Electro-absorption modulated laser and method of manufacturing an electro-absorption modulated laser

Abstract

The application provides an electro-absorption modulated laser and a preparation method thereof, and relates to the technical field of electro-absorption modulated lasers. The laser comprises an epitaxial layer, a first metal bridge plate surface and a second metal bridge plate surface. The top of the epitaxial layer is provided with a ridge waveguide and an insulating second bridge pier. The ridge waveguide and the second bridge pier are arranged in a transverse direction. The first metal bridge plate surface is arranged across the ridge waveguide and the second bridge pier. The first metal bridge plate surface comprises a first part and a second part which are connected to each other. The first part covers the ridge waveguide. The second part covers the part between the ridge waveguide and the second bridge pier and covers the second bridge pier. The second metal bridge plate surface covers the top surface of the first metal bridge plate surface. The second metal bridge plate surface comprises a third part which covers the first part and a fourth part which covers the second part. The fourth part is in a mesh shape. The ridge waveguide, the second bridge pier, the first metal bridge plate surface and the second metal bridge plate surface form an air bridge structure.

Description

Technical Field

[0001] This invention relates to the field of electro-absorption modulated laser technology, and in particular to an electro-absorption modulated laser and a method for fabricating such a laser. Background Technology

[0002] Electro-absorption modulated lasers (EML lasers) are the core light source for modern high-speed optical communication. Due to their complex manufacturing process, their performance is highly dependent on process design and manufacturing capabilities, especially the electrode design that determines high-speed modulation characteristics.

[0003] Existing electroabsorption modulated lasers have an air bridge structure. When the support part under the bridge is peeled off during the fabrication of the air bridge structure, the stress release may cause the metal bridge to break, resulting in a reliability problem for the electroabsorption modulated laser. Summary of the Invention

[0004] The purpose of this invention is to provide an electroabsorption modulated laser and a method for fabricating an electroabsorption modulated laser, so as to alleviate the technical problem that the bridge surface is prone to breakage during the fabrication of the air bridge in existing lasers.

[0005] In a first aspect, the present invention provides an electro-absorption modulated laser, comprising: an epitaxial layer, a first metal bridge plate surface, and a second metal bridge plate surface;

[0006] The top of the extension is provided with a ridge waveguide and an insulated second pier, the ridge waveguide and the second pier are arranged laterally at intervals, and the first metal bridge plate surface spans between the ridge waveguide and the second pier.

[0007] The first metal bridge deck includes a first part and a second part that are interconnected; the first part covers the ridge waveguide; the second part covers the portion between the ridge waveguide and the second pier, and also covers the second pier;

[0008] The second metal bridge deck surface covers the top surface of the first metal bridge deck surface. The second metal bridge deck surface includes a third part covering the first part and a fourth part covering the second part. The fourth part is mesh-like, and the ridge waveguide, the second pier, the first metal bridge deck surface and the second metal bridge deck surface form an air bridge structure.

[0009] Furthermore, the fourth part includes a border, and the third part is connected to the border;

[0010] The frame is equipped with multiple horizontal and vertical beams arranged in a crisscross pattern, forming a mesh.

[0011] Furthermore, the top surface of the epitaxial waveguide and the transverse sidewalls of the ridge waveguide are covered with a first insulating dielectric layer;

[0012] A support portion is provided on the top surface of the first insulating dielectric layer, which is laterally spaced from the ridge waveguide;

[0013] The top surface of the first insulating dielectric layer, the top surface of the support, and the transverse sidewalls of the support are all covered with the second insulating dielectric layer.

[0014] The portion of the first insulating dielectric layer located below the support, the portion of the second insulating dielectric layer that wraps around the support, and the support form the second pier.

[0015] Furthermore, the first metal bridge deck is provided with a downward protruding first protrusion, the bottom surface of the first protrusion is in contact with the top surface of the second pier, and in the lateral direction, the downward projection of the bottom surface of the first protrusion falls within the top surface of the second pier.

[0016] The first metal bridge plate has a downwardly protruding second protrusion. The bottom surface of the second protrusion contacts the top surface of the ridge waveguide, and in the lateral direction, the projection of the ridge waveguide falls within the bottom surface of the second protrusion.

[0017] Secondly, the present invention provides a method for fabricating an electroabsorption modulated laser, comprising the following steps:

[0018] Step S1. Provide a main body, the main body including a ridge waveguide and an insulated second pier, with a lateral gap between the ridge waveguide and the second pier;

[0019] Step S2. Spin-coat the first photoresist to cover the second pier and the ridge waveguide with the first photoresist layer;

[0020] Step S3. Remove the portion of the first photoresist layer located above the ridge waveguide and the second pier;

[0021] Step S4. Prepare a first metal bridge deck surface, which spans the second pier and the ridge waveguide; the first metal bridge deck surface includes a first part and a second part that are interconnected; the first part covers the ridge waveguide; the second part covers the portion between the ridge waveguide and the second pier, and covers the second pier.

[0022] Step S5. Prepare a second metal bridge plate surface above the first metal bridge plate surface. The second metal bridge plate surface includes a third portion covering the first portion and a fourth portion covering the second portion; the fourth portion is mesh-like.

[0023] Step S6. Remove the first photoresist layer.

[0024] Furthermore, step S1 includes:

[0025] Step S11. Provide an extension;

[0026] Step S12. Fabricate a ridge waveguide on the top surface of the epitaxial layer;

[0027] Step S13. Deposit and form a first insulating dielectric layer, the first insulating dielectric layer covering the epitaxial top surface and ridge waveguide;

[0028] Step S14. A support portion is fabricated on the top surface of the first insulating dielectric layer, the support portion being laterally spaced from the ridge waveguide;

[0029] Step S15. Deposit and form a second insulating dielectric layer; the second insulating dielectric layer covers the first insulating dielectric layer, the support portion, and the ridge waveguide;

[0030] Step S16. Remove the portion of the second insulating dielectric layer located above the ridge waveguide and the portion of the first insulating dielectric layer located above the ridge waveguide to obtain the main body.

[0031] Furthermore, step S3 includes:

[0032] Step S31. Spin-coat a second photoresist onto the first photoresist layer to form a second photoresist layer. Of the materials of the first photoresist layer and the second photoresist layer, one is a positive photosensitive material and the other is a negative photosensitive material.

[0033] Step S32. A first window and a second window are formed on the second photoresist layer by exposure and development. The first window is located above the ridge waveguide, and the second window is located above the support. The length of the first window in the lateral direction is greater than the lateral length of the top surface of the ridge waveguide, and the length of the second window in the lateral direction is less than the lateral length of the top surface of the support.

[0034] Step S33. Through the first window and the second window, the portion of the first photoresist layer located above the ridge waveguide and the support is etched away, and the second photoresist layer is removed.

[0035] Furthermore, the first photoresist layer is made of benzocyclobutene.

[0036] Furthermore, step S4 specifically includes:

[0037] Step S41. In the horizontal direction, a first misaligned double-layer adhesive structure is formed on the side of the ridge waveguide facing away from the support. The first misaligned double-layer adhesive structure includes a first bottom layer adhesive (10) and a first top layer adhesive arranged vertically. The horizontal distance between the edge of the first bottom layer adhesive and the ridge waveguide is L1, and the horizontal distance between the edge of the first top layer adhesive and the ridge waveguide is L2. L1 is greater than L2.

[0038] Step S42. Evaporate the first metal material to form the first metal bridge plate surface;

[0039] Step S43. Peel off the first misaligned double-layer adhesive structure.

[0040] Furthermore, step S5 specifically includes:

[0041] Step S51. In the horizontal direction, a second staggered double-layer adhesive structure is formed on the side of the ridge waveguide facing away from the support. The second staggered double-layer adhesive structure includes a second bottom layer adhesive and a second top layer adhesive arranged vertically. The horizontal distance between the edge of the second bottom layer adhesive near the ridge waveguide and the ridge waveguide is L3, and the horizontal distance between the edge of the second top layer adhesive near the ridge waveguide and the ridge waveguide is L4. L3 is greater than L4.

[0042] A mask template with a mask image is formed on the surface of the first metal bridge plate;

[0043] Step S52. Evaporate the second metal material to form the second metal bridge plate surface, and form the fourth part through a mask.

[0044] Step S53. Peel off the second misaligned double-layer adhesive structure and the mask template.

[0045] Furthermore, step S5 specifically includes:

[0046] Step S51. In the horizontal direction, a second staggered double-layer adhesive structure is formed on the side of the ridge waveguide facing away from the support. The second staggered double-layer adhesive structure includes a second bottom layer adhesive and a second top layer adhesive arranged vertically. The horizontal distance between the edge of the second bottom layer adhesive near the ridge waveguide and the ridge waveguide is L3, and the horizontal distance between the edge of the second top layer adhesive near the ridge waveguide and the ridge waveguide is L4. L3 is greater than L4.

[0047] Step S52. Evaporate a second metal material to form a substrate;

[0048] Step S53. Etch mesh holes on the substrate to obtain the second metal bridge plate surface;

[0049] Step S54. Peel off the second misaligned double-layer adhesive structure.

[0050] Furthermore, the value range of L1 is 1 um - 1.5 um; the value range of L4 is 1 um - 1.5 um.

[0051] This invention has at least the following advantages or beneficial effects:

[0052] The electroabsorption modulated laser provided by the present invention includes: an epitaxial layer, a first metal bridge plate surface, and a second metal bridge plate surface; a ridge waveguide and an insulating second bridge pier are disposed on the top of the epitaxial layer, the ridge waveguide and the second bridge pier are arranged laterally at intervals, and the first metal bridge plate surface spans between the ridge waveguide and the second bridge pier; the first metal bridge plate surface includes a first part and a second part that are interconnected; the first part covers the ridge waveguide; the second part covers the portion between the ridge waveguide and the second bridge pier, and also covers the second bridge pier; the second metal bridge plate surface covers the top surface of the first metal bridge plate surface, and the second metal bridge plate surface includes a third part that covers the first part and a fourth part that covers the second part; the fourth part is mesh-like, and the ridge waveguide, the second bridge pier, the first metal bridge plate surface, and the second metal bridge plate surface form an air bridge structure.

[0053] The air bridge structure in this design features a double-layered deck, comprising a first metal bridge deck and a second metal bridge deck. The second metal bridge deck serves as a reinforcement, and a third section within the second metal bridge deck completely covers the first section. Below the first section is a ridge waveguide. Therefore, the superimposed first and third sections above the ridge waveguide ensure its stability. For the area between the ridge waveguide and the second pier, the fourth section on the second metal bridge deck employs a mesh design. This mesh-like fourth section has a continuous border around its perimeter and a mesh opening in the center. The continuous border reinforces the foundation, ensuring stability and eliminating the risk of metal tearing due to an excessively thin second metal bridge deck. The mesh opening reduces weight. In summary, the different patterned designs of the first and second metal bridge decks increase the stability of the air bridge, improve the reliability of the electro-absorption modulated laser, and enhance performance stability while ensuring the wire bonding of electrodes in the ridge waveguide and metal PAD areas. Attached Figure Description

[0054] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of step S2 in the method for fabricating an electroabsorption modulated laser provided in an embodiment of the present invention;

[0056] Figure 2 This is a schematic diagram of step S3 in the method for fabricating an electroabsorption modulated laser provided in an embodiment of the present invention;

[0057] Figure 3 This is a schematic diagram of step S4 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram of step S52 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0059] Figure 5 This is a schematic diagram of step S53 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0060] Figure 6 This is a schematic diagram of step S61 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0061] Figure 7 This is a schematic diagram of step S62 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0062] Figure 8 This is a schematic diagram of step S63 in the method for fabricating an electroabsorption modulated laser provided in an embodiment of the present invention;

[0063] Figure 9 This is a schematic diagram of step S71 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0064] Figure 10 This is a schematic diagram of step S72 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0065] Figure 11 This is a schematic diagram of step S73 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0066] Figure 12 This is a schematic diagram of step S8 in the method for fabricating an electro-absorption modulated laser provided in an embodiment of the present invention;

[0067] Figure 13 A top view of the first metal bridge plate in an electroabsorption modulated laser provided in an embodiment of the present invention;

[0068] Figure 14 This is a top view of the second metal bridge plate in an electroabsorption modulated laser provided in an embodiment of the present invention.

[0069] Icons: 1-Epipolar layer; 2-Ridge waveguide; 3-First insulating dielectric layer; 4-Support; 5-Second insulating dielectric layer; 6-First photoresist layer; 7-Second photoresist layer; 8-First window; 9-Second window; 10-First bottom resist; 11-First top resist; 12-First metal bridge plate surface; 13-Second bottom resist; 14-Second top resist; 15-Second metal bridge plate surface; 16-Mask; 17-First part; 18-Second part; 19-Third part; 20-Fourth part. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0071] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0072] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0073] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0074] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0075] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0076] The method for fabricating an electro-absorption modulated laser provided by this invention includes the following steps:

[0077] Step S1. Provide a main body, the main body including a ridge waveguide 2 and an insulated second pier, with a lateral gap between the ridge waveguide 2 and the second pier, wherein the lateral gap is... Figure 1 The left and right directions in the middle.

[0078] like Figure 2 As shown, two piers of the air bridge structure have been fabricated on the main body, namely the ridge waveguide 2 and the insulated second pier.

[0079] like Figure 1 As shown, step S1 specifically includes:

[0080] Step S11. Provide an extension 1.

[0081] Among them, epitaxial layer 1 is a layer structure, which specifically includes, from top to bottom, an ohmic contact layer, an upper confinement layer, a quantum well layer, a lower confinement layer, and a substrate.

[0082] Step S12. Prepare a ridge waveguide 2 on the top surface of epitaxial layer 1.

[0083] Ridge waveguide 2 can be fabricated using exposure, development, and etching processes.

[0084] Step S13. Deposit and form a first insulating dielectric layer 3, which covers the top surface of the epitaxial layer 1 and the ridge waveguide 2.

[0085] The first insulating dielectric layer 3 was deposited using a plasma-enhanced chemical vapor deposition (PECVD) device. The thickness of the first insulating dielectric layer 3 can range from 100 nm to 500 nm. The material is a silicon oxide compound with a refractive index of 1.45-1.5.

[0086] Step S14. A support portion 4 is prepared on the top surface of the first insulating dielectric layer 3, and the support portion 4 is laterally spaced from the ridge waveguide 2.

[0087] The support portion 4 can be made of photosensitive BCB, a high-grade electronic resin. The pattern of the support portion 4 can be fabricated using traditional photolithography.

[0088] Step S15. Deposit and form a second insulating dielectric layer 5; the second insulating dielectric layer 5 covers the first insulating dielectric layer 3, the support portion 4 and the ridge waveguide 2.

[0089] The same steps as in step S13 can be used to deposit and form the second insulating dielectric layer 5.

[0090] Step S16. Remove the portion of the second insulating dielectric layer 5 located above the ridge waveguide 2, and the portion of the first insulating dielectric layer 3 located above the ridge waveguide 2, to obtain the main body.

[0091] like Figure 2 As shown, in the main body, the top surface of the epitaxial layer 1 and the lateral sidewalls of the ridge waveguide 2 are covered with a first insulating dielectric layer 3. A support portion 4 is provided on the top surface of the first insulating dielectric layer 3, which is laterally spaced from the ridge waveguide 2. A second insulating dielectric layer 5 is covered on the top surface of the first insulating dielectric layer 3 (except for the part covered by the support portion 4), the top surface of the support portion 4, and the lateral sidewalls of the support portion 4.

[0092] The top surface of the ridge waveguide 2 is exposed, and the ridge waveguide 2 forms the first pier of the air bridge structure. The portion of the first insulating dielectric layer 3 located below the support portion 4, the portion of the second insulating dielectric layer 5 that encloses the support portion 4, and the support portion 4 enclosed inside the first insulating dielectric layer 3 and the second insulating dielectric layer 5 form an insulated second pier.

[0093] Photoresist is spin-coated over the second insulating dielectric layer 5 using conventional photoresist and a self-aligned process (underexposure 50%-80% + baking and reflow at 100-130℃ after development + etching) to remove the second insulating dielectric layer 5 and the first insulating dielectric layer 3 above the ridge waveguide 2. Then, a two-fluid process using IPA (isopropanol), ACE (ethyl acetate), and NMP (N-methylpyrrolidone) is used to remove the photoresist.

[0094] The fabrication method of an electroabsorption modulated laser also includes the following steps:

[0095] like Figure 3 As shown, step S2. Spin-coating the first photoresist to cover the first photoresist layer 6 over the second pier and the ridge waveguide 2.

[0096] A first photoresist is spin-coated onto the top surface of the device obtained in step S16 using a spin coater. Preferably, the first photoresist is a benzocyclobutene (BCB) photoresist.

[0097] Step S3. Remove the portion of the first photoresist layer 6 located above the ridge waveguide 2 and the second pier.

[0098] The portion of the first photoresist layer 6 located above the ridge waveguide 2 and the second pier can be removed through exposure, development, and etching processes.

[0099] like Figure 4 and Figure 5 As shown, step S3 specifically includes:

[0100] Step S31. Spin-coat a second photoresist onto the first photoresist layer 6 to form a second photoresist layer 7. Of the materials of the first photoresist layer 6 and the second photoresist layer 7, one is a positive photosensitive material and the other is a negative photosensitive material.

[0101] Ordinary photoresist AZ6130 is spin-coated onto the top surface of the first photoresist layer 6 to form the second photoresist layer 7. The material of the first photoresist layer 6 is BCB. Exposure and development of the second photoresist layer 7 does not affect the first photoresist layer 6.

[0102] like Figure 4 As shown, in step S32, a first window 8 and a second window 9 are formed on the second photoresist layer 7 by exposure and development. The first window 8 is located above the ridge waveguide 2, and the second window 9 is located above the support portion 4. The length of the first window 8 in the lateral direction is greater than the lateral length of the top surface of the ridge waveguide 2, and the length of the second window 9 in the lateral direction is less than the lateral length of the top surface of the support portion 4.

[0103] The lateral length of the first window 8 is greater than the lateral length of the top surface of the ridge waveguide 2. The first window 8 allows etching of a wide groove of the corresponding size on the first photoresist layer 6. This not only completely exposes the top surface of the ridge waveguide 2, but also provides space for the subsequent fabrication of the first metal bridge surface 12 and the second metal bridge surface 15. In the subsequent steps, the first metal bridge surface 12 and the second metal bridge surface 15 need to be formed. Taking the first metal bridge surface 12 as an example, the first metal bridge surface 12 completely covers the top surface of the ridge waveguide 2. If the first window 8 is too small, the size of the wide groove will be too small, and the edge (right side) of the wide groove will be too close to the ridge waveguide 2, or part of the top surface of the ridge waveguide 2 will not be exposed, affecting the coverage of the first metal bridge surface 12. Therefore, it is necessary to set the lateral length of the first window 8 to be greater than the lateral length of the top surface of the ridge waveguide 2, so that the top surface of the ridge waveguide 2 is completely exposed.

[0104] The second window 9 has a horizontal length that is less than the horizontal length of the top surface of the support part 4. Through the second window 9, a narrow groove of the corresponding size can be etched on the first photoresist layer 6 to provide a receiving area for the subsequent preparation of the first metal bridge plate surface 12. The first metal bridge plate surface 12 can be in stable contact with the top surface of the second pier.

[0105] like Figure 5 As shown, in step S33, the portion of the first photoresist layer 6 located above the ridge waveguide 2 and the support portion 4 is etched away through the first window 8 and the second window 9, and the second photoresist layer 7 is removed.

[0106] In step S3 above, the etching of the ridge waveguide 2 and the portion above the support 4 is performed simultaneously. In other feasible solutions, the etching of the ridge waveguide 2 and the support 4 can be performed in steps. For example, first spin-coating photoresist, then etching away the portion of the first photoresist layer 6 located above the ridge waveguide 2 through exposure, development, and etching, and then etching away the portion of the first photoresist layer 6 located above the support 4 through exposure, development, and etching.

[0107] The fabrication method of an electroabsorption modulated laser also includes the following steps:

[0108] like Figure 13 and Figure 14 As shown, step S4. Prepare a first metal bridge deck 12, which spans the second pier and the ridge waveguide 2; the first metal bridge deck 12 includes a first part 17 and a second part 18 that are connected to each other; the first part 17 covers the ridge waveguide 2; the second part 18 covers the portion between the ridge waveguide 2 and the second pier, and also covers the second pier.

[0109] The part that does not contact the first metal bridge plate surface 12 can be covered by applying adhesive, and then the first metal material can be vapor-deposited to form the first metal bridge plate surface 12. Finally, the adhesive structure is removed.

[0110] like Figure 6 As shown, step S4 specifically includes:

[0111] Step S41. In the horizontal direction, a first misaligned double-layer adhesive structure is formed on the side of the ridge waveguide 2 facing away from the support part 4. The first misaligned double-layer adhesive structure includes a first bottom layer adhesive 10 and a first top layer adhesive 11 arranged vertically. The horizontal distance L1 between the edge of the first bottom layer adhesive 10 near the ridge waveguide 2 and the ridge waveguide 2, and the horizontal distance L2 between the edge of the first top layer adhesive 11 near the ridge waveguide 2 and the ridge waveguide 2, are both greater than L2.

[0112] The first misaligned double-layer photoresist structure was prepared using a double-layer photoresist liftoff process. The first bottom layer photoresist 10 was developed at a higher rate than the first top layer photoresist 11, resulting in a length difference of ≥4µm between the first bottom layer photoresist 10 and the first top layer photoresist 11. The first bottom layer photoresist 10 had an orthogonal thickness of 0.5-1µm (the thinner the bottom photoresist, the better, to reduce metal overflow), and the first top layer photoresist 11 had a thickness of 3-3.5µm.

[0113] Specifically, it is recommended that the window size in this step be as close as possible to the top width of the ridge waveguide 2, that is, the lateral gap between the first top layer adhesive 11 and the ridge waveguide 2 should be as small as possible, so as to ensure that the right side of the first metal bridge plate surface 12 is as small as possible after the metal is deposited in the subsequent step S42, thereby reducing the influence of the electrode on the periodic rate. Since a common lithography machine is used, the gap length can be controlled at 1um-1.5um based on the actual resolution of the lithography machine.

[0114] like Figure 7 As shown, step S42 involves vapor-depositing a first metal material to form the first metal bridge surface 12. (As...) Figure 8 As shown, step S43 involves peeling off the first misaligned double-layer adhesive structure. The first metal material can be Ti, Pt, or Au.

[0115] The preparation method also includes the following steps:

[0116] Step S5. A second metal bridge plate surface 15 is prepared above the first metal bridge plate surface 12. The second metal bridge plate surface 15 includes a third portion 19 covering the first portion 17 and a fourth portion 20 covering the second portion 18; the fourth portion 20 is mesh-like.

[0117] The air bridge structure in this design features a double-layered deck, comprising a first metal bridge deck 12 and a second metal bridge deck 15. The second metal bridge deck provides reinforcement, and a third portion 19 within it completely covers the first portion 17. Below the first portion 17 is the ridge waveguide 2. Therefore, the superimposed first portion 17 and third portion 19 above the ridge waveguide 2 ensure its stability. For the section between the ridge waveguide 2 and the second pier, a fourth portion 20 on the second metal bridge deck 15 employs a mesh design. This mesh-like fourth portion 20 has continuous borders around its perimeter and perforations in the center. The continuous borders reinforce the foundation, ensuring stability and eliminating the risk of metal tearing due to the thinness of the second metal bridge deck 15. The perforations also reduce weight. In summary, the different patterned designs of the first metal bridge deck 12 and the second metal bridge deck 15 enhance the stability of the air bridge while ensuring the proper wire bonding of electrodes in the ridge waveguide 2 area and the metal PAD area.

[0118] Step S5 specifically includes:

[0119] like Figure 9 As shown, in step S51, a second staggered double-layer adhesive structure is formed on the side of the ridge waveguide 2 facing away from the support portion 4 in the lateral direction. The second staggered double-layer adhesive structure includes a second bottom adhesive 13 and a second top adhesive 14 disposed vertically. The lateral distance L3 between the edge of the second bottom adhesive 13 near the ridge waveguide 2 and the ridge waveguide 2 is equal to the lateral distance L4 between the edge of the second top adhesive 14 near the ridge waveguide 2 and the ridge waveguide 2 is equal to the lateral distance L4. L3 is greater than L4. A mask template 16 with a mask image is formed on the first metal bridge plate surface 12.

[0120] The operation process of step S51 is roughly the same as that of step S41. After step S43, the second misaligned double-layer adhesive structure is prepared by double-layer adhesive liftoff process, and double-layer positive adhesive is spin-coated. The development rate of the second bottom adhesive 13 is higher than that of the second top adhesive 14, and the length difference between the second bottom adhesive 13 and the second top adhesive 14 is ≥4um. The orthogonal thickness of the second bottom adhesive 13 is 1-1.5um (the thinner the bottom photoresist, the better, to reduce metal overflow). The thickness of the second top adhesive 14 is 3-3.5um.

[0121] Specifically, it is recommended that the window size in this step be as close as possible to the top width of the ridge waveguide 2, that is, the lateral gap between the second top layer adhesive 14 and the ridge waveguide 2 should be as small as possible, so as to ensure that the right side of the second metal bridge plate surface 15 after metal evaporation and forming in the subsequent step S52 is as small as possible, thereby reducing the influence of the electrode on the periodic rate. Since a common lithography machine is used, the gap length can be controlled at 1um-1.5um based on the actual resolution of the lithography machine.

[0122] like Figure 13 and Figure 14 As shown, after the second misaligned double-layer adhesive structure is prepared, a mask template 16 with a mask image is formed on the surface 12 of the first metal bridge plate. The image of the mask template 16 is designed to realize the patterns of the third part 19 and the fourth part 20 in step S52.

[0123] like Figure 10 As shown, in step S52, a second metal material is vapor-deposited to form a second metal bridge plate surface 15, and a fourth part 20 is formed through a mask 16.

[0124] like Figure 11 As shown, step S53. Peel off the second misaligned double-layer adhesive structure and the mask template 16.

[0125] The material of the second metal raw material is Ti / Pt / Au.

[0126] like Figure 4 and Figure 12As shown, and due to the special window opening method (first window and second window) in step S3, the first metal bridge plate surface 12 has a downward protruding first protrusion, the bottom surface of the first protrusion is in contact with the top surface of the second pier, and in the lateral direction, the downward projection of the bottom surface of the first protrusion falls within the top surface of the second pier; the first metal bridge plate surface 12 is provided with a downward protruding second protrusion, the bottom surface of the second protrusion is in contact with the top surface of the ridge waveguide 2, and in the lateral direction, the upward projection of the ridge waveguide 2 falls within the bottom surface of the second protrusion. The lateral length of the first window 8 is greater than the lateral length of the top surface of the ridge waveguide 2. A wide groove of the corresponding size can be etched on the first photoresist layer 6 through the first window 8 to form the second protrusion, which can completely expose the top surface of the ridge waveguide 2. The first metal bridge plate surface 12 completely covers the top surface of the ridge waveguide 2. If the first window 8 is too small, the size of the wide groove will be too small, the edge (right side) of the wide groove will be too close to the ridge waveguide 2, or part of the top surface of the ridge waveguide 2 will not be exposed, affecting the coverage of the first metal bridge plate surface 12. Therefore, it is necessary to set the lateral length of the first window 8 to be greater than the lateral length of the top surface of the ridge waveguide 2 so that the top surface of the ridge waveguide 2 is completely exposed. The second window 9 has a lateral length less than the lateral length of the top surface of the support portion 4. Through the second window 9, a narrow groove of corresponding size can be etched into the first photoresist layer 6. Subsequently, a first protrusion can be formed within the narrow groove, providing a accommodating area for the fabrication of the first metal bridge plate surface 12. The first metal bridge plate surface 12 can then stably contact the top surface of the second pier. Therefore, step S3, in conjunction with steps S4 and S5, can achieve sufficient contact between the first metal bridge plate surface 12 and the top surface of the ridge waveguide 2.

[0127] like Figure 12 As shown, step S6. Remove the first photoresist layer 6.

[0128] The bottom BCB filler was removed by soaking and heating with BCB-specific adhesive remover at 85°C, thus completing the air bridge structure.

[0129] Example 2

[0130] Unlike the method of preparing the second metal bridge plate surface 15 in Example 1, in this example, step S5 specifically includes:

[0131] Step S51. In the horizontal direction, a second staggered double-layer adhesive structure is formed on the side of the ridge waveguide 2 facing away from the support part 4. The second staggered double-layer adhesive structure includes a second bottom adhesive 13 and a second top adhesive 14 arranged vertically. The horizontal distance L3 between the edge of the second bottom adhesive 13 near the ridge waveguide 2 and the ridge waveguide 2 is L3. The horizontal distance L4 between the edge of the second top adhesive 14 near the ridge waveguide 2 and the ridge waveguide 2 is L4. L3 is greater than L4.

[0132] This step only forms the second misaligned double-layer adhesive structure, without setting the mask template 16.

[0133] Step S52. Evaporate a second metal material to form a substrate.

[0134] Step S53. Etch mesh holes on the substrate to obtain the second metal bridge plate surface 15.

[0135] The third part 19 and the fourth part 20 are etched on the complete metal bridge plate surface as required by etching, thereby obtaining the second metal bridge plate surface 15.

[0136] Step S54. Peel off the second misaligned double-layer adhesive structure.

[0137] like Figures 12-14 As shown, the electroabsorption modulated laser provided in this embodiment can be formed in the manner described above.

[0138] The electroabsorption modulated laser provided by the present invention includes: an epitaxial layer 1, a first metal bridge plate surface 12, and a second metal bridge plate surface 15; a ridge waveguide 2 and an insulated second bridge pier are disposed on the top of the epitaxial layer 1, the ridge waveguide 2 and the second bridge pier are arranged laterally at intervals, and the first metal bridge plate surface 12 spans between the ridge waveguide 2 and the second bridge pier; the first metal bridge plate surface 12 includes a first portion 17 and a second portion 18 that are interconnected; the first portion 17 covers the ridge waveguide 2; the second portion 18 covers the portion between the ridge waveguide 2 and the second bridge pier, and also covers the second bridge pier; the second metal bridge plate surface 15 covers the top surface of the first metal bridge plate surface 12, and the second metal bridge plate surface 15 includes a third portion 19 that covers the first portion 17 and a fourth portion 20 that covers the second portion 18; the fourth portion 20 is mesh-like, and the ridge waveguide 2, the second bridge pier, the first metal bridge plate surface 12, and the second metal bridge plate surface 15 form an air bridge structure.

[0139] The air bridge structure in this design features a double-layered deck, comprising a first metal bridge deck 12 and a second metal bridge deck 15. The second metal bridge deck provides reinforcement, and a third portion 19 within it completely covers the first portion 17. Below the first portion 17 is the ridge waveguide 2. Therefore, the superimposed first portion 17 and third portion 19 above the ridge waveguide 2 ensure its stability. For the section between the ridge waveguide 2 and the second pier, a fourth portion 20 on the second metal bridge deck 15 employs a mesh design. This mesh-like fourth portion 20 has continuous borders around its perimeter and perforations in the center. The continuous borders reinforce the foundation, ensuring stability and eliminating the risk of metal tearing due to the thinness of the second metal bridge deck 15. The perforations also reduce weight. In summary, the different patterned designs of the first metal bridge deck 12 and the second metal bridge deck 15 enhance the stability of the air bridge while ensuring the proper wire bonding of electrodes in the ridge waveguide 2 area and the metal PAD area.

[0140] like Figure 14 As shown, the fourth part 20 includes a frame, and the third part 19 is connected to the frame; multiple horizontal beams and multiple vertical beams are arranged in a crisscross pattern inside the frame, and the multiple horizontal beams and multiple vertical beams form a mesh.

[0141] The crossbeams and longitudinal beams also reinforce the frame when forming the mesh, ensuring the stability of the second metal bridge deck 15 even with the openings.

[0142] like Figure 12 As shown, the top surface of the extension 1 and the lateral sidewall of the ridge waveguide 2 are covered with a first insulating dielectric layer 3; a support portion 4 is provided on the top surface of the first insulating dielectric layer 3, which is laterally spaced from the ridge waveguide 2; a second insulating dielectric layer 5 is covered on the top surface of the first insulating dielectric layer 3, the top surface of the support portion 4, and the lateral sidewall of the support portion 4; the portion of the first insulating dielectric layer 3 located below the support portion 4, the portion of the second insulating dielectric layer 5 that wraps around the support portion 4, and the support portion 4 form the second pier.

[0143] The support portion 4 is wrapped by the first insulating dielectric layer 3 and the second insulating dielectric layer 5, thereby forming an insulating second bridge pier. After the first insulating dielectric layer 3, the support portion 4 and the second insulating dielectric layer 5 are prepared in sequence, the support portion 4 is wrapped. Then, the first insulating dielectric layer 3 and the second insulating dielectric layer 5 on the top surface of the ridge waveguide 2 are removed, exposing the top surface of the ridge waveguide 2.

[0144] like Figure 12 As shown, the first metal bridge deck surface 12 is provided with a downwardly protruding first protrusion, the bottom surface of the first protrusion is in contact with the top surface of the second bridge pier, and in the lateral direction, the downward projection of the bottom surface of the first protrusion falls within the top surface of the second bridge pier; the first metal bridge deck surface 12 is provided with a downwardly protruding second protrusion, the bottom surface of the second protrusion is in contact with the top surface of the ridge waveguide 2, and in the lateral direction, the upward projection of the ridge waveguide 2 falls within the bottom surface of the second protrusion.

[0145] like Figure 12 As shown, the top surface of the second pier has a larger area, which can fully support the first protrusion and achieve a stable support function. The bottom surface of the second protrusion has a larger area than the top surface of the ridge waveguide 2, which can achieve full contact between the first metal bridge plate 12 and the ridge waveguide 2 and achieve a stable electrical connection.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electroabsorption modulated laser, characterized in that, include: Extension (1), first metal bridge plate surface (12), and second metal bridge plate surface (15); The top of the extension (1) is provided with a ridge waveguide (2) and an insulated second pier. The ridge waveguide (2) and the second pier are arranged laterally at intervals. The first metal bridge plate surface (12) spans between the ridge waveguide (2) and the second pier. The first metal bridge deck (12) includes a first part (17) and a second part (18) that are connected to each other; the first part (17) covers the ridge waveguide (2); the second part (18) covers the portion between the ridge waveguide (2) and the second pier, and covers the second pier; The second metal bridge deck surface (15) covers the top surface of the first metal bridge deck surface (12). The second metal bridge deck surface (15) includes a third part (19) covering the first part (17) and a fourth part (20) covering the second part (18). The fourth part (20) is mesh-like. The ridge waveguide (2), the second pier, the first metal bridge deck surface (12) and the second metal bridge deck surface (15) form an air bridge structure.

2. The electroabsorption modulated laser according to claim 1, characterized in that, The fourth part (20) includes a border, and the third part (19) is connected to the border; The frame is provided with multiple horizontal beams and multiple vertical beams arranged in a crisscross pattern, and the multiple horizontal beams and multiple vertical beams form a mesh.

3. The electroabsorption modulated laser according to claim 1, characterized in that, The top surface of the epitaxial layer (1) and the transverse sidewalls of the ridge waveguide (2) are covered with a first insulating dielectric layer (3). A support portion (4) is provided on the top surface of the first insulating dielectric layer (3) and is laterally spaced from the ridge waveguide (2). The top surface of the first insulating dielectric layer (3), the top surface of the support part (4), and the transverse sidewall of the support part (4) are all covered with a second insulating dielectric layer (5). The portion of the first insulating dielectric layer (3) located below the support portion (4), the portion of the second insulating dielectric layer (5) that wraps around the support portion (4), and the support portion (4) form the second pier.

4. The electroabsorption modulated laser according to claim 1, characterized in that, The first metal bridge deck (12) is provided with a downward protruding first protrusion. The bottom surface of the first protrusion contacts the top surface of the second bridge pier, and in the horizontal direction, the downward projection of the bottom surface of the first protrusion falls within the top surface of the second bridge pier. The first metal bridge plate surface (12) is provided with a downward protruding second protrusion. The bottom surface of the second protrusion contacts the top surface of the ridge waveguide (2), and in the lateral direction, the upward projection of the ridge waveguide (2) falls within the bottom surface of the second protrusion.

5. A method for fabricating an electroabsorption modulated laser, characterized in that, Including the following steps: Step S1. Provide a main body, the main body including a ridge waveguide (2) and an insulated second pier, there being a lateral gap between the ridge waveguide (2) and the second pier; Step S2. Spin-coat the first photoresist to cover the first photoresist layer (6) over the second pier and ridge waveguide (2); Step S3. Remove the portion of the first photoresist layer (6) located above the ridge waveguide (2) and the second pier; Step S4. Prepare a first metal bridge deck surface (12) that spans the second pier and the ridge waveguide (2); the first metal bridge deck surface (12) includes a first part (17) and a second part (18) that are connected to each other; the first part (17) covers the ridge waveguide (2); the second part (18) covers the portion between the ridge waveguide (2) and the second pier, and covers the second pier; Step S5. A second metal bridge plate surface (15) is prepared above the first metal bridge plate surface, the second metal bridge plate surface (15) including a third portion (19) covering the first portion (17) and a fourth portion (20) covering the second portion (18); the fourth portion (20) is mesh-like; Step S6. Remove the first photoresist layer (6).

6. The method for fabricating an electroabsorption modulated laser according to claim 5, characterized in that, Step S1 includes: Step S11. Provide an extension (1); Step S12. Prepare a ridge waveguide (2) on the top surface of the epitaxial layer (1); Step S13. Deposit and form a first insulating dielectric layer (3) that covers the top surface of the epitaxial layer (1) and the ridge waveguide (2). Step S14. A support portion (4) is prepared on the top surface of the first insulating dielectric layer (3), the support portion (4) being laterally spaced from the ridge waveguide (2); Step S15. Deposit and form a second insulating dielectric layer (5); the second insulating dielectric layer (5) covers the first insulating dielectric layer (3), the support (4) and the ridge waveguide (2); Step S16. Remove the portion of the second insulating dielectric layer (5) located above the ridge waveguide (2) and the portion of the first insulating dielectric layer (3) located above the ridge waveguide (2) to obtain the main body.

7. The method for fabricating an electroabsorption modulated laser according to claim 6, characterized in that, Step S3 includes: Step S31. Spin coat the second photoresist onto the first photoresist layer (6) to form the second photoresist layer (7). The material of the first photoresist layer (6) and the material of the second photoresist layer (7) are, respectively, a positive photosensitive material and a negative photosensitive material. Step S32. A first window (8) and a second window (9) are formed on the second photoresist layer (7) by exposure and development. The first window (8) is located above the ridge waveguide (2), and the second window (9) is located above the support (4). The first window (8) is longer in the lateral direction than the lateral length of the top surface of the ridge waveguide (2), and the second window (9) is shorter in the lateral direction than the lateral length of the top surface of the support (4). Step S33. Through the first window (8) and the second window (9), the portion of the first photoresist layer (6) located above the ridge waveguide (2) and the support (4) is etched away, and the second photoresist layer (7) is removed.

8. The method for fabricating an electroabsorption modulated laser according to claim 7, characterized in that, The first photoresist layer (6) is made of benzocyclobutene.

9. The method for fabricating an electroabsorption modulated laser according to claim 6, characterized in that, Step S4 specifically includes: Step S41. In the lateral direction, a first misaligned double-layer adhesive structure is formed on the side of the ridge waveguide (2) facing away from the support (4). The first misaligned double-layer adhesive structure includes a first bottom layer adhesive (10) and a first top layer adhesive (11) arranged vertically. The lateral distance L1 between the edge of the first bottom layer adhesive (10) near the ridge waveguide (2) and the ridge waveguide (2) is L1, and the lateral distance L2 between the edge of the first top layer adhesive (11) near the ridge waveguide (2) and the ridge waveguide (2) is L2. L1 is greater than L2. Step S42. Evaporate the first metal material to form the first metal bridge plate surface (12); Step S43. Peel off the first misaligned double-layer adhesive structure.

10. The method for fabricating an electroabsorption modulated laser according to claim 9, characterized in that, Step S5 specifically includes: Step S51. In the lateral direction, a second staggered double-layer adhesive structure is formed on the side of the ridge waveguide (2) facing away from the support (4). The second staggered double-layer adhesive structure includes a second bottom adhesive (13) and a second top adhesive (14) arranged vertically. The lateral distance L3 between the edge of the second bottom adhesive (13) near the ridge waveguide (2) and the ridge waveguide (2) is L3. The lateral distance L4 between the edge of the second top adhesive (14) near the ridge waveguide (2) and the ridge waveguide (2) is L4. L3 is greater than L4. A mask template (16) with a mask image is formed on the first metal bridge plate surface (12); Step S52. A second metal material is vapor deposited to form a second metal bridge plate surface (15), and a fourth part (20) is formed through the mask (16). Step S53. Peel off the second misaligned double-layer adhesive structure and the mask template (16).

11. The method for fabricating an electroabsorption modulated laser according to claim 9, characterized in that, Step S5 specifically includes: Step S51. In the lateral direction, a second staggered double-layer adhesive structure is formed on the side of the ridge waveguide (2) facing away from the support (4). The second staggered double-layer adhesive structure includes a second bottom adhesive (13) and a second top adhesive (14) arranged vertically. The lateral distance L3 between the edge of the second bottom adhesive (13) near the ridge waveguide (2) and the ridge waveguide (2) is L3. The lateral distance L4 between the edge of the second top adhesive (14) near the ridge waveguide (2) and the ridge waveguide (2) is L4. L3 is greater than L4. Step S52. Evaporate a second metal material to form a substrate; Step S53. Etch mesh holes on the substrate to obtain the second metal bridge plate surface (15); Step S54. Peel off the second misaligned double-layer adhesive structure.

12. The method for fabricating an electroabsorption modulated laser according to claim 10 or 11, characterized in that, The value range of L1 is 1 μm - 1.5 μm; the value range of L4 is 1 μm - 1.5 μm.

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