JP2003017672A - Electronic device, manufacturing method thereof, camera and vehicle - Google Patents

Abstract

(57) [Problem] To provide an electronic device equipped with an infrared sensor and a visible light sensor, a camera, a vehicle, a method of manufacturing the same, and the like by utilizing an existing electronic device manufacturing process. SOLUTION: An Al film 1 is formed on a cap wafer 150.
51 is formed, and the Al film 151 is patterned to form an annular film 144. Dry etching is performed using the annular film 144 as a mask, and a cylindrical portion 142 surrounding a concave portion serving as a vacuum dome for an infrared sensor and a cylindrical portion 14 for a visible light sensor.
2a is formed. On the other hand, on the upper surface of the main body wafer 100 provided with the visible light sensor and the infrared sensor, an annular film 118 made of Al is formed only at the annular joint for the infrared sensor. Then, the annular film 144 of the cap wafer 150 is formed.
When the annular film 118 of the main body wafer 100 is bonded to the annular film 118 by pressure bonding, a cap is formed only on the visible light sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device, a camera and a vehicle equipped with an infrared sensor and a visible light sensor.

[0002]

2. Description of the Related Art An infrared sensor for detecting heat is excellent in that it can be used even in a situation where it is difficult to detect light, such as at night or indoors, and it can detect an object at a relatively long distance. It has excellent characteristics. Therefore, it has been put to practical use as a camera installed in an automobile, a security camera, and the like.

On the other hand, a visible light sensor can clearly capture an image of an object in a situation where light can be detected.

Therefore, in recent years, efforts have been made to develop a detector equipped with an infrared sensor and a visible light sensor. Since this detector can detect light and heat with one detector, a clearer image can be obtained under a wider range of conditions than a detector equipped with only one type of sensor.
As such a detector, there is a photodetector that simultaneously uses a camera equipped with an infrared sensor and a camera equipped with a visible light sensor.

[0005]

However, such a photodetector has the following drawbacks. 13 (a) to 13 (c) are diagrams respectively showing, in order, the arrangement of cameras in a conventional detector, the human detection state and the image formation state by a vehicle equipped with the detector.

As shown in FIG. 13A, in the conventional detector, the position of the infrared sensor and the position of the visible light sensor formed in different cameras are apart from each other, and the optical axes of the respective sensors are different from each other. The shift becomes large, and the view range of each camera also greatly differs. Then, as shown in FIG.
As shown in (b) and (c), when processing the red ray and visible ray data captured by the camera into one image,
The deviation between the image position based on the infrared sensor data and the image position based on the visible light sensor data becomes large. Further, the deviation between the position of the image and the actual position of the image due to the data of each sensor also becomes large. In particular, when the subject is close to the camera, the positional deviation of image formation becomes large. Therefore, it becomes necessary to correct the positional deviation between the two images by providing the image processing unit, which leads to an increase in cost.

As a method for solving the above-mentioned problems, a device in which an infrared sensor and a visible light sensor are formed on one substrate and a manufacturing method thereof are disclosed in Japanese Patent Laid-Open No. 11-132.
It is disclosed in Japanese Patent Publication No. 860. In order for the device of the above publication to exhibit high functions, an environment in which the infrared sensor is maintained in a vacuum atmosphere for exhibiting high performance, and an environment in which visible light for operating the visible light sensor can be sufficiently incident Are preferably realized at the same time. In the above publication, it is unavoidable to limit the usage and increase the cost for separately maintaining the vacuum. Further, the above publication does not disclose a specific method for realizing those environments at the same time.

An object of the present invention is to provide a plurality of sensors formed on the same substrate by providing a means for selectively enclosing the infrared sensor in a reduced pressure atmosphere so that the infrared sensor and the visible light sensor have high performance at the same time. An object of the present invention is to provide an electronic device that exhibits the above, a manufacturing method thereof, a camera and a vehicle to which the electronic device is applied.

[0009]

In an electronic device of the present invention, a first cell region in which an infrared sensor having at least one thermoelectric conversion element is arranged and a visible light sensor having at least one photoelectric conversion element are arranged. A main body substrate having a second cell region formed therein, and a region where the thermoelectric conversion element is arranged in the first cell region, surrounded by the main body substrate and the cap body, and kept in a reduced pressure atmosphere. A hollow portion and an annular joint portion for holding the hollow portion in a reduced pressure atmosphere.

Thus, the infrared sensor requiring a reduced pressure atmosphere can be individually arranged in the cavity without adversely affecting the detection function of the visible light sensor. Therefore,
A structure suitable for both discrete devices and integrated electronic devices can be obtained.

A first annular film formed on the main body substrate and made of a joining member surrounding the thermoelectric conversion element, and a second annular film made of a joining material formed on the cap body. Further, wherein the annular joint is formed between the first and second annular membranes,
A strong annular joint can be provided by selecting a joining material. The body substrate is made of a semiconductor, and the infrared sensor and the external circuit on the body substrate are electrically connected to each other via an impurity diffusion layer formed in the body substrate across the annular joint. The electrical connection between the infrared sensor and the external circuit makes it possible to achieve a reliable structure.

The cap body is provided with a concave portion forming the hollow portion and a tubular portion surrounding the concave portion, and the main body substrate is provided with an engaging portion that engages with the tubular portion. By doing so, it is possible to obtain an electronic device in which the positional relationship between the main body substrate and the cap body is stable and the bonding is highly reliable.

The cap body has a Si substrate and a semiconductor layer provided on the Si substrate and having a bandgap smaller than 1.1 eV.
It becomes difficult for light close to visible light to enter the area where the infrared sensor is arranged. Therefore, it is possible to avoid the superimposition of the background signal, so that it is possible to secure a large dynamic range for infrared detection, and as a result, an electronic device suitable for detecting an animal or a person can be obtained.

The thermoelectric conversion element may be a bolometer.

The thermoelectric conversion element may be a PN diode.

A plurality of the first and second cell regions are arranged to form a cell array, and each of the first and second cell regions is formed.
By providing the cap body for each cell region, an integrated electronic device can be obtained. At this time,
It is possible to obtain a highly reliable electronic device as compared with the case where the entire cell array is covered with one cap body.

According to the method of manufacturing an electronic device of the present invention, a plurality of first cell regions in which an infrared sensor having at least one thermoelectric conversion element is arranged and a visible sensor having at least one photoelectric conversion element are arranged. Step (a) of preparing a main body substrate having a plurality of second cell regions
A step (b) of forming a cap substrate; and a step of applying a pressing force between the first cell region of the body substrate and the cap substrate in a reduced pressure atmosphere. A step (c) of forming an annular joint between the cap substrate and the cap substrate, and in the steps (a) and (b), a recess is formed in at least one of the main body substrate and the cap substrate. And in the step (c), at least a part of the recess is left as a cavity that is kept in a reduced pressure atmosphere in the portion of the first cell region where the element is arranged. This is a method of forming an annular joint.

According to this method, the manufacturing process of an existing electronic device such as the Si process can be used to mass-produce an electronic device including an infrared sensor and a visible light sensor in both a discrete type and an integrated type. Can be provided. In addition, since the cap body is mounted on each of the first cell regions to form the cavity, even if a defective connection occurs in a part of the cell regions, the other cell regions can be actually used. The yield can be improved in any of the integrated types.

In the step (a), a main body substrate having a plurality of first annular films made of a bonding member surrounding the cavity forming region is prepared, and in the step (b), a bonding material surrounding the cavity forming region. A cap substrate having a plurality of second annular films made of is prepared, and in the step (c), the annular bonding portion is formed between the first and second annular films to bond them together. A stronger annular joint can be formed by selecting the material for use.

In the step (b), the second
The annular film may be formed in a region surrounding the visible light sensor.

By further comprising, before the step (c), a step of forming slits in the cap substrate to divide the cap substrate into a plurality of regions,
When a pressing force is applied to bond the first and second annular films to each other, the stress applied to each of the annular films is made uniform, so that the occurrence of bonding failure due to a large local stress is suppressed. be able to.

In the step (b), a cap substrate having a concave portion surrounded by the second annular film and a plurality of cylindrical portions surrounding the concave portion is prepared in the cap substrate. Since it is only necessary to form the concave portion, it is possible to avoid making the manufacturing process of the main body substrate difficult.

Since the step (c) is performed in a reduced pressure atmosphere having a pressure higher than 10 ^-4 Pa, it is possible to avoid the difficulty of maintaining a high vacuum state.
Practical and suitable for mass production can be performed.

After the step (c), a step of dividing the semiconductor substrate into cells is further included to obtain a discrete type electronic device.

The camera of the present invention comprises an electronic device provided with an infrared sensor and a visible light sensor, and an optical system for introducing infrared light and visible light from the outside into the electronic device. Is at least 1
A first cell region in which the infrared sensor having one thermoelectric conversion element is arranged and a second cell region in which the visible light sensor having at least one photoelectric conversion element is arranged, and In order to keep the cavity in the reduced pressure atmosphere, the cavity being provided in the portion where the thermoelectric conversion element is arranged in the cell region of No. 1 and surrounded by the main body substrate and the cap body and kept in the reduced pressure atmosphere. And an annular joint part.

This makes it possible to individually arrange the infrared sensors requiring a reduced pressure atmosphere in the cavity without adversely affecting the detection function of the visible light sensor. Since the infrared sensor and the visible light sensor are arranged on the same substrate, the axial distance between the optical axis of the infrared sensor and the optical axis of the visible light sensor can be made extremely short. Therefore, it is possible to almost eliminate the deviation between the image captured by the infrared sensor and the image captured by the visible light sensor on the screen of the camera.

The vehicle of this embodiment is a vehicle in which a camera incorporating an electronic device provided with an infrared sensor and a visible light sensor is mounted in a part of the vehicle, and the electronic device is at least one thermoelectric conversion element. And a first cell region in which the infrared sensor having the above is arranged, and a second cell region in which the visible light sensor having at least one photoelectric conversion element is arranged, and the first cell region. Of the thermoelectric conversion element, a hollow portion surrounded by the main body substrate and the cap body and held in a reduced pressure atmosphere, and an annular joint portion for holding the hollow portion in a reduced pressure atmosphere. It has and.

This makes it possible to individually arrange the infrared sensors requiring a reduced pressure atmosphere in the cavity without adversely affecting the detection function of the visible light sensor. Since the infrared sensor and the visible light sensor are arranged on the same substrate, the axial distance between the optical axis of the infrared sensor and the optical axis of the visible light sensor can be made extremely short. Therefore, it is possible to almost eliminate the deviation between the image captured by the infrared sensor and the image captured by the visible light sensor on the screen of the camera. Therefore, it becomes possible to detect a person or an animal existing in the visual field range of the camera earlier while the vehicle is traveling, and it is possible to prevent an accident.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Basic Structure of Electronic Device) FIG.
(A)-(d) is sectional drawing which shows roughly the basic structural example of the electronic device of this invention. Note that FIG.
The element arranged in the cell region 11a of the electronic device shown in (d) is an element forming an infrared sensor, and the element arranged in the cell region 11b is an element forming a visible light sensor. Specific structures of these elements will be described in each of the following embodiments.

The region in which the infrared sensor, whose characteristics are improved by increasing the degree of vacuum, is arranged is sealed in a reduced pressure atmosphere by a cap body. On the other hand, the upper side of the region where the visible light sensor that exhibits sufficient characteristics even under normal pressure may be opened, or may be enclosed by a cap body formed of a material that transmits visible light. . Examples of infrared sensors and visible light sensors include bolometers, diodes, and transistors. Further, the number of elements of this type may be single or plural. Furthermore, a switching element (transistor) may be used in the cell region together with the infrared sensor or the visible light sensor depending on the configuration of the two-dimensional arrayed sensor.

-First Basic Structure Example- As shown in FIG. 1A, the electronic device of the first basic structure example has a main body substrate 10 formed from a Si wafer and a desired region of the main body substrate 10. And a cap body 20A formed from a Si wafer for sealing in a reduced pressure atmosphere. The main substrate 10 includes a cell region 11a in which an infrared sensor element and a circuit for supplying a signal to the infrared sensor element are arranged, and a visible light sensor element and a circuit for supplying a signal to the visible light sensor element. The arranged cell region 11b is provided. On the other hand, the cap body 20A has a cylindrical portion 2 surrounding a substrate portion 21 made of silicon and a concave portion that is a cavity portion 23 held in a reduced pressure atmosphere.
2 and. That is, by using various bonding methods described later, the cell region 11a of the infrared sensor in a reduced pressure atmosphere.
And a cylindrical portion 22 of the cap body 20A are coupled to each other to form an annular joint portion 15 for sealing the cavity portion 23 held in the reduced pressure atmosphere. As a result, the infrared sensor is sealed in the reduced pressure atmosphere by the cap body 20A, and the visible light sensor is exposed to the air atmosphere, so that each sensor can perform its desired function.

Here, as the structure of the concave portion, there is a space formed by removing a part of the flat substrate by etching to a certain depth, and a cylindrical portion which is a closed loop wall on the flat substrate. Therefore, there is a space surrounded by the tubular portion. Although FIG. 1 (a) discloses only a concave portion which is a space surrounded by the cylindrical portion 22, in the present invention, it is formed on the main substrate or the cap substrate or both before forming the cavity. The structure of the recess is not limited to the shape shown in FIG. Further, the shape of the concave portion which becomes the hollow portion 23 is, for example, a cylinder, and may be another shape such as a square pole or a truncated cone. The same applies to each basic structure example and each embodiment described below.

As a method of forming the cylindrical portion surrounding the concave portion, a method of forming a cylindrical portion surrounding the concave portion by leaving a closed loop region of the flat substrate and removing the other region to a certain depth, There is a method of forming a cylindrical portion surrounding a recess by stacking closed loop walls on a flat substrate, and any method may be used.

-Second Basic Structure Example- As shown in FIG. 1B, the cap body 20B in the electronic device of the second basic structure example has a substrate portion 21 and a cavity portion 23 held in a reduced pressure atmosphere. 2 that encloses the recess that becomes
In addition to 2, the Ge filter portion 24 made of Ge having a thickness of about 3 μm is provided. The structure of the main body substrate 10 in the second basic structure example is the same as that of the main body substrate 10 in the first basic structure example. In this case, the substrate portion 21 has a wavelength of about 0.
While the light of 8 μm or more (visible light) is easily transmitted, the Ge filter unit 24 transmits only the light (infrared) of the wavelength of 1.4 μm or more, and converts the visible light of the wavelength of 1.4 μm or less. Blocks light in the near wavelength range. Therefore, it is possible to prevent erroneous detection due to a change in the amount of current of a transistor in the electronic circuit due to the incidence of light close to visible light. Infrared sensors are used to detect human bodies and animals at night, but light close to visible light from cars and lighting
This is because carriers in the drain region of the transistor of the electronic circuit may be excited to cause a reduction in the infrared component detection margin due to superimposition of the background signal.

Further, in order to epitaxially grow a Ge layer on a silicon wafer, a Si layer is formed on the silicon wafer.
_{The 1-x} Ge _x layer may be epitaxially grown so that the Ge component ratio x changes from 0 to 1, and then the Ge layer may be epitaxially grown to a predetermined thickness.

A Si _1-x Ge _x layer is formed on the Ge layer by G
After the epitaxial growth is performed so that the e component ratio x changes from 1 to 0, the Si layer may be epitaxially grown to a predetermined thickness. If the subsequent steps are carried out with the Ge layer exposed, the manufacturing apparatus may be contaminated with Ge. If the surface layer is composed of a Si layer, it may be necessary to perform electronic processing for the next Fresnel lens formation. It is preferable that the Ge layer is not exposed on the outermost surface in that the device manufacturing process can be used as it is.

The layer functioning as a filter may be made of a material containing an element other than Ge. In particular, a material having a bandgap smaller than the bandgap of 1.1 eV of Si absorbs light in a wavelength range longer than 0.8 μm (mainly near infrared rays), and thus diffuses impurities such as transistors arranged in the cell. It is possible to avoid problems caused by exciting carriers in the layer.

The structure of the visible light sensor in the cell region 11b is the same as the structure of the visible light sensor in the first basic structure example.

-Third Basic Structure Example- As shown in FIG. 1 (c), the cap body 20C in the electronic device of the third basic structure example has a substrate portion 21 and a cavity portion 23 held in a reduced pressure atmosphere. 2 that encloses the recess that becomes
In addition to 2, the Ge filter section 24 and the Si layer 25 having a grating pattern 27, which becomes a Fresnel lens having a convex lens function, is engraved on the surface thereof. The structure of the main body substrate 10 in the third basic structure example is the same as that of the main body substrate 10 in the first basic structure example. In the third basic structure example, in particular, light can be effectively concentrated on the existing position of the resistor by the convex lens function of the lattice pattern on the surface, so that an electronic device suitable for miniaturization and high performance can be obtained. .

In the atmosphere, the wavelength range of electromagnetic waves is 3 μm to 5 μm.
And 8 μm to 10 μm, there is a portion with a high infrared transmittance called the “window of the atmosphere”, and infrared rays pass through that band, but the infrared transmittance decreases in the portion other than the window of the atmosphere, so it is detected. It will be a difficult area. The infrared sensor has a wavelength range of 3 μm to 10 μm for the human or animal body.
Since it is detected by infrared rays, the Ge filter layer 24 provides a region close to visible light 0.8 μm to 1.4 μm.
It is possible to accurately detect the target person or animal of the infrared sensor while avoiding superposition of signal charges due to light in the μm range.

In place of the Ge filter layer, SiGe
A filter layer (composition Si _1-x Ge _x ) may be provided. In that case, the frequency band of infrared rays that can be blocked by the Ge component ratio x varies in the range of 0.8 μm to 1.4 μm. Therefore, by providing the SiGe filter layer, there is an advantage that the cutoff frequency range can be adjusted according to the purpose.

The structure of the visible light sensor in the cell region 11b is the same as the structure of the visible light sensor in the first basic structural example.

-Fourth Basic Structure Example- As shown in FIG. 1D, in the electronic device of the fourth basic structure example, a main body substrate 10 made of Si and a desired region of the main body substrate 10 are decompressed in an atmosphere. A cap body 20D made of Si for sealing the inside is provided. On the main body substrate 10, a large number of cell regions 11a in which an infrared sensor and a circuit for supplying a signal to the infrared sensor are arranged,
A large number of cell regions 11b in which a visible light sensor and a circuit for supplying a signal to the visible light sensor are arranged are provided. On the other hand, the cap body 20D includes the substrate portion 21.
And a large number of tubular portions 22 surrounding a recessed portion that is to be a cavity 23 that is held in a reduced pressure atmosphere. That is, by using various bonding methods described later, a part of the cell region 11a of the infrared sensor and each cylindrical portion 22 of the cap body 20D in a reduced pressure atmosphere.
Join with. As a result, the infrared sensor is sealed in the reduced pressure atmosphere by the cap body 20D, and the visible light sensor is exposed to the air atmosphere, so that each sensor can perform its desired function.

The substrate portion 21 has a notch for partitioning the substrate portion 21 into cell regions, and each cell region is divided at the notch during or after joining. Even if there is a slight difference in pressing force (compression force) between cells due to the bonding thickness of each cap body or the deformation of the wafer, elastic deformation at the notch allows the pressing force of the bonding in each cell to be minimized. It is configured to be uniform.

Further, in FIG. 1 (d), the cap body 20D has only the substrate portion 21, but it may have a Ge cap portion and further has a lens function such as a Fresnel lens on the surface. You may have it.

FIGS. 1A to 1D show a state in which the main body substrate and the cap body are joined to each other by joining Si to each other. However, in general, the manufacturing process is easier using the joining of metals than the joining of Si. Therefore, an example of the structure of the joint will be described below.

(Structural example of the joint) FIGS. 2 (a) to 2 (d)
FIG. 3 is a cross-sectional view schematically showing a structural example of a bonding portion for holding a vacuum of the electronic device of the present invention.

-Structural Example of First Bonding Section- As shown in FIG. 2A, in the structural example of the first bonding section,
An annular film 12 made of a metal (for example, aluminum) that is a bonding material is provided on the main body substrate 10, and a metal (for example, aluminum) that is a bonding material is formed at the tip of the tubular portion 22 of the cap body 20. Annular joint 26
Is provided. Then, each annular film 1 in a reduced pressure atmosphere
By forming a ring-shaped joint 15 by bonding 2, 26 to each other by hydrogen bonding or the like, the cavity 23 on the cell region 11a of the infrared sensor is sealed in a reduced pressure atmosphere. on the other hand,
The upper part of the cell region 11b of the visible light sensor is open.

In addition, in the structural example of the first joint portion and the structural examples of other joint portions which will be described later, the metal as the joining material is not only Al but also Cu, Au, Ag, Al--Cu alloy, and the like. There is a metal or an alloy, and any of them may be used.
Further, as the bonding material, it is possible to use a material other than metal, but in particular, in the case of metal, it can be said that it is suitable for the present invention in that it is easy to bond under a low temperature and low vacuum atmosphere. .

-Structural Example of Second Bonded Section- As shown in FIG. 2B, in the structural example of the second bonded section,
An annular protrusion 14 made of an insulating film is provided around the infrared sensor of the main body substrate 10, and the annular film 12 is provided on a region inside the annular protrusion 14. On the other hand, an annular film 26 is provided at the tip of the tubular portion 22 of the cap body 20. Then, in the depressurized atmosphere, the tubular portion 22 is moved to
In the state of being fitted in 4, the respective annular films 12 and 26 are joined to each other to form the annular joint portion 15, so that the cavity portion 23 on the cell region 11a of the infrared sensor is sealed in the reduced pressure atmosphere. That is, the annular protrusion 14 functions as an engaging portion that engages with the tubular portion 22. However, the main body substrate 10 has a cylindrical portion 2
Although the concave portion having the inner side surface that engages with the outer side surface of 2 is provided as the engaging portion, the inner side surface of the tubular portion 22 and the outer side surface of the engaging portion of the main body substrate may be engaged with each other. The upper part of the cell region 11b of the visible light sensor is open.

It should be noted that it is also possible to use the joining of Si instead of the joining of metals, and in that case, it is not necessary to provide the annular films 12 and 26.

According to this structural example of the joint portion, the cap body 20 can be reliably fixed on the main body substrate 10. Therefore, the structural example of this joint portion is an electronic device having a plurality of infrared sensor cell regions 11a. The structure is particularly suitable for.

-Structural Example of Third Junction-As shown in FIG. 2C, in the structural example of the third joint,
An annular protrusion 14 made of an insulator whose inner surface is a tapered surface is provided around the infrared sensor of the main body substrate 10, and an annular film 12 is provided on a region inside the annular protrusion 14. On the other hand, the outer surface of the tubular portion 22 of the cap body 20 is also a tapered surface having substantially the same inclination as the tapered surface of the inner side surface of the annular protruding portion 14, and the annular film 2 is provided at the tip of the tubular portion 22.
6 is provided. Then, in a depressurized atmosphere, the annular joints 15 are formed by joining the annular membranes 12 and 26 in a state where the inner surface of the annular projection 14 and the outer surface of the tubular portion 22 are fitted together. The cavity 23 on the cell region 11a of the infrared sensor is sealed in a reduced pressure atmosphere. Also in this case, the annular protrusion 14 functions as an engaging portion that engages with the tubular portion 22. The main body substrate 10 is provided with a recess having an inner side surface that engages with the outer side surface of the tubular portion 22 as an engaging portion. It may be engaged. The upper part of the cell region 11b of the visible light sensor is open.

It should be noted that it is also possible to use the joining of Si instead of the joining of metals, and in that case, it is not necessary to provide the annular films 12 and 26.

According to this structural example of the joint portion, it is easy to align the cap body 20 on the main body substrate 10. This structural example of the joint portion is an electronic device having a plurality of infrared sensor cell regions 11a. The structure is particularly suitable for.

-Structural Example of Fourth Bonded Section- As shown in FIG. 2D, in the structural example of the fourth bonded section,
An annular protrusion 14 made of an insulator whose inner surface is a stepped surface is provided around the infrared sensor of the main body substrate 10, and the annular film 12 is provided on a region inside the annular protrusion 14. . On the other hand, the outer surface of the cylindrical portion 22 of the cap body 20 is a stepped surface that engages with the stepped surface of the inner side surface of the annular protrusion 14, and the annular film 26 is provided at the tip of the cylindrical portion 22. . Then, in a reduced pressure atmosphere, the annular protrusion 1
In a state where the inner side surface of 4 and the outer side surface of the tubular portion 22 are fitted to each other, the annular membranes 12 and 26 are joined together to form the annular joint portion 1.
By forming 5, the cell area 11 of the infrared sensor
The cavity 23 above a is sealed in a reduced pressure atmosphere.

In this case as well, the annular projection 14 has the cylindrical portion 2
It functions as an engaging portion that engages with 2. The cylindrical portion 22 is provided with a stepped outer surface, and the main body substrate 10 is provided with a concave portion having a stepped inner surface that engages with the main substrate 10 as an engaging portion. The inner side surface may be provided, and the main body substrate may be provided with an engaging portion having a stepped outer surface. It should be noted that it is also possible to use the joining of Si instead of the joining of metals, and in that case, it is not necessary to provide the annular films 12 and 26. The cell region 11b of the visible light sensor
The upper part of is open.

According to this structural example of the joint portion, it is easy to align the cap body 20 on the main body substrate 10. This structural example of the joint portion is an electronic device having a plurality of infrared sensor cell regions 11a. The structure is particularly suitable for.

(Electrical Connection Structure) FIGS. 3 (a) and 3 (b)
Are, respectively, a plan view showing an example of an electrical connection structure suitable for the electronic device of the present invention, a line IIIa-IIIa, and a line IIIb-II.
It is sectional drawing in the Ib line. However, FIG. 3A shows a planar structure of the electronic device without the cap body.

As shown in FIGS. 3 (a) and 3 (b), the main body substrate 10 and the cap body are mechanically connected to each other by the joining of the annular films 12 and 26, and a vacuum state is established between them. A cavity 23 that is held is formed. Further, in the cavity 23 on the main body substrate 10, as an infrared sensor IRS, an element 40 such as a bolometer shown by a broken line,
Gate electrode 31, source region 32 and drain region 3
N-channel switching transistor 3 having
0 and are provided. The switching transistor 30 controls the electrical connection between the infrared sensor IRS in the region sealed by the cap body 20 and the external circuit. Then, the on / off of the electrical connection between the element 40 arranged in the region sealed by the cap body 20 and the external circuit is controlled. The drain region 33 and the gate electrode 31 of the switching transistor 30 are provided in the region surrounded by the cap body 20. As shown in FIG. 3A, the source region 32 is formed so as to cross the annular films 12 and 26 in the substrate body 10. In addition, in the region of the cap body 20 located immediately below the tubular portion, each annular film 1 is formed in the substrate body 10.
Impurity diffusion layers (N + type diffusion layers) 32, 35 and 36 which are formed so as to cross 2, 26 and function as wirings are provided.

In addition, in the region of the main body substrate 10 where the cap is not formed, as the visible light sensor VLS, P
N diode 70, gate electrode 78, source region 79
And amplifying transistor 7 having drain region 80
1, a read switching transistor 72, and a reset switching transistor 73 are provided. The reset switching transistor 73 controls the connection between the PN diode 70 and the gate 78 of the amplification transistor 71. The potential from the N layer of the PN diode 70 is transmitted to the gate electrode 78 of the amplifying transistor 71 via the read switching transistor 72 and the wiring 51f. Then, the output potential of the amplifying transistor 71 is the N of the PN diode 70.
It is determined by the gate bias determined by the potential of the layer.

An interlayer insulating film 41 made of silicon oxide, which covers the switching transistor 30 and the main substrate 10, and a passivation film 42, which covers the interlayer insulating film 41, are formed on the main substrate 10. Further, a contact layer 31a connecting the gate electrode 31 of the switching transistor 30 and the impurity diffusion layer 36,
A first wiring 51a connecting the source region 32 of the switching transistor 30 and an external circuit (not shown) to each other.
A second wiring 51b connecting the impurity diffusion layer 36 and an external circuit (not shown) to each other, and a third wiring connecting the drain region 33 of the switching transistor 30 and the element 40.
A wiring 51c, a fourth wiring 51d connecting the element 40 and the impurity diffusion layer 35 to each other, a drain region 79 of the impurity diffusion layer 35 and the amplification transistor 71, and a fifth wiring 51e connecting the external circuit to each other are provided. It is provided. That is, the element 40 and the switching transistor 30 are connected via the third wiring 51c and the drain region 33. Further, the element 40 includes the fourth wiring 51.
d, connected to an external circuit via the impurity diffusion layer 35 and the fifth wiring 51e.

By adopting such an electrical connection structure, there is no metal wiring immediately below the annular joint 15 existing between the annular film 26 of the cap body 20 and the annular film 12 of the main body substrate 10. , It effectively prevents the wiring from breaking due to a short circuit between the wirings or the pressing force (crimping force) when connecting the annular connecting parts to each other, or the reliability of the connection from being deteriorated due to a part of the breaking. be able to. Further, since it becomes easy to cover the interlayer insulating film 41 with the passivation film 42 in the cavity 23, it is possible to prevent degassing or the like generated from the interlayer insulating film 41 from entering the cavity 23. The vacuum state of the hollow portion 23 can be maintained well.

The external circuit may be formed on the main body substrate 10 in a region not covered by the cap body 20, or may be provided in a portion different from the main body substrate.

Further, as shown in FIG. 3B, in the visible light sensor VLS, the N layer of the PN diode 70 also serves as the N ⁺ regions (source / drain regions) of the reset switching transistor 73 and the read transistor 72. ing. Also in the visible light sensor, the substrate and the gate electrode are covered with the interlayer insulating film 41 and the passivation film 42.

In the structure of the electronic device shown in FIGS. 3A and 3B, the cap body 20 is provided so as to surround the element 40 in the cell region and the switching transistor 30 (particularly the drain region 33). ing. If the cap body 20 is provided with a Ge layer having a filter function, superimposition on the infrared signal charge by the electric charges excited in the drain region of the switching transistor 30 in the cell region by visible light and light in the wavelength region close to visible light. It can be avoided. Further, even if the Ge layer is not provided on the cap body 20, a filter made of Ge or the like may be provided at a position where light can be prevented from entering at least the switching transistor 30. Furthermore, if the cap body 20 is not provided with a filter portion such as a Ge layer, it is not necessary to surround the switching transistor 30 (particularly the drain region) with the cap body 20.

(First Embodiment) Next, the first embodiment, which is an example in which the electronic device of the present invention is applied to a discrete type device, will be described.

4 (a), (b) and (c) are a sectional view, an electronic circuit diagram and an electronic circuit diagram of the visible light sensor according to the first embodiment of the present invention. Since the structure of the visible light sensor is well known here, the illustration and description of the cross-sectional view are omitted.

As shown in FIG. 4A, the infrared sensor of this embodiment has a Si substrate 110 having a thickness of about 300 μm.
A resistive element (bolometer) 120 provided on the Si substrate 110, a switching transistor 130 formed on the Si substrate 110 for turning on / off a current to the resistive element 120, and a resistive element 120. Cap body 14 for holding the mounted area in a reduced pressure atmosphere
It has 0 and. The size of the entire infrared sensor IRS is about 20 to 100 μm for a single element, and is about several mm for a cell array in which 128 × 128 elements are arranged, when a two-dimensional array is formed. S
A resistor 111 patterned in a zigzag shape, a silicon nitride film 112 and a silicon oxide film 113 supporting the resistor 111, and a resistor 11 are formed on the i-substrate 110.
1, a BPSG film 116 and a passivation film (silicon nitride film) 117 are provided to cover the top surface of the film 1. The silicon oxide film 113, the BPSG film 116, and the silicon nitride film 112 are patterned together with the resistor 111 in a zigzag shape, and extend up to the top of the Si substrate 110. Zigzag-shaped resistor 111, silicon oxide film 1
13, BPSG film 116 and passivation film 117
Cavities 119 and 143 held in vacuum are provided below and above, respectively, and the cavities 119 and 143 are
The silicon oxide film 113, the BPSG film 116, and the silicon nitride film 112 are connected to each other through the gaps and the sides of the integrated portions. Then, the resistor 111, the silicon oxide film 113, the BPSG film 116, the passivation film 117, and the silicon nitride film 112 are all provided in a zigzag shape on the cavity 119.

The material of the resistor 111 includes Ti, TiO, polysilicon, Pt and the like, and any of them may be used.

In the passivation film 117, the annular film 11 made of a soft metal material (such as aluminum) is formed on the portion of the cap body 140 located below the cylindrical portion 142.
8 is provided, and an annular film 144 made of a soft metal material (such as aluminum) is also provided at the tip of the tubular portion 142, and the cap is formed by the annular joint 15 formed between the annular films 118 and 144. Body 140 and Si substrate 110
The cavities 119 and 143 existing between and are held in a reduced pressure atmosphere (vacuum state). That is, the cavity 11
Due to the presence of 9,143, the resistor 111 is
It is thermally insulated from the substrate 110 and is configured to maintain a high conversion efficiency from infrared rays to heat.

Further, the substrate portion 141 of the cap body 140
Is about 3 μm thick on a silicon substrate of about 300 μm thick.
m, and a Si layer having a Fresnel lens formed on the surface and having a thickness of about 1 μm are epitaxially grown. A hollow portion having a depth of several μm or more is formed by the cylindrical portion 142 of the cap body 140. It should be noted that the portion that becomes the window portion into which infrared rays enter the element may be thinned by etching or the like.

Further, the switching transistor 130
Includes a source region 131, a drain region 132, and a gate electrode 133. Then, the drain region 132
Is formed below the cylindrical portion 142 of the cap body 140, and the drain region 132 is configured to function as a wiring for connecting a signal between the resistor 111 sealed in a vacuum state and an external member. There is.

Although not shown in FIG. 4A, a Peltier element for cooling the resistance element is attached to the lower surface of the Si substrate 110. This Peltier element is an element that utilizes the heat absorption effect associated with the movement of carriers passing through the Schottky junction portion, and various Peltier elements having a known structure can be used in the present embodiment.

As shown in FIG. 4B, the resistance element 120
Is connected to the wiring 135 that supplies the power supply voltage Vdd, and the other end of the resistance element 120 is connected to the drain region 132 of the switching transistor 130. Also,
The gate of the switching transistor 130 has a wiring 1
An ON / OFF switching signal is input via 36, and the source of the switching transistor 130 is a reference resistance for detecting the amount of infrared rays received by the resistance element 120 via a wiring 138 having a standard resistance at the other end. Also, the substrate 110 is connected to a detector (not shown) and is grounded. That is, when the temperature of the resistance element 120 changes according to the amount of infrared rays and the resistance value changes, the potential changes due to the resistance division between the resistance element 120 and the reference resistance connected via the wiring 138. The corresponding amount of infrared rays is detected from this change in potential.

In the infrared sensor of the discrete type device, an operational amplifier for amplifying the output from the bolometer may be provided on the substrate. In that case, in addition to the bolometer and the switching transistor of the present embodiment, the operational amplifier can be arranged in the region sealed by the cap body.

FIG. 4C is an electronic circuit diagram of the visible light sensor of the infrared sensor IRS and the visible light sensor according to the first embodiment of the present invention.

As shown in FIG. 4C, in the visible light sensor of this embodiment, a photodiode 191 made up of a PN diode and a gate electrode having an N of the photodiode 191 are used.
Amplification transistor 192 connected to the layer for controlling data output of the photodiode 191, a reset switching transistor 193 provided between the N layer of the photodiode 191 and the wiring 195, and an N of the photodiode 191. And a read switching transistor 194 provided between the layer and the gate electrode of the amplifying transistor 192. Amplifying transistor 1
The drain region of 92 is connected to a terminal that supplies the power supply voltage Vdd via a wiring, and the source region is connected to a terminal that supplies the ground voltage Vss via a wiring. In addition, the reset switching transistor 193
The gate of is connected to an external circuit via a wiring 197,
The gate of the read switching transistor 194 is connected to an external circuit via a wiring 198.

In the visible light sensor, when the reset switching transistor 193 is turned on, a reverse bias of 5 V, for example, is applied to the PN diode 191. At this time, when light enters the depletion layer of the PN diode 191, carriers are excited, and an amount of electrons corresponding to the amount of light of the N layer is accumulated, the value of the reverse bias changes, for example, becomes 3V.
When the value of the reverse bias changes, the bias of the gate of the amplifying transistor 192 changes via the reading transistor 194, and the current amount of the amplifying transistor changes. Therefore, the amount of light can be detected from the change in the amount of current.

Next, the manufacturing process of the infrared sensor IRS mounted on the electronic device of this embodiment will be described. 5A to 5F are cross-sectional views showing the manufacturing process of the infrared sensor IRS according to the first embodiment of the present invention. Further, FIGS. 6A to 6E are plan views showing a process of forming the bolometer and its peripheral region. And FIG.
6A is a sectional view taken along line Va-Va shown in FIG. 6C, FIG. 5B is a sectional view taken along line Vb-Vb shown in FIG. 6D, and FIG. Vd-V shown in 6 (e)
It is sectional drawing in the d line. Since the visible light sensor is manufactured by a known method, its description and illustration are omitted.

First, in the step shown in FIG. 5A, a large number of holes 112x as shown in FIG. 6A are formed on the Si substrate 110.
A flat plate-shaped silicon nitride film 112 is formed. Next, using the silicon nitride film 112 as a mask, the Si substrate 110 is dry-etched to form a bottomed hole just below the hole 112x, and then the hole is enlarged in the horizontal and vertical directions by wet etching. A cavity 119x having a depth of about 1 μm is formed as shown in FIG. At this time, in FIG. 5A, it is drawn that the wall portions 110x always exist between the small hollow portions 119x, but the hollow portions 119x are connected to each other below the approaching holes 112x. Then, it may be a relatively large cavity.

Then, when the polysilicon film 113 is formed on the silicon nitride film 112, the polysilicon film 11 is formed.
Since 3 does not completely cover the hole 112x, FIG.
As shown in (c), a small hole 113x is also formed in the polysilicon film 113.

Next, in the step shown in FIG. 5B, the polysilicon film 113 is thermally oxidized to form a silicon oxide film 113a. With this silicon oxide film 113a, the holes 1 are formed.
13x is blocked. Further, the silicon oxide film 113a
After depositing a resistor film made of a conductor such as Ti on the
This is patterned to form a resistor 111 having a serpentine pattern as shown in FIG.

Then, after depositing a polysilicon film on the substrate, the polysilicon film is patterned to form the gate electrode 1.
33 is formed. Then, impurities (for example, n-type impurities such as arsenic and phosphorus) are implanted into regions of the Si substrate 110 located on both sides of the gate electrode 133, and the source region 1
31 and the drain region 132 are formed.

Next, in a step shown in FIG. 5C, a BPSG film 116 is deposited on the substrate so as to cover the entire upper surface of the substrate including the gate electrode 133 and the resistor 111. This BPS
Although the G film 116 is depicted as having a relatively small thickness in FIGS. 5C to 5F, it is preferably provided as a thick interlayer insulating film that is flattened by reflow.

Next, in the step shown in FIGS. 5D and 6E, the portion of the BPSG film 116 located in the gap portion of the resistor 111 is removed. At this time, the BPSG film 11
Part of 6 remains and covers the resistor 111.
Then, a passivation film 117 made of silicon nitride is deposited on the substrate. This passivation film 11
7 is a resistor 111 and a switching transistor 130.
This is to prevent moisture and humidity from entering the inside. Then, of the passivation film 117, the silicon oxide film 113, and the silicon nitride film 112, the resistor 1
The part located in the gap of 11 is removed. This allows
The formation of the resistance element (bolometer) 120 is completed. At this time, the wall portions 110x existing between the cavity portions 119x are
Is also removed and a wide cavity 119 is formed. Further, the resistor 111 is composed of the silicon oxide film 113 and the BPSG film 11.
6 and the passivation film 117.

Next, in the step shown in FIG. 5E, the resistor 111 and the switching transistor 130 are formed on the region of the passivation film 117 around the resistor 111.
A ring-shaped film 118 made of metal (aluminum (Al)) having a thickness of about 600 nm is formed so as to surround the ring. At this time, part of the annular film 118 is the switching transistor 1.
It is located above the drain region 132 of 30.

Although not shown in FIG. 5E, wirings 51a to 51 as shown in FIGS. 3A and 3B are also provided.
e is formed. That is, after forming a contact hole penetrating the passivation film 117 and the interlayer insulating film 116 to reach the impurity diffusion layer (including the source / drain regions) and the resistor 111 of the bolometer, the contact hole is filled and the contact hole is formed on the passivation film. The extending wiring is formed.

Next, in the step shown in FIG. 5 (f), a substrate portion 141 serving as a window for passing infrared rays in the wavelength region of 1.4 μm or more and a cylindrical portion 142 surrounding the concave portion are formed on the silicon substrate.
A cap body 140 having an annular film 144 made of Al and provided on the tip of the tubular portion 142 is prepared. Then, the annular film 144 on the cap body 140 and the Si substrate 1
The annular film 118 on 10 is aligned with each other to form an annular joint 15 for joining the two. At this time, the entire cell region has substantially the same planar shape and circuit structure as shown in FIGS. 3 (a) and 3 (b).

Here, each of the annular films 118 and 144 is made of Al.
It is formed by patterning the Al film formed by sputtering. Then, the annular film 118,
FAB (First Atom Beam) processing in 144, that is, Ar
A dangling bond is exposed on the surface of Al by performing a treatment of irradiating atoms, and then both are bonded by pressure bonding. Details of this joining step will be described later.

-Method for forming cap body-FIGS. 7A to 7F are sectional views showing a method for forming a cap body used in the electronic device of this embodiment.

First, in the step shown in FIG. 7A, a cap wafer 150 is prepared by sequentially epitaxially growing a Ge layer and a Si layer on a silicon wafer. In order to epitaxially grow a Ge layer having a thickness of about 3 μm on a silicon wafer, as described above, the Si _1-x Ge _x layer is epitaxially grown on the silicon wafer so that the Ge component ratio x changes from 0 to 1. After that, the Ge layer is epitaxially grown to a predetermined thickness. Also, after that,
After a Si _1-x Ge _x layer is epitaxially grown on the Ge layer so that the Ge component ratio x changes from 1 to 0, a Si layer having a thickness of about 1 μm is epitaxially grown. Then, on the surface of the Si layer, a Fresnel lens that serves as a convex lens for focusing infrared rays on each infrared sensor IRS is formed.

Then, with the surface of the cap body wafer 150 on which the Fresnel lens is formed facing downward, as shown in FIG.
As shown in (a), Ge of the cap body wafer 150
An Al film 151 having a thickness of about 600 nm is formed on the surface facing the layer and the Si layer by a vapor deposition method, a sputtering method, or the like.

Next, in the step shown in FIG. 7B, the Al film 1 is formed.
A resist pattern (not shown) is formed on 51, and the Al film 151 is etched using the resist pattern as a mask. As a result, the annular film 144 of the cap body for the infrared sensor IRS and the annular film 144a surrounding the portion located above the visible light sensor VSL are simultaneously formed.

Next, in the step shown in FIG. 7C, the annular film 1 is
Dry etching (RIE) is performed using 44 and the annular film 144a as a mask. As a result, on the cap body wafer 150, the cylindrical portion 142 surrounding the recessed portion that becomes the cavity of each infrared sensor IRS cap body, and the visible light sensor IRS.
The cylindrical portion 14 surrounding the concave portion of the portion to be located above
2a and 2a are formed at the same time. At this time, the cap body wafer 150 is processed by the substrate portion 141 having the remaining portion of the silicon wafer, the Ge layer, the Si layer, the Fresnel lens, and the like, and the tubular portion 142 on which the annular film 144 is formed, and the annular film 144a is formed. The height with respect to the formed cylindrical portion 142a, that is, the depth of the recess is several μm or more.

As a method of forming the cap body, instead of the bulk Si substrate, an oxide insulating layer (for example, so-called BO) is used.
It is also possible to use an SOI substrate having an (X layer). In that case, since the Si substrate can be etched under the condition that the etching selection ratio between the insulating layer and the Si substrate is high, it becomes possible to reliably stop the formation of the concave portion at the insulating layer portion.

Next, in the step shown in FIG. 7D, with the substrate portion 141 of the cap body wafer 150 facing upward,
By the dry etching using ICP-RIE, the substrate portion 141 is formed on the substrate portion 141 of the cap body wafer 150.
To form a notch 152 for individually forming each cap body. Then, as shown in FIG.
The main body substrate 100 having a structure as shown in FIG. 5A is prepared, and the annular film 118 made of Al having the shape shown in FIG. 5F or FIG. It is formed only at the junction site of IRS.

Next, in the step shown in FIG. 7 (e), the annular film 11 is formed only on the bonding portion of the cap body for the infrared sensor IRS.
The cap body wafer 150 is placed on the upper surface of the main body substrate 100 on which 8 is formed, and a bonding step by pressure bonding as shown in FIG. Then, of the cap bodies, the cap body 140 for the infrared sensor IRS can be attached to the main body substrate 100 by joining the annular film 144 and the annular film 118 formed at the joining portion on the main body substrate 100. Is the cylindrical portion 142a of the visible light sensor VSL.
Does not adhere to the main body substrate 100 because the annular film is not formed at the bonding site on the main body substrate 100.

In the step shown in FIG. 7C, etching may be performed on the substrate so that only the cylindrical portion 142 for surrounding the infrared sensor IRS remains. However, in the present embodiment, etching is performed by leaving the tubular portion 142a for the visible light sensor VSL in addition to the tubular portion 142 for the infrared sensor IRS. This is because the etching amount can be reduced by leaving the cylindrical portion for the visible light sensor VSL. Therefore, the inner circumference remains circular while the outer circumference is square, etc.
It is preferable to increase the thickness of the cap body of the visible light sensor VSL that is removed later.

Next, in the step shown in FIG. 7F, the cap body wafer is divided into individual cap bodies at the notch 152 of the cap body wafer 150. Furthermore, the main substrate 10
0 is cut out for each discrete device by dicing. As a result, the infrared sensor IRS covered with the main substrate 100 and the infrared cap body 140.
And a visible light sensor VSL exposed on the main body substrate 100 (see FIG. 3A).
Is obtained.

-Details of Joining Process by Pressure Bonding- FIG. 8 is a cross-sectional view schematically showing the structure of an apparatus used for pressure bonding. As shown in the figure, in the chamber 160, a supporting member 161 for applying pressure for pressure bonding,
A broadband rotary pump 162 for maintaining a vacuum inside the chamber 160 and irradiation devices 163, 164 for irradiating Ar are attached. Arranged from the irradiation devices 163 and 164 to the annular films 118 and 144 (see FIG. 7D) with the main body wafer 100 above and the cap body wafer 150 below.
Irradiate with an atomic beam. By this process, the annular film 11
The contaminants and oxide film on the Al surface constituting 8,144 are removed. After that, the degree of vacuum in the chamber 160 is reduced to 10
^-4 Pa level, at a room temperature (for example, about 30 ° C.), a pressure of 0.5 MPa to 20 MPa is applied to both annular membranes 1.
By applying between 18 and 144, each annular film 11
8, 144 are joined together.

At this time, the annular film 118,
The Ar adsorbed on the surface may be expelled by heating 144 to about 150 ° C.

Moreover, since dangling bonds can be exposed on the surface of a metal such as Al by irradiating O atoms or other neutral atoms instead of irradiating Ar atoms,
The same effect as this embodiment can be obtained.

As the metal used for joining, other metals (including alloys) of Al can be used. In particular, Cu, Au, Ag, Al—Cu alloys having a low melting point are at room temperature or close to room temperature. Bonding at low temperature is possible. As these metals, metals of the same kind may be used, or metals of different kinds may be used.

As the joining method, there are a method of using not only thermocompression but also ultrasonic joining, a method of giving composition deformation at room temperature and joining, and any method may be used.

In particular, by bonding at a vacuum degree of 10 ^-2 Pa to 10 ^-4 Pa or less, it is possible to avoid the difficulty of maintaining a high vacuum state, so that the bonding is practical and suitable for mass production. Can be done.

According to the present embodiment, unlike the conventional device described above, the entire cell array including many sensors is not held in a vacuum state, but a wafer on which many infrared sensors and visible light sensors are formed is used. Since only each infrared sensor can be individually sealed in a vacuum state and each visible light sensor can be opened, it can be easily applied to a discrete type element.

In particular, this embodiment is a manufacturing method suitable for practical use because the manufacturing process of the electronic device, particularly the NMOS or CMOS process can be used as it is.

Further, since the enclosed portion is formed by joining soft metals such as aluminum instead of forming the enclosed portion by soldering as in the prior art, it can be easily applied to miniaturization of the element. Becomes

Further, according to the manufacturing process of this embodiment, even when a large number of discrete devices each having an infrared sensor and a visible light sensor are formed on a wafer, the cap body is bonded only to the area of each infrared sensor, and visible. The light sensor can be opened. In particular, as shown in FIG. 7D, by forming the cut portion 152 in the substrate portion 141, the stress applied to the joint portion can be made uniform for each cell, so that a large stress locally occurs during the joint. Does not work, and the reliability of the connecting portion can be improved.

Further, in each of the above embodiments, the upper surface of each transistor included in each visible light sensor is covered with a film of a light-shielding material such as Al or W, and the source / drain regions of each transistor are shielded from light. ing.

(Second Embodiment) FIG. 9 shows a second embodiment of the present invention.
FIG. 3 is an electric circuit diagram for explaining the configuration of the electronic device according to the embodiment of FIG.

On the main body substrate 100, for example, a plurality of infrared sensors IRS arranged in the row direction, for example, 128 lines, and a plurality of visible light sensors VLS arranged in the row direction, for example, 128 lines, are arranged in the column direction, for example, about 128 lines. , A matrix-shaped cell array is provided by being alternately arranged, and FIG. 9 shows a part of the cell array.

Here, the infrared sensor IRS has a bolometer 201 and a switching transistor 202. In the infrared sensor IRS, the gate electrode of the switching transistor 202 is the vertical scanning circuit 20.
9 (V-SCAN) select lines SEL-1, SE extending from
It is connected to L-3 ... (128 lines). Further, one end of the bolometer 201 is connected to the power supply line 205, and the source of the switching transistor 202 extends from the ground through the reference resistors Ra, Rb ... (128 U) to the data lines 204a, 204b ... (128 lines). )It is connected to the.

On the other hand, the visible light sensor VLS includes a photodiode 301 which is a PN diode, an amplification transistor 302 whose gate electrode is connected to the N layer of the photodiode 301, and which controls the output of data of the photodiode 301, and a photo transistor. A read switching transistor 303 provided between the N layer of the diode 301 and the gate electrode of the switching amplification transistor 302.
And the N layer of the photodiode 301 and the power supply line 2
05, and a reset switching transistor 304 interposed therebetween. Here, the gate electrode of the read switching transistor 303 is the select line SE extending from the vertical scanning circuit 209 (V-SCAN).
L-2, SEL-4 ... (128 lines) are connected. The drain of the amplifying transistor 302 is connected to the power supply line 205, and the source is connected to the data lines 204a, 204b ... That extend from the ground through the reference resistors Ra, Rb. . Further, the data lines 204a, 204b ... Are connected to the output amplifier 206 via the switching transistors SWa, SWb. The gate electrodes of the switching transistors SWa, SWb ...
Signal lines 207a, 207b ... (128 lines) extending from the horizontal scanning circuit 208 (H-SCAN) are connected.

FIG. 10 is a timing chart showing the method of controlling the electronic device of this embodiment. First, control of the infrared sensor IRS connected to the selection line SEL-1
This will be described below with reference to FIG. When the select line SEL-1 is driven by the control of the vertical scanning circuit (V-SCAN), the switching transistors 202 of the cells A1, B1 ... Are turned on, and the bolometer 201 has the reference resistors Ra, Rb. The voltage via .. is respectively supplied.
On the other hand, the horizontal scanning circuit (H-SCAN) sequentially drives the switching transistors SWa, SWb ... And the data Da1, Db1 ... Of the cells A1, B1 ...
Is output from the output amplifier 206.

Select lines SEL-2 and SEL at this time
Control of the visible light sensor VLS connected to -3 is shown in FIG.
This will be described with reference to FIG. Initially, a reverse bias of, for example, 5 V is applied to the photodiode 301 and reset to the initial state. In this state, the electrons excited by the light incident on the depletion layer are accumulated, and when the selection line SEL-2 is driven by the control of the vertical scanning circuit (V-SCAN), the read switching transistor 303.
Is turned on, and the gate bias of the amplifying transistor 302 changes. As a result, the output potential from the amplifying transistor 302 changes as much as the reverse bias value changes due to the incidence of light on the photodiode 301. Then, the change in the output potential changes in each cell A2.
The data Da2, Db2 ... Of B2 ... Is transmitted to the output amplifier 206 via the switching transistors SWa, SWb ... Then, the vertical scanning circuit (V-
When the selection line SEL-3 is driven under the control of (SCAN), the switching transistor of the infrared sensor is turned on and at the same time the switching transistor for resetting of the visible light sensor is turned on, and the initial condition is reset again. The electrons excited by the light incident on the depletion layer continue to be accumulated until the next SEL-2 is driven. Similarly, in the electronic device of the present embodiment, each cell A3, B is controlled by the control of the vertical scanning circuit (V-SCAN) and the horizontal scanning circuit (H-SCAN).
3 ... Data Da3, Db3 ..., Each cell A4, B
The data Da4, Db4 ... of 4 ...
Are sequentially output from.

Then, it corresponds to the output voltage corresponding to the input of infrared rays in the cell in which the bolometer 201 of the infrared sensor IRS is arranged and the input of visible light in the cell in which the photodiode 301 of the visible light sensor VLS is arranged. Two-dimensional information about the detection target is obtained from the output voltage.

11A to 11F are perspective views showing the manufacturing steps of the electronic device having the cell array of this embodiment.

In the steps shown in FIGS. 11A to 11E, the same processes as the steps shown in FIGS. 7A to 7E in the first embodiment are performed. After that, in the step shown in FIG. 11F, the cap body wafer is divided into each cap body at the cut portion 152 of the cap body wafer 150. Then,
Of the cap bodies, the cap body for the visible light sensor does not adhere to the main body substrate 100, and is exposed on the main body substrate 100, the infrared sensor IRS covered by the infrared sensor IRS cap body 140, and the main body substrate 100. A cell array type device including the visible light sensor VLS is obtained.

Here, in the division shown in FIG. 11 (f), the thickness of the remaining portion in the cut portion 152 may be set so as to be naturally performed when a crimping force for joining is applied. Alternatively, a pressing force for splitting may be separately applied to the cut portion 152 after the joining by the above is completed.

Note that in FIGS. 11A to 11F,
7A to 7F are basically similar to the structures of the electronic devices, and thus, the same reference numerals are given, the cells in the discrete device and the cells in the integrated device are different from each other. Generally, the size is significantly different.

An electronic device having a vacuum dome having a dimension of a diameter (or one side) of several hundreds μm or less and a height of several hundreds μm or less could not be realized by the conventional technique, but according to the present embodiment. It has become possible to form such electronic devices. In this case, the wall thickness of the tubular portion of the cap body is several tens of μm or less, and the thickness of the ceiling portion is several hundreds of μm or less. In particular,
A vacuum dome having dimensions of several tens of μm or less in diameter (or one side) and several μm or less in depth can be called a “μ vacuum dome”. Further, the technique for forming such a vacuum dome requires joining of annular films having a thickness of submicron, and thus can be referred to as a "nano-junction μ vacuum dome".

In the case of a sensor having a cell array,
The main body substrate 100 includes a bolometer, a photodiode,
Wirings, electric circuits, and the like that connect the cells to each other are provided, but they are not shown in FIGS. 11A to 11F. Furthermore, since a plurality of sensors having a cell array are generally formed on one wafer, after the step shown in FIG.
Is diced to divide the chip into chips.

According to this embodiment, since the cells can be individually covered with the cap body, the infrared sensor IRS that needs to be sealed in a reduced pressure atmosphere in order to enhance the sensitivity on the same cell array is covered with the cap body. It is possible to cover and open the visible light sensor VLS, which requires the incidence of light. As a result, it becomes possible to design an electronic device in which the infrared sensor IRS and the visible light sensor VLS are mounted on the same cell array, which was difficult with the conventional method of covering the entire cell array with one cap body. Further, according to this embodiment, the following effects can be obtained.

First, in the conventional case where a large area including the entire cell array is covered with one cap body,
At the time of bonding for pressure bonding, a large pressure bonding force may be locally applied to the bonding portion, which may cause breakage of the bonding portion or cracking of the substrate. On the other hand, when the cap body is bonded to each cell individually as in the present embodiment, as shown in FIG. 11, the cut portion 152 is formed in the cap body wafer 150.
By providing the above, it is possible to equalize the stress applied to each joint during joining by pressure bonding. At that time, the cap body wafer may be naturally divided at the cut portion by the pressure force of bonding. That is, since it is possible to prevent an excessive stress from being locally generated, it is possible to improve the reliability at the time of joining, the subsequent steps, or the actual use.

Secondly, in the case where the entire cell array is enclosed by a single cap body as in the conventional sensor, if the joint failure occurs in a part of the joint portion, the entire cell array becomes defective, and the repair is performed. Is almost impossible to apply. On the other hand, according to the present embodiment, in an electronic device in which a large number of cells in which elements such as sensors are arranged are provided in an array, a cap body for vacuum sealing is attached to each cell, Even when the bonded portion of the cell is not maintained in a normal vacuum state due to defective bonding, it is possible to remedy the defect by taking measures such as utilizing the information of the cell adjacent to the cell.

Thirdly, as in the prior art, in the structure in which a large area including the entire cell array is covered with one cap body, when the cell array area is particularly large or the window portion of the cap body is thin. However, the pressure difference between the outside atmosphere and the depressurized atmosphere in the cap body may cause bending of the window portion, which may cause cracking of the window portion or contact between the window portion and the cell. On the other hand, in the present embodiment, such a problem does not occur because the cap body having a small area is provided for each cell. Therefore, it is possible to reduce the thickness of the window portion to increase the infrared ray detection sensitivity and to downsize the device.

In each of the above embodiments, the upper surface of each transistor included in each visible light sensor VLS is A
covered with a film of light-shielding material such as l or W,
The source / drain regions of each transistor are shielded from light.

(Third Embodiment) FIGS. 12A to 12C.
Are a structure of a camera according to the third embodiment of the present invention, a human detection state by a vehicle equipped with the camera,
9A and 9B are diagrams illustrating an image formation state.

As shown in FIG. 12A, in the camera 310 of this embodiment, a protective transparent plate 302 and a pair of reflecting mirrors 303 and 304 as an optical system are provided in a casing 308.
And a detection device 305 arranged in a cell array having an infrared sensor and a visible light sensor, and an image processing unit 306. Light rays are incident on this camera from a wide angle of view.

First, the detection of light by the camera will be described with reference to FIG. The light beam passes through the protective transparent plate 302, is reflected by the reflecting mirror 303 and the reflecting mirror 304, and then forms an image on the detection device 305 in which the infrared sensor IRS and the visible light sensor are arranged.

Then, as shown in the first and second embodiments, infrared rays and visible rays of the rays are converted into electric signals by the infrared sensor and the visible light sensor, respectively, and then the electric signals are converted into electric signals. Sent to the image processing unit 306,
It is output as a video signal.

Next, the state of detecting a person by the above-mentioned camera mounted on the vehicle will be described with reference to FIGS. 12 (b) and 12 (c).

As shown in FIG. 12 (b), the camera 310 of this embodiment is installed at the tip of the vehicle body (for example, inside the front grill, outside the headlight) where the front of the vehicle 320 can be photographed. 330 near 300m in front of
The case of detecting is described. Person 330 who is the subject
Therefore, the infrared rays emitted from the inside of the human body due to the body temperature of the person 330 and the light reflected from the surrounding environment are incident on the camera 310. Infrared rays caused by body temperature and visible light reflected by the skin are emitted from the face, hands, and the like, of the body surface of the person 330, where the skin is exposed. On the other hand, the infrared rays from the inside of the body are absorbed by the clothes from the portion where the skin is covered with the clothes and not exposed, and the visible light mainly reflected by the clothes reaches the camera. The light emitted from the person 330 is the camera 31.
When incident on 0, it is detected as described in the second embodiment, and a screen 34 for reproducing an image in the visual field range of the camera 310 is displayed.
At 0, the image is as shown in FIG. At this time, the image by the infrared sensor appears mainly as a clear pattern 341a on the screen, and the image by the visible light sensor also appears as a pattern 341b. Visible light entering the camera from a position hundreds of meters away from the headlight of a car in the dark, or from a position that cannot be captured by the headlight, is attenuated in intensity and decreases in brightness, but infrared rays have a longer wavelength than visible light. Therefore, it is difficult to attenuate and forms a clear image of the subject at the above position. In other words, the image obtained from the data signal from the infrared sensor and the image obtained from the data signal from the visible light sensor are combined to obtain one image that can determine whether the object is a living thing or an inanimate object. . In particular, a clear image of a person or an animal can be obtained even when the background is dark at night or when the background is bright like a snow scene.

The effects obtained by the camera of this embodiment will be described below. In the camera of this embodiment, as described in the second embodiment, the infrared sensor and the visible light sensor are arranged adjacent to each other on the same substrate,
The position where the infrared sensor is arranged is very close to the position where the visible light sensor is arranged. Therefore, the optical axis difference between the optical axis of the infrared sensor and the optical axis of the visible light sensor becomes small, and the visual field ranges of the respective cameras substantially match. As a result, when processing the data of the red and visible rays captured by the camera into one image, the deviation between the image position based on the infrared sensor data and the image position based on the visible light sensor data is almost unknown. Can be suppressed.

As described above, the camera of this embodiment can accurately capture images and positions of a person or an animal present in the field of view of the camera at a relatively long distance. Therefore,
When the presence of a person or an animal is required to be detected as soon as possible, such as a camera mounted on a vehicle, the camera of the present invention can be used to exert a remarkable effect.

(Other Embodiments) In each of the above embodiments, the connection between the bolometer forming the infrared sensor held in the reduced pressure atmosphere and the switching transistor has been described, but the present invention is not limited to this embodiment. Not something.

In each of the above-mentioned embodiments, only the cap body is provided with the hollow portion and the closed loop-shaped tubular portion surrounding the hollow portion. However, the present invention is not limited to this embodiment, and the cap is not limited thereto. Both the body and the main body substrate may have a hollow portion and a closed-loop cylindrical portion surrounding the hollow portion. Further, only the main body substrate may have a concave portion which becomes a hollow portion and a closed-loop cylindrical portion which surrounds the concave portion. In that case, the cap body may be flat.

Further, regarding the shape of the cylindrical portion surrounding the hollow portion,
It may have a cylindrical shape or a polygonal cylindrical shape such as a square cylindrical shape.
However, in order to maintain the cavity in a reduced pressure atmosphere, it is necessary to have a closed loop annular structure.

Further, it is also possible to use a flat main body substrate provided with only concave portions and no cylindrical portion. In that case, the cap substrate may be flat or may have a recess.

Further, it is also possible to use a flat cap substrate having only a concave portion and no cylindrical portion. In that case, the main body substrate may be flat or may have a recess.

Further, in each of the above-described embodiments, it is assumed that the cavity enclosed by the cap body is a vacuum dome. In that case, considering the easiness of joining the annular film by pressure bonding during the manufacturing process, the pressure inside the cavity is
Preferably 10 ^-2 Pa to 10 ^-4 about Pa but, 10 ^-4 Pa
Bonding in a vacuum atmosphere reaching 10 ⁻⁷ Pa below is also possible.

Further, in each of the above embodiments, the surface of the cap body may be provided with a lens function such as a Fresnel lens.

[0145]

According to the present invention, in the infrared sensor cell and the visible light sensor provided on the same substrate, the infrared sensor cell is sealed in a reduced pressure atmosphere with a cap body. This makes it possible to provide a highly reliable electronic device suitable for both discrete type and integrated type structures, a manufacturing method thereof, and a camera using this electronic device, while utilizing the existing electronic device manufacturing process. be able to.

[Brief description of drawings]

1A to 1D are sectional views schematically showing an example of a basic structure of an electronic device of the present invention.

2A to 2D are cross-sectional views schematically showing a structural example of a bonding portion for holding a vacuum of the electronic device of the present invention.

3A and 3B are, respectively, a plan view and a cross-sectional view taken along line IIIa-IIIa and line IIIb-IIIb showing an example of an electrical connection structure suitable for an electronic device of the present invention.

4A and 4B are a cross-sectional view and an electric circuit diagram of the infrared sensor according to the first embodiment of the present invention,
(C) is an electric circuit diagram of the visible light sensor according to the first embodiment of the present invention.

5A to 5F are cross-sectional views showing a manufacturing process of the infrared sensor according to the first embodiment of the present invention.

6A to 6E are plan views showing a process of forming a bolometer and its peripheral region.

7A to 7F are cross-sectional views showing a method of forming a cap body used in the electronic device of the first embodiment.

FIG. 8 is a sectional view schematically showing the configuration of an apparatus used for crimping.

FIG. 9 is a perspective view for explaining a configuration of an electronic device according to a second embodiment of the present invention.

FIG. 10 is a timing chart showing a method of controlling the electronic device according to the second embodiment.

11A to 11F are perspective views showing a manufacturing process of an electronic device having the cell array of the second embodiment.

12A to 12C are diagrams showing a structure of a camera of a third embodiment, a detection state of a vehicle equipped with the camera, and an image formation state.

13A to 13C are diagrams showing a structure of a conventional camera, a detection state of a vehicle equipped with the camera, and an image formation state.

[Explanation of symbols]

10 Main board 11 cell area 12 annular membrane 20 cap body 21 board part 22 Tube 23 Cavity 24 Ge layer 25 Si layer 26 annular membrane 27 grid pattern 30 switching transistors 31 Gate electrode 32 source electrode 33 drain electrode 35 Impurity diffusion layer 40 elements 41 Interlayer insulation film 42 passivation film 51 wiring 70 PN diode 71 Transistor for amplification 72 switching transistor 73 Switching transistor 78 Gate electrode 79 Source area 80 drain region 100 main board 110 Si substrate 111 resistor 112 Silicon nitride film 113 Silicon oxide film 116 BPSG film 117 passivation film 118 annular membrane 119 cavity 120 resistance element (bolometer) 130 switching transistor 131 Source area 132 drain region 133 gate electrode 140 cap body 141 board part 142 Tube 143 cavity 144 annular membrane Wafer for 150 caps 151 Al film 152 Notch 191 PN diode 192 Transistor for amplification 193 switching transistor 194 Switching transistor 195 wiring 196 wiring 197 wiring 198 wiring 302 Protective transparent plate 303 Reflector 304 reflector 305 Detection device 306 Image signal processing unit 308 casing 310 camera 320 vehicles 330 people 340 screen 341a image 341b image

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiko Hashimoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Michio Okajima             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Shinichi Yamamoto             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 4M118 AB01 BA06 CA05 CB01 CB12                       FA05 FA06 GB11 HA24

Claims (17)

[Claims] 1. A main body having a first cell region in which an infrared sensor having at least one thermoelectric conversion element is arranged, and a second cell region in which a visible light sensor having at least one photoelectric conversion element is arranged. A substrate, a cavity portion provided in a portion of the first cell region where the thermoelectric conversion element is arranged, surrounded by the main body substrate and the cap body, and kept in a reduced pressure atmosphere; And an annular joint for holding the electronic device. 2. The electronic device according to claim 1, wherein the first annular film formed on the main body substrate and made of a bonding member surrounding the thermoelectric conversion element is formed on the cap body. A second annular film made of the bonding material described above, wherein the annular bonding portion is formed between the first and second annular films. 3. The electronic device according to claim 1, wherein the main body substrate is made of a semiconductor, and the infrared sensor and the external circuit on the main body substrate are provided in the main body substrate with the annular shape. An electronic device, which is electrically connected to each other via an impurity diffusion layer formed across the junction. 4. The electronic device according to any one of claims 1 to 3, wherein the cap body is provided with a concave portion that forms the hollow portion and a cylindrical portion that surrounds the concave portion. The electronic device, wherein the main body substrate is provided with an engaging portion that engages with the tubular portion. 5. The electronic device according to claim 1, wherein the cap body has a Si substrate and a band gap smaller than 1.1 eV provided on the Si substrate. And a semiconductor layer having the electronic device. 6. The electronic device according to any one of claims 1 to 5, wherein the thermoelectric conversion element is a bolometer. 7. The electronic device according to claim 1, wherein the thermoelectric conversion element is a PN diode. 8. The electronic device according to claim 1, wherein a plurality of the first and second cell regions are respectively arranged to form a cell array. An electronic device, wherein the cap body is provided for each cell region. 9. A plurality of first cell regions in which an infrared sensor having at least one thermoelectric conversion element is arranged, and a plurality of second cell regions in which a visible sensor having at least one photoelectric conversion element is arranged. A step (a) of preparing a main body substrate having: a step (b) of forming a cap substrate; and a step of forming a cap substrate between the first cell region of the main body substrate and the cap substrate in a reduced pressure atmosphere. A step (c) of forming an annular joint between the main body substrate and the cap substrate by applying a pressing force. In the steps (a) and (b), the main body substrate and the cap substrate A recess is formed in at least one of the cap substrates, and in the step (c), a small number of the recess is formed in a portion of the first cell region where the element is arranged. And to remain as a cavity even part is held in the reduced pressure atmosphere, a method for fabricating an electronic device, and forming the annular joint. 10. The method of manufacturing an electronic device according to claim 9, wherein in the step (a), a main body substrate having a plurality of first annular films made of a bonding member surrounding a cavity forming region is prepared, In the step (b), the cap substrate having a plurality of second annular films made of a bonding material surrounding the cavity forming region is prepared, and in the step (c), the first and second annular films are formed. A method for manufacturing an electronic device, characterized in that the annular joint is formed between the films. 11. The method of manufacturing an electronic device according to claim 10, wherein in the step (b), the second annular film is
A method for manufacturing an electronic device, which is also formed in a region surrounding the visible light sensor. 12. The method of manufacturing an electronic device according to claim 9, wherein before the step (c), the cap substrate is formed in a plurality of regions. A method of manufacturing an electronic device, further comprising the step of forming a partitioning slit. 13. The method for manufacturing an electronic device according to claim 9, wherein in the step (b), the cap substrate is provided with a recess surrounded by the second annular film, and the recess. A method of manufacturing an electronic device, comprising preparing a substrate for a cap having a plurality of cylindrical portions surrounding the. 14. The method for manufacturing an electronic device according to claim 9, wherein the step (c) is performed in a reduced pressure atmosphere having a pressure higher than 10 ⁻⁴ Pa. And a method for manufacturing an electronic device. 15. The method of manufacturing an electronic device according to claim 9, further comprising a step of dividing the semiconductor substrate into cells, after the step (c). A method for manufacturing a characteristic electronic device. 16. A camera comprising an electronic device provided with an infrared sensor and a visible light sensor, and an optical system for introducing infrared light and visible light from the outside into the electronic device. Is a main substrate having a first cell region in which the infrared sensor having at least one thermoelectric conversion element is arranged and a second cell region in which the visible light sensor having at least one photoelectric conversion element is arranged. And a cavity portion provided in a portion of the first cell region where the thermoelectric conversion element is arranged, surrounded by the main body substrate and the cap body and held in a reduced pressure atmosphere, and the cavity portion in a reduced pressure atmosphere. A camera having an annular joint for holding. 17. A vehicle equipped with a camera incorporating an electronic device provided with an infrared sensor and a visible light sensor, wherein the electronic device is provided with the infrared sensor having at least one thermoelectric conversion element. A main body substrate having one cell region and a second cell region in which the visible light sensor having at least one photoelectric conversion element is disposed; and a portion in which the thermoelectric conversion element in the first cell region is disposed. A vehicle provided with a hollow portion surrounded by the main body substrate and the cap body and held in a reduced pressure atmosphere, and an annular joint portion for holding the hollow portion in a reduced pressure atmosphere.