JP7511395B2 - Photoelectric conversion element and its manufacturing method - Google Patents

Description

The present invention relates to a photoelectric conversion element for converting electrical signals received by an antenna into optical signals by modulating the intensity of a light source using a conversion circuit, and vice versa, converting optical signals into radio wave electrical signals that can be transmitted by an antenna, in a next-generation communication network using optical fibers. The present invention also relates to a method for manufacturing a photoelectric conversion element in which a core layer that serves as an optical waveguide and electrodes for antenna transmission and reception are patterned by simultaneous double-sided exposure, and to a photoelectric conversion element in which the cladding layer is primarily composed of a cyclic olefin resin with excellent dielectric properties.

A conventional optical waveguide invention is disclosed in Patent Document 1. In the invention of Patent Document 1, after an optical waveguide is formed on a dummy substrate, the optical waveguide is peeled off from the dummy substrate (singulation process) and bonded to a semiconductor chip via an adhesive. However, this method requires a singulation process for the optical waveguide, which is cumbersome. Furthermore, in these singulation and bonding processes, it is difficult to achieve high-precision alignment. Such alignment problems arise not only between the semiconductor chip and the optical waveguide, but also between the optical waveguide and the antenna transmission/reception electrode pattern.

JP 2006-39390 A

In a method in which the individual optical waveguide and antenna electrode substrate are separately prepared and then bonded together, the relative positions of the two are different from one another, and the difference in positional misalignment causes differences in the efficiency of optical-electrical signal conversion, making it impossible to obtain a photoelectric conversion element of stable quality. Furthermore, if the dielectric properties of the adhesive that bonds the antenna electrode substrate and optical waveguide are insufficient, problems such as transmission loss of electrical signals propagating near the adhesive interface occur, causing delays in information transmission, etc. In particular, with millimeter wave radio waves, a high proportion of electrical signals propagate near the interface due to the skin effect, and transmission loss becomes very large, which poses the problem of being unable to meet the needs of next-generation communication networks that require high speed, large capacity, and low latency. In order to solve these problems, the inventors have made the following invention.

In other words, the first characteristic feature of the present invention is a method for manufacturing a photoelectric conversion element in which a core layer is provided on the surface of a cladding layer, an electrode layer and a resist layer are provided on the back surface of the cladding layer, and then both sides of the core layer and the resist layer are exposed simultaneously to light, thereby providing a patterned core layer and a patterned electrode layer.

The second characteristic feature of the present invention is a photoelectric conversion element that includes a patterned core layer provided on the surface of a clad layer and a patterned electrode layer provided on the back surface of the clad layer, the clad layer being mainly composed of a cyclic olefin resin. The third characteristic feature of the present invention is a photoelectric conversion element in which the arithmetic mean roughness Ra of the back surface of the clad layer is 0.01 to 0.3 μm.

・・・式（１） A fourth characteristic feature of the present invention is a photoelectric conversion element in which the cyclic olefin resin has a crystallinity of 1% to 30%. A fifth characteristic feature of the present invention is a photoelectric conversion element in which the cyclic olefin resin has a structure of C _n H _2n+1 (n = 0 to 8) in which the substituents R ₁ and R ₂ in formula (1) are not connected to each other.

...Equation (1)

The sixth characteristic feature of the invention is a photoelectric conversion element in which the core layer is made of at least one material selected from the group consisting of deuterated silicon, deuterated acrylic, ultraviolet curable epoxy, ultraviolet curable acrylate, benzocyclobutene, and fluorinated polyimide.

According to the first characteristic configuration of the present invention, the method for manufacturing a photoelectric conversion element of the present invention provides a core layer on the surface of a cladding layer, provides an electrode layer and a resist layer on the back surface of the cladding layer, and then exposes the core layer and the resist layer simultaneously on both sides to provide a patterned core layer and a patterned electrode layer. This has the effect of enabling the manufacture of a photoelectric conversion element with extremely high positional accuracy between the patterned core layer and the patterned electrode layer. In addition, as a result of the extremely stable positional relationship between the patterned core layer and the patterned electrode layer, the conversion between the optical signal transmitted through the patterned core layer and the electrical signal transmitted through the patterned electrode layer is extremely efficient and stable. In addition, the number of exposure and development steps is approximately half that of the single-sided case, which can greatly contribute to improving productivity.

Furthermore, according to a second characteristic configuration of the present invention, the photoelectric conversion element of the present invention comprises a patterned core layer provided on the surface of a clad layer, and a patterned electrode layer provided on the back surface of the clad layer, and the clad layer is mainly composed of a cyclic olefin resin. Cyclic olefin resins have low moisture absorption and water absorption, and have excellent dielectric properties (especially dielectric properties in the millimeter wave band region), so that the transmission loss of electrical signals propagating near the clad layer interface in the patterned electrode layer is extremely small. As a result, there is an effect that it can be applied to photoelectric conversion elements for next-generation communication networks that require high speed, large capacity, and low latency.

Furthermore, according to the third characteristic configuration of the present invention, the photoelectric conversion element of the present invention has an arithmetic mean roughness Ra of the rear surface of the clad layer of 0.01 to 0.3 μm. Therefore, since a dense and moderate fine irregularity is formed on the rear surface of the clad layer, the anchor effect of the fine irregularity has the effect of increasing the adhesive strength between the clad layer and the electrode layer. In addition, since the irregularity is much denser and finer than that of general-purpose plating pretreatment, there is also the effect that it is less susceptible to the effects of a decrease in electrical resistance, even for electrical signals of millimeter wave band radio waves, which have a high proportion of electrical signals propagating near the interface.

Furthermore, according to the fourth characteristic configuration of the present invention, in the photoelectric conversion element of the present invention, the crystallinity of the cyclic olefin resin is 1% to 30%. Therefore, since the polymer main chain is formed in an oriented manner compared to general amorphous cyclic olefin resins, by surface-modifying the surface of that portion with a functional group having high affinity with the electrode layer, it is possible to efficiently improve the adhesive strength between the clad layer and the electrode layer. In addition, since the dielectric properties tend to be improved compared to amorphous cyclic olefin resins, it is also possible to further reduce the transmission loss of electrical signals propagating near the clad layer interface in the patterned electrode layer.

・・・式（１） According to a fifth characteristic configuration of the present invention, in the photoelectric conversion element of the present invention, the cyclic olefin resin is formed of a structure in which the substituents R ₁ and R ₂ in formula (1) are not connected and have a structure of C _n H _2n+1 (n=0 to 8). Therefore, since the substituents R ₁ and R ₂ are small and not bulky, adjacent polymer main chains are easily close to each other, which has the effect of increasing the crystallinity. As a result, the adhesive strength between the cladding layer and the electrode layer can be efficiently improved, and the transmission loss of an electrical signal propagating near the cladding layer interface in the patterned electrode layer can be further reduced.

...Equation (1)

Furthermore, according to a sixth characteristic configuration of the present invention, the photoelectric conversion element of the present invention has a core layer made of at least one selected from the group consisting of deuterated silicon, deuterated acrylic, ultraviolet curable epoxy, ultraviolet curable acrylate, benzocyclobutene, and fluorinated polyimide. Therefore, since the core layer is made of a material with relatively small cure shrinkage, it has the effect of being able to form an optical waveguide for propagating optical signals with good dimensional accuracy. Furthermore, if the cure shrinkage of the core layer is small, the warping of the cladding layer due to curing is also small and it is kept flat, so the core layer itself is also kept flat. As a result, it has the effect of being able to form an optical waveguide that is flat and allows optical signals to easily propagate.

1A to 1C are schematic cross-sectional views showing an example of a manufacturing process of a photoelectric conversion element in a first characteristic configuration of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a photoelectric conversion element according to a second characteristic configuration of the present invention. FIG. 2 is a schematic perspective view showing an example of a photoelectric conversion element according to a second characteristic configuration of the present invention.

Hereinafter, an embodiment of the photoelectric conversion element and its manufacturing method according to the present invention will be described with reference to the drawings. The photoelectric conversion element 1 of the present invention is characterized in that a patterned core layer 30 is formed on the surface of a cladding layer 10, and a patterned electrode layer 20 is formed on the back surface of the cladding layer 10 on which fine irregularities 11 are formed. It is preferable to form an upper cladding layer 40 by covering the patterned core layer 30, and a lower electrode layer 60 may be provided below the patterned electrode layer 20 via a substrate 50 (see Figures 2 and 3).

The method for manufacturing the photoelectric conversion element 1 of the present invention includes providing a core layer 35 on the surface of the cladding layer 10, providing an electrode layer 25 and a resist layer 70 on the back surface of the cladding layer 10 on which the fine irregularities 11 are formed (see FIG. 1(a)), and then arranging photomasks 80 on the top of the core layer 35 and the bottom of the resist layer 70, respectively, and emitting exposure light from the top and bottom light sources of the main optical system to simultaneously expose both sides (see FIG. 1(b)). After developing the core layer 35 and the resist layer 70, etching a part of the exposed electrode layer 25, and peeling off and removing a part of the developed core layer 35 and the resist layer to form a patterned core layer 30 and a patterned electrode layer 20 on the front and back surfaces of the cladding layer 10 (see FIG. 1(c)).

By simultaneously exposing the core layer 35 and the resist layer 70 on both sides, the patterned core layer 30 and the patterned electrode layer 20 are formed with good positional accuracy, efficiently, and with good productivity, making it possible to mass-produce high-performance, high-quality photoelectric conversion elements 1. Furthermore, in the case of simultaneous double-sided exposure, the number of exposure and development steps is approximately half that of single-sided exposure, which contributes greatly to improving productivity. When performing this simultaneous double-sided exposure, it is recommended to use a simultaneous double-sided projection exposure machine in which a projection lens and a photomask 80 are placed on each side of the workpiece.

The alignment for double-sided simultaneous exposure may be performed between the upper and lower photomasks 80 and between the photomask 80 and the workpiece. The alignment between the upper and lower photomasks 80 may be performed by placing a position detection system between the photomasks 80 on the upper photomask 80, simultaneously projecting the alignment marks of the upper and lower photomasks 80 on a position detection microscope, and moving the upper photomask 80 based on the measurement results. The alignment between the photomask 80 and the workpiece may be performed by placing a workpiece alignment detection system on the workpiece, measuring the alignment mark position of the lower photomask 80 while irradiating it with exposure light from the lower main optical system before the workpiece is loaded, and then moving the position of the workpiece to align the upper and lower photomasks 80 with the workpiece.

Examples of the exposure light emitted from the light source of the main optical system include ultraviolet light, far ultraviolet light, and extreme ultraviolet light. The material of the resist layer 70 can be selected according to the exposure light emitted. For example, if 436 nm ultraviolet light is used as the exposure light, a novolac resin can be selected for the resist layer 70, and if 248 nm far ultraviolet light is used as the exposure light, a polyhydroxystyrene resin-based chemically amplified photoresist can be selected for the resist layer 70. The thickness of the resist 70 is preferably 5 to 100 μm.

The developer may be an alkaline aqueous solution or an organic solvent-based developer, but any developer may be used as long as it can develop the core layer 35 and the resist layer 70. However, organic solvent-based developers are flammable and harmful to the human body, so a water-based mixed liquid such as a diethylene glycol monoalkyl ether derivative and water is preferable. The developer may contain a hydrophilic nucleophile such as ethanolamine. When developing, the developer should be heated to a temperature of 40°C to 60°C to ensure smooth development.

When the resist layer 70 is developed, a part of the electrode layer 25 is exposed, and the electrode layer in the exposed area is peeled off and removed by a method such as etching to form a patterned electrode layer 20. Etching can be performed by immersing in an etching solution such as an aqueous solution of ferric chloride or nital (a mixture of ethanol and nitric acid). Then, when the resist layer 70 is peeled off after etching, a patterned electrode layer 20 and a patterned core layer 30 are formed on the front and back surfaces of the cladding layer 10 (see FIG. 1(c)).

The cladding layer 10 is preferably formed from a material whose main component is a cyclic olefin resin. Cyclic olefin resin is a resin with very low hygroscopicity, low water absorption, and high water vapor barrier properties, and has excellent dielectric properties (very low dielectric constant, low dielectric tangent). Therefore, it is possible to reduce attenuation of electrical signals propagating within the patterned electrode layer 20 near the interface with the cladding layer 10, and to reduce transmission loss.

Cyclic olefin resins widely used in optical applications are amorphous, but for the present invention, it is preferable to use a cyclic olefin resin with a crystallinity of 1 to 30% rather than an amorphous cyclic olefin resin. This is because the polymer main chain is oriented in the crystalline portion, and by modifying the surface of that portion with a functional group that has a high affinity with the electrode layer, the adhesive strength between the clad layer and the electrode layer can be efficiently improved. In addition, the dielectric properties tend to be further improved compared to amorphous cyclic olefin resins, so the transmission loss of electrical signals propagating near the clad layer interface in the patterned electrode layer can be further reduced. Note that cyclic olefin resins with a crystallinity of more than 30% are brittle and difficult to process, and are difficult to manufacture in the first place.

The crystallinity of the cyclic olefin resin of the cladding layer 10 may be measured by X-ray diffraction. Specifically, fitting is performed between the crystalline portion that forms the peak shape portion and the amorphous portion that forms the baseline portion, and the crystallinity is calculated by substituting each integrated intensity into the following formula. In the formula, X represents the crystalline scattering integrated intensity (i.e., the scattering integrated intensity derived from the crystalline portion), and Y represents the amorphous scattering integrated intensity (i.e., the scattering integrated intensity derived from the amorphous portion).
Crystallinity (%) = [X / (X + Y)] x 100

Examples of the cyclic olefin resin having a crystallinity of 1% to 30% include cyclic olefin resins in which the substituents R ₁ and R ₂ of formula (1) are not connected and have a structure of C _n H _2n+1 (n = 0 to 8). In the case of a cyclic polyolefin polymer having a ring structure in which the substituents R ₁ and R ₂ of formula (1) are connected, the distance between the main chains of the polymer is increased due to the bulky substituent, and the orientation of the main chain of the polymer is inhibited, resulting in an amorphous polymer with a crystalline portion of less than 1%. Since the higher the crystallinity, the more effectively the adhesion strength can be improved, it is preferable that the substituents R ₁ and R ₂ are substituents with a low value of n in C _n H _2n+1 . If the value of n is a large substituent exceeding 8, there is a tendency for there to be no significant difference from the case of a substituent in which R ₁ and R ₂ are connected.

An example of a cyclic olefin resin with a crystallinity of 1% to 30% is a hydrogenated cyclic olefin ring-opening polymer having a repeating unit derived from a polycyclic norbornene monomer. The hydrogenated cyclic olefin ring-opening polymer is obtained by using a metal compound as a polymerization catalyst to solution polymerize a norbornene monomer to obtain a ring-opening polymer, thereby obtaining a cyclic olefin ring-opening polymer having syndiotactic stereoregularity, and then hydrogenating the main chain carbon-carbon double bond of the ring-opening polymer. The norbornene monomer is preferably a norbornene compound having a norbornene skeleton and a ring structure condensed to the norbornene skeleton in the molecule. In this case, it may be copolymerized with a norbornene compound not having a ring structure condensed to the norbornene skeleton, a monocyclic olefin, a cyclic diene, and derivatives thereof.

By carrying out some kind of surface modification treatment on the cyclic olefin resin surface of the cladding layer 10, the adhesion strength between the cladding layer 10 and the electrode 20 can be improved. For example, cyclic olefin resin is mostly composed of non-polar C-H bonds, but one example of surface modification is to cut some of these C-H bonds and change them to functional groups such as -OH groups, -COOH groups, and -CO groups that have affinity with metal materials. In particular, since the C-H bonds in crystalline areas are oriented in an almost regular and dense manner, modifying these areas to the above-mentioned functional groups can effectively improve the adhesion strength.

Then, if fine irregularities 11 are formed on the back surface of this cladding layer 10 and an electrode 20 is formed directly on that back surface (see Figure 2), metal particles of the electrode 20 are deposited so as to penetrate into the deep recesses of the fine irregularities 11, and the resulting anchor effect can further improve the adhesion strength between the cladding layer 10 and the electrode 20. The shape of the fine irregularities 11 that can maintain this anchor effect while adequately securing a path for electrical signals propagating near the interface has an arithmetic mean roughness Ra of 0.01 to 0.3 μm. If Ra is less than 0.01 μm, sufficient adhesion strength cannot be obtained, and if Ra is greater than 0.3 μm, it is difficult to secure a propagation path for electrical signals compatible with millimeter wave band waves.

The method for forming the fine irregularities 11 is preferably a surface modification method using ultraviolet irradiation or plasma treatment under specific conditions. This is because the surface can be modified to change to functional groups such as -OH groups, -COOH groups, and -CO groups at the same time as forming the fine irregularities 11. Thermal imprinting is one method, but it is not very suitable for endless mass production over a large area, and the surface is not modified to the functional groups. Corona discharge treatment, which is widely used, is also one method, but the set conditions for stably forming the fine irregularities 11 in the above range are narrow.

The conditions for surface modification by ultraviolet irradiation are, for example, using an ultraviolet lamp and irradiating for about 3 to 10 minutes from a distance of 1 to 3 cm from the cladding layer 10. If the distance is greater than the above or the irradiation time is shorter, the desired fine irregularities 11 cannot be obtained. Conversely, if the distance is closer than the above or the irradiation time is longer, the irregularities become too large or the unevenness becomes too uneven. The conditions for surface modification by plasma treatment are, for example, using a xenon excimer lamp that emits vacuum ultraviolet light in an oxygen or carbon tetrafluoride atmosphere and irradiating for about 2 to 5 minutes from a distance of 0.5 to 2 cm from the cladding layer 10. If the distance is greater than the above or the irradiation time is shorter, the desired fine irregularities 11 cannot be obtained, and conversely, if the distance is closer than the above or the irradiation time is longer, the irregularities become too large or the unevenness becomes too uneven.

The thickness of the cladding layer 10 is preferably as thin as possible within the range of 10 μm to 500 μm. Specifically, 10 μm to 150 μm is preferable. The thinner the cladding layer 10, the closer the distance between the patterned electrode layer 20 and the patterned core layer 30, making it easier to convert electrical signals to optical signals, and improving performance as a photoelectric conversion element. However, if the thickness is less than 10 μm, it is difficult to maintain mechanical strength during the process of simultaneously exposing both sides, and if the thickness exceeds 500 μm, it is likely to cause problems in the conversion of electrical signals to optical signals.

The electrode layer 25 is a layer mainly composed of a metal film, and examples of materials include pure conductive metals such as copper, gold, silver, aluminum, nickel, palladium, and indium, as well as conductive paste films containing the above metals, conductive fibers containing the above metals, and oxide films containing the above metals. Methods for forming the electrode 25 include electrolytic or electroless plating, as well as methods such as sputtering, vacuum deposition, and diffusion transfer.

The pattern of the patterned electrode 20 may be an antenna receiving or transmitting electrode pattern that receives radio signals transmitted from the outside and transmits radio signals to the outside. Specifically, it may be a U-shape that approximates a square with a side length of 0.5 mm to 2 mm as shown in FIG. 3. The thickness of the patterned electrode 20 may be 0.03 to 20 μm. If the thickness of the patterned electrode 20 is less than 0.03 μm, the patterned electrode 20 is divided by the fine irregularities 11, making it difficult to ensure a propagation path for electrical signals, and if the thickness of the electrode 20 exceeds 20 μm, the adhesion strength with the clad layer 10 is likely to decrease even if the fine irregularities 11 are appropriately formed and the surface is appropriately modified.

In order to shield radio signal noise, a substrate 50 and a lower electrode layer 60 may be provided under the patterned electrode layer 20 (see Figures 2 and 3). There are no particular limitations on the material and thickness of the substrate 50 as long as it has a certain degree of dielectric properties, and it may be the same material and thickness as the cladding layer 10, or it may be different. There are no particular limitations on the material and thickness of the lower electrode layer 60, and it may be the same material and thickness as the electrode layer 25, or it may be different. When bonding the patterned electrode layer 20 and the substrate 50, for example, a low-dielectric polyimide adhesive may be applied. This is because the use of a low-dielectric polyimide adhesive can prevent attenuation of the electrical signal in the patterned electrode layer 20 that propagates near the interface.

The core layer 35 is a layer that is exposed to exposure light, developed, and patterned, and examples of materials include resins such as deuterated silicon, deuterated acrylic, UV-curable epoxy, UV-curable acrylate, benzocyclobutene, and fluorinated polyimide. These materials have relatively small shrinkage on cure, so the optical waveguide that propagates optical signals, i.e., the patterned core layer 30, can be formed with good dimensional accuracy. Furthermore, if the core layer 35 has small shrinkage on cure, the warping of the cladding layer 10 that accompanies cure is also small, and the core layer 35 itself is kept flat. As a result, a flat optical waveguide that easily propagates optical signals can be formed.

The shape of the patterned core layer 30 is not particularly limited as long as it can propagate an optical signal, but examples include elongated tubular shapes with a rectangular or circular cross section. In order for light to propagate as a signal within the patterned core layer 30, it is necessary to confine the light within the patterned core layer 30, and for this purpose, it is preferable to provide an upper clad layer 40 on the surface of the clad layer 10 so as to cover the patterned core layer 30 (see Figures 2 and 3). The material of the upper clad layer 40 is not particularly limited, but in order to confine the light within the waveguide, it is preferable to select a material of the same quality as the clad layer 10 or a material with a small difference in refractive index from the clad layer 10. The upper clad layer 40 is preferably formed using a coater capable of coating and applying a thick film.

The difference in refractive index between the patterned core layer 30 and the cladding layer 10 and upper cladding layer 40 causes light to be confined within the optical waveguide, so when light is input from one direction, the light travels along the optical waveguide until it is output, and a wireless electrical signal converted according to the input optical signal is transmitted as a radio wave from the patterned electrode 20. It is also possible to convert the radio wave wireless electrical signal received by the patterned electrode 20 into an optical signal.

In this way, a patterned core layer 30 is formed on the surface of the cladding layer 10, and the patterned core layer 30 is covered with an upper cladding layer 40 to form an optical waveguide, and a patterned electrode layer 20 for the desired antenna reception or transmission is formed on the back surface of the cladding layer 10 consisting of fine irregularities 11, and is formed at a predetermined position with good positional accuracy with the patterned core layer 30, resulting in a photoelectric conversion element 1 with less attenuation of the received or transmitted electrical signal, smooth conversion of optical signals to electrical signals, and improved antenna reception or transmission performance. As a result, the device can be deployed in products for various applications such as millimeter wave optical modulators, millimeter wave photoelectric cells, collision prevention millimeter wave radars using optical fibers, antenna converters, marine radars, wireless LANs, FWAs, and ETCs.

・・・式（１） As a clad layer, a cyclic olefin resin polymer film having a thickness of 50 μm and a crystallinity of 15%, in which the substituents R ₁ and R ₂ of formula (1) are hydrogen atoms, was prepared. The back surface of the film was irradiated with an ultraviolet lamp having a wavelength of 254 nm for 10 minutes from a distance of 2 cm from the back surface of the clad layer to form fine irregularities with an arithmetic average roughness of 0.2 μm. The film was then immersed in an electroless copper plating bath (copper sulfate pentahydrate 0.03 mol/L, formalin 0.3 mol/L, Rochelle salt complexing agent 0.3 mol/L, pH 12.5) at 25° C., and then in an electrolytic copper plating bath (copper sulfate pentahydrate 10%, sulfuric acid 18%, hydrochloric acid 0.5%, organic additives 1%, ion-exchanged water 70.5%) at 25° C. to form an electrode layer made of a copper film having a thickness of 2 μm on the back surface of the clad layer.

...Equation (1)

Next, a resist layer made of a polyhydroxystyrene resin-based chemically amplified photoresist was formed on the surface of the electrode layer with a thickness of 20 μm using a reverse coater, and a core layer made of an ultraviolet-curable epoxy resin was formed on the surface of the cladding layer with a thickness of 30 μm using a reverse coater. Next, a double-sided simultaneous projection exposure machine was prepared, and a photomask for the optical waveguide pattern was placed on the top of the core layer. After placing a photomask for the antenna receiving electrode pattern on the bottom of the resist layer, 248 nm far ultraviolet light was emitted from the upper and lower light sources of the main optical system to simultaneously expose both sides of the core layer and the resist layer.

Then, it was immersed in a mixed developer of water and a diethylene glycol monoalkyl ether derivative containing ethanolamine at 50°C, and then immersed in an etching solution of an aqueous solution of ferric chloride. After the above immersion, it was washed with pure water, and a core layer patterned to the pattern of the optical waveguide was formed on the surface of the cladding layer, and an electrode layer consisting of an antenna receiving electrode pattern was formed on the back surface of the cladding layer. Next, an upper cladding layer made of the same cyclic olefin resin as the cladding layer was formed to a thickness of 50 μm using a reverse coater so as to cover the upper part of the patterned core layer, and a substrate on which a lower electrode layer with electromagnetic wave shielding function was formed was attached to the lower part of the patterned electrode layer via a low dielectric polyimide adhesive, and the desired photoelectric conversion element was obtained.

The obtained photoelectric conversion element has an optical waveguide in the patterned core layer and an antenna electrode pattern in the patterned electrode layer formed at the desired position with high positional precision, efficiency and productivity, and the electrical signal received by the antenna electrode pattern has little attenuation and smoothly converts optical signals to electrical signals. This has resulted in a high-performance, high-quality device that can be deployed in products for a variety of applications, such as millimeter-wave optical modulators, millimeter-wave photocells, collision prevention millimeter-wave radars using optical fibers, antenna converters, marine radars, wireless LANs, FWAs, and ETCs.

As the cladding layer, a 100 μm thick cyclic olefin resin polymer film with a crystallinity of 3% was prepared, which was made of a hydrogenated cyclic olefin ring-opening polymer having a repeating unit derived from a polycyclic norbornene monomer. A 30 μm thick resist layer made of a novolac resin and a 30 μm thick core layer made of an ultraviolet-curable acrylic resin were formed, and the same procedure as in Example 1 was carried out to obtain the desired photoelectric conversion element, except that a double-sided simultaneous projection exposure machine with 436 nm ultraviolet exposure light was used. The photoelectric conversion element of this example was also a photoelectric conversion element with the same positional accuracy as Example 1, efficient productivity, and smooth conversion of optical signals to electrical signals with little attenuation of the electrical signals.

REFERENCE SIGNS LIST 1 Photoelectric conversion element 10 Cladding layer 11 Fine irregularities on the rear surface of the cladding layer 20 Patterned electrode layer 25 Electrode layer 30 Patterned core layer 35 Core layer 40 Upper cladding layer 50 Substrate 60 Lower electrode layer 70 Resist layer 80 Photomask

Claims (4)

preparing a clad layer mainly composed of a cyclic olefin resin having a crystallinity of 1% to 30%;
forming a core layer on one surface of the clad layer;
forming an electrode layer on the other surface of the cladding layer;
forming a resist layer on the electrode layer;
a step of forming a core layer which becomes a patterned optical waveguide and an electrode layer which becomes a patterned antenna by simultaneously exposing both sides of the core layer and the resist layer;
A method for manufacturing an optical waveguide and an antenna comprising the steps of: 2. The method for manufacturing an optical waveguide and an antenna according to claim 1, further comprising the step of subjecting the surface of the other side of the cladding layer to ultraviolet irradiation or plasma treatment so that the arithmetic mean roughness Ra of the surface is 0.01 to 0.3 μm. The cyclic olefin resin is a group represented by the following formula (1): ₁ and R ₂ And it doesn't connect, and C _n H _2n+1 The method for producing an optical waveguide and an antenna according to claim 1, wherein the optical waveguide and antenna have a structure where n is 0 to 8.

...Equation (1) 2. The method for manufacturing an optical waveguide and an antenna according to claim 1, wherein the core layer is made of at least one selected from the group consisting of deuterated silicon, deuterated acrylic, ultraviolet curable epoxy, ultraviolet curable acrylate, benzocyclobutene, and fluorinated polyimide.

Images