JP3977047B2 - Optical component and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical component such as a thermo-optic effect type optical switch and a manufacturing method thereof.
[0002]
[Prior art]
The thermo-optic effect is a change in refractive index due to heat. As an optical component using the thermo-optic effect, a thermo-optic effect type optical switch is exemplified.
The thermo-optic effect type optical switch switches the optical path by utilizing the thermo-optic effect, and is an optical component capable of switching the light output port by energizing the metal thin film heater.
[0003]
FIG. 3 is a plan view showing a conventional thermo-optic effect type optical switch.
The thermo-optic effect type optical switch includes a core 1 that is an optical waveguide, a cladding layer 2 having a refractive index lower than that of the core 1, optical path switching heaters 3a and 3b, incident ports 7a and 7b, and an emission port. Ports 8a and 8b.
The core 1 serves as an optical waveguide, and is a quadrangle whose one side is 5 to 10 μm. Furthermore, in this thermo-optic effect type optical switch, a Y-type branch core is formed in which one core 1a is branched into two, a core 1b and a core 1c, as shown in FIG. This Y-shaped branch core is composed of a straight portion 9a, a branch portion 9b, and a separation portion 9c.
[0004]
Examples of the material for forming the core 1 include optical communication plastic and quartz glass. Among them, for example, a polyimide resin such as a fluorinated polyimide resin is preferable because it has a large thermo-optical effect.
The clad layer 2 is formed on a silicon substrate (not shown) so as to surround the core 1. In addition, examples of the material for forming the cladding layer 2 include the same materials as those for forming the core 1.
[0005]
The optical path switching heater 3 is a linear heater made of a thin film such as gold, titanium, aluminum, chromium, or nichrome. These optical path switching heaters 3a and 3b are provided along the cores 1b and 1c of the separating portion 9c from the core 1a of the straight portion 9a of the Y-type branch core where the traveling direction of light is switched or branched. Yes. The optical path switching heaters 3 a and 3 b are provided on the upper surface of the cladding layer 2. Furthermore, for example, rectangular electrode pads 5a and 5b are provided at both ends of the optical path switching heaters 3a and 3b, respectively, and external electrodes (not shown) are connected to them.
The control of the optical path utilizes, for example, that when the optical path switching heater 3a is heated, the refractive index of the heated core 1b decreases and the light concentrates on the other core 1c.
That is, when the optical path switching heater 3a is heated, the light is guided to the core 1c, and when the optical path switching heater 3b is heated, the light is guided to the core 1b.
[0006]
A method for manufacturing such a thermo-optic effect type optical switch will be described below.
First, a lower clad layer is formed on the upper surface of a silicon substrate (not shown) by spin coating, and a core layer corresponding to the thickness of the core 1 is formed on the entire upper surface. Next, after masking the pattern of the core 1 on the upper surface of the core layer by photolithography, the core layer is processed by reactive ion etching or the like to form the core 1. At this time, a plurality of cores 1 can be formed on a single substrate. Next, the upper clad layer is formed again on the lower clad layer and the core 1 by spin coating or the like, and the clad layer 2 in which the lower clad layer and the upper clad layer are integrated is formed.
[0007]
Next, a metal thin film made of gold, titanium, aluminum, chromium, nichrome or the like is formed on the clad layer 2 by sputtering or the like. Next, after masking the patterns of the optical path switching heaters 3a and 3b by photolithography, the metal thin film is etched or lifted off to form the optical path switching heaters 3a and 3b, and a plurality of thermo-optic effect optical switch chips. A silicon substrate on which is formed is obtained.
Next, a plurality of thermo-optic effect optical switch chips formed on the silicon substrate are cut out by a processing machine such as a dicing saw to obtain a thermo-optic effect optical switch chip.
[0008]
[Problems to be solved by the invention]
In the manufacturing method of the thermo-optic effect type optical switch, in order to form the core 1 and the clad layer 2, a polyimide resin precursor polyamic acid or the like is applied on a silicon substrate, and then the polyimide resin precursor. Is heated at 300 to 400 ° C.
By the way, the thermal expansion coefficient of polyimide resin is larger than the thermal expansion coefficient of silicon. Accordingly, when the core 1 and the clad layer 2 are formed and then returned to room temperature, stress that tends to shrink is generated in the core 1 and the clad layer 2 due to the difference in thermal expansion coefficient between the polyimide resin and silicon.
When the chip of the thermo-optic effect type optical switch is cut out in such a state, the end portions of the core 1 and the cladding layer 2 are lifted from the silicon substrate due to the residual stress at the end portion of the chip of the thermo-optic effect type optical switch. There was something to do.
[0009]
This invention is made | formed in view of the said situation, and makes it a subject to provide the optical component by which the core laminated | stacked on the board | substrate made from a silicon | silicone, and a clad do not peel, and its manufacturing method.
[0010]
[Means for Solving the Problems]
The subject is an optical component including a substrate in which a core and a clad layer formed so as to surround the core are laminated, and an optical path switching heater comprising a conductive thin film on the upper surface of the clad layer is provided. provided, the outer peripheral edge of the clad layer is edged with the conductive thin film, the light component, can be solved by a heat-optic switch der Ru optical component.
That is, the problems include a step of forming a lower clad layer on a substrate, a step of forming a core on the upper surface of the lower clad layer, an upper clad layer on the lower clad layer and the core, A step of forming a clad layer in which the lower clad layer and the upper clad layer are integrated; a step of forming a conductor thin film on the upper surface of the clad layer; an optical path switching heater and an optical component chip comprising the conductor thin film Can be solved by a method of manufacturing an optical component, which includes a step of simultaneously forming a border of the optical component and a step of cutting out the optical component chip.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
FIG. 1 is a plan view showing a thermo-optic effect type optical switch as an example of the optical component of the present invention. 2 is a cross-sectional view showing a state cut along II-II in FIG.
In this example, the thermo-optic effect type optical switch includes a core 12 that is an optical waveguide, a cladding layer 13 having a refractive index lower than that of the core 12, and optical path switching heaters 14a and 14b on the silicon substrate 11. And a conductive thin film 15 that borders the outer peripheral edge of the upper surface of the cladding layer 13.
Further, the thermo-optic effect type optical switch of this example is a 2 × 2 thermo-optic effect type optical switch provided with two incident ports 18a and 18b and two emission ports 19a and 19b.
As an example of use of this 2 × 2 thermo-optic effect type optical switch, for example, when used in an ADM (Add / Drop Module), one incident port 18a is connected to a wavelength demultiplexer, and the other The incident port 18b is for entering the added light.
One emission port 19a is connected to a wavelength multiplexer, and the other emission port 19b is for emitting dropped light.
[0012]
The substrate 1 is a flat plate made of silicon and having a thickness of about 100 to 1000 μm. The size of the substrate 1 is appropriately set according to the size of the thermo-optic effect type optical switch.
[0013]
As shown in FIG. 2, the core 12 is a square shape having a cross-sectional shape of about 5 to 10 μm. Examples of the material for forming the core 12 include plastics having a large thermo-optic effect. Examples thereof include polyimide resins such as fluorinated polyimide resins, methacrylic resins such as silicone resins and fluorinated polymethacrylates. These are materials suitable for the core 12 because their thermo-optic coefficients are an order of magnitude larger than those of glass materials such as quartz glass.
[0014]
The clad layer 13 is formed on the substrate 11 so as to surround the periphery of the core 12 and has a thickness of several tens of μm. The material for forming the cladding layer 13 may be the same as the material for forming the core 12, but a material having a refractive index lower than that of the core 12 is used.
[0015]
In particular, when a polyimide resin is used as a material for forming the core 12 and the cladding layer 13, after applying a predetermined amount of a precursor of this resin on a silicon substrate, it is heated to 300 to 400 ° C, The core 12 and the clad layer 13 are formed.
As the precursor of the polyimide resin used here, polyamic acid is used. Specific examples thereof include 2,2′-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), 4 4,4'-oxydianiline (ODA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl.
[0016]
The optical path switching heaters 14a and 14b are linear heaters made of a thin film such as gold, titanium, aluminum, chromium, or nichrome. The optical path switching heaters 14 a and 14 b are provided on the upper surface of the cladding layer 13. For example, rectangular electrode pads 16a and 16b are provided at both ends of the optical path switching heaters 14a and 14b, respectively, and external electrodes (not shown) are connected to them.
[0017]
The conductor thin film 15 is made of a thin film of gold, titanium, aluminum, chromium, nichrome or the like and has a linear border covering the outer peripheral edge of the upper surface of the cladding layer 13, similarly to the optical path switching heaters 14 a and 14 b. .
The thickness of the conductor thin film 15 is about 0.5 to 2.0 μm, preferably 0.5 to 1.0 μm. The conductor thin film 15 has a width of about 5 to 20 μm, preferably 6 to 8 μm. Moreover, the shape of the conductor thin film 15 can be arbitrarily set according to the shape of the thermo-optic effect type optical switch.
If the conductor thin film 15 is present at the outer peripheral edge of the upper surface of the cladding layer 13, elastic deformation of the core 12 and the cladding layer 13 can be suppressed by the rigidity of the conductor thin film 15. Therefore, it is possible to prevent the core 12 and the cladding layer 13 from being lifted from the substrate 11 and peeled off due to the residual stress at the end of the chip of the thermo-optic effect type optical switch.
[0018]
As another example of the optical component of the present invention, for example, a variable optical attenuator including a substrate in which a core made of plastic and a clad layer made of plastic formed so as to surround the core are laminated. And a waveguide type grating filter.
[0019]
The method for manufacturing the optical component of the present invention will be described by showing a method for manufacturing the thermo-optic effect type optical switch of this example.
First, for example, a polyamide resin precursor polyamic acid or the like is applied to the upper surface of a silicon substrate by a spin coating method, and heated to 300 to 400 ° C. to form a lower cladding layer. Next, a polyimide resin precursor polyamic acid or the like is applied to the entire upper surface of the lower cladding layer by spin coating, and heated to 300 to 400 ° C. to form a core layer corresponding to the thickness of the core 12. . Next, the core layer is processed by reactive ion etching or the like along the pattern of the core 12 formed by photolithography to form the core 12. Next, a polyimide resin precursor polyamic acid or the like is applied onto the lower clad layer and the core 12 by spin coating, and heated to 300 to 400 ° C. to form an upper clad layer. A clad layer 13 in which the upper clad layer is integrated is formed.
[0020]
Next, a conductor thin film made of a metal such as gold, titanium, aluminum, chromium, or nichrome is formed on the entire upper surface of the cladding layer 13 by sputtering or the like. Next, after masking the patterns of the optical path switching heaters 14a and 14b and the conductive thin film 15 by photolithography, the conductive thin film is etched to form the optical path switching heaters 14a and 14b and the conductive thin film 15, and a plurality of them are formed. A silicon substrate on which the chip of the thermo-optic effect type optical switch is formed is obtained. Next, a plurality of thermo-optic effect type optical switch chips formed on the silicon substrate are cut out by a processing machine such as a dicing saw to obtain a thermo-optic effect type optical switch chip.
[0021]
In the manufacturing method of the thermo-optic effect type optical switch of this example, the conductor thin film 15 bordering the outer peripheral edge of the upper surface of the optical path switching heaters 14a and 14b and the cladding layer 13 can be formed simultaneously. The number of processes does not increase. Therefore, it is possible to easily manufacture a thermo-optic effect type optical switch in which the core 12 and the clad layer 13 do not peel from the substrate 11 due to residual stress.
[0022]
Hereinafter, the effect of the present invention will be clarified by showing specific examples with reference to FIGS. 1 and 2.
Example 1
Polyamic acid was applied to the upper surface of a 1000 μm thick silicon substrate by spin coating, and heated at 360 ° C. or more for about 8 hours to form a lower cladding layer. Next, polyamic acid as a precursor of polyimide resin is applied to the entire upper surface of the lower cladding layer by spin coating, and heated at 360 ° C. or more for about 8 hours to form a core layer corresponding to the thickness of the core 12. Formed. Next, this core layer was processed by reactive ion etching along the pattern of the core 12 formed by photolithography to form a 7.0 μm square core 12. Next, polyamic acid is applied onto the lower cladding layer and the core 12 by spin coating, and heated at 360 ° C. or more for about 8 hours to form an upper cladding layer. The lower cladding layer and the upper cladding layer are integrated. A clad layer 13 having a thickness of 35 μm was formed. Next, a conductor thin film made of gold and chromium was formed on the entire upper surface of the cladding layer 13 by sputtering. Next, after masking the patterns of the optical path switching heaters 14a and 14b and the conductive thin film 15 by photolithography, the conductive thin film is etched to obtain the outer periphery of the optical path switching heaters 14a and 14b and the thermo-optic effect type optical switch chip. A conductive thin film 15 having edges was formed, and a silicon substrate on which a plurality of thermo-optic effect type optical switch chips were formed was obtained.
Next, the plurality of thermo-optic effect type optical switch chips were cut out with a dicing saw to obtain a thermo-optic effect type optical switch chip having a border consisting of a plurality of conductive thin films 15.
[0023]
(Example 2)
Except for alternately providing the portions where the conductor thin film 15 that borders the outer peripheral edge of the chip of the thermo-optic effect type optical switch is formed and the portions that are not formed on the upper surface of the cladding layer 13 formed on the silicon substrate. In the same manner as in Example 1, a chip of a thermo-optic effect type optical switch having a border made of a plurality of conductive thin films 15 and a chip of a thermo-optic effect type optical switch having no border made of a conductive thin film 15 are used. Got.
[0024]
(Comparative Example 1)
Except that the conductor thin film 15 is not formed on the upper surface of the clad layer 13 formed on the silicon substrate, it does not have a border composed of a plurality of conductor thin films 15 as in the first embodiment. A chip of a thermo-optic effect type optical switch was obtained.
[0025]
In the chip of the thermo-optic effect type optical switch obtained in Example 1, the core 12 and the cladding layer 13 are not lifted from the substrate 11 and are peeled off after being cut out from the silicon substrate with a dicing saw. It never happened.
In the chip of the thermo-optic effect type optical switch obtained in Example 2, the chip having a border made of the conductive thin film 15 after being cut out from a silicon substrate with a dicing saw has a core 12 and a cladding layer 13. Did not lift from the substrate 11 and did not peel off. On the other hand, the core 12 and the cladding layer 13 were lifted from the substrate 11 and peeled off from the chip made of the conductive thin film 15 and having no border.
In the chip of the thermo-optic effect type optical switch obtained in Comparative Example 1, the core 12 and the cladding layer 13 were lifted from the substrate 11 and separated after being cut out from the silicon substrate with a dicing saw.
[0026]
【The invention's effect】
As described above, the optical component of the present invention is an optical component including a substrate in which a core and a cladding layer formed so as to surround the core are laminated, and the outer periphery of the upper surface of the cladding layer. Since the edge is edged with the conductor thin film, the core and the clad layer can be prevented from being lifted off from the substrate due to the residual stress at the edge of the optical component.
The optical component manufacturing method of the present invention includes a step of forming a lower clad layer on a substrate, a step of forming a core on the upper surface of the lower clad layer, the lower clad layer, and an upper clad on the core. Forming a layer, forming a clad layer in which the lower clad layer and the upper clad layer are integrated, forming an edge of an optical component chip made of a conductive thin film on the upper surface of the clad layer, A step of cutting out the optical component chip, and an optical path switching heater formed on the upper surface of the cladding layer of the optical component, and a conductor thin film bordering the outer peripheral edge of the upper surface of the cladding layer of the optical component. Since they can be formed at the same time, it is possible to easily manufacture an optical component in which the core and the cladding layer do not peel from the substrate due to residual stress.
[Brief description of the drawings]
FIG. 1 is a plan view showing an example of an optical component of the present invention.
FIG. 2 is a cross-sectional view showing an optical component of the present invention, and is a cross-sectional view showing a state cut along II-II in FIG.
FIG. 3 is a plan view showing a conventional thermo-optic effect type optical switch.
FIG. 4 is a plan view showing an example of a Y-type branch core in a conventional thermo-optic effect type optical switch.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Board | substrate, 12 ... Core, 13 ... Clad layer, 14a, 14b ... Heater for optical path switching, 15 ... Conductor thin film, 16a, 16b ... Electrode pad, 18a, 18b ... Incoming ports, 19a, 19b ... Outgoing ports

Claims (2)

An optical component comprising a substrate on which a core and a clad layer formed so as to surround the core are laminated,
The optical path switching heater comprising a conductive thin film on the upper surface of the cladding layer is provided, the outer peripheral edge of the clad layer is edged with the conductive thin film, wherein the optical component is heat-optic switch der Rukoto Optical parts characterized by   Forming a lower clad layer on the substrate; forming a core on an upper surface of the lower clad layer; forming an upper clad layer on the lower clad layer and the core; the lower clad layer and the upper clad layer A step of forming a clad layer integrated with the clad layer, a step of forming a conductor thin film on the upper surface of the clad layer, and an optical path switching heater and an optical component chip made of the conductor thin film are simultaneously formed. An optical component manufacturing method comprising: a step; and a step of cutting out the optical component chip.

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