs from the first and second far-infrared sensors 1 and 110 described above in that the gas adsorption layer 10A is arranged on the surface of the second substrate 3 exposed to the cavity C, except for the position facing the far-infrared detection element 4 provided on the first substrate 2, and is provided in a pair of lines through the position facing the far-infrared detection element 4. In the example shown in FIG. 6, the gas adsorption layer 10A in the planar line-of-sight shape is provided in one place each through the position facing the far-infrared detection element 4.

According to the far-infrared sensor 120 of this embodiment, when the direction of light incidence is fixed, the gas adsorption layer 10A can be arranged in a pair of lines at a position that does not obstruct the incidence of light. Furthermore, by providing the gas adsorption layer 10A arranged in such a pair of lines, the gas in the reduced pressure sealed space can be effectively adsorbed. This provides both the effect of increasing the incidence efficiency of far-infrared rays from the outside and the effect of increasing the degree of vacuum in the cavity C, so that far-infrared rays can be efficiently received at a wide detection angle, and the light receiving sensitivity of the far-infrared detection element 4 is further improved.

When manufacturing the far-infrared sensor 120 of this embodiment, in step (7) described in the first embodiment, the gas adsorption layer 10A is formed into a pair of lines through the position facing the far-infrared detection element 4 by applying a getter agent to cover at least a portion of the surface of the second substrate 3 exposed to the cavity C, excluding the position facing the far-infrared detection element 4 provided on the first substrate 2.

Fourth Embodiment
Hereinafter, the far-infrared sensor according to the fourth embodiment of the present disclosure will be described in detail with reference to FIG. 7 as appropriate.
FIG. 7 is a plan view illustrating a schematic configuration of the far-infrared sensor 130 according to the present embodiment.

As shown in FIG. 7, the far-infrared sensor 130 of this embodiment differs from the far-infrared sensor 120 of the third embodiment described above in that the gas adsorption layer 10B is provided in pairs in a line shape, with the gas adsorption layer 10B facing the far-infrared detection element 4. In the example shown in FIG. 7, the gas adsorption layer 10B in a planar line shape is provided in parallel in three places, with the gas adsorption layer 10B facing the far-infrared detection element 4.

According to the far-infrared sensor 130 of this embodiment, by providing a gas adsorption layer 10B arranged in a pair of multiple lines, light can be efficiently incident on the inside of the package even when the light is incident from the direction in which the gas adsorption layer 10B is arranged. This has the effect of further increasing the incidence efficiency of far-infrared rays from the outside and the effect of increasing the degree of vacuum in the cavity C, so that far-infrared rays can be received more efficiently at a wider detection angle and the light receiving sensitivity of the far-infrared detection element 4 is further increased.

When manufacturing the far-infrared sensor 130 of this embodiment, in step (7) described in the first embodiment, the gas adsorption layer 10B may be formed in a pair of lines through a position facing the far-infrared detection element 4 on the surface of the second substrate 3 exposed to the cavity C.

The position and shape of the gas adsorption layer are not limited to those shown in FIG. 7 (and FIG. 6), and detailed illustration is omitted. For example, the gas adsorption layer may be provided in a dotted shape on the surface of the second substrate exposed to the cavity, except for the position facing the far-infrared detection element. When the gas adsorption layer is formed in a dotted shape, a large effective adsorption area can be secured without impeding the incidence of far-infrared rays from the outside, and as described above, the gas in cavity C can be effectively adsorbed, and the degree of vacuum in cavity C can be increased.

As described above, the far-infrared sensor of the present disclosure has a low-profile configuration, yet can widen the range of light incidence and efficiently receive far-infrared rays. Therefore, the package of the present disclosure is highly suitable for use in electronic devices that require various types of highly reliable detection accuracy, such as mobile terminals, smartphones, sensor network devices, and Internet of Things (IoT) technology.

1, 100, 110, 120, 130... Far-infrared sensor (far-infrared sensor package)
2...First substrate 2a...Top surface 2b...Bottom surface 22...Device area 23a, 23b...Electrode arrangement area 3, 3A...Second substrate 3a...Bottom surface 3b...Top surface 31...Joint part 31a...End surface 31b...Side surface 31c...Peripheral part 32, 32A...Cavity part 32a...Ceiling surface 32b, 32c...Inner surface 33... Penetrating region 4... Far-infrared detection element 50... Metal bonding body 51... First metal bonding film 51a... First base layer 51b... First bonding layer 52... Second metal bonding film 52a... Second base layer 52b... Second bonding layer 61... First signal wiring section 62... Second signal wiring section 71, 72... Embedded wiring 81, 82... Electrode 91a, 92a...first contact 91b, 92b... second contact 10... gas adsorption layer

Claims (12)

a first substrate having, on one surface thereof, a device region and an electrode arrangement region arranged outside the device region in a plan view;
a second substrate bonded to the one surface side of the first substrate so as to cover the device region, the second substrate having a concave cavity portion for forming a sealed space between the device region and the lower surface side which is a bonding surface with the first substrate, and a bonding portion provided so as to surround the cavity portion in a plan view, and the second substrate provided so as to expose the electrode arrangement region of the first substrate in at least a part of the outer side of the bonding portion in a plan view;
Equipped with
The second substrate is characterized in that the outer edges of both the bottom surface side and the top surface side opposite the bottom surface side of the second substrate have inclined surfaces that are inclined along each other and toward the outside of the second substrate in a planar view as they move from the top surface side to the bottom surface side. The far-infrared sensor package according to claim 1, characterized in that the first substrate and the second substrate are made of silicon substrates. The package for a far-infrared sensor according to claim 2, characterized in that the inclined surface of the second substrate is an inclined surface consisting of the (111) surface of the silicon substrate, which is formed by anisotropically etching the (100) surface of the silicon substrate using wet etching, and the inclination angle of the inclined surface is an angle derived from the crystal anisotropy of the silicon substrate. The first substrate and the second substrate are rectangular in plan view,
The far-infrared sensor package according to any one of claims 1 to 3, characterized in that the electrode arrangement area is arranged along at least one side of the first substrate and the second substrate in a planar view. The far-infrared sensor package according to any one of claims 1 to 4, characterized in that the peripheral edge of the joint in the second substrate is chamfered. A package for a far-infrared sensor according to any one of claims 1 to 5;
a far-infrared detection element disposed in the device region of the first substrate;
an electrode disposed in the electrode arrangement region of the first substrate;
a first metal bonding film provided on the first substrate at a position corresponding to the bonding portion provided on the second substrate;
a second metal bonding film provided so as to cover an end surface of the bonding portion of the second substrate;
Equipped with
A far-infrared sensor characterized in that the first metal bonding film and the second metal bonding film are bonded to each other, thereby bonding the first substrate and the second substrate while securing the sealed space above the far-infrared detection element. The far-infrared sensor according to claim 6, characterized in that a pair of linear gas adsorption layers are provided on the surface of the second substrate exposed to the sealed space, except for a position facing the far-infrared detection element provided on the first substrate, and through the position facing the far-infrared detection element. The far-infrared sensor according to claim 7, characterized in that the gas adsorption layer is provided in pairs in the form of multiple lines, with a position facing the far-infrared detection element. (1) obtaining a first substrate by etching a surface of a substrate material to form a recessed device region on one side;
and (2) forming a through region in at least a part of the substrate material by etching a surface of the substrate material, forming a concave cavity portion on a lower surface side which is a bonding surface with the first substrate, and further forming a bonding portion provided so as to surround the cavity portion in a plan view to obtain a second substrate.
The method for manufacturing a package for a far-infrared sensor is characterized in that the process (2) is characterized in that the outer edges of both the bottom surface side and the top surface side opposite the bottom surface side of the second substrate are formed as inclined surfaces that are inclined along each other and toward the outside of the second substrate in a planar view as they move from the top surface side to the bottom surface side. The method for manufacturing a package for a far-infrared sensor according to claim 9, characterized in that a substrate material made of a silicon substrate is used for the first substrate and the second substrate. The method for manufacturing a package for a far-infrared sensor according to claim 10, characterized in that in step (2), the inclined surface in the second substrate is formed as an inclined surface made of the (111) surface of the silicon substrate, which appears by anisotropically etching the (100) surface of the silicon substrate by wet etching, and the inclination angle of the inclined surface is an angle derived from the crystal anisotropy of the silicon substrate. The method for manufacturing a package for a far-infrared sensor according to any one of claims 9 to 11 further comprises a step (10) of chamfering the peripheral portion of the joint in the second substrate by dry etching, either simultaneously with or after the step (2).

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