CN112180501A - Silicon-based optical coupling structure, silicon-based monolithic integrated optical device and manufacturing method thereof - Google Patents

Silicon-based optical coupling structure, silicon-based monolithic integrated optical device and manufacturing method thereof Download PDF

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CN112180501A
CN112180501A CN201910600341.5A CN201910600341A CN112180501A CN 112180501 A CN112180501 A CN 112180501A CN 201910600341 A CN201910600341 A CN 201910600341A CN 112180501 A CN112180501 A CN 112180501A
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silicon
optical waveguide
waveguide structure
substrate
optical
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汪巍
方青
涂芝娟
曾友宏
蔡艳
余明斌
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Shanghai Industrial Utechnology Research Institute
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Shanghai Industrial Utechnology Research Institute
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Priority to CN201910600341.5A priority Critical patent/CN112180501A/en
Priority to PCT/CN2019/096424 priority patent/WO2021000350A1/en
Publication of CN112180501A publication Critical patent/CN112180501A/en
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12Light 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
    • G02B6/12002Three-dimensional structures
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12Light 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
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12Light 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
    • G02B6/12004Combinations of two or more optical elements
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/10Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/12Light 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
    • G02B6/13Integrated optical circuits characterised by the manufacturing method
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/42Coupling light guides with opto-electronic elements
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/42Coupling light guides with opto-electronic elements
    • G02B6/4201Packages, e.g. shape, construction, internal or external details
    • G02B6/4204Packages, e.g. shape, construction, internal or external details the coupling comprising intermediate optical elements, e.g. lenses, holograms
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24Coupling light guides
    • G02B6/42Coupling light guides with opto-electronic elements
    • G02B6/4296Coupling light guides with opto-electronic elements coupling with sources of high radiant energy, e.g. high power lasers, high temperature light sources

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Optical Integrated Circuits (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

The application provides a silicon-based optical coupling structure, a silicon-based monolithic integrated optical device and a manufacturing method thereof. The silicon-based optical coupling structure includes: a first groove portion formed in a substrate silicon of a silicon-on-insulator (SOI) substrate; a first optical waveguide structure formed in top silicon of the silicon-on-insulator (SOI) substrate; a second optical waveguide structure connected to the first optical waveguide structure in a lateral direction, extending in a first direction in the lateral direction, and located above the first groove portion; and through grooves formed on both sides of the second optical waveguide structure in a second direction in the lateral direction, the second direction being perpendicular to the first direction, the through grooves communicating with the first groove portions, wherein a refractive index of a material of the second optical waveguide structure is lower than a refractive index of a material of the first optical waveguide structure. The coupling efficiency of the light field can be improved.

Description

Silicon-based optical coupling structure, silicon-based monolithic integrated optical device and manufacturing method thereof
Technical Field
The present disclosure relates to the field of semiconductor technologies, and in particular, to a silicon-based optical coupling structure and a method for manufacturing the same, and a silicon-based monolithic integrated optical device and a method for manufacturing the same.
Background
The silicon photon practical application faces a great technical problem in light sources, and silicon is an indirect band gap material, so that the light emitting efficiency is low, the band edge absorption coefficient is low, and a silicon light emitting device is difficult to realize.
The method of introducing light of an external light source into a chip by using a coupler and adopting a III-V group hybrid integrated laser are the most mainstream methods of introducing the light source at present.
In addition to the above methods, an all-silicon raman laser researched by Intel (Intel) and a silicon germanium and III-V quantum dot monolithic integrated laser researched by the american college of labor and technology of massachusetts and the american university of california have made a series of breakthroughs in recent years, the performance of the lasers gradually meets practical requirements, and technical reserves are provided for realizing silicon-based optical interconnection compatible with a complete CMOS process in the future.
It should be noted that the above background description is only for the convenience of clear and complete description of the technical solutions of the present application and for the understanding of those skilled in the art. Such solutions are not considered to be known to the person skilled in the art merely because they have been set forth in the background section of the present application.
Disclosure of Invention
The silicon-based monolithic integrated laser needs to epitaxially grow germanium, III-V and other direct band gap materials on silicon or silicon-on-insulator, and due to the difference between the material system and the material height, the realization of the high-efficiency optical field coupling of the laser and a silicon optical chip has a great challenge, and is one of the important challenges facing the practical application of the current silicon-based monolithic integrated laser.
The embodiment of the application provides a silicon-based optical coupling structure and a manufacturing method thereof, and a silicon-based monolithic integrated optical device and a manufacturing method thereof.
According to an aspect of an embodiment of the present application, there is provided a silicon-based optical coupling structure, comprising:
a first groove portion formed in a substrate silicon of a silicon-on-insulator (SOI) substrate;
a first optical waveguide structure formed in top silicon of the silicon-on-insulator (SOI) substrate;
a second optical waveguide structure connected to the first optical waveguide structure in a lateral direction, extending in a first direction in the lateral direction, and located above the first groove portion; and
and through grooves formed on both sides of the second optical waveguide structure in a second direction perpendicular to the first direction, the through grooves communicating with the first groove portions, wherein a refractive index of a material of the second optical waveguide structure is lower than a refractive index of a material of the first optical waveguide structure.
According to another aspect of an embodiment of the present application, wherein the silicon-based optical coupling structure further comprises:
and a support structure formed in the through groove, having the same size as the through groove in a second direction, and supporting the second optical waveguide structure from the second direction.
According to another aspect of the embodiments of the present application, wherein the second optical waveguide structure has:
a rectangular waveguide which is rectangular in a lateral direction and extends in the first direction;
and a tapered waveguide which is tapered in a lateral direction, extends in the first direction, and has a different width at both ends in the first direction, wherein the rectangular waveguide is connected to a wider end of the tapered waveguide in the first direction.
According to another aspect of the embodiments herein, wherein the material of the second optical waveguide structure is silicon oxide.
According to another aspect of the embodiments of the present application, the first optical waveguide structure has a reverse tapered structure on a side near the second optical waveguide structure.
According to another aspect of an embodiment of the present application, wherein,
at least a portion of the first optical waveguide structure is located over the first groove portion.
According to another aspect of the embodiments of the present application, there is provided a silicon-based monolithically integrated optical device having:
a silicon-based optical coupling structure as described in any of the above aspects; and
a laser formed on a bottom surface of a second groove portion of a substrate silicon of the silicon-on-insulator (SOI) substrate, and/or a silicon photonic chip formed in the top silicon of the silicon-on-insulator (SOI) substrate,
wherein the content of the first and second substances,
the light emitting layer of the laser is longitudinally in the same position as the first optical waveguide structure and laterally towards the second optical waveguide structure,
the light receiving part of the silicon optical chip faces the first optical waveguide structure in the transverse direction, and the light receiving part is covered by the outer cladding layer.
According to another aspect of an embodiment of the present application, there is provided a method of fabricating a silicon-based optical coupling structure, comprising:
forming a first optical waveguide structure in top silicon of a silicon-on-insulator (SOI) substrate and forming an outer cladding layer covering the first optical waveguide structure in longitudinal and lateral directions;
etching substrate silicon from the over cladding layer to the silicon-on-insulator substrate to form a second optical waveguide structure laterally connected to the first optical waveguide structure, the second optical waveguide structure extending in a lateral first direction and having through-grooves formed on both sides of the second optical waveguide structure in a lateral second direction; and
etching the substrate silicon under the second optical waveguide structure and at least part of the first optical waveguide structure through the through-trenches to form a first recess portion in the substrate silicon,
wherein the refractive index of the material of the second optical waveguide structure is lower than the refractive index of the material of the first optical waveguide structure.
According to another aspect of the embodiments of the present application, wherein etching the substrate silicon through the through trench to form a first groove portion includes:
and etching the substrate silicon by using an isotropic etching method to suspend the second optical waveguide structure and at least part of the first optical waveguide structure.
According to another aspect of the embodiments of the present application, there is provided a method for manufacturing a silicon-based monolithically integrated optical device, the method comprising:
forming a first optical waveguide structure in top silicon of a silicon-on-insulator (SOI) substrate and forming an outer cladding layer covering the first optical waveguide structure in longitudinal and lateral directions;
defining a groove area in a silicon-on-insulator (SOI) substrate, and etching the groove area until the substrate silicon below the groove area is etched by a preset thickness to form a second groove part;
forming a laser on a bottom surface of the second groove portion, a light emitting layer of the laser being at the same position in a longitudinal direction as the first optical waveguide structure;
etching from the outer cladding layer between the laser and the first optical waveguide structure to the substrate silicon of the silicon-on-insulator substrate to form a second optical waveguide structure connected laterally between the first optical waveguide structure and the laser, the second optical waveguide structure extending in a lateral first direction and having through-trenches formed on both sides of the second optical waveguide structure in a lateral second direction; and
etching the substrate silicon under the second optical waveguide structure and at least part of the first optical waveguide structure through the through-trenches to form a first recess portion in the substrate silicon,
wherein the refractive index of the material of the second optical waveguide structure is lower than the refractive index of the material of the first optical waveguide structure.
The beneficial effect of this application lies in: the silicon-based optical coupling structure has a suspended structure, and therefore high-efficiency coupling of an optical field can be achieved.
Specific embodiments of the present application are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the application may be employed. It should be understood that the embodiments of the present application are not so limited in scope. The embodiments of the application include many variations, modifications and equivalents within the spirit and scope of the appended claims.
Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.
It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the application, are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 is a schematic cross-sectional view of a silicon-based monolithically integrated optical device having a silicon-based optical coupling structure of example 1 of the present application;
FIG. 2a is a perspective view of a silicon-based optical coupling structure according to example 1 of the present application;
FIG. 2b is a plan view of the first optical waveguide structure and the second optical waveguide structure in embodiment 1 of the present application;
FIG. 3 is a schematic diagram of a method of fabricating a silicon-based optical coupling structure according to example 2 of the present application;
fig. 4 is a schematic diagram of a method for manufacturing a silicon-based monolithically integrated optical device according to embodiment 2 of the present application.
Detailed Description
The foregoing and other features of the present application will become apparent from the following description, taken in conjunction with the accompanying drawings. In the description and drawings, particular embodiments of the application are disclosed in detail as being indicative of some of the embodiments in which the principles of the application may be employed, it being understood that the application is not limited to the described embodiments, but, on the contrary, is intended to cover all modifications, variations, and equivalents falling within the scope of the appended claims.
In the description of the embodiments of the present application, for convenience of description, a direction parallel to the surface of the substrate is referred to as "lateral direction", and a direction perpendicular to the surface of the substrate is referred to as "longitudinal direction", wherein "thickness" of each component means a dimension of the component in the "longitudinal direction", a direction pointing from the substrate silicon of the substrate to the top layer silicon in the "longitudinal direction" is referred to as "upper" direction, and a direction opposite to the "upper" direction is referred to as "lower" direction.
Example 1
The embodiment of the application provides a silicon-based optical coupling structure.
Fig. 1 is a schematic cross-sectional view of a silicon-based monolithically integrated optical device having a silicon-based optical coupling structure of the present embodiment, and fig. 2a is a schematic perspective view of a silicon-based optical coupling structure.
As shown in FIGS. 1 and 2a, a silicon-based optical coupling structure 1 includes: first groove portion 11, first optical waveguide structure 12, second optical waveguide structure 13, and through groove 14 (not shown in fig. 1, shown in fig. 2 a).
In the present embodiment, the first groove portion 11 is formed in the substrate silicon 101 of the silicon-on-insulator (SOI) substrate 10.
In the present embodiment, as shown in fig. 1 and 2a, the first optical waveguide structure 12 is formed in the top silicon 102 of the silicon-on-insulator (SOI) substrate 10, and at least a portion of the first optical waveguide structure 12 may be located above the first groove portion 11.
In the present embodiment, as shown in fig. 1 and 2a, the second optical waveguide structure 13 is connected to the first optical waveguide structure 12 in the lateral direction, and the second optical waveguide structure 13 extends in the first direction L1 in the lateral direction, and the second optical waveguide structure 13 is located above the first groove portion 11. Furthermore, as shown in fig. 2a, the second optical waveguide structure 13 may also surround a portion of the first optical waveguide structure 12 in a transverse second direction L2, wherein the second direction L2 is perpendicular to the first direction L1.
In the present embodiment, as shown in fig. 2a, through grooves 14 may be formed on both sides of the second optical waveguide structure 13 in the transverse second direction L2, and the through grooves 14 communicate with the first groove portions 11.
According to the present embodiment, the first optical waveguide structure 12 and the second optical waveguide structure 13 can be formed as a suspended structure, so as to avoid light leakage from the substrate and improve the efficiency of optical field coupling; further, the through grooves 14 are formed on both sides of the second optical waveguide structure 13, and light can be prevented from leaking from the side surfaces of the second optical waveguide structure 13.
In the present embodiment, the refractive index of the material of the second optical waveguide structure 13 may be lower than the refractive index of the material of the first optical waveguide structure 12, whereby light can be efficiently coupled from the second optical waveguide structure 13 into the first optical waveguide structure 12 in a portion where the second optical waveguide structure 13 surrounds the first optical waveguide structure 12 from the second direction. In the present embodiment, the first optical waveguide structure 12 is formed by using the top silicon 102 of the SOI substrate 10, and the material thereof is silicon; while the second optical waveguide structure 13 may be formed by the buried oxide layer 103 of the SOI substrate 10 and the outer cladding layer 15 covering the first optical waveguide structure 12, the material of the second optical waveguide structure 13 may be silicon oxide, such as silicon dioxide (SiO)2)。
In this embodiment, an outer cladding layer 15 may cover the first optical waveguide structure 12 in both the lateral and longitudinal directions, as shown in FIG. 1. Further, the lower side of the first optical waveguide structure 12 may be covered by the buried oxide layer 103 of the SOI substrate 10. Thereby, the first optical waveguide structure 12 is surrounded by the material of lower refractive index in the entire circumference around the first direction L1, reducing leakage of light from the first optical waveguide structure 12.
In this embodiment, as shown in fig. 2a, the silicon-based optical coupling structure 1 may further have a support structure 16, and the support structure 16 is formed in the through trench 14 and has the same size as the through trench 14 in the second direction L2. The support structure 16 is fixedly connected between the walls of the through groove 14 in the second direction L2, and thus the second optical waveguide structure 13 can be supported from the second direction L2, and the structural stability of the second optical waveguide structure 13 can be improved.
In the present embodiment, as shown in fig. 2a, the second optical waveguide structure 13 has: a first rectangular waveguide 131 and a tapered waveguide 132. Wherein the first rectangular waveguide 131 is rectangular in the lateral direction, extending in the first direction L1; the tapered waveguide 132 is tapered in the lateral direction, extends in the first direction L1, and has different widths at both ends in the first direction, wherein the wider end 132a of the tapered waveguide 132 is connected to the first rectangular waveguide 131 in the first direction L1. In addition, the second optical waveguide structure 13 has a second rectangular waveguide 133 having a narrow width, and the second rectangular waveguide 133 is connected to the narrow end of the tapered waveguide 132.
Fig. 2b is a schematic plan view of the first optical waveguide structure 12 and the second optical waveguide structure 13 in a plane parallel to the surface of the substrate 10 in embodiment 1 of the present application.
In the present embodiment, as shown in fig. 2b, the first optical waveguide structure 12 has a reverse tapered structure 121 in the L1 direction, wherein the reverse tapered structure 121 is located at a side of the first optical waveguide structure 12 close to the second optical waveguide structure 13 in the L1 direction.
As shown in fig. 2b, the reverse tapered structure 121 may be encased in the second optical waveguide structure 13 in the lateral direction, for example, the reverse tapered structure 121 may be encased in the tapered waveguide 132 and the second rectangular waveguide 133. Wherein, the width of the inverse tapered structure 121 in the second direction L2 may be: the width of the reverse tapered structure 121 is narrowest at an end toward the first rectangular waveguide 131, and gradually increases as it goes farther from the first rectangular waveguide 131 along the direction L1.
When light enters the silicon waveguide from the SiO2 waveguide, the mode field of the SiO2 waveguide is greatly different from that of the silicon waveguide, and the coupling loss is increased. In the present application, since the first optical waveguide structure 12 has the reverse tapered structure 121, the reverse tapered structure 121 can increase the mode field in the first optical waveguide structure 12, so that when light enters the first optical waveguide structure 12 from the second optical waveguide structure 13, mode field matching can be achieved, and coupling loss can be reduced.
Furthermore, in the present embodiment, as shown in fig. 2b, the first optical waveguide structure 12 may further have a rectangular structure 122 in the L1 direction, wherein the rectangular structure 122 is further away from one side of the first rectangular waveguide 131 than the reverse tapered structure 121 in the L1 direction.
Further, in the present embodiment, the thickness of the first optical waveguide structure 12 may remain the same or different throughout the L1 direction.
As shown in fig. 1, the silicon-based monolithically integrated optical device 100 may have: a silicon-based optical coupling structure 1, a laser 2, and a silicon optical chip 3.
As shown in fig. 1, the laser 2 may be formed on the surface of the second groove portion 17 of the substrate silicon 101 of the silicon-on-insulator (SOI) substrate 10, and the silicon photonic chip 3 may be formed in the top layer silicon 102 of the silicon-on-insulator (SOI) substrate 10.
In the present embodiment, the laser 2 may be, for example, an edge emitting laser, wherein the laser 2 may be fabricated by direct bandgap material stack such as epitaxial III-V, Ge (Sn). The light emitting layer 21 of the laser 2 is at the same height as the first optical waveguide structure 12, i.e. the light emitting layer 21 of the laser 2 is at the same position in the longitudinal direction as the first optical waveguide structure 12. Further, the light emitting layer 21 of the laser 2 is laterally directed towards the second optical waveguide structure 13, and the light emitting layer 21 may be laterally covered by the outer cladding layer 15, whereby light emitted by the light emitting layer 21 may be coupled into the second optical waveguide structure 13 via the outer cladding layer 15.
In this embodiment, a light receiving portion (not shown) of the silicon photo chip 3 may be directed toward the first optical waveguide structure 12 in a lateral direction, and an upper surface of the light receiving portion may be covered with an outer cladding layer 15. Thereby, light coupled into the first optical waveguide structure 12 can be coupled into the silicon photonics chip 3.
As shown in fig. 1, in the present embodiment, light emitted from the light emitting layer 21 of the laser 2 is coupled to the second optical waveguide structure 13, and is transmitted to the first optical waveguide structure 12, and is further introduced into the silicon photonic chip 3. It can be seen that although the thickness of the laser 2 is thick, in the present application, the laser 2 is formed on the surface of the second groove portion 17 of the substrate silicon 101 of the SOI substrate 10, so that the laser 2 can be a sunken laser, and can be aligned with the first optical waveguide structure 12 in the longitudinal direction, and therefore, the height difference between the light emitting layer 21 of the laser 2 and the silicon optical chip 3 can be effectively reduced, and the coupling difficulty can be reduced.
It should be noted that, in fig. 1, the silicon-based monolithic integrated optical device 100 has both the laser 2 and the silicon optical chip 3, but the present embodiment is not limited to this, and for example, the silicon-based monolithic integrated optical device 100 may have only one of the laser 2 and the silicon optical chip 3 in addition to the silicon-based optical coupling structure 1. In addition, in the present embodiment, the laser 2 and the silicon microchip 3 are merely examples, and the present embodiment may not be limited thereto, and for example, the laser 2 and the silicon microchip 3 may be other optical devices.
Example 2
Embodiment 2 provides a method of fabricating a silicon-based optical coupling structure for fabricating the silicon-based optical coupling structure described in embodiment 1.
FIG. 3 is a schematic diagram of a method for fabricating a silicon-based optical coupling structure according to the present embodiment, as shown in FIG. 3, in the present embodiment, the method may include:
step 301, forming a first optical waveguide structure 12 in a top silicon 102 of a silicon-on-insulator (SOI) substrate 10, for example, by photolithography and etching to form the first optical waveguide structure 12; and, forming an outer cladding layer 15 covering the first optical waveguide structure in longitudinal and lateral directions, for example, depositing SiO2 material to form the outer cladding layer 15;
step 302, etching the substrate silicon 101 of the silicon-on-insulator substrate 10 from the outer cladding layer 15 to form a second optical waveguide structure 13 laterally connected to the first optical waveguide structure 12, the second optical waveguide structure 13 extending in the first lateral direction, and through grooves 14 formed on both sides of the second optical waveguide structure 13 in the second lateral direction, the surface of the substrate silicon 101 being exposed to the through grooves 14, for example, etching downward from the outer cladding layer 15 by using photolithography and etching processes to form the through grooves 14 until the substrate silicon 101 is exposed, and stopping the etching; and
step 303, etching the second optical waveguide structure 13 and at least part of the substrate silicon 101 below the first optical waveguide structure 12 through the through trench 14 to form a first groove portion 11 in the substrate silicon 10.
In the present embodiment, the refractive index of the material of the second optical waveguide structure 13 is lower than the refractive index of the material of the first optical waveguide structure 12.
In this embodiment, step 303 may include the following steps:
step 3031, the substrate silicon 101 is etched using an isotropic etch process to leave the second optical waveguide structure 13 and at least a portion of the first optical waveguide structure 12 suspended.
The isotropic etching method in step 3031 is, for example, isotropic dry etching, and sulfur hexafluoride (SF6) may be used as an etching gas.
In addition, in this embodiment, step 303 may further include, after step 3031, the following steps:
step 3032, continuing to etch the substrate silicon 101 by using an anisotropic etching method to increase the depth of the first groove portion 11.
The anisotropic etching method in step 3032 is, for example, anisotropic dry etching, and a mixed gas of sulfur hexafluoride (SF6) and octafluorocyclobutane (C4F8) may be used as an etching gas. Further, the step 3032 Dekker depth may be, for example, 100 microns.
In this embodiment, the method for fabricating the silicon-based optical coupling structure shown in fig. 3 may be included in the method for fabricating the silicon-based monolithically integrated optical device 100 described in embodiment 1.
Fig. 4 is a schematic diagram of a method for manufacturing the silicon-based monolithically integrated optical device of the present embodiment. As shown in fig. 4, in the present embodiment, the manufacturing method may include:
step 401 of forming a first optical waveguide structure 12 in top silicon 102 of a silicon-on-insulator (SOI) substrate 10 and forming an outer cladding layer 15 covering the first optical waveguide structure 12 in longitudinal and lateral directions, the step 401 being as described above with reference to step 301;
step 402, defining a trench region in a silicon-on-insulator (SOI) substrate 10, and etching the trench region until the substrate silicon below the trench region is etched by a predetermined thickness, for example, 2 microns, to form a second groove portion 17;
step 403, forming a laser 2 on the bottom surface of the second groove portion 17, wherein a light emitting layer 21 of the laser 2 and the first optical waveguide structure 12 are in the same position in the longitudinal direction, for example, epitaxial stacking of III-V materials and active region materials such as ge (sn) on silicon on the bottom surface of the second groove portion 17, and preparing the laser 2;
step 404, etching down the substrate silicon 101 of the silicon-on-insulator substrate 10 from the outer cladding layer 15 between the laser 2 and the first optical waveguide structure 12 to form a second optical waveguide structure 13 connected laterally between the first optical waveguide structure 12 and the laser 2, the second optical waveguide structure 13 extending in a first lateral direction, and through grooves 14 formed on both sides of the second optical waveguide structure 13 in a second lateral direction, wherein reference is made to step 302 for a specific implementation of step 404; and
step 405, etching the substrate silicon 101 under the second optical waveguide structure 13 and at least part of the first optical waveguide structure 12 through the through-trench 14 to form the first recess portion 11 in the substrate silicon 101, a specific embodiment of step 404 may refer to step 303.
In the embodiment of fig. 4, the refractive index of the material of the second optical waveguide structure 13 is lower than the refractive index of the material of the first optical waveguide structure 12.
In addition, in this embodiment, after the laser 2 is formed in step 403, an outer cladding layer 15 may be additionally deposited so as to cover the laser in the outer cladding layer 15, and the outer cladding layer 15 is filled between the laser 3 and the first optical waveguide structure 12, so as to form the second optical waveguide structure 13 in step 404.
In addition, in the present embodiment, before the first optical waveguide structure 12 is formed, the silicon optical chip 3 may be formed, and the silicon optical chip may be covered with the outer cladding layer 15.
According to the present embodiment, the first optical waveguide structure 12 and the second optical waveguide structure 13 can be formed as a suspended structure, so that light leakage from the substrate is avoided, and the efficiency of optical field coupling is improved; further, the through grooves 14 are formed on both sides of the second optical waveguide structure 13, so that light can be prevented from leaking from the side surfaces of the second optical waveguide structure 13; in addition, the laser 2 is formed on the surface of the second groove part 17 of the substrate silicon 101 of the SOI substrate 10, so that the laser 2 can be a sinking laser, and can be aligned with the first optical waveguide structure 12 in the longitudinal direction, the height difference between the light emitting layer 21 of the laser 2 and the silicon optical chip 3 can be effectively reduced, and the coupling difficulty can be reduced.
The present application has been described in conjunction with specific embodiments, but it should be understood by those skilled in the art that these descriptions are intended to be illustrative, and not limiting. Various modifications and adaptations of the present application may occur to those skilled in the art based on the spirit and principles of the application and are within the scope of the application.

Claims (10)

1. A silicon-based optical coupling structure, comprising:
a first groove portion formed in a substrate silicon of a silicon-on-insulator (SOI) substrate;
a first optical waveguide structure formed in top silicon of the silicon-on-insulator (SOI) substrate;
a second optical waveguide structure connected to the first optical waveguide structure in a lateral direction, extending in a first direction in the lateral direction, and located above the first groove portion; and
through grooves formed on both sides of the second optical waveguide structure in a second direction in a lateral direction, the second direction being perpendicular to the first direction, the through grooves communicating with the first groove portions,
wherein the refractive index of the material of the second optical waveguide structure is lower than the refractive index of the material of the first optical waveguide structure.
2. A silicon-based optical coupling structure as defined in claim 1 wherein the silicon-based optical coupling structure further comprises:
and a support structure formed in the through groove, having the same size as the through groove in a second direction, and supporting the second optical waveguide structure from the second direction.
3. A silicon-based optical coupling structure according to claim 1 wherein the second optical waveguide structure has:
a rectangular waveguide which is rectangular in a lateral direction and extends in the first direction;
and a tapered waveguide which is tapered in a lateral direction, extends in the first direction, and has a different width at both ends in the first direction, wherein the rectangular waveguide is connected to a wider end of the tapered waveguide in the first direction.
4. A silicon-based optical coupling structure according to claim 1,
the material of the second optical waveguide structure is silicon oxide.
5. A silicon-based optical coupling structure according to claim 1,
the first optical waveguide structure has a reverse tapered structure on a side adjacent to the second optical waveguide structure.
6. A silicon-based optical coupling structure according to claim 1,
at least a portion of the first optical waveguide structure is located over the first groove portion.
7. A silicon-based monolithically integrated optical device, comprising:
a silicon-based optical coupling structure according to any of claims 1 to 6; and
a laser formed on a bottom surface of a second groove portion of a substrate silicon of the silicon-on-insulator (SOI) substrate, and/or a silicon photonic chip formed in the top silicon of the silicon-on-insulator (SOI) substrate,
wherein the content of the first and second substances,
the light emitting layer of the laser is longitudinally in the same position as the first optical waveguide structure and laterally towards the second optical waveguide structure,
the light receiving part of the silicon optical chip faces the first optical waveguide structure in the transverse direction, and the light receiving part is covered by the outer cladding layer.
8. A method of fabricating a silicon-based optical coupling structure, comprising:
forming a first optical waveguide structure in top silicon of a silicon-on-insulator (SOI) substrate and forming an outer cladding layer covering the first optical waveguide structure in longitudinal and lateral directions;
etching substrate silicon from the over cladding layer to the silicon-on-insulator substrate to form a second optical waveguide structure laterally connected to the first optical waveguide structure, the second optical waveguide structure extending in a lateral first direction and having through-grooves formed on both sides of the second optical waveguide structure in a lateral second direction; and
etching the substrate silicon under the second optical waveguide structure and at least part of the first optical waveguide structure through the through-trenches to form a first recess portion in the substrate silicon,
wherein the refractive index of the material of the second optical waveguide structure is lower than the refractive index of the material of the first optical waveguide structure.
9. A method of fabricating a silicon-based optical coupling structure as defined in claim 8 wherein etching the substrate silicon through the through trench to form a first recess portion comprises:
and etching the substrate silicon by using an isotropic etching method to suspend the second optical waveguide structure and at least part of the first optical waveguide structure.
10. A method of fabricating a silicon-based monolithically integrated optical device, the method comprising:
forming a first optical waveguide structure in top silicon of a silicon-on-insulator (SOI) substrate and forming an outer cladding layer covering the first optical waveguide structure in longitudinal and lateral directions;
defining a groove area in a silicon-on-insulator (SOI) substrate, and etching the groove area until the substrate silicon below the groove area is etched by a preset thickness to form a second groove part;
forming a laser on a bottom surface of the second groove portion, a light emitting layer of the laser being at the same position in a longitudinal direction as the first optical waveguide structure;
etching from the outer cladding layer between the laser and the first optical waveguide structure to the substrate silicon of the silicon-on-insulator substrate to form a second optical waveguide structure connected laterally between the first optical waveguide structure and the laser, the second optical waveguide structure extending in a lateral first direction and having through-trenches formed on both sides of the second optical waveguide structure in a lateral second direction; and
etching the substrate silicon under the second optical waveguide structure and at least part of the first optical waveguide structure through the through-trenches to form a first recess portion in the substrate silicon,
wherein the refractive index of the material of the second optical waveguide structure is lower than the refractive index of the material of the first optical waveguide structure.
CN201910600341.5A 2019-07-04 2019-07-04 Silicon-based optical coupling structure, silicon-based monolithic integrated optical device and manufacturing method thereof Pending CN112180501A (en)

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