JP4373885B2 - Method for producing polymer optical waveguide - Google Patents

Description

  The present invention relates to the manufacture of polymer optical waveguides for propagating optical signals such as optical diffraction paths, optical branching and optical multiplexing paths, optical branching paths and optical combining paths, optical switches, optical circuits, etc. in optical information communication. It is about the method.

  Conventionally, a polymer optical waveguide includes a core and a clad covering the peripheral surface so as to surround the core. The core is formed from a transparent synthetic resin, and the cladding is formed from a transparent synthetic resin having a lower refractive index than the synthetic resin forming the core. The optical signal incident on the polymer optical waveguide is propagated through the core while being repeatedly reflected at the interface between the core and the clad. In addition to propagating the optical signal only within the core, the optical signal is emitted to the outside of the polymer optical waveguide, or the optical signal is incident from the outside to the inside of the polymer optical waveguide. 1 to Patent Document 3, a polymer optical waveguide having a mirror surface is also provided. The mirror surface is formed with a slanted boundary surface between the core and the clad so as to form a predetermined angle (for example, 45 °) with respect to the optical path constituted by the core of the polymer optical waveguide, that is, the extending direction of the core. It is provided by doing. The optical signal propagated in the core is reflected in a different direction from the conventional mirror surface, thereby changing the optical path.

  In Patent Documents 1 to 3, various polymer optical waveguide manufacturing methods have been proposed in order to form the mirror surface. For example, in Patent Document 1, a polymer optical waveguide is manufactured by dicing using a V-shaped diamond blade. That is, in the manufacturing method of Patent Document 1, a structure composed of a core and a clad is first formed, then the structure is cut by dicing, and the structure is cut so that the cut surface becomes a mirror surface. This is a polymer optical waveguide. In Patent Document 2, after forming a core and a clad, a mirror surface is formed by etching an end face by a reactive ion etching (RIE) method.

In Patent Document 3, a core, a clad, and a mirror surface are formed by using a molding die (stamper). That is, in the manufacturing method of Patent Document 3, first, after forming a molding die provided with a recess or a projection corresponding to the core, the shape of the recess or the projection is molded from the molding die, so that the core and the cladding are formed. Is molded. Further, the concave portion or the convex portion is provided with an oblique surface corresponding to the mirror surface by laser processing, and the mirror surface is also formed when the core and the clad are formed.
JP 2003-114365 A JP 2003-215371 A JP 2003-240996 A

  However, the manufacturing methods of Patent Document 1 and Patent Document 2 described above require processing for forming the mirror surface after manufacturing the core and the cladding, and it is difficult to say that the manufacturing efficiency is suitable. . On the other hand, the manufacturing method of Patent Document 3 uses a molding die, so that the manufacturing efficiency is suitable for molding of the core, the clad, and the mirror surface. However, in the manufacturing method of Patent Document 3, the apparatus related to laser processing is large and very expensive, and the manufacturing cost is likely to increase. Also in the dicing process according to Patent Document 1, the manufacturing cost is likely to increase due to the same reason as the manufacturing method of Patent Document 3. In addition, the manufacturing methods of Patent Documents 1 to 3 have positional limitations on the formation of mirror surfaces, and mirror surfaces having different inclination directions on one optical path (for example, 45 ° and −45 ° with respect to the optical path). ) Is difficult to form, and there is a limit to the tilt direction of the mirror surface that can be formed in one step, and there is a problem that the degree of freedom in designing the mirror surface is poor. If each mirror surface is processed one by one in a plurality of steps, it is possible to form mirror surfaces with different inclination directions on one optical path, but this also reduces the manufacturing efficiency. Will be invited.

  The present invention has been made paying attention to such problems existing in the prior art. The object is to provide a method of manufacturing a polymer optical waveguide that can easily manufacture a mirror surface at a suitable manufacturing efficiency and can improve the degree of freedom in designing the mirror surface. There is to do.

  In order to achieve the above-mentioned object, the invention of the method for producing a polymer optical waveguide according to claim 1 includes a clad base portion made of a synthetic resin having a core pattern recessed on the surface, and formed inside the core pattern. And a synthetic resin clad lid provided on the surface of the clad base to cover the core, and converting the optical path by forming a part of the inner surface of the core pattern into a slope shape. A manufacturing method of a polymer optical waveguide provided with a mirror surface for manufacturing a stamper provided with a transfer pattern having a shape corresponding to the core pattern, and heat embossing using the stamper A transfer step of forming the core pattern by a method, and a waveguide forming step of providing the core and the clad lid, wherein the stamper manufacturing step includes a photoresist made of a photoresist material. A coating step of coating the layer with a masking member; and a pattern formation step of exposing and developing a photoresist layer to form the transfer pattern, wherein the masking member is used during the exposure of the pattern formation step. A light source having a gradation region that gradually changes the light shielding rate in a predetermined direction is used, and the direction in which the light shielding rate is gradually changed by the gradation region is formed by the transfer pattern and the core pattern. In the pattern forming stage, a slope portion is formed in the transfer pattern using the gradation region of the masking member so as to have a shape corresponding to the mirror surface. To do.

  According to the above invention, the transfer process uses a heat embossing method using a stamper, and the stamper is formed with a transfer pattern and a slope portion. For this reason, the core pattern and the mirror surface are simply and quickly formed simply by pressing the heated stamper on the surface of the clad base and transferring the transfer pattern and the slope to the surface of the clad base. On the other hand, at the time of manufacturing the stamper, a photoresist material and a masking member provided with a gradation region are used. When exposure is performed using this masking member, the amount of light is adjusted in the gradation region, so that the photoresist layer made of the photoresist material is developed so that the portion corresponding to the gradation region becomes a slope portion. The For this reason, even if it does not require a large apparatus and a long time, a slope part can be formed by the very simple and simple operation | work which irradiates light. In addition, since the slope portion that forms the mirror surface can be formed at any position of the photoresist layer, there is no positional limitation on the formation of the mirror surface. Furthermore, if the setting of the direction in which the light shielding rate is gradually changed is changed for each slope portion, it is possible to provide a plurality of mirror surfaces having different inclination directions on one optical path. Note that changing the setting of the direction in which the light shielding rate is gradually changed can be handled by a very simple and simple operation of changing the direction in which the gradation is changed for each gradation region. Therefore, the mirror surface formation position, the tilt direction, etc. are not easily restricted, and the degree of freedom in design related to the mirror surface formation can be improved, and both the stamper having the inclined surface portion and the core pattern having the mirror surface are provided. Since it can be easily manufactured, a polymer optical waveguide having a mirror surface can be easily manufactured with suitable manufacturing efficiency.

  The invention of the method for producing a polymer optical waveguide according to claim 2 is characterized in that, in the invention according to claim 1, the photoresist material used in the coating step is a negative photoresist material. .

  According to the above invention, the negative photoresist material can increase the thickness of the photoresist layer while suppressing an increase in the manufacturing cost of the photoresist material as compared with the positive photoresist material. For this reason, even when the thickness of the photoresist layer is increased in order to increase the core diameter of the polymer optical waveguide, it is possible to maintain suitable manufacturing efficiency. In the case of increasing the thickness of the photoresist layer with a positive photoresist material, in order to suppress the occurrence of problems such as underexposure of the photoresist material, overexposure, etc. It is preferable to use an X-ray solubilization type that uses X-rays to solubilize a portion irradiated with X-rays. However, in order to expose an X-ray solubilized photoresist material, it is necessary to use an apparatus related to X-ray irradiation. Such an apparatus is large and very expensive, and the production cost is low. It is easy to invite a surge. On the other hand, when a negative photoresist material is used to increase the thickness of the photoresist layer, it is possible to use an ultraviolet curable material that uses ultraviolet light for the exposure as the photoresist material. An apparatus related to irradiation with ultraviolet rays has a simpler configuration than an apparatus related to irradiation with X-rays, and can suppress an increase in manufacturing cost.

  According to a third aspect of the present invention, there is provided a method for producing a polymer optical waveguide according to the first or second aspect of the present invention, wherein the light used for the exposure in the pattern forming stage has an absorbance of 1 for the photoresist layer. The summary is as follows.

  According to the above invention, it is possible to suitably suppress the occurrence of problems such as underexposure and overexposure of the photoresist material during exposure. For this reason, it is easy to increase the thickness of the photoresist layer, and the core diameter of the polymer optical waveguide can be increased.

  The invention of the method for producing a polymer optical waveguide according to claim 4 is the invention according to any one of claims 1 to 3, wherein the stamper producing step is performed by copying the transfer pattern. The gist includes a mold making step for obtaining a pattern and a duplication step for duplicating the transfer pattern using the duplication pattern.

  According to the above invention, the transfer pattern serving as the original plate can be stored without being used for the heat embossing, and the transfer pattern can be replicated in large quantities from the replication pattern.

  According to the present invention, a polymer optical waveguide having a mirror surface can be produced simply and with suitable production efficiency.

Hereinafter, an embodiment embodying the present invention will be described in detail with reference to the drawings.
First, the configuration of the polymer optical waveguide will be described. Polymer optical waveguides, such as optical fiber connectors and splitters, are used as optical diffraction paths, optical branching and optical multiplexing paths, optical branching paths and optical combining paths, optical switches, optical circuits, etc. It is what is used.

  As shown in FIGS. 1A and 1B, the polymer optical waveguide includes a cladding base portion 11, a core pattern 12 including a plurality of concave portions provided on the surface of the cladding base portion 11, and the core pattern 12. It has a core 13 provided inside and a clad lid 14. The clad base 11 is formed in a rectangular shape from a film, a plate material or the like. The core pattern 12 is recessed on the surface of the clad base 11 by a hot embossing method using a stamper. The core 13 is formed in a shape corresponding to the core pattern 12 so as to fill the inside of the core pattern 12. The clad lid part 14 is formed in a thin plate shape, and is attached to the surface of the clad base part 11 so as to cover the exposed part of the core 13.

  The clad base 11, the core 13, and the clad lid 14 are all made of a transparent synthetic resin so as to transmit light used as an optical signal. Synthetic resins used for the clad base 11 and the clad lid 14 include thermoplastic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyarylate (PAr), polystyrene (PS), and ultraviolet curable epoxy resins. UV curable resins such as UV curable acrylic resins and UV curable vinyl resins, and fluorine resins. In the clad base part 11, it is preferable to use a thermoplastic resin from the viewpoint of easily forming the core pattern 12 by a hot embossing method. On the other hand, the core 13 is made of a synthetic resin having a higher refractive index than the synthetic resin used in the clad base 11 and the clad lid 14. Specific examples of the synthetic resin used for the core 13 include thermoplastic resins, ultraviolet curable resins, fluororesins, and the like previously mentioned as materials for the clad base 11 and the clad lid 14, and thermosetting resins such as polyimide. Can be mentioned.

  Here, regarding the synthetic resin used for the clad base 11, the clad lid 14 and the core 13, transparent means transparent in the wavelength range of light used as an optical signal propagated by the polymer optical waveguide, that is, an optical signal. Indicates that the color tone does not absorb the light used. Therefore, not only a colorless and transparent synthetic resin, but a colored transparent synthetic resin may be used as long as it does not absorb light used for an optical signal. Specifically, light having a wavelength range of 400 to 1600 nm is used for the optical signal, and light having a wavelength range of 650 nm, 850 nm, 1300 nm, and 1550 nm is selected and used depending on the application. For this reason, as a material used for the clad base 11, the clad lid 14 and the core 13, a transparent synthetic resin having a color tone which does not absorb light in these wavelength ranges is used.

  When an optical signal is incident on the core 13 from the end of the polymer optical waveguide, the optical signal is reflected at the boundary surface between the cladding base 11 or the cladding lid 14 and the core 13. By repeating this reflection, the optical signal travels in the core 13 while drawing a sawtooth locus, and propagates in the direction in which the core 13 extends in the polymer optical waveguide. Here, the optical path of the present embodiment indicates the propagation direction of the optical signal by the polymer optical waveguide. As described above, the optical path of the optical signal propagated in the core 13 (the direction of the arrow in the horizontal direction in the figure) coincides with the extending direction of the core 13 in the present embodiment.

  In the polymer optical waveguide, mirror surfaces 15 are provided at the boundary surfaces between the clad base 11 and the core 13 at both ends (both ends of the optical path) in the extending direction of the core 13. Each mirror surface 15 has an inclined surface with a predetermined angle (45 ° in this embodiment) with respect to the optical path. These mirror surfaces 15 are formed by forming a pair of opposing inner side surfaces, which are a part of the inner surface of the core pattern 12, into tapered shapes that are separated from each other toward the cladding lid portion 14. The mirror surface 15 is formed by using the stamper together with the core pattern 12 when the core pattern 12 is formed by the hot embossing method.

  The traveling direction of the optical signal propagating in the polymer optical waveguide is changed by changing the reflection direction at the mirror surface 15. That is, an optical signal incident from the outside of the polymer optical waveguide in the downward arrow direction in the figure is converted into an optical signal propagated through the core 13 by one mirror surface 15. The optical signal propagated in the core 13 is converted by the other mirror surface 15 into an optical signal emitted in the upward arrow direction in the drawing to the outside of the polymer optical waveguide. Therefore, the polymer optical waveguide provided with the mirror surface 15 is not limited to propagating an optical signal only in the core 13, but can receive an optical signal from the outside via the cladding lid 14. It is also possible to emit an optical signal to the outside via 14.

  In the core pattern 12, the roughness of the inner surface including the mirror surface 15 is preferably 1/10 or less, more preferably 1/20 or less of the wavelength range of light used for the optical signal. Specifically, the arithmetic average roughness (Ra) defined in JIS B0601-1994 is preferably 0.2 μm or less, more preferably 0.1 μm or less. When Ra exceeds 0.2 μm, irregular reflection of light is likely to occur at the boundary surface when traveling in the core 13, and there is a possibility that the optical signal cannot be accurately propagated due to noise or the like. Note that as the arithmetic average roughness (Ra) becomes smaller, irregular reflection of light is less likely to occur, and an optical signal can be accurately propagated. However, if the arithmetic average roughness (Ra) is excessively reduced, the manufacturing time is increased, the complexity is increased, and the manufacturing cost is increased. Therefore, the arithmetic average roughness (Ra) is preferably 0.01 μm. That's it.

  The diameter of the core 13 is preferably 3 to 2000 μm. In addition, the diameter of the core 13 of this embodiment is shown by the length of one side of the core 13 in the plane orthogonal to the optical path. That is, when an optical signal is input from an optical fiber to a polymer optical waveguide or an optical signal is output from the polymer optical waveguide to an optical fiber, the core diameter of the polymer optical waveguide is reduced to reduce the coupling loss. Need to optimize for diameter. The polymer optical waveguide is premised on connecting an optical fiber, and the core diameter of the optical fiber is generally 3 to 2000 μm. Therefore, the diameter of the core 13 is preferably 3 to 2000 μm, and more preferably 50 to 2000 μm so that various optical fibers can be matched to the diameter of each core.

  Next, a stamper for forming the polymer optical waveguide will be described. As shown in FIGS. 3A, 3B, and 4A, the stamper includes a master stamper 21 that is an original, and a replication stamper 41 that is replicated from the master stamper 21 using a replication mold 31. It is composed of

  First, the master stamper 21 will be described. The master stamper 21 has a mask substrate 22 as a masking member and a transfer pattern 23 provided on the surface of the mask substrate 22. The transfer pattern 23 is formed using a photoresist material so as to have a shape corresponding to the core pattern 12, in other words, a shape obtained by reversing the core pattern 12. Further, the transfer pattern 23 is formed with an inclined surface portion 24 so as to have a shape corresponding to the mirror surface 15. Therefore, the transfer pattern 23 and the inclined surface portion 24 and the core pattern 12 and the mirror surface 15 are in a so-called negative / positive relationship.

  Since the surface roughness of the transfer pattern 23 and the slope portion 24 may be transferred to the inner surface of the core pattern 12 and the mirror surface 15, the surface roughness is the wavelength range of light used for the optical signal. Is preferably 1/10 or less, more preferably 1/20 or less. Specifically, the arithmetic average roughness (Ra) of the surface is preferably 0.2 μm or less, more preferably 0.1 μm or less. When Ra exceeds 0.2 μm, Ra on the inner surface of the core pattern 12 or the mirror surface 15 may exceed 0.2 μm. In addition, as the arithmetic average roughness (Ra) of the surface of the transfer pattern 23 and the inclined surface portion 24 becomes smaller, the inner surface of the core pattern 12 and the mirror surface 15 become smoother. As a result, the manufacturing cost increases. For this reason, the arithmetic average roughness (Ra) of the surface of the transfer pattern 23 and the inclined surface portion 24 is preferably 0.01 μm or more.

  The mask substrate 22 includes a base plate 25 and a masking pattern 26 provided on the surface of the base plate 25. The base plate 25 is a transparent plate material, such as a glass plate or a synthetic resin plate, which does not absorb the light used for the exposure so that the light used for the exposure of the photoresist material can be transmitted to form the transfer pattern 23. Etc. are formed. The masking pattern 26 includes a light shielding pattern 27 that shields light used for exposure, a light transmitting pattern 28 that transmits light used for exposure, and a gradation pattern provided between the light shielding pattern 27 and the light transmitting pattern 28. 29.

  The gradation pattern 29 constitutes a gradation region in which the light shielding rate for light used for exposure is gradually changed in a predetermined direction. Further, in this gradation region, the direction in which the light shielding rate with respect to the light used for exposure is gradually changed is the direction from the light shielding pattern 27 toward the light transmitting pattern 28, that is, the direction in which the core 13 extends. Are set to be in the same direction as the optical path of the optical signal propagated in the core 13.

  Specifically, the light shielding pattern 27 of the present embodiment is formed by forming a thin film on the surface of the base plate 25. The color tone of the thin film is a color tone that absorbs or reflects light used for exposure. The thin film absorbs or reflects light used for exposure, whereby light used for exposure is blocked. The translucent pattern 28 is formed by exposing the surface of the base plate 25 to the outside without providing the thin film, and transmits light used for exposure. On the other hand, the gradation pattern 29 is formed by gradually changing the film thickness of the thin film. The color tone of the thin film with the film thickness gradually changed is a color tone that absorbs or reflects light used for exposure, and the tone of the tone pattern 29 changes continuously. As it approaches 27, it becomes darker, and as it approaches the translucent pattern 28, it becomes lighter. The light shielding rate of the gradation pattern 29 corresponds to the light shielding rates of the light shielding pattern 27 and the light transmitting pattern 28. For example, if the light blocking rate of the light blocking pattern 27 is 100% and the light blocking rate of the light transmitting pattern 28 is 0%, the light blocking rate of the gradation pattern 29 is 100 to 0 in the direction from the light blocking pattern 27 toward the light transmitting pattern 28. % Continuously.

  Next, the replication mold 31 will be described. The replication mold 31 is manufactured by molding the surface portion of the master stamper 21, that is, the transfer pattern 23. The replication mold 31 is made of silicone rubber. A replication pattern 32 is provided on the surface of the replication mold 31 (upper surface in FIG. 4A). The duplicate pattern 32 has a shape corresponding to the transfer pattern 23, in other words, a shape obtained by reversing the transfer pattern 23, and the duplicate pattern 32 and the transfer pattern 23 have a so-called negative / positive relationship. Accordingly, the duplicate pattern 32 has the same shape as the core pattern 12.

  Next, the replication stamper 41 will be described. The replication stamper 41 includes a base material 42 and a transfer portion 43 provided on the surface (the bottom surface in FIG. 4A) of the base material 42. The transfer pattern 23 and the slope portion 24 are copied on the surface of the transfer portion 43 (the bottom surface in FIG. 4A). The transfer portion 43 is formed of an ultraviolet curable resin such as an ultraviolet curable epoxy resin, an ultraviolet curable acrylic resin, or an ultraviolet curable vinyl resin. In addition, the base material 42 is made of a material that does not absorb ultraviolet rays, such as a glass plate, which is used to cure the transfer portion 43.

  In this embodiment, the heating embossing method is performed using the replication stamper 41 among the stampers. This is because the transfer portion 43 made of an ultraviolet curable resin is easier to improve the strength against heating and pressurization than the transfer pattern 23 made of a photoresist material, and can be used as a stamper when performing the heat embossing method. This is because it is possible to increase the amount. Therefore, if the purpose is not to increase the number of usable times such as manufacturing only a small amount of polymer optical waveguide, the master stamper 21 may be used to perform the heat embossing method. In addition, since the ultraviolet curable resin which forms the transfer part 43 is used by the heating embossing method, it is necessary to use a resin having a glass transition point (Tg) higher than that of the synthetic resin which is the material of the cladding base 11. More preferably, a cationic polymerization type ultraviolet curable epoxy resin is used.

Next, the manufacturing process of the polymer optical waveguide will be described.
The polymer optical waveguide is manufactured through a stamper manufacturing process, a transfer process, and a waveguide forming process. In the stamper manufacturing process, the master stamper 21 and the duplicate stamper 41 are manufactured as stampers. In the transfer step, the core pattern 12 is formed on the surface of the clad base 11 by performing a heat embossing process using the replication stamper 41. In the waveguide forming step, the core 13 is formed inside the core pattern 12 on the surface of the cladding base 11 on which the core pattern 12 is formed, and then the cladding lid 14 is formed.

  The stamper manufacturing process will be described. This stamper manufacturing process is roughly divided into two stages: a master manufacturing stage for manufacturing the master stamper 21 and a replica manufacturing stage for manufacturing the replica stamper 41.

  First, the master manufacturing stage will be described. The master manufacturing stage includes a covering stage and a pattern forming stage. As shown in FIG. 2A, a photoresist layer 23a is laminated on the surface of the mask substrate 22 in the covering step. FIG. 2A shows the case where a negative photoresist material is used. The formation of the photoresist layer 23a is performed by casting (injecting) a liquid photoresist material onto the surface of the mask substrate 22, and then heating and drying the photoresist material to remove the solvent component and solidify. The photoresist layer 23a formed in this way is covered with a mask substrate 22 that is a masking member on the surface (the bottom surface in FIG. 2A). In this mask substrate 22, since the photoresist material is a negative type, the transparent pattern 28 of the masking pattern 26 has the same shape as the desired transfer pattern 23.

  In the pattern forming step, as shown by an arrow in FIG. 2A, first, light used for exposure is irradiated to the photoresist layer 23a through the mask substrate 22 from the bottom side in FIG. The photoresist layer 23a is exposed. At this time, in the gradation pattern 29 of the mask substrate 22, light used for exposure is easily transmitted from the light shielding pattern 27 side toward the light transmission pattern 28 side. The light intensity changes continuously. Thus, by continuously changing the light intensity in the gradation pattern 29, the exposure degree of the photoresist material by the light used for exposure also changes continuously between the light shielding pattern 27 and the light transmitting pattern 28. It will be. As a result, the portion corresponding to the gradation pattern 29 in the photoresist layer 23a is exposed in a sloped manner as indicated by the dotted line in FIG. Thereafter, the photoresist layer 23a is developed, and a part of the photoresist layer 23a is removed. Then, as shown in FIG. 3 (a), the transfer pattern 23 remains on the surface of the mask substrate 22, and the exposed portion of the photoresist layer 23a in the shape of a slope forms a slope portion 24, and the master stamper. 21 is formed.

  Here, a case where a positive photoresist material is used will be described. As shown in FIG. 2B, a photoresist layer 23a made of a positive photoresist material is laminated on the surface of the base plate 25, and the surface of the photoresist layer 23a is formed by a masking sheet 26a as a masking member. Covered. The masking sheet 26 a has a light shielding pattern 27, a light transmission pattern 28, and a gradation pattern 29. The light shielding pattern 27 has the same shape as the desired transfer pattern 23, and the light transmission pattern 28 is the same as the transfer pattern 23. Inverted shape. Then, as a result of exposing the photoresist layer 23a from the surface side of the masking sheet 26a, a transfer pattern having the same shape as the transfer pattern 23 shown in FIG. 3A is obtained.

  In order to increase the thickness of the photoresist layer 23a in order to increase the diameter of the core 13, it is preferable to use a negative photoresist material from the viewpoint of suppressing an increase in manufacturing cost. This is because an ultraviolet curable material can be used as long as the film thickness of the photoresist layer 23a is increased as long as it is a negative photoresist material. When a positive photoresist material is used to increase the thickness of the photoresist layer 23a, the need to use an X-ray solubilizing type increases, and a large and expensive apparatus is used for exposing the photoresist layer 23a in the pattern formation stage. The possibility of using is increased.

  A case where the thickness of the photoresist layer 23a is increased in order to increase the diameter of the core 13 (specifically, the case where the thickness of the photoresist layer 23a is 100 μm or more) will be described. In this case, in order to make the film thickness of the photoresist layer 23a uniform within the surface of the mask substrate 22, it is preferable to employ the following method in the covering step. That is, first, a spacer having the same height as the desired thickness of the photoresist layer 23 a is prepared, and the spacer is placed on the surface of the mask substrate 22. Next, a photoresist material is cast on the surface of the mask substrate 22 so as to rise above the spacer, and the photoresist material is solidified. Thereafter, using a pressing member having a flat surface, the surface of the photoresist material is pressed by the pressing member while heating the photoresist material. Then, since the surface of the photoresist material is changed from a state where the surface is raised more than the spacer to a flat state, the film thickness of the photoresist layer 23a becomes uniform.

  Further, when a pressing member is used in the covering step, a material that can deform the photoresist layer 23a at the pressing temperature is used as the photoresist material. At the time of pressing, the pressing member, the photoresist layer 23a, and the mask substrate 22 are heated so as to have a temperature equal to or higher than the glass transition point (Tg) of the unexposed photoresist material. The thickness of the photoresist layer 23a is the same as the diameter of the core 13 and is 3 to 2000 μm.

  When the photoresist layer 23a is formed to have a thickness of, for example, 100 to 2000 μm, the transfer pattern 23 is accurately formed because the exposure condition is different between the surface portion and the bottom portion (the surface of the mask substrate 22). The possibility of disappearing is increased. Therefore, the light used for exposure is preferably light having an absorbance of 1 or less with respect to the photoresist layer 23a, and more preferably light having 0.02-1. The light having an absorbance of 1 or less means a self-recording spectrophotometer (UV-manufactured by Shimadzu Corporation) in a state in which the photoresist layer 23a is formed in a desired thickness (the same length as the desired diameter of the core 13). 3100PC), the absorbance of the photoresist layer 23a is measured, and the light whose absorbance is 1 or less is shown. When light having a wavelength region with an absorbance exceeding 1 is used as light used for exposure, most of the light is absorbed by the surface portion of the photoresist layer 23a, and the light may not reach the bottom of the photoresist layer 23a. Get higher. In this case, the difference in light intensity between the surface portion and the bottom portion of the photoresist layer 23a becomes large, and optimum exposure conditions differ between the surface portion and the bottom portion.

  For example, if light in the wavelength range that is the optimum exposure condition for the bottom is used as light used for exposure, the surface portion is overexposed, so the transfer pattern has a different width between the surface portion and the bottom portion. End up. As a specific example, when light having a wavelength range exceeding 1 is used and a transfer pattern is formed with a negative photoresist layer 23a, the surface portion of the transfer pattern is wider than the bottom portion. On the other hand, if light having a wavelength range that is an optimal exposure condition for the surface portion is used as light used for exposure, the bottom portion is underexposed, and the transfer pattern has a different width between the surface portion and the bottom portion as in the previous example. It becomes a thing. Furthermore, when a negative type photoresist material is used, there is a risk that a transfer pattern may be peeled off from the substrate during development.

  The light source used for the exposure may be a light source that emits light only in a specific wavelength region, or a light source that emits light of multiple wavelengths, such as a high-pressure mercury lamp or a xenon lamp. However, when a light source that emits light only in a specific wavelength range is used, it is preferable to avoid light that emits only light in a wavelength range where the absorbance is less than 0.02. When the photoresist layer 23a is exposed only to light having a wavelength region with an absorbance of less than 0.02, the amount of light absorbed by the photoresist layer 23a decreases, and the transfer pattern 23 may not be formed. On the other hand, when using a light source that emits light of multiple wavelengths, light in a wavelength range where the absorbance is less than 0.02 may be included, but in a wavelength range where the absorbance exceeds 1. It is preferable to use a filter or the like together so that the light can be shielded.

  Next, the replica manufacturing stage will be described. This replica manufacturing stage includes a mold making stage and a replica stage. In the mold making stage, the master stamper 21 obtained in the master manufacturing stage is used to mold the transfer pattern 23 from the master stamper 21. As shown in FIG. 3B, the mold is formed by applying a liquid silicone rubber to the surface of the master stamper 21 and curing the silicone rubber to form a replication mold 31. A replica pattern 32 obtained by stamping the transfer pattern 23 is formed on the replica mold 31 obtained in the mold making stage. Further, the duplicate pattern 32 has a duplicate slope portion 33 obtained by shaping the slope portion 24. After the mold making stage, the replication mold 31 is peeled off from the surface of the master stamper 21 and used in the replication stage. Silicone rubber includes a condensation reaction type and an addition reaction type, and any of these may be used, but it is more preferable to use an addition reaction type silicone rubber. This is because the addition reaction type does not generate a by-product at the time of curing, and the volume shrinkage rate at the time of curing is small, so that the transfer pattern 23 can be molded with more precise dimensional accuracy. is there.

  Further, when the replication mold 31 is released from the master stamper 21, the transfer pattern 23 is prevented from being damaged or damaged, and the release property is improved. You may perform a mold release improvement process, such as apply | coating a type | mold agent previously. Alternatively, when the pressing member is removed from the photoresist layer 23a, or when the replication stamper 41 is released from the replication mold 31, a mold release improving process may be performed. Furthermore, when the clad base 11 is released from the master stamper 21 or the replica stamper 41, a release improvement process may be performed. Examples of such mold release improving treatment include wet treatment for applying a release agent such as fluorine resin, fluorine compound, silicone resin, and silicone compound, CVD treatment using a fluorine-containing gas, sputtering of an inorganic compound, Examples include dry processing such as vacuum deposition.

  In the replication stage, a replication stamper 41 is formed using the replication mold 31 obtained in the mold making stage. That is, as shown in FIG. 4A, first, an ultraviolet curable resin is applied to the surface of the replication mold 31, and the base material 42 is placed so as to be in contact with the ultraviolet curable resin. Thereafter, as indicated by arrows in the drawing, ultraviolet rays are irradiated from above through the base material 42. Then, the ultraviolet curable resin is cured and the transfer portion 43 is formed. Then, the transfer portion 43 is peeled from the replication mold 31 to obtain a replication stamper 41 having a transfer pattern 23 and a slope portion 24 similar to the master stamper 21 copied on the surface thereof.

  Next, the transfer process will be described. The transfer process is performed by a heat embossing method. That is, first, the replication stamper 41 and the clad base 11 are heated to a temperature equal to or higher than the glass transition point (Tg) of the synthetic resin forming the clad base 11. Next, as shown in FIG. 5A, after the heated replication stamper 41 is pressed against the surface of the cladding base 11, it is cooled until the replication stamper 41 and the cladding base 11 become below the glass transition point (Tg). The replica stamper 41 is peeled off from the clad base 11. Then, as shown in FIG. 5B, the transfer pattern 23 of the replication stamper 41 is transferred to the surface of the clad base 11 to form the core pattern 12 and the inclined surface 24 is transferred to the mirror surface 15. Is formed.

  Finally, the waveguide forming process will be described. In the waveguide forming step, first, the core 13 is formed inside the core pattern 12. The core 13 is formed by irradiating ultraviolet rays after filling the core pattern 12 with the aforementioned ultraviolet curable resin. In addition, the core pattern 12 is filled with a synthetic resin that is in a liquid state by being dissolved in a solvent, and the solvent is volatilized under a reduced-pressure atmosphere or at a temperature atmosphere equal to or lower than Tg of the synthetic resin that is the material of the cladding base 11. The core 13 may be formed by curing the synthetic resin. Thereafter, as shown in FIGS. 1A and 1B, a clad lid 14 is formed on the surface of the clad base 11, and a polymer optical waveguide is manufactured. The clad lid 14 is formed by attaching a film, applying an ultraviolet curable resin to the surface of the clad base 11 and curing it by irradiating with an ultraviolet ray, applying a liquid synthetic resin by spin coating or the like, and curing. It is performed by the method of making it.

The effects exhibited by the above embodiment will be described below.
The polymer optical waveguide of the embodiment has a mirror surface 15 for converting the optical path. The mirror surface 15 is formed by transferring the inclined surface portion 24 of the replication stamper 41 to the surface of the cladding base 11 by a heating embossing method using the replication stamper 41. Further, the duplication stamper 41 is obtained by copying the transfer pattern 23 and the slope portion 24 from the master stamper 21. The transfer pattern 23 and the sloped portion 24 of the master stamper 21 are formed using a mask substrate 22 having a photoresist material and a gradation pattern 29. For this reason, the formation of the transfer pattern 23 and the inclined surface portion 24 is performed by exposure and development of the photoresist layer 23a, and is performed in a short time and easily without complicated methods such as etching and laser processing. It is possible.

  In addition, a negative photoresist material is used for forming the transfer pattern 23 of the master stamper 21. The negative photoresist material can increase the thickness of the photoresist layer while suppressing an increase in the manufacturing cost of the photoresist material as compared with the positive photoresist material. For this reason, even when the thickness of the photoresist layer is increased in order to increase the core diameter of the polymer optical waveguide, it is possible to maintain suitable manufacturing efficiency.

  In addition, the light used for the exposure of the photoresist layer 23a having a film thickness of 100 μm or more has a wavelength region in which the absorbance of the photoresist layer 23a is 1 or less. Thereby, it is possible to suppress a difference in optimum exposure conditions between the surface portion and the bottom portion of the photoresist layer 23a, and it is possible to make the transfer pattern 23 formed from the photoresist layer 23a into a suitable shape. It is.

  Further, by duplicating the duplication stamper 41 from the master stamper 21 and using the duplication stamper 41 for the heat embossing, the master stamper 21 as the original plate can be maintained for a long period of time, and the production efficiency is improved. be able to.

In addition, this embodiment can also be changed and embodied as follows.
As shown in FIG. 6A, a photoresist layer 23a is formed from a negative photoresist material, and the photoresist layer 23a is exposed using a mask substrate 22 composed of a base plate 25 and a masking pattern 26. May be. Further, as shown in FIG. 6B, a photoresist layer 23a is formed from a positive photoresist material, and has a light shielding pattern 27, a light transmission pattern 28, and a gradation pattern 29 similar to the masking pattern 26. The photoresist layer 23 a may be exposed using the sheet 26 a and the base plate 25. In these cases, the master stamper 21 is not a convex shape as shown in FIG. 3A, but is formed as a concave shape, and the slope portion 24 is formed in FIGS. 6A and 6B. As it goes upward, the taper is spaced apart from each other.

  In FIGS. 2B and 6B, the photoresist layer 23a is formed from a negative photoresist material, and in FIGS. 2A and 6A, the photoresist layer 23a is a positive photoresist. You may form from a material. However, in this case, it becomes difficult to produce the clad base 11. In the case of using a negative type photoresist material, in order to make the clad base 11 suitable and the like, from the results shown in FIG. 2A and FIG. It is preferable to provide the photoresist layer 23a on the surface of the mask substrate 22 so that the masking pattern 26 is sandwiched between the resist layer 23a. On the other hand, in the case of using a positive type photoresist material, in order to make the clad base 11 suitable and the like, from the results shown in FIG. 2B and FIG. The surface is preferably covered with a masking sheet 26a.

  As shown in FIG. 7B, in the polymer optical waveguide, the core pattern 12 is formed so that the pair of mirror surfaces 15 are arranged in a triangular shape in the middle part (in the middle of the optical path) in the direction in which the core 13 extends. May be. This polymer optical waveguide is of a junction type that connects the optical path inside the core 13 and the external optical path. The master stamper 21 has a shape as shown in FIG. That is, in the mask substrate 22, two masking patterns 26 are provided on the surface of the base plate 25. These masking patterns 26 have a translucent pattern 28 and a gradation pattern 29, and the gradation patterns 29 are arranged adjacent to each other.

  As shown in FIG. 8B, in the polymer optical waveguide, a mirror surface 15 is provided at an intermediate portion (in the middle of the optical path) in the direction in which the core 13 extends, and the height of the mirror surface 15 is made larger than the diameter of the core 13. Alternatively, the optical path of a part of the optical signal propagated through the core 13 may be converted by partially opening the optical path inside the core 13. In this case, the master stamper 21 has a shape as shown in FIG. That is, in the mask substrate 22, two masking patterns 26 are provided on the surface of the base plate 25. These masking patterns 26 have a translucent pattern 28 and a gradation pattern 29, and the gradation patterns 29 are arranged adjacent to each other. Further, the gradation pattern 29 has a lower light shielding rate than that of the embodiment.

  In the present embodiment, the mirror surfaces 15 are tapered at both ends (both ends of the optical path) in the direction in which the core 13 extends. However, the mirror surface 15 is not limited to the shape of the embodiment and can be shaped as desired. It may be provided as appropriate. For example, the master stamper 21 shown in FIG. 9 is obtained by combining the transfer pattern 23 having the slope portion 24 shown in FIGS. 3A, 7A, and 8A. Further, the master stamper 21 is inclined not only in the slope portion 24 inclined in the thickness direction (vertical direction in the drawing) of the mask substrate 22 but also in the surface direction (front and rear or horizontal direction in the drawing) of the mask substrate 22. It also has two slope portions 24a. Even the transfer pattern 23 having both the inclined surface portion 24 and the second inclined surface portion 24a can be easily created by appropriately combining the light shielding pattern, the translucent pattern, and the gradation pattern of the masking pattern 26. Is possible. A polymer optical waveguide as shown in FIG. 10 is obtained by a heating embossing method using the master stamper 21 or a replica stamper obtained from the master stamper 21. In this polymer optical waveguide, a detector and a light source (laser device (LD) or light emitting diode (LED)) (not shown) are provided on the upper surface of the clad lid 14. In this polymer optical waveguide, an optical signal propagated in the core 13 is emitted to the detector by each mirror surface 15, or an optical signal incident from the light source is cored by each mirror surface 15. 13 is configured to be propagated through the inside. In addition, an optical signal can be emitted and incident between the cores 13 inside the polymer optical waveguide by the second mirror surface 15a formed by the second inclined surface portion 24a. In addition, the polymer optical waveguide shown in FIG. 10 can individually determine the position and inclination direction of the mirror surface 15 or the second mirror surface 15a for each optical path, and the end of the optical path in each optical path. Or the optical signal can be taken out from any part of each optical path. On the other hand, when the detector is provided on the lower surface of the clad base 11, the master stamper 21 as shown in FIG. 11A is used and the mirror surfaces 15 facing each other as shown in FIG. 11B are provided. Thus, an optical signal can be emitted or incident to the outside of the polymer optical waveguide through the cladding base 11. As described above, according to the polymer optical waveguide manufacturing method of the present invention, in forming the mirror surface, there is no restriction on the formation position and restriction on the inclination direction, and any inclination direction at any desired position on the optical path. It is possible to provide a mirror surface. In addition, as shown in FIG. 9, by appropriately setting the masking pattern, it is possible to form transfer patterns having various slope portions in one process, and from the transfer pattern, various mirrors can be formed. It is also possible to form the surface in one step. Therefore, according to the present invention, it is possible to improve the design freedom related to the formation of the mirror surface while suitably maintaining the manufacturing efficiency related to the formation of the mirror surface.

  The mirror surface 15 is not limited to 45 °, and may be any angle as long as it is an angle exceeding 0 ° and less than 90 °, such as 30 °, 60 °, or the like. When the angle of the mirror surface 15 is θ, the length of the gradation pattern 29 is L, and the thickness of the photoresist layer 23a is T, L = T ÷ between the angle θ, the length L, and the thickness T. The relational expression of tan θ is established.

The mirror surface 15 may be used as a mirror surface by forming a reflective layer made of a metal film, a dielectric multilayer film, or the like on the mirror surface 15.
The gradation pattern 29 is not limited to the formation of a thin film, for example, it is painted with an intermediate color such as gray whose density changes continuously, is formed with polished glass, or is formed by printing a dot pattern. May be.

  The replica stamper 41 is not limited to the one shown in the embodiment. For example, as shown in FIG. 4B, a metal element such as nickel (Ni) is applied to the surface of the replica mold 31 by a method such as electroforming. You may manufacture by the method of depositing. Thus, when the replication stamper 41 is made of metal, strength and durability can be improved as compared with a resin stamper.

  The duplication stamper 41 may be composed of only the transfer unit 43. Alternatively, the base material 42 is not limited to the glass substrate, and the same material as the base plate 25 may be used. For example, when a silicon substrate or the like is used as the base material 42, a thermosetting resin is used as the material of the transfer portion 43, and the master stamper 21 is heated to cure the thermosetting resin. May be.

  The replication mold 31 is not necessarily formed of silicone rubber, and is formed of, for example, the above-described ultraviolet curable resin, thermoplastic resin, fluororesin, thermosetting resin, or other synthetic resin, thermoplastic elastomer, or the like. Also good. In addition, the replication mold 31 may be manufactured from a synthetic resin film, substrate, or the like by a heating embossing method using the master stamper 21.

  The clad lid portion 14 may be made of any synthetic resin as long as it has a lower refractive index than the synthetic resin used in the core 13 and has a refractive index similar to that of the clad base portion 11. For example, the cladding base 11 may be formed of a thermoplastic synthetic resin and the cladding lid 14 may be formed of an ultraviolet curable resin. Or you may form the clad cover part 14 with thermosetting resins, such as a polyimide. The clad lid 14 may be formed by applying a liquid thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, or the like on the surface of the clad base 11 by a method such as a spin coating method and curing it.

  The clad base 11 is not necessarily formed by the heating embossing method, and is formed by, for example, applying a thermosetting resin or an ultraviolet curable resin to the surface of the master stamper 21 or the replica stamper 41 and curing it. May be.

  The polymer optical waveguide may be provided on the surface of a substrate material such as a silicon substrate, a metal substrate, a metal oxide substrate, or a glass substrate. When the polymer optical waveguide is provided on the surface of the substrate material as described above, the cladding base 11 is laminated on the surface of the substrate material (not shown).

Further, the technical idea that can be grasped from the embodiment will be described below.
A method of manufacturing a stamper used for forming a core pattern provided with a mirror surface for converting an optical path on a polymer optical waveguide by a heat embossing method, wherein a photoresist layer made of a photoresist material is masked And a pattern forming step of forming a transfer pattern having a shape corresponding to the core pattern by exposure and development of the photoresist layer. In the covering step, the pattern formation is performed as the masking member. Using a gradation region that gradually changes the light shielding rate with respect to light used at the stage of exposure in a predetermined direction, and the direction in which the light shielding rate is gradually changed by the gradation region includes the transfer pattern and The core pattern that is to be formed by the core pattern is set in the extending direction, and the pattern is In the turn forming stage, a slope portion is formed in the transfer pattern using the gradation region of the masking member so as to have a shape corresponding to the mirror surface.

  The masking member includes a base plate and a masking pattern, and in the covering step, the photoresist layer is formed on the surface of the masking member so as to sandwich the masking pattern between the base plate and the photoresist layer. The method for producing a polymer optical waveguide according to any one of claims 2 to 4, wherein:

(A) is sectional drawing which shows the state which looked at the polymer optical waveguide of embodiment from the front, (b) is sectional drawing which shows the state which looked at the polymer optical waveguide of embodiment from the side. (A) And (b) is a sectional side view which shows the state which exposes a photoresist material. (A) is a sectional side view showing a master stamper, (b) is a sectional side view showing a state in which a replica mold is manufactured. (A) And (b) is a sectional side view which shows the state which manufactures a replication stamper. (A) is a side sectional view showing a state in which a clad base is molded using a replica stamper, and (b) is a side cross sectional view showing a molded clad base. (A) And (b) is a sectional side view which shows the state which exposes a photoresist material by another method. (A) is a sectional side view showing a master stamper of another form, (b) is a sectional side view showing a polymer optical waveguide of another form. (A) is a sectional side view showing a master stamper of another form, (b) is a sectional side view showing a polymer optical waveguide of another form. The perspective view which shows the master stamper of another form. The perspective view which shows the polymer optical waveguide of another form. (A) is a sectional side view showing a master stamper of another form, (b) is a sectional side view showing a polymer optical waveguide of another form.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Cladding base part, 12 ... Core pattern, 13 ... Core, 14 ... Cladding lid part, 21 ... Master stamper, 22 ... Substrate, 23 ... Transfer pattern, 23a ... Photoresist layer, 31 ... Duplicate type, 32 ... Duplicate pattern, 41: replication stamper, 51: spacer, 52: pressing member, 53: mask member, 54: opening pattern, 55: light shielding pattern.

Claims (4)

A synthetic resin clad base with a core pattern recessed on the surface, a core formed inside the core pattern, and a synthetic resin clad lid provided on the surface of the clad base to cover the core A polymer optical waveguide provided with a mirror surface for converting the optical path by forming a part of the inner surface of the core pattern into a slope shape,
A stamper manufacturing process for manufacturing a stamper provided with a transfer pattern having a shape corresponding to the core pattern, a transfer process for forming the core pattern by a heat embossing method using the stamper, and the core and cladding lid A waveguide forming step of providing
The stamper manufacturing process includes a coating step of coating a photoresist layer made of a photoresist material with a masking member, and a pattern formation step of exposing and developing the photoresist layer to form the transfer pattern,
In the covering step, the masking member is provided with a gradation region that gradually changes the light shielding rate with respect to light used in the exposure in the pattern forming step in a predetermined direction, and the light shielding rate is gradually increased by the gradation region. The direction to be changed is set so that the core formed by the transfer pattern and the core pattern extends.
In the pattern forming step, a slope portion is formed in the transfer pattern by using the gradation region of the masking member so as to have a shape corresponding to the mirror surface. 2. The method of manufacturing a polymer optical waveguide according to claim 1, wherein the photoresist material used in the coating step is a negative photoresist material. 3. The method of manufacturing a polymer optical waveguide according to claim 1, wherein the light used at the time of exposure in the pattern forming step has an absorbance with respect to the photoresist layer of 1 or less. 4. 2. The stamper manufacturing process includes: a mold making step for obtaining a duplicate pattern by taking the transfer pattern; and a duplication step for duplicating the transfer pattern using the duplicate pattern. The method for producing a polymer optical waveguide according to claim 3.

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