JP2019039712A - Infrared detector and method for manufacturing the same, imaging device, imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a dark current flowing on a side surface of a light receiving layer and improve the performance of an infrared detector. SOLUTION: An infrared detector is provided on a first electrode layer 2 provided above a (111) B substrate 1, and a first insulating film 3 provided on the first electrode layer and having a hexagonal columnar opening 3X. A hexagonal columnar light receiving layer 4 provided on the first electrode layer and at the hexagonal columnar opening and having a side surface in contact with the first insulating film, a second electrode layer 5 provided on the light receiving layer, and a second electrode layer. The second insulating film 6 that covers the two electrode layers is provided. [Selection diagram] Fig. 1

Description

  The present invention relates to an infrared detector, a method for manufacturing the same, an imaging device, and an imaging system.

  In an infrared detector, a lower contact layer, a light absorption layer, and an upper contact layer are generally stacked on a substrate, separated by etching into a quadrangular prism shape, and a protective film is generally formed to cover the whole.

JP 2014-169876 A

By the way, in the infrared detector, reduction of dark current is a problem.
In particular, in order to improve the performance of an infrared detector, it is necessary to reduce the dark current component flowing on the side wall surface (side surface) of the light absorption layer (light receiving layer).
It is an object of the present invention to reduce the dark current flowing through the side surface of the light receiving layer and improve the performance of the infrared detector.

In one aspect, the infrared detector includes a first electrode layer provided above the (111) B substrate, a first insulating film provided on the first electrode layer and having a hexagonal columnar opening, A hexagonal column-shaped light receiving layer provided on the one electrode layer and in the hexagonal column-shaped opening and having a side surface in contact with the first insulating film, a second electrode layer provided on the light receiving layer, and the second electrode layer are covered. A second insulating film.
In one aspect, the imaging device includes an infrared detector array in which a plurality of pixels are arranged on a plane with the above-described infrared detector as one pixel with the first insulating film interposed therebetween.

In one mode, an imaging system is provided with the above-mentioned imaging device and a control operation part connected to the imaging device.
In one aspect, a method of manufacturing an infrared detector includes a step of forming a first electrode layer above a (111) B substrate, and a first insulating film having a hexagonal columnar opening on the first electrode layer. Forming a hexagonal columnar light-receiving layer on the first electrode layer and in the hexagonal column-shaped opening so that the side surface is in contact with the first insulating film, and the second electrode on the light-receiving layer Forming a layer and forming a second insulating film so as to cover the second electrode layer.

  As one side surface, there is an effect that the dark current flowing on the side surface of the light receiving layer can be reduced and the performance of the infrared detector can be improved.

It is typical sectional drawing which shows the structural example of the infrared detector concerning this embodiment. It is a typical sectional view showing other examples of composition of an infrared detector concerning this embodiment. It is typical sectional drawing which shows the structure of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the specific example of the infrared detector concerning this embodiment. It is a typical sectional view showing the composition of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is typical sectional drawing for demonstrating the manufacturing method of the 1st modification of the infrared detector concerning this embodiment. It is a typical sectional view showing the composition of the 2nd modification of the infrared detector concerning this embodiment. It is a schematic diagram which shows the structural example of the image pick-up element concerning this embodiment. It is a typical sectional view showing an example of composition of an image sensor concerning this embodiment. It is a mimetic diagram showing the example of composition of the imaging system concerning this embodiment.

Hereinafter, an infrared detector according to an embodiment of the present invention, a manufacturing method thereof, an imaging device, and an imaging system will be described with reference to FIGS.
The infrared detector according to the present embodiment is an infrared detector that detects infrared rays. For example, a superlattice structure made of a narrow gap semiconductor such as InAs or GaSb, or a mixed crystal thereof, in an infrared absorption layer (light receiving layer). Or an infrared detector suitable for a type II superlattices (T2SL) type.

As shown in FIG. 1, the infrared detector according to the present embodiment includes a first electrode layer 2 provided above a (111) B substrate 1 and a first insulating film 3 provided on the first electrode layer 2. A light receiving layer 4 provided on the first electrode layer 2, a second electrode layer 5 provided on the light receiving layer 4, and a second insulating film 6 covering the second electrode layer 5.
The first electrode layer 2 is also referred to as a first contact layer or a lower electrode layer. The second electrode layer 5 is also referred to as a second contact layer or an upper electrode layer.

In particular, the first insulating film 3 has a hexagonal columnar opening 3X, and the hexagonal columnar light receiving layer 4 whose side surface is in contact with the first insulating film 3 is provided in the hexagonal columnar opening 3X (for example, (See FIG. 21).
Here, the hexagonal columnar opening 3 </ b> X is an opening having a hexagonal cross-sectional area along the surface of the (111) B substrate 1. The hexagonal columnar light receiving layer 4 is a light receiving layer having a hexagonal cross-sectional area in the direction along the surface of the (111) B substrate 1.

Thereby, the dark current can be reduced.
That is, first, the dark current component flowing through the side surface (side wall surface) of the light receiving layer 4 has a correlation with the ratio between the peripheral length P and the area A of the light receiving layer 4 (pixel), and is expressed by the following equation.
I _Surface ∝ P / A
For this reason, for the same cross-sectional area, the smaller the sum of the peripheral lengths, the smaller the dark current component flowing on the side wall surface of the light receiving layer 4.

Therefore, as described above, the peripheral length required to obtain the same cross-sectional area in the light-receiving layer 4 can be reduced by about 7% by making the cross-sectional shape of the light-receiving layer 4 not hexagonal but hexagonal. .
Thereby, the dark current component (surface leakage current) flowing on the side wall surface of the light receiving layer 4 can be reduced.
Further, as described above, by using the (111) B substrate 1 and the hexagonal columnar opening 3X provided in the first insulating film 3, the side surface is first insulated by film formation as will be described later. It is possible to form a hexagonal columnar light receiving layer 4 in contact with the film 3.

For this reason, it becomes unnecessary to form the light receiving layer 4 by etching, and it is possible to suppress damage due to etching on the side wall surface of the light receiving layer 4 and oxidation due to exposure to the atmosphere.
Thereby, the dark current component flowing on the side wall surface of the light receiving layer 4 can be reduced.
Here, the (111) B substrate 1 is a substrate having a (111) B surface index, that is, a substrate having a (111) B surface orientation.

In the present embodiment, the (111) B substrate 1 is made of any one of InAs, GaSb, GaAs, and InP.
The first electrode layer 2 and the second electrode layer 5 are provided so as to sandwich the light receiving layer 4. The first electrode layer 2, the light receiving layer 4, and the second electrode layer 5 are disposed above the (111) B substrate 1. Are stacked in order to form a semiconductor stacked body.

Here, the first electrode layer 2 is preferably made of InAs.
The second electrode layer 5 is preferably made of InAs or GaSb, or laminated.
The light-receiving layer 4 is a light absorption layer, and here is an infrared absorption layer that absorbs infrared rays to generate carriers.

In the present embodiment, the light-receiving layer 4 is made of any material of InAs, InSb, GaSb, and AlSb, or is made of a mixed crystal containing any two or more of InAs, InSb, GaSb, and AlSb, or InAs. , InSb, GaSb, and AlSb.
For example, the light-receiving layer 4 may be made of a superlattice structure made of a narrow gap semiconductor such as InAs or GaSb or a mixed crystal thereof. In addition, for example, by forming a superlattice structure on a GaSb substrate using a material such as GaSb, InAs, and AlSb having a lattice constant close to that of the GaSb substrate to form the light-receiving layer 4, mid-infrared (3 to 5 μm) Infrared rays in the far-infrared (8 to 12 μm) region can be detected, and application to the security field, for example, becomes possible.

The first insulating film 3 may be provided so as to cover at least the side surface of the light receiving layer 4.
Here, the first insulating film 3 and the second insulating film 6, _SiN, or consist of any of the materials SiO 2, SiON, or, _SiN, formed by laminating one or two or more kinds of SiO 2, SiON The first insulating film 3 is preferably made of SiN at least in a region in contact with the side surface of the light receiving layer 4.

In the present embodiment, the first electrode 7 is provided on the first electrode layer 2, and the second electrode 8 is provided on the second electrode layer 5.
Further, as shown in FIG. 2, the light receiving layer 4 may have a cross-sectional area in the direction along the surface of the (111) B substrate 1 that is smaller than that of the second electrode layer 5.
The infrared detector of the present embodiment configured as described above can be manufactured as follows.

  That is, in the manufacturing method of the infrared detector of the present embodiment, the step of forming the first electrode layer 2 above the (111) B substrate 1 and the hexagonal column-shaped opening 3X on the first electrode layer 2 are formed. A step of forming the first insulating film 3 and a step of forming the hexagonal columnar light-receiving layer 4 on the first electrode layer 2 and in the hexagonal columnar opening 3X so that the side surface is in contact with the first insulating film 3. And a step of forming the second electrode layer 5 on the light receiving layer 4 and a step of forming the second insulating film 6 so as to cover the second electrode layer 5 (see, for example, FIGS. 1 and 2).

In the present embodiment, after the step of forming the second insulating film 6 described above, a step of exposing the first electrode layer 2 and part of the second electrode layer 5 to form the first electrode 7 and the second electrode 8. (See, for example, FIGS. 1 and 2).
By the way, the reason for adopting the above-described configuration and manufacturing method is as follows.
In the infrared detector, a type II superlattices (T2SL) is expected as a next-generation material to be replaced with mercury cadmium telluride (MCT), and is actively studied.

In many cases, a superlattice structure is formed on a GaSb substrate using a material such as GaSb, InAs, or AlSb, which has a lattice constant close to that of the GaSb substrate, and is used as an infrared absorption layer (light receiving layer). 3-5 [mu] m), far infrared (8-12 [mu] m) infrared rays can be detected, and application to the security field, for example, is possible.
However, in the infrared detector using T2SL, reduction of dark current is a problem.

Here, the dark current I _d of the infrared detector is expressed by the following equation.
I _d = I _Bulk + I _Surface
Thus, the dark current _{I d} of the infrared detector is expressed by the sum of components _{I Surface} flowing sidewall surface of the light receiving layer and the bulk component _{I Bulk} flowing inside the light-receiving layer.
In order to improve the performance of the infrared detector, it is necessary to reduce the dark current component flowing on the side wall surface of the light receiving layer.

However, conventionally, by removing a part of the light receiving layer by etching or the like, the cross-sectional shape of the light receiving layer (pixel) is made to be a square shape.
In addition, products and impurities adhere to the side surface of the light-receiving layer due to etching, etc., or the side surface of the light-receiving layer is exposed to the atmosphere during the process, causing the surface to oxidize, which causes an increase in dark current. ing.

Although attempts have been made to reduce dark current by passivation of the side surfaces of the light receiving layer with an insulating film, an effective insulating film forming process has not been established.
Therefore, the above-described configuration and manufacturing method are employed.
Hereinafter, the infrared detector and the manufacturing method thereof according to the present embodiment will be described with reference to FIGS.

In this specific example, as shown in FIG. 3, the infrared detector has an n-type InAs first electrode layer 2A via a GaSb buffer layer 9 and an InAsSb etching stopper layer 10 above an n-type GaSb (111) B substrate 1A. Is provided.
In addition, a SiO ₂ first insulating film 3A having a hexagonal column-shaped opening 3X is provided on the n-type InAs first electrode layer 2A, and the n-type InAs first electrode layer 2A is formed on the n-type InAs first electrode layer 2A. The portion 3X includes a hexagonal columnar light receiving layer 4A made of a superlattice of InAs and GaSb so that the side surface is in contact with the SiO ₂ first insulating film 3A.

Then, a p-type GaSb / n-type InAs second electrode layer 5A is provided on the light-receiving layer 4A, and a SiO ₂ second insulating film 6A covering the p-type GaSb / n-type InAs second electrode layer 5A is provided.
Further, the first electrode 7 and the second electrode 8 are provided so as to be in contact with the surfaces of the n-type InAs first electrode layer 2A and the p-type GaSb / n-type InAs second electrode layer 5A, and the other surfaces are made of SiO 2 ₂ The first insulating film 3A and the SiO ₂ second insulating film 6A are covered.

The infrared detector having such a structure can be manufactured as follows.
Here, the semiconductor multilayer structure constituting the infrared detector is epitaxially grown on the n-type GaSb (111) B substrate 1A.
That is, the epitaxial growth layer includes a GaSb buffer layer 9, an InAsSb etching stopper layer 10, an n-type InAs first electrode layer 2A, a light-receiving layer 4A composed of a superlattice of InAs and GaSb, and a p-type GaSb / n-type InAs second electrode layer 5A. Consists of.

Specifically, each layer of the semiconductor multilayer structure constituting the infrared detector is formed by, for example, molecular beam epitaxy (MBE).
First, the n-type GaSb (111) B substrate 1A is introduced into the substrate introduction chamber of the MBE apparatus. Note that the n-type GaSb (111) B substrate 1A is degassed in the preparation chamber.
Next, it is transported to a growth chamber held in an ultrahigh vacuum.

The n-type GaSb (111) B substrate 1A transferred to the growth chamber is heated in an Sb atmosphere in order to remove the oxide film on the surface.
After the oxide film is removed in this way, in order to improve the flatness of the substrate surface, a GaSb buffer layer 9 is formed on the n-type GaSb (111) B substrate 1A as shown in FIG. Grow about 100 nm at about 500 ° C.

Next, as illustrated in FIG. 5, an InAsSb etching stopper layer 10 is grown on the GaSb buffer layer 9 by, for example, about 300 nm.
In this case, the mixed crystal composition of the InAsSb layer is preferably set so as to lattice match with GaSb. For example, InAs _0.91 Sb _0.09 .
Next, as illustrated in FIG. 5, for example, an n-type InAs first electrode layer 2 </ b> A having an Si-doped electron concentration of about 1 × 10 ¹⁸ cm ⁻³ is grown, for example, about 30 nm.

Next, as shown in FIGS. 6 and 7, a SiO ₂ first insulating film (SiO ₂ mask) 3A having hexagonal columnar openings 3X is formed.
That is, the substrate 1A on which the n-type InAs first electrode layer 2A has been formed is taken out of the MBE apparatus and, as shown in FIG. 6, for example, using a chemical vapor deposition (CVD) method, SiO ₂ For example, the film 3A is formed with a thickness of about 1000 nm.

Next, as shown in FIG. 7, for example, a template substrate provided with a SiO ₂ first insulating film 3A having hexagonal columnar openings 3X by performing electron beam lithography (EB) and etching with a chemical solution or the like. 11 is formed.
Next, this template substrate 11 is again introduced into the growth chamber of the MBE apparatus, and as shown in FIG. 8, a hexagonal columnar light receiving layer 4A made of a superlattice of InAs and GaSb is formed.

For example, the light receiving layer 4A is formed by stacking three types of superlattices having different carrier concentrations as follows.
That is, first, an n-type superlattice is formed.
Here, n-type InAs having an electron concentration of about 5 × 10 ¹⁷ cm ⁻³ is formed with about 2.2 nm, and undoped GaSb is formed with about 2 nm.

For example, when InAs is deposited, InAs can be formed only in the hexagonal columnar opening 3X of the SiO ₂ first insulating film 3A by alternately supplying In and As. In addition, since the (111) B substrate 1A is used, it can be formed in a hexagonal column shape so that the side surface is perpendicular to the substrate surface and the side surface is in contact with the SiO ₂ first insulating film 3A. GaSb is also formed in the same manner.

Note that an InSb film may be formed at the interface between InAs and GaSb so as to lattice match with the GaSb substrate.
Here, such film formation of InAs and GaSb is repeated until the thickness reaches, for example, about 200 nm.
Next, an i-type superlattice is formed.

Here, undoped InAs and GaSb are formed at about 2.2 nm and about 2 nm, respectively.
The film forming method may be the same as that for the n-type superlattice.
Here, such film formation of InAs and GaSb is repeated until the thickness becomes, for example, about 600 nm.

Next, a p-type superlattice is formed.
Here, about 2.2 nm of undoped InAs and about 2 nm of p-type GaSb having a hole concentration of about 5 × 10 ¹⁷ cm ⁻³ are formed.
The film forming method may be the same as that for the n-type superlattice.
Here, such film formation of InAs and GaSb is repeated until the thickness reaches, for example, about 200 nm.

Next, as shown in FIG. 9, a p-type GaSb / n-type InAs second electrode layer 5A is formed.
Here, about 100 nm of p-type GaSb having a hole concentration of about 1 × 10 ¹⁸ cm ⁻³ is formed, and then about 30 nm of n-type InAs having an electron concentration of about 1 × 10 ¹⁸ cm ⁻³ is formed. The film forming method may be the same as that for the n-type superlattice.
Here, the light receiving layer 4A is formed so as to have a film thickness comparable to the film thickness of the first insulating film 3A of the template substrate 11, and the second electrode layer 5A is formed on the light receiving layer 4A. The entire electrode layer 5A is located above the upper surface of the first insulating film 3A, but is not limited to this.

For example, the light receiving layer 4A is formed thinner than the thickness of the first insulating film 3A of the template substrate 11, the second electrode layer 5A is formed thereon, and part of the second electrode layer 5A is the first insulating film. It may be positioned above the upper surface of 3A.
Here, the hexagonal column-shaped second electrode layer 5A having the same cross-sectional area as the light-receiving layer 4A along the surface of the substrate 1A is formed on the hexagonal columnar light-receiving layer 4A. The hexagonal column-shaped second electrode layer 5A having a cross-sectional area in the direction along the surface of the substrate 1A larger than that of the light-receiving layer 4A may be formed on the hexagonal columnar light-receiving layer 4A. 2).

Next, as shown in FIG. 10, a SiO ₂ second insulating film 6A is formed so as to cover the p-type GaSb / n-type InAs second electrode layer 5A.
Next, as shown in FIG. 10, by etching using a mask, a part of the n-type InAs first electrode layer 2A and a part of the p-type GaSb / n-type InAs second electrode layer 5A are exposed. The SiO ₂ first insulating film 3A and the SiO ₂ second insulating film 6A are selectively etched to form a first electrode 7 and a second electrode 8 made of, for example, Ti / Pt / Au.

At this time, contamination and oxidation of the side surface of the light receiving layer 4A can be prevented by selectively etching so that the side surface of the light receiving layer 4A is not exposed.
In this way, an infrared detector can be manufactured.
According to the infrared detector configured as described above and manufactured in this way, the cross-sectional shape of the light receiving layer 4A (pixel) is a hexagon, and therefore is the same as that of a square having a general pixel shape. The pixel peripheral length becomes smaller with respect to the pixel area. For this reason, the dark current which flows through the side wall surface of the light receiving layer 4A can be reduced.

Further, since the light receiving layer 4A (pixel) can be formed in a columnar shape by film formation, a step of forming the light receiving layer 4A (pixel) by etching is not required, and at least damage caused by etching of the sidewall surface of the light receiving layer 4A. Oxidation due to exposure to the atmosphere. Thereby, the dark current component flowing on the side wall surface of the light receiving layer 4A can be reduced.
In addition, you may change suitably the structure of this example in the range with which an effect is acquired.

For example, in this specific example, the light receiving layer 4A is a superlattice of InAs and GaSb, but the thickness of each layer may be appropriately changed according to the absorption wavelength. The superlattice may be composed of any two or more of InAs, InSb, GaSb, and AlSb. In addition, the light receiving layer 4A may be made of these mixed crystals as long as the material responds to the infrared region. For example, InAs _1-a Sb _a (0 ≦ a ≦ 1) may be used.

The first electrode layer 2A is InAs, but may be GaSb.
However, InAs is preferable from the viewpoint of easy handling of the natural oxide film. That is, when etching is performed to form the first insulating film 3A having the hexagonal columnar opening 3X on the first electrode layer 2A, a natural oxide film is formed on the surface of the first electrode layer 2A. This increases the leakage current, but it is preferable to use InAs because a natural oxide film is difficult to form in InAs.

Further, before growing the light receiving layer 4A on the template substrate 11, after removing the natural oxide film on the surface of the first electrode layer 2A of the opening 3X of the template substrate 11, before forming the light receiving layer 4A, The same material as the first electrode layer 2A may be deposited to planarize the surface.
Further, the impurity to be doped is Si or Be, but other impurities may be used. For example, Te may be used as the n-type impurity.

In addition, although the semiconductor layered structure of the infrared detector is formed by the MBE method, for example, the MOCVD method or a method capable of producing another stacked structure may be used.
Moreover, although the structure of the infrared detector is a pin type, the i layer may be an n type or a p type.
Further, in the structure of the infrared detector, the etching stopper layer 10 may not be provided. Further, the substrate 1A and the buffer layer 9 may be removed.

By the way, in order to suppress the dark current, a barrier layer 12 may be provided between at least one of the light receiving layer 4 and the second electrode layer 5 and between the light receiving layer 4 and the first electrode layer 2 ( For example, see FIG.
For example, as shown in FIG. 11, a barrier layer 12 may be inserted between the light receiving layer 4B and the second electrode layer 5B. This is referred to as a first modification.

In this first modification, the infrared detector includes an n-type InAs first electrode layer 2A above an n-type InAs (111) B substrate 1B via an InAs buffer layer 9A.
In addition, a SiO ₂ first insulating film 3A having a hexagonal column-shaped opening 3X is provided on the n-type InAs first electrode layer 2A, and the n-type InAs first electrode layer 2A is formed on the n-type InAs first electrode layer 2A. The portion 3X is provided with a hexagonal columnar light-receiving layer 4B made of InAs so that the side surface is in contact with the SiO ₂ first insulating film 3A.

Then, the undoped AlAsSb barrier layer 12A and the n-type InAs second electrode layer 5B are provided on the light receiving layer 4B, and the SiO ₂ second insulating film 6A covering the undoped AlAsSb barrier layer 12A and the n-type InAs second electrode layer 5B is provided. Prepare.
In addition, the first electrode 7 and the second electrode 8 are provided so as to be in contact with the surfaces of the n-type InAs first electrode layer 2A and the n-type InAs second electrode layer 5B, and the other surfaces are made of SiO ₂ first insulation. The film 3A and the SiO ₂ second insulating film 6A are covered.

The infrared detector having such a structure can be manufactured as follows.
Here, the semiconductor multilayer structure constituting the infrared detector is epitaxially grown on the n-type InAs (111) B substrate 1B. That is, the epitaxial growth layer includes the InAs buffer layer 9A, the n-type InAs first electrode layer 2A, the light-receiving layer 4B made of InAs, the undoped AlAsSb barrier layer 12A, and the n-type InAs second electrode layer 5B.

Specifically, each layer of the semiconductor stacked structure constituting the infrared detector structure is formed by, for example, molecular beam epitaxy (MBE).
First, the n-type InAs (111) B substrate 1B is introduced into the substrate introduction chamber of the MBE apparatus. The n-type InAs (111) B substrate 1B is degassed in the preparation chamber.
Next, it is transported to a growth chamber held in an ultrahigh vacuum.

The n-type InAs (111) B substrate 1B transferred to the growth chamber is heated in an As atmosphere in order to remove the oxide film on the surface.
After removing the oxide film in this way, in order to improve the flatness of the substrate surface, as shown in FIG. 12, an InAs buffer layer 9A is formed on the n-type InAs (111) B substrate 1B, for example, at the substrate temperature. Grow about 100 nm at about 500 ° C.

Next, as shown in FIG. 13, an n-type InAs first electrode layer 2A having, for example, a Si-doped electron concentration of about 1 × 10 ¹⁸ cm ⁻³ is grown on the InAs buffer layer 9A, for example, about 300 nm.
Next, as shown in FIGS. 14 and 15, a SiO ₂ first insulating film 3A having a hexagonal columnar opening 3X is formed.

That is, the substrate 1B on which the n-type InAs first electrode layer 2A has been formed is taken out from the MBE apparatus and, as shown in FIG. 14, for example, using a chemical vapor deposition (CVD) method, SiO ₂ For example, the film 3A is formed with a thickness of about 1000 nm.
Next, as shown in FIG. 15, a template substrate including a SiO ₂ first insulating film 3A having hexagonal columnar openings 3X, for example, by performing electron beam lithography (EB) and etching with a chemical solution or the like. 11A is formed.

Next, this template substrate 11A is again introduced into the growth chamber of the MBE apparatus, and a hexagonal columnar light-receiving layer 4B made of InAs is formed as shown in FIG. Here, about 1000 nm of n-type InAs having an electron concentration of about 2 × 10 ¹⁶ cm ⁻³ doped with Si is formed.
In this case, for example, InAs can be formed only in the hexagonal columnar opening 3X of the SiO ₂ first insulating film 3A by alternately supplying In and As.

Further, since the (111) B substrate 1B is used, it can be formed in a hexagonal column shape so that the side surface is perpendicular to the substrate surface and the side surface is in contact with the SiO ₂ first insulating film 3A.
Next, as shown in FIG. 17, an undoped AlAsSb barrier layer 12A is formed. Here, an undoped AlAs _0.15 Sb _0.85 layer is formed to a thickness of about 100 nm. The film forming method may be the same as in the case of the light receiving layer 4B.

Next, as shown in FIG. 18, the n-type InAs second electrode layer 5B is formed. Here, n-type InAs having an electron concentration of about 1 × 10 ¹⁸ cm ⁻³ doped with Si is formed to about 100 nm. The film forming method may be the same as in the case of the light receiving layer 4B.
Here, the light receiving layer 4B is formed so as to have a film thickness comparable to the film thickness of the first insulating film 3A of the template substrate 11A, and the barrier layer 12A and the second electrode layer 5B are formed thereon. The barrier layer 12A and the second electrode layer 5B are all located above the upper surface of the first insulating film 3A, but the present invention is not limited to this.

For example, the light receiving layer 4B is formed thinner than the thickness of the first insulating film 3A of the template substrate 11A, the barrier layer 12A and the second electrode layer 5B are formed thereon, and a part of the second electrode layer 5B or Part of the second electrode layer 5B and the barrier layer 12A may be positioned above the upper surface of the first insulating film 3A.
Here, the hexagonal columnar barrier layer 12A and the second electrode layer 5B having the same cross-sectional area along the surface of the substrate 1B as the light receiving layer 4B are formed on the hexagonal columnar light receiving layer 4B. However, the present invention is not limited to this. On the hexagonal columnar light-receiving layer 4B, the hexagonal columnar barrier layer 12A and the second electrode layer 5B having a cross-sectional area in the direction along the surface of the substrate 1B larger than that of the light-receiving layer 4B. It may be formed.

Next, as shown in FIG. 19, the SiO ₂ second insulating film 6A is formed so as to cover the undoped AlAsSb barrier layer 12A and the n-type InAs second electrode layer 5B.
Next, the SiO ₂ first insulating film 3A and the SiO ₂ second electrode are exposed by etching using a mask so that a part of the n-type InAs first electrode layer 2A and a part of the n-type InAs second electrode layer 5B are exposed. 2 Insulating film 6A is selectively etched to form first electrode 7 and second electrode 8 made of, for example, Ti / Pt / Au.

In this way, an infrared detector can be manufactured.
In addition, you may change suitably the structure of this 1st modification in the range with which an effect is acquired.
For example, in the first modified example, the light receiving layer 4 is made of InAs, but is not limited thereto, and the light receiving layer 4 is made of any material of InAs, InSb, GaSb, and AlSb. Just do it. The light receiving layer 4 may be a superlattice composed of any two or more of InAs, InSb, GaSb, and AlSb. In addition, the light receiving layer 4 may be made of a mixed crystal of any material as long as it is a material that responds to the infrared region. For example, InAs _1-a Sb _a (0 ≦ a ≦ 1) may be used.

The impurity to be doped is Si, but it may be other than Si. For example, Te may be used as the n-type impurity.
In addition, although the semiconductor layered structure of the infrared detector is formed by the MBE method, for example, the MOCVD method or a method capable of producing another stacked structure may be used.
The structure of the infrared detector may be a pin type.

Further, an etching stopper layer may be inserted in the structure of the infrared detector. Further, the substrate 1B and the buffer layer 9A may be removed.
By the way, in the specific example and the first modification described above, the first insulating film 3 (3A) and the second insulating film 6 (6A) are SiO ₂ films, but the present invention is not limited to this.
For example, as shown in FIG. 20, the first insulating film 3 may be a SiN film 3B, and the second insulating film 6 may be a SiO ₂ film 6A. This is referred to as a second modification. In the second modification, the first insulating film 3 is the SiN film 3B in the first modification described above.

Here, the SiN first insulating film 3B having a hexagonal columnar opening 3XA and a part 6AX of the SiO ₂ second insulating film 6A are formed on the template substrate 11B.
That is, first, the SiN film 3B is formed to a thickness of about 1000 nm using, for example, a chemical vapor deposition (CVD) method. Next, a SiO ₂ film 6AX is formed to about 100 nm.

Next, for example, by performing electron beam lithography (EB) and etching with a chemical solution or the like, the SiN first insulating film 3B having the hexagonal columnar opening 3XA and the part 6AX of the SiO ₂ second insulating film 6A are formed. The template substrate 11B provided is formed.
When such a template substrate 11B is used, the light receiving layer 4 (here, the light receiving layer 4B made of InAs) is formed so as to have a film thickness approximately equal to the film thickness of the SiN first insulating film 3B of the template substrate 11B. A barrier layer 12 (here, an undoped AlAsSb barrier layer 12A) is formed on the template substrate 11B so as to have a film thickness approximately equal to the film thickness of the part 6AX of the SiO ₂ second insulating film 6A of the template substrate 11B. After forming the second electrode layer 5 (here, the n-type InAs second electrode layer 5B), the remaining portion 6AY of the SiO ₂ second insulating film 6A is formed so as to cover the second electrode layer 5. In this case, the SiO ₂ second insulating film 6A (6AX, 6AY) covers the barrier layer 12 (12A) and the second electrode layer 5 (5B).

By using such a template substrate 11B, the side wall surface of the light receiving layer 4 (4B) is protected by the SiN film 3B, so that the oxidation of the side wall surface of the light receiving layer 4 (4B) is expected to be suppressed. As a result, it is possible to reduce the dark current flowing on the side wall surface of the light receiving layer 4 (4B).
The configuration of the second modification example may be changed as appropriate as long as the effect can be obtained, as in the case of the first modification example described above.

For example, the insulating film of the template substrate 11B may be formed of a SiN film and a SiON film. For example, in the above-described specific example, the first insulating film 3 may be a SiN film.
By the way, as shown in FIGS. 21 and 22, for example, the infrared detector 20 configured as described above is used as one pixel, and a plurality of pixels are arranged on a plane to form an imaging device (infrared imaging device) 21. be able to.

21 and 22 exemplify the case where the infrared detector according to the second modification described above is applied. In FIG. 21, an enlarged portion is provided with the light receiving layer 4. The cross section of the direction along the surface of a partial substrate is shown.
That is, the infrared detector 20 configured as described above is used as one pixel, and a plurality of pixels are arranged on a plane with the first insulating film 3 (3B) interposed therebetween. The element 21 can be configured.

In this case, in the infrared detector array 22, the infrared detectors 20 constituting each pixel are separated by the first insulating film 3 (3B) and arranged on a plane.
Here, the plurality of pixels 20 are preferably arranged in a honeycomb shape as shown in FIG. Thereby, the pixels 20 can be arranged densely, and a high-definition infrared detector array 22 (infrared imaging device 21) can be realized.

The plurality of pixels 20 need only be two-dimensionally arranged on a plane, and need not be arranged in a honeycomb shape. For example, it may be arranged in a grid in the vertical direction and the horizontal direction, or may be arranged at random.
In this embodiment, as shown in FIGS. 21 and 22, the image sensor 21 includes a chip 23 that is connected to the infrared detector array 22 and includes a drive circuit and a readout circuit.

Here, for example, as shown in FIG. 22, the first electrode layer 2 (2A) provided in the infrared detector 20 configured as described above is used as a common electrode layer common to all the pixels 20, and the first electrode 7 is used. Are provided in the peripheral part of the infrared detector array 22, that is, in the peripheral part of the region where the plurality of pixels 20 are arranged, as a common electrode.
Then, a drive circuit and a readout circuit are provided via bumps 25 (output electrodes; here, In bumps) connected to the second electrode 8 provided in the infrared detector 20 constituting each pixel by a surface wiring 24 (metal wiring). And a driving circuit and a readout circuit via a bump 27 (common electrode; In bump here) connected to the first electrode 7 as a common electrode by a surface wiring 26 (metal wiring). The chip | tip 23 containing is connected.

By the way, an imaging system (infrared imaging system) can be comprised as what is provided with the image pick-up element 21 comprised as mentioned above.
For example, as shown in FIG. 23, the imaging system 30 includes a sensor unit 31 including the imaging device 21 configured as described above, a control calculation unit 32 connected to the sensor unit 31, and a display unit 33. An image based on infrared rays incident on the sensor unit 31 may be displayed on the display unit 33.

In this case, the imaging system 30 is configured to include the imaging element 21 configured as described above and the control calculation unit 32 connected to the imaging element 21.
Therefore, according to the infrared detector and the manufacturing method thereof, the imaging device, and the imaging system according to the present embodiment, the effect of reducing the dark current flowing through the side surface of the light receiving layer 4 and improving the performance of the infrared detector. Have

In addition, this invention is not limited to the structure described in embodiment mentioned above, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
Hereinafter, additional notes will be disclosed regarding the above-described embodiment.
(Appendix 1)
A first electrode layer provided above the (111) B substrate;
A first insulating film provided on the first electrode layer and having a hexagonal column-shaped opening;
A hexagonal columnar light-receiving layer provided on the first electrode layer and in the hexagonal columnar opening, and having a side surface in contact with the first insulating film;
A second electrode layer provided on the light receiving layer;
An infrared detector comprising: a second insulating film covering the second electrode layer.

(Appendix 2)
The infrared detector according to appendix 1, wherein the light receiving layer has a smaller cross-sectional area in a direction along the surface of the (111) B substrate than the second electrode layer.
(Appendix 3)
The infrared detector according to appendix 1 or 2, further comprising a barrier layer between at least one of the light receiving layer and the second electrode layer and between the light receiving layer and the first electrode layer.

(Appendix 4)
The light receiving layer is made of any material of InAs, InSb, GaSb, AlSb, is made of a mixed crystal containing any two or more of InAs, InSb, GaSb, and AlSb, or InAs, InSb, GaSb, The infrared detector according to any one of appendices 1 to 3, wherein the infrared detector is made of a superlattice including any two or more types of AlSb.

(Appendix 5)
The infrared detector according to any one of appendices 1 to 4, wherein the first electrode layer is made of InAs.
(Appendix 6)
The first insulating film and said second insulating film, _SiN, or consist of any of the materials SiO 2, SiON, or, _SiN, formed by laminating one or two or more kinds of SiO 2, SiON,
6. The infrared detector according to any one of appendices 1 to 5, wherein at least a region of the first insulating film in contact with a side surface of the light receiving layer is made of SiN.

(Appendix 7)
The infrared detector according to any one of appendices 1 to 6, wherein the (111) B substrate is made of any one of InAs, GaSb, GaAs, and InP.
(Appendix 8)
An imaging device comprising an infrared detector array in which the infrared detector according to any one of appendices 1 to 7 is used as one pixel, and a plurality of pixels are arranged on a plane with the first insulating film interposed therebetween. element.

(Appendix 9)
The imaging device (21) according to appendix 8, wherein the plurality of pixels are arranged in a honeycomb shape.
(Appendix 10)
The imaging device according to appendix 8 or 9, comprising a chip connected to the infrared detector array and including a drive circuit and a readout circuit.

(Appendix 11)
The imaging device according to any one of appendices 8 to 10,
An imaging system comprising: a control calculation unit connected to the imaging element.
(Appendix 12)
(111) forming a first electrode layer above the B substrate;
Forming a first insulating film having a hexagonal column-shaped opening on the first electrode layer;
Forming a hexagonal columnar light-receiving layer on the first electrode layer and in the hexagonal columnar opening so that a side surface is in contact with the first insulating film;
Forming a second electrode layer on the light receiving layer;
And a step of forming a second insulating film so as to cover the second electrode layer.

1 (111) B substrate 1A n-type GaSb (111) B substrate 1B n-type InAs (111) B substrate 2 first electrode layer 2A n-type InAs first electrode layer 3 first insulating film 3A SiO ₂ first insulating film 3B SiN first insulating film 3X, 3XA Hexagonal column-shaped opening 4 Light-receiving layer 4A Hexagonal columnar light-receiving layer made of InAs and GaSb superlattice 4B Hexagonal columnar light-receiving layer made of InAs 5 Second electrode layer 5A p-type GaSb / n Type InAs second electrode layer 5B n-type InAs second electrode layer 6 second insulating film 6A SiO ₂ second insulating film 6AX SiO ₂ part of second insulating film 6AY SiO ₂ remaining part of second insulating film 7 first Electrode 8 Second electrode 9 GaSb buffer layer 9A InAs buffer layer 10 InAsSb etching stopper layer 11, 11A, 11B Template substrate 12 Barrier layer 12A Undoped AlAsSb Barrier Layer 20 Infrared Detector 21 Imaging Device (Infrared Imaging Device)
22 Infrared detector array 23 Chip including drive circuit and readout circuit 24, 26 Surface wiring (metal wiring)
25, 27 Bump 30 Imaging system (Infrared imaging system)
31 Sensor unit 32 Control operation unit 33 Display unit

Claims (10)

A first electrode layer provided above the (111) B substrate;
A first insulating film provided on the first electrode layer and having a hexagonal column-shaped opening;
A hexagonal columnar light-receiving layer provided on the first electrode layer and in the hexagonal columnar opening, and having a side surface in contact with the first insulating film;
A second electrode layer provided on the light receiving layer;
An infrared detector comprising: a second insulating film covering the second electrode layer.   2. The infrared detector according to claim 1, wherein the light receiving layer has a smaller cross-sectional area in a direction along the surface of the (111) B substrate than the second electrode layer.   The infrared detector according to claim 1, further comprising a barrier layer between at least one of the light receiving layer and the second electrode layer and between the light receiving layer and the first electrode layer.   The light receiving layer is made of any material of InAs, InSb, GaSb, AlSb, is made of a mixed crystal containing any two or more of InAs, InSb, GaSb, AlSb, or InAs, InSb, GaSb, The infrared detector according to any one of claims 1 to 3, wherein the infrared detector comprises a superlattice including any two or more of AlSb.   The infrared detector according to claim 1, wherein the first electrode layer is made of InAs. The first insulating film and said second insulating film, _SiN, or consist of any of the materials SiO 2, SiON, or, _SiN, formed by laminating one or two or more kinds of SiO 2, SiON,
The infrared detector according to claim 1, wherein at least a region of the first insulating film in contact with a side surface of the light receiving layer is made of SiN.   An infrared detector array according to claim 1, wherein the infrared detector according to claim 1 is a pixel, and a plurality of pixels are arranged on a plane with the first insulating film interposed therebetween. Image sensor.   The imaging device according to claim 7, wherein the plurality of pixels are arranged in a honeycomb shape. The image sensor according to claim 7 or 8,
An imaging system comprising: a control calculation unit connected to the imaging element. (111) forming a first electrode layer above the B substrate;
Forming a first insulating film having a hexagonal column-shaped opening on the first electrode layer;
Forming a hexagonal columnar light-receiving layer on the first electrode layer and in the hexagonal columnar opening so that a side surface is in contact with the first insulating film;
Forming a second electrode layer on the light receiving layer;
And a step of forming a second insulating film so as to cover the second electrode layer.

Images