JP2006173329A - Light receiving element and its manufacturing method, optical module, and optical transmission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light receiving element easy to integrate and to provide its manufacturing method. <P>SOLUTION: The light receiving element 100 comprises a substrate 101; a first contact layer 112 formed above the substrate 101, an optical absorption layer 114 formed above the first contact layer 112, a second contact layer 116 formed above the optical absorption layer 114, and a condenser 170 formed above the second contact layer 116. At least one of the optical absorption layer 114 and the second contact layer 116 includes a photonic crystal region 140 having a periodic refractive index distribution in a surface direction, and the photonic crystal region 140 includes a defect region 142. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light receiving element, a method for manufacturing the same, an optical module, and an optical transmission device.

  As one of optical communication systems, there is a wavelength division multiplexing (WDM). In WDM optical communication, wavelength division is performed using, for example, an AWG (Arrayed Waveguide Grating) element. In this case, since the element size is several mm square to several cm square, integration may be difficult.

  An object of the present invention is to provide a light-receiving element that can be easily integrated and a method for manufacturing the same. Another object of the present invention is to provide an optical module including the light receiving element, and an optical transmission device having the optical module.

The light receiving element according to the present invention is:
A substrate,
A first contact layer formed above the substrate;
A light absorbing layer formed above the first contact layer;
A second contact layer formed above the light absorption layer;
A condensing lens formed above the second contact layer,
At least one of the light absorption layer and the second contact layer has a photonic crystal region having a periodic refractive index distribution in a plane direction;
The photonic crystal region has a defect region.

  According to this light receiving element, since the wavelength of incident light can be selected by the element itself, for example, the device can be downsized as compared with a case where wavelength selection is performed by an AWG element or the like. As a result, the light receiving elements can be easily integrated.

  In the present invention, other specific objects (hereinafter referred to as “B”) formed above a specific object (hereinafter referred to as “A”) are defined as B directly formed on A and A And B formed via the others on A. Further, in the present invention, forming B above A includes a case where B is formed directly on A and a case where B is formed on A via another on A.

  In the present invention, “periodic” is a concept including “pseudo-periodic”. That is, the photonic crystal region of the present invention includes those having a periodic photonic crystal structure and those having a quasi-periodic photonic crystal structure. Examples of the quasi-periodic photonic crystal structure include a photonic quasicrystal structure (see, for example, M. Notomi, H. Suzuki, T. Tamamura, K. Edagawa, Phys. Rev. Lett. 92 (2004) 123906. ) Or a circular coordinate photonic crystal structure (for example, see JP-A-2004-109737).

In the light receiving element according to the present invention,
A plurality of holes may be formed in the photonic crystal region other than the defect region.

In the light receiving element according to the present invention,
The center of the defect area in plan view is the same as or substantially the same as the center of the light incident on the condenser lens,
The plurality of holes may be arranged at positions symmetrical with respect to the center of the defect region.

The light receiving element according to the present invention is:
A substrate,
Above the substrate, a plurality of light receiving units stacked in order,
A separation layer for electrically separating each of the plurality of light receiving parts;
A condenser lens formed above an uppermost light receiving part among the plurality of light receiving parts,
Each of the light receiving parts
A contact layer;
A light absorbing layer formed above the contact layer;
And another contact layer formed above the light absorption layer,
At least one of the light absorption layer and the other contact layer has a photonic crystal region having a periodic refractive index distribution in a plane direction,
The photonic crystal region has a defect region;
The condensing lens focuses a plurality of lights having different wavelengths in the light absorbing layers of at least two of the light absorbing layers.

  According to this light receiving element, since the wavelength of incident light can be divided by the element itself, the device can be reduced in size as compared with a case where wavelength division is performed by an AWG element or the like. As a result, the light receiving elements can be easily integrated.

In the light receiving element according to the present invention,
Each of the light receiving parts
A plurality of holes formed in the photonic crystal region other than the defect region;
An internal member disposed in the hole,
The absorption wavelength of the light absorption layer of the light receiving unit may be different from the absorption wavelength of the internal member of at least one of the other light receiving units above the light receiving unit.

  In the present invention, the “absorption wavelength” of a specific member refers to the wavelength of light having the maximum absorption intensity among light absorbed by the member.

The light receiving element according to the present invention is:
A substrate,
A first light receiving portion, which is disposed from the substrate side above the substrate and includes a first contact layer, a first light absorption layer, and a second contact layer;
A separation layer formed above the second contact layer;
A second light-receiving portion disposed above the separation layer from the separation layer side and including a third contact layer, a second light absorption layer, and a fourth contact layer;
A condensing lens formed above the fourth contact layer,
At least one of the first light absorption layer and the second contact layer has a first photonic crystal region having a periodic refractive index distribution in a plane direction,
The first photonic crystal region has a first defect region;
At least one of the second light absorption layer and the fourth contact layer has a second photonic crystal region having a periodic refractive index distribution in the plane direction;
The second photonic crystal region has a second defect region;
The condensing lens focuses the light of the first wavelength in the first light absorption layer, and focuses the light of the second wavelength in the second light absorption layer.

In the light receiving element according to the present invention,
The first light receiving unit includes:
A plurality of first holes formed in the first photonic crystal region other than the first defect region;
A first internal member disposed in the first hole,
The second light receiving unit includes:
A plurality of second holes formed in the second photonic crystal region other than the second defect region;
A second internal member disposed in the second hole,
The absorption wavelength of the first light absorption layer may be different from the absorption wavelength of the second internal member.

In the light receiving element according to the present invention,
The condensing lens may have a plurality of lens portions stacked integrally.

An optoelectronic integrated device according to the present invention includes the above-described light receiving device,
TIA (Trans-Impedance Amplifier).

An optical module according to the present invention includes the above-described light receiving element,
A light emitting element.

  An optical transmission device according to the present invention includes the above-described optical module.

The manufacturing method of the light receiving element according to the present invention is as follows:
Forming a semiconductor multilayer film by sequentially laminating at least a first contact layer, a light absorption layer, and a semiconductor layer for constituting a second contact layer above the substrate;
Forming a first contact layer, a light absorption layer, and a second contact layer by patterning the semiconductor multilayer film;
Forming a photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the light absorption layer and the second contact layer;
Forming a condensing lens above the second contact layer,
The photonic crystal region is formed to have a defect region.

The manufacturing method of the light receiving element according to the present invention is as follows:
A step of sequentially stacking and forming a plurality of light receiving portions above the substrate;
Forming a separation layer for electrically separating each of the plurality of light receiving parts;
Forming a condensing lens above the uppermost light receiving part among the plurality of light receiving parts,
The step of forming each of the light receiving portions includes:
Forming a contact layer;
Forming a light absorption layer above the contact layer;
Forming another contact layer above the light absorbing layer;
Forming a photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the light absorption layer and the other contact layer, and
The photonic crystal region is formed to have a defect region,
The condensing lens is formed so that a plurality of lights having different wavelengths are focused on the inside of at least two of the light absorption layers.

The manufacturing method of the light receiving element according to the present invention is as follows:
Forming a first semiconductor multilayer film by sequentially laminating at least a first contact layer, a first light absorption layer, and a semiconductor layer for constituting a second contact layer above the substrate;
Forming a first contact layer, a first light absorption layer, and a second contact layer by patterning the first semiconductor multilayer film;
Forming a first photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the first light absorption layer and the second contact layer;
Above the second contact layer, at least a separation layer, a third contact layer, a second light absorption layer, and a semiconductor layer for forming a fourth contact layer are sequentially stacked to form a second semiconductor multilayer film. And a process of
Forming a separation layer, a third contact layer, a second light absorption layer, and a fourth contact layer by patterning the second semiconductor multilayer film;
Forming a second photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the second light absorption layer and the fourth contact layer;
Forming a condensing lens above the fourth contact layer,
The first photonic crystal region is formed to have a first defect region;
The second photonic crystal region is formed to have a second defect region;
The condensing lens is formed so that the first wavelength light is focused in the first light absorption layer and the second wavelength light is focused in the second light absorption layer.

In the method for manufacturing a light receiving element according to the present invention,
The condensing lens can be formed by a droplet discharge method for discharging a droplet including the material of the condensing lens.

In the method for manufacturing a light receiving element according to the present invention,
Before the step of forming the condenser lens, a step of forming a blocking member for blocking the droplets can be included.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

1. 1. First embodiment 1-1. Structure of Light Receiving Element FIG. 1 is a cross-sectional view schematically showing a light receiving element 100 according to this embodiment. FIG. 2 is a plan view schematically showing the light receiving element 100 shown in FIG. 1 is a view showing a cross section taken along the line II of FIG.

  As shown in FIGS. 1 and 2, the light receiving element 100 according to the present embodiment includes a substrate 101, a light receiving unit 110, and a condenser lens 170. In the present embodiment, a case where the light receiving unit 110 functions as a pin type photodiode will be described.

  As the substrate 101, for example, a GaAs substrate or an InP substrate can be used.

  The light receiving unit 110 is provided on the substrate 101. The light receiving unit 110 includes a first contact layer 112, a light absorption layer 114, and a second contact layer 116. The first contact layer 112 is provided on the substrate 101, the light absorption layer 114 is provided on the first contact layer 112, and the second contact layer 116 is provided on the light absorption layer 114. The first contact layer 112 constitutes a columnar semiconductor deposited body. The planar shape of the first contact layer 112 can be, for example, a quadrangle or a circle. In the example shown in the figure, it is a quadrangle. The light absorption layer 114 and the second contact layer 116 constitute an integral columnar semiconductor deposit. The planar shape of the light absorption layer 114 and the second contact layer 116 can be, for example, a quadrangle or a circle. In the example shown in the figure, it is a quadrangle.

  When, for example, a GaAs substrate is used as the substrate 101, the first contact layer 112 is made of, for example, an n-type GaAs layer, the light absorption layer 114 is made of, for example, an undoped GaInNAs layer, and the second contact layer 116 is made of, for example, a p-type GaAs layer. Can consist of When an InP substrate is used as the substrate 101, for example, the first contact layer 112 is made of, for example, an n-type InGaAs layer, the light absorption layer 114 is made of, for example, an undoped InGaAs layer, and the second contact layer 116 is made of, for example, a p-type. It can consist of an InGaAs layer. Accordingly, the p-type second contact layer 116, the undoped light absorption layer 114, and the n-type first contact layer 112 form a pin structure.

  The light absorption layer 114 and the second contact layer 116 have a photonic crystal region 140 having a periodic refractive index distribution in the plane direction. In the illustrated example, a plurality of holes 144 are formed in the photonic crystal region 140. The hole 144 passes through the second contact layer 116 and extends in the thickness direction of the second contact layer 116. Further, the hole 144 penetrates the light absorption layer 114 and extends in the thickness direction of the light absorption layer 114. As shown in FIGS. 1 and 2, the photonic crystal region 140 has a region where the hole 144 is not formed, that is, a defect region 142. In other words, in the illustrated example, a plurality of holes 144 are arranged around the defect region 142 in a triangular lattice pattern at the same pitch interval. In the illustrated example, the number of holes 144 is 124, but the number can be appropriately increased or decreased. Further, the arrangement of the holes 144 is not limited to a triangular lattice shape, and may be a square lattice shape, for example. Further, the pitch interval of the holes 144 can be changed as appropriate. The holes 144 can also be arranged at different pitch intervals. Further, the hole 144 can be formed at a position that is symmetric with respect to the center of the defect region 142 in plan view. For example, the holes 144 arranged in a triangular lattice pattern shown in FIG. 2 have six-fold rotational symmetry. Further, the depth of the hole 144 is not particularly limited. For example, the hole 144 may not penetrate the second contact layer 116 or may not penetrate the light absorption layer 114. Further, for example, the hole 144 can be formed in the first contact layer 112. In this case, the hole 144 may penetrate the first contact layer 112 or may not penetrate. Note that the hole 144 is formed in the light absorption layer 114, for example, the light receiving element 100 performs wavelength selection more reliably than when the hole 144 is formed only in the second contact layer 116. be able to. The wavelength selection performed by the light receiving element 100 will be described later.

  In plan view, the center of the defect area 142 can be the same as or substantially the same as the center of the light incident on the condenser lens 170. Light can be confined in the defect region 142 by the photonic crystal region 140 as described above.

  As shown in FIG. 1, an internal member 146 is disposed in the hole 144. In the illustrated example, the internal member 146 disposed below the condensing lens 170 is made of the same material as the condensing lens 170, and the internal member 146 disposed below the second electrode 117 is composed of air. In addition, the material of the internal member 146 is not specifically limited, It can select suitably. The state of the internal member 146 can be solid, liquid, gas, or the like.

  Moreover, the 1st contact layer 112 can be used as a light reflection layer as needed. In this case, the first contact layer 112 can reflect the light transmitted without being absorbed by the light absorption layer 114 and return it to the light absorption layer 114 side again. Thereby, the light detection sensitivity of the light receiving element 100 can be improved. The light reflection layer is not particularly limited as long as it has reflectivity with respect to incident light. For example, a distributed Bragg reflection mirror (DBR), a metal layer, or the like can be used.

  A first electrode 113 is formed on the first contact layer 112 as shown in FIGS. 1 and 2. The planar shape of the first electrode 113 can be, for example, a quadrangle as in the illustrated example. The first electrode 113 is formed so as not to contact the light absorption layer 114. A second electrode 117 is formed on the second contact layer 116. The planar shape of the second electrode 117 can be, for example, a ring shape as illustrated. An opening 182 is provided in the second electrode 117, and a part of the upper surface of the second contact layer 116 is exposed through the opening 182. This exposed surface is the light incident surface 180 in the light receiving unit 110. Accordingly, by appropriately setting the planar shape and size of the opening 182, the shape and size of the incident surface 180 can be appropriately set. In the illustrated example, the planar shape of the incident surface 180 is a circle. The first electrode 113 and the second electrode 117 are used to drive the light receiving unit 110.

  A damming member 176 is provided on the second electrode 117. The dam member 176 can dam the condensing lens precursor 170a including the material of the condensing lens 170 (see FIG. 8). That is, the shape of the condensing lens 170 can be controlled by controlling the shape of the blocking member 176. The planar shape of the damming member 176 can be, for example, a ring shape as illustrated. The cross-sectional shape of the damming member 176 can be a square or a triangle, for example. In the illustrated example, it is a rectangle. The second electrode 117 can also be used as a damming member. That is, the second electrode 117 can also dam the condenser lens precursor 170a.

  The condenser lens 170 is formed on a part of the second electrode 117 and the incident surface 180. The condensing lens 170 is formed so as to contact the inner side surface of the damming member 176 and not to contact the upper surface of the damming member 176. The shape of the condenser lens 170 can be convex. More specifically, the shape of the condensing lens can be, for example, a shape obtained by cutting out a part of one sphere as in the illustrated example.

  In the present embodiment, the case where the light receiving unit 110 functions as a pin type photodiode has been described, but the present invention is also applicable to a light receiving element other than the pin type photodiode. Note that examples of the light receiving element to which the present invention can be applied include a pn photodiode, an avalanche photodiode, and an MSM photodiode. These are similarly applied to the first light receiving unit 210 and the second light receiving unit 250 of the second embodiment to be described later.

  The present invention can also be applied to, for example, a wavelength filter. In this case, the first contact layer 112, the first electrode 113, the second contact layer 116, and the second electrode 117 may not be formed.

1-2. Next, an example of a method for manufacturing the light receiving element 100 according to the present embodiment will be described with reference to FIGS. 3 to 8 are cross-sectional views schematically showing one manufacturing process of the light receiving element 100 shown in FIGS. 1 and 2, and each correspond to the cross-sectional view shown in FIG.

  (1) First, the substrate 101 is prepared. Hereinafter, an example in which an InP substrate is used as the substrate 101 will be described.

  Next, the semiconductor multilayer film 120 is formed by epitaxial growth on the surface 101a of the substrate 101, as shown in FIG. Here, the semiconductor multilayer film 120 includes, for example, a first contact layer 112 made of an n-type InGaAs layer, a light absorption layer 114 made of an undoped InGaAs layer, and a second contact layer 116 made of a p-type InGaAs layer. By laminating these layers on the substrate 101 in order, the semiconductor multilayer film 120 is formed.

  The temperature at which the epitaxial growth is performed is appropriately determined depending on the growth method, the raw material, the type of the substrate 101, or the type, thickness, and carrier density of the semiconductor multilayer film 120 to be formed, but is generally 450 ° C. to 800 ° C. Is preferred. Further, the time required for performing the epitaxial growth is also appropriately determined in the same manner as the temperature. In addition, as a method of epitaxial growth, a metal-organic vapor phase epitaxy (MOVPE) method, a molecular beam epitaxy (MBE) method, a liquid phase epitaxy (LPE) method, or the like can be used.

  (2) Next, as shown in FIG. 4, the semiconductor multilayer film 120 is patterned to form a first contact layer 112, a light absorption layer 114, and a second contact layer 116 having desired shapes. Thereby, the light receiving part 110 is formed. The patterning of the semiconductor multilayer film 120 can be performed by a known lithography technique and etching technique.

  (3) Next, as shown in FIG. 5, a photonic crystal region 140 is formed inside the light absorption layer 114 and the second contact layer 116. Specifically, periodically arranged holes 144 are formed in the light absorption layer 114 and the second contact layer 116. However, the hole 144 is not formed in the defect region 142. The hole 144 can be formed using a lithography technique, an etching technique, an EB (Electron Beam) processing technique, or the like.

  (4) Next, as shown in FIG. 6, the first electrode 113 is formed on the first contact layer 112, and the second electrode 117 is formed on the second contact layer 116.

These electrodes can be formed using, for example, a known electrode forming technique (for example, a combination of a vacuum deposition method, a lift-off method, and an annealing process). Note that the second electrode 117 is formed to have an opening 182. The opening 182 exposes a part of the upper surface of the second contact layer 116. This exposed surface becomes the incident surface 180. As the first electrode 113, for example, a laminated film of an alloy of gold (Au) and zinc (Zn) and gold (Au) can be used. As the second electrode 117, for example, an alloy of gold (Au) and germanium (Ge), a laminated film of nickel (Ni), and gold (Au) can be used. Note that, as the first electrode 113 and the second electrode 117, for example, a metal (non-alloy metal) that can be formed without performing an annealing process can be used. Examples of non-alloy metal include tungsten silicide (WSi _x ).

  (5) Next, as shown in FIG. 7, a damming member 176 is formed on the second electrode 117. As the damming member 176, for example, a resin such as polyimide, a dielectric layer such as SiN, or the like can be used. The damming member 176 can be patterned using, for example, a known lithography technique and etching technique.

  (6) Next, as shown in FIG. 8, a condensing lens precursor 170a is formed. Specifically, a liquid material droplet 170b for forming the condensing lens 170 is ejected onto the upper surface of the second contact layer 116 to form the condensing lens precursor 170a. The droplet 170b is discharged until the condensing lens precursor 170a is formed so that the condensing lens 170 has a desired shape. At this time, the condensing lens precursor 170 a is blocked by the inner side surface of the blocking member 176. The liquid material has a property of being curable by applying energy (light, heat, etc.). Examples of the liquid material include an ultraviolet curable resin and a thermosetting resin precursor. Examples of the ultraviolet curable resin include an ultraviolet curable acrylic resin and an epoxy resin. Examples of the thermosetting resin include a thermosetting polymer to which high refractive index metal oxide nanoparticles are added, a thermosetting polyimide resin, and the like.

  Examples of a method for ejecting the droplet 170b include a dispenser method and a droplet ejection method. The dispenser method is a general method for discharging droplets, and is effective when the droplets 170b are discharged over a relatively wide area. The droplet discharge method is a method of discharging droplets using an inkjet head 192 for discharging droplets, and the position at which droplets are discharged can be controlled in units of μm. Further, since the amount of liquid droplets to be ejected can be controlled in units of picoliters, a condensing lens 170 having a fine structure can be manufactured.

  Examples of the droplet discharge method include (i) a method in which pressure is generated by changing the size of bubbles in the liquid by heat and a liquid is discharged from the ink jet nozzle 190, or (ii) a method in which a piezoelectric element is used. There is a method of discharging liquid from the inkjet nozzle 190 by pressure. From the viewpoint of controllability of pressure, the method (ii) is desirable.

  Alignment between the position of the inkjet nozzle 190 of the inkjet head 192 and the ejection position of the droplet 170b is performed using a known image recognition technique used in an exposure process or an inspection process in a general semiconductor integrated circuit manufacturing process. . For example, as shown in FIG. 8, alignment between the position of the inkjet nozzle 190 of the inkjet head 192 and the opening 182 of the second electrode 117 is performed by image recognition. After alignment, the voltage applied to the inkjet head 192 is controlled, and then the droplet 170b is ejected.

  For example, when the discharge angle of the droplet 170b discharged from the inkjet nozzle 190 has some variation, if the position where the droplet 170b has landed is inside the opening 177 of the blocking member 176, the blocking member 176 The condensing lens precursor 170a wets and spreads in the area surrounded by, and the position is automatically corrected.

  In the illustrated example, the condensing lens precursor 170 a enters the hole 144. The degree to which the condensing lens precursor 170a enters the hole 144 can be controlled, for example, by adjusting the viscosity of the condensing lens precursor 170a, the opening diameter of the hole 144, and the like.

  (7) Next, as shown in FIGS. 1 and 2, the condenser lens precursor 170 a is cured to form the condenser lens 170. Specifically, energy (light, heat, etc.) is applied to the condensing lens precursor 170a. When the condensing lens precursor 170a is cured, an appropriate method is used depending on the material type of the condensing lens precursor 170a. Specifically, for example, addition of thermal energy or irradiation with light such as ultraviolet rays or laser light can be given.

  Through the above steps, the light receiving element 100 of the present embodiment is obtained as shown in FIGS.

  In the above-described example, the case where the first contact layer 112, the light absorption layer 114, and the second contact layer 116 are sequentially stacked on the substrate 101 has been described. However, for example, only the second contact layer 116 is formed. The light absorption layer 114 and the second contact layer 116 can be attached to each other after being formed over another substrate. In this case, after the photonic crystal region 140 is formed in at least one of the light absorption layer 114 and the second contact layer 116, both can be bonded together. The light absorption layer 114 and the second contact layer 116 can be bonded using a known substrate bonding technique. Similarly, for example, only the second contact layer 116 and the light absorption layer 114 may be formed on another substrate, and then the first contact layer 112 and the light absorption layer 114 may be bonded together. In this case, after forming the photonic crystal region 140 in at least one of the first contact layer 112, the light absorption layer 114, and the second contact layer 116, the two can be bonded together.

1-3. Action / Effect According to the light receiving element 100 according to the present embodiment, the wavelength of the incident light A (see FIG. 1) can be reliably selected, and high light detection sensitivity can be obtained. Specifically, it is as follows.

  The light receiving element 100 according to the present embodiment has a photonic crystal region 140. The photonic crystal region 140 can confine light in the defect region 142. That is, the photonic crystal region 140 can constitute a resonator (for example, a point defect resonator). Incident light A is coupled to the resonance mode of this resonator. As a result, the light coupled to the resonance mode is absorbed by the light absorption layer 114 and detected as a photocurrent. Therefore, the light receiving element 100 according to the present embodiment can detect light having a desired wavelength or wavelength band. In other words, the light receiving element 100 according to the present embodiment can perform wavelength selection of the incident light A.

  Furthermore, according to the light receiving element 100 of this embodiment, the incident light A can be condensed by the condenser lens 170 and can be incident on the defect region 142. That is, the path of the incident light A is schematically shown as an arrow A shown in FIG. As a result, compared with the case where the light receiving element 100 does not have the condenser lens 170, the coupling efficiency of the incident light A to the resonator described above can be improved. Therefore, the wavelength of the incident light A can be selected more reliably, and the light detection sensitivity of the light receiving element 100 can be increased.

  Further, according to the light receiving element 100 according to the present embodiment, since the wavelength of incident light can be selected by the element itself, the device can be downsized compared to the case where wavelength selection is performed by an AWG element or the like, for example. Can be planned. As a result, the light receiving element 100 can be easily integrated.

2. Second embodiment 2-1. FIG. 9 is a cross-sectional view schematically showing a light receiving element 200 according to this embodiment. FIG. 10 is a plan view schematically showing the light receiving element 200 shown in FIG. 9 is a view showing a cross section taken along line II-II in FIG.

  As shown in FIGS. 9 and 10, the light receiving element 200 according to the present embodiment includes a substrate 201, a first light receiving unit 210, a separation layer 230, a second light receiving unit 250, and a condenser lens 270. Including. In the present embodiment, a case where the first light receiving unit 210 and the second light receiving unit 250 function as a pin type photodiode will be described.

  As the substrate 201, for example, a GaAs substrate or an InP substrate can be used.

  The first light receiving unit 210 is provided on the substrate 201. The first light receiving unit 210 includes a first contact layer 212, a first light absorption layer 214, and a second contact layer 216. The first contact layer 212 is provided on the substrate 201, the first light absorption layer 214 is provided on the first contact layer 212, and the second contact layer 216 is provided on the first light absorption layer 214. The first contact layer 212 constitutes a columnar semiconductor deposited body. The planar shape of the first contact layer 212 can be, for example, a quadrangle or a circle. In the example shown in the figure, it is a quadrangle. The first light absorption layer 214 and the second contact layer 216 constitute an integrated columnar semiconductor deposit. The planar shapes of the first light absorption layer 214 and the second contact layer 216 can be, for example, a quadrangle or a circle. In the example shown in the figure, it is a quadrangle.

  When a GaAs substrate is used as the substrate 201, the first contact layer 212 is made of, for example, an n-type GaAs layer, the first light absorption layer 214 is made of, for example, an undoped GaInNAs layer, and the second contact layer 216 is made of, for example, a p-type. It can consist of a GaAs layer. When an InP substrate, for example, is used as the substrate 201, the first contact layer 212 is made of, for example, an n-type InGaAs layer, the first light absorption layer 214 is made of, for example, an undoped InGaAs layer, and the second contact layer 216 is made of, for example, It can consist of a p-type InGaAs layer. Therefore, the p-type second contact layer 216, the undoped first light absorption layer 214, and the n-type first contact layer 212 form a pin structure.

  The first light absorption layer 214 and the second contact layer 216 have a first photonic crystal region 240 having a periodic refractive index distribution in the plane direction. In the illustrated example, a plurality of first holes 244 are formed in the first photonic crystal region 240. The first hole 244 passes through the second contact layer 216 and extends in the thickness direction of the second contact layer 216. Further, the first hole 244 passes through the first light absorption layer 214 and extends in the thickness direction of the first light absorption layer 214. As shown in FIGS. 9 and 10, the first photonic crystal region 240 has a region where the first hole 244 is not formed, that is, a first defect region 242. In other words, in the illustrated example, a plurality of first holes 244 are arranged around the first defect region 242 in a triangular lattice pattern at the same pitch interval. In the illustrated example, the number of the first holes 244 is 124, but the number can be appropriately increased or decreased. Further, the arrangement of the first holes 244 is not limited to a triangular lattice shape, and may be a square lattice shape, for example. Further, the pitch interval of the first holes 244 can be changed as appropriate. Also, the first holes 244 can be arranged at different pitch intervals. Further, the first hole 244 can be formed at a position that is symmetric with respect to the center of the first defect region 242 in plan view. For example, the first holes 244 arranged in a triangular lattice shape shown in FIG. 10 have six-fold rotational symmetry. Further, the depth of the first hole 244 is not particularly limited. For example, the first hole 244 may not penetrate the second contact layer 216 or may not penetrate the first light absorption layer 214. Further, for example, the first hole 244 can be formed in the first contact layer 212. In this case, the first hole 244 may penetrate the first contact layer 212 or may not penetrate. The first hole 244 is formed in the first light absorption layer 214, for example, compared to the case where the first hole 244 is formed only in the second contact layer 216, the light receiving element 200 is more Wavelength division can be reliably performed. The wavelength division performed by the light receiving element 200 will be described later.

  In plan view, the center of the first defect region 242 can be the same as or substantially the same as the center of the light incident on the condenser lens 270. The first photonic crystal region 240 as described above can confine light in the first defect region 242.

  As shown in FIG. 9, a first internal member 246 is disposed in the first hole 244. In the illustrated example, the first inner member 246 is made of air. The material of the first internal member 246 is not particularly limited and can be selected as appropriate. The state of the first internal member 246 can be solid, liquid, gas, or the like.

  A first electrode 213 is formed on the first contact layer 212 as shown in FIGS. 1 and 2. The planar shape of the first electrode 213 can be, for example, a quadrangle as in the illustrated example. The first electrode 213 is formed so as not to contact the first light absorption layer 214. A second electrode 217 is formed on the second contact layer 216. The planar shape of the second electrode 217 can be, for example, a quadrangle as in the illustrated example. The second electrode 217 can be formed so as not to contact the separation layer 230. The first electrode 213 and the second electrode 217 are used to drive the first light receiving unit 210.

  The separation layer 230 is provided on the first light receiving unit 210. More specifically, the separation layer 230 is provided on the second contact layer 216. The separation layer 230 constitutes a columnar semiconductor deposited body. The planar shape of the separation layer 230 can be a square or a circle, for example. In the example shown in the figure, it is a quadrangle.

The separation layer 230 electrically separates the first light receiving unit 210 and the second light receiving unit 250. More specifically, the separation layer 230 electrically separates the second contact layer 216 and a third contact layer 252 described later. That is, as the separation layer 230, an insulating or semi-insulating layer can be used. For example, as the separation layer 230, a layer obtained by oxidizing an InAlAs layer, a layer obtained by oxidizing an AlGaAs layer, a layer obtained by oxidizing an InGaAsP layer, an undoped GaAs layer, an undoped InGaAs layer, a SiN layer, a SiO ₂ layer, or the like may be used. it can.

  The second light receiving unit 250 is provided on the separation layer 230. The second light receiving unit 250 includes a third contact layer 252, a second light absorption layer 254, and a fourth contact layer 256. The third contact layer 252 is provided on the separation layer 230, the second light absorption layer 254 is provided on the third contact layer 252, and the fourth contact layer 256 is provided on the second light absorption layer 254. The third contact layer 252 constitutes a columnar semiconductor deposited body. The planar shape of the third contact layer 252 can be, for example, a quadrangle or a circle. In the example shown in the figure, it is a quadrangle. The second light absorption layer 254 and the fourth contact layer 256 constitute an integrated columnar semiconductor deposit. The planar shape of the second light absorption layer 254 and the fourth contact layer 256 can be, for example, a quadrangle or a circle. In the illustrated example, it is circular.

  When a GaAs substrate, for example, is used as the substrate 201, the third contact layer 252 is made of, for example, an n-type GaAs layer, the second light absorption layer 254 is made of, for example, an undoped GaInNAs layer, and the fourth contact layer 256 is made of, for example, a p-type. It can consist of a GaAs layer. Further, when an InP substrate is used as the substrate 201, the third contact layer 252 is made of, for example, an n-type InGaAs layer, the second light absorption layer 254 is made of, for example, an undoped InGaAs layer, and the fourth contact layer 256 is made of, for example, It can consist of a p-type InGaAs layer. Accordingly, the p-type fourth contact layer 256, the undoped second light absorption layer 254, and the n-type third contact layer 252 form a pin structure.

  Note that the first light absorption layer 214 and the second light absorption layer 254 may be made of the same material or different materials. Here, the different materials are compounds including the same constituent elements and include the case where the composition ratios of the respective elements are different. As will be described later, when the light receiving element 200 according to the present embodiment performs wavelength division in a narrow wavelength band, the same material is desirable. Conversely, when performing wavelength division of a wide range of wavelength bands by the light receiving element 200 according to the present embodiment, it is desirable that the materials be different. In addition, the first light absorption layer 214 and the second light absorption layer 254 can suppress the light absorbed by the first light absorption layer 214 from being absorbed by the second light absorption layer 254. The material can be selected.

  The second light absorption layer 254 and the fourth contact layer 256 have a second photonic crystal region 241 having a periodic refractive index distribution in the plane direction. In the illustrated example, a plurality of second holes 245 are formed in the second photonic crystal region 241. The second hole 245 passes through the fourth contact layer 256 and extends in the thickness direction of the fourth contact layer 256. Further, the second hole 245 passes through the second light absorption layer 254 and extends in the thickness direction of the second light absorption layer 254. As shown in FIGS. 9 and 10, the second photonic crystal region 241 has a region where the second hole 245 is not formed, that is, a second defect region 243. In other words, in the illustrated example, a plurality of the second holes 245 are arranged around the second defect region 243 in a triangular lattice pattern at the same pitch interval. In the illustrated example, the number of the second holes 245 is 124, but the number can be appropriately increased or decreased. Further, the arrangement of the second holes 245 is not limited to a triangular lattice shape, and may be a square lattice shape, for example. Further, the pitch interval of the second holes 245 can be changed as appropriate. In addition, the second holes 245 may be arranged at different pitch intervals. The second hole 245 can be formed at a position that is symmetric with respect to the center of the second defect region 243 in plan view. For example, the second holes 245 arranged in a triangular lattice shape shown in FIG. 10 have six-fold rotational symmetry. Further, the depth of the second hole 245 is not particularly limited. For example, the second hole 245 may not penetrate the fourth contact layer 256 or may not penetrate the second light absorption layer 254. For example, the second hole 245 may be formed in the third contact layer 252. In this case, the second hole 245 may penetrate the third contact layer 252 or may not penetrate. Note that the second hole 245 is formed in the second light absorption layer 254. For example, the light receiving element 200 is more formed than in the case where the second hole 245 is formed only in the fourth contact layer 256. Wavelength division can be reliably performed. The wavelength division performed by the light receiving element 200 will be described later. Further, in the illustrated example, the second holes 245 and the first holes 244 are formed with the same number, arrangement, pitch interval, and depth. However, the number, arrangement, pitch may be changed as necessary. At least one of the interval and the depth can be varied.

  In plan view, the center of the second defect region 243 can be the same as or substantially the same as the center of the light incident on the condenser lens 270. Light can be confined in the second defect region 243 by the second photonic crystal region 241 as described above.

  As shown in FIG. 9, a second internal member 247 is disposed in the second hole 245. In the illustrated example, the second inner member 247 is made of air. The material of the second internal member 247 is not particularly limited and can be selected as appropriate. The state of the second internal member 247 can be solid, liquid, gas, or the like.

  A third electrode 253 is formed on the third contact layer 252 as shown in FIGS. 9 and 10. The planar shape of the third electrode 253 can be, for example, a quadrangle as in the illustrated example. The third electrode 253 is formed so as not to contact the second light absorption layer 254. A fourth electrode 257 is formed on the fourth contact layer 256. The planar shape of the fourth electrode 257 can be, for example, a ring shape as shown in the illustrated example. The fourth electrode 257 is provided with an opening 282, and a part of the upper surface of the fourth contact layer 256 is exposed through the opening 282. This exposed surface is the light incident surface 280 of the second light receiving unit 250. Therefore, by appropriately setting the planar shape and size of the opening 282, the shape and size of the incident surface 280 can be appropriately set. In the illustrated example, the planar shape of the incident surface 280 is a circle. The third electrode 253 and the fourth electrode 257 are used to drive the second light receiving unit 250.

  A blocking member 276 is provided on the fourth electrode 257. The damming member 276 can dam the first lens portion precursor 272 including the material of the first lens portion 272 and the second lens portion precursor 274a including the material of the second lens portion 274 (see FIGS. 17 and 17). 18). That is, by controlling the shape of the blocking member 276, the shapes of the first lens portion 272 and the second lens portion 274 can be controlled. The planar shape of the damming member 276 can be, for example, a ring shape as shown in the illustrated example. The cross-sectional shape of the damming member 276 can be, for example, a quadrangle or a triangle. In the illustrated example, it is a rectangle. In the present embodiment, the position of the upper surface of the damming member 276 is 7.2 μm higher than the position of the incident surface 280. Note that the fourth electrode 257 can also be used as a blocking member. That is, the fourth electrode 257 can dam the first lens part precursor 272a and the second lens part precursor 274a.

  The condenser lens 270 includes a first lens part 272 and a second lens part 274. The first lens portion 272 is formed on a part of the fourth electrode 257 and the incident surface 280. The first lens portion 272 is formed so as to contact the inner side surface of the damming member 276 and not to contact the upper surface of the damming member 276. The second lens unit 274 is stacked on the first lens unit 272. That is, the first lens portion 272 and the second lens portion 274 are integrally formed. The second lens part 274 is formed on the first lens part 272 and the damming member 276. The second lens portion 274 is formed so as not to contact the outer side surface of the damming member 276.

  The center of the first lens part 272 in plan view and the center of the second lens part 274 in plan view can be formed to be the same or substantially the same as the center of the light incident on the condenser lens 270. .

  The first lens part 272 and the second lens part 274 may have a convex shape. More specifically, the shape of the first lens portion 272 and the second lens portion 274 can be, for example, a shape in which a part of one sphere is cut out as shown in the illustrated example.

  In the present embodiment, the case where the condenser lens 270 includes two lens portions (the first lens portion 272 and the second lens portion 274) has been described. The number is not particularly limited and can be one or more. For example, the number of lens parts constituting the condensing lens 270 is two or more, and each lens part has a different refractive index (the refractive index is reduced as it goes to the outside), thereby efficiently refracting light. Can do.

  In the present embodiment, the case where the light receiving element 200 includes two light receiving units (the first light receiving unit 210 and the second light receiving unit 250) is described. However, the number of light receiving units included in the light receiving element 200 is as follows. If it is two or more, it will not specifically limit. The number of light receiving units included in the light receiving element 200 can be set as appropriate according to the number of light wavelengths divided by the light receiving element 200. The wavelength division performed by the light receiving element 200 will be described later.

2-2. Operation of the light receiving element The operation of the light receiving element 200 of the present embodiment will be described below. The following driving method of the light receiving element 200 is an example, and various modifications can be made without departing from the gist of the present invention.

  FIG. 11 is a cross-sectional view schematically showing the operation of the light receiving element 200 of the present embodiment, and corresponds to the cross-sectional view shown in FIG. The light receiving element 200 has a function of converting a plurality of optical signals composed of a plurality of lights having different wavelengths into current signals corresponding to the respective optical signals. Specifically, it is as follows.

  First, a plurality of lights having different wavelengths emitted from the outside of the light receiving element 200 are incident on the light receiving element 200. More specifically, for example, first, a plurality of lights having different wavelengths are emitted from a light emitting element (not shown). The plurality of lights enter, for example, one end face of an optical waveguide (not shown), propagate in the optical waveguide, and exit from the other end face. The plurality of emitted light is incident on the second lens portion 274 of the light receiving element 200. Here, for convenience, light of wavelength λ1 (hereinafter referred to as “first wavelength light λ1”) and light of wavelength λ2 (hereinafter referred to as “second wavelength light λ2”) are the second lens unit 274. An example of incidence on the light will be described. A case where the wavelength λ1 is longer than the wavelength λ2 will be described. For example, the wavelength λ1 can be 1.55 μm, and the wavelength λ2 can be 1.31 μm. The paths of the first wavelength light λ1 and the second wavelength light λ2 are schematically indicated by arrows in FIG. For example, the angle θ formed between the first wavelength light λ1 and the second wavelength light λ2 incident on the second lens unit 274 and the horizontal plane may be 83.7 °. Further, for example, as the first wavelength light λ1 and the second wavelength light λ2 incident on the second lens unit 274, the spot radius on the incident surface 280 is 20 μm when the condensing lens 270 is not present. Aperture light can be used.

  The light λ <b> 1 having the first wavelength and the light λ <b> 2 having the second wavelength are refracted at the interface between the outside of the second lens unit 274 (for example, air) and the second lens unit 274. At this time, the light λ1 having the first wavelength and the light λ2 having the second wavelength have different wavelengths, and thus have different refraction angles. Specifically, the light λ1 having the first wavelength has a larger refraction angle than the light λ2 having the second wavelength. As a result, as shown in FIG. 11, the light λ2 having the second wavelength is more condensed than the light λ1 having the first wavelength.

  Next, the first wavelength light λ <b> 1 and the second wavelength light λ <b> 2 propagated through the second lens unit 274 are incident on the first lens unit 272. The light λ1 having the first wavelength and the light λ2 having the second wavelength are refracted at the interface between the second lens portion 274 and the first lens portion 272. At this time, similarly to the case of refraction at the interface between the outside of the second lens unit 274 and the second lens unit 274 described above, the light λ1 of the first wavelength has a larger refraction angle than the light λ2 of the second wavelength. . As a result, as shown in FIG. 11, the light λ2 having the second wavelength is more condensed than the light λ1 having the first wavelength.

  Then, the focal point of the light λ2 having the second wavelength condensed by the condensing lens 270 (the first lens unit 272 and the second lens unit 274) as compared with the light λ1 having the first wavelength is as shown in FIG. And the second defect region 243 of the second light absorption layer 254. The second wavelength light λ <b> 2 is coupled to the resonance mode of the point defect resonator formed by the second photonic crystal region 241. As a result, the second wavelength light λ <b> 2 coupled to the resonance mode is mainly absorbed by the second light absorption layer 254. Specifically, first, the light λ <b> 2 having the second wavelength propagated in the first lens unit 272 is incident on the second light receiving unit 250 from the incident surface 280. Next, the light λ <b> 2 having the second wavelength passes through the fourth contact layer 256 and is mainly absorbed by the second light absorption layer 254.

  Similarly, the focus of the first wavelength light λ1 collected by the condenser lens 270 is focused in the first defect region 242 of the first light absorption layer 214 as shown in FIG. Then, the light λ1 having the first wavelength is coupled to the resonance mode of the point defect resonator formed by the first photonic crystal region 240. As a result, the first wavelength light λ 1 coupled to the resonance mode is mainly absorbed by the first light absorption layer 214. Specifically, first, the light λ <b> 1 having the first wavelength that has propagated through the first lens unit 272 is incident on the second light receiving unit 250 from the incident surface 280. Next, the light λ <b> 1 having the first wavelength propagates through the second light receiving unit 250 and the separation layer 230 and is incident on the first light receiving unit 210. Next, the light λ 1 having the first wavelength passes through the second contact layer 216 and is mainly absorbed by the first light absorption layer 214.

  Therefore, in the light receiving element 200 according to this embodiment, the light λ1 having the first wavelength is mainly absorbed by the first light absorption layer 214. As a result, photoexcitation occurs in the first light absorption layer 214, and electrons and holes are generated. Arise. Then, due to the electric field applied between the first electrode 213 and the second electrode 217, electrons move to the first electrode 213 and holes move to the second electrode 217. As a result, a current (photocurrent) is generated in the first light receiving unit 210 in the direction from the first contact layer 212 to the second contact layer 216. That is, an optical signal composed of the light λ1 having the first wavelength can be converted into a current signal.

  Similarly, the light λ2 having the second wavelength is mainly absorbed by the second light absorption layer 254, and as a result, photoexcitation occurs in the second light absorption layer 254, and electrons and holes are generated. Then, due to the electric field applied between the third electrode 253 and the fourth electrode 257, electrons move to the third electrode 253 and holes move to the fourth electrode 257, respectively. As a result, a current (photocurrent) is generated from the third contact layer 252 to the fourth contact layer 256 in the second light receiving unit 250. That is, an optical signal composed of the light λ2 having the second wavelength can be converted into a current signal.

  In this embodiment, for the sake of convenience, an example in which two lights having different wavelengths (light λ1 having the first wavelength and light λ2 having the second wavelength) are incident on the condenser lens 270 has been described. The number of lights having different wavelengths incident on the lens 270 is not particularly limited as long as it is two or more. The number of lights having different wavelengths incident on the condenser lens 270 can be appropriately set according to the usage pattern of the light receiving element 200.

2-3. Next, an example of a method for manufacturing the light receiving element 200 according to the present embodiment will be described with reference to FIGS. 9, 10, and 12 to 18. 12 to 18 are cross-sectional views schematically showing one manufacturing process of the light receiving element 200 shown in FIGS. 9 and 10, and each correspond to the cross-sectional view shown in FIG.

  (1) First, the substrate 201 is prepared. Hereinafter, an example in which an InP substrate is used as the substrate 201 will be described.

  Next, a first semiconductor multilayer film (not shown) is formed by epitaxial growth on the surface 201 a of the substrate 201. Here, the first semiconductor multilayer film includes, for example, a first contact layer 212 made of an n-type InGaAs layer, a first light absorption layer 214 made of an undoped InGaAs layer, and a second contact layer 216 made of a p-type InGaAs layer. . By laminating these layers on the substrate 201 in order, a first semiconductor multilayer film is formed. The epitaxial growth of the first semiconductor multilayer film can be performed in the same manner as the epitaxial growth of the semiconductor multilayer film 120 (see FIG. 3) of the first embodiment described above. The composition of the material of each layer can be determined as appropriate.

  As described above, the film thickness of each layer constituting the first semiconductor multilayer film is such that the first wavelength light λ1 is focused in the first light absorption layer 214, and the second wavelength light λ2 is focused on the second light. The value can be set as appropriate so as to fit within the absorption layer 254. In addition, the thickness of each layer constituting the first semiconductor multilayer film can be set in consideration of the shift of the focal position due to the optical axis shift. For example, as for the thickness of each layer constituting the first semiconductor multilayer film, the thickness of the first contact layer 212 is 0.2 μm, the thickness of the first light absorption layer 214 is 0.3 μm, and the film of the second contact layer 216. The thickness can be 0.1 μm or the like.

  Next, as shown in FIG. 12, the first semiconductor multilayer film is patterned to form a first contact layer 212, a first light absorption layer 214, and a second contact layer 216 having desired shapes. Thereby, the 1st light-receiving part 210 is formed. The patterning of the first semiconductor multilayer film can be performed by a known lithography technique and etching technique.

  (2) Next, as shown in FIG. 13, a first photonic crystal region 240 is formed inside the first light absorption layer 214 and the second contact layer 216. The formation of the first photonic crystal region 240 can be performed in the same manner as the formation of the photonic crystal region 140 of the first embodiment described above.

(3) Next, a second semiconductor multilayer film (not shown) is formed by epitaxial growth on the surface 216a of the second contact layer 216. Here, the second semiconductor multilayer film includes, for example, a layer made of an InAlAs layer (hereinafter referred to as a “layer to be a separation layer”) 230a, a third contact layer 252 made of an n-type InGaAs layer, and an undoped InGaAs layer. It consists of a second light absorption layer 254 and a fourth contact layer 256 made of a p-type InGaAs layer. By laminating these layers on the second contact layer 216 in order, a second semiconductor multilayer film is formed. The epitaxial growth of the second semiconductor multilayer film can be performed in the same manner as the epitaxial growth of the first semiconductor multilayer film described above. The composition of the material of each layer can be determined as appropriate. For example, the composition of the material of the first light absorption layer 214 and the first light absorption layer 214 so that the light absorbed by the first light absorption layer 214 can be suppressed from being absorbed by the second light absorption layer 254. The composition of the material of the two-light absorption layer 254 can be made different. Specifically, for example, the first light absorption layer 214 is made of an In _0.53 Ga _0.47 As layer, and the second light absorption layer 254 is made of an In _0.4 Ga _0.6 As layer. it can. Further, by increasing the Al composition of the InAlAs layer that is the layer 230a serving as the separation layer, the layer 230a serving as the separation layer can be easily oxidized in the subsequent oxidation step (see FIG. 15). In the present invention, the Al composition of the InAlAs layer is the composition of aluminum (Al) with respect to the group III element.

  As described above, the film thickness of each layer constituting the second semiconductor multilayer film is such that the first wavelength light λ1 is focused in the first light absorption layer 214 and the second wavelength light λ2 is focused on the second light. The value can be set as appropriate so as to fit within the absorption layer 254. Further, the film thickness of each layer constituting the second semiconductor multilayer film can be set in consideration of the shift of the focal position due to the optical axis shift. For example, the thickness of each layer constituting the second semiconductor multilayer film is 0.2 μm for the layer 230 a serving as the separation layer, 0.2 μm for the third contact layer 252, and the second light absorption layer 254. The film thickness can be 0.3 μm, the film thickness of the fourth contact layer 256 can be 0.1 μm, and the like.

  Next, as shown in FIG. 14, the second semiconductor multilayer film is patterned to form a layer 230 a, a third contact layer 252, a second light absorption layer 254, and a fourth contact layer 256 that serve as separation layers having a desired shape. Form. Thereby, the 2nd light-receiving part 250 is formed. The patterning of the second semiconductor multilayer film can be performed by a known lithography technique and etching technique.

  (4) Next, as shown in FIG. 15, by separating the substrate 201 on which the first light receiving unit 210 and the second light receiving unit 250 are formed by the above process in a water vapor atmosphere at about 400 ° C., for example, separation is performed. The separation layer 230 is formed by oxidizing the layer 230a to be a layer from the side surface. The oxidation of the layer 230a serving as the separation layer is performed until the entire layer 230a serving as the separation layer is oxidized.

  Through the above steps, a stacked body of the first light receiving unit 210, the separation layer 230, and the second light receiving unit 250 is formed.

  Next, as shown in FIG. 15, a second photonic crystal region 241 is formed inside the second light absorption layer 254 and the fourth contact layer 256. The formation of the second photonic crystal region 241 can be performed in the same manner as the formation of the first photonic crystal region 240 described above.

  (5) Next, as shown in FIG. 16, the first electrode 213 is formed on the first contact layer 212, the second electrode 217 is formed on the second contact layer 216, and the third contact layer 252 is formed. A third electrode 253 is formed, and a fourth electrode 257 is formed on the fourth contact layer 256.

  These electrodes can be formed using, for example, a known electrode forming technique (for example, a combination of a vacuum deposition method, a lift-off method, and an annealing process). Note that the fourth electrode 257 is formed to have an opening 282. The opening 282 exposes part of the upper surface of the fourth contact layer 256. This exposed surface becomes the incident surface 280. As the first electrode 213 and the third electrode 253, for example, a laminated film of an alloy of gold (Au) and zinc (Zn) and gold (Au) can be used. As the second electrode 217 and the fourth electrode 257, for example, a laminated film of an alloy of gold (Au) and germanium (Ge), nickel (Ni), and gold (Au) can be used. In addition, as the first to fourth electrodes 213, 217, 253, and 257, for example, a metal (non-alloy metal) that can form an electrode without performing annealing treatment can be used.

  Next, as shown in FIG. 16, a damming member 176 is formed on the fourth electrode 257. The dam member 276 can be formed in the same manner as the dam member 176 of the first embodiment described above.

  (6) Next, as shown in FIG. 17, a first lens portion precursor 272a is formed. The formation of the first lens portion precursor 272a can be performed in the same manner as the formation of the condensing lens precursor 170a of the first embodiment described above. In the illustrated example, the first lens portion precursor 272a is prevented from entering the second hole 245. The degree to which the first lens part precursor 272a enters the second hole 245 can be controlled, for example, by adjusting the viscosity of the first lens part precursor 272a, the opening diameter of the second hole 245, and the like.

  (7) Next, as shown in FIG. 18, the first lens part precursor 272a is cured to form the first lens part 272. The first lens portion precursor 272a can be cured in the same manner as the condensing lens precursor 170a of the first embodiment described above.

  As described above, the structure and material of the first lens portion 272 are such that the first wavelength light λ1 is focused in the first light absorption layer 214 and the second wavelength light λ2 is focused in the second light absorption layer 254. It can be appropriately selected to fit inside. For example, the radius of curvature of the outer edge of the first lens unit 272 may be 25 μm, and the height of the highest point of the first lens unit 272 from the incident surface 280 may be 32 μm. Further, for example, the material of the first lens portion 272 is a high refractive index metal oxide nanoparticle having a refractive index of 1.98 for the first wavelength light λ1 and a refractive index of 2.00 for the second wavelength light λ2. A thermosetting polymer to which is added can be used.

  Next, as shown in FIG. 18, the second lens portion precursor 274a is formed. Specifically, a liquid material droplet 274b for forming the second lens unit 274 is ejected onto the upper surface of the first lens unit 272 to form the second lens unit precursor 274a. At this time, the second lens portion precursor 274a is dammed by a corner portion 279 constituted by the upper surface of the damming member 276 and the outer side surface. In addition, detailed description is abbreviate | omitted about the point similar to formation of the 1st lens part precursor 272a mentioned above.

  (8) Next, as shown in FIGS. 9 and 10, the second lens portion precursor 274 a is cured to form the second lens portion 274. The second lens portion precursor 274a can be cured in the same manner as the first lens portion precursor 272a described above.

  As described above, the structure and material of the second lens unit 274 are such that the first wavelength light λ1 is focused in the first light absorption layer 214, and the second wavelength light λ2 is focused in the second light absorption layer 254. It can be appropriately selected to fit inside. For example, the radius of curvature of the outer edge of the second lens portion 274 may be 40 μm, and the height of the second lens portion 274 from the highest incident surface 180 may be 67 μm. For example, the material of the second lens unit 274 is an epoxy resin having a refractive index of 1.58 for the first wavelength light λ1 and a refractive index of 1.6 for the second wavelength light λ2. it can. Note that the first lens portion 272 and the second lens portion 274 can be made of the same material or different materials. For example, when the first lens portion 272 and the second lens portion 274 are made of different materials, the light can be refracted more greatly. In this case, the refractive index of the material of the first lens part 272 is preferably larger than the refractive index of the material of the second lens part 274. For example, the refractive index of vinyl acetate is 1.450 to 1.470, the refractive index of epoxy resin is 1.550 to 1.610, the refractive index of phenoxy resin is 1.598, and the refractive index of polyimide is 1.780, the refractive index of the thermosetting polymer to which the high refractive index metal oxide nanoparticles are added is about 2.0 (or more). Therefore, by appropriately selecting these materials, the refractive index of the material of the first lens portion 272 can be made larger than the refractive index of the material of the second lens portion 274.

  Through the above steps, as shown in FIGS. 9 and 10, the light receiving element 200 of the present embodiment is obtained.

  As in the first embodiment described above, after forming the first photonic crystal region 240 in at least one of the first contact layer 212, the first light absorption layer 214, and the second contact layer 216. Both can also be pasted together. Then, after forming the second photonic crystal region 241 in at least one of the third contact layer 252, the second light absorption layer 254, and the fourth contact layer 256, they can be bonded together.

2-4. Action / Effect According to the light receiving element 200 according to the present embodiment, as described above, a plurality of optical signals composed of a plurality of lights having different wavelengths can be converted into current signals corresponding to the respective optical signals. The desired wavelength division can be performed by appropriately selecting at least one of the structure and material of the condenser lens 270. For example, wavelength division can be performed by converting a plurality of optical signals composed of a plurality of lights having very close wavelengths into current signals corresponding to the respective optical signals. Therefore, wavelength division in a narrow wavelength band can be performed. Of course, wavelength division of a wide range of wavelength bands can also be performed.

  Furthermore, according to the light receiving element 200 according to the present embodiment, the wavelength division of incident light (for example, the first wavelength light λ1 and the second wavelength light λ2 as shown in FIG. 11) can be reliably performed, And it can have high photodetection sensitivity. Specifically, it is as follows.

  The light receiving element 200 according to the present embodiment includes a first photonic crystal region 240 and a second photonic crystal region 241. The first photonic crystal region 240 can confine light in the first defect region 242, and the second photonic crystal region 241 can confine light in the second defect region 243. That is, the first photonic crystal region 240 and the second photonic crystal region 241 can constitute a resonator (for example, a point defect resonator). As described above, incident light is coupled to the resonance mode of the resonator. As a result, the first wavelength light λ 1 coupled to the resonance mode is absorbed by the first light absorption layer 214, and the second wavelength light λ 2 coupled to the resonance mode is absorbed by the second light absorption layer 254. Therefore, according to the light receiving element 200 according to the present embodiment, the light having the desired wavelength λ1 (or the desired wavelength band) can be detected by the first light receiving unit 210, and the other desired wavelength λ2 ( Alternatively, the second light receiving unit 250 can detect light in a desired wavelength band. In other words, the light receiving element 200 according to the present embodiment can perform wavelength division of incident light more reliably.

  According to the light receiving element 200 of the present embodiment, the light λ1 having the first wavelength can be condensed by the condenser lens 270 and can be incident on the first defect region 242, and the light λ2 having the second wavelength can be incident. The light can be condensed and incident on the second defect region 243. As a result, compared with the case where the light receiving element 200 does not include the condenser lens 270, the coupling efficiency of the incident light to the resonator described above can be improved. Therefore, the wavelength division of incident light can be more reliably performed, and the light detection sensitivity of the light receiving element 200 can be increased.

  Further, according to the light receiving element 200 according to the present embodiment, since the wavelength of incident light can be divided by the element itself, for example, the device can be downsized compared to the case where wavelength division is performed by an AWG element or the like. Can be planned. As a result, the light receiving element 200 can be easily integrated.

  Further, according to the light receiving element 200 according to the present embodiment, the absorption wavelength of the second internal member 247 included in the second light receiving unit 250 is different from the absorption wavelength of the first light absorption layer 214 of the first light receiving unit 210. Can do. Accordingly, the light λ1 having the first wavelength absorbed by the first light absorption layer 214 can be suppressed from being absorbed by the second internal member 247 when passing through the second internal member 247. . As a result, the light detection sensitivity of the first light receiving unit 210 can be increased.

  Further, according to the light receiving element 200 according to the present embodiment, since the condensing lens 270 is formed above the incident surface 280, the allowable range of the optical axis deviation is widened. That is, according to the light receiving element 200 according to the present embodiment, the optical axis tolerance is improved.

  In addition, according to the light receiving element 200 according to the present embodiment, the first light receiving unit 210 and the second light receiving unit 250 are stacked through only the separation layer 230, so that the device can be miniaturized. . As a result, the light receiving element 200 can be easily integrated.

  In addition, according to the method for manufacturing the light receiving element 200 according to the present embodiment, for example, compared to the case where the first light receiving unit 210 and the second light receiving unit 250 are bonded and stacked using solder or the like. It is possible to provide the light receiving element 200 that can manufacture the element 200 with good reproducibility and has high reliability.

3. Third Embodiment Next, an optoelectronic integrated device 300 and an optical module 700 to which the light receiving device 100 according to the first embodiment is applied will be described with reference to FIG. FIG. 19 is a cross-sectional view schematically showing the optoelectronic integrated device 300 and the optical module 700 according to this embodiment. In the optoelectronic integrated device 300 and the optical module 700 of the present embodiment, the light receiving device 200 of the second embodiment described above can be used instead of the light receiving device 100 of the first embodiment. The same applies to the fourth and fifth embodiments described later.

  The optoelectronic integrated device 300 includes a light receiving device 100 and a TIA (Trans-Impedance Amplifier) 350 as shown in FIG. The TIA 350 is configured by, for example, a heterojunction bipolar transistor. The light receiving element 100 and the TIA 350 are formed on the submount substrate 406.

  The optical module 700 includes a receiving unit 400, a transmitting unit 500, and an electronic circuit unit 600. The electronic circuit unit 600 includes an amplifier circuit unit 610 and a drive circuit unit 620.

  The receiving unit 400 includes a submount substrate 406, an optoelectronic integrated device 300, a housing unit 402, and a glass unit 404.

  The transmission unit 500 includes a submount substrate 508, a light emitting element 510, a monitor photodiode 512, an oblique glass unit 504, and a housing unit 502. The light emitting element 510 and the monitor photodiode 512 are formed on the submount substrate 508.

  The casing unit 402 is formed of a resin material, and is formed integrally with a sleeve 420 and a condensing unit 405 described later. Similarly, the housing portion 502 is formed of a resin material and is formed integrally with a sleeve 520 described later. As the resin material, a material that can transmit light is selected. For example, polymethyl methacrylate (PMMA), epoxy resin, phenol resin, diallyl phthalate, phenyl methacrylate, fluorine resin used for plastic optical fiber (POF). A polymer or the like can be employed.

  The sleeves 420 and 520 are formed in a shape in which a light guide member (not shown) such as an optical fiber can be fitted from the outside, and constitute a part of the peripheral wall of the accommodation spaces 422 and 522. The condensing part 405 condenses and sends out the optical signal from the light guide member. Thereby, the loss of light from the light guide member can be reduced, and the light coupling efficiency between the light receiving element 100 and the light guide member can be improved.

  The oblique glass portion 504 is provided in the accommodation space 522 and between the sleeve 520 and the light emitting element 510. The oblique glass portion 504 reflects and transmits light from the light emitting element 510. The monitor photodiode 512 receives the light reflected by the oblique glass portion 504. The drive circuit unit 620 adjusts the amount of light emitted by the light emitting element 510 in accordance with the amount of light received by the monitor photodiode 512. The light transmitted through the oblique glass portion 504 is sent out to a light guide member fitted in the sleeve 520 of the transmission unit 500.

  The light emitting element 510 converts an electrical signal input from the outside into an optical signal and outputs the optical signal to the outside through the light guide member. The light receiving element 100 receives an optical signal through the light guide member, converts this into a current, and sends the converted current to the TIA 350. The TIA 350 converts the received current into a voltage output, amplifies it, and sends it to the electronic circuit unit 600. The amplifier circuit unit 610 performs control so that the voltage output does not exceed a certain level, and outputs the voltage output to the outside. In addition, description of external terminals, such as an output terminal and input terminal of an electrical signal, is omitted.

  As described above, the light receiving element 100 is used in the optoelectronic integrated element 300 and the optical module 700.

4). Fourth Embodiment FIG. 20 is a diagram schematically showing a light transmission device 90 according to a fourth embodiment to which the present invention is applied. The light transmission device 90 connects electronic devices 92 such as a computer, a display, a storage device, and a printer to each other. The electronic device 92 may be an information communication device. The light transmission device 90 may be one in which plugs 96 are provided at both ends of the cable 94. The cable 94 can include a light guide member (for example, an optical fiber). The plug 96 contains the optical module 700 according to the third embodiment. Since the light guide member is built in the cable 94 and the optical module 700 is built in the plug 96, it is not shown. The relationship between the light guide member and the optical module 700 is as described in the third embodiment.

  Optical modules 700 according to the third embodiment are provided at both ends of the light guide member. As shown in FIGS. 19 and 20, the light receiving element 100 installed at one end of the light guide member converts an optical signal into an electrical signal, and then transmits the electrical signal via the TIA 350 and the electronic circuit unit 600. To the electronic device 92. A light emitting element 510 is installed at the other end of the light guide member. That is, in the light emitting element 510, the electrical signal output from the electronic device 92 is converted into an optical signal. This optical signal travels through the light guide member and is input to the light receiving element 100.

  As described above, according to the optical transmission device 90 of the present embodiment, information transmission between the electronic devices 92 can be performed by an optical signal.

5. Fifth Embodiment FIG. 21 is a diagram schematically showing a usage pattern of a light transmission device 90 according to a fifth embodiment to which the present invention is applied. The light transmission device 90 is connected between the electronic devices 80. As the electronic device 80, a liquid crystal display monitor or a digital CRT (may be used in the fields of finance, mail order, medical care, education, etc.), liquid crystal projector, plasma display panel (PDP), digital TV, retail store Cash register (POS for Point of Sale Scanning), video, tuner, game device, printer, and the like.

  As described above, the embodiments of the present invention have been described in detail. However, those skilled in the art can easily understand that many modifications can be made without departing from the novel matters and effects of the present invention. . Accordingly, all such modifications are intended to be included in the scope of the present invention.

  For example, a plurality of the above-described light receiving elements can be arrayed. Further, for example, in the above-described embodiment, even if the p-type and the n-type in each semiconductor layer are switched, it does not depart from the spirit of the present invention. In the light receiving element of the above-described embodiment, the InGaAs type and the GaInNAs type have been described, but other material types such as Si type, Ge type, GaAs type, It is also possible to use a semiconductor material such as an InGaAsP system or an HgCdTe system.

FIG. 3 is a cross-sectional view schematically showing the light receiving element according to the first embodiment. The top view which shows typically the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 1st Embodiment. Sectional drawing which shows typically the light receiving element which concerns on 2nd Embodiment. The top view which shows typically the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically operation | movement of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. Sectional drawing which shows typically the manufacturing method of the light receiving element which concerns on 2nd Embodiment. The figure which shows typically the optical module which concerns on 3rd Embodiment. The figure which shows typically the light transmission apparatus which concerns on 4th Embodiment. The figure which shows typically the usage type of the optical transmission apparatus which concerns on 5th Embodiment.

Explanation of symbols

80 electronic device, 90 light transmission device, 92 electronic device, 94 cable, 96 plug, 100 light receiving element, 101 substrate, 110 light receiving portion, 112 first contact layer, 113 first electrode, 114 light absorption layer, 116 second contact Layer, 117 second electrode, 120 semiconductor multilayer film, 140 photonic crystal region, 142 defect region, 144 hole, 146 internal member, 170 condensing lens, 176 damming member, 177 opening, 180 incident surface, 182 opening , 190 inkjet nozzle, 192 inkjet head, 200 light receiving element, 201 substrate, 210 first light receiving portion, 212 first contact layer, 213 first electrode, 214 first light absorbing layer, 216 second contact layer, 217 second electrode , 230 Separation layer, 240 First photonic crystal Region, 241 second photonic crystal region, 242 first defect region, 243 second defect region, 244 first hole, 245 second hole, 246 first inner member, 247 second inner member, 250 second light receiving portion, 252 3rd contact layer, 253 3rd electrode, 254 2nd light absorption layer, 256 4th contact layer, 257 4th electrode, 270 Condensing lens, 272 1st lens part, 274 2nd lens part, 276 Damping member 279 Corner, 280 Incident surface, 282 Opening, 300 Optoelectronic integrated device, 350 TIA, 400 Receiver, 402 Case, 404 Glass, 405 Light collector, 406 Submount substrate, 420 Sleeve, 422 Storage space , 500 transmitting unit, 502 housing unit, 504 glass unit, 508 submount substrate, 510 light emitting element, 51 Monitor photodiode, 520 a sleeve 522 housing space, 600 electronic circuit unit, 610 amplifier unit, 620 drive circuit section, 700 optical module

Claims (16)

A substrate,
A first contact layer formed above the substrate;
A light absorbing layer formed above the first contact layer;
A second contact layer formed above the light absorption layer;
A condensing lens formed above the second contact layer,
At least one of the light absorption layer and the second contact layer has a photonic crystal region having a periodic refractive index distribution in a plane direction;
The photonic crystal region is a light receiving element having a defect region. In claim 1,
A light receiving element in which a plurality of holes are formed in the photonic crystal region other than the defect region. In claim 2,
The center of the defect area in plan view is the same as or substantially the same as the center of the light incident on the condenser lens,
The light receiving element, wherein the plurality of holes are arranged at positions symmetrical with respect to a center of the defect region. A substrate,
Above the substrate, a plurality of light receiving units stacked in order,
A separation layer for electrically separating each of the plurality of light receiving parts;
A condenser lens formed above an uppermost light receiving part among the plurality of light receiving parts,
Each of the light receiving parts
A contact layer;
A light absorbing layer formed above the contact layer;
And another contact layer formed above the light absorption layer,
At least one of the light absorption layer and the other contact layer has a photonic crystal region having a periodic refractive index distribution in a plane direction,
The photonic crystal region has a defect region;
The said condensing lens is a light receiving element which adjusts the focus of several light from which a wavelength differs in the inside of the said light absorption layer of the at least 2 layer of each said light absorption layer. In claim 4,
Each of the light receiving parts
A plurality of holes formed in the photonic crystal region other than the defect region;
An internal member disposed in the hole,
The light receiving element, wherein an absorption wavelength of the light absorbing layer of the light receiving unit is different from an absorption wavelength of the internal member included in at least one of the other light receiving units above the light receiving unit. A substrate,
A first light receiving portion, which is disposed from the substrate side above the substrate and includes a first contact layer, a first light absorption layer, and a second contact layer;
A separation layer formed above the second contact layer;
A second light-receiving portion disposed above the separation layer from the separation layer side and including a third contact layer, a second light absorption layer, and a fourth contact layer;
A condensing lens formed above the fourth contact layer,
At least one of the first light absorption layer and the second contact layer has a first photonic crystal region having a periodic refractive index distribution in a plane direction,
The first photonic crystal region has a first defect region;
At least one of the second light absorption layer and the fourth contact layer has a second photonic crystal region having a periodic refractive index distribution in the plane direction;
The second photonic crystal region has a second defect region;
The condensing lens is a light receiving element in which a first wavelength light is focused in the first light absorption layer, and a second wavelength light is focused in the second light absorption layer. In claim 6,
The first light receiving unit includes:
A plurality of first holes formed in the first photonic crystal region other than the first defect region;
A first internal member disposed in the first hole,
The second light receiving unit includes:
A plurality of second holes formed in the second photonic crystal region other than the second defect region;
A second internal member disposed in the second hole,
The light receiving element, wherein an absorption wavelength of the first light absorption layer is different from an absorption wavelength of the second internal member. In any one of Claims 4-7,
The condensing lens is a light receiving element having a plurality of lens portions stacked integrally. The light receiving element according to any one of claims 1 to 8,
An optoelectronic integrated device including a TIA (Trans-Impedance Amplifier). The light receiving element according to any one of claims 1 to 8,
An optical module comprising a light emitting element.   An optical transmission device comprising the optical module according to claim 10. Forming a semiconductor multilayer film by sequentially laminating at least a first contact layer, a light absorption layer, and a semiconductor layer for constituting a second contact layer above the substrate;
Forming a first contact layer, a light absorption layer, and a second contact layer by patterning the semiconductor multilayer film;
Forming a photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the light absorption layer and the second contact layer;
Forming a condensing lens above the second contact layer,
The method for manufacturing a light receiving element, wherein the photonic crystal region is formed to have a defect region. A step of sequentially stacking and forming a plurality of light receiving portions above the substrate;
Forming a separation layer for electrically separating each of the plurality of light receiving parts;
Forming a condensing lens above the uppermost light receiving part among the plurality of light receiving parts,
The step of forming each of the light receiving portions includes:
Forming a contact layer;
Forming a light absorption layer above the contact layer;
Forming another contact layer above the light absorbing layer;
Forming a photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the light absorption layer and the other contact layer, and
The photonic crystal region is formed to have a defect region,
The said condensing lens is a manufacturing method of a light receiving element formed so that the focus of the several light from which a wavelength differs may be adjusted to the inside of the said light absorption layer of at least 2 layer of each said light absorption layer. Forming a first semiconductor multilayer film by sequentially laminating at least a first contact layer, a first light absorption layer, and a semiconductor layer for constituting a second contact layer above the substrate;
Forming a first contact layer, a first light absorption layer, and a second contact layer by patterning the first semiconductor multilayer film;
Forming a first photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the first light absorption layer and the second contact layer;
Above the second contact layer, at least a separation layer, a third contact layer, a second light absorption layer, and a semiconductor layer for forming a fourth contact layer are sequentially stacked to form a second semiconductor multilayer film. And a process of
Forming a separation layer, a third contact layer, a second light absorption layer, and a fourth contact layer by patterning the second semiconductor multilayer film;
Forming a second photonic crystal region having a periodic refractive index distribution in a plane direction inside at least one of the second light absorption layer and the fourth contact layer;
Forming a condensing lens above the fourth contact layer,
The first photonic crystal region is formed to have a first defect region;
The second photonic crystal region is formed to have a second defect region;
The condensing lens is formed so that the first wavelength light is focused in the first light absorption layer, and the second wavelength light is focused in the second light absorption layer. Device manufacturing method. In any one of Claims 12-14,
The method for manufacturing a light receiving element, wherein the condenser lens is formed by a droplet discharge method for discharging a droplet including a material of the condenser lens. In claim 15,
A method for manufacturing a light receiving element, including a step of forming a blocking member for blocking the droplet before the step of forming the condenser lens.

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