JP2003215361A - Optical functional element and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical functional element having high mechanical strength and high reliability and a method for producing the same. <P>SOLUTION: A photo acceptance unit 6 which accepts light reflected by a grating 5 after passing through a photonic crystal 4 is disposed on a silicon layer 3 as a substrate layer. The photonic crystal 4 has a three-dimensional periodic structure in which a large number of silicon regions 41 comprising Si and a large number of compound regions 42 comprising SiO<SB>2</SB>are three- dimensionally and alternately arranged with a period approximate to the wavelength of propagated light and the grating 5 has a one-dimensional periodic structure in which a large number of compound regions 51 comprising SiO<SB>2</SB>are one-dimensionally arranged at intervals approximate to the wavelength of propagated light. The region in the silicon layer 3 except the compound regions 42, 51 constitute a substrate region and the compound regions 42, 51 are selectively formed in the silicon layer 3 by utilizing lithography and ion implantation. Each silicon region 41 comprises part of the substrate region. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical functional device and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the rapid development of high-density wavelength communication, which requires complicated optical control, optical waveguides, light-emitting devices,
An optical integrated circuit including a photoelectric conversion element such as a light receiving element, a wavelength filter, a grating (diffraction grating), and the like has been receiving attention.

Here, as an optical waveguide, a conventional silica-based waveguide has a small relative refractive index difference of 0.5% or less between a core having a high refractive index and a clad having a low refractive index. Optical waveguides using various core materials with high refractive index are being developed in various places. The above-mentioned relative refractive index difference has a core refractive index n ₁ and a cladding refractive index n ₂
Then, it is a value obtained by (n ₁ ² −n ₂ ² ) / (2n ₁ ² ).

Further, as an optical functional element applied to an optical integrated circuit or the like, a periodic structure or a quasi-periodic structure composed of two kinds of substances having different refractive indexes and having an arrangement of about the wavelength of the propagating light (about half the wavelength) is provided. Photonic crystals having a structure are being researched and developed in various places. As the photonic crystal, one having a two-dimensional periodic structure in which substances having different refractive indices are alternately arranged in a two-dimensional periodic structure and one having a three-dimensional periodic structure in which three-dimensional periodic arrangement is known are known. ing.

As the photonic crystal having a two-dimensional periodic structure, one having a large number of circular holes arranged in a two-dimensional periodic manner on one surface side of a semiconductor substrate and a large number of columnar pillars made of semiconductor are two. One having a two-dimensional periodic structure is known, and a photonic crystal having such a two-dimensional periodic structure uses a lithography technique (photolithography technique or electron beam lithography technique) and a dry etching technique. Can be formed. In the photonic crystal having these two-dimensional periodic structures, one of the two substances having different refractive indexes is a semiconductor and the other is air. The photonic crystal with a two-dimensional periodic structure is
Since the periodic structure is not formed in the remaining one dimension of the three dimensions, the characteristic of the photonic crystal is not shown in the remaining one dimension.

As a photonic crystal having a three-dimensional periodic structure, for example, one having a three-dimensional periodic structure called a self-cloning type as shown in FIG. 5 (see Japanese Patent Laid-Open No. 10-335758). Or called a woodpile type as shown in FIG.
Having a dimensional periodic structure (Japanese Patent Laid-Open No. 2001-74955)
(See Japanese Patent Publication).

The photonic crystal 4'shown in FIG. 5 has a substrate (for example, a silicon substrate) 1 having circular holes (not shown) formed on one surface thereof so as to have a two-dimensional periodic structure.
0 on the one surface side of the first thin film layer 4 made of a first substance (for example, amorphous Si: hereinafter referred to as a-Si)
a and a second thin film layer 4b made of a _second substance (for example, SiO ₂ ) are alternately laminated, and the substrate 10 is formed in a plane parallel to the one surface of the substrate 10. The periodic structure reflecting the period of the irregularities on the one surface is formed, and the periodicity due to the alternate lamination appears in the thickness direction of the substrate 10, and has a three-dimensional periodic structure as a whole.

Hereinafter, the photonic crystal 4'shown in FIG.
An example of the manufacturing method will be briefly described.

First, a resist layer for an electron beam is applied on one surface of a substrate 10 made of a silicon substrate, and the resist layer is patterned to form the circular hole, and then the exposed portion of the substrate 10 is removed. By etching to a predetermined depth set according to the above cycle, periodic unevenness is formed on one surface of the substrate 10, and the resist layer is removed. The period of the periodic structure of the irregularities is set to be about ½ of the wavelength of incident light.

As described above, the first periodical structure is formed on the one surface of the substrate 10 by the rf bias sputtering method in which the uneven structure is formed on the one surface of the substrate 10 and the resist layer is removed, and then etching is performed simultaneously with the deposition. the material (e.g., a-Si) the first film layer 4a and the second material comprising (eg, SiO ₂₎ photonic crystal 4 by laminating a second film layer 4b made of alternating ' It is formed. The technique for forming the photonic crystal 4'is called autocloning technique.

Further, the photonic crystal 4 "shown in FIG.
Is a three-dimensional array of raft-assembled rod-shaped bodies 4c shifted by half a cycle, and one of the two substances (rod-shaped bodies 4c) having different refractive indices is a semiconductor (for example, Ga).
As, InP, etc.) and the other becomes air.

Hereinafter, the photonic crystal 4 "shown in FIG.
An example of the manufacturing method will be briefly described with reference to FIG.

First, an AlGaAs layer 21 and a GaAs layer 22 are sequentially epitaxially grown on one surface side of a substrate 20 made of a GaAs substrate to obtain a structure shown in FIG. 7A, and then a photolithography technique and a dry etching technique are used. The GaAs layer 22 is processed into a stripe shape by using to form the rod-shaped bodies 4c each of which is a part of the GaAs layer 22, thereby obtaining the structure shown in FIG. 7B. Then, two substrates 20 having the same rod-shaped body 4c formed on one surface side
The rod-shaped bodies 4c are overlapped with each other so that they are in contact with each other and intersect with each other so that the structure shown in FIG. 7 (c) is obtained, and then one of the substrates 20 is polished and wet-etched. Then, the structure shown in FIG. 7D is obtained. After that, the structure shown in FIG. 7D is overlapped and bonded by fusion bonding so that the uppermost rod-shaped bodies 4c are in contact with and intersect with each other, and one substrate 20 is removed. The photonic crystal 4 ″ having the structure shown in e) is obtained.

[0014]

A photonic crystal having a two-dimensional periodic structure has a relatively easy mechanical manufacturing process, but since one of its constituent materials is air, it has a relatively low mechanical strength, such as foreign matter (dust or dust). There was a problem that the reliability was low, because there was a problem that dust etc. might enter.

Further, defects due photonic crystal three-dimensional periodic structure 4 'is shown in FIG. 5, employing the process of depositing alternating significantly different substances in the distance between the a-Si and atomic that SiO ₂ There was a problem that the occurrence of was a problem. Further, the photonic crystal 4 ″ having the three-dimensional periodic structure shown in FIG. 6 has a problem that the manufacturing process is complicated and cost reduction is difficult. Moreover, one of the constituent materials has mechanical strength such as GaAs or InP. Since is a relatively weak compound semiconductor material and the other is air, there is a problem that mechanical strength is relatively weak and reliability is low as a whole.

Further, since the conventional grating is also patterned by the etching technique or the like, there is a problem that the mechanical strength is relatively weak and the reliability is low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical functional element having high mechanical strength and high reliability, and a method for manufacturing the same.

[0018]

According to a first aspect of the present invention, there are provided a large number of compound regions which are made of a compound containing a constituent substance of a base layer and which are selectively formed in the base layer and have a refractive index different from that of the base layer. The base layer is a region other than the compound region in the base layer, and the compound regions are regularly arranged at intervals of about the wavelength of light propagating through the base layer. Since the compound regions selectively formed therein are regularly arranged at intervals of about the wavelength of light propagating through the base layer, it can be used as an optical functional device having high mechanical strength and high reliability. . The compound region is continuous with the base region by being selectively formed in the base layer.

According to a second aspect of the invention, in the first aspect of the invention, the constituent material of the base region is silicon, and the constituent material of the compound region is silicon oxide or silicon nitride. The stability can be increased.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the base region and the compound region are one-dimensionally arranged alternately with a period of about the wavelength of the light. Since it has, it can be used as an optical functional element having a grating having high mechanical strength and high reliability.

According to a fourth aspect of the present invention, in the first or second aspect of the invention, a periodic structure is provided in which the base region and the compound region are two-dimensionally arranged alternately at a period of about the wavelength of the light. Since it has, it can be used as an optical functional element having a photonic crystal having a two-dimensional periodic structure with high mechanical strength and high reliability.

According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the base region and the compound region have a periodic structure in which they are three-dimensionally arranged alternately at a period of about the wavelength of the light. Therefore, it can be used as an optical functional element having a photonic crystal having a three-dimensional periodic structure with high mechanical strength and high reliability.

A sixth aspect of the present invention is the method for manufacturing an optical functional element according to the third or fourth aspect, in which a portion corresponding to a region where the compound region is to be formed is opened on one surface of the base layer. And a mask layer forming step of forming a mask layer, and introducing an element for forming the compound region from the one surface side of the base layer on which the mask layer is formed into the base layer as ions. And a photonic crystal having a two-dimensional periodic structure having high mechanical strength and high reliability is used in a general semiconductor manufacturing process. It can be easily formed in the base layer by utilizing the lithographic technique and the ion implantation technique.

According to a seventh aspect of the present invention, there is provided the method for manufacturing an optical functional element according to the fifth aspect, in which a compound region farthest in the depth direction of the base layer is to be formed on one surface of the base layer. In the mask layer forming step of forming a mask layer having openings at corresponding portions, and in the substrate layer as an element for forming the compound region from the one surface side of the substrate layer having the mask layer formed as ions. A compound region forming step of forming a compound region by introducing the compound region into the compound region forming step, wherein in the compound region forming step, an element for forming the compound region is used as ions through the mask layer from the one surface side of the base layer. The number of arrangements of the compound regions in the depth direction of the base layer is the ion implantation step of introducing the compound region into the region where the compound region is to be formed with an acceleration voltage set so that The mechanical strength is high, and the accelerating voltage of the ions is changed stepwise according to the depth position of the region where the compound region is to be formed in the depth direction. High 3
A photonic crystal having a three-dimensional periodic structure can be easily formed by using a lithography technique and an ion implantation technique used in a general semiconductor manufacturing process. The number of cycles of the compound region in the depth direction of the base layer is equal to the specified number.

According to the invention of claim 8, in the invention of claim 7, in the compound region forming step, the acceleration voltage is reduced each time the ion implantation step is repeated, so that the photonic crystal having a three-dimensional periodic structure is formed. It can be formed in the base layer with good controllability.

According to a ninth aspect of the invention, in the invention of the seventh aspect, the accelerating voltage is increased each time the ion implantation step is repeated in the compound region forming step, so that a photonic crystal having a three-dimensional periodic structure is formed. It can be formed in the base layer with good controllability.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The optical functional element of this embodiment is shown in FIG.
And as shown in FIG. 2, the substrate 1 made of a silicon substrate
A single-crystal silicon layer 3 is formed on top of the insulating film 2 made of a silicon oxide film.
A photonic crystal 4 having a dimensional periodic structure and a grating 5 are formed separately in the left-right direction in FIG. A light receiving element 6 is provided on the surface of the silicon layer 3 corresponding to the grating 5. Here, the light receiving element 6 is a pin photodiode using an InGaAs-based material as a crystal material (constituent material), and has one surface (front surface or back surface) in the thickness direction as a light receiving surface, and the light receiving surface is the silicon layer 3. It is arranged so as to face the surface. In short, the light receiving element 2
Has a lower surface in FIG. 2 as a light receiving surface. As the light receiving wavelength of the light receiving element 6, for example, a range of about 0.8 μm to 1.7 μm which is a wavelength band for optical communication is set.

By the way, in the optical functional device of this embodiment, the silicon layer 3 also serves as an optical waveguide, and the light in the wavelength band that can pass through the photonic crystal 4 in the optical signal propagating through the optical waveguide. It becomes possible to selectively irradiate only the signal to the grating 5 and receive the light reflected by the grating 5 toward the light receiving element 6 to be received by the light receiving element 6 and converted into an electric signal. There is. As can be seen from the above description, the photonic crystal 4 and the grating 5 each have a function of controlling the light propagating through the silicon layer 3.

The photonic crystal 4 has a large number of silicon regions 41 made of silicon and silicon oxide (SiO ₂ ).
And a large number of compound regions 42 each of which has a three-dimensional periodic structure in which three compound regions 42 are alternately arranged three-dimensionally at a period of about the wavelength of the propagating light (for example, about one-half of the wavelength). Here, each silicon region 41 and each compound region 42 have a rectangular parallelepiped shape, and the silicon regions 41 and the compound regions 42 are alternately arranged in the above-described cycle in the left-right direction, the up-down direction, and the direction orthogonal to the paper surface in FIG. Has been done.
In the present embodiment, the silicon layer 3 constitutes a base layer forming the photonic crystal 4 and the grating 5. Therefore, the compound regions 42 are regularly arranged at intervals of about the wavelength of light propagating through the silicon layer 3 which is the base layer. Further, the compound region 42 is composed of a compound containing silicon (SiO ₂ ) which is a constituent material of the base layer. The silicon region 41
Has a refractive index of 3.5, the compound region 42 has a refractive index of 1.5, and the silicon region 41 and the compound region 42 have different refractive indices.

The grating 5 is made of silicon oxide (S
A large number of compound regions 51 made of iO ₂ ) have a one-dimensional periodic structure in which they are one-dimensionally arranged at intervals of about the wavelength of the propagating light (for example, about ½ of the wavelength). Therefore, the compound regions 51 are regularly arranged at intervals of about the wavelength of light propagating through the silicon layer 3 which is the base layer. Further, the compound region 51 is composed of a compound containing silicon (SiO ₂ ) which is a constituent material of the base layer. Here, each compound region 51 has a prismatic shape, is arranged in the left-right direction in FIG. 2, and is formed in a stripe shape as a whole.

By the way, in the present embodiment, in the silicon layer 3 which is the base layer, the regions other than the compound regions 42 and 51 constitute the base region, and the compound regions 42 and 51 are selectively formed in the silicon layer 3. Each silicon region 41 is constituted by a part of the base region.

Next, a method of forming the photonic crystal 4 will be described with reference to FIG.

First, a mask material layer (for example, a resist layer) is formed on the surface of the silicon layer 3, and the farthest in the depth direction of the silicon layer 3 by a lithography technique (photolithography technique or electron beam lithography technique). The structure shown in FIG. 3A is obtained by performing a mask layer forming step of forming a mask layer 7 in which a region corresponding to a formation planned region of the compound region 42 (the deepest compound region 42 in FIG. 2) is formed. can get. here,
The mask layer 7 is patterned so that the mask material layer remains two-dimensionally periodically.

Next, an element (for example, oxygen) for forming the compound region 42 is introduced as ions from the surface side of the silicon layer 3 on which the mask layer 7 is formed into the silicon layer 3 to form the compound region 42. By performing the compound region forming step described above, a structure as shown in FIG. 3C is obtained. Here, in the compound region formation step, an ion implantation step of introducing oxygen ions into the formation planned region of the compound region 42 at an acceleration voltage set so that oxygen ions can be introduced from the surface side of the silicon layer 3 through the mask layer 7 is performed. The number of arrangements of the compound regions 42 in the depth direction (the number of arrangements is 2 in the example of FIG. 1) is repeated a prescribed number of times, and
The acceleration voltage of oxygen ions is changed stepwise according to the depth position of the region where the compound region 42 is to be formed in the depth direction. More specifically, oxygen ions are applied from the surface side of the silicon layer 3 on which the mask layer 7 is formed at a first accelerating voltage set so as to form the deepest compound region 42 in the silicon layer as shown in FIG. The first ion implantation step of implanting along the direction of the arrow in FIG.
3 is obtained by forming 2 and the compound region 42 is located on the side closer to the surface of the silicon layer 3 by the above distance than the deepest compound region 42 which is lower than the first acceleration voltage. With a second accelerating voltage set so that the silicon layer 3 is formed along the direction of the arrow in FIG.
The photonic crystal 4 is formed by performing the second ion implantation step of implanting oxygen ions from the surface side of, to form the compound region 42, and the structure shown in FIG. 3C is obtained.
The dose amount of oxygen ions in each ion implantation step is set so that silicon oxide is formed in the region where the compound region 42 is to be formed. Further, each value of the first accelerating voltage and the second accelerating voltage is a value that allows oxygen ions to pass through the mask layer 7, and the compound region 42 is formed below the mask layer 7 in each ion implantation step. However, the compound region 42 below the mask layer 7 is
Is formed on the side closer to the surface of the silicon layer 3 by the amount corresponding to the thickness of the mask layer 7 than the compound region 42 below the opening. Further, although the acceleration voltage in the ion implantation step is decreased stepwise in the compound region forming step, the acceleration voltage may be increased stepwise. Further, as can be seen from the above description, the mask layer 7 has an ion implantation depth adjusting function for adjusting the implantation depth of oxygen ions.

After obtaining the structure shown in FIG. 3 (c), the mask layer 7 is removed to obtain the structure shown in FIG. 3 (d).

Next, a method of forming the above-mentioned grating 5 will be described with reference to FIG.

First, a mask material layer (for example, a resist layer) is formed on the surface of the silicon layer 3, and the compound region 51 is to be formed in a planned region by a lithography technique (photolithography technique or electron beam lithography technique). A structure shown in FIG. 4A is obtained by performing a mask layer forming step of forming a mask layer 8 having an opening in a portion. Here, the mask layer 8 is patterned so that the mask material layer is one-dimensionally periodically removed.

Next, an element (for example, oxygen) for forming the compound region 51 is introduced into the silicon layer 3 as an ion from the surface side of the silicon layer 3 on which the mask layer 8 is formed to form the compound region 51. By performing the compound region forming step described above, the grating 5 including a large number of compound regions 51 is formed, and a structure as shown in FIG. 4B is obtained. Here, in the compound region forming step, the thickness of the mask layer 8 is set so that the oxygen ions are implanted into the silicon layer 3 only through the openings of the mask layer 8. The implanted region 9 is formed.

After obtaining the structure shown in FIG. 4B, the mask layer 8 including the implantation region 9 is removed to obtain the structure shown in FIG.
The structure shown in is obtained.

A heat treatment for enhancing crystallinity may be performed after the above-mentioned ion implantation.

In the optical functional device of this embodiment, however, the photonic crystal 4 and the grating 5 are continuous with the optical waveguide (silicon layer 3), and the silicon region 41 and the compound region forming the photonic crystal 4 are combined. 42
Since the silicon region 41 is a part of the silicon layer 3 and the compound region 42 is formed by selectively oxidizing the silicon layer 3, the compound region 42 is continuous with the silicon layer 3 and the photonic The mechanical strength of the crystal 4 and the grating 5 is higher than in the conventional case, and the reliability is high. In short, the photonic crystal 4 and the grating 5 are formed in the silicon layer 3 by selectively forming the compound regions 42 and 51 in the silicon layer 3 which is the base layer using the lithography technique and the ion implantation technique. Therefore, the mechanical strength is higher and the reliability is higher than the conventional photonic crystal or grating. In other words, in the present embodiment, the photonic crystal 4 and the grating 5 are formed by using the ion implantation technique without etching the base layer 3 or forming the components of the photonic crystal on the base layer 3. Can be formed in the silicon layer 3 which is the base layer, the photonic crystal 4 and the grating 5 are continuous with the silicon layer 3, and the mechanical strength is higher than in the conventional case.
Higher reliability. Further, since the compound regions 42 and 51 are made of silicon oxide, they have high thermochemical stability. The optical functional element of the present embodiment can be manufactured using a so-called SOI wafer in which a silicon layer is formed on a silicon substrate with an insulating film made of a silicon oxide film interposed therebetween.

By the way, in the above embodiment, a photonic crystal having a three-dimensional periodic structure is adopted as the photonic crystal 4, but a photonic crystal having a two-dimensional periodic structure in a plane parallel to the surface of the silicon layer 3. May be adopted, and such a photonic crystal having a two-dimensional periodic structure can be formed by the same method as the method of forming the grating 5. In the above embodiment, the compound regions 42, 5
Although 1 is composed of silicon oxide, silicon nitride (Si ₃ N ₄ ) may be adopted instead of silicon oxide (the refractive index of silicon nitride is about 1.9). When the regions 42 and 51 are made of silicon nitride, nitrogen ions may be implanted into the silicon layer 3 instead of oxygen ions as the ions described in the above manufacturing method. Further, although the semiconductor substrate such as the silicon substrate is adopted as the substrate 1, a substrate other than the semiconductor substrate may be adopted. Further, the optical function element of the above embodiment includes the photonic crystal 4, the grating 5 and the light receiving element 6, but it is sufficient that at least one of the photonic crystal 4 and the grating 5 is provided.

[0043]

According to the first aspect of the present invention, a large number of compound regions which are made of a compound containing a constituent substance of the base layer and are selectively formed in the base layer and have a different refractive index from the base layer, and the compound in the base layer are included. A base region which is a region other than the region,
The compound regions are regularly arranged at intervals of about the wavelength of light propagating in the base layer, and the compound regions selectively formed in the base layer have a wavelength of light propagating in the base layer. Since they are regularly arranged at intervals, there is an effect that they can be used as an optical functional element having high mechanical strength and high reliability. The compound region is continuous with the base region by being selectively formed in the base layer.

According to a second aspect of the present invention, in the first aspect of the invention, the constituent material of the base region is silicon, and the constituent material of the compound region is silicon oxide or silicon nitride. This has the effect of improving stability.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the base region and the compound region are one-dimensionally arranged alternately at a period of about the wavelength of the light. Since it has, there is an effect that it can be used as an optical functional element having a grating having high mechanical strength and high reliability.

According to a fourth aspect of the present invention, there is provided the periodic structure according to the first or second aspect, wherein the base region and the compound region are two-dimensionally arranged alternately at a period of about the wavelength of the light. Therefore, there is an effect that it can be used as an optical functional element having a photonic crystal having a two-dimensional periodic structure with high mechanical strength and high reliability.

According to a fifth aspect of the invention, in the first or second aspect of the invention, a periodic structure is provided in which the base region and the compound region are three-dimensionally arranged alternately at a period of about the wavelength of the light. Since it has, there is an effect that it can be used as an optical functional element having a photonic crystal having a three-dimensional periodic structure with high mechanical strength and high reliability.

The invention of claim 6 is the method of manufacturing an optical functional element according to claim 3 or 4, wherein a site corresponding to the planned formation region of the compound region is opened on one surface of the base layer. And a mask layer forming step of forming a mask layer, and introducing an element for forming the compound region from the one surface side of the base layer on which the mask layer is formed into the base layer as ions. A lithography technique in which a photonic crystal having a grating or a two-dimensional periodic structure, which has high mechanical strength and high reliability, is used in a general semiconductor manufacturing process, since a compound region forming step of selectively forming a compound region is provided. There is an effect that it can be easily formed in the base layer by using the ion implantation technique.

According to a seventh aspect of the present invention, there is provided the method of manufacturing an optical functional element according to the fifth aspect, wherein a compound region farthest in the depth direction of the base layer is formed on one surface of the base layer. In the mask layer forming step of forming a mask layer having openings at corresponding portions, and in the substrate layer as an element for forming the compound region from the one surface side of the substrate layer having the mask layer formed as ions. A compound region forming step of forming a compound region by introducing the compound region into the compound region forming step, wherein in the compound region forming step, an element for forming the compound region is used as an ion from the one surface side of the base layer through the mask layer. The number of arrangements of the compound regions in the depth direction of the base layer is the ion implantation step of introducing the compound region into the region where the compound region is to be formed with an acceleration voltage set so that The mechanical strength is high and the reliability is high because the ion accelerating voltage is changed step by step according to the depth position of the region where the compound region is to be formed in the depth direction. There is an effect that a photonic crystal having a dimensional periodic structure can be easily formed by using a lithography technique and an ion implantation technique used in a general semiconductor manufacturing process. The number of cycles of the compound region in the depth direction of the base layer is equal to the specified number.

According to the invention of claim 8, in the invention of claim 7, in the compound region forming step, the accelerating voltage is reduced each time the ion implantation step is repeated, so that a photonic crystal having a three-dimensional periodic structure is formed. There is an effect that it can be formed in the base layer with good controllability.

According to a ninth aspect of the invention, in the seventh aspect of the invention, in the compound region forming step, the accelerating voltage is increased each time the ion implantation step is repeated, so that a photonic crystal having a three-dimensional periodic structure is formed. There is an effect that it can be formed in the base layer with good controllability.

[Brief description of drawings]

FIG. 1 is a schematic exploded perspective view showing an embodiment.

FIG. 2 is a schematic front view of the above.

FIG. 3 is a cross-sectional view of main steps for explaining the method for forming a photonic crystal in the above.

FIG. 4 is a cross-sectional view of main steps for explaining the method for forming a grating in the above.

FIG. 5 is a schematic perspective view of a photonic crystal showing a conventional example.

FIG. 6 is a schematic perspective view of a photonic crystal showing another conventional example.

FIG. 7 is an explanatory diagram of a method of forming a photonic crystal of the same.

[Explanation of symbols]

1 substrate 2 insulating film 3 Silicon layer 4 Photonic crystals 5 grating 6 Light receiving element 41 Silicon area 42 Compound area 51 Compound area

Claims (9)

[Claims] 1. A substrate comprising a large number of compound regions made of a compound containing a constituent material of the substrate layer and selectively formed in the substrate layer and having a refractive index different from that of the substrate layer, and a region other than the compound region in the substrate layer. And an area, and the compound area is regularly arranged at intervals of about a wavelength of light propagating through the base layer. 2. The optical functional device according to claim 1, wherein the constituent material of the base region is silicon, and the constituent material of the compound region is silicon oxide or silicon nitride. 3. The structure according to claim 1, wherein the base region and the compound region have a periodic structure in which they are one-dimensionally arranged alternately at a period of about the wavelength of the light.
The optical functional element described. 4. The structure according to claim 1 or 2, wherein the base region and the compound region have a periodic structure in which they are two-dimensionally arranged alternately at a period of about the wavelength of the light.
The optical functional element described. 5. The structure according to claim 1 or 2, wherein the base region and the compound region have a periodic structure in which they are three-dimensionally arranged alternately with a period of about the wavelength of the light.
The optical functional element described. 6. The method of manufacturing an optical functional element according to claim 3, further comprising a mask layer having an opening on a surface of the base layer, the portion corresponding to an area where the compound area is to be formed. A mask layer forming step to be formed, and an element for forming the compound region is introduced as ions from the one surface side of the substrate layer on which the mask layer is formed into the substrate layer to selectively select the compound region. And a compound region forming step of forming the optical function element. 7. The method for manufacturing an optical functional element according to claim 5, wherein a portion corresponding to a farthest compound region formation planned region in the depth direction of the base layer is opened on one surface of the base layer. And a mask layer forming step of forming a mask layer, and introducing an element for forming the compound region from the one surface side of the base layer on which the mask layer is formed into the base layer as ions. And a compound region forming step of forming a compound region, wherein in the compound region forming step, ions can be introduced from the one surface side of the base layer through the mask layer as an element for forming the compound region. The ion implantation step of introducing the compound region into the region where the compound region is to be formed with the set acceleration voltage is repeated a prescribed number of times which is the number of arrangement of the compound regions in the depth direction of the base layer. And a step of changing the accelerating voltage of the ions stepwise according to the depth position of the region where the compound region is to be formed in the depth direction. 8. The method of manufacturing an optical functional element according to claim 7, wherein in the compound region forming step, the accelerating voltage is reduced each time the ion implantation step is repeated. 9. The method of manufacturing an optical functional element according to claim 7, wherein in the compound region forming step, the acceleration voltage is increased each time the ion implantation step is repeated.