JP2019029752A - Wafer cap, far infrared ray sensor, far infrared ray detection device, and cap - Google Patents

Abstract

To provide a more inexpensive far infrared ray detection device, wafer cap, and package.SOLUTION: A wafer cap that can be integrally joined to a sensor wafer is formed of silicon and is formed by arranging a plurality of cap portions 11 of the same shape, and the cap portion 11 includes a main body layer 12 and a lens-shaped portion 14 formed on at least one surface of the main body layer 12 and having a convex Fresnel lens shape or a concave Fresnel lens shape. In addition, a package obtained by joining the wafer cap to the sensor wafer and performing dicing is provided in a far infrared ray detection device 1 as a far infrared ray sensor portion 10.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wafer cap, a far infrared sensor, a far infrared detection device, and a cap.

  A far-infrared detector that detects far-infrared rays emitted from an object (see, for example, Patent Document 1) can measure the temperature distribution of a target object in a non-contact manner, and basically does not require a light source. Therefore, in recent years, it has begun to spread in various fields such as security, in-vehicle, monitoring, and quality control in factories.

JP2011-149975A

In the far-infrared detector, a lens group including a plurality of lenses for collecting far-infrared rays is disposed on the far-infrared incident side (object side) of the far-infrared ray detecting element. This lens group is conventionally formed of germanium having a high far-infrared transmittance.
However, germanium is a very rare material, and lenses made of germanium are very expensive. Further, since a lens group is formed by combining a plurality of such lenses, there is a problem that the far-infrared sensor becomes very expensive and hinders its spread.
In Patent Document 1, improvement is made by selecting a material other than germanium, such as using a material in which an inorganic material atomized into an organic material is mixed as a lens material. However, heating of the lens is necessary. Therefore, it is desired to realize an inexpensive far-infrared detector having a simpler configuration.

  It is an object of the present invention to provide a far-infrared detecting device that is less expensive and to provide a wafer cap, a far-infrared sensor, and a cap that enable this.

The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.
A first invention is a wafer cap that can be integrally bonded to a sensor wafer (170), and is formed of silicon, and is formed by arranging a plurality of cap portions (11) having the same shape. A wafer cap (110) comprising a main body layer (12) and a lens-shaped portion (14) formed on at least one surface of the main body layer and having a convex Fresnel lens shape or a concave Fresnel lens shape.
According to a second aspect of the present invention, there is provided the wafer cap according to the first aspect, wherein a reflection suppressing layer (15) is formed on at least an outer surface when bonded to the sensor wafer. It is.
According to a third aspect of the invention, there is provided a sensor substrate portion (17) including a detection element (18) for detecting light in a far-infrared wavelength region, and covering at least the detection element of the sensor substrate portion and bonding to the sensor substrate portion. A far-infrared sensor comprising a cap part (11), wherein the cap part is made of silicon, and a lens layer formed on a body layer (12) and at least one surface of the body layer (14), wherein the lens-shaped portion has a convex Fresnel lens shape or a concave Fresnel lens shape, and is provided at a position corresponding to the detection element. .
A fourth invention is a far-infrared sensor according to the third invention, wherein a reflection suppressing layer (15) is formed on at least a surface on the far-infrared incident side of the cap portion. Infrared sensor (10).
According to a fifth aspect of the present invention, the far-infrared sensor (10) according to the third or fourth aspect and the far-infrared light incident side of the far-infrared sensor than the cap portion (11), and at least one lens A far-infrared detector (1) provided with an optical system (20) provided with (21), and a control part (31) which controls the drive of the far-infrared sensor.
The sixth invention comprises a main body layer (12) and a lens-shaped portion (14) which is a convex Fresnel lens shape or a concave Fresnel lens shape and is formed on at least one surface of the main body layer. A cap (11) which is bonded to a sensor substrate (17) including a detection element (18) for detecting light in the wavelength range of linear infrared rays and covers the detection element.

  It is an object of the present invention to provide a far-infrared detecting device that is less expensive and to provide a wafer cap, a far-infrared sensor, and a cap that enable this.

It is a figure explaining the far-infrared detector 1 of an embodiment. It is a figure explaining the far-infrared sensor part 10 of embodiment. It is a figure explaining another form of the cap part 11 of embodiment. It is a figure explaining the manufacturing method of the far-infrared sensor part 10 of an embodiment.

Embodiments of the present invention will be described below with reference to the drawings. In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
In this specification, terms that specify shape and geometric conditions, for example, terms such as parallel and orthogonal, are strictly meanings, have similar optical functions, and can be regarded as parallel and orthogonal It also includes a state having an error of.
In addition, the numerical values such as the dimensions of the respective members and the material names described in the present specification are examples of the embodiment, and are not limited thereto, and may be appropriately selected and used.

(Embodiment)
FIG. 1 is a diagram illustrating a far-infrared detector 1 according to an embodiment.
The far-infrared detector 1 of the present embodiment includes a lens unit 20, a shutter unit 25, a control unit 31, a processing unit 32, a far-infrared sensor unit 10, and the like. In FIG. 1, for easy understanding, a Z axis parallel to the optical axis O direction is shown. In this Z axis, the object side is the + Z side, and the far infrared sensor unit 10 side is the -Z side.

The lens unit 20 is provided in an opening of a housing (not shown) of the far-infrared detector 1, and far-infrared rays emitted from the object are incident on the lens unit.
The lens unit 20 is an optical system that includes at least one lens 21 and has a function of collecting far-infrared rays, and is provided closer to the far-infrared incident side (+ Z side) than the far-infrared sensor unit 10. In FIG. 1, the lens part 20 provided with the two lenses 21 is shown as an example. The shape of each lens 21 and the combination thereof may be appropriately selected according to the desired optical performance of the lens unit 20. The lens 21 may be a Fresnel lens shape.
The lens 21 used in the lens unit 20 is formed of a material that transmits far infrared rays (particularly, far infrared rays having a wavelength range of 8 to 12 μm) such as germanium, chalcogenide glass, silicon, zinc selenide, and zinc sulfide.

The shutter unit 25 is disposed between the lens unit 20 and the far infrared sensor unit 10 along the optical axis O direction. This shutter unit 25 is a device that opens only during the exposure time of the detection element 18 of the far-infrared sensor unit 10 to be described later and passes far-infrared rays to the far-infrared sensor unit 10 side, and closes and blocks far-infrared rays at other times. . FIG. 1 shows a state where the shutter unit 25 is open, and a broken line shown in FIG. 1 shows a state where the shutter unit 25 is closed. In the present embodiment, the far-infrared detection device 1 has been described as including a mechanical shutter having a mechanical structure as the shutter unit 25. However, the present invention is not limited thereto, and the far-infrared detection device 1 does not have a mechanical structure. It is good also as a form provided with what is called an electronic shutter.
Further, the far-infrared detector 1 may include a diaphragm or the like between the lens unit 20 and the shutter unit 25 according to desired optical performance or the like.

The control unit 31 is electrically connected to the far infrared sensor unit 10 and is a control circuit that controls driving of the far infrared sensor unit 10. The control unit 31 is connected to a drive power supply (not shown).
The processing unit 32 is a processing circuit that is electrically joined to the far-infrared sensor unit 10 and performs processing such as imaging using an output signal from the far-infrared sensor unit 10. The processing unit 32 includes an output unit (not shown) and can output a signal or the like subjected to image processing to the outside of the far-infrared detector 1.
The far-infrared detector 1 is not limited to the above, and may be configured to further include a storage unit, a display unit, and the like (not shown).

FIG. 2 is a diagram illustrating the far-infrared sensor unit 10 of the present embodiment. In FIG. 2, the cross section parallel to the optical axis O direction of the far-infrared sensor part 10 is shown typically.
The far-infrared sensor unit 10 is a plate-like member having a rectangular shape in plan view. The far-infrared sensor unit 10 includes a sensor substrate 17 and a cap unit 11 located on the + Z side (far-infrared incident side, object side) of the sensor substrate 17.
The far-infrared sensor unit 10 is a so-called package formed by a wafer level package (WLP) in which the sensor substrate 17 and the cap unit 11 are bonded in a wafer state and then separated into individual pieces.

The sensor substrate 17 is a plate-like member having a rectangular shape in plan view, and is formed of a semiconductor such as silicon, and a wiring or the like (not shown) is formed on the surface thereof. Moreover, this wiring is electrically connected with the control part 31 and the process part 32 suitably.
The detection element 18 is an element that receives light in the far-infrared region (far-infrared ray) and converts it into an electrical signal. The detection element 18 of this embodiment has light receiving sensitivity with respect to light in a far infrared wavelength region (particularly, a wavelength region of about 8 to 12 μm). As such a detection element 18, a microbolometer, a thermopile, a pyroelectric element, etc. are used, for example.
The detection element 18 is disposed on the + Z side (incident side) of the sensor substrate 17 and is electrically connected to a wiring (not shown) provided on the sensor substrate 17.
An IC circuit (not shown) that performs signal processing on the signal output from the detection element 18 and outputs the signal to the processing unit 32 is provided on the sensor substrate 17 and is detected via the wiring on the sensor substrate 17. It may be configured to be electrically connected to the element 18.

The cap portion 11 has the same rectangular shape as the sensor substrate 17 when viewed from the optical axis O direction, sufficiently covers the sensor substrate 17, and is integrally joined to the sensor substrate 17. The cap unit 11 has a function of protecting the detection element 18 provided on the sensor substrate 17 and wiring.
The cap portion 11 is made of silicon, and has a main body layer 12, a lens-shaped portion 14 formed on at least one surface of the main body layer 12, and a protruding portion protruding from the main body layer 12 toward the sensor substrate 17 (−Z side). 13 etc.

The lens shape portion 14 has a convex Fresnel lens shape or a concave Fresnel lens shape, and is formed in a region corresponding to the detection element 18 when the far infrared sensor unit 10 is viewed from the optical axis O direction. Further, the lens shape portion 14 is provided so that the far infrared rays transmitted therethrough are focused on the light receiving surface of the detection element 18.
FIG. 2 shows an example in which the lens shape portion 14 has a convex Fresnel lens shape and is formed on the + Z side (incident side) surface of the main body layer 12 as an example. However, the lens shape portion 14 may have a concave Fresnel lens shape according to the optical performance of the lens portion 20.

The protruding portion 13 is formed in a region (region S2 shown in FIG. 2) which is a peripheral portion of the region where the lens-shaped portion 14 is provided (region S1 shown in FIG. 2), and toward the sensor substrate 17 side (−Z side). Projects at a predetermined height.
A bonding layer 16 is provided at the end of the protruding portion 13 on the sensor substrate 17 side, and the sensor substrate 17 and the cap portion 11 are integrally bonded by the bonding layer 16. The bonding layer 16 is made of a metal such as gold (Au).
The height of the protruding portion 13 (the protruding height from the main body layer 12) can be set according to the focal length of the lens-shaped portion 14. Further, by providing the protruding portion 13, a space 19 is formed between the detection element 18 and the cap portion 11. The space 19 is a vacuum in this embodiment, but may be appropriately filled with a gas such as air.

Reflected on the surface on the + Z side (incident side, object side) and the surface on the −Z side (exit side, sensor substrate 17 side) (particularly the region corresponding to the region S1) of the main body layer 12 of the cap part 11. A suppression layer (AR layer) 15 is formed. As shown in FIG. 2, the reflection suppression layer 15 is also formed on the surface of the unit lens that forms the Fresnel lens of the lens shape portion 14.
The reflection suppressing layer 15 is formed by coating a material having a reflection suppressing function, for example, diamond-like carbon (DLC) with a predetermined film thickness.
By providing such a reflection suppressing layer 15, the transmittance of far infrared rays can be improved even in the case of the silicon lens-shaped portion 14 having a far infrared transmittance lower than that of germanium or the like.

As described above, in the far-infrared sensor unit 10 of the present embodiment, the cap unit 11 that has been conventionally used as a member for protecting the sensor substrate 17 includes the lens-shaped unit 14 and is transmitted through the lens-shaped unit 14. The far infrared rays are focused on the light receiving surface of the detection element 18. Therefore, since the lens shape portion 14 also functions as an optical system for condensing the detection element 18, the number of lenses 21 of the lens portion 20 can be reduced.
A lens 21 using a rare material such as germanium is used as the lens unit 20 of the far-infrared detector 1, but such a lens 21 is reduced, and a cheaper silicon lens is conventionally used. By forming in the part 11, the far-infrared detector 1 can be reduced in size and weight, and the production cost can be reduced.
In a general far-infrared detector or the like, the lens 21 of the lens unit 20 is formed of germanium having a high transmittance of far-infrared rays (particularly, a wavelength of 8 to 12 μm). In general, silicon tends to have a far-infrared transmittance lower than that of germanium. However, as described above, when the lens shape of the lens shape portion 14 is a Fresnel lens shape, the thickness of the lens shape portion 14 can be reduced, and a sufficient transmittance can be secured.

In FIG. 2, as an example, the lens shape portion 14 is formed on the + Z side (incident side) of the main body layer 12 of the cap portion 11, but is not limited thereto.
FIG. 3 is a diagram illustrating another form of the cap portion 11 of the present embodiment.
As shown in FIG. 3A, the lens-shaped portion 14 may be provided on the surface of the main body layer 12 on the −Z side (sensor substrate 17 side) in the region S <b> 1 of the cap portion 11.
Further, as shown in FIG. 3B, the lens-shaped portion 14 may be provided on both surfaces (+ Z side and −Z side surfaces) of the main body layer 12 in the region S <b> 1 of the cap portion 11.

  The lens shape portion 14 is not limited to the convex Fresnel lens shape, and may be a concave Fresnel lens shape. For example, as shown in FIG. 3B, the lens shape portion 14 is formed on both surfaces of the main body layer 12. The lens shape portion 14 on one surface may be a convex Fresnel lens shape, and the lens shape portion 14 on the other surface may be a concave Fresnel lens shape. Although not shown, both surfaces are convex Fresnel lens shapes or concave Fresnel lens shapes. It is good also as a shape. The Fresnel lens shape type (concave or convex) formed as the lens shape portion 14, the surface of the main body layer 12 on which the lens shape portion 14 is provided, etc. are appropriately determined according to the optical characteristics of the lens portion 20. May be set.

Next, the manufacturing method of the far-infrared sensor part 10 of this embodiment is demonstrated.
FIG. 4 is a diagram for explaining a manufacturing method of the far-infrared sensor unit 10 of the present embodiment. 4B to 4E show a part of the silicon wafer 110 and the sensor wafer 170 (area corresponding to one package) in an enlarged manner.
As shown in FIG. 4A, a silicon wafer 110 is prepared.
A resist is applied to one surface 110b of the silicon wafer 110, a predetermined mask pattern is provided, and exposure and development are performed. Thereafter, dry etching is performed to form the protruding portion 13 on one surface 110b of the silicon wafer 110 as shown in FIG.
Next, after polishing the surface 110a of the silicon wafer 110 opposite to the surface 110b on which the protrusions 13 are formed, the thickness of the silicon wafer 110 (main body layer 12) is reduced to a predetermined value, and then FIG. ), The lens-shaped portion 14 is formed by etching.

Next, as shown in FIG. 4 (d), diamond-like carbon (DLC) is sputtered or deposited on regions 110a and 110b of the silicon wafer 110 corresponding to the region S1, and CVD (Chemical Vapor Deposition) is performed. The antireflection layer 15 is formed by phase growth) or the like. Thus, the silicon wafer 110 is formed in a state where the plurality of cap portions 11 are arranged.
Next, as shown in FIG. 4E, a sensor wafer 170 is prepared, a predetermined wiring is formed, and the detection element 18 is further arranged and electrically connected to the wiring.
Then, a bonding layer 16 is formed on the end of the protruding portion 13 by sputtering, vapor deposition, or the like using gold (Au), copper (Cu), aluminum (Al), etc. As shown in FIG. And the sensor wafer 170 are aligned and bonded. Then, by dicing (dividing into pieces), the far-infrared sensor unit 10 (package) is completed as shown in FIG.

In addition, when forming the lens shape part 14 in the surface which becomes the -Z side (sensor substrate 17 side) of the main body layer 12, when forming the protrusion part 13 by dry etching, the lens shape part 14 is formed simultaneously. It is possible.
The far-infrared sensor device 10 formed as described above is disposed at a predetermined position in the far-infrared detector 1 and a control circuit or the like is connected to complete the far-infrared detector 1.

  According to the present embodiment, by forming the lens shape portion 14 in the cap portion 11 formed of silicon that is less expensive than germanium, the number of lenses 21 constituting the lens portion 20 can be reduced. It is possible to provide a far-infrared detector 1 that is inexpensive and has sufficient optical performance. Further, since the number of lenses 21 constituting the lens unit 20 can be reduced, the far-infrared detector 1 can be reduced in size, thickness, and weight.

(Deformation)
The present invention is not limited to the embodiment described above, and various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In the embodiment, the far-infrared sensor unit 10 has been described as being used in the far-infrared detector 1, but the present invention is not limited thereto, and may be used in, for example, a far-infrared camera.

(2) In the embodiment, the far-infrared detector 1 includes a drive unit (not shown), and this drive unit holds each lens 21 of the lens unit 20 and can move each lens 21 along the optical axis O direction. It is good also as a form which is. In the case of such a configuration, the distance between the lenses 21 and the distance between the lens 21 and the far-infrared sensor unit 10 can be appropriately set as appropriate.

  In addition, although this embodiment and modification can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited to the above-described embodiment and the like.

DESCRIPTION OF SYMBOLS 1 Far-infrared detector 10 Far-infrared sensor part 11 Cap part 12 Main body layer 13 Protrusion part 14 Lens shape part 15 Antireflection layer 16 Bonding layer 17 Sensor substrate 18 Detection element

Claims (6)

A wafer cap that can be integrally bonded to a sensor wafer,
Formed by silicon,
A plurality of cap parts having the same shape are arranged and formed.
The cap part is
The body layer,
Formed on at least one surface of the main body layer, a lens-shaped portion that is a convex Fresnel lens shape or a concave Fresnel lens shape;
A wafer cap comprising: The wafer cap according to claim 1,
A reflection suppressing layer is formed on the surface which is at the outer side at least when bonded to the sensor wafer,
A wafer cap characterized by the following. A sensor substrate having a detection element for detecting light in the far-infrared wavelength region;
A cap portion that covers at least the detection element of the sensor substrate portion and is joined to the sensor substrate portion;
A far infrared sensor comprising:
The cap part is
Formed by silicon,
The body layer,
A lens-shaped portion formed on at least one surface of the main body layer;
With
The lens shape portion is a convex Fresnel lens shape or a concave Fresnel lens shape, and is provided at a position corresponding to the detection element;
Far infrared sensor characterized by. The far-infrared sensor according to claim 3,
A reflection suppressing layer is formed on at least the far infrared light incident side of the cap portion;
Far infrared sensor characterized by. The far-infrared sensor according to claim 3 or claim 4,
An optical system that is disposed on the far-infrared incident side of the cap portion of the far-infrared sensor and includes at least one lens;
A control unit for controlling driving of the far-infrared sensor;
A far-infrared detector comprising: The body layer,
A convex Fresnel lens shape or a concave Fresnel lens shape, and a lens shape portion formed on at least one surface of the main body layer;
With
A cap that is bonded to a sensor substrate including a detection element that detects light in the far-infrared infrared wavelength region and covers the detection element.

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