WO2022157958A1 - Optical waveguide and method for producing same - Google Patents

Optical waveguide and method for producing same Download PDF

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Publication number
WO2022157958A1
WO2022157958A1 PCT/JP2021/002385 JP2021002385W WO2022157958A1 WO 2022157958 A1 WO2022157958 A1 WO 2022157958A1 JP 2021002385 W JP2021002385 W JP 2021002385W WO 2022157958 A1 WO2022157958 A1 WO 2022157958A1
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optical waveguide
clad layer
deuterium
amorphous
plasma
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PCT/JP2021/002385
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French (fr)
Japanese (ja)
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泰 土澤
達郎 開
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日本電信電話株式会社
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Priority to PCT/JP2021/002385 priority Critical patent/WO2022157958A1/en
Priority to JP2022576949A priority patent/JPWO2022158001A1/ja
Priority to PCT/JP2021/024832 priority patent/WO2022158001A1/en
Publication of WO2022157958A1 publication Critical patent/WO2022157958A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
    • G02B6/13—Integrated optical circuits characterised by the manufacturing method
    • G02B6/132—Integrated optical circuits characterised by the manufacturing method by deposition of thin films

Definitions

  • the present invention relates to an optical waveguide using amorphous silicon and a manufacturing method thereof.
  • Recent advances in silicon photonics technology have led to the development of waveguide fabrication technology that uses high-refractive-index silicon waveguides to allow light to propagate with low loss even in extremely fine and sharp bends, and has achieved compatibility with electronic devices and materials.
  • waveguide fabrication technology that uses high-refractive-index silicon waveguides to allow light to propagate with low loss even in extremely fine and sharp bends, and has achieved compatibility with electronic devices and materials.
  • This optoelectronics convergence technology is gaining importance as a key technology for realizing high speed, miniaturization, low power consumption, and low cost of devices in the field of communication.
  • silicon waveguides are also suitable for optical coupling with light-emitting devices and light-receiving devices made of compound semiconductors with similar refractive indices.
  • Technology development for integration is also progressing.
  • the present invention was made to solve this problem, and aims to realize an optical waveguide using amorphous silicon with low optical loss, high heat resistance, and high stability, and a manufacturing method thereof.
  • a method for manufacturing an optical waveguide according to the present invention includes steps of generating plasma of an inert gas and deuterium gas, and irradiating a silicon target with the plasma to cause sputtering. depositing silicon particles generated by the sputtering on the lower clad layer to form an amorphous silicon film containing deuterium; processing the amorphous silicon film into an optical waveguide core; and forming an upper cladding layer over the core.
  • the method for manufacturing an optical waveguide includes the steps of irradiating a silicon target with plasma of an inert gas to cause sputtering, depositing silicon particles generated by the sputtering on a lower clad layer, forming a first amorphous silicon film; introducing deuterium gas into the plasma to form a second amorphous silicon film; forming the first amorphous silicon film and the second amorphous silicon film;
  • the method includes a step of processing a silicon film into an optical waveguide core, and a step of forming an upper clad layer so as to cover the optical waveguide core.
  • an optical waveguide according to the present invention includes, in order, a lower clad layer, an optical waveguide core having amorphous silicon containing deuterium, and an upper clad layer covering the optical waveguide core.
  • an optical waveguide using amorphous silicon with low optical loss and high stability and a manufacturing method thereof can be provided.
  • FIG. 1 is a schematic cross-sectional view showing the configuration of an optical waveguide according to a first embodiment of the present invention.
  • FIG. 2 is a schematic cross-sectional view showing the configuration of a film forming apparatus in the optical waveguide manufacturing method according to the first embodiment of the present invention.
  • FIG. 3 is a flowchart of a film forming method in the optical waveguide manufacturing method according to the first embodiment of the present invention.
  • FIG. 4 is a diagram for explaining the method of manufacturing the optical waveguide according to the first embodiment of the present invention.
  • FIG. 5 is a schematic cross-sectional view showing the configuration of an optical waveguide according to a second embodiment of the invention.
  • FIG. 6 is a flow chart of a film forming method in the optical waveguide manufacturing method according to the second embodiment of the present invention.
  • FIG. 1 An optical waveguide according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
  • FIG. 1 An optical waveguide according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
  • FIG. 1 An optical waveguide according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
  • FIG. 1 An optical waveguide according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
  • the optical waveguide 10 sequentially covers a silicon (Si) substrate 11, a lower clad (SiO 2 ) layer 12, an optical waveguide core 13, and an optical waveguide core 13. and a cladding layer 14 .
  • the optical waveguide core 13 is made of amorphous Si containing deuterium, and has a width of about 300 to 500 nm and a thickness of about 200 to 300 nm, for example.
  • the clad layer 14 is made of SiO 2 and has a thickness of about 2 to 3 ⁇ m, for example.
  • FIG. 2 shows a cross-sectional view of an example of an ECR sputtering apparatus used as a film forming apparatus in this embodiment.
  • An amorphous Si thin film which will be the core material of the optical waveguide, is deposited by the ECR sputtering apparatus 100 .
  • the ECR sputtering apparatus 100 includes, in order, a chamber 101, a plasma generation chamber 102, a vacuum waveguide 106, and a waveguide 108, which are in communication with each other.
  • the chamber 101 communicates with an evacuation device (not shown), and the inside thereof together with the plasma generation chamber 102 is evacuated by the evacuation device.
  • the chamber 101 is provided with a sample table 104 on which a substrate 103 on which a film is to be formed is fixed.
  • the sample stage 104 tilts and rotates at a desired angle.
  • the sample table 104 is rotatable by a rotating mechanism (not shown).
  • a ring-shaped silicon target 105 is provided so as to surround the opening region in the chamber 101 where the plasma from the plasma generation chamber 102 is introduced.
  • the silicon target 105 is placed in a container 105 a made of an insulator, and the inner surface is exposed inside the chamber 101 .
  • the plasma generation chamber 102 communicates with a vacuum waveguide 106 , and the vacuum waveguide 106 is connected to a waveguide 108 via a quartz window 107 .
  • Waveguide 108 communicates with a microwave generator (not shown). The microwave generator, the waveguide 108, the quartz window 107, and the vacuum waveguide 106 constitute microwave supply means.
  • a magnetic coil 110 is also provided around and above the plasma generation chamber 102 . Note that there is also a configuration in which a mode converter is provided in the middle of the waveguide 108 .
  • a silicon substrate 103 on which a 3 ⁇ m thick thermal oxide film is formed is placed on a sample table 104 in a chamber 101 .
  • the silicon substrate 103 corresponds to the silicon substrate 11 in the optical waveguide 10 and the thermal oxide film corresponds to the lower clad layer (SiO 2 ) 12 .
  • argon gas which is an inert gas, is introduced into the plasma generation chamber 102 from the inert gas introduction unit 111 .
  • deuterium is introduced into the chamber 101 through a gas introduction section 112 installed separately from the inert gas introduction section, and the pressure inside the plasma generation chamber 102 is set to about 10-3 Pa, for example.
  • the ECR plasma forms a plasma flow in the direction of the sample stage 104 due to the divergent magnetic field from the magnetic coil 110 .
  • the microwave power supplied from the microwave generation unit is branched at the waveguide 108, and the plasma generation is performed in the vacuum waveguide 106 above the plasma generation chamber 102. It is coupled from chamber 102 through quartz window 107 .
  • This configuration can prevent scattering particles from the silicon target 105 from adhering to the quartz window 107, and can greatly improve the running time.
  • a high-frequency voltage is applied to the ring-shaped silicon target 105 provided between the plasma generation chamber 102 and the sample table 104, thereby attracting the plasma to the surface of the silicon target 105 and irradiating it. to cause sputtering.
  • particles of the target material fly out from the surface of the silicon target 105 and reach the substrate 103 together with the plasma emitted from the plasma generation chamber 102 .
  • deuterium gas activated by plasma also reaches the substrate 103 together with the particles.
  • amorphous Si containing deuterium is deposited on the substrate 103, and an amorphous Si film is formed on the thermal oxide film of the substrate 103 (step 2_12).
  • the film thickness to be deposited can be controlled by checking the deposition rate in advance and controlling the sputtering time. For example, the sputtering is stopped when the film thickness of the amorphous Si to be deposited reaches 200 nm (step 2_13). As a result, an amorphous Si film with a thickness of 200 nm is formed on the thermal oxide film with a thickness of 3 ⁇ m.
  • an oxide film (SiO 2 ) 12 is formed on a silicon substrate 11 (step 1).
  • an amorphous Si thin film 13_1 is formed on the oxide film (SiO 2 ) 12 by the film forming method described above (step 2).
  • a mask pattern 15 of SiO 2 is formed on the amorphous Si thin film 13_1 by a normal lithographic technique (step 3).
  • a silicon oxide film is formed on an amorphous Si thin film by plasma CVD.
  • a resist mask pattern is formed on the silicon oxide film by lithography.
  • the silicon oxide film is selectively etched by dry etching using a mixed gas of SF6 gas and a gas containing carbon and fluorine such as C2F6 . Subsequently, the remaining resist pattern is removed by, for example, ashing with ozone. As a result, a mask pattern 15 made of a silicon oxide film having a rectangular cross section is formed.
  • Step 4 by dry etching using a gas containing carbon and fluorine such as CF 4 gas, a mask pattern 15 made of a silicon oxide film is used to hide the amorphous Si thin film 13_1, thereby forming an optical waveguide made of amorphous silicon having a rectangular cross section. A core 13 is formed.
  • an upper clad layer 14 made of silicon oxide is formed by plasma CVD to cover the optical waveguide core 13 (step 5).
  • the SiO 2 mask pattern 15 may or may not be removed before forming the upper clad layer 14 . If not removed, the remaining SiO 2 mask pattern 15 forms the upper cladding layer together with the overlying upper cladding layer 14 .
  • a deuterated (deuterium-containing) gas as a material gas for film formation.
  • the upper cladding layer 14 has silicon oxide containing deuterium.
  • the upper cladding layer 14 may be entirely made of silicon oxide (SiO 2 ) containing deuterium, or may partially contain silicon oxide (SiO 2 ) containing hydrogen.
  • a high-quality film can be formed at a low temperature of 200° C. or less, so the film can be formed without damaging the optical waveguide core made of amorphous Si during film formation.
  • amorphous Si containing deuterium for the core is explained below. Since amorphous Si has a large optical loss due to light absorption by dangling bonds, it is difficult to practically use amorphous Si for waveguide cores.
  • deuterium in amorphous Si and terminating dangling bonds with deuterium by including deuterium in amorphous Si and terminating dangling bonds with deuterium, light absorption can be suppressed and light loss can be reduced.
  • deuterium since deuterium has a stronger bond with the dangling bonds of amorphous Si than hydrogen, the deuterium-terminated dangling bonds are maintained even when external energy is input. As a result, optical losses do not increase.
  • an optical waveguide that does not lose light due to temperature rise in the fabrication process of optical integrated devices can be realized by using amorphous Si containing deuterium for the core.
  • an optical waveguide with high heat resistance, stability, and low loss is realized by using amorphous Si containing deuterium as the optical waveguide core.
  • amorphous Si containing deuterium as the optical waveguide core.
  • SiO 2 containing deuterium as a clad, it is possible to realize an optical waveguide with higher heat resistance, stability, and low loss.
  • this optical waveguide can be applied to an optical integrated device, and high performance of the optical integrated device can be realized.
  • the optical waveguide core is made of amorphous Si containing deuterium, but the optical waveguide core may partially contain amorphous Si or Si (crystal) that does not contain deuterium.
  • the optical waveguide core may have amorphous Si containing deuterium.
  • FIG. 5 and 6 An optical waveguide according to a second embodiment of the present invention will be described with reference to FIGS. 5 and 6.
  • FIG. The optical waveguide 20 and its manufacturing method according to the present embodiment are substantially the same as those of the first embodiment, but differ in the configuration of the optical waveguide core.
  • the optical waveguide 20 includes, in order, a Si (silicon) substrate 21, a SiO2 layer (lower clad layer) 22, an optical waveguide core 23, and an optical waveguide core 23. and an overlying upper cladding layer 24 .
  • the optical waveguide core 23 is made of amorphous Si, and has a width of approximately 300 to 500 nm and a thickness of approximately 200 to 300 nm, for example.
  • the cladding layer 24 is made of SiO 2 and has a thickness of, for example, about 2 to 3 ⁇ m.
  • the optical waveguide core 23 sequentially comprises a lower core 231 in contact with the SiO 2 layer 22 and an upper core 232 .
  • the lower core 231 does not contain deuterium D
  • the upper core 232 contains deuterium D.
  • Amorphous Si containing high deuterium can be formed on the lower cladding layer 22 .
  • the upper core 232 is made thicker than the lower core 231 so that light is guided through the upper core 232 mainly containing deuterium.
  • the thicknesses of the lower core 231 and the upper core 232 can be controlled by adjusting the time to start introducing deuterium and the sputtering time in the manufacturing method described later.
  • a silicon substrate 103 having a thermal oxide film of 3 ⁇ m formed thereon is placed on a sample table 104 in a chamber 101.
  • the silicon substrate 103 corresponds to the silicon substrate 21 in the optical waveguide 20 and the thermal oxide film corresponds to the lower clad layer (SiO 2 ) 22 .
  • a shutter is installed directly above the sample table 104 and the shutter is closed (a state in which the plasma is blocked).
  • argon gas which is an inert gas
  • the inert gas introduction unit 111 is introduced from the inert gas introduction unit 111 at a flow rate of 20 sccm, and the pressure in the plasma generation chamber 102 is set to about 10 to 3 Pa. do.
  • ECR electron cyclotron resonance
  • the shutter is opened to irradiate the substrate 103 with plasma to start forming an amorphous Si film on the substrate 103 for a predetermined time, for example, about 2 minutes (for example, during the film forming time of 10 nm thick amorphous Si). equivalent) is maintained (step 2_221).
  • deuterium is introduced from the gas introduction part 112 at a flow rate of 5 sccm and maintained for a predetermined time, for example, about 15 minutes (step 2_222). Then close the shutter. As a result, amorphous Si containing deuterium is continuously formed on the 10 nm-thick amorphous Si to a total thickness of 200 nm.
  • step 2_23 the microwave and magnetic field are stopped to stop plasma generation.
  • the introduction of the gas is stopped, and the substrate is taken out from the chamber after a predetermined time has passed.
  • An optical waveguide is manufactured in the same steps as in the first embodiment using the amorphous Si film formed in the steps 2_21 to 2_23 described above.
  • the stability of the optical waveguide core is made of amorphous Si containing deuterium, which has excellent adhesion to the lower clad layer and the substrate, and has low loss. It is possible to realize an optical waveguide with a high Furthermore, this optical waveguide can be applied to an optical integrated device, and high performance of the optical integrated device can be realized.
  • the upper core of the optical waveguide core is made of amorphous Si containing deuterium
  • the upper core may partially contain amorphous Si or Si (crystal) that does not contain deuterium.
  • the upper core may have amorphous Si containing deuterium.
  • the lower core of the optical waveguide core is made of amorphous Si that does not contain deuterium
  • the lower core may also contain amorphous Si or Si (crystal) that partially contains deuterium.
  • the lower core may have amorphous Si that does not contain deuterium.
  • SiN x silicon nitride
  • SiN x O y silicon nitride
  • Any dielectric material may be used as long as it has a dielectric constant lower than the dielectric constant of amorphous Si, which is the optical waveguide core, and can confine guided light in the optical waveguide core.
  • argon gas is used as an inert gas in the embodiment of the present invention
  • a rare gas such as xenon or krypton may be used.
  • the present invention is not limited to this.
  • Other materials may be used for the substrate.
  • a glass substrate such as quartz may be used.
  • the substrate since the substrate becomes the lower clad layer, it is not necessary to form a lower clad layer made of SiO2 or the like on the substrate.
  • a Si substrate having an oxide film on its surface as a lower cladding layer is installed in a film forming apparatus, but the present invention is not limited to this, and a substrate (for example, a Si substrate) is installed in a film forming apparatus. Then, a lower clad layer may be formed on the substrate by a film forming apparatus.
  • the shutter is used in the film forming apparatus in the second embodiment, but of course the shutter may be used in the film forming apparatus in the first embodiment.
  • the present invention can be applied to silicon photonics devices and can be applied to devices for optical communication systems.

Abstract

A method for producing an optical waveguide according to the present invention includes: a step for generating plasma of deuterium gas and inert gas; a step for causing sputtering by irradiating a silicon target with plasma; a step for depositing, on a lower clad layer (12), silicon particles generated by the sputtering and forming an amorphous silicon film that contains deuterium; a step for processing the amorphous silicon film into an optical waveguide core (13); and a step for forming an upper clad layer (14) so as to cover the optical waveguide core (13).　Accordingly, the method for producing an optical waveguide according to the present invention enables provision of an optical waveguide that uses amorphous silicon which exhibits a small optical loss and high stability.

Description

光導波路およびその製造方法Optical waveguide and its manufacturing method
　本発明は、アモルファスシリコンを用いる光導波路およびその製造方法に関する。 The present invention relates to an optical waveguide using amorphous silicon and a manufacturing method thereof.
　近年のシリコン・フォトニクス技術の進展により、高屈折率のシリコン導波路を利用して極めて微細で急な曲がりにおいても低損失で光伝搬できる導波路作製技術が開発され、電子デバイスと材料調和性がよいシリコン導波路を利用した光デバイスをシリコン基板上で電子デバイスと集積することで小型光電融合デバイスの実現が可能になってきた。この光電融合技術は、通信の分野においてもデバイスの高速かつ小型化、低消費電力化、低コスト化を実現する鍵となる技術として重要性が高まっている。さらに、シリコン導波路は屈折率が同程度の化合物半導体の発光デバイスや受光デバイスとの光結合にも適しており、シリコン基板と化合物半導体基板を接合することで、シリコンチップ上に光送受信ユニットを集積化する技術開発も進んでいる。 Recent advances in silicon photonics technology have led to the development of waveguide fabrication technology that uses high-refractive-index silicon waveguides to allow light to propagate with low loss even in extremely fine and sharp bends, and has achieved compatibility with electronic devices and materials. By integrating optical devices using good silicon waveguides with electronic devices on a silicon substrate, it has become possible to realize compact optoelectronic devices. This optoelectronics convergence technology is gaining importance as a key technology for realizing high speed, miniaturization, low power consumption, and low cost of devices in the field of communication. Furthermore, silicon waveguides are also suitable for optical coupling with light-emitting devices and light-receiving devices made of compound semiconductors with similar refractive indices. Technology development for integration is also progressing.
　一方、これまでシリコン導波路はＳＯＩ基板上の結晶シリコンを用いて開発されてきたが、結晶シリコンは光損失が小さい利点があるが、ＳＯＩ基板の利用はデバイス集積作製プロセスの自由度が小さくなり、また基板の価格を高価で、集積の効率性やコスト面で課題があった。一般的に光損失が大きいアモルファスシリコンにおいても水素を含有させることで低損失な光導波路が実現できることが示され、これにより高価なＳＯＩ基板上の結晶シリコンを使わずに、低コストでシリコン導波路を利用した光電融合デバイスが作製できる可能性が見えてきた（特許文献１参照）。 On the other hand, until now, silicon waveguides have been developed using crystalline silicon on SOI substrates. Although crystalline silicon has the advantage of low optical loss, the use of SOI substrates reduces the degree of freedom in device integration fabrication processes. In addition, the cost of the substrate was high, and there were problems in terms of integration efficiency and cost. It has been shown that a low-loss optical waveguide can be realized by adding hydrogen even to amorphous silicon, which generally has a large optical loss. The possibility of producing an optoelectronic device utilizing the has emerged (see Patent Document 1).
特開２０１４－３５４９８号公報JP 2014-35498 A
　しかしながら、また水素含有のアモルファスシリコンは、４００℃以上の高温プロセスにおいて、Ｓｉ－Ｈのボンドが切れて導波損失が増大することが明らかになり、発光デバイスや受光デバイスと集積するための作製プロセス中に導波路特性が劣化し、高性能光集積デバイスへの適用が難しいという問題が残っていた。 However, in hydrogen-containing amorphous silicon, it has become clear that in a high temperature process of 400° C. or higher, Si—H bonds are broken and waveguide loss increases. However, there remains the problem of deterioration in waveguide characteristics and difficulty in application to high-performance optical integrated devices.
　本発明は、この問題を解消するためになされたものであり、光損失が小さく、熱耐性が高く、安定性が高いアモルファスシリコンを用いる光導波路とその製造方法を実現することを目的とする。 The present invention was made to solve this problem, and aims to realize an optical waveguide using amorphous silicon with low optical loss, high heat resistance, and high stability, and a manufacturing method thereof.
　上述したような課題を解決するために、本発明に係る光導波路の製造方法は、不活性ガスと重水素ガスのプラズマを発生させる工程と、前記プラズマをシリコンターゲットに照射して、スパッタリングを起こす工程と、前記スパッタリングにより生じたシリコン粒子を、下部クラッド層上に堆積させ、重水素含むアモルファスシリコン膜を成膜する工程と、前記アモルファスシリコン膜を光導波路コアに加工する工程と、前記光導波路コアを覆うように上部クラッド層を形成する工程とを備える。 In order to solve the above-described problems, a method for manufacturing an optical waveguide according to the present invention includes steps of generating plasma of an inert gas and deuterium gas, and irradiating a silicon target with the plasma to cause sputtering. depositing silicon particles generated by the sputtering on the lower clad layer to form an amorphous silicon film containing deuterium; processing the amorphous silicon film into an optical waveguide core; and forming an upper cladding layer over the core.
　また、本発明に係る光導波路の製造方法は、不活性ガスのプラズマを、シリコンターゲットに照射して、スパッタリングを起こす工程と、前記スパッタリングにより生じたシリコン粒子を、下部クラッド層上に堆積させ、第１のアモルファスシリコン膜を成膜する工程と、前記プラズマに重水素ガスを導入して、第２のアモルファスシリコン膜を成膜する工程と、前記第１のアモルファスシリコン膜と前記第２のアモルファスシリコン膜を光導波路コアに加工する工程と、前記光導波路コアを覆うように上部クラッド層を形成する工程とを備える。 Further, the method for manufacturing an optical waveguide according to the present invention includes the steps of irradiating a silicon target with plasma of an inert gas to cause sputtering, depositing silicon particles generated by the sputtering on a lower clad layer, forming a first amorphous silicon film; introducing deuterium gas into the plasma to form a second amorphous silicon film; forming the first amorphous silicon film and the second amorphous silicon film; The method includes a step of processing a silicon film into an optical waveguide core, and a step of forming an upper clad layer so as to cover the optical waveguide core.
　また、本発明に係る光導波路は、順に、下部クラッド層と、重水素を含むアモルファスシリコンを有する光導波路コアと、前記光導波路コアを覆う上部クラッド層とを備える。 Further, an optical waveguide according to the present invention includes, in order, a lower clad layer, an optical waveguide core having amorphous silicon containing deuterium, and an upper clad layer covering the optical waveguide core.
　本発明によれば、光損失が小さく安定性が高いアモルファスシリコンを用いる光導波路およびその製造方法を提供できる。 According to the present invention, an optical waveguide using amorphous silicon with low optical loss and high stability and a manufacturing method thereof can be provided.
図１は、本発明の第１の実施の形態に係る光導波路の構成を示す断面概要図である。FIG. 1 is a schematic cross-sectional view showing the configuration of an optical waveguide according to a first embodiment of the present invention. 図２は、本発明の第１の実施の形態に係る光導波路の製造方法における成膜装置の構成を示す断面概要図である。FIG. 2 is a schematic cross-sectional view showing the configuration of a film forming apparatus in the optical waveguide manufacturing method according to the first embodiment of the present invention. 図３は、本発明の第１の実施の形態に係る光導波路の製造方法における成膜方法のフローチャート図である。FIG. 3 is a flowchart of a film forming method in the optical waveguide manufacturing method according to the first embodiment of the present invention. 図４は、本発明の第１の実施の形態に係る光導波路の製造方法を説明するための図である。FIG. 4 is a diagram for explaining the method of manufacturing the optical waveguide according to the first embodiment of the present invention. 図５は、本発明の第２の実施の形態に係る光導波路の構成を示す断面概要図である。FIG. 5 is a schematic cross-sectional view showing the configuration of an optical waveguide according to a second embodiment of the invention. 図６は、本発明の第２の実施の形態に係る光導波路の製造方法における成膜方法のフローチャート図である。FIG. 6 is a flow chart of a film forming method in the optical waveguide manufacturing method according to the second embodiment of the present invention.
＜第１の実施の形態＞
　本発明の第１の実施の形態に係る光導波路について図１～図４を参照して説明する。 <First embodiment>
An optical waveguide according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.
＜光導波路の構成＞
　本実施の形態に係る光導波路１０は、図１に示すように、順に、シリコン（Ｓｉ）基板１１と、下部クラッド（ＳｉＯ２）層１２と、光導波路コア１３と、光導波路コア１３を覆うクラッド層１４とを備える。 <Structure of Optical Waveguide>
As shown in FIG. 1, the optical waveguide 10 according to the present embodiment sequentially covers a silicon (Si) substrate 11, a lower clad (SiO 2 ) layer 12, an optical waveguide core 13, and an optical waveguide core 13. and a cladding layer 14 .
　光導波路コア１３は、重水素を含むアモルファスＳｉからなり、例えば、幅は３００～５００ｎｍ程度、厚さは２００～３００ｎｍ程度である。 The optical waveguide core 13 is made of amorphous Si containing deuterium, and has a width of about 300 to 500 nm and a thickness of about 200 to 300 nm, for example.
　クラッド層１４はＳｉＯ２からなり、例えば、厚さは２～３μｍ程度である。 The clad layer 14 is made of SiO 2 and has a thickness of about 2 to 3 μm, for example.
＜光導波路の製造方法＞
　本実施の形態に係る光導波路１０の材料の成膜に用いる装置を説明する。 <Method for manufacturing an optical waveguide>
An apparatus used for film formation of the material of the optical waveguide 10 according to this embodiment will be described.
　図２に、本実施の形態で成膜装置として用いるＥＣＲスパッタ装置の一例の断面図を示す。ＥＣＲスパッタ装置１００により、光導波路のコア材料となるアモルファスＳｉ薄膜を成膜する。 FIG. 2 shows a cross-sectional view of an example of an ECR sputtering apparatus used as a film forming apparatus in this embodiment. An amorphous Si thin film, which will be the core material of the optical waveguide, is deposited by the ECR sputtering apparatus 100 .
　ＥＣＲスパッタ装置１００は、順に、チャンバー１０１と、プラズマ生成室１０２と、真空導波管１０６と、導波管１０８と備え、それぞれは連通されている。 The ECR sputtering apparatus 100 includes, in order, a chamber 101, a plasma generation chamber 102, a vacuum waveguide 106, and a waveguide 108, which are in communication with each other.
　チャンバー１０１は、真空排気装置（図示せず）に連通し、真空排気装置によりプラズマ生成室１０２とともに内部が真空排気される。 The chamber 101 communicates with an evacuation device (not shown), and the inside thereof together with the plasma generation chamber 102 is evacuated by the evacuation device.
　チャンバー１０１には、膜形成対象の基板１０３が固定される試料台１０４が設けられている。試料台１０４は、所望の角度に傾斜し、かつ回転する。試料台１０４は、回転機構（図示せず）により回転可能とされている。 The chamber 101 is provided with a sample table 104 on which a substrate 103 on which a film is to be formed is fixed. The sample stage 104 tilts and rotates at a desired angle. The sample table 104 is rotatable by a rotating mechanism (not shown).
　また、チャンバー１０１内の、プラズマ生成室１０２からのプラズマが導入される開口領域において、開口領域を取り巻くようにリング状のシリコンターゲット１０５が備えられている。シリコンターゲット１０５は、絶縁体からなる容器１０５ａ内に載置され、内側の面がチャンバー１０１内に露出している。 In addition, a ring-shaped silicon target 105 is provided so as to surround the opening region in the chamber 101 where the plasma from the plasma generation chamber 102 is introduced. The silicon target 105 is placed in a container 105 a made of an insulator, and the inner surface is exposed inside the chamber 101 .
　また、プラズマ生成室１０２は、真空導波管１０６に連通し、真空導波管１０６は、石英窓１０７を介して導波管１０８に接続されている。導波管１０８は、マイクロ波発生部（図示せず）に連通している。これらの、マイクロ波発生部と、導波管１０８と、石英窓１０７と、真空導波管１０６により、マイクロ波供給手段が構成されている。 Also, the plasma generation chamber 102 communicates with a vacuum waveguide 106 , and the vacuum waveguide 106 is connected to a waveguide 108 via a quartz window 107 . Waveguide 108 communicates with a microwave generator (not shown). The microwave generator, the waveguide 108, the quartz window 107, and the vacuum waveguide 106 constitute microwave supply means.
　また、プラズマ生成室１０２の周囲及びプラズマ生成室１０２の上部に、磁気コイル１１０が備えられている。なお、導波管１０８の途中に、モード変換器を設けるようにする構成もある。 A magnetic coil 110 is also provided around and above the plasma generation chamber 102 . Note that there is also a configuration in which a mode converter is provided in the middle of the waveguide 108 .
　次に、上述のＥＣＲスパッタ装置１００を用いた、本実施の形態におけるアモルファスＳｉ膜の成膜方法について説明する。 Next, a method for forming an amorphous Si film according to the present embodiment using the ECR sputtering apparatus 100 described above will be described.
　まず、チャンバー１０１内の試料台１０４に熱酸化膜３μｍが形成されているシリコン基板１０３を設置する。ここで、シリコン基板１０３は光導波路１０におけるシリコン基板１１に相当し、熱酸化膜は下部クラッド層（ＳｉＯ２）１２に相当する。 First, a silicon substrate 103 on which a 3 μm thick thermal oxide film is formed is placed on a sample table 104 in a chamber 101 . Here, the silicon substrate 103 corresponds to the silicon substrate 11 in the optical waveguide 10 and the thermal oxide film corresponds to the lower clad layer (SiO 2 ) 12 .
　次に、チャンバー１０１及びプラズマ生成室１０２内を真空排気した後、不活性ガス導入部１１１よりプラズマ生成室１０２に、不活性ガスであるアルゴンガスを導入する。 Next, after the chamber 101 and the plasma generation chamber 102 are evacuated, argon gas, which is an inert gas, is introduced into the plasma generation chamber 102 from the inert gas introduction unit 111 .
　また、不活性ガス導入部とは別に設置されたガス導入部１１２より、チャンバー１０１に重水素を導入し、プラズマ生成室１０２内を例えば１０－３Ｐａ程度の圧力にする。 Further, deuterium is introduced into the chamber 101 through a gas introduction section 112 installed separately from the inert gas introduction section, and the pressure inside the plasma generation chamber 102 is set to about 10-3 Pa, for example.
　この状態で、磁気コイル１１０よりプラズマ生成室１０２内に８７５Ｇの磁場を発生させた後、導波管１０８、石英窓１０７を介してプラズマ生成室１０２内に２．４５ＧＨｚのマイクロ波を導入し、電子サイクロトロン共鳴（ＥＣＲ）プラズマを発生させる（ステップ２＿１１）。 In this state, after a magnetic field of 875 G was generated in the plasma generation chamber 102 by the magnetic coil 110, microwaves of 2.45 GHz were introduced into the plasma generation chamber 102 via the waveguide 108 and the quartz window 107, An electron cyclotron resonance (ECR) plasma is generated (step 2_11).
　ＥＣＲプラズマは、磁気コイル１１０からの発散磁場により、試料台１０４の方向にプラズマ流を形成する。 The ECR plasma forms a plasma flow in the direction of the sample stage 104 due to the divergent magnetic field from the magnetic coil 110 .
　ここで、本実施の形態におけるＥＣＲスパッタ装置１００では、マイクロ波発生部より供給されたマイクロ波電力を、導波管１０８において分岐し、プラズマ生成室１０２上部の真空導波管１０６に、プラズマ生成室１０２から石英窓１０７を介して結合させている。この構成により、石英窓１０７に対するシリコンターゲット１０５からの飛散粒子の付着を防ぐことができ、ランニングタイムを大幅に改善できる。 Here, in the ECR sputtering apparatus 100 according to the present embodiment, the microwave power supplied from the microwave generation unit is branched at the waveguide 108, and the plasma generation is performed in the vacuum waveguide 106 above the plasma generation chamber 102. It is coupled from chamber 102 through quartz window 107 . This configuration can prevent scattering particles from the silicon target 105 from adhering to the quartz window 107, and can greatly improve the running time.
　このようにプラズマが生成された状態で、プラズマ生成室１０２と試料台１０４との間に設けたリング状のシリコンターゲット１０５に高周波電圧を印加することにより、シリコンターゲット１０５表面にプラズマを引き寄せて照射して、スパッタリングを起こす。 In the state where the plasma is generated in this manner, a high-frequency voltage is applied to the ring-shaped silicon target 105 provided between the plasma generation chamber 102 and the sample table 104, thereby attracting the plasma to the surface of the silicon target 105 and irradiating it. to cause sputtering.
　このスパッタリングにより、シリコンターゲット１０５表面よりターゲット材料（シリコン）の粒子が飛び出し、プラズマ生成室１０２より放出されたプラズマとともに基板１０３上に到達する。 By this sputtering, particles of the target material (silicon) fly out from the surface of the silicon target 105 and reach the substrate 103 together with the plasma emitted from the plasma generation chamber 102 .
　また、上記粒子とともに、プラズマにより活性化された重水素ガスも基板１０３上に到達する。この結果、基板１０３上に重水素を含むアモルファスＳｉが堆積し、基板１０３の熱酸化膜上にアモルファスＳｉ膜が成膜される（ステップ２＿１２）。 In addition, deuterium gas activated by plasma also reaches the substrate 103 together with the particles. As a result, amorphous Si containing deuterium is deposited on the substrate 103, and an amorphous Si film is formed on the thermal oxide film of the substrate 103 (step 2_12).
　ここで、成膜レートを事前に確認し、スパッタ時間を制御することで成膜する膜厚を制御できる。例えば、成膜されるアモルファスＳｉの膜厚が２００ｎｍになったところでスパッタリングを停止する（ステップ２＿１３）。その結果、３μｍの熱酸化膜上に２００ｎｍ厚さのアモルファスＳｉが成膜される。 Here, the film thickness to be deposited can be controlled by checking the deposition rate in advance and controlling the sputtering time. For example, the sputtering is stopped when the film thickness of the amorphous Si to be deposited reaches 200 nm (step 2_13). As a result, an amorphous Si film with a thickness of 200 nm is formed on the thermal oxide film with a thickness of 3 μm.
　次に、上述のアモルファスＳｉ膜を用いた光導波路の製造方法について説明する。 Next, a method for manufacturing an optical waveguide using the amorphous Si film described above will be described.
　初めに、シリコン基板１１上に酸化膜（ＳｉＯ２）１２を形成する（ステップ１） First, an oxide film (SiO 2 ) 12 is formed on a silicon substrate 11 (step 1).
　次に、上述の成膜方法により、酸化膜（ＳｉＯ２）１２に、アモルファスＳｉ薄膜１３＿１を形成する（ステップ２） Next, an amorphous Si thin film 13_1 is formed on the oxide film (SiO 2 ) 12 by the film forming method described above (step 2).
　次に、通常のリソグラフィ技術により、アモルファスＳｉ薄膜１３＿１上に、ＳｉＯ２のマスクパターン１５を形成する（ステップ３）。 Next, a mask pattern 15 of SiO 2 is formed on the amorphous Si thin film 13_1 by a normal lithographic technique (step 3).
　例えば、まず、アモルファスＳｉ薄膜の上に、プラズマＣＶＤ法によりにシリコン酸化膜を形成する。引き続き、リソグラフィ技術によりシリコン酸化膜上にレジストによるマスクパターンを形成する。 For example, first, a silicon oxide film is formed on an amorphous Si thin film by plasma CVD. Subsequently, a resist mask pattern is formed on the silicon oxide film by lithography.
　次に、Ｃ２Ｆ６などカーボンとフッ素を含むガスとＳＦ６ガスの混合ガスを用いたドライエッチングによりシリコン酸化膜を選択的にエッチングする。引き続き、残存するレジストパターンを、例えばオゾンよるアッシングで除去する。その結果、断面を矩形とするシリコン酸化膜からなるマスクパターン１５が形成される。 Next, the silicon oxide film is selectively etched by dry etching using a mixed gas of SF6 gas and a gas containing carbon and fluorine such as C2F6 . Subsequently, the remaining resist pattern is removed by, for example, ashing with ozone. As a result, a mask pattern 15 made of a silicon oxide film having a rectangular cross section is formed.
　次に、ＣＦ４ガスなどカーボンとフッ素含むガスを用いたドライエッチングにより、シリコン酸化膜からなるマスクパターン１５を用いて、アモルファスＳｉ薄膜１３＿１を隠して、断面を矩形とするアモルファスシリコンからなる光導波路コア１３を形成する。（ステップ４） Next, by dry etching using a gas containing carbon and fluorine such as CF 4 gas, a mask pattern 15 made of a silicon oxide film is used to hide the amorphous Si thin film 13_1, thereby forming an optical waveguide made of amorphous silicon having a rectangular cross section. A core 13 is formed. (Step 4)
　最後に、プラズマＣＶＤ法によって光導波路コア１３を覆うように酸化シリコンからなる上部クラッド層１４を形成する（ステップ５）。このとき、上部クラッド層１４の形成前に、ＳｉＯ２マスクパターン１５を除去してよいし、除去しなくてもよい。除去しない場合には、残存するＳｉＯ２マスクパターン１５は、積層される上部クラッド層１４とともに、上部クラッド層を形成する。 Finally, an upper clad layer 14 made of silicon oxide is formed by plasma CVD to cover the optical waveguide core 13 (step 5). At this time, the SiO 2 mask pattern 15 may or may not be removed before forming the upper clad layer 14 . If not removed, the remaining SiO 2 mask pattern 15 forms the upper cladding layer together with the overlying upper cladding layer 14 .
　ここで、上部クラッド層１４に水素が含まれると、膜中にＯＨ基ができて光吸収による光損失が発生する。そこで、上部クラッド層１４の形成に用いるプラズマＣＶＤ法において、成膜の材料ガスに重水素化した（重水素を含む）ガスを用いることが望ましい。 Here, if hydrogen is contained in the upper clad layer 14, OH groups are formed in the film, causing light loss due to light absorption. Therefore, in the plasma CVD method used to form the upper clad layer 14, it is desirable to use a deuterated (deuterium-containing) gas as a material gas for film formation.
　その結果、上部クラッド層１４は重水素を含む酸化シリコンを有する。ここで、上部クラッド層１４全てが重水素を含む酸化シリコン（ＳｉＯ２）であってもよく、一部に水素を含む酸化シリコン（ＳｉＯ２）を含んでもよい。 As a result, the upper cladding layer 14 has silicon oxide containing deuterium. Here, the upper cladding layer 14 may be entirely made of silicon oxide (SiO 2 ) containing deuterium, or may partially contain silicon oxide (SiO 2 ) containing hydrogen.
　また、プラズマＣＶＤ法としてＥＣＲプラズマＣＶＤ法を用いれば、２００℃以下の低温で良質な膜が形成できるので、成膜中にアモルファスＳｉからなる光導波路コアに損傷を与えることなく成膜できる。 Also, if the ECR plasma CVD method is used as the plasma CVD method, a high-quality film can be formed at a low temperature of 200° C. or less, so the film can be formed without damaging the optical waveguide core made of amorphous Si during film formation.
　重水素を含むアモルファスＳｉをコアに用いる理由を、以下に説明する。アモルファスＳｉではダングリングボンドの光吸収により光損失が大きいため、アモルファスＳｉを実用的に導波路コアに用いることは困難である。 The reason for using amorphous Si containing deuterium for the core is explained below. Since amorphous Si has a large optical loss due to light absorption by dangling bonds, it is difficult to practically use amorphous Si for waveguide cores.
　ここで、アモルファスＳｉに水素を含有させ、ダングリングボンドを水素で終端化することにより、光吸収を抑制して光損失を低減することができる。しかしながら、水素で終端化されたアモルファスＳｉが加熱されたり強い光の照射を受けたりすると、外部エネルギーにより終端化された水素がはずれて光吸収が増加する。 Here, by including hydrogen in amorphous Si and terminating dangling bonds with hydrogen, light absorption can be suppressed and light loss can be reduced. However, when hydrogen-terminated amorphous Si is heated or irradiated with strong light, the hydrogen-terminated hydrogen atoms are removed by external energy, increasing light absorption.
　一方、アモルファスＳｉに重水素を含有させ、ダングリングボンドを重水素で終端化することにより、光吸収を抑制して光損失を低減することができる。この場合、重水素の方が水素よりもアモルファスＳｉのダングリングボンドとの結合が強いため、外部エネルギーが入力されても、重水素で終端化されたダングリングボンドが維持される。その結果、光損失は増加しない。 On the other hand, by including deuterium in amorphous Si and terminating dangling bonds with deuterium, light absorption can be suppressed and light loss can be reduced. In this case, since deuterium has a stronger bond with the dangling bonds of amorphous Si than hydrogen, the deuterium-terminated dangling bonds are maintained even when external energy is input. As a result, optical losses do not increase.
　このように、光集積デバイス作製プロセスにおける温度上昇により光損失しない光導波路を、重水素を含むアモルファスＳｉをコアに用いることにより実現できる。 In this way, an optical waveguide that does not lose light due to temperature rise in the fabrication process of optical integrated devices can be realized by using amorphous Si containing deuterium for the core.
　以上のように、本実施の形態に係る光導波路およびその製造方法によれば、重水素を含むアモルファスＳｉを光導波路コアとすることにより、熱耐性が高く、安定で低損失な光導波路を実現できる。また、重水素を含むＳｉＯ２をクラッドとすることにより、さらに熱耐性が高く、安定で低損失な光導波路を実現できる。さらに、この光導波路を光集積デバイスに適用でき、光集積デバイスの高性能化が実現できる。 As described above, according to the optical waveguide and the manufacturing method thereof according to the present embodiment, an optical waveguide with high heat resistance, stability, and low loss is realized by using amorphous Si containing deuterium as the optical waveguide core. can. In addition, by using SiO 2 containing deuterium as a clad, it is possible to realize an optical waveguide with higher heat resistance, stability, and low loss. Furthermore, this optical waveguide can be applied to an optical integrated device, and high performance of the optical integrated device can be realized.
　本実施の形態では、光導波路コアが重水素を含むアモルファスＳｉからなる例を示したが、光導波路コアは一部に重水素を含まないアモルファスＳｉやＳｉ（結晶）を含んでもよい。光導波路コアは重水素を含むアモルファスＳｉを有すればよい。 In this embodiment, an example in which the optical waveguide core is made of amorphous Si containing deuterium is shown, but the optical waveguide core may partially contain amorphous Si or Si (crystal) that does not contain deuterium. The optical waveguide core may have amorphous Si containing deuterium.
＜第２の実施の形態＞
　本発明の第２の実施の形態に係る光導波路について図５～図６を参照して説明する。本実施の形態に係る光導波路２０およびその製造方法は、第１の実施の形態と略同様であるが、光導波路コアの構成が異なる。 <Second Embodiment>
An optical waveguide according to a second embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG. The optical waveguide 20 and its manufacturing method according to the present embodiment are substantially the same as those of the first embodiment, but differ in the configuration of the optical waveguide core.
＜光導波路の構成＞
　本実施の形態に係る光導波路２０は、図５に示すように、順に、Ｓｉ（シリコン）基板２１と、ＳｉＯ２層（下部クラッド層）２２と、光導波路コア２３と、光導波路コア２３を覆う上部クラッド層２４とを備える。光導波路コア２３はアモルファスＳｉからなり、例えば、幅は３００～５００ｎｍ程度、厚さは２００～３００ｎｍ程度である。また、クラッド層２４はＳｉＯ２からなり、例えば、厚さは２～３μｍ程度である。 <Structure of Optical Waveguide>
As shown in FIG. 5, the optical waveguide 20 according to the present embodiment includes, in order, a Si (silicon) substrate 21, a SiO2 layer (lower clad layer) 22, an optical waveguide core 23, and an optical waveguide core 23. and an overlying upper cladding layer 24 . The optical waveguide core 23 is made of amorphous Si, and has a width of approximately 300 to 500 nm and a thickness of approximately 200 to 300 nm, for example. The cladding layer 24 is made of SiO 2 and has a thickness of, for example, about 2 to 3 μm.
　光導波路コア２３は、順に、ＳｉＯ２層２２と接する下部コア２３１と、上部コア２３２とを備える。下部コア２３１は重水素Ｄを含まず、上部コア２３２は重水素Ｄを含む。このように、下部クラッド層２２と上部コア２３２との間に、重水素Ｄを含まない下部コア２３１を有することにより、光導波路コア２３の下部クラッド層２２への密着性が向上し、密着性の高い重水素を含むアモルファスＳｉを下部クラッド層２２上に形成できる。 The optical waveguide core 23 sequentially comprises a lower core 231 in contact with the SiO 2 layer 22 and an upper core 232 . The lower core 231 does not contain deuterium D, and the upper core 232 contains deuterium D. Thus, by having the lower core 231 that does not contain deuterium D between the lower clad layer 22 and the upper core 232, the adhesion of the optical waveguide core 23 to the lower clad layer 22 is improved. Amorphous Si containing high deuterium can be formed on the lower cladding layer 22 .
　ここで、光が主に重水素を含む上部コア２３２を導波するように、上部コア２３２を下部コア２３１より厚くする。下部コア２３１と上部コア２３２の厚さは、後述する製造方法において重水素の導入を開始する時間とスパッタの時間とを調整することで制御できる。 Here, the upper core 232 is made thicker than the lower core 231 so that light is guided through the upper core 232 mainly containing deuterium. The thicknesses of the lower core 231 and the upper core 232 can be controlled by adjusting the time to start introducing deuterium and the sputtering time in the manufacturing method described later.
＜光導波路の製造方法＞
　本実施の形態におけるアモルファスＳｉ膜の成膜方法について図６を参照して説明する。 <Method for manufacturing an optical waveguide>
A method of forming an amorphous Si film according to this embodiment will be described with reference to FIG.
　ＥＣＲスパッタ装置１００において、チャンバー１０１内の試料台１０４に熱酸化膜３μｍが形成されているシリコン基板１０３を設置する。ここで、シリコン基板１０３は、光導波路２０におけるシリコン基板２１に相当し、熱酸化膜は下部クラッド層（ＳｉＯ２）２２に相当する。 In the ECR sputtering apparatus 100, a silicon substrate 103 having a thermal oxide film of 3 μm formed thereon is placed on a sample table 104 in a chamber 101. As shown in FIG. Here, the silicon substrate 103 corresponds to the silicon substrate 21 in the optical waveguide 20 and the thermal oxide film corresponds to the lower clad layer (SiO 2 ) 22 .
　このとき、プラズマが基板１０３に照射されるのを防ぐために、試料台１０４直上にシャッターを設置して、シャッターを閉じた状態（プラズマをさえぎる状態）とする。 At this time, in order to prevent the substrate 103 from being irradiated with plasma, a shutter is installed directly above the sample table 104 and the shutter is closed (a state in which the plasma is blocked).
　次に、チャンバー１０１及びプラズマ生成室１０２内を真空排気した後、不活性ガス導入部１１１より不活性ガスであるアルゴンガスを流量２０ｓｃｃｍ導入し、プラズマ生成室１０２内を１０～３Ｐａ程度の圧力にする。 Next, after evacuating the chamber 101 and the plasma generation chamber 102, argon gas, which is an inert gas, is introduced from the inert gas introduction unit 111 at a flow rate of 20 sccm, and the pressure in the plasma generation chamber 102 is set to about 10 to 3 Pa. do.
　次に、磁場の発生とマイクロ波の導入により、電子サイクロトロン共鳴（ＥＣＲ）プラズマを発生させる（ステップ２＿２１）。 Next, generate electron cyclotron resonance (ECR) plasma by generating a magnetic field and introducing microwaves (step 2_21).
　次に、プラズマ生成室１０２と試料台１０４との間に設けたリング状のシリコンターゲット１０５に高周波電圧を印加することにより、シリコンターゲット１０５表面にプラズマを引き寄せてスパッタリングを起こす。プラズマが安定するまで、所定の時間、例えば２分間、この状態を維持する。 Next, by applying a high-frequency voltage to the ring-shaped silicon target 105 provided between the plasma generation chamber 102 and the sample table 104, plasma is attracted to the surface of the silicon target 105 to cause sputtering. This state is maintained for a predetermined time, eg, 2 minutes, until the plasma stabilizes.
　次に、シャッターを開き基板１０３にプラズマを照射させ、基板１０３上でのアモルファスＳｉの成膜を開始して、所定の時間、例えば約２分間（例えば、１０ｎｍ厚のアモルファスＳｉの成膜時間に相当）維持する（ステップ２＿２２１）。 Next, the shutter is opened to irradiate the substrate 103 with plasma to start forming an amorphous Si film on the substrate 103 for a predetermined time, for example, about 2 minutes (for example, during the film forming time of 10 nm thick amorphous Si). equivalent) is maintained (step 2_221).
　次に、ガス導入部１１２より重水素を流量５ｓｃｃｍ導入し、所定の時間、例えば１５分間程度維持する（ステップ２＿２２２）。その後、シャッターを閉じる。その結果、１０ｎｍ厚のアモルファスＳｉ上に連続的に重水素を含むアモルファスＳｉが、合計２００ｎｍの厚さで成膜される。 Next, deuterium is introduced from the gas introduction part 112 at a flow rate of 5 sccm and maintained for a predetermined time, for example, about 15 minutes (step 2_222). Then close the shutter. As a result, amorphous Si containing deuterium is continuously formed on the 10 nm-thick amorphous Si to a total thickness of 200 nm.
　最後に、マイクロ波と磁場を停止してプラズマ発生を停止する（ステップ２＿２３）。その後、ガスの導入を停止し、所定の時間が経過した後、基板をチャンバーから取り出す。 Finally, the microwave and magnetic field are stopped to stop plasma generation (step 2_23). After that, the introduction of the gas is stopped, and the substrate is taken out from the chamber after a predetermined time has passed.
　本実施の形態では、アルゴンガスの導入の後に重水素を導入する例を示したが、アルゴンと重水素を同時に導入すれば、下部コア２３１の厚さはゼロとなる。 In the present embodiment, an example of introducing deuterium after introducing argon gas was shown, but if argon and deuterium are introduced simultaneously, the thickness of the lower core 231 becomes zero.
　上述のステップ２＿２１からステップ２＿２３までの工程で成膜されるアモルファスＳｉを用いて、第１の実施の形態と同様の工程で、光導波路を製造する。 An optical waveguide is manufactured in the same steps as in the first embodiment using the amorphous Si film formed in the steps 2_21 to 2_23 described above.
　以上のように、本実施の形態に係る光導波路およびその製造方法によれば、下部クラッド層および基板との密着性に優れ、低損失な重水素を含むアモルファスＳｉを光導波路コアとする安定性が高い光導波路を実現できる。さらに、この光導波路を光集積デバイスに適用でき、光集積デバイスの高性能化が実現できる。 As described above, according to the optical waveguide and the method for manufacturing the same according to the present embodiment, the stability of the optical waveguide core is made of amorphous Si containing deuterium, which has excellent adhesion to the lower clad layer and the substrate, and has low loss. It is possible to realize an optical waveguide with a high Furthermore, this optical waveguide can be applied to an optical integrated device, and high performance of the optical integrated device can be realized.
　本実施の形態では、光導波路コアの上部コアが重水素を含むアモルファスＳｉからなる例を示したが、上部コアは一部に重水素を含まないアモルファスＳｉやＳｉ（結晶）を含んでもよい。上部コアは重水素を含むアモルファスＳｉを有すればよい。 In this embodiment, an example in which the upper core of the optical waveguide core is made of amorphous Si containing deuterium is shown, but the upper core may partially contain amorphous Si or Si (crystal) that does not contain deuterium. The upper core may have amorphous Si containing deuterium.
　本実施の形態では、光導波路コアの下部コアが重水素を含まないアモルファスＳｉからなる例を示したが、下部コアは一部に重水素を含むアモルファスＳｉやＳｉ（結晶）を含んでもよい。下部コアは重水素を含まないアモルファスＳｉを有すればよい。 In this embodiment, an example in which the lower core of the optical waveguide core is made of amorphous Si that does not contain deuterium is shown, but the lower core may also contain amorphous Si or Si (crystal) that partially contains deuterium. The lower core may have amorphous Si that does not contain deuterium.
　本発明の実施の形態では、上部クラッド層および下部クラッド層に酸化シリコン（ＳｉＯ２）を用いる例を示したが、ＳｉＮｘ（窒化シリコン）やＳｉＮｘＯｙを用いてもよい。光導波路コアであるアモルファスＳｉの誘電率より低い誘電率を有し、導波する光を光導波路コアに閉じ込めることができる誘電体であればよい。 Although silicon oxide (SiO 2 ) is used for the upper clad layer and the lower clad layer in the embodiment of the present invention, SiN x (silicon nitride) or SiN x O y may be used. Any dielectric material may be used as long as it has a dielectric constant lower than the dielectric constant of amorphous Si, which is the optical waveguide core, and can confine guided light in the optical waveguide core.
　本発明の実施の形態では、不活性ガスとしてアルゴンガスを用いたが、キセノン、クリプトン等の希ガスを用いてもよい。 Although argon gas is used as an inert gas in the embodiment of the present invention, a rare gas such as xenon or krypton may be used.
　本発明の実施の形態では、シリコン基板を用いる例を示したが、これに限らない。他の材料を基板に用いてもよい。石英などのガラス基板を用いてもよい。この場合は、基板が下部クラッド層になるので、基板上にSiO2等からなる下部クラッド層を形成しなくてもよい。 Although an example using a silicon substrate has been shown in the embodiment of the present invention, the present invention is not limited to this. Other materials may be used for the substrate. A glass substrate such as quartz may be used. In this case, since the substrate becomes the lower clad layer, it is not necessary to form a lower clad layer made of SiO2 or the like on the substrate.
　本発明の実施の形態では、下部クラッド層として表面に酸化膜を有するＳｉ基板を成膜装置に設置する例を示したが、これに限らず、基板（例えばＳｉ基板）を成膜装置に設置して、成膜装置によって基板上に下部クラッド層を形成してもよい。 In the embodiment of the present invention, an example in which a Si substrate having an oxide film on its surface as a lower cladding layer is installed in a film forming apparatus is shown, but the present invention is not limited to this, and a substrate (for example, a Si substrate) is installed in a film forming apparatus. Then, a lower clad layer may be formed on the substrate by a film forming apparatus.
　本発明の実施の形態では、第２の実施の形態において成膜装置でシャッターを用いたが、当然第１の実施の形態において成膜装置でシャッターを用いてもよい。 In the embodiment of the present invention, the shutter is used in the film forming apparatus in the second embodiment, but of course the shutter may be used in the film forming apparatus in the first embodiment.
　本発明の実施の形態では、光導波路の構成、製造方法などにおいて、各構成部の構造、寸法、材料等の一例を示したが、これに限らない。光導波路の機能を発揮し効果を奏するものであればよい。 In the embodiment of the present invention, an example of the structure, dimensions, materials, etc. of each component is shown in the structure of the optical waveguide, the manufacturing method, etc., but the present invention is not limited to this. Any material may be used as long as it exhibits the function of the optical waveguide and produces an effect.
　本発明は、シリコン・フォトニクスデバイスに適用でき、光通信システム用デバイスに適用することができる。 The present invention can be applied to silicon photonics devices and can be applied to devices for optical communication systems.
１０　光導波路
１１　シリコン基板
１２　下部クラッド層
１３　光導波路コア
１４　上部クラッド層 10 Optical waveguide 11 Silicon substrate 12 Lower clad layer 13 Optical waveguide core 14 Upper clad layer

Claims (7)

  1. 　不活性ガスと重水素ガスのプラズマを発生させる工程と、
    　前記プラズマをシリコンターゲットに照射して、スパッタリングを起こす工程と、
    　前記スパッタリングにより生じたシリコン粒子を、下部クラッド層上に堆積させ、重水素含むアモルファスシリコン膜を成膜する工程と、
    　前記アモルファスシリコン膜を光導波路コアに加工する工程と、
    　前記光導波路コアを覆うように上部クラッド層を形成する工程と
    　を備える光導波路の製造方法。     generating a plasma of inert gas and deuterium gas;
    irradiating a silicon target with the plasma to cause sputtering;
    depositing the silicon particles generated by the sputtering on the lower clad layer to form an amorphous silicon film containing deuterium;
    processing the amorphous silicon film into an optical waveguide core;
    and forming an upper clad layer so as to cover the optical waveguide core.
  2. 　不活性ガスのプラズマを、シリコンターゲットに照射して、スパッタリングを起こす工程と、
    　前記スパッタリングにより生じたシリコン粒子を、下部クラッド層上に堆積させ、第１のアモルファスシリコン膜を成膜する工程と、
    　前記プラズマに重水素ガスを導入して、第２のアモルファスシリコン膜を成膜する工程と、
    　前記第１のアモルファスシリコン膜と前記第２のアモルファスシリコン膜を光導波路コアに加工する工程と、
    　前記光導波路コアを覆うように上部クラッド層を形成する工程と
    　を備える光導波路の製造方法。     A step of irradiating a silicon target with plasma of an inert gas to cause sputtering;
    depositing the silicon particles generated by the sputtering on the lower clad layer to form a first amorphous silicon film;
    introducing deuterium gas into the plasma to form a second amorphous silicon film;
    processing the first amorphous silicon film and the second amorphous silicon film into an optical waveguide core;
    and forming an upper clad layer so as to cover the optical waveguide core.
  3. 　前記上部クラッド層を、ＥＣＲプラズマを利用するＣＶＤ法により形成することを特徴とする請求項１又は請求項２に記載の光導波路の製造方法。 The method for manufacturing an optical waveguide according to claim 1 or 2, wherein the upper clad layer is formed by a CVD method using ECR plasma.
  4. 　前記上部クラッド層が、重水素を含むガスを用いて形成される酸化シリコンであることを特徴とする請求項１から請求項３のいずれか一項に記載の光導波路の製造方法。 The method for manufacturing an optical waveguide according to any one of claims 1 to 3, wherein the upper clad layer is silicon oxide formed using a gas containing deuterium.
  5. 　順に、下部クラッド層と、
    　重水素を含むアモルファスシリコンを有する光導波路コアと、
    　前記光導波路コアを覆う上部クラッド層と
    　を備える光導波路。     in turn a lower cladding layer;
    an optical waveguide core having amorphous silicon containing deuterium;
    and an upper clad layer covering the optical waveguide core.
  6. 　前記光導波路コアが、重水素を含むアモルファスシリコンを有する上部層と、
    　重水素を含まないアモルファスシリコンを有する下部層からなり、
    　前記下部層を介して前記下部クラッド層と接することを特徴とする請求項５に記載の光導波路。     a top layer in which the optical waveguide core comprises amorphous silicon containing deuterium;
    consisting of a lower layer having amorphous silicon that does not contain deuterium;
    6. The optical waveguide according to claim 5, wherein the optical waveguide is in contact with the lower clad layer through the lower layer.
  7. 　前記上部クラッド層が、重水素を含む酸化シリコンを有することを特徴とする請求項５又は請求項６に記載の光導波路。 The optical waveguide according to claim 5 or 6, wherein the upper clad layer comprises silicon oxide containing deuterium.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040240821A1 (en) * 2003-05-30 2004-12-02 The Regents Of The University Of California Direct-patterned optical waveguides on amorphous silicon films
US20070147762A1 (en) * 2005-10-07 2007-06-28 Kwakernaak Martin H Interface for a-Si waveguides and III/V waveguides
US20080253728A1 (en) * 2006-09-07 2008-10-16 Massachusetts Institute Of Technology Microphotonic waveguide including core/cladding interface layer
JP2010263153A (en) * 2009-05-11 2010-11-18 Sumitomo Electric Ind Ltd Semiconductor integrated optical device, and method of making the same
WO2019225329A1 (en) * 2018-05-21 2019-11-28 日本電信電話株式会社 Optical integrated device and production method therefor

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3197036B2 (en) * 1991-11-14 2001-08-13 鐘淵化学工業株式会社 Method for forming crystalline silicon thin film
JPH06326030A (en) * 1993-05-13 1994-11-25 Canon Inc Method and apparatus for manufacture semiconductor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040240821A1 (en) * 2003-05-30 2004-12-02 The Regents Of The University Of California Direct-patterned optical waveguides on amorphous silicon films
US20070147762A1 (en) * 2005-10-07 2007-06-28 Kwakernaak Martin H Interface for a-Si waveguides and III/V waveguides
US20080253728A1 (en) * 2006-09-07 2008-10-16 Massachusetts Institute Of Technology Microphotonic waveguide including core/cladding interface layer
JP2010263153A (en) * 2009-05-11 2010-11-18 Sumitomo Electric Ind Ltd Semiconductor integrated optical device, and method of making the same
WO2019225329A1 (en) * 2018-05-21 2019-11-28 日本電信電話株式会社 Optical integrated device and production method therefor

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