JP2023133922A - Infrared sensor and infrared sensor manufacturing method - Google Patents

Abstract

To provide an infrared sensor which has simple constitution and is manufactured by a simple manufacturing process and in which temperature rise of a cold junction can be suppressed by avoiding infrared incidence the cold junction and which therefore enables excellent sensor sensitivity and sensor quality to be obtained, and is low cost and has high yield and productivity.SOLUTION: An infrared sensor includes: a first substrate 2 having a device area 22; a second substrate 3 bonded to an upper surface side 2a of the first substrate 2 in such a way as to cover the device area 22; thermocouple 41, located in device area 22 of first substrate 2 and disposed on a membrane thin film 4a; and a thermopile-type infrared detection element 4 which is a part of the thermocouple 41 and has cold junction 42 disposed outside a device area 22 and a hot junction 43 located on the membrane thin film 4a. A second metal junction film 52 provided on a bottom side 3A of the second substrate 3 has an infrared block part 52A, spaced from the cold junction 42 on the first substrate 2 while extending to oppose at least a part of the cold junction 42.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to an infrared sensor and a method of manufacturing an infrared sensor.

In recent years, various electronic devices have been required to be further downsized and thinner as these electronic devices become smaller and more sophisticated. Along with this, for example, small electronic devices such as smartphones are becoming further smaller and thinner, and optical sensors and the like mounted thereon are also required to be further downsized.

In response to the demand for miniaturization of electronic devices, for example, it is effective to make their dimensions closer to those of electronic components, and for example, it has been proposed to use wafer level packaging technology.
In particular, as thermopile-type infrared sensors are actively being considered for installation in mobile devices and the like, demands for miniaturization are increasing.

On the other hand, when a thermopile-type infrared sensor is installed in a mobile device, etc., the overall device size is very small, so the distance between the cold junction and hot junction provided in the thermopile-type infrared detection element becomes small. , a decrease in sensor sensitivity occurs. As a measure to prevent such a decrease in sensitivity of a thermopile type infrared sensor, a method has conventionally been used in which an infrared absorbing film is disposed to cover the hot junction from above to improve the sensor sensitivity. However, if the above-mentioned infrared absorbing film is formed on the cold junction, the temperature will also rise at the cold junction when infrared rays are incident, so the temperature difference between the hot junction and the cold junction will become smaller, making it less efficient. It becomes difficult to generate an electromotive force. Therefore, there is a problem in that the output signal from the thermopile type infrared sensor decreases, that is, the sensor sensitivity decreases.

In order to solve the above problems, for example, by arranging a member that restricts the formation range of the infrared absorbing film, it is possible to prevent the infrared absorbing film from being formed on the cold junction and increase the sensor output. It has been proposed to improve the sensitivity (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2015-132470

However, in order to suppress the temperature rise of the cold junction when infrared rays are incident on a thermopile type infrared sensor, a member that restricts the formation range of the infrared absorbing film or a material that blocks infrared rays incident from the outside is used as described above. If such members are provided, the manufacturing process becomes complicated. Therefore, the yield of infrared sensors may decrease due to a decrease in sensor quality, difficulty in manufacturing management, and the like.

In particular, thermopile-type infrared sensors generally have a membrane structure in which a hot junction consisting of a part of a thermocouple is placed on a membrane thin film in order to efficiently absorb heat at the hot junction. We are hiring. For this reason, adding a member that restricts the formation range of the infrared absorbing film or a member that blocks infrared rays incident from the outside, as described above, will cause unexpected stress to be applied to the thermocouple, resulting in damage to the infrared sensor. There is a problem that the quality may be deteriorated due to the risk of the product being damaged.

Furthermore, since the structure involves a complicated process, there is a risk that manufacturing control and yield will be lowered, so there is a problem that it is not possible to meet the market's demand for cost reduction.

The present disclosure has been made in view of the above problems, and the temperature of the cold junction is increased by avoiding infrared rays from entering the cold junction using a simple configuration and manufacturing process without adding any new components. It is an object of the present invention to provide an infrared sensor and a method for manufacturing an infrared sensor, which can suppress the noise, obtain excellent sensor sensitivity and sensor quality, and have excellent yield and productivity at low cost.

In order to solve the above problems, the infrared sensor of the present disclosure adopts the configuration shown below.
[1] In the infrared sensor according to one aspect of the present disclosure, a first metal bonding film provided on the upper surface side of the first substrate and a second metal bonding film provided on the lower surface side of the second substrate are bonded. A thermopile-type infrared sensor is provided in which a sealed space is ensured by a thermopile type infrared sensor, in which the second metal bonding film is connected to a cooling layer provided on the first substrate on the lower surface side of the second substrate. The infrared sensor is characterized by having an infrared ray blocking part that is spaced apart from the contact and extends to a position facing at least a portion of the cold contact.

According to this aspect, the second metal bonding film extends on the lower surface side of the second substrate to a position facing at least a portion of the cold contact while being separated from the cold contact provided on the first substrate. By having the infrared ray blocking section, it is possible to suppress infrared rays incident on the infrared sensor from the outside from reaching the cold junction. This suppresses the rise in temperature of the cold junction, maintains the temperature difference between the hot and cold junctions when infrared rays are incident, and prevents the output signal from the infrared sensor from decreasing. This makes it possible to increase the sensitivity of the device.
Furthermore, the infrared ray blocking section provided on the lower surface side of the second substrate is formed by extending the second metal bonding film, and can be formed simultaneously and integrally with the second metal bonding film. , there is no need to provide a new member for blocking infrared rays, and there is no need to add a new process, resulting in excellent productivity. Thereby, an infrared ray blocking structure can be realized with a simple and inexpensive configuration without complicating the manufacturing process. Further, since there is no need to add new members, there is no deterioration in the quality of the infrared sensor or difficulty in manufacturing control, and the yield is improved.

[2] In the infrared sensor according to the aspect of [1] above, the infrared blocking section is arranged on the lower surface side of the second substrate, while being spaced apart from the cold junction provided on the first substrate. More preferably, it extends to a position facing the.

According to the infrared sensor of this aspect, as described above, the infrared shielding part formed by extending the second metal bonding film extends to the opposing position so as to cover the entire cold junction, so that the external It is possible to more effectively suppress infrared rays incident on the infrared sensor from reaching the cold junction.

[3] In the infrared sensor according to the aspect [1] or [2] above, the second substrate corresponds to the infrared ray blocking section so as to separate the infrared ray blocking section from the cold contact on the first substrate. It is preferable that the position is a spaced region dug from the lower surface side.

According to the infrared sensor of this aspect, as described above, the position corresponding to the infrared ray blocking part on the second substrate is a spaced area provided so as to be dug from the bottom surface side of the second substrate. The infrared ray blocking section formed by extending the second substrate and the second metal bonding film can be reliably separated from the cold contact without interfering with the cold contact. Thereby, it is possible to reliably suppress infrared rays incident from the outside from reaching the cold junction, and to effectively suppress the rise in temperature of the cold junction and its vicinity. Further, since no stress is applied due to the film formation of the additional member, damage to the thermopile type infrared detection element can be avoided.

[4] In the infrared sensor according to the aspect [3] above, a concave cavity portion for forming the sealed space is provided on the lower surface side of the second substrate, and the spaced region is It is possible to employ a configuration in which a stepped shape is provided between the lower surfaces of the two substrates and the cavity portion.

According to the infrared sensor of this aspect, as described above, the separation area provided on the second substrate has a stepped shape provided between the lower surface of the second substrate and the cavity portion, so that the second The infrared ray blocking section formed by extending the substrate and the second metal bonding film can be separated more reliably without interfering with the cold junction. Thereby, it is possible to more reliably suppress infrared rays incident from the outside from reaching the cold junction, and more effectively suppress the rise in temperature of the cold junction and its vicinity.

[5] In the infrared sensor according to the aspect [3] above, the separation region has a slope shape that is gradually inclined between the lower surface of the second substrate and the cavity portion. Can be adopted.

According to the infrared sensor of this aspect, as described above, the separation area provided on the second substrate has a slope shape that is gradually inclined between the lower surface of the second substrate and the cavity portion. As a result, similarly to the above, the second substrate and the infrared ray blocking section can be reliably separated from each other without interfering with the cold junction. Thereby, it is possible to reliably suppress infrared rays incident from the outside from reaching the cold junction, and to effectively suppress the rise in temperature of the cold junction and its vicinity. Further, compared to the case where the separated region is a step, no shadow is caused by the step when forming the infrared ray blocking portion, so that a uniform infrared ray blocking portion can be formed more reliably.

[6] In the infrared sensor according to the aspect of [5] above, the second substrate is made of a silicon substrate, and the slope-shaped spaced region provided on the second substrate wets the (100) plane of the silicon substrate. An inclined surface formed by the (111) plane of the silicon substrate that appears by etching silicon anisotropically, and the inclination angle of the inclined surface is an angle derived from the crystal anisotropy of the silicon substrate. It is also possible to adopt the configuration described above.

According to the infrared sensor of this embodiment, first, since the second substrate is made of a silicon substrate that has excellent workability, the precision when processing by wet etching is improved. Further, by employing a silicon substrate whose plane orientation is (100), which is generally available, it is easy to obtain and it is possible to suppress manufacturing costs.
Further, the slope-shaped separated region provided on the second substrate is an inclined surface formed by the (111) plane of the silicon substrate that appears by performing silicon anisotropic etching on the (100) plane of the silicon substrate by wet etching. Since the inclination angle of this inclined surface is an angle derived from the crystal anisotropy of the silicon substrate, that is, an inclination of approximately 54.7°, the inclined surface has a stable angle. As a result, the second board and the infrared cutoff part can be more reliably separated without interfering with the cold junction, so that the infrared rays incident from the outside can be reliably suppressed from reaching the cold junction. It is possible to more effectively suppress an increase in temperature at the contact point and its vicinity.

[7] In the infrared sensor according to any of the aspects [1] to [6] above, the first substrate and the second substrate are rectangular in plan view, and the first substrate is provided with an electrode. Adopting a configuration in which an electrode placement area is placed on the outside in a plan view on the top surface side, and the electrode placement area is placed along at least one side of the first substrate and the second substrate in a plan view. You may.

According to the infrared sensor of this aspect, the electrode arrangement area for providing the electrodes may be provided, for example, only on one side of the first substrate, or may be further provided on the other side opposite to this one side. For example, it can be used flexibly to save space when COBing an infrared sensor to a printed circuit board, etc., or to be applied to a chip on which an infrared sensor's signal amplification circuit, signal input/output control circuit, etc. are mixed. It can be configured as follows. Therefore, for example, if the electrode arrangement area is provided only on one side of the first substrate, it is possible to downsize the printed circuit board on which the infrared sensor is mounted, and furthermore, the electrode arrangement area can be provided on the other side. If provided, it becomes possible to support more complicated electrical connections.

[8] A method for manufacturing an infrared sensor according to one aspect of the present disclosure includes a step (1) of etching the surface of a substrate material to form a concave device region on one side to obtain a first substrate; By etching the surface of the material, a penetration region is formed in at least a portion of the substrate material, and a concave cavity portion is formed on the lower surface side that will be the bonding surface with the first substrate, and further, in a plan view, a step (2) of forming a joint portion provided so as to surround the cavity portion to obtain a second substrate; and a step (2) of forming a joint portion provided to surround the cavity portion to obtain a second substrate; a step (3) of forming a first metal bonding film at a position corresponding to the bonded portion, and a step of arranging an electrode in the electrode placement region on one surface side of the first substrate obtained in step (1). (4), a step (5) of arranging a thermopile-type infrared detection element in the device region of the first substrate obtained in step (1), and the second substrate obtained in step (2). a step (6) of forming a second metal bonding film so as to cover a position to be bonded to the first substrate in the bonding portion; The first substrate and the second substrate are overlapped so that the first substrate and the second substrate are arranged, and the first metal bonding film and the second metal bonding film are bonded to each other by applying pressure to each other. A step (7) of bonding the first substrate and the second substrate while securing the sealing space, and cutting the first substrate along dicing lines to separate the first substrate into chips. Step (8), the step (5) includes forming a membrane thin film so as to cover the opening of the device region in the first substrate, and then placing at least a portion of the thermocouple on the membrane thin film. the thermopile by arranging the cold junction, which is part of the thermocouple, outside the opening of the device region, and arranging the hot junction, which is part of the thermocouple, on the membrane thin film. type infrared detection element, and in step (6), the second metal bonding film is placed on the lower surface side of the second substrate while separating it from the cold junction provided on the first substrate. This is a method of manufacturing an infrared sensor, characterized in that the infrared sensor is formed to have an infrared blocking portion extending to a position facing at least a portion of a cold contact.

According to this aspect, in step (6), the second metal bonding film is placed on the lower surface side of the second substrate, while separating the second metal bonding film from the cold contact provided on the first substrate, and facing at least a part of the cold contact. By forming the infrared ray blocking portion to extend to the position where the cold junction is located, it is possible to manufacture an infrared sensor having a structure that can suppress infrared rays incident from the outside from reaching the cold junction.
In addition, by forming the infrared ray blocking part provided on the lower surface of the second substrate by extending the second metal bonding film, it is possible to form the infrared ray blocking part at the same time and integrally with the second metal bonding film. There is no need to provide new members or add new processes, and excellent productivity can be achieved.
This makes it possible to manufacture an infrared sensor with excellent sensor sensitivity and yield with good productivity and at low cost.

[9] In the method for manufacturing an infrared sensor according to the aspect of [8] above, the step (6) adopts a method of integrally forming the entire second metal bonding film including the infrared blocking portion in the same step. can.

According to the method for manufacturing an infrared sensor of this aspect, as described above, step (6) forms the entire second metal bonding film including the infrared blocking portion in the same step, thereby reducing the time required for step (6). can be reduced. This further increases productivity and makes it possible to manufacture infrared sensors at lower cost.

[10] In the method for manufacturing an infrared sensor according to the aspect [8] above, in the step (6), at least the portion of the infrared ray blocking portion of the second metal bonding film is removed from the infrared sensor in the step (2). A method can be adopted in which the spaced regions are formed simultaneously on two substrates.

According to the method for manufacturing an infrared sensor of this aspect, as described above, at least the infrared ray blocking portion of the second metal bonding film is formed at the same time as the separated region formed on the second substrate, so that each step The time required can be reduced. This further increases productivity and makes it possible to manufacture infrared sensors at even lower cost.

[11] In the method for manufacturing an infrared sensor according to the aspect [8] above, in the step (2), a silicon substrate is used as the material of the second substrate, and the infrared blocking portion of the second metal bonding film is a slope that gradually slopes between the lower surface of the second substrate and the cavity portion at a position corresponding to the infrared ray blocking portion on the second substrate so as to be spaced apart from the cold contact on the first substrate; In addition to forming the slope-shaped spaced region as a sloped surface formed by the (111) plane of the silicon substrate that appears by wet etching silicon anisotropically on the (100) plane of the silicon substrate. , and the method may be such that the inclination angle of the inclined surface is an angle derived from crystal anisotropy of the silicon substrate.

According to the method for manufacturing an infrared sensor of this embodiment, as described above, in step (2), firstly, by using a silicon substrate with excellent workability as the material of the second substrate, the accuracy when processing by wet etching is improved. will improve. Further, by employing a silicon substrate whose plane orientation is (100), which is generally available, it is easy to obtain and it is possible to suppress manufacturing costs.
Further, in step (2), the position corresponding to the infrared ray blocking part on the second substrate is moved to the second substrate so that the infrared ray blocking part of the second metal bonding film is spaced apart from the cold contact on the first substrate. By forming a slope that gradually slopes between the lower surface and the cavity part, the infrared shielding part formed by extending the second substrate and the second metal bonding film can be made more secure without interfering with the cold junction. can be spaced apart.
Furthermore, in step (2), the (111) plane of the silicon substrate, which appears by performing silicon anisotropic etching on the (100) plane of the silicon substrate by wet etching, forms the slope-shaped separated region to be formed on the second substrate. By setting the slope angle of this slope to an angle derived from the crystal anisotropy of the silicon substrate, that is, approximately 54.7°, it is possible to form a slope shape with a stable angle. . Thereby, it is possible to form a separation area in which the second substrate and the infrared shielding part are separated more reliably without interfering with the cold junction.

According to the present disclosure, by providing the above configuration, it is possible to suppress infrared rays incident on the infrared sensor from the outside from reaching the cold junction, and to suppress the temperature of the cold junction from increasing. This makes it possible to maintain the temperature difference between the hot junction and the cold junction when infrared rays are incident, and to prevent the output signal from the infrared sensor from decreasing, thereby making it possible to increase the sensitivity of the infrared sensor.
Furthermore, the infrared ray blocking section provided on the lower surface side of the second substrate is formed by extending the second metal bonding film, and can be formed simultaneously and integrally with the second metal bonding film. , there is no need to provide a new member for blocking infrared rays, and there is no need to add a new process, resulting in excellent productivity. Thereby, an infrared ray blocking structure can be realized with a simple and inexpensive configuration without complicating the manufacturing process. Further, since there is no need to add new members, there is no deterioration in the quality of the infrared sensor or difficulty in manufacturing control, and the yield is improved.
Therefore, it is possible to provide an infrared sensor and a method for manufacturing an infrared sensor that provides excellent sensor sensitivity, low cost, and excellent yield and productivity.

FIG. 1 is a plan view schematically illustrating an infrared sensor according to a first embodiment of the present disclosure. 1 is a diagram schematically illustrating an infrared sensor according to a first embodiment of the present disclosure, and is a sectional view taken along line AA shown in FIG. 1. FIG. FIG. 3 is a diagram schematically illustrating the method for manufacturing an infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing the procedure of step (2) of obtaining a second substrate. FIG. 3 is a diagram schematically illustrating the method for manufacturing an infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing the procedure of step (2) of obtaining a second substrate. FIG. 3 is a diagram schematically illustrating the method for manufacturing an infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing the procedure of step (2) of obtaining a second substrate. FIG. 3 is a diagram schematically illustrating the method for manufacturing an infrared sensor according to the first embodiment of the present disclosure, and is a process diagram showing the procedure of step (2) of obtaining a second substrate. FIG. 2 is a diagram schematically illustrating a method for manufacturing an infrared sensor according to a first embodiment of the present disclosure, in which a second metal bonding film is formed at a position where a bonding portion of a second substrate is bonded to the first substrate; FIG. 7 is a process diagram showing the procedure of step (6) of forming an infrared shielding portion extending from the second metal bonding film. FIG. 2 is a diagram schematically illustrating a method for manufacturing an infrared sensor according to a first embodiment of the present disclosure, in which step (1) of obtaining a first substrate, a bonding portion of a second substrate is placed on one side of the first substrate; A step (3) of forming a first metal bonding film at a corresponding position, a step (4) of arranging an electrode in an electrode arrangement region on one side of the first substrate, and a step (4) of forming a thermopile-type infrared detection film in a device region of the first substrate. It is a process diagram which shows the procedure of process (5) of arranging an element. FIG. 2 is a diagram schematically illustrating a method for manufacturing an infrared sensor according to a first embodiment of the present disclosure, including a step (7) of bonding a first substrate and a second substrate to obtain an infrared sensor, and a dicing line. FIG. 7 is a process diagram showing the procedure of a step (8) of dividing the first substrate and the second substrate into individual chips by cutting the first substrate and the second substrate along the lines. FIG. 2 is a cross-sectional view schematically illustrating an infrared sensor according to a second embodiment of the present disclosure. FIG. 7 is a plan view schematically illustrating an infrared sensor according to a third embodiment of the present disclosure. 6 is a diagram schematically illustrating an infrared sensor according to a third embodiment of the present disclosure, and is a cross section taken along the line BB shown in FIG. 5. FIG.

Hereinafter, embodiments of an infrared sensor and an infrared sensor manufacturing method of the present disclosure will be listed, and the configuration thereof will be described with appropriate reference to FIGS. 1 to 6. Note that each drawing used in the following explanation may show characteristic parts enlarged for convenience in order to make it easier to understand the characteristics of the infrared sensor of the present disclosure, and the dimensional ratios of each component may differ from the actual size. It may be different. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present disclosure is not limited thereto, and can be implemented with appropriate changes within the scope of the gist thereof.

<First embodiment>
Below, an infrared sensor and a method for manufacturing the same according to a first embodiment of the present disclosure will be described in detail with appropriate reference to FIGS. 1, 2, and 3A to 3G.
FIG. 1 is a plan view schematically explaining the infrared sensor 1 of this embodiment, and FIG. 2 is a cross-sectional view taken along the line AA of the infrared sensor 1 shown in FIG. Further, FIGS. 3A to 3G are diagrams illustrating the method for manufacturing the infrared sensor 1 of this embodiment, and are process diagrams showing the procedure of each step.

[Infrared sensor configuration]
As shown in FIGS. 1 and 2, the infrared sensor 1 of this embodiment first includes a first substrate 2 (base substrate) and a second substrate 3 (lid substrate).
In addition to the first substrate 2 and the second substrate 3 described above, the infrared sensor 1 of the present embodiment further includes a thermopile disposed within a device region 22 formed on the upper surface (one surface) 2a of the first substrate 2. It has a general configuration including a type infrared detection element 4.

To explain in more detail, the infrared sensor 1 of this embodiment first includes an infrared sensor package including the first substrate 2 and the second substrate 3 described above.
Furthermore, the infrared sensor 1 of the present embodiment includes a thermopile-type infrared detection element (hereinafter sometimes simply referred to as a thermopile element) 4 disposed in the device region 22 of the first substrate 2 and a Electrodes 81 and 82 arranged in the electrode arrangement regions 23a and 23b; 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; A second metal bonding film 52 is provided so as to cover the bottom surface 31a of the bonding portion 31 of the second substrate 3, which is the position to be bonded to the first substrate 2.
In the infrared sensor 1 of this embodiment, the thermopile element 4 described above is arranged in the device region 22 of the first substrate 2. More specifically, a membrane thin film 4a is provided so as to cover the opening 22a of the device region 22, a thermocouple 41 at least partially disposed on the membrane thin film 4a, and a portion of this thermocouple 41. It has a cold junction 42 disposed outside the opening 22a of the device region 22, and a hot junction 43, which is part of the thermocouple 41 and disposed on the membrane thin film 4a.
Further, in the infrared sensor 1 of the present embodiment, the second metal bonding film 52 provided on the second substrate 3 is connected to the cold contact 42 provided on the upper surface 2a of the first substrate 2 on the lower surface 3a side of the second substrate 3. It has an infrared shielding part 52A that extends to a position facing at least a part of the cold contact 42 while being separated from the cold contact 42.
In the infrared sensor 1 of this embodiment, the first metal bonding film 51 and the second metal bonding film 52 are bonded by, for example, metal diffusion bonding, thereby ensuring a cavity C on the thermopile element 4. However, it is configured as a thermopile type infrared sensor in which a first substrate 2 and a second substrate 3 are joined.
Hereinafter, each configuration of the infrared sensor 1 of this embodiment will be explained in more detail.

The first substrate 2 is a base substrate of an infrared sensor package that constitutes the infrared sensor 1, and is made of, for example, a silicon substrate. Further, in the example shown in FIG. 1, the first substrate 2 is formed into a rectangular shape when viewed from above. Further, on the upper surface 2a (one surface) of the first substrate 2, a device region 22 for arranging a thermopile element 4, which will be described in detail later, is formed in a concave shape. A region 22 is provided. Further, on the upper surface 2a of the first substrate 2, an electrode arrangement region 23a is provided which is arranged outside the device region 22 in plan view.

The first substrate 2 can be obtained by forming the device region 22 by wet etching a silicon substrate, for example. The device region 22 is, for example, a region formed in a rectangular shape in plan view.
Note that the planar view shape of the first substrate 2 is not limited to the roughly rectangular shape as shown in the illustrated example, and it is also possible to adopt other shapes according to the planar view shape of the infrared sensor 1. .
Furthermore, in the example described in this embodiment, the upper surface 2a and lower surface 2b of the first substrate 2 are configured to be approximately flat except for the device region 22.
Further, the first substrate 2 can also be obtained by forming the device region 22 by dry etching a silicon substrate.

The first substrate 2 also includes an embedded wiring 71 that is embedded in the first substrate 2 and electrically connected to the thermopile element 4, and a second substrate that is disposed facing each other on the first substrate 2. An electrode 81 is provided on the outer side and on one side of the electrode 3 in plan view and is electrically connected to the embedded wiring 71 via the first contact 91a.
Although detailed illustrations are omitted in FIGS. 1 and 2, the second contact 91b and the thermopile element 4 are electrically connected via the first signal wiring section 61. Accordingly, the electrode 81 is configured to be able to send out the detection signal output from the thermopile element 4 to the outside.

Although not shown in FIGS. 1, 2, etc., in the infrared sensor 1 of this embodiment, the area around the device area 22 on the first substrate 2 and the area around the embedded wiring 71 or electrode 81, which will be described later, is etc., an insulating layer may be further provided. Specifically, the insulating layer (not shown) can be provided in a region outside the thermopile element 4 on the upper surface 2a side of the first substrate 2 so as to surround the thermopile element 4 in a plan view. This insulating layer is made of an insulating material, for example, 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 (lid) of the infrared sensor 1, and like the first substrate 2, it is obtained by etching a silicon substrate. Further, the second substrate 3 in the illustrated example is formed into a rectangular shape in plan view, similarly to the first substrate 2.
More specifically, the second substrate 3 is bonded to the upper surface 2a side of the first substrate 2 so as to cover the device region 22, and the lower surface 3a side, which is the bonding surface with the first substrate 2, is bonded to the upper surface 2a side of the first substrate 2. It has a concave cavity part 32 for securing a cavity C between it and the device region 22, and a joint part 31 provided in a generally frame shape so as to surround the cavity part 32 in plan view.
Further, the second substrate 3 has at least a part of the outer side of the joint portion 31 when viewed from above, and in the illustrated example, the second substrate 3 has a rectangular shape when viewed from above, and has one side and the other side facing each other. Along the same line, there is a through area 33 for exposing the electrode arrangement area 23a of the first substrate 2.
In the example shown in FIGS. 1 and 2, the penetration region 33 is arranged on one side at a position corresponding to the electrode arrangement region 23a. Further, in the illustrated example, the cavity portion 32 has a rectangular shape in plan view.

Further, in the example shown in FIG. 2, the second substrate 3 has a position corresponding to the infrared ray blocking portion 52A carved from the bottom surface 3a side so as to separate the infrared ray blocking portion 52A from the cold contact 42 on the first substrate 2. A spaced area 34 is provided so as to be inserted into the space. In the illustrated example, the separation region 34 has a stepped shape provided between the lower surface 3a of the second substrate 3 and the cavity portion 32. The height dimension of the step when the separation region 34 is formed into a step shape is not particularly limited, but is equal to the cold junction between the second substrate 3, the infrared ray blocking section 52A, and the thermopile element 4 disposed on the upper surface 2a of the first substrate 2. From the viewpoint of ensuring a sufficient distance from 42, it is preferable to set the distance to about 5 to 10 μm, for example.

Further, the separation area 34 provided on the lower surface 3a side of the second substrate 3 is not limited to a stepped shape as shown in the illustrated example. Although detailed illustrations are omitted, the spaced apart area provided on the second substrate 3 is configured to have a slope shape that is gradually inclined between the lower surface 3a of the second substrate 3 and the cavity portion 32, for example. You can also use it as
In addition, when the spaced apart region provided on the second substrate 3 is formed into a sloped shape, the sloped shape can be formed by, for example, silicon anisotropic etching of the (100) plane of the silicon substrate used as the second substrate 3 by wet etching. It is also possible to create an inclined surface formed by the (111) plane of the silicon substrate. In this case, the inclined plane of the separation region has an angle of inclination derived from the crystal anisotropy of the silicon substrate, that is, an inclination of approximately 54.7°.

In the present embodiment, the second metal bonding film 52 is spaced apart from the cold contact 42 provided on the first substrate 2 on the lower surface 3a side of the second substrate 3, while at least a portion of the cold contact 42 is provided on the first substrate 2. It has an infrared ray blocking section 52A extending to a position facing the . In the example shown in FIGS. 1, 2, etc., the infrared cutoff section 52A is separated from the cold contact 42 provided on the top surface 2a of the first substrate 2 on the lower surface 3a side of the second substrate 3, while It extends to the opposite position so as to cover the entire area.

In the second substrate 3, for example, the joint portion 31, the penetration region 33, and the separation region 34 can be formed by dry etching the silicon substrate, and the cavity portion 32 can be formed by wet etching the silicon substrate. be.
Alternatively, the second substrate 3 can also be obtained by simultaneously forming the joint portion 31, the cavity portion 32, the penetrating region 33, and the spacing region 34 in the same process, for example, by forming all of them by wet etching.

The second substrate 3 is superimposed on the first substrate 2 so as to be approximately parallel to the first substrate 2.
Similarly to the case of the first substrate 2, the shape of the second substrate 3 in plan view is not limited to the approximately rectangular shape shown in the illustrated example, but may be shaped like the first substrate 2 in accordance with the shape of the infrared sensor 1 in plan view. It can have a corresponding shape.
Furthermore, the second substrate 3 is made of a silicon substrate that can transmit far infrared rays, so that it is configured to allow far infrared rays to enter the thermopile element 4 .

The depth of the cavity part 32 in the second substrate 3, that is, the height of the frame-shaped joint part 31, is not particularly limited as long as it can secure a space having a certain capacity as the cavity C. For example, The height can be from 30 to 100 μm.

In addition, the planar dimension (area) of the bottom surface 31a of the bonding portion 31 is not particularly limited, but the bonding strength due to metal diffusion bonding between the first metal bonding film 51 and the second metal bonding film 52, which will be described in detail later, is Taking into consideration the security of the space, it may have a generally rectangular shape of 1.5 to 4.0 mm square, for example.

Furthermore, in this embodiment, by using a silicon substrate for the second substrate 3, the transmittance of far infrared rays in the second substrate 3 is increased, and it becomes possible to efficiently receive far infrared rays.
In addition, by using silicon substrates with excellent workability for both the first substrate 2 and the second substrate 3, the accuracy when processing by dry etching or wet etching is improved, resulting in even better device characteristics. Become.
In addition, by using commonly available silicon substrates, especially those with (100) plane orientation, as the first substrate 2 and second substrate 3, they are easily available and can reduce manufacturing costs. It becomes possible to do so.

As described above, the thermopile element 4 is arranged in the concave device region 22 formed on the upper surface 2a side of the first substrate 2. Further, as described above, the thermopile element 4 is provided so as to send out its detection signal from the electrode 81 to the outside, and when installed in the device area 22 of the first substrate 2, the upper surface of the thermopile element 4 is The side is provided so as to be exposed to the cavity C which is a reduced pressure space.

The thermopile element 4 includes a membrane thin film 4a provided to cover the opening 22a of the device region 22, a thermocouple 41 at least partially disposed on the membrane thin film 4a, and a part of the thermocouple 41. , has a cold junction 42 disposed outside the opening 22a of the device region 22, and a hot junction 43, which is part of the thermocouple 41 and disposed on the membrane thin film 4a. Further, in the illustrated example, an infrared absorbing film 4b is laminated on the membrane thin film 4a, and this infrared absorbing film 4b is formed to cover the membrane thin film 4a and the thermocouple 41.

As described above, the membrane thin film 4a is a thin film that is provided to cover the opening 22a and supports the thermocouple 41 arranged in a membrane structure.
The material for the membrane thin film 4a is not particularly limited, but in consideration of various mechanical properties and electrical properties, for example, a silicon oxide film such as silicon dioxide (SiO ₂ ), a silicon nitride film (SiN _x ), Furthermore, a laminated film of these can be used.
Further, the thickness of the membrane thin film 4a is not particularly limited, but from the viewpoint of having strength enough to support the thermocouple 41 and minimizing the influence of temperature on the thermocouple 41, for example, 1. The thickness can be approximately 2 μm.

As described above, the infrared absorbing film 4b is formed on the membrane thin film 4a so as to cover the membrane thin film 4a and the thermocouple 41 provided thereon. Accordingly, in the example shown in FIG. 2 and the like, the infrared absorbing film 4b is formed so as to also cover the hot junction 43, which will be described in detail later.

The infrared absorbing film 4b has the function of efficiently introducing infrared rays incident on the infrared sensor 1 toward the thermocouple 41.
The material of the infrared absorbing film 4b is not particularly limited, and materials commonly used in this field can be used, and for example, a black gold film, a resin material, etc. are suitable.

As shown in the example shown in FIG. 1, the thermocouple 41 has a configuration in which a first thermocouple 41a and a second thermocouple 41b, each made of a different metal, are arranged alternately in a comb-like shape and connected in series. ing. In the thermocouple 41, the contact points between the first thermocouple 41a and the second thermocouple 41b are a cold junction 42 and a hot junction 43, which will be described later, respectively. , the intensity of infrared rays is detected by detecting the temperature difference between the cold junction 42 and the hot junction 43.

The material for the thermocouple 41 is not particularly limited, and metal materials conventionally used for thermocouples can be used without any restrictions. For example, p-type polysilicon can be used as the material for the first thermocouple 41a, and in this case, n-type polysilicon is used as the material for the second thermocouple 41b.

As described above, the cold junction 42 is a contact point between the first thermocouple 41a and the second thermocouple 41b in the thermocouple 41, is provided outside the device region 22 in plan view, and is located on the top surface of the first substrate 2. 2a. In this embodiment, the cold junction 42 is arranged at a position where infrared rays incident from the outside are blocked by an infrared ray blocking section 52A, the details of which will be described later.

As described above, the hot junction 43 is also a contact point between the first thermocouple 41a and the second thermocouple 41b in the thermocouple 41, and is arranged on the membrane thin film 4a. Unlike the cold junction 42, the hot junction 43 is not affected by the infrared rays blocked by the infrared rays blocking section 52A, and is arranged on the membrane thin film 4a at a position where infrared rays are efficiently incident.

As described above, the first metal bonding film 51 is provided at a position corresponding to the bonding portion 31 of the second substrate 3 on the upper surface 2a of the first substrate 2.
Furthermore, as described above, the second metal bonding film 52 is provided to cover the position of the bonding portion 31 of the second substrate 3 where it is bonded to the first substrate 2, that is, the bottom surface 31a. Furthermore, in the infrared sensor 1 of the present embodiment, the second metal bonding film 52 is extended inward in a plan view on the lower surface 3a of the second substrate 3, so that at least a portion of the cold junction 42 is connected to the second metal bonding film 52. The infrared rays blocking portion 52A is formed so as to cover the infrared rays while being spaced from each other.

In this embodiment, the first metal bonding film 51 provided on the first substrate 2 and the second metal bonding film 52 provided on the second substrate 3 are bonded by metal diffusion bonding, for example. A body 50 is formed, and the first substrate 2 and the second substrate 3 are bonded 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 rectangular frame shape in a plan view, and the first metal bonding film 51 and the second metal bonding film 52 The metal bonded body 50 formed by metal diffusion bonding is also formed into a rectangular frame shape in plan view.
Further, the metal bonding body 50 consisting of the first metal bonding film 51 and the second metal bonding film 52 is formed by bonding the first substrate 2 and the second substrate 3. and a cavity C surrounded by the metal bonded body 50 is formed.

More specifically, the metal bonded body 50 includes 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. A first metal bonding film 51, a second base layer 52a disposed at the tip of the joint portion 31 of the second substrate 3, and a second bonding layer 52b laminated on the second base layer 52a. It is composed of two metal bonding films 52.

The first base layer 51a and the second base layer 52a are provided to be bonded to the top surface 2a of the first substrate 2 or the bottom surface 31a of the joint portion 31 of the second substrate 3, respectively. By providing each base layer as described above, 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. is joined to.

The first base layer 51a and the second base layer 52a are formed in a thin film shape from a conductive metal material on the upper surface 2a of the first substrate 2 or at the tip of the joint portion 31 of the second substrate 3. .
The materials for the first base layer 51a and the second base layer 52a are not particularly limited, but are preferably thin films made of tantalum (Ta) or titanium nitride (TiN), for example.
Further, the first base layer 51a provided on the first substrate 2 side is connected to, for example, a ground (not shown). This ground can be provided, for example, on 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.

The first bonding layer 51b and the second bonding layer 52b are stacked on the first base layer 51a or the second base layer 52a, respectively, as described above.
The material for 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 for the first base layer 51a and the second base layer 52a, the first bonding layer 51b And gold (Au) is used as the material of the second bonding layer 52b. Furthermore, when titanium nitride is used as the material for the first base layer 51a and the second base layer 52a, aluminum (Al) is used as the material for 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 using the same material. That is, the first bonding layer 51b and the second bonding layer 52b are configured to both include 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 materials, the thickness of each layer is not particularly limited. On the other hand, in consideration of electrical characteristics and strength during bonding, 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, For example, the range is {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}. It is preferable to do so.
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, for example, {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}.

Also, the sealing width for the cavity C by the metal bonding body 50, that is, the maximum width of the second metal bonding film 52 and the first metal bonding film 51, which are formed in a rectangular shape in plan view corresponding to the bonding portion 31, is as follows. Not particularly limited. On the other hand, when considering improving the bondability of this part and further increasing the sealing airtightness of the cavity C, the maximum widths of the first metal bonding film 51 and the second metal bonding film 52 are the same as those of the first base layer 51a and When the second base layer 52a is made of tantalum and the first bonding layer 51b and the second bonding layer 52b are made of gold, the thickness is preferably 0.10 to 0.30 mm, for example. Further, 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 second metal bonding film 52 and the first metal The maximum width of the bonding film 51 is preferably, for example, 0.03 to 0.1 mm.
Note that the sealing width (junction width) described in this embodiment is a dimension that does not include the portion of the infrared ray blocking portion 52A extending from the second metal bonding film 52.

In this embodiment, the first metal bonding film 51 and the second metal bonding film 52 constituting the metal bonding body 50 have the layered structure described above, so that the first substrate 2 and the second substrate 3 can be connected to each other. When they are stacked and pressed, metal diffusion bonding is developed between the first base layer 51a and first bonding layer 51b and the second base layer 52a and second bonding layer 52b. This makes it possible to make 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, when bonding the first substrate 2 and the second substrate 3, the first metal bonding film 51 and the second metal bonding film 52 are made of the above materials and metal diffusion bonding is performed. Not limited. For example, 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 Au--Sn eutectic bonding may be employed. In this case, for example, the first base layer 51a and the second base layer 52a, and the first bonding layer 51b and the second bonding layer 52b are each formed from an Au-Sn eutectic alloy, and heated and melted to the eutectic temperature. By doing so, a eutectic bond is formed between the first base layer 51a and the first bonding layer 51b and the second base layer 52a and the second bonding layer 52b. Thereby, the first substrate 2 and the second substrate 3 can be firmly and stably joined, and the cavity C can be sealed and hermetically sealed.

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, one containing 20 to 22% of Au-Sn. Can be used.
Further, the thickness of each layer of the first metal bonding film 51 and the second metal bonding film 52 in this case is not particularly limited, but may be configured in a paste or ribbon shape having a thickness of 5 to 10 μm, for example.
Also, regarding the sealing width when the first metal bonding film 51 and the second metal bonding film 52 are Au-Sn eutectic bonded, that is, the width of the first metal bonding film 51 and the second metal bonding film 52. Although not particularly limited, it can be, for example, in the range of 0.1 to 0.5 mm.

As described above, the infrared shielding portion 52A is a metal film that is integrally formed as a part of the second metal bonding film 52 by extending the second metal bonding film 52.
In the infrared sensor 1 of this embodiment, by providing the infrared ray blocking section 52A, infrared rays incident on the infrared sensor 1 are suppressed from going toward the cold junction 42, and the temperature of the cold junction 42 is prevented from increasing. By avoiding this, a temperature difference between the cold junction 42 and the hot junction 43 is ensured, and sensor sensitivity is increased.

The infrared shielding portion 52A is a metal film extending from the second metal bonding film 52 along the lower surface 3a of the second substrate 3, and in the example shown in FIG. has been done. Therefore, the material and layer structure of the infrared shielding section 52A are the same as those of the second metal bonding film 52 described above.
Further, the thickness of the infrared ray blocking portion 52A is not particularly limited, but by making it approximately the same as the above-mentioned thickness of the second metal bonding film 52, sufficient infrared ray blocking ability can be ensured.

In the example shown in FIGS. 1 and 2, the infrared ray blocking portion 52A faces the cold junction 42 of the thermopile element 4 provided on the first substrate 2 side while covering the surface of the separation region 34 having the above-described end face shape. formed in position. Further, the infrared ray blocking section 52A is provided in an encircling shape in plan view so as to surround the cavity 32 while covering the surface of the end-shaped separation region 34.

The dimensions and shape of the infrared ray blocking section 52A are not particularly limited, but are preferably dimensions and shapes that can suppress infrared rays from going toward the cold junction 42 of the thermopile element 4 provided on the first substrate 2 side. As shown in the example shown in FIG.
On the other hand, in this embodiment, from the viewpoint of ensuring high sensor sensitivity, the infrared ray blocking portion 52A extending from the second metal bonding film 52 overlaps with the membrane structure of the thermopile element 4 provided on the first substrate 2 side. It is more preferable that the thermocouple 41 including the hot junction 43 be provided at a location where the thermocouple 41 including the hot junction point 43 does not overlap the membrane thin film 4a provided on the surface.

The above-mentioned electrode 81, embedded wiring 71, first contact 91a, and second contact 91b are provided on the upper surface 2a of the first substrate 2.

The embedded wiring 71 electrically connects the thermopile element 4 and the electrode 81, as described above. A plurality of embedded wirings 71 are provided according to the number of electrodes 81 and output terminals (not shown) of the thermopile element 4, and in FIG. 2, only a part of the embedded wirings 71 are shown. Further, the electrode 81 is electrically connected to the thermopile element 4 via the first signal wiring section 61. Further, the embedded wiring 71 in the illustrated example is buried above the center part in the thickness direction of the first substrate 2, and is arranged so as to extend below the electrode 81 and the first signal wiring section 61. There is.

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

The electrode 81 is electrically connected to the thermopile element 4 via the embedded wiring 71, the first contact 91a, etc., and outputs a detection signal etc. from the thermopile element 4 to the outside. The electrodes 81 are provided along opposing edges in the electrode placement area 23a secured on the upper surface 2a of the first substrate 2, and in the illustrated example, the electrodes 81 are provided at two locations. . Further, the electrode 81 is provided so as to be exposed from the second substrate 3 on the outside of the second substrate 3 which is provided opposite to the first substrate 2 in plan view. The electrode 81 is provided so as to be electrically connectable to various external devices that require detection signals from the thermopile element 4, for example.

As the material of the electrode 81, any metal material conventionally used in this field can be used without any restrictions; for example, aluminum silicon alloy (AlSi) and titanium nitride (TiN) are sequentially laminated by a sputtering method. etc. can be used.
Further, as will be described in detail later, when the electrode 81 is formed simultaneously with the first metal bonding film 51 in the same process, the same material as the first metal bonding film 51 described above is used as the material for each of these electrodes. Bye.

The first contact 91a is for electrically connecting the embedded wiring 71 and the electrode 81, and the second contact 91b is for electrically connecting the embedded wiring 71 and the first signal wiring section 61. In the example shown in FIG. 2, the first contact 91a is connected to one end of the buried wiring 71, and the second contact 91b is connected to the other end of the buried wiring 71.

As described above, the thermopile element 4 is electrically connected to the electrode 81 via the first signal wiring section 61, the second contact 91b, the embedded wiring 71, and the first contact 91a.

The materials constituting the first contact 91a and the second contact 91b are not particularly limited, and metal materials conventionally used in this field can be used without any restrictions.
Further, as in the case of the electrode 81, when forming the first contact 91a and the second contact 91b at the same time in the same process as the first metal bonding film 51, the above-mentioned first metal bonding film may be used as the material for each of these contacts. The same material as the film 51 may be used.

According to the infrared sensor 1 of this embodiment, as described above, the second metal bonding film 52 is separated from the cold junction 42 provided on the first substrate 2 on the lower surface 3a side of the second substrate 3, while By having the infrared ray blocking portion 52A extending to a position facing at least a portion of the cold junction 42, it is possible to suppress infrared rays incident on the infrared sensor 1 from the outside from reaching the cold junction 42. As a result, it is possible to suppress the temperature of the cold junction 42 from rising, so it is possible to maintain the temperature difference between the hot junction 43 and the cold junction 42 when infrared rays are incident, and it is possible to prevent the output signal from the infrared sensor 1 from decreasing. Therefore, it is possible to increase sensor sensitivity.

Further, the infrared ray blocking portion 52A provided on the lower surface 3a side of the second substrate 3 is formed by extending the second metal bonding film 52, and is simultaneously formed with the second metal bonding film 52. Since integral formation is possible, there is no need to provide a new member for blocking infrared rays, and there is no need to add a new process, resulting in excellent productivity. Thereby, an infrared ray blocking structure can be realized with a simple and inexpensive configuration without complicating the manufacturing process. Further, since it is not necessary to add new members, the quality of the infrared sensor 1 does not deteriorate or the manufacturing management becomes difficult, and the yield is improved.

In addition, when the infrared ray blocking section 52A formed by extending the second metal bonding film 52 is configured to extend to a position facing the cold junction 42 so as to cover the entire cold junction 42, the infrared ray sensor 1 can be connected to the infrared sensor 1 from the outside. It is possible to more effectively suppress incident infrared rays from reaching the cold junction 42.

Further, since the position corresponding to the infrared ray blocking portion 52A on the second substrate 3 is set as the separation region 34 provided so as to be dug from the lower surface 3a side of the second substrate 3, the second substrate 3 and the infrared ray blocking portion 52A The portion 52A can be reliably separated from the cold contact 42 without interfering with it. Thereby, it is possible to reliably suppress infrared rays incident from the outside from reaching the cold junction 42, while effectively suppressing an increase in the temperature of the cold junction 42 and its vicinity. Moreover, since no stress is applied due to the film formation of the additional member, damage to the thermopile element 4 can be avoided.

In addition, since the separation area 34 provided on the second substrate 3 has a step shape provided between the lower surface 3a of the second substrate 3 and the cavity portion 32, the second substrate 3 and the infrared shielding portion 52A However, they can be separated more reliably without interfering with the cold junction 42. Thereby, it is possible to more reliably suppress infrared rays incident from the outside from reaching the cold junction 42, and more effectively suppress the rise in temperature of the cold junction 42 and its vicinity.

Further, in the case where the spaced apart area provided on the second substrate 3 is configured to have a slope shape that is gradually inclined between the lower surface 3a of the second substrate 3 and the cavity portion 32, the second substrate 3 The infrared shielding section 52A can be reliably separated from the cold junction 42 without interfering with it. Thereby, it is possible to reliably suppress infrared rays incident from the outside from reaching the cold junction 42, while effectively suppressing an increase in the temperature of the cold junction 42 and its vicinity. Furthermore, compared to the case where the separation region 34 is a step, when forming the infrared ray blocking portion 52A using a method such as sputtering or vapor deposition, no shadow is caused by the step, so that more uniform infrared rays can be obtained. A blocking portion 52A can be formed.

Furthermore, when the spaced apart region provided on the second substrate 3 has the slope shape as described above, by using a silicon substrate with excellent workability as the second substrate 3, the precision when processing by wet etching is improved. Further, by employing a silicon substrate whose plane orientation is (100), which is generally available, it is easy to obtain and can suppress manufacturing costs.
In addition, the slope-shaped separation area provided on the second substrate 3 is an inclined surface formed by the (111) plane of the silicon substrate that appears by performing silicon anisotropic etching on the (100) plane of the silicon substrate by wet etching. When formed, the slope angle of this slope is an angle derived from the crystal anisotropy of the silicon substrate, that is, an slope of about 54.7°, so that the slope has a stable angle. Become. As a result, the second substrate 3 and the infrared ray blocking section 52A can be separated more reliably without interfering with the cold junction 42, thereby reliably suppressing infrared rays incident from the outside from reaching the cold junction 42. At the same time, it is possible to more effectively suppress an increase in the temperature of the cold junction 42 and its vicinity.

Next, an example of processing related to various detections using the infrared sensor 1 of this embodiment will be described.
First, when infrared rays enter from the upper surface 3b side of the second substrate 3 and pass through the second substrate 3, the thermopile element 4 detects the far infrared rays and outputs a detection signal. The detection signal output from the thermopile element 4 passes through the first signal wiring section 61, the second contact 91b, the embedded wiring 71, and the first contact 91a, and is output from the electrode 81 to the outside. The detection signal output from the electrode 81 is transmitted to an external device (not shown) or the like, and a predetermined operation is performed.

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

The method for manufacturing the infrared sensor 1 of this embodiment is, for example, a method for manufacturing the infrared sensor 1 of this embodiment as shown in FIGS. 1 and 2. This method includes at least the following steps (1) to (8) for manufacturing an infrared sensor package.
Step (1): The first substrate 2 is obtained by forming the thermocouple 41 and the membrane thin film 4a and arranging the thermopile type infrared detecting element 4 at the position where the device region 22 is planned to be formed on one side of the substrate material. In this embodiment, in step (1), after forming the membrane thin film 4a so as to cover the planned formation position of the device region 22 on the first substrate 2, at least a part of the thermocouple 41 is disposed on the membrane thin film 4a. The cold junction 42, which is a part of the thermocouple 41, is arranged outside the opening 22a of the device region 22, and the hot junction 43, which is a part of the thermocouple 41, is placed on the membrane thin film 4a. By arranging the thermopile element 4, the first substrate 2 is obtained.
Step (2): By etching the surface of the substrate material, a penetration region 33 is formed in at least a portion of the silicon substrate, and a concave cavity portion 32 is formed on the lower surface 3a side that will be the bonding surface with the first substrate 2. The second substrate 3 is obtained by forming a bonding portion 31 that surrounds the cavity portion 32 in a plan view.
Step (3): A first metal bonding film 51 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.
Step (4): The electrode 81 is arranged in the electrode arrangement region 23a on the upper surface 2a side of the first substrate 2 obtained in step (1).
Step (5): Form a concave device region 22 on the upper surface 2a side of the first substrate 2 by etching the surface of the first substrate 2 obtained in step (1) at the planned formation position of the device region 22. .
Step (6): A second metal bonding film 52 is formed to cover the bottom surface 31a of the bonding portion 31 of the second substrate 3 obtained in step (2), which is the position to be bonded to the first substrate 2. Further, in the present embodiment, in step (6), the second metal bonding film 52 is separated from the cold contact 42 provided on the first substrate 2 on the lower surface 3a side of the second substrate 3, and the cold contact is Step (7): The thermopile element 4 is arranged between the first substrate 2 and the second substrate 3. A cavity C is secured above the thermopile element 4 by overlapping the first substrate 2 and the second substrate 3 and pressurizing the first metal bonding film 51 and the second metal bonding film 52 to perform metal diffusion bonding. At the same time, the first substrate 2 and the second substrate 3 are bonded.
Step (8): The first substrate 2 and the second substrate 3 are cut along the dicing line L to separate them into chips.

Further, in the present embodiment, an example will be described in which the above step (2) forms the separation region 34 as a stepped shape provided between the lower surface 3a of the second substrate 3 and the cavity portion 32.
Further, in the present embodiment, the above step (6) is performed by connecting the infrared ray blocking portion 52A of the second metal bonding film 52 to the cold contact 42 provided on the first substrate 2 on the lower surface 3a side of the second substrate 3. An example will be described in which the cold junction is formed by extending to a position facing the entire cold junction 42 while being separated from the cold junction.

First, in step (1), the thermopile type infrared detecting element 4 is arranged by forming a thermocouple 41 and a membrane thin film 4a at the planned formation position of the device region 22 on the surface of a substrate material made of, for example, a silicon substrate. Obtain a first substrate 2 (see first substrate 2 in FIG. 3F).
Specifically, in step (1), first, the membrane thin film 4a is formed so as to cover the planned formation position of the device region 22 on the first substrate 2. At this time, as the material of the membrane thin film 4a, for example, a silicon oxide film such as silicon dioxide (SiO ₂ ), a silicon nitride film (SiN _x ), or a thin film made of a laminated film thereof is used. By adhering to the upper surface 2a, the planned formation position of the device region 22 is covered.

Next, the thermocouple 41 is formed so as to be placed over both the membrane thin film 4a and the upper surface 2a of the first substrate 2. At this time, as in the example shown in FIG. 1, a first thermocouple 41a and a second thermocouple 41b each made of different metals are used, and the first thermocouple 41a and second thermocouple 41b are alternately arranged in a comb-like shape. It is placed on the membrane thin film 4a so as to be connected to the membrane thin film 4a. More specifically, for example, p-type polysilicon is used as the material for the first thermocouple 41a, and n-type polysilicon is used as the material for the second thermocouple 41b. 41a and the second thermocouple 41b are formed using a method such as a sputtering method or a vapor deposition method (CVD method).

In step (1), as shown in FIG. 1, the contact between the first thermocouple 41a and the second thermocouple 41b is formed as a cold junction 42 or a hot junction 43. At this time, the cold junction 42 is arranged outside the opening 22a of the device region 22 on the upper surface 2a of the first substrate 2, and the hot junction 43 is arranged on the membrane thin film 4a.

Next, as shown in FIG. 2, an infrared absorbing film 4b is formed on the membrane thin film 4a so as to cover the membrane thin film 4a and the thermocouple 41a provided thereon. Thereby, the infrared absorbing film 4b is formed so as to also cover the hot junction 43. In the manufacturing method of this embodiment, the infrared absorbing film 4b can be formed using, for example, a black gold film, a resin material, or the like as a material, and using a method such as a vapor deposition method or a screen printing method.

Next, in the example described in this embodiment, in the above step (1), embedded wiring 71 is formed in the first substrate 2 at a position excluding the device region 22 (see first substrate 2 in FIG. 3F). .

Specifically, first, an insulating film (oxide film) (not shown) is formed on the upper surface 2a of the first substrate 2.
Next, a layered structure of {TiN/AlSi/TiN} or a buried wiring film made of polysilicon is formed in the region where the above-mentioned insulating film (not shown) is formed by, for example, sputtering method or vapor deposition method (CVD method). The film is formed using a method such as
Next, a resist pattern made of an oxide film (not shown), etc., for forming the buried wiring 71 is formed by photolithography.
Next, a patterned buried wiring 71 is formed by dry etching the buried wiring film.
Next, the resist pattern is peeled off from the first substrate 2.

Next, an insulating film (not shown) (such as an oxide film or a nitride film) is formed on the buried wiring 71 by, for example, a vapor deposition method to cover the buried wiring 71.
Thereafter, if necessary, the insulating film (not shown) formed on the buried wiring 71 is planarized by, for example, a CMP method (Chemical Mechanical Polishing).

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

In the present embodiment, the above step (1) is carried out, and in step (2), a through region 33 is formed in at least a part of the silicon substrate by etching the substrate material made of, for example, a silicon substrate. The second substrate 3 is manufactured by forming a concave cavity portion 32 on the lower surface 3a side that will be the bonding surface with the first substrate 2, and further forming a bonding portion 31 provided so as to surround the cavity portion 32 in plan view. Implement processes to Further, in the example described in this embodiment, in step (2), a step-shaped separation region 34 is formed between the lower surface 3a of the second substrate 3 and the cavity portion 32 (as shown in FIG. 3A, (See Figures 3B and 3C).

That is, in step (2), first, a silicon substrate serving as a substrate material is prepared (see FIG. 3A).
Next, a resist consisting of an oxide film (not shown) is formed on the surface of the silicon substrate by dry etching to form the cavity portion 32, the penetration region 33, the bonding portion 31, and the step-shaped separation region 34 by photolithography. form a pattern.

Next, by dry etching one surface side (upper surface 3b side) of the silicon substrate, as shown in FIG. 3B, first, the silicon substrate is divided into rectangular shapes while forming penetration regions 33.
In addition, in step (2), as shown in FIG. 3D, the silicon substrate is etched to form a penetration region 33, and a concave cavity portion 32 is formed on the lower surface 3a side so as to surround the cavity portion 32 in plan view. The second substrate 3 is obtained by forming a generally frame-shaped joint portion 31 provided in the wafer and a step-shaped spaced apart region 34 .

The dimensions and planar view shape of the penetration region 33 formed in step (2) are not particularly limited, and may be any shape or dimension as long as it exposes the electrode 81 and is easily connected to the outside. It's okay.

Next, in step (2), as shown in FIG. 3C, the silicon substrate is etched from the other surface side (lower surface 3a side) by dry etching to form the surface of the step-shaped separation region 34 shown in FIG. form a recess.

Next, as shown in FIG. 3D, by selectively etching the periphery of the recess shown in FIG. 3C by dry etching, the joint 31 is formed in a surrounding shape in plan view so as to surround the recess.
Next, as shown in FIG. 3D, a cavity portion 32 is formed by selectively etching approximately the center of the concave portion shown in FIG. form. As a result, the concave cavity portion 32 is arranged so as to be surrounded by the spaced apart region 34 and the joint portion 31 which have an encircling shape in plan view. In the infrared sensor 1 obtained by the manufacturing method of this embodiment, a region corresponding to the cavity portion 32 is secured as a cavity C, which is a sealed space.
Thereafter, the resist pattern (not shown) is peeled off from the second substrate 3.

In step (2), similarly to step (1), when forming a resist pattern by photolithography, the resist pattern can be formed under conventionally known conditions using, for example, a spin coating method.
Also in step (2), while the silicon substrate can be etched using dry etching, a method using wet etching can also be adopted. In this way, when wet etching is adopted in step (2), the same etching solution as in step (1) is used, and the conditions such as the temperature of the etching solution and etching time are also the same. I can do it.

Next, in step (3), a plurality of metal films are formed on the upper surface 2a side of the first substrate 2 obtained in step (1) at a position corresponding to the joint portion 31 provided on the second substrate 3. A first metal bonding film 51 is formed (see FIG. 3F).
In addition, in the example described in this embodiment, by performing step (3) and step (4) simultaneously, the electrode arrangement region 23a is applied to the upper surface 2a of the first substrate 2 together with the first metal bonding film 51. It is also possible to form the electrode 81 on the surface. Further, in this embodiment, in the step (3) and step (4) that are performed simultaneously, in addition to the first metal bonding film 51 and the plurality of electrodes 81, the first contact 91a, the second contact 91b, and the It is also possible to form the 1-signal wiring section 61 at the same time.

Specifically, first, an oxide film (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 a spray coating method to form the first metal bonding film 51. A resist pattern consisting of the following is formed. At this time, a position on the upper surface 2a of the first substrate 2 corresponding to the joint part 31 of the second substrate 3, a position of a hole for forming the first contact 91a, the first signal wiring part 61, and the second contact 91b, Additionally, a resist pattern is formed on the entire surface except for the position where the electrode 81 is to be formed.

Next, a first metal bonding film 51 in which a first base layer 51a and a first bonding layer 51b are laminated on the upper surface 2a of the first substrate 2 by a method such as sputtering, vapor deposition, or plating is then formed. form.
In step (3), the first metal bonding film 51 made of a thin film having the above-mentioned {Au/Ta} structure or {Al/TiN} structure can be formed by appropriately selecting the material and the lamination order. can be formed.
Furthermore, at this time, if the second metal bonding film 52 formed on the second substrate 3 side has a {Au/Ta} structure, the first metal bonding film 51 is also formed from the same material. In this case, the stacking order of each layer is adjusted so that the Au layer of the first metal bonding film 51 (first bonding layer 51b) and the Au layer of the second metal bonding film 52 (second bonding layer 52b) are bonded. adjust.
Similarly, when the second metal bonding film 52 has a {Al/TiN} structure, the first metal bonding film 51 is also formed from the same material. In this case, the stacking order of each layer is adjusted so that the Al layer of the first metal bonding film 51 (first bonding layer 51b) and the Al layer of the second metal bonding film 52 (second bonding layer 52b) are bonded. adjust.
Thereafter, the resist pattern (not shown) is peeled off from the upper surface 2a of the first substrate 2.

Further, in step (3) of the example described in this embodiment, as shown in FIG. 3F, a conductive material is deposited on the upper surface 2a side of the first substrate 2 by a method such as a sputtering method, a vapor deposition method, or a plating method. By stacking, the first contact 91a and the second contact 91b are formed so as to be connected to both ends of the buried wiring 71, respectively.
Furthermore, in step (4), electrodes 81 are formed so as to be respectively connected to the first contacts 91a, and first signal wiring parts 61 are formed so as to be respectively connected to the second contacts 91b. .

At this time, the first contact 91a and the second contact 91b are formed using, for example, tungsten (W) by a method such as a sputtering method or a vapor deposition method so as to be embedded in the hole formed in the above step (2). can do. Further, the electrodes 81 can be formed by sequentially stacking TiN and AlSi at the positions where the electrodes 81 are to be formed (electrode arrangement region 23a) by a method such as sputtering. Furthermore, the first signal wiring section 61 can also be formed by sequentially laminating TiN and AlSi at the intended formation positions using a method such as sputtering.

On the other hand, for example, when forming the first contact 91a, the second contact 91b, the electrode 81, and the first signal wiring part 61 at the same time in the same process as the first metal bonding film 51, the first metal bonding film described above It can be formed using the same material as 51, for example, by sputtering, vapor deposition, or plating. In this case, the first contact 91a, the second contact 91b, the electrode 81, and the first signal wiring section 61 have the same laminated structure as the first metal bonding film 51, that is, the {Au/Ta} structure, or the {Al /TiN} structure.

Next, in this embodiment, the above-described steps (3), (4), and (5) are carried out, and in parallel with these, in step (6), the second substrate 3 as described above is A process is performed to form a second metal bonding film 52 so as to cover the bottom surface 31a, which is the position to be bonded to the first substrate 2, in the bonding portion 31 (see FIG. 3C). Further, in the present embodiment, in step (6), the infrared ray blocking portion 52A of the second metal bonding film 52 is separated from the cold contact 42 provided on the first substrate 2 on the lower surface 3a side of the second substrate 3. However, it is formed so as to extend to a position facing the entire cold junction 42. Further, in this embodiment, as in the example shown in FIGS. 3F and 3G, the infrared ray blocking section 52A is extended to cover the step-shaped separation region 34.

Specifically, first, the second metal bonding film 52 including the infrared blocking portion 52A is formed on the lower surface 3a side of the second substrate 3 obtained in step (2) by a photolithography method such as a spray coating method. A resist pattern (not shown) is formed for this purpose. At this time, a resist pattern is formed on the entire surface of the second substrate 3 on the lower surface 3a side except for the bottom surface 31a of the joint portion 31.

Next, as shown in FIG. 3C, a second base layer 52a and a second bonding layer 52b are laminated on the bottom surface 31a of the bonding portion 31 by a method such as sputtering, vapor deposition, or plating. A two-metal bonding film 52 is formed. At this time, the second metal bonding film 52 is further extended to cover the step-shaped separation region 34, thereby forming the infrared ray blocking portion 52A at the same time.
At this time, by appropriately selecting the material and the lamination order, the second metal bonding film 52 including the infrared ray blocking portion 52A, which is made of a thin film having the above-mentioned {Au/Ta} structure or {Al/TiN} structure, can be formed. can be formed.
Thereafter, the resist pattern (not shown) is peeled off from the lower surface 3a of the second substrate 3.

In addition, in the above steps (3) and (6), for the purpose of Au-Sn eutectic bonding between the first metal bonding film 51 and the second metal bonding film 52 in the below-described step (7), For example, 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).

Next, in step (5), wet etching is performed on the surface of the first substrate 2 obtained in step (1) at the planned formation position of the device region 22 to form a concave device region disposed below the thermopile element 4. 22 (see first substrate 2 in FIG. 3F).
Specifically, in step (5), first, a process is performed to form a concave device region 22 by wet etching, for example, by photolithography, at a position where the device region 22 is planned to be formed on the upper surface 2a of the first substrate 2. , a resist pattern (not shown) is formed.
Next, a recessed device region 22 is formed by wet etching the surface of the silicon substrate.
After that, the resist pattern is peeled off from the first substrate 2.

In step (5), when forming a resist pattern by photolithography, the resist pattern can be formed under conventionally known conditions using, for example, a spin coating method.
Furthermore, the conditions for wet etching in step (5) are not particularly limited, and include, for example, hydrazine (N ₂ H ₄ ), potassium hydroxide, etc. Etching solutions such as (KOH) and tetramethylammonium hydroxide (TMAH) can be used. Further, regarding various conditions such as the temperature of the etching solution and the etching time, conventionally known conditions can be employed without any restrictions.
Further, in step (5), while the silicon substrate can be etched using wet etching, a method using dry etching can also be adopted.

Next, in step (7), as described above, the first substrate 2 and the second substrate 3 are stacked so that the thermopile element 4 is placed between the first substrate 2 and the second substrate 3. By pressurizing the first metal bonding film 51 and the second metal bonding film 52 to perform metal diffusion bonding, the first substrate 2 and the second substrate 3 are bonded while securing the cavity C on the thermopile element 4. Join (see Figure 3G). At this time, due to the step-shaped separation area 34 provided on the second substrate 3, the infrared ray blocking portion 52A formed on this surface does not buffer the cold junction 42 provided on the first substrate 2 side. The first substrate 2 and the second substrate 3 are bonded.

Specifically, first, as shown in FIG. 3G, the first substrate 2 and the second substrate 3 are stacked so that the first metal bonding film 51 and the second metal bonding film 52 are butted against each other.
Next, by pressurizing the first substrate 2 and the second substrate 3 against each other, metal diffusion bonding is developed between the first metal bonding film 51 and the second metal bonding film 52, and these parts are bonded. Then, a metal bonded body 50 is formed. At this time, since the infrared ray blocking portion 52A formed by extending the second metal bonding film 52 is formed in the step-shaped separation region 34, the first metal bonding film 52A provided on the first substrate 2 side There is no contact with

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

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

As described above, when the first substrate 2 and the second substrate 3 are bonded, the sealing width (joining width) of the cavity C by the metal bonding body 50, that is, the metal formed corresponding to the bonding portion 31. The maximum width of the joined body 50 is also not particularly limited. On the other hand, in consideration of improving the bondability of this part and further increasing the sealing airtightness of the cavity C, the above sealing width (maximum width) is When the first bonding layer 51b and the second bonding layer 52b are made of Au, the thickness is preferably 0.10 to 0.30 mm, for example. Further, 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 may be, for example, 0.03 to 0.1 mm. preferable.

Further, in step (7), as described above, each layer of the first metal bonding film 51 and the second metal bonding film 52 is made of gold (Au) or tin (Sn), so that Au-Sn eutectic The metal joined body 50 may be formed by joining. In this case, for example, it is preferable that the temperature conditions be in the range of 300 to 400° C., the pressure to be in the range of 0 to 1 kPa, and the sealing width to be in the range of 0.1 to 0.5 mm.

In the present embodiment, in step (8), the first substrate 2 is cut into individual chips by blade dicing or the like along the dicing line L shown in FIG. 3G.
Through each of the above steps, an infrared sensor 1 including the infrared sensor package of this embodiment as shown in FIGS. 1 and 2 can be manufactured.
Note that each of the above steps can be performed in the same order or in a different order to the extent possible.

According to the manufacturing method of the infrared sensor 1 of the present embodiment, first, the above step (6) is performed by providing the second metal bonding film 52 on the first substrate 2 on the lower surface 3a side of the second substrate 3. The infrared rays incident from the outside can reach the cold junction 42 by forming the infrared ray blocking part 52A that extends to a position facing at least a part of the cold junction 42 while being separated from the cold junction 42. It is possible to manufacture an infrared sensor 1 having a structure that can suppress the above.
Furthermore, by forming the infrared shielding part 52A provided on the lower surface 3a side of the second substrate 3 by extending the second metal bonding film 52, it is possible to form it simultaneously and integrally with the second metal bonding film 52. , there is no need to provide a new member for blocking infrared rays, there is no need to add a new process, and excellent productivity can be obtained.
This makes it possible to manufacture the infrared sensor 1 with high productivity and low cost, which has excellent sensor sensitivity and excellent yield.

In addition, in step (6), the infrared ray blocking portion 52A on the lower surface 3a side of the second substrate 3 is separated from the cold contact 42 provided on the upper surface 3a of the first substrate 2, while covering the entire cold contact 42. When extended to opposing positions, it is possible to manufacture an infrared sensor 1 having a structure that can effectively suppress infrared rays incident from the outside from reaching the cold junction 42.

Further, in step (2), by adopting a method of forming a position corresponding to the infrared ray blocking portion 52A on the second substrate 3 as a spaced region 34 dug from the lower surface 3a side, the second substrate 3 and the The infrared shielding portion 52A formed by extending the two-metal bonding film 52 can be reliably separated from the cold contact 42 without interfering with it.

Further, in step (2), by adopting a method of forming the separation region 34 as a stepped shape provided between the lower surface 3a of the second substrate 3 and the cavity portion 32, as described above, the second substrate 3 and the infrared ray blocking portion 52A formed by extending the second metal bonding film 52 can be separated more reliably without interfering with the cold contact 42.

Note that in the manufacturing method of the present embodiment, step (2) may be a method in which the separation region 34 is formed as a slope shape that gradually slopes between the lower surface 3a of the second substrate 3 and the cavity portion 32. good. That is, in the manufacturing method of this embodiment, step (2) uses a silicon substrate as the material of the second substrate 3, and the infrared shielding part 52A of the second metal bonding film 52 is connected to the cold contact 42 on the first substrate 2. The position corresponding to the infrared ray blocking portion 52A on the second substrate 3 can be formed as a slope shape that gradually slopes between the lower surface 3a of the second substrate 3 and the cavity C so as to be spaced apart from each other. Further, in the manufacturing method of the present embodiment, step (2) includes performing silicon anisotropic etching on the (100) plane of the silicon substrate by wet etching to form the slope-shaped separation region 34 on the second substrate 3. It is possible to adopt a method of forming an inclined surface consisting of the (111) plane of the silicon substrate, which appears in , and the inclination angle of this inclined surface is an angle derived from the crystal anisotropy of the silicon substrate.

In step (2), first, by using a silicon substrate with excellent workability as the material of the second substrate 3, the accuracy when processing by wet etching is improved. Further, by employing a silicon substrate whose plane orientation is (100), which is generally available, it is easy to obtain and it is possible to suppress manufacturing costs.
In addition, in step (2), the infrared ray blocking portion 52A of the second metal bonding film 52 corresponds to the infrared ray blocking portion 52A on the second substrate 3 so that it is spaced apart from the cold contact 42 on the first substrate 2. By forming the position as a slope shape that gradually slopes between the lower surface 3a of the second substrate 3 and the cavity portion 32, the infrared ray blocking portion 52A is formed by extending the second substrate 3 and the second metal bonding film 52. can be separated more reliably without interfering with the cold junction 42.
In addition, in step (2), the slope-shaped separation region 34 formed on the second substrate 3 is formed by etching the (100) plane of the silicon substrate by wet etching. ) plane, and the inclination angle of this inclined plane is an angle derived from the crystal anisotropy of the silicon substrate, that is, an inclination of about 54.7°, the slope shape has a stable angle. A spaced apart region 34 can be formed. Thereby, the separation region 34 can be formed such that the second substrate 3 and the infrared ray blocking section 52A are further reliably separated from each other without interfering with the cold contact 42.

Further, in the manufacturing method of this embodiment, step (6) may adopt a method in which the entire second metal bonding film 52 including the infrared shielding portion 52A is integrally formed in the same step.
In this way, in step (6), by forming the entire second metal bonding film 52 including the infrared shielding portion 52A in the same step, the time required for step (6) can be reduced, so productivity can be further increased. , it becomes possible to manufacture the infrared sensor 1 at lower cost.

Further, in the manufacturing method of the present embodiment, step (6) includes at least the infrared ray blocking portion 52A of the second metal bonding film 52 in the spaced region 34 formed on the second substrate 3 in step (2). You may adopt the method of forming simultaneously.
In this manner, by forming at least the infrared ray blocking portion 52A of the second metal bonding film 52 at the same time as the separation region 34 formed on the second substrate 3, the time required for each process can be reduced. This further increases productivity and allows the infrared sensor 1 to be manufactured at even lower cost.

<Second embodiment>
Below, an infrared sensor according to a second embodiment of the present disclosure and a method for manufacturing the same will be described in detail with reference to FIG. 4 as appropriate.
FIG. 4 is a cross-sectional view schematically explaining the infrared sensor 100 of this embodiment.
In addition, in the infrared sensor 100 of the second embodiment described below, the same components as those of the infrared sensor 1 of the first embodiment described above are given the same reference numerals in the drawings, and detailed explanations thereof will be omitted. May be omitted.

As shown in FIG. 4, the infrared sensor 100 of the second embodiment is different from the first embodiment in that it has an infrared blocking section 52A extending from the second metal bonding film 52 provided on the second substrate 3A side. It is similar to the infrared sensor 1 of the form.
On the other hand, in the infrared sensor 100 of this embodiment, the cavity portion 32A provided on the lower surface 3a side of the second substrate 3A extends outward of the second substrate 3A in plan view as it goes from the upper surface 3b side to the lower surface 3a side. The infrared sensor 1 is different from the infrared sensor 1 of the first embodiment described above in that the infrared sensor 1 has an inclined surface that is inclined toward the opposite direction. That is, in this embodiment, the inner surface 32b of the cavity portion 32A in the second substrate 3A is not an upright surface but an inclined surface. More specifically, in the infrared sensor 100 of the second embodiment, the inner surface 32b of the cavity portion 32A in the second substrate 3A is formed by etching silicon anisotropically on the (100) plane of the silicon substrate by wet etching. The inclined surface is formed of the (111) plane of the silicon substrate, and is inclined toward the outer side of the second substrate 3A in plan view as it goes from the ceiling surface 32a of the cavity portion 32A toward the lower surface 3a side. This is different from the infrared sensor 1 of the first embodiment in that the infrared sensor 1 is different from the infrared sensor 1 of the first embodiment.

As shown in FIG. 4, in the infrared sensor 100 of the second embodiment as well, the second metal bonding film 52 provided on the second substrate 3A is similar to the infrared sensor 1 of the first embodiment. On the lower surface 3a side of the substrate 3, an infrared ray blocking portion 52A is provided that extends to a position facing the cold contact 42 provided on the upper surface 2a of the first substrate 2 while being separated from the cold contact 42. As a result, similar to the infrared sensor 1 of the first embodiment, excellent sensor sensitivity can be obtained with a simple and inexpensive configuration without adding new members or new manufacturing processes.

Furthermore, according to the infrared sensor 100 of the present embodiment, the inner surface 32b of the cavity portion 32A in the second substrate 3A is an inclined surface, which has the effect of suppressing attenuation of infrared rays incident from an oblique direction, for example. You can expect it. As a result, the incident range of light can be made wider, so that the effect of efficiently receiving infrared rays at a wider detection angle can be stably obtained.

Further, in the infrared sensor 100, the inner surface 32b of the cavity portion 32A is made of the (111) plane of the silicon substrate, and has an inclination of about 54.7°, which is a crystal angle derived from the crystal anisotropy of the silicon substrate. It may have. As a result, the inner surface 32b of the cavity portion 32A becomes an inclined surface with a stable angle, and the effect of further widening the light incident range can be expected. The effect of receiving light can be achieved more stably.

When manufacturing the infrared sensor 100 of this embodiment, in step (2), the silicon substrate is wet-etched so that the silicon substrate is wet-etched so that the silicon substrate is wet-etched so as to be etched from the upper surface 3b side to the lower surface 3a side of the second substrate 3A. A method can be adopted in which the cavity portion 32A is provided by forming an inner side surface 32b that is inclined toward the outer side of the second substrate 3A in a plan view.
That is, in this embodiment, the inner surface 32b of the cavity portion 32A is formed as an inclined surface where the (111) plane of the silicon substrate appears by anisotropically etching the (100) plane of the silicon substrate using wet etching. You can adopt the method of forming. Thereby, the cavity portion 32A can be formed so as to be inclined toward the outside of the second substrate 3A in plan view as it goes from the ceiling surface 32a toward the lower surface 3a.
Furthermore, in the present embodiment, in step (2), the (100) plane of the silicon substrate on the inner surface 32b of the cavity portion 32A is anisotropically etched by wet etching, thereby etching the (111) plane of the silicon substrate. By causing the (111) plane to appear, a method can be adopted in which the inclination angle of the (111) plane is approximately 54.7°, which is an angle derived from the crystal anisotropy of the silicon substrate.

To explain step (2) of this embodiment in more detail, first, a silicon substrate having a (100) plane is adopted as the second substrate 3A, and when this silicon substrate is etched, the crystal anisotropy of silicon A gradient in etching rate occurs due to Due to this action, the inner surface 32b of the cavity portion 32A is obtained, which has an inclined surface shape as shown in the illustrated example, and in which a (111) plane appears. The second substrate 3A obtained by such a procedure has a cavity portion 32A with improved shape accuracy.

In this embodiment, the etching conditions for obtaining the second substrate 3A by wet etching the silicon substrate are not particularly limited, and the etching conditions described in the first embodiment can be adopted without any restrictions. It is.
Further, in the step (2), when the cavity portion 32A is formed by wet etching and the joint portion 31 and the penetration region 33 are also formed by wet etching, the second substrate 3A can be obtained by batch processing in the same process. This makes it possible to improve production efficiency and reduce manufacturing costs.

<Third embodiment>
Below, an infrared sensor package and an infrared sensor according to a third embodiment of the present disclosure, and a method for manufacturing the same will be described in detail with reference to FIGS. 5 and 6 as appropriate.
FIG. 5 is a plan view schematically explaining the infrared sensor 110 of this embodiment, and FIG. 6 is a BB cross-sectional view of the infrared sensor 110 shown in FIG.
In addition, in the infrared sensor 110 of the third embodiment described below, the same reference numerals are given to the same components in the figures as in the infrared sensors 1, 100 of the first and second embodiments described above. The detailed explanation may be omitted.

As shown in FIGS. 5 and 6, the infrared sensor 110 of the third embodiment has an electrode arrangement arranged in penetration regions 33, 33 provided on the second substrate 3B and on the upper surface 2a of the first substrate 2A. The electrodes 81 and 82 provided in the regions 23a and 23b are provided on both one side and the other side facing each other in a plan view of the first substrate 2A and the second substrate 3B. This is different from the infrared sensor 1,100 of the embodiment.

In the example shown in FIG. 5, electrodes 81 are arranged at two locations at equal intervals in one electrode arrangement region 23a of the first substrate 2A, and electrodes 82 are arranged at four locations in the other electrode arrangement region 23b. They are placed at equal intervals.

Further, as shown in FIG. 6, the infrared sensor 110 of this embodiment has the first, This is different from the infrared sensor 1,100 of the second embodiment.
Furthermore, the infrared sensor 110 of this embodiment is also characterized in that the electrodes 81, 82 and one end side of the embedded wirings 71, 72 are electrically connected by the first contact 91a or the first contact 92a, respectively. , is different from the infrared sensor 1,100 of the first and second embodiments.
Furthermore, the infrared sensor 110 of this embodiment connects the first signal wiring section 61 or the second signal wiring section 62 to the other end side of the embedded wirings 71 and 72 via the second contact 91b or the second contact 92b, respectively. It also differs from the infrared sensor 1,100 of the first and second embodiments in that the infrared sensor 1,100 is connected.

As in the illustrated example, when the first substrate 2A and the second substrate 3B are configured to have a rectangular shape in plan view, at least Although it is sufficient that the electrode placement area is provided along one side, it is also possible to arrange the electrodes 81 and 82 (electrode placement areas 23a and 23b) on both sides that face each other in plan view, as in this embodiment. be. Therefore, the positions and numbers of the electrodes provided on the first substrate 2A and the penetration areas provided on the second substrate 3B are determined by, for example, the space required for COBing an infrared sensor package to a printed circuit board, etc. This makes it possible to design flexibly while assuming application to a chip on which a signal amplification circuit, a signal input/output control circuit, etc. are mixed.

When the electrode arrangement area 23a (electrode 81) is provided only on one side of the first substrate 2 as in the infrared sensor 1,100 of the first and second embodiments described above, the print on which the infrared sensor is mounted It becomes possible to downsize the substrate. On the other hand, as in the infrared sensor 110 of the third embodiment, when the electrode arrangement area 23b (electrode 82) is further provided on the other side of the first substrate 2A, more complicated electrical connections can be accommodated. It is also possible to do so.

Further, as shown in FIG. 6, in the infrared sensor 110 of this embodiment, the second metal bonding film 52 provided on the second substrate 3B is similar to the infrared sensors 1, 100 of the first and second embodiments. However, on the lower surface 3a side of the second substrate 3, there is an infrared ray blocking portion 52A that extends to a position facing the cold contact 42 provided on the upper surface 2a of the first substrate 2A while being separated from the cold contact 42. ing. As a result, similar to the infrared sensors 1 and 100 of the first and second embodiments, excellent sensor sensitivity can be obtained with a simple and inexpensive configuration without adding new members or new manufacturing processes.

As described above, the infrared sensor of the present disclosure can suppress the temperature rise of the cold junction by avoiding infrared rays from entering the cold junction with a simple configuration and manufacturing process without adding any new members. , excellent sensor sensitivity and sensor quality can be obtained, as well as low cost and excellent yield and productivity. Therefore, the infrared sensor of the present disclosure is very useful in applications such as small electronic devices that require highly reliable infrared detection accuracy, such as mobile terminals, smartphones, sensor network devices, Internet of Things (IoT) technology, etc. suitable.

1, 100, 110... Infrared sensor 2, 2A... First substrate 2a... Top surface 2b... Bottom surface 22... Device area 22a... Opening 23a, 23b... Electrode placement area 3, 3A, 3B... Second substrate 3a... Bottom surface 3b... Top surface 31... Joint portion 31a... Bottom surface 32, 32A... Cavity portion 32a... Ceiling surface 33... Penetration region 4... Thermopile type infrared detection element (thermopile element)
4a... Membrane thin film 4b... Infrared absorbing film 41... Thermocouple 41a... First thermocouple 41b... Second thermocouple 42... Cold junction 43... Hot junction 50... Metal bonded body 51... First metal bonding film 51a... First bottom Geological layer 51b...First bonding layer 52...Second metal bonding film 52a...Second base layer 52b...Second bonding layer 52A...Infrared blocking section 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 C... Cavity

Claims (11)

A thermopile in which a sealed space is secured by bonding a first metal bonding film provided on the top surface of the first substrate and a second metal bonding film provided on the bottom surface of the second substrate. A type of infrared sensor,
The second metal bonding film extends on the lower surface side of the second substrate to a position facing at least a portion of the cold contacts while being separated from the cold contacts provided on the first substrate. An infrared sensor characterized by having an infrared blocking section. The infrared ray blocking section is provided on the lower surface side of the second substrate, and extends to a position facing the entire cold contact while being separated from the cold contact provided on the first substrate. The infrared sensor according to claim 1. The second substrate includes a separation area provided such that a position corresponding to the infrared ray blocking part is dug from the lower surface side so as to separate the infrared ray blocking part from the cold contact on the first substrate. The infrared sensor according to claim 1 or 2, characterized in that: The second substrate is provided with a concave cavity portion on the lower surface side for forming the sealed space, and the separation region is between the lower surface of the second substrate and the cavity portion. The infrared sensor according to claim 3, wherein the infrared sensor has a stepped shape. 4. The infrared sensor according to claim 3, wherein the separation area has a slope shape that is gradually inclined between the lower surface of the second substrate and the cavity portion. The second substrate is made of a silicon substrate, and the slope-shaped spaced region provided on the second substrate appears by wet etching silicon anisotropically on the (100) plane of the silicon substrate. 6. The slope of the silicon substrate is a (111) plane, and the slope angle of the slope is an angle derived from crystal anisotropy of the silicon substrate. infrared sensor. The first substrate and the second substrate have a rectangular shape in plan view,
In the first substrate, an electrode arrangement region in which an electrode is provided is arranged on the outside in a plan view on the upper surface side,
The infrared ray according to any one of claims 1 to 6, wherein the electrode arrangement region is arranged along at least one side of the first substrate and the second substrate in plan view. sensor. a step (1) of obtaining a first substrate by forming a thermocouple and a membrane thin film and arranging the thermopile-type infrared detection element at a position where a device region is planned to be formed on one side of the substrate material;
By etching the surface of the substrate material, a penetrating region is formed in at least a portion of the substrate material, and a concave cavity portion is formed on the lower surface side that will be the bonding surface with the first substrate, and further, when viewed from the top, a step (2) of forming a joint part provided so as to surround the cavity part to obtain a second substrate;
a step (3) of forming a first metal bonding film on one side of the first substrate obtained in the step (1) at a position corresponding to the bonding portion provided on the second substrate;
a step (4) of arranging an electrode in the electrode arrangement region on one side of the first substrate obtained in the step (1);
a step (5) of forming a concave device region on the one surface side of the first substrate by etching the surface of the first substrate obtained in the step (1) at a position where the device region is planned to be formed; ,
a step (6) of forming a second metal bonding film so as to cover a position to be bonded to the first substrate in the bonding portion of the second substrate obtained in the step (2);
The first substrate and the second substrate are stacked so that the far-infrared detecting element is disposed between the first substrate and the second substrate, and the first metal bonding film and the second metal bonding film are bonded to each other. a step (7) of bonding the first substrate and the second substrate while securing the sealing space above the far-infrared detecting element by pressurizing and bonding the films to each other;
a step (8) of dividing the first substrate into individual chips by cutting the first substrate along dicing lines;
Equipped with
The step (1) includes forming a membrane thin film so as to cover the planned formation position of the device region on the first substrate, and then arranging at least a part of the thermocouple on the membrane thin film. The thermopile type infrared detecting element is arranged so that the cold junction, which is a part of the thermocouple, is located outside the opening of the device region, and the hot junction, which is a part of the thermocouple, is arranged on the membrane thin film. place,
In the step (6), the second metal bonding film is separated from the cold contacts provided on the first substrate on the lower surface side of the second substrate, and faces at least a portion of the cold contacts. 1. A method of manufacturing an infrared sensor, the method comprising: forming an infrared sensor so as to have an infrared blocking portion extending to a position where the infrared sensor is 9. The method of manufacturing an infrared sensor according to claim 8, wherein in the step (6), the entire second metal bonding film including the infrared blocking portion is integrally formed in the same step. The step (6) is characterized in that at least the infrared ray blocking portion of the second metal bonding film is formed at the same time as the separation region formed on the second substrate in the step (2). The method for manufacturing an infrared sensor according to claim 8. In step (2), a silicon substrate is used as the material of the second substrate, and the infrared ray blocking portion of the second metal bonding film is spaced apart from the cold contact on the first substrate. The position corresponding to the infrared ray blocking section on the second substrate is formed as a slope shape that gradually slopes between the lower surface of the second substrate and the cavity section, and the slope-shaped separation area is formed on the silicon substrate. The (100) plane of the silicon substrate is an inclined plane formed by the (111) plane of the silicon substrate that appears by anisotropic etching of silicon by wet etching, and the angle of inclination of the inclined plane is set according to the crystal anisotropy of the silicon substrate. 9. The method of manufacturing an infrared sensor according to claim 8, wherein the angle is formed as an angle derived from directionality.

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