Method for producing photonic device, and photonic device

Abstract

The present invention reduces internal absorption of a photonic device. A method for producing a photonic device according to the present disclosure performs: a first step (step S30) in which a silicon (1) is processed by dry etching so as to obtain a specific shape (4); and a second step (step S50) in which a surface layer (4a) of the specific shape (4) is removed by chemical etching or thermal etching.

Description

Photonics device manufacturing method and photonics device

[0001] The present disclosure relates to a method for manufacturing a photonics device and to a photonics device.

[0002] Patent Document 1 and Non-Patent Document 1 relate to silicon photonic crystals provided with optical waveguides and optical resonators.

[0003] JP 2019-40046 (Published on March 14, 2019)

[0004] "Raman silicon laser based on a nanocavity fabricated by photolithography" Vol. 3, No. 4 / 15 April 2020 / OSA Continuum 814-823

[0005] The prior art leaves room for improvement in the internal absorption of photonic devices fabricated from silicon or silicon compounds.

[0006] A method for manufacturing a photonics device according to one aspect of the present disclosure includes a first step of processing silicon or a silicon compound by dry etching to obtain a specific shape, and a second step of removing the surface layer of the specific shape by chemical etching or thermal etching.

[0007] A photonics device according to one aspect of the present disclosure is a photonics device having a specific shape processed by dry etching from silicon or a silicon compound, wherein a surface layer up to 10 nm from the surface of the specific shape does not contain a substance that increases the light absorption of the photonics device.

[0008] A photonics device according to one aspect of the present disclosure is a photonics device having a specific shape processed by dry etching of silicon or a silicon compound, wherein the specific shape does not have a surface layer extending up to 10 nm from the surface immediately after the dry etching.

[0009] According to one aspect of the present disclosure, the internal absorption of a photonics device can be reduced compared to conventional devices. Specifically, it is expected that the experimental Q value of the resonator can be improved from 20,000 to 200,000.

[0010] 5 is a cross-sectional view showing an example of a method for manufacturing a photonic device according to an embodiment of the present disclosure; FIG. 6 is a plan view showing an example of a method for manufacturing the photonic device shown in FIG. 1; FIG. 7 is a plan view showing another example of a method for manufacturing the photonic device shown in FIG. 1; FIG. 8 is a cross-sectional view showing another example of a method for manufacturing the photonic device shown in FIG. 1; FIG. 9 is a plan view showing a configuration of a photonic device according to an experimental example of the present disclosure; FIG. 10 is an energy level diagram showing the photonic band structure of the heterostructure resonator shown in FIG. 5; FIG. 11 is a SEM photograph of the surface of a sample that has been cleaned 0 times according to an experimental example of the present disclosure; FIG. 12 is a SEM photograph of the surface of a sample that has been cleaned 12 times according to an experimental example of the present disclosure; FIG. 13 is a graph of Q values ​​according to experimental examples and comparative examples of the present disclosure; FIG. 14 is a perspective view showing an example of the configuration of a photonic device according to an embodiment of the present disclosure; FIG. 15 is a cross-sectional view showing an example of a method for manufacturing a photonic device according to an embodiment of the present disclosure.

[0011] (Miller plane index) In this disclosure, the mirror plane index is used to identify a crystal plane. That is, the unit cell vector a １ , a ２ , a ３ and using integers h, k, and l, 1 / h*vector a １ , 1 / k*vector a ２ , 1 / l × vector a ３ The crystal plane passing through the three points specified by is called the (hkl) plane. The (hkl) plane and planes equivalent to the (hkl) plane are collectively called the (hkl)-equivalent planes.

[0012] [Embodiment 1] (Manufacturing Method) Figures 1 and 2 are cross-sectional and plan views illustrating an example of a manufacturing method for a photonics device according to one aspect of the present disclosure. As shown in Figures 1 and 2, first, silicon 1 or a silicon compound is prepared (step S10). The silicon compound includes, for example, silicon nitride, silicon oxide, or silicon oxynitride. Figure 1 illustrates an example of preparing a top silicon layer of an SOI substrate as silicon 1, and in this disclosure, the same reference numeral "1" is used for both silicon and the top silicon layer. The SOI substrate includes a silicon support substrate, a buried silica layer 2 on the silicon support substrate, and a top silicon layer 1 on the buried silica layer 2.

[0013] Next, a mask layer 3 is formed on the silicon 1 or silicon compound, and the mask layer 3 is patterned using photolithography, electron beam lithography, nanoimprinting, or the like (step S20). The silicon 1 or silicon compound is then processed by dry etching to obtain a specific shape 4 (step S30, "first step"). Dry etching includes, for example, plasma etching. The specific shape 4 may include, for example, one or more of a plurality of holes in a photonic crystal, an optical waveguide, and a ring optical resonator. Optical waveguides include silicon wires, silicon compound wires, rib-type waveguides, and other optical waveguides in general. FIG. 1 shows an example in which the specific shape 4 is a plurality of holes; in this disclosure, the same reference numeral "4" is used for both the specific shape and the plurality of holes. By dry etching, a substance 5 (so-called "impurities" or "surface impurities") is added to the specific shape 4. Such substance 5 typically increases the light absorption of photonic devices. The provision of substance 5 to specific shape 4 means that, when specific shape 4 is voids 4, substance 5 is provided to the silicon 1 or the remaining silicon compound after the formation of voids 4. In the present disclosure, when understanding by replacing "specific shape 4" with "voids 4," please understand that "specific shape 4" should be appropriately replaced with "silicon 1 or the remaining silicon compound after the formation of voids 4."

[0014] The substance 5 that increases light absorption includes, for example, substances that are used as etching gases for silicon 1 or silicon compounds and as gases added to etching gases, such as fluorine, sulfur, boron, chlorine, bromine, iodine, oxygen, hydrogen, carbon, argon, helium, and xenon. The substance 5 may include multiple types of substances, and in this case, the concentration of the substance 5 is the sum of the concentrations of the multiple types of substances.

[0015] Next, the mask layer 3 is removed (step S40), and the surface layer 4a of the specific shape 4 is removed by chemical etching or thermal etching (step S50, "second process"). The chemical etching or thermal etching in step S50 is a technique for removing the surface layer 4a in nanometer units. Step S50 is repeated as necessary to remove the surface layer 4a to a desired depth. At least a portion of the substance 5 imparted to the specific shape 4 by dry etching in step S30 can be removed by chemical etching or thermal etching in step S50. It should be noted that in this disclosure, a distinction is made between a "surface" and a "surface layer." A "surface" does not have a depth (i.e., thickness). On the other hand, a "surface layer" is a layer that has a depth up to a given distance from the surface.

[0016] In step S50, the surface layer 4a may be oxidized and the oxide film removed by chemical etching. The method for oxidizing the surface layer 4a is a method other than heat treatment that heats the specific shape 4 itself. Such heating of the object itself is intended to clean the surface of the object or reduce surface defects. Methods for oxidizing the surface layer 4a include, for example, a method using a high-temperature, high-humidity oxygen atmosphere and a method using a room-temperature oxidizing solution such as SPM (sulfuric acid-hydrogen peroxide mixture). The oxide film may be removed by cleaning with dilute hydrofluoric acid, phosphoric acid solution, or nitric acid solution. A method that combines oxidation in a high-temperature oxygen atmosphere and removal of the oxide film by chemical etching is called "thermal etching." Alternatively, in step S50, the surface layer 4a may be directly removed by chemical etching without oxidizing it. Using an alkaline solution such as dilute potassium hydroxide solution, silicon can be wet-etched with nanometer precision at room temperature without oxidation. It should be noted that no heat treatment is performed between steps S30 and S50 to heat the SOI substrate or the specific shape 4. It should be noted that the heat treatment referred to here is different from an exposure treatment in which an object is exposed to a high-temperature atmosphere.

[0017] 3 is a plan view showing another example of a method for manufacturing the photonic device shown in FIG. 3. As shown in FIG. 3, the specific shape 4 is a plurality of holes 4 in a photonic crystal. When the opening shape of the holes 4 is formed to be circular by dry etching, the opening shape of the holes 4 can be expanded to an octagon by chemical etching or thermal etching. However, the specific shape 4 may be deformed by chemical etching or thermal etching. This deformation may depend on the crystal structure and plane orientation of the silicon 1 or silicon compound.

[0018] The (111)-equivalent plane of silicon is difficult to etch with many etching solutions and thermal etching. Therefore, the opening shape of the void 4 is easily deformed by chemical etching or thermal etching after dry etching so that the edges extend along the (111)-equivalent plane. The (111)-equivalent planes in silicon include eight planes: the (111) plane, the (-111) plane, the (1-11) plane, the (-11-1) plane, the (1-1-1) plane, the (-11-1) plane, and the (-1-1-1) plane. The aforementioned octagonal shape is a shape in which four edges appear along the (111), (-111), (1-11), and (-1-11)-planes, which are difficult to etch, by performing chemical etching or thermal etching on the circular opening shape initially formed by dry etching. Further etching may result in four adjacent difficult-to-etch surfaces intersecting with each other, resulting in four intersecting sides, forming a rectangular opening shape for the hole 4. Depending on the opening shape formed by the initial dry etching, subsequent chemical or thermal etching may result in a variety of other shapes. Regardless of the shape, the opening shape of the hole 4 tends to have at least one side aligned with one of the four planes: the (111), (−111), (1-11), and (−1-11). Hole shapes based on a similar mechanism can also be obtained with substrates having other surface orientations, such as (110) silicon substrates, and substrates having off-planes. Etching solutions that increase the etching rate of the difficult-to-etch surface relative to the etching rate of other surfaces are also commercially available, and hole shapes based on a similar mechanism can also be obtained using such etching solutions.

[0019] Fig. 4 is a cross-sectional view showing another example of a method for manufacturing the photonics device shown in Fig. 1. As shown in Fig. 4, the substance 5 may be distributed so that the closer to the top surface (upper part in Fig. 4), the more the substance 5 is present, or the layer thickness of the substance 5 is greater. Then, chemical etching or thermal etching is performed to sufficiently remove the substance 5 near the top surface.

[0020] 1 and 2, the specific shape 4 is then washed with pure water (step S60). Step S60 may be repeated together with step S50 as necessary.

[0021] According to the manufacturing method of the present disclosure, the surface layer 4a to which the substance 5 has been applied can be removed to obtain the specific shape 4 having a fresh surface layer 6. Therefore, according to the manufacturing method of the present disclosure, the internal absorption of the photonics device can be reduced by removing the surface impurities from the specific shape 4. The reduction in internal absorption can increase the effective Q value of the optical resonator and reduce the propagation loss of the optical waveguide.

[0022] (Configuration) The photonics device according to the present disclosure is a photonics device fabricated by the manufacturing method according to the present disclosure. The manufacturing method according to the present disclosure can form photonic crystals, optical waveguides, and ring optical resonators with reduced surface impurities. However, it is impractical to directly identify these by their structure or properties.

[0023] Known techniques for measuring the composition or impurities of a substance include absorption spectroscopy, EDX (Energy Dispersive X-ray spectroscopy), cathodoluminescence, and SIMS (Secondary ion mass spectrometry). However, it is impossible to limit the measurement range of these techniques to the wall surface of holes with a diameter of about several hundred nanometers or the side surface of an optical waveguide or optical resonator because the wall or side of these microstructures is not flat. Combining impurity measurement using these techniques with confirmation of the measurement range using a scanning electron microscope (SEM) is conceivable, but this is not practical due to the high cost involved, the difficulty of working on the minute side of an optical waveguide, etc., and the technical difficulty of combining the devices with high precision.

[0024] Furthermore, surface impurities are believed to be present inside the surface layer due to dry etching. For example, the inventors found that impurities (substances that increase light absorption in photonics devices) implanted into the substrate by plasma etching exist within a depth range of 5 nm to 10 nm from the surface as a result of repeated chemical etching of the surface layer and subsequent Q-value measurements. For this reason, it is impossible to observe surface impurities even by observing the sample surface, and as mentioned above, it is impossible to measure the layer thickness where the surface impurities exist.

[0025] It is beneficial for the chemical etching or thermal etching in step S50 to remove the surface layer 4a, particularly the surface layer 4c of the sidewall, to a depth sufficient to remove surface impurities. According to the above findings, the substance 5 implanted into the substrate by plasma etching exists within a depth range of 5 nm to 10 nm from the surface. Under these conditions, good results were obtained experimentally when removing the substance from the surface to a depth in the range of 5 nm to 15 nm. Therefore, when the dry etching in step S30 is plasma etching, it is beneficial to remove the substance from the surface of the specific shape 4 to a depth in the range of 5 nm to 15 nm by the chemical etching or thermal etching in step S50. It is also beneficial to remove the substance from the surface of the specific shape 4 to a depth in the range of 5 nm to 10 nm.

[0026] It should be understood that the depth range suitable for removal in step S50 varies depending on the conditions for performing step S30 and the design specifications of the specific shape 4. For example, it is expected that the thickness of the layer containing surface impurities can be reduced by changing or improving the type and conditions of dry etching. In such a case, it is beneficial to remove the surface impurities to a depth of several nanometers or more from the surface. The lower limit of the depth range suitable for removal may be 2 nm or 3 nm. Furthermore, for example, in a design specification in which the specific shape 4 is thick or the voids 4 are deep, it is expected that the thickness of the layer containing surface impurities due to dry etching will be large. This includes the case in which the surface impurities are more abundant closer to the top surface, as shown in FIG. 4 . In such a case, it is beneficial to remove the surface impurities to a depth of several tens of nanometers or less from the surface. The upper limit of the depth range suitable for removal may be 20 nm or 30 nm.

[0027] The depth removed by chemical etching or thermal etching (hereinafter referred to as "etching depth") may have errors depending on the location. Errors may also occur in the measurement of the etching depth. It is useful to determine the etching depth taking such errors into consideration.

[0028] The etching depth can be measured by various methods. For example, when the etching rate is known, the etching depth may be calculated as the product of the etching rate and the time for which chemical etching is performed. For example, in a plan view, the aperture radius of the holes in the photonic crystal, or the linewidth of an optical waveguide or ring optical resonator, may be measured before and after chemical etching, and the etching depth may be calculated as half the difference in aperture radius or linewidth. The aperture radius is the radius of a circle having the same area as the aperture area of ​​the aperture being measured. The aperture areas may be calculated for multiple apertures and their average value may be taken.

[0029] As described above, chemical etching or thermal etching may deform the specific shape 4 depending on the crystal structure of the silicon 1 or silicon compound. It is useful to determine the etching depth taking such deformation into consideration. For example, if the opening shape of the holes 4 is uniformly expanded from a circle to a regular octagon, it is useful to determine the etching depth so that the distance between the center of the side of the regular octagon and the circle matches the depth that can sufficiently remove surface impurities.

[0030] The photonics device according to the present disclosure is a photonics device having a specific shape 4 fabricated by dry etching from silicon 1 or a silicon compound, wherein a surface layer 6 up to 10 nm from the surface of the specific shape 4 does not contain a material 5 that increases the light absorption of the photonics device. It should be noted that in the present disclosure, a distinction is made between the surface layer 4a immediately after dry etching (i.e., before chemical or thermal etching) and the surface layer 6 after chemical or thermal etching.

[0031] The concentration of the substance 5 in the surface layer 6 is estimated, and the estimated value is 10 １６ [ / cm ３ ] less than 10 １５ [ / cm ３], the surface layer 6 can be considered to be substantially free of the substance 5. Depending on the manufacturing method and / or the resulting configuration of the photonics device, a concentration measurement region where the surface concentration of the substance 5 can be measured may naturally occur within the photonics device. Furthermore, during the fabrication of the photonics device, a separate member having a concentration measurement region can be simultaneously formed on the same substrate. In the concentration measurement region, the concentration of each substance contained in the surface layer can be measured by absorption spectroscopy, EDX (Energy Dispersive X-ray spectroscopy), cathodoluminescence, SIMS (Secondary ion mass spectrometry), or the like. The surface concentration in the specific shape 4 can be estimated based on the measurement of the surface concentration in the concentration measurement region. A configuration that is substantially free of the substance 5 that increases optical absorption is effective in general optical resonators such as heterostructure resonators and ring resonators, as well as in general optical waveguides such as silicon wire waveguides, silicon compound wire waveguides, rib-type waveguides, and heterostructure waveguides.

[0032] The photonics device according to the present disclosure is a photonics device having a specific shape 4 processed by dry etching of silicon 1 or a silicon compound, in which a surface layer 4a up to 10 nm thick has been removed from the surface of the specific shape 4 immediately after dry etching.

[0033] The specific shape 4 may be a plurality of holes 4 in the photonic crystal, and the opening shape of the holes 4 may be circular. Alternatively, the opening shape of the holes 4 may be octagonal.

[0034] Experimental Example 1 In fabricating a photonic device 10 according to Experimental Example 1 of the present disclosure, the top silicon layer 1 of an SOI substrate was processed by plasma etching to form multiple voids 4 in a photonic crystal (step S30, "first step"). Next, the mask layer 3 was removed (step S40), and the surface layer 4b on the top surface of the remaining top silicon layer 1 and the surface layer 4c on the sidewalls of the multiple voids 4 were removed by one or more SPM cleanings and dilute hydrofluoric acid cleanings (step S50, "second step"). Hereinafter, in this disclosure, a photonic device before SPM cleaning will be referred to as a "zero-cleaned sample." Furthermore, a photonic device that has undergone n SPM cleanings and dilute hydrofluoric acid cleanings will be referred to as an "n-cleaned sample," where n is a natural number. Note that another solution, such as a phosphoric acid solution or a nitric acid solution, may be used instead of dilute hydrofluoric acid.

[0035] FIG. 5 is a plan view showing the configuration of a photonics device according to an experimental example. As shown in FIG. 5, the photonics device 10 according to experimental example 1 includes a two-dimensional photonic crystal in which a plurality of voids 4 are regularly formed in silicon 1, and includes a defect region as a heterostructure resonator 20 in which voids 4 are not formed linearly in the x direction. The photonics device 10 includes a first region A1, a second region A2, a third region A3, a fourth region A4, and a fifth region A5, arranged in this order in the x direction. The center-to-center distances of the voids 4 were designed to be 410 nm in the first region A1 and the fifth region A5, 415 nm in the second region A2 and the fourth region A4, and 420 nm in the third region A3. The radius of the voids 4 in the sample that had not undergone SPM cleaning was designed to be 122 nm.

[0036] Fig. 6 is an energy level diagram showing the photonic band structure of the heterostructure resonator shown in Fig. 5. As shown in Fig. 6, a gap barrier was generated between the regions depending on the difference in the center-to-center distance of the air holes 4, and two nanoresonator modes (excitation mode and Stokes mode) were formed. The experimental Q value of the excitation mode was calculated for each sample cleaned 2, 3, 6, 9, and 12 times according to Experimental Example 1.

[0037] The radius of the pores 4 of each sample was calculated based on a photograph taken by a scanning electron microscope (SEM). Specifically, for each sample, the opening areas of three pores 4 in the SEM photograph were measured, the radii of circles having the same area as each opening area were calculated, and the average value of these radii was taken as the radius of the pores 4.

[0038] Fig. 7 is a view showing an SEM photograph of the surface of a sample washed 0 times according to Experimental Example 1. Fig. 8 is a view showing an SEM photograph of the surface of a sample washed 12 times according to Experimental Example 1. As shown in Figs. 7 and 8, the opening shape of the pores 4 was approximately circular in the sample washed 0 times, while it was approximately octagonal in the sample washed 12 times. The difference in the radius of the pores 4 between the sample washed 0 times and the sample washed 12 times was approximately 10 nm.

[0039] (Experimental Examples 2 to 7) Photonic devices according to Experimental Examples 2 to 7 were fabricated on the same substrate and in the same process as the photonic device according to Experimental Example 1. Therefore, the fabrication precision of Experimental Examples 2 to 7 was the same as that of Experimental Example 1. The photonic devices according to Experimental Examples 2 to 7 were designed to have the same configuration as the photonic device 10 according to Experimental Example 1, except for the radius of the air holes 4. The radius of the air holes 4 according to Experimental Examples 2 to 7 was designed so that the radius of the air holes 4 in the samples according to Experimental Examples 2 to 7 that had not been washed once increased stepwise in the range of 125 nm to 132 nm.

[0040] The experimental Q value of the excitation mode was calculated for each sample that had been cleaned two, three, six, nine, and twelve times in Experimental Examples 2 to 7. The radius of the air holes 4 for each sample was calculated based on SEM photographs. (Comparative Example 1) Various photonic crystals including heterostructure resonators with air hole 4 radii ranging from 125 nm to 132 nm were hypothetically designed, and the design Q values ​​of the excitation light when excitation light of various wavelengths was incident on the resonators were calculated while ignoring internal absorption.

[0041] 9 is a graph showing the Q value for Experimental Examples 1 to 7 and Comparative Example 1. The vertical axis on the left side of FIG. 9 represents the experimental Q value (Q p_exp ) and the value on the scale is read by multiplying it by the power of 10. The vertical axis on the right side of FIG. 9 shows the design Q value (Q p_des) and the scale value is read by multiplying it by 10 to the power of 6. The horizontal axis in FIG. 9 is common to both the experimental Q value and the design Q value, and represents the resonant wavelength (λ p ) is shown.

[0042] The points for the samples of Experimental Examples 1-7 are indicated by solid symbols, and the points for Comparative Example 1 are indicated by open symbols. For Examples 1-7, the points for the samples washed twice are indicated by circles, the points for the samples washed three times are indicated by squares, the points for the samples washed six times are indicated by triangles pointing up, the points for the samples washed nine times are indicated by triangles pointing down, and the points for the samples washed twelve times are indicated by diamonds.

[0043] 9, when comparing samples with the same number of cleaning cycles, the larger the radius of the holes 4, the shorter the resonant wavelength and the smaller the experimental Q value. Since the fabrication precision of Experimental Examples 1 to 7 was the same, it was presumed that the wavelength dependency of the experimental Q value was due to absorption loss inside the sample.

[0044] When comparing samples according to the same experimental example, it was found that the more times the samples were washed, in other words, the larger the radius of the holes 4, the shorter the resonant wavelength and the larger the experimental Q value.

[0045] When comparing samples with the same or similar resonant wavelengths, samples that were washed more frequently tended to have higher experimental Q values ​​than samples that were washed fewer times. More specifically, the experimental Q value did not improve significantly after two or fewer washes, but improved significantly after three, six, nine, and 12 washes. Figures 6 and 7 clearly show that repeated cleaning causes the shape of the air holes 4 to deviate from the design. On the other hand, repeated cleaning removes surface impurities, which cause absorption loss. While deviations decrease the design Q value, the effect of removing surface impurities outweighs this, resulting in an improvement in the experimental Q value. Furthermore, in some experimental examples, cleaning was performed 13 or more times, but the shape of the air holes 4 deviated so significantly from the design that it was impossible to determine any improvement in the experimental Q value.

[0046] Second Embodiment For convenience of explanation, components having the same functions as those described in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0047] 10 is a perspective view showing an example of the configuration of a photonics device according to one embodiment of the present disclosure. As shown in FIG. 10, the specific shape 4 may include a ring resonator 41. And / or the specific shape may include a wire waveguide 42. The wire waveguide 42 is a silicon wire or a silicon compound wire. The ring resonator 41 and the wire waveguide 42 are embossed from the silicon or silicon compound by dry etching, and the surface layer is removed by chemical etching or thermal etching.

[0048] The specific shape 4 is not limited thereto, and may include at least one type of optical waveguide selected from the group consisting of a silicon wire waveguide, a silicon compound wire waveguide, a rib-type waveguide, and a heterostructure waveguide. In the present disclosure, the specific shape 4 may refer to a portion embossed from the silicon compound as shown in FIG. 10 , or to a portion recessed into the silicon compound as shown in FIGS. 1 to 5 . In either case, as shown in FIGS. 1 and 4 , the substance 5 is more likely to penetrate deeply into the side surface layer 4 c than into the top surface layer 4 b. Therefore, regardless of whether the specific shape 4 is a recessed portion or a recessed portion, the depth to which the surface layer 4 a of the specific shape 4 is removed depends on the penetration depth of the substance 5 into the side surface layer 4 c. [Embodiment 3]

[0049] 11 is a cross-sectional view illustrating an example of a method for manufacturing a photonics device according to an aspect of the present disclosure. As shown in FIG. 11, step S40 may be performed after step S50.

[0050] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present disclosure also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments. The specific shape in the present disclosure may include optical resonators such as air holes, heterostructure resonators, and ring resonators, optical waveguides such as thin-wire waveguides, rib-type waveguides, and heterostructure waveguides, as well as any shape that can exhibit optical functions.

[0051] [Summary] The method for manufacturing a photonics device according to aspect 1 of the present disclosure is a method that includes a first step of processing silicon or a silicon compound by dry etching to obtain a specific shape, and a second step of removing a surface layer of the specific shape by chemical etching or thermal etching.

[0052] A method for manufacturing a photonics device according to aspect 2 of the present disclosure may be the manufacturing method described in aspect 1, in which at least a portion of the material imparted to the specific shape by the dry etching is removed by the chemical etching or the thermal etching.

[0053] A method for manufacturing a photonics device according to aspect 3 of the present disclosure may be the manufacturing method described in aspect 1 or 2, in which the dry etching is plasma etching, and the chemical etching or thermal etching removes the material from the surface of the specific shape to a depth in the range of 2 nm to 30 nm.

[0054] A method for manufacturing a photonics device according to aspect 4 of the present disclosure may be the method according to any one of aspects 1 to 3, in which the dry etching is plasma etching, and the chemical etching or thermal etching removes the material from the surface of the specific shape to a depth in the range of 5 nm to 15 nm.

[0055] A method for manufacturing a photonics device according to aspect 5 of the present disclosure may be the method described in any one of aspects 1 to 4, in which the dry etching is plasma etching, and the chemical etching or thermal etching removes material from the surface of the specific shape to a depth in the range of 5 nm to 10 nm.

[0056] The method for manufacturing a photonics device according to aspect 6 of the present disclosure may be a manufacturing method according to any one of aspects 1 to 5, in which a heat treatment for heating the specific shape is not performed between the first step and the second step.

[0057] A method for manufacturing a photonics device according to aspect 7 of the present disclosure may be the manufacturing method described in any one of aspects 1 to 6, in which the specific shape is a plurality of voids in a photonic crystal, the dry etching is plasma etching, the chemical etching is cleaning with any of dilute hydrofluoric acid, phosphoric acid solution, and nitric acid solution, the plurality of voids are formed by the plasma etching, and the surface layer of the sidewalls of the plurality of voids is removed by the cleaning.

[0058] A method for manufacturing a photonics device according to aspect 8 of the present disclosure may be the manufacturing method described in any one of aspects 1 to 7, wherein the specific shape is a plurality of voids in a photonic crystal, and the opening shape of the voids is formed into a circular shape by the dry etching, and the opening shape of the voids is expanded to an octagon by the chemical etching or the thermal etching.

[0059] A manufacturing method for a photonics device according to aspect 9 of the present disclosure may be the manufacturing method described in any one of aspects 1 to 8, wherein the specific shape is a plurality of voids in a photonic crystal, and the plurality of voids are formed regularly so as to have a defect region where voids are not formed in a straight line.

[0060] A method for manufacturing a photonics device according to aspect 10 of the present disclosure may be the method according to any one of aspects 1 to 6, in which the specific shape is a ring resonator.

[0061] A method for manufacturing a photonics device according to an eleventh aspect of the present disclosure may be the method according to any one of the first to sixth aspects, wherein the specific shape includes at least one type of optical waveguide selected from the group consisting of a silicon wire waveguide, a silicon compound wire waveguide, a rib waveguide, and a heterostructure waveguide.

[0062] A photonics device according to aspect 12 of the present disclosure is a photonics device having a specific shape processed by dry etching from silicon or a silicon compound, wherein a surface layer up to 10 nm from the surface of the specific shape does not contain a substance that increases the light absorption of the photonics device.

[0063] A photonics device according to aspect 13 of the present disclosure is a photonics device having a specific shape processed by dry etching of silicon or a silicon compound, wherein the specific shape does not have a surface layer extending up to 10 nm from the surface immediately after the dry etching.

[0064] A photonics device according to aspect 14 of the present disclosure may have the configuration described in aspect 12 or 13, wherein the specific shape is a plurality of holes in a photonic crystal, and the opening shape of the holes is circular.

[0065] A photonics device according to aspect 15 of the present disclosure may have the configuration described in aspect 12 or 13, wherein the specific shape is a plurality of holes in a photonic crystal, and the opening shape of the holes is octagonal.

[0066] A photonics device according to aspect 16 of the present disclosure may have the configuration described in aspect 12 or 13, wherein the specific shape is a plurality of holes in a photonic crystal, and the opening shape of the holes is rectangular.

[0067] A photonics device according to aspect 17 of the present disclosure may have the configuration described in aspect 12 or 13, wherein the specific shape is a plurality of holes in a photonic crystal, and the opening shape of the holes may have at least one side along any of four faces: a (111) plane, a (−111) plane, a (1-11) plane, and a (−1-11) plane.

[0068] A photonics device according to aspect 18 of the present disclosure may be configured as described in any one of aspects 12 to 17, wherein the specific shape is a plurality of voids in a photonic crystal, the plurality of voids are regularly formed, and the photonic crystal includes a defect region where voids are not formed in a straight line.

[0069] A photonics device according to Aspect 19 of the present disclosure may have the configuration described in Aspect 12 or 13, wherein the specific shape is a ring resonator.

[0070] A photonics device according to Aspect 20 of the present disclosure may have the configuration described in Aspect 12 or 13, and the specific shape may include at least one type of optical waveguide selected from the group consisting of a silicon wire waveguide, a silicon compound wire waveguide, a rib waveguide, and a heterostructure waveguide.

[0071] REFERENCE SIGNS LIST 1 Silicon, top silicon layer 4 Specific shape, void 4a Surface layer (immediately after dry etching) 4c Surface layer of sidewall 5 Material 6 Surface layer 10 Photonics device 41 Ring resonator 42 Wire waveguide

Claims

1. a first step of processing silicon or a silicon compound by dry etching to obtain a specific shape; a second step of removing the surface layer of the specific shape by chemical etching or thermal etching to a depth in the range of 2 nm to 30 nm from the surface of the specific shape.

2. The method according to claim 1 , wherein at least a portion of the material imparted to the specific shape by the dry etching is removed by the chemical etching.

3. The manufacturing method according to claim 1 or 2, wherein the dry etching is plasma etching.

4. the dry etching is plasma etching, The manufacturing method according to claim 1 or 2, wherein the chemical etching removes the specific shape from the surface to a depth in the range of 5 nm to 15 nm.

5. the dry etching is plasma etching, The manufacturing method according to claim 1 or 2, wherein the chemical etching removes the specific shape from the surface to a depth in the range of 5 nm to 10 nm.

6. The manufacturing method according to claim 1 or 2, wherein a heat treatment for heating the specific shape is not performed between the first step and the second step.

7. the specific shape is a plurality of holes in a photonic crystal; the dry etching is plasma etching, The chemical etching is cleaning with any one of diluted hydrofluoric acid, phosphoric acid solution, and nitric acid solution; The manufacturing method according to claim 1 , wherein the plurality of holes are formed by the plasma etching, and the surface layer of the sidewalls of the plurality of holes is removed by the cleaning.

8. a first step of processing silicon or a silicon compound by dry etching to obtain a specific shape; a second step of removing the specific shaped surface layer by chemical etching or thermal etching; the specific shape is a plurality of holes in a photonic crystal; The opening shape of the hole is formed into a circular shape by the dry etching, The method for manufacturing a photonics device further comprises expanding the opening shape of the hole into an octagon by the chemical etching or the thermal etching.

9. the specific shape is a plurality of holes in a photonic crystal; The manufacturing method according to claim 1 or 2, wherein the plurality of voids are formed regularly so that there are defect regions where no voids are formed in a straight line.

10. The manufacturing method according to claim 1 or 2, wherein the specific shape is a ring resonator.

11. The method according to claim 1 or 2, wherein the specific shape includes at least one type of optical waveguide selected from the group consisting of a silicon wire waveguide, a silicon compound wire waveguide, a rib-type waveguide, and a heterostructure waveguide.

12. (delete)

13. A photonics device having a specific shape processed by dry etching in silicon or a silicon compound, The photonics device has no surface layer up to 10 nm from the surface immediately after the dry etching in the specific shape.

14. the specific shape is a plurality of holes in a photonic crystal; The photonics device according to claim 13 , wherein the opening shape of the hole is circular.

15. the specific shape is a plurality of holes in a photonic crystal; The photonics device according to claim 13 , wherein the opening shape of the hole is octagonal.

16. the specific shape is a plurality of holes in a photonic crystal; The photonics device according to claim 13 , wherein the opening shape of the hole is rectangular.

17. the specific shape is a plurality of holes in a photonic crystal; 14. The photonics device according to claim 13, wherein the opening shape of the hole has at least one side along any one of four planes: a (111) plane, a (-111) plane, a (1-11) plane, and a (-1-11) plane.

18. the specific shape is a plurality of holes in a photonic crystal; the plurality of pores are regularly formed, The photonics device of claim 13 , wherein the photonic crystal includes a defect region in which voids are not formed in a straight line.

19. The photonics device of claim 13 , wherein the particular shape is a ring resonator.

20. 14. The photonics device of claim 13, wherein the specific shape comprises at least one optical waveguide selected from the group consisting of a silicon wire waveguide, a silicon compound wire waveguide, a rib waveguide, and a heterostructure waveguide.

21. the specific shape is a plurality of holes in a photonic crystal; the dry etching is plasma etching, The thermal etching is a method that combines oxidation in a high-temperature oxygen atmosphere with removal of an oxide film by cleaning with any one of diluted hydrofluoric acid, phosphoric acid solution, and nitric acid solution; The manufacturing method according to claim 1 or 2, wherein the plurality of voids are formed by the plasma etching, and the surface layers of the side walls of the plurality of voids are removed by the oxidation and the cleaning.