JP2007175891A - Substrate resin laminated structure and optical waveguide module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the joining strength between a resin layer and a substrate by using an intermediate layer of a new structure in a substrate resin laminated structure in which the resin layer is laminated on the surface of the substrate such as a Si substrate. <P>SOLUTION: A surface-modified film 15 (SiO<SB>2</SB>heat-oxidized film) is formed on the surface of the Si substrate 12 by heat oxidation etc. At least one oxidized film 16 (SiOx film) is formed on the surface-modified film 15 by a spatter or CVD, and the resin layer is formed on the oxidized film 16. The density of the oxidized film 16 is greater than that of the surface-modified film 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate resin laminate structure and an optical waveguide module. Specifically, in a substrate resin laminate structure in which a resin layer is laminated on the surface of a substrate such as a Si substrate, the bonding strength between the resin layer and the substrate is increased. It relates to technology to improve.

  In various technical fields, a substrate resin laminated structure in which a resin layer is laminated and integrated on the surface of a Si substrate is used, but it is difficult to obtain a bonding strength between the resin layer and the Si substrate. Therefore, in order to obtain the bonding strength between the resin layer and the Si substrate, it is common to provide an intermediate layer to ensure adhesion.

  On the other hand, it is generally known that a thermal oxide film (silicon oxide film) becomes an extremely strong adhesion film with respect to a Si substrate. However, as described in Patent Document 1 and the like, the thermal oxide film cannot provide high adhesion to the resin layer. In particular, in the case of an optical waveguide module in which an optical waveguide is bonded on a Si substrate, fluorine is mixed into the optical waveguide made of acrylic resin to improve the performance of the optical waveguide. Precipitation prevents the optical waveguide and the Si substrate from sticking to each other. For this reason, it has been difficult to obtain the bonding strength between the Si substrate and the optical waveguide.

  Therefore, as an intermediate layer between the resin layer and the Si substrate, generally, a coupling agent containing organic zirconium, titanium oxide or the like is used, or a resin not containing fluorine is used. Or both may be used together.

  However, when a coupling agent containing organic zirconium, titanium oxide, or the like is used as the intermediate layer, as described in Patent Document 2, particles included in the coupling agent are used as the starting point for the intermediate layer. As a result, cracks and spots grew, and peeling of the intermediate layer spread from the particle position, so that a strong adhesion film could not be obtained. In order to prevent this, particles contained in the coupling agent must be removed through a filter or the like, which has the disadvantage that the number of steps increases and it is difficult to completely remove the particles.

  When a resin containing no fluorine is used as the intermediate layer, the adhesion is improved, but the adhesion is still insufficient. Further, when the intermediate layer is formed using a resin not containing fluorine, it is difficult to accurately control the coating thickness of the resin, and thus it is difficult to make the intermediate layer have a desired thickness. Furthermore, when the surface of the Si substrate is uneven, a resin not containing fluorine cannot be uniformly applied to the surface of the convex portion of the Si substrate by a normal process. In addition, when a component such as an optical component is placed thereon, when alignment and positioning are required on the submicron order, alignment and positioning cannot be performed, and uniform adhesion cannot be obtained.

  For example, when a resin that does not contain fluorine is applied to the surface of the Si substrate with a spin coater that is most commonly used, the thickness of the coating film is controlled even if the rotational speed, time, temperature, resin viscosity, etc. are strictly controlled. It varies. In addition, when the coating film is multilayered, the error is further increased and the thickness variation is further increased. In the spin coating method, only a small portion of the resin solution used is applied to the Si substrate, and most of the resin solution is discarded without forming a coating film, so that the consumption of the resin solution is large. Therefore, the waste of the resin used as the intermediate layer is large and the cost loss is large.

Japanese Patent Laid-Open No. 2001-100055 JP 2005-75978 A

  The present invention has been made in view of the technical problems as described above. The object of the present invention is to provide a substrate resin laminate structure in which a resin layer is laminated on the surface of a substrate such as a Si substrate, and has a novel structure. The intermediate layer is used to improve the bonding strength between the resin layer and the substrate.

  The first substrate resin laminated structure according to the present invention has a surface modified film formed by surface modification on the surface of the substrate, and the surface modified film formed by deposition on the surface modified film. At least one oxide film having a low density is formed, and a resin layer is formed on the oxide film. The oxide film is a film containing an oxide, and may be a mixture of an oxide and another substance (for example, a nitride). Further, when the density of the oxide film changes in the thickness direction, the density of the upper surface of the oxide film in contact with the resin layer may be lower than the density of the surface modified film. The resin layer can be any resin such as a thermosetting resin, an ultraviolet curable resin, or a room temperature curable resin. If necessary, a resin layer may be formed after applying a primer or the like on the oxide film.

  As a result of intensive studies, the inventors of the present invention have conceived that the adhesion between the resin layer and the intermediate layer is a problem of the number of OH groups that contribute to bonding. That is, when the density of the intermediate layer is high, the ratio of molecules to each other and the OH group bond is reduced, but when the density of the intermediate layer is low, the number of molecules that stick to each other is reduced and the OH group remains. There are more bonds. In addition, when the density is high, only OH groups on the surface of the film appear, but when the density is low, the packing rate of molecules becomes small, so that OH groups inside the film also appear outside and become easy to bond.

  The first substrate resin laminated structure of the present invention is made based on this knowledge, and an oxide film having a lower density than the surface modified film is formed on the surface modified film. More OH group bonds appear in the oxide film than in the surface-modified film. For this reason, the OH group of the oxide film and the OH group of the resin layer (or, if a primer or the like is applied, an OH group such as a primer may be easily reacted) between the oxide film and the resin layer. Gives strong adhesion. In addition, the surface modification film is also firmly formed on the surface of the substrate, and the oxide film is formed on the surface modification film with strong adhesion as an energized deposition film. It can be bonded onto the substrate with strong adhesion.

  In one embodiment of the first substrate resin laminate structure of the present invention, the oxide film is formed in two or more layers, and any two of these oxide films are located on the side closer to the substrate The density of the oxide film located on the far side from the substrate is lower than that of the substrate. In such an embodiment, since the density of the oxide film is increased on the surface modification film side, the number of molecules that the oxide film and the surface modification film are bonded by chemical bonds increases, and the oxide film and the surface modification are increased. Adhesion with the film increases. On the other hand, since the density of the oxide film is small on the resin layer side, bonds due to OH groups are easily generated in the oxide film, and the resin layer can be bonded more firmly.

  In another embodiment of the first substrate resin laminated structure of the present invention, the oxide film is formed of two or more layers, and the oxide film adjacent to the resin layer is formed more than the oxide film adjacent to the surface modification film. The density is lower. Even in such an embodiment, since the density of the oxide film is increased on the surface modified film side, the number of molecules that the oxide film and the surface modified film are bonded by chemical bonds increases, and the oxide film and the surface modified film increase. Adhesion with the film increases. On the other hand, since the density of the oxide film is small on the resin layer side, bonds due to OH groups are easily generated in the oxide film, and the resin layer can be bonded more firmly. Even if the density of the intermediate oxide film is not particularly a problem, the oxide films have strong adhesion even if the densities are different.

  In still another embodiment of the first substrate resin laminated structure of the present invention, the density of the oxide film gradually decreases from the side closer to the substrate toward the side farther from the substrate. In this case, the oxide film may be a mixture or compound of an oxide and another substance, and the composition ratio of the oxide and the other substance may be gradually changed. Even in such an embodiment, since the density of the oxide film is increased on the surface modified film side, the number of molecules that the oxide film and the surface modified film are bonded by chemical bonds increases, and the oxide film and the surface modified film increase. Adhesion with the film increases. On the other hand, since the density of the oxide film is small on the resin layer side, bonds due to OH groups are easily generated in the oxide film, and the resin layer can be bonded more firmly.

  According to still another embodiment of the first substrate resin laminated structure of the present invention, the density of the oxide film changes in a direction perpendicular to the surface of the substrate, and the oxide film is more dense than a region adjacent to the surface modified film. The density is lower in the region adjacent to the resin layer. Even in such an embodiment, since the density of the oxide film is increased on the surface modified film side, the number of molecules that the oxide film and the surface modified film are bonded by chemical bonds increases, and the oxide film and the surface modified film increase. Adhesion with the film increases. On the other hand, since the density of the oxide film is small on the resin layer side, bonds due to OH groups are easily generated in the oxide film, and the resin layer can be bonded more firmly. Even if the density of the intermediate oxide film is not particularly a problem, the oxide films have strong adhesion even if the densities are different.

  In the second substrate resin laminated structure of the present invention, a surface modified film by surface modification is formed on the surface of the substrate, and OH is more effective than the surface modified film formed by deposition on the surface modified film. At least one oxide film having a large number density of groups is formed, and a resin layer is formed on the oxide film. By forming an oxide film having a lower number density of OH groups than the surface modified film, the adhesion between the oxide film and the resin layer can be improved, and the resin layer can be firmly bonded onto the substrate.

  In one embodiment of the second substrate resin laminate structure of the present invention, the oxide film is formed in two or more layers, and any two of these oxide films are located on the side closer to the substrate The number density of OH groups is higher in the oxide film located farther from the substrate than in the substrate. In such an embodiment, the number of molecules in which the oxide film and the surface modified film are bonded by chemical bonds increases, and the adhesion between the oxide film and the surface modified film increases. On the other hand, bonds due to OH groups are easily generated in the oxide film on the resin layer side, and the resin layer can be bonded more firmly.

  In another embodiment of the second substrate resin laminate structure of the present invention, two or more oxide films are formed, and an oxide film adjacent to the resin layer is formed rather than an oxide film adjacent to the surface modification film. However, the number density of OH groups is larger. In such an embodiment, the number of molecules in which the oxide film and the surface modified film are bonded by chemical bonds increases, and the adhesion between the oxide film and the surface modified film increases. On the other hand, bonds due to OH groups are easily generated in the oxide film on the resin layer side, and the resin layer can be bonded more firmly.

  In another embodiment of the second substrate resin laminated structure according to the present invention, the oxide film has a gradually increasing number density of OH groups from a side closer to the substrate to a side farther from the substrate. In such an embodiment, the number of molecules in which the oxide film and the surface modified film are bonded by chemical bonds increases, and the adhesion between the oxide film and the surface modified film increases. On the other hand, bonds due to OH groups are easily generated in the oxide film on the resin layer side, and the resin layer can be bonded more firmly.

  In another embodiment of the second substrate resin laminate structure of the present invention, the density of the oxide film changes in a direction perpendicular to the surface of the substrate, and more than a region adjacent to the surface modification film, The region adjacent to the resin layer has a higher number density of OH groups. In such an embodiment, the number of molecules in which the oxide film and the surface modified film are bonded by chemical bonds increases, and the adhesion between the oxide film and the surface modified film increases. On the other hand, bonds due to OH groups are easily generated in the oxide film on the resin layer side, and the resin layer can be bonded more firmly.

As the substrate in the first or second substrate resin laminated structure of the present invention, a Si substrate can be used. In this case, a silicon compound such as SiO ₂ , SiOx, SiC, or SiN can be used as the surface modification film. As the oxide film, a metal oxide film such as SiOx, TiOx, or AlOx can be used. Further, as a means for depositing an oxide film on the surface modification film, a deposition method such as sputtering, CVD, or vapor deposition can be used. According to a deposition method such as sputtering, CVD, or vapor deposition, many OH groups having activity in the oxide film are generated. Of these, sputtering and CVD methods may produce a large number of OH groups having activity especially in the oxide film.

  As a board | substrate in the 1st or 2nd board | substrate resin laminated structure of this invention, metal substrates, such as Ti board | substrate and Al board | substrate, can be used. In this case, a metal oxide film such as TiOx or AlOx, a metal carbide film, or a metal nitride film can be used as the surface modification film. As the oxide film, a metal oxide film such as SiOx, TiOx, or AlOx can be used. Further, as a means for depositing an oxide film on the surface modification film, a deposition method such as sputtering, CVD, or vapor deposition can be used. According to a deposition method such as sputtering, CVD, or vapor deposition, many OH groups having activity in the oxide film are generated. Of these, sputtering and CVD methods may produce a large number of OH groups having activity especially in the oxide film.

  Still another embodiment of the first or second substrate resin laminated structure of the present invention is that the surface of the substrate and / or the surface of the surface modification film and / or the surface of the oxide film is rough. It is a feature. As a method for roughening the surface, etching or sand blasting may be used, and the roughness is preferably about several μm to 1 μm. In such an embodiment, since the surface of the substrate and / or the surface of the surface modification film and / or the surface of the oxide film is rough, the surface area is increased and the micro anchor effect is added between the substrate and the surface modification film. In addition, the adhesion between the surface modification film and the oxide film or between the oxide film and the resin layer can be further improved. At this time, if only the lower layer such as the substrate is roughened, the roughness of the film on the top layer is reduced although the roughness is reduced. Therefore, a certain effect can be obtained without making each layer rough.

  Still another embodiment of the first or second substrate resin laminated structure of the present invention is characterized in that irregularities exist on the surface of the substrate. In such an embodiment, the unevenness is formed on the surface of the substrate and the surface area is increased, so that the adhesion between the substrate and the surface modification film can be further enhanced. Furthermore, since the uneven shape is reproduced or duplicated in the shape of the surface modification film or oxide film formed on the surface, the adhesion between the surface modification film and the oxide film, and between the oxide film and the resin layer. Can be further enhanced. In addition to this, each layer of the substrate with irregularities is slightly roughened by etching or sandblasting to further increase the surface area and between the substrate and the surface modified film by the micro-anchor effect. The adhesion between the oxide film and the resin layer can be further increased between the films. At this time, if only the lower layer such as the substrate is roughened, the roughness of the film formed thereon is reduced but the roughness is reproduced. Therefore, a certain effect can be obtained without making each layer rough.

  Yet another embodiment of the first or second substrate resin laminate structure of the present invention is characterized in that the resin layer contains fluorine. When the resin layer is an optical component, particularly an optical waveguide, the optical performance can be improved by adding fluorine to the resin. However, if fluorine is included in the resin layer, the adhesion between the oxide film and the resin layer may be lowered. However, according to the present invention, sufficient adhesion is achieved even when the resin layer contains fluorine. Sex can be obtained.

  Still another embodiment of the first or second substrate resin laminated structure of the present invention is characterized in that the surface modification film and the oxide film are composed of the same element. In such an embodiment, since the surface modification film and the oxide film are composed of the same element, chemical bonding is easy, and adhesion between the surface modification film and the oxide film is further improved.

  In addition, in the board | substrate resin laminated structure of this invention, a metal substrate can also be used as a board | substrate. When a metal substrate is used, AlOx (aluminum oxide), AlN (aluminum nitride), TiOx (titanium oxide), TiN (titanium nitride), TiC (titanium carbide) are used as surface modification films formed thereon. Oxides, nitrides, carbides, etc. can be used.

  An optical waveguide module according to the present invention includes a surface modified film formed by surface modification on a surface of a substrate, and an oxide film having a lower density than the surface modified film formed by deposition on the surface modified film Is characterized in that at least one layer is formed, and an optical waveguide formed of resin is bonded onto the oxide film. Such an optical waveguide module is obtained by applying the configuration of the first substrate resin laminated structure of the present invention to the optical waveguide module, and therefore the optical waveguide can be firmly bonded on the substrate.

  In addition, the component demonstrated above of this invention can be combined arbitrarily as much as possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments described below, an optical waveguide module will be described as an example. However, the present invention is not limited to the optical waveguide module, and can be widely used at the junction between the substrate and the resin layer.

  FIG. 1 is a side view of an optical waveguide module 11 showing an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. As shown in FIG. 2, an optical waveguide fixing surface 13 is formed at the center of the upper surface of the substrate 12 made of Si, and optical fiber fixing surfaces 14 are formed at both ends of the upper surface. A surface modification film 15 is formed on the surfaces of the optical waveguide fixing surface 13 and the optical fiber fixing surface 14, and an oxide film 16 is further formed thereon.

  One or a plurality of optical fiber positioning grooves 18 each having a V-groove shape for positioning the optical fiber 17 are provided in parallel to the longitudinal direction of the substrate 12 in both the optical fiber fixing surfaces 14. Between the optical waveguide fixing surface 13 and the optical fiber fixing surface 14, a concave groove 19 is formed on the upper surface of the substrate 12. As shown in FIG. 1, the cross-sectional shape of the concave groove 19 is inclined obliquely when viewed from the side surface direction.

  The optical waveguide 20 is obtained by embedding an optical waveguide core 22 formed of a core resin having a refractive index higher than that of the upper cladding portion 21 in an upper cladding portion 21 made of a transparent cladding resin. A lower clad portion 23 is formed of the same resin having the same refractive index as that of the upper clad portion 21 on the lower surfaces of 21 and the optical waveguide core 22. The optical waveguide core 22 has a structure according to purposes such as signal multiplexing, demultiplexing, synthesis, and branching, and the end faces of the optical waveguide core 22 are exposed at both end faces of the optical waveguide 20. The optical waveguide 20 is mounted on the optical waveguide fixing surface 13 with the lower cladding portion 23 side bonded to the oxide film 16. At this time, the optical fiber positioning groove and the core are precisely aligned and positioned. As the cladding resin, a transparent resin such as an acrylic resin containing fluorine is used. Moreover, as this resin, even if it is resin other than an acrylic resin, what is necessary is just a resin which has OH group. Even in the case of a resin having no OH group, it can be used by applying a primer or the like on the oxide film 16.

  Each optical fiber 17 is positioned in the horizontal direction and the vertical direction by fitting into the optical fiber positioning groove 18, and positioned so that the core center of the optical fiber 17 coincides with the center of the end face of the optical waveguide core 22. Has been. The optical fiber 17 fitted in the optical fiber positioning groove 18 is accommodated in a recess 24 provided on the lower surface of the cover plate 25 and is pressed from above by the cover plate 25. The cover plate 25 is bonded to the optical fiber 17 and the oxide film 16 on the optical fiber fixing surface 14 using an adhesive 26. The adhesive 26 is an adhesive resin that does not contain fluorine. Note that the optical fiber 17 may be bonded to the substrate 12 only by the adhesive 26 without using the cover plate 25. At this time, even an adhesive having no OH group can be used by applying a primer or the like on the oxide film 16. Further, an adhesive containing fluorine may be used.

FIG. 3 is an enlarged view schematically showing a portion X in FIG. 1 and shows a joint portion between the substrate 12 and the optical waveguide 20. A surface modification film 15 made of SiOx is formed on the surface of the substrate 12 made of Si. The surface modification film 15 may be a SiOx film formed by thermally oxidizing the surface of the substrate 12, or may be a film in which oxygen ions are irradiated on the surface of the substrate 12 to implant oxygen ions. Such surface modified film 15, SiO ₂ film is not structurally stable, since good adhesion to the substrate 12 is obtained, SiO ₂ film is particularly desirable. Therefore, in the following, the case of the surface modification film 15 made mainly of SiO ₂ film will be described, but the surface modification film 15 made of SiO ₂ film can be replaced with the surface modification film 15 made of SiO x film. . An oxide film 16 is formed on the surface modification film 15 by depositing SiOx by a deposition method such as sputtering, CVD, or vapor deposition.

The film thickness t1 of the surface modification film 15 may be 0.005 μm ≦ t1 ≦ 3 μm. In a normal state, the natural oxide film has a film thickness of only about 0.001 μm (= 10 mm), and there are many defects, and sufficient adhesion cannot be obtained. However, the film thickness t1 of the surface modification film 15 is 0.005 μm. If it is set to (= 50 mm) or more, the surface-modified film 15 can be stably formed with few defects using a general apparatus. Further, if the film thickness t1 of the surface modification film 15 is 3 μm or less, it can be produced by a general apparatus, and a thermal oxide film can be produced without being damaged. Further, the thickness t1 of the surface modification film 15 is particularly preferably 0.05 μm ≦ t1 ≦ 0.5 μm, even within the above range. In a method using thermal oxidation or the like that is often used because the surface modified film 15 can be obtained by a simple process, a stable SiO ₂ film can be formed if the film thickness t1 is 0.05 μm (= 500 mm) or more. If the film thickness is less than this, the Si-rich composition is obtained, the molecular structure becomes non-uniform, and the adhesiveness varies, thereby reducing the adhesiveness with the oxide film 16. Further, if the film thickness t1 is 0.5 μm or less, the surface modified film 15 can be formed in a time without any problem in actual production, and the film formation cost can be reduced.

  The film thickness t2 of the oxide film 16 may be 0.022 μm <t2 ≦ 2 μm. If the thickness t2 of the oxide film 16 is smaller than 0.022 μm (= 220 mm), the oxide film 16 may be island-shaped, but if it is 0.022 μm or more, the oxide film 16 can be formed in layers. It is. Further, if the thickness t2 of the oxide film 16 is larger than 2 μm, the oxide film 16 may be broken by the stress of the film itself. Therefore, the thickness of the oxide film 16 is preferably 2 μm or less. further. The film thickness t2 of the oxide film 16 is particularly preferably 0.05 μm ≦ t2 ≦ 1 μm in the above range. This is because if the thickness t2 of the oxide film 16 is 0.05 μm (= 500 mm) or more, the oxide film 16 can be formed in a layered manner covering the entire surface of the surface modification film 15 even when the surface has irregularities such as roughness. . Further, if the thickness t2 of the oxide film 16 is 1 μm or less, the oxide film 16 can be formed in a time that does not cause a problem in actual production, and the film formation cost can be reduced.

The oxide film 16 has a density (weight density) lower than that of the surface modification film 15, and the element filling rate is considerably smaller than that of the surface modification film 15. The value of x in SiOx that is the oxide film 16 is not particularly limited, and may be, for example, x = 2, but many OH groups appear in SiOx (1 ≦ x ≦ 1.5), especially SiO _1.3. As described later, the adhesion between the oxide film 16 and the resin layer (lower clad portion 23) can be increased. As the density ratio of the surface modification film 15 and the oxide film 16, a ratio of less than 1 to 0.60 for the oxide film 16 with respect to the surface modification film 15 is better because adhesion strength can be obtained. In this case for example Si, density surface modification layer 15 is 2.6~2.15g / cm ^3, the oxide film 16 may be a 2.15~1.6g / cm ^3. Further, at this time, if the density ratio is 0.95 or more, it is more preferable because it is possible to realize adhesion with a higher reliability level suitable for outdoor use. As the refractive index ratio, the value of the surface modification film 15 is 1 and the ratio of the oxide film 16 of less than 1 to 0.89 is better because the adhesion strength can be obtained. At this time, for example, in the case of SiO ₂ , the surface modification film 15 may be in the range of 1.475 to 1.460, and the oxide film 16 may be in the range of 1.460 to 1.320. Further, at this time, if the same refractive index ratio is 0.99 or more, it is further preferable because it is possible to realize adhesion with a higher reliability level suitable for outdoor use.

  In mounting the optical waveguide 20 on the optical waveguide fixing surface 13, after forming the optical waveguide core 22 in the recess of the upper cladding portion 21, a cladding resin is dropped on the oxide film 16 of the substrate 12, The upper cladding portion 21 and the optical waveguide core 22 are superimposed on the optical waveguide fixing surface 13 and pressed with the surface where the optical waveguide core 22 is exposed facing down. Next, the lower cladding portion 23 is formed by spreading a cladding resin between the upper cladding portion 21 and the optical waveguide core 22 and the oxide film 16, and the optical waveguide 20 is bonded onto the oxide film 16. At this time, in consideration of the type of resin to be used, if necessary, a primer or the like may be applied on the oxide film for mounting in order to improve adhesion. In addition, if the resin for cladding does not contain fluorine, it is more preferable because stronger adhesion can be obtained.

In such a structure, since the surface of the substrate 12 on which the surface modification film 15 is formed is chemically changed and strongly bonded to the surface modification film 15, the substrate 12 and the surface modification film 15 are good. Adhesion is obtained, and the surface modification film 15 is not peeled off from the substrate 12. Further, since the oxide film 16 is formed on the surface modified film 15 as a deposit (deposited film) given energy by sputtering, CVD or the like, the surface modified film 15 and the oxide film 16 are sufficiently formed. A strong chemical bond is obtained. Moreover, since the surface modification film 15 (SiO ₂ film) and the oxide film 16 (SiOx film) are composed of the same element, they are easily chemically bonded and are higher than when the oxide film 16 is directly formed on the substrate 12. Adhesion can be obtained.

  When the density of the film is high, the ratio of molecules to each other and OH group bonds decreases, but when the film density is low, the number of molecules that stick to each other decreases and the remaining bonds of OH groups are reduced. Become more. In addition, when the density is high, only OH groups on the surface of the film appear, but when the density is low, the packing rate of molecules becomes small, so that OH groups inside the film also appear outside and become easy to bond. Incidentally, it was also confirmed from experimental data that the adhesiveness improved as the density decreased. Therefore, if the density of the oxide film 16 is lower than the density of the surface modification film 15 as in the first embodiment, many OH group bonds appear, and therefore, the OH group of the oxide film 16 and the optical waveguide 20 easily reacts with the OH group of the resin constituting the resin 20 (OH group and OH group react to become -O-), and strong adhesion is obtained between the oxide film 16 and the optical waveguide 20. . In particular, in order to improve the optical performance of the optical waveguide 20, the oxide film 16, the optical waveguide 20, and the optical waveguide 20, particularly even when fluorine is contained in the resin constituting the upper cladding portion 21 and the lower cladding portion 23, Strong adhesion can be obtained. Therefore, according to such a configuration, strong adhesion is obtained between the substrate 12 and the surface modification film 15, between the surface modification film 15 and the oxide film 16, and between the oxide film 16 and the optical waveguide 20. The optical waveguide 20 can be mounted on the substrate 12 with strong adhesion so that peeling does not occur.

  In addition, any or all of the surface of the substrate 12, the surface modification film 15, and the oxide film 16 may be roughened by etching or sandblasting. The roughness of the rough surface is preferably about several μm to 1 μm. If these surfaces are roughened, in addition to increasing the surface area, the micro-anchor effect can further enhance the adhesion with the members thereon (that is, the surface modification film 15, the oxide film 16, and the lower cladding part 23). . If the lower layer of the substrate or the like is roughened, the roughness of the layer above it is reduced but the roughness is reproduced. Therefore, a certain effect can be obtained without roughening each layer.

  FIG. 4 is an enlarged view schematically showing a Y portion in FIG. 1, and shows a joint portion between the substrate 12 and the cover plate 25. This joining portion has the same configuration as the joining portion between the substrate 12 and the optical waveguide 20 shown in FIG. Therefore, for the same reason as the bonding between the substrate 12 and the optical waveguide 20, any one of the substrate 12 and the surface modification film 15, the surface modification film 15 and the oxide film 16, or the oxide film 16 and the adhesive 26 is selected. However, a strong adhesion can be obtained, and the adhesive 26 can be adhered onto the substrate 12 with a strong adhesion so that peeling does not occur. Furthermore, since the adhesive 26 not containing fluorine is used at this location, the adhesive force between the adhesive 26 and the oxide film 16 is greater than the adhesive force between the optical waveguide 20 and the oxide film 16. The cover plate 25 may be made of a material that has good adhesiveness with the adhesive 26, and the cover plate 25 may be omitted.

  Therefore, according to the optical waveguide module 11 of Example 1, the optical waveguide 20 and the optical fiber 17 can be firmly mounted on the substrate 12, and the reliability of the optical waveguide module 11 can be improved. Even if the adhesive used at this time contains fluorine, there is no problem because sufficient adhesion can be obtained.

The oxide film 16 formed on the surface modification film 15 is preferably made of the same material as the substrate 12 and the surface modification film 15, and particularly preferably SiOx by sputtering having many bonds with OH groups. However, different materials such as TiOx and AlOx (especially Al ₂ O ₃ ) may be used as long as they have OH groups. Even in the case of a material different from the substrate 12 or the like, the adhesion force is higher when the oxide film 16 is formed on the surface modification film 15 (SiO ₂ ) than when the oxide film 16 is directly formed on the substrate 12.

  FIG. 5 is a sectional view schematically showing a joint structure used in the optical waveguide module according to the second embodiment of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

In Example 2, a surface modification film 15 (SiO ₂ film) is formed on the upper surface of a substrate 12 made of Si by thermal oxidation or the like, two oxide films 16a and 16b are formed thereon, and a resin is formed thereon. Layer 27 is bonded. Here, the resin layer 27 is the optical waveguide 20 or the adhesive 26 of the first embodiment, and for the sake of simplicity, the optical waveguide 20 and the adhesive 26 are collectively represented by the resin layer 27 hereinafter. To do.

  The lower oxide film 16a in contact with the surface modification film 15 and the upper oxide film 16b in contact with the resin layer 27 are both formed by sputtering, but the upper oxide film 16b is on the lower side. The density (weight density) is lower than that of the oxide film 16a. According to such a configuration, since the lower oxide film 16a has a relatively high density, it is easy to chemically bond with the surface modified film 15, and the adhesion between the surface modified film 15 and the oxide film 16a is increased. Further, since the upper oxide film 16b has a relatively low density, the number of bonds of OH groups that are bonded to the resin layer 27 is increased, and the unevenness of the oxide film 16b is increased, whereby the adhesion between the oxide film 16b and the resin layer 27 is increased. Becomes larger. Of course, since the oxide film 16a and the oxide film 16b differ only in density, they have high adhesion.

  Therefore, according to the second embodiment, the adhesive strength of the resin layer 27 to the substrate 12 is increased and the resin layer 27 is less likely to be peeled off, and the optical waveguide 20 and the optical fiber 17 are more firmly mounted on the substrate 12. The reliability of the optical waveguide module 11 can be improved.

FIG. 6 shows a modification of the second embodiment, in which three or more oxide films (SiOx) are stacked on the surface modification film 15 made of SiO ₂ . If these oxide films are an oxide film 16a, an oxide film 16b, an oxide film 16c, and an oxide film 16d in order from the lower layer, these oxide films 16a, 16b, 16c, and 16d have different densities from each other (the lowermost oxide film). Except for 16a and the uppermost oxide film 16d, the partial density may be the same. If the density of the oxide films 16a, 16b, 16c, and 16d is n1, n2, n3, and n4, the density is preferably
n1>n2>n3> n4
It has become. However, if n1> n4, the adhesion between the surface modification film 15 and the oxide film 16a and the adhesion between the oxide film 16d and the resin layer 27 can be improved, so that the intermediate oxide films 16b and 16c can be improved. The density may be arbitrary. For example,
n2>n1>n3> n4
It does not matter if it is.

  FIG. 7 is a cross-sectional view schematically showing the joint structure used in the optical waveguide module according to Example 3 of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

In Example 3, a surface modification film 15 (SiO ₂ film) is formed on the upper surface of a substrate 12 made of Si by thermal oxidation or the like, an oxide film 16 is formed thereon by sputtering, and a resin layer 27 is formed thereon. It is joined. The density of the oxide film 16 changes in the thickness direction, and the density decreases gradually or stepwise from the lower surface side to the upper surface side.

  Also in Example 3, since the density of the oxide film 16 is high on the lower surface side, it is easy to chemically bond with the surface modified film 15 and the adhesion between the surface modified film 15 and the oxide film 16 is increased. In addition, since the oxide film 16 has a low density on the upper surface side, the number of bonds of OH groups that are bonded to the resin layer 27 is increased and the unevenness of the oxide film 16 is increased, so that the adhesion between the oxide film 16 and the resin layer 27 is increased. growing.

  Therefore, according to the third embodiment, the bonding strength of the resin layer 27 to the substrate 12 is further increased and the resin layer 27 is hardly peeled off, and the optical waveguide 20 and the optical fiber 17 are more firmly mounted on the substrate 12. The reliability of the optical waveguide module 11 can be improved.

  Also in the third embodiment, the density of the oxide film 16 is not limited to the case where the density gradually decreases from the lower surface side toward the upper surface side. If the density of the oxide film 16 on the side adjacent to the resin layer 27 is smaller than the density of the oxide film 16 on the side adjacent to the surface modification film 16, what is the density of the oxide film 16 in the middle thereof? It does not matter if it changes.

  FIG. 8 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 4 of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

  In Example 4, a surface modification film 15 made of a nitride film (SiN) is formed on the surface of a substrate 12 made of Si. The surface modification film 15 may be a film in which a nitride film is formed on the surface of the substrate 12 by heating the substrate 12 in a nitrogen gas atmosphere, or nitrogen ions are implanted into the surface of the substrate 12 by irradiation with a nitrogen ion beam. It may be.

  The oxide film 16 is a mixture (SiN / SiOx) or compound (SiN1-xOx) of SiOx and another substance (in this case, SiN), and the composition ratio of both substances gradually changes in the thickness direction. That is, the density of the oxide film 16 is lower than the density of the surface modification film 15, the composition of SiOx is gradually increased from the lower surface side to the upper surface side, and the composition of SiN is increased from the lower surface side to the upper surface side. It gradually gets smaller as you go to. The lower surface of the oxide film 16 in contact with the surface modification film 15 is SiN, and the upper surface of the oxide film 16 in contact with the resin layer 27 is SiOx.

  Since it is well known that the nitride film (SiN) formed on the surface of the Si substrate is chemically bonded and firmly adhered to the surface of the Si substrate, the surface modification film 15 is also formed on the substrate 12 in Example 4. Adhere firmly. However, since the surface modification film 15 of the nitride film does not emit OH groups, the composition of the oxide film 16 is gradually changed from the nitride film to the oxide film from the lower side to the upper side. I try to put it out. Therefore, since the surface modification film 15 and the lower surface of the oxide film 16 are the same material, they are firmly adhered. Further, since the density of the oxide film 16 is lower than the density of the surface modification film 15, the number of bonds due to OH groups increases on the upper surface of the oxide film 16, and the adhesion between the upper surface of the oxide film 16 and the resin layer 27 is also improved. Get higher. As described above, when different materials are used for the surface modification film and the oxide film, the density of the oxide film is lower than that of the surface modification film because the density of the oxide film is lower than the density of the same type of surface modification film. Including. That is, comparing the high and low densities of different materials includes comparing with the density normalized by the density of the surface modification film in each material.

  Therefore, also in Example 4, the bonding strength of the resin layer 27 to the substrate 12 becomes larger and the resin layer 27 becomes difficult to peel off, and the optical waveguide 20 and the optical fiber 17 are more firmly mounted on the substrate 12. The reliability of the optical waveguide module 11 can be improved.

In Example 4 above, the surface modification film made of SiN was formed on the Si substrate (substrate 12). However, if it is on the Si substrate, silicon compound such as SiO ₂ or SiC is surface modified. A film may be formed. Further, a metal substrate such as a Ti substrate or an Al substrate may be used as the substrate 1, and in that case, a metal oxide such as TiOx or AlOx, a metal nitride such as TiN or AlN, TiC, or the like may be used as a surface modification film. It is also possible to form a metal carbide or the like on the substrate.

In particular, if the surface modification film is SiO ₂ , strong adhesion to the substrate and the oxide film can be obtained, and a semiconductor manufacturing process can be used, which is most preferable. Also, in this case, if the substrate is a Si substrate, it has good adhesion with the surface modification film, and it is easy to form SiO ₂ as the surface modification film, and the functional shape such as the fiber positioning groove with high accuracy by anisotropic etching. Is most desirable. Furthermore, even when the surface modification film is TiOx or AlOx, these are preferable because good adhesion to the substrate and the oxide film can be obtained. Further, when these surface modified films are used, if a Ti substrate or an Al substrate is used as the substrate, the surface modified film has good adhesion and can be formed easily.

  As the oxide film, SiOx is particularly desirable. The SiOx oxide film is most desirable because it provides strong adhesion to the surface modification film and the resin layer, and can be formed in the semiconductor manufacturing process. Next, an oxide film made of a metal oxide film such as TiOx or AlOx can also have good adhesion to the surface modified film and the resin layer.

  FIG. 9 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 5 of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

  In the fifth embodiment, a surface modification film 15 made of TiOx is formed on the upper surface of a substrate 12 made of Ti by thermal oxidation or the like. Further, an oxide film 16 made of TiOx deposited by sputtering or CVD is formed on the surface modification film 15. The oxide film 16 has a density lower than that of the surface modification film 15, and a resin layer 27 is bonded thereon.

  Even with such a structure, the surface modification film 15 by thermal oxidation or the like is firmly adhered to the substrate 12. Further, since the surface modification film 15 and the oxide film 16 are made of the same material and are deposited with energy when the oxide film 16 is deposited on the surface modification film 15, the surface modification film 15 and the oxide film 16 are also formed. Adhere firmly. Furthermore, since the density of the oxide film 16 is smaller than that of the surface modification film 15, more bonds are formed by OH groups than the surface modification film 15 on the surface side of the oxide film 16, so that the oxide film 16 is firmly bonded to the resin layer 27. To do.

  Therefore, also in Example 5, the bonding strength of the resin layer 27 to the substrate 12 becomes larger and the resin layer 27 becomes difficult to peel off, and the optical waveguide 20 and the optical fiber 17 are more firmly mounted on the substrate 12. The reliability of the optical waveguide module 11 can be improved.

  FIG. 10 is a sectional view showing a modification of the fifth embodiment. In this modification, SiOx having a lower density than that of the surface modification film 15 is used as the oxide film 16 in place of the TiOx of the fifth embodiment. Even if the oxide film 16 is made of SiOx, the adhesiveness is inferior to that of using the same kind of TiOx oxide film, but there is no problem with the adhesiveness with the surface modified film 15 made of TiOx. The optical waveguide 20 can be joined. In order to further increase the degree of adhesion, there is a method of obtaining the degree of adhesion by changing the composition ratio of SiOx and TiOx to eliminate the boundary as in Example 4, and this is still better in terms of adhesion.

  FIG. 11 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 6 of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

  In Example 6, the surface modification film 15 made of AlOx is formed on the upper surface of the substrate 12 made of Al by thermal oxidation or the like. Further, an oxide film 16 made of AlOx deposited by sputtering or CVD is formed on the surface modification film 15. The oxide film 16 has a density lower than that of the surface modification film 15, and a resin layer 27 is bonded thereon.

  Even with such a structure, the surface modification film 15 by thermal oxidation or the like is firmly adhered to the substrate 12. Further, since the surface modification film 15 and the oxide film 16 are made of the same material and are deposited with energy when the oxide film 16 is deposited on the surface modification film 15, the surface modification film 15 and the oxide film 16 are also formed. Adhere firmly. Furthermore, since the density of the oxide film 16 is smaller than that of the surface modification film 15, more bonds are formed by OH groups than the surface modification film 15 on the surface side of the oxide film 16, so that the oxide film 16 is firmly bonded to the resin layer 27. To do.

  Therefore, also in Example 6, the bonding strength of the resin layer 27 to the substrate 12 becomes larger and the resin layer 27 becomes difficult to peel off, and the optical waveguide 20 and the optical fiber 17 are more firmly mounted on the substrate 12. The reliability of the optical waveguide module 11 can be improved.

  FIG. 12 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 7 of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

  In Example 7, the unevenness 28 a is formed on the surface of the substrate 12. In this embodiment, since the unevenness 28a is formed on the surface of the substrate 12, the surface modification film 15 has the unevenness 28b, and the oxide film 16 has the unevenness 28c. Therefore, the surface areas of the substrate 12, the surface modification film 15 and the oxide film 16 can be increased by the irregularities 28a, 28b and 28c, whereby the substrate 12 and the surface modification film 15, the surface modification film and the oxide film, and the oxidation film. The adhesion between the film and the resin can be improved. In addition, if the surface of the substrate or film is roughened, the surface area can be further increased and the anchor effect can be obtained. Even in such a substrate, since the thickness of the surface modification film and the oxide film can be formed uniformly, the fiber positioning groove and the height of the core can be obtained even when the module as in Example 1 is formed on the substrate 12. Can be precisely aligned and positioned.

  FIG. 13 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 8 of the present invention. Since the structure of the optical waveguide module is the same as that shown in the first embodiment, the description is omitted, and only the junction structure is described.

  In Example 8, a reinforcing member 29 made of Si or glass is provided on the resin layer 27. When the reinforcing member 29 is attached to the upper surface, distortion during use can be reduced, so that stress is hardly generated at the film interface of each layer, and adhesion between the layers is further improved.

  The reinforcing member 29 preferably has the same thermal expansion coefficient as that of the substrate 12. If the reinforcing member 29 having the same thermal expansion coefficient as that of the substrate 12 is used, it is possible to prevent the substrate resin laminated structure from warping due to a change in ambient temperature.

  In each of the above embodiments, the density of the oxide film is lower than the density of the surface modified film. However, in the case of transparent materials having the same composition and the same composition ratio, the refractive index decreases as the density decreases. Therefore, it may be said that the oxide film has a refractive index smaller than that of the surface modified film. Thus, when different materials are used for the surface modification film and the oxide film, the refractive index of the oxide film is lower than that of the surface modification film because the density of the oxide film is the same (same composition, same composition ratio). It also includes lower than the refractive index of the surface modified film. That is, comparing the high and low refractive indices of different materials includes comparing the refractive index normalized with the refractive index of the surface modification film in each material.

  Further, a layer (film) for further improving the adhesion of the resin layer 27 may be formed between the upper surface of the oxide film 16 and the resin layer 27. For example, a coupling agent, a primer, etc. are mentioned. It goes without saying that such a case also falls within the scope of the present invention.

FIG. 1 is a side view of an optical waveguide module showing Embodiment 1 of the present invention. FIG. 2 is an exploded perspective view of the optical waveguide module according to the first embodiment. FIG. 3 is an enlarged view schematically showing a portion X in FIG. FIG. 4 is an enlarged view schematically showing a Y portion of FIG. FIG. 5 is a sectional view schematically showing a joint structure used in the optical waveguide module according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a modification of the second embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing the joint structure used in the optical waveguide module according to Example 3 of the present invention. FIG. 8 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 4 of the present invention. FIG. 9 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 5 of the present invention. FIG. 10 is a cross-sectional view illustrating a modification of the fifth embodiment. FIG. 11 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 6 of the present invention. FIG. 12 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 7 of the present invention. FIG. 13 is a cross-sectional view schematically showing a joint structure used in the optical waveguide module according to Example 8 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Optical waveguide module 12 Board | substrate 13 Optical waveguide fixed surface 14 Optical fiber fixed surface 15 Surface modification film | membrane 16 Oxide film 16a, 16b Oxide film 17 Optical fiber 18 Optical fiber positioning groove | channel 19 Concave groove 20 Optical waveguide 21 Upper clad part 22 Optical waveguide Core 23 Lower clad portion 24 Depression 25 Cover plate 26 Adhesive 27 Resin layer 28 Concavity and convexity 29 Reinforcing member

Claims (28)

  A surface modified film by surface modification is formed on the surface of the substrate, and at least one oxide film having a lower density than the surface modified film formed by deposition on the surface modified film is formed, A substrate resin laminated structure, wherein a resin layer is formed on an oxide film.   Two or more oxide films are formed, and any two of these oxide films have a density of an oxide film positioned farther from the substrate than an oxide film positioned closer to the substrate. The board | substrate resin laminated structure of Claim 1 characterized by the above-mentioned.   The oxide film adjacent to the resin layer is lower in density than the oxide film adjacent to the surface modification film, wherein two or more oxide films are formed. The board | substrate resin laminated structure of description.   2. The substrate resin laminated structure according to claim 1, wherein the oxide film has a density that gradually decreases from a side closer to the substrate toward a side farther from the substrate.   The density of the oxide film changes in a direction perpendicular to the surface of the substrate, and the density of the region adjacent to the resin layer is lower than the region adjacent to the surface modification film. The board | substrate resin laminated structure of Claim 1 characterized by the above-mentioned.   A surface modified film by surface modification is formed on the surface of the substrate, and at least one oxide film having a higher number density of OH groups than the surface modified film formed by deposition on the surface modified film is formed. A substrate resin laminate structure, characterized in that a resin layer is formed on the oxide film.   The oxide film is formed in two or more layers, and any two of the oxide films are formed such that the oxide film located on the side farther from the substrate is OH than the oxide film located on the side closer to the substrate. The board | substrate resin laminated structure of Claim 6 with which the number density of group is large.   The oxide film is formed in two or more layers, and the oxide film adjacent to the resin layer has a higher number density of OH groups than the oxide film adjacent to the surface modification film, The board | substrate resin laminated structure of Claim 6.   The substrate resin laminated structure according to claim 6, wherein the oxide film has a number density of OH groups gradually increasing from a side closer to the substrate to a side farther from the substrate.   The density of the oxide film changes in a direction perpendicular to the surface of the substrate, and the number density of OH groups is higher in the region adjacent to the resin layer than in the region adjacent to the surface modification film. The board | substrate resin laminated structure of Claim 6 characterized by the above-mentioned.   The board | substrate resin laminated structure of Claim 1 or 6 characterized by the above-mentioned.   The board | substrate resin laminated structure of Claim 1 or 6 characterized by the above-mentioned.   The substrate resin laminated structure according to claim 12, wherein the metal substrate is a Ti substrate or an Al substrate.   The substrate resin laminated structure according to claim 11, wherein the surface modified film is a silicon compound.   The substrate resin laminated structure according to claim 14, wherein the silicon compound is SiOx.   The substrate resin laminated structure according to claim 14, wherein the silicon compound is SiC or SiN. The substrate resin laminated structure according to claim 14, wherein the silicon compound is SiO ₂ .   14. The substrate resin laminated structure according to claim 13, wherein the surface modification film is a metal oxide film, a metal carbide film, or a metal nitride film.   The substrate resin laminated structure according to claim 18, wherein the metal oxide film as the surface modification film is TiOx or AlOx.   The board | substrate resin laminated structure of Claim 1 or 6 characterized by the above-mentioned.   The substrate resin laminate structure according to claim 1, wherein the oxide film is a metal oxide film.   The substrate resin laminated structure according to claim 21, wherein the metal oxide film as the oxide film is TiOx or AlOx.   The substrate resin laminated structure according to claim 1, wherein the oxide film is formed by a deposition method.   The substrate resin laminated structure according to claim 1 or 6, wherein the surface of the substrate and / or the surface of the surface modification film and / or the surface of the oxide film is rough.   The board | substrate resin laminated structure of Claim 1 or 6 with which the unevenness | corrugation exists in the surface of the said board | substrate.   The board | substrate resin laminated structure of Claim 1 or 6 characterized by the said resin layer containing a fluorine.   The substrate resin laminated structure according to claim 1, wherein the surface modification film and the oxide film are composed of the same element.   A surface modified film by surface modification is formed on the surface of the substrate, and at least one oxide film having a lower density than the surface modified film formed by deposition on the surface modified film is formed, An optical waveguide module, wherein an optical waveguide formed of a resin is bonded on an oxide film.

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