A heterogeneously integrated modulator device
By incorporating an air slot into the optoelectronic device, the problems of high microwave loss in metal electrodes and poor optical velocity matching were solved, achieving the effects of reducing waveguide loss and increasing modulator bandwidth.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- 国科光芯金杏(北京)实验室科技有限公司
- Filing Date
- 2025-09-22
- Publication Date
- 2026-06-26
Smart Images
Figure CN224417138U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of semiconductor technology, specifically to a heterogeneous integrated modulation device. Background Technology
[0002] In conventional optoelectronic devices (such as heterogeneous integrated modulators like traveling-wave electrode lithium niobate modulators), material and structural limitations result in high microwave losses in metal electrodes and poor matching between microwave and optical velocities, thus limiting the modulator's bandwidth. Furthermore, metal ions in conventional metal electrodes (such as copper electrodes) diffuse within the SiO2 cladding. Typically, a tantalum / tantalum nitride (Ta / TaN) barrier layer is deposited at the bottom of the Cu electrode, and a silicon nitride (SiN) or Ta / TaN barrier layer is deposited on the upper surface of the Cu electrode. However, these barrier layers (SiN or Ta / TaN) absorb the optical field between the waveguide core and the heterogeneous bonding layer, increasing waveguide losses. Moreover, due to overlay misalignment, the width of the barrier layer on the upper surface is usually greater than the width of the Cu electrode, causing the barrier layer to extend towards the waveguide, further increasing waveguide losses.
[0003] Therefore, a solution is needed to reduce the microwave loss of metal electrodes, improve the matching degree between microwave speed and optical speed, thereby increasing the bandwidth of the modulator, while minimizing the absorption of the optical field by the electrodes and / or blocking layers, and reducing waveguide loss. Utility Model Content
[0004] In view of this, the present invention provides a heterogeneous integrated modulation device to solve the problems in related technologies, such as the large microwave loss of metal electrodes, poor matching degree between microwave speed and optical speed, which limits the bandwidth of the modulator, and the absorption of the light field by the blocking layer used for metal electrodes and their surface, which leads to increased waveguide loss.
[0005] In a first aspect, this utility model provides a heterogeneous integrated modulation device, comprising:
[0006] The substrate, cladding, and heterobonding layer are stacked from bottom to top;
[0007] At least one waveguide core is embedded inside the cladding and located below the heterobonded layer;
[0008] Multiple electrodes are embedded inside the cladding and located on both sides of each waveguide core along its length.
[0009] Multiple air slots are located between the waveguide core and adjacent electrodes, and the depth of the air slots is at least greater than the maximum depth of the waveguide core.
[0010] The heterogeneous integrated modulation device provided by this invention utilizes an air groove between the waveguide core and the electrodes. Firstly, due to the low refractive index of air, the air groove prevents light field leakage into the electrodes, thus avoiding absorption and reducing waveguide loss. Secondly, the low dielectric constant of air improves the matching degree between the microwave velocity and the optical velocity of the electrodes, and the low absorption coefficient of air reduces microwave loss, effectively increasing the modulator's bandwidth. Furthermore, the depth of the air groove is at least greater than the maximum depth of the waveguide core, further reducing absorption and microwave loss. Therefore, the heterogeneous integrated modulation device provided by this invention reduces waveguide loss, increases bandwidth, and ultimately improves modulation performance, meeting the requirements of low loss and high bandwidth in high-speed communication scenarios.
[0011] In one alternative implementation, the plane containing the highest point of the air slot is the upper surface of the cladding; the heterogeneous bonding layer covers the upper opening of the air slot.
[0012] In one alternative implementation, the projection of the waveguide core onto the substrate overlaps with the projection of the heterobonded layer onto the substrate; the length of the air groove is greater than the length of the overlapping portion and less than or equal to the length of the electrode.
[0013] The heterogeneous integrated modulation device provided by this utility model has an air slot whose highest point is located on the upper surface of the cladding. The heterogeneous bonding layer covers the upper opening of the air slot. The length of the air slot is greater than the length of the overlapping part and less than or equal to the length of the electrode, so that the air slot can completely block the entire overlapping part, further preventing the optical field between the waveguide core and the heterogeneous bonding layer from leaking into the electrode and / or the blocking layer, avoiding the absorption of the optical field by the electrode and / or the blocking layer, thereby reducing the waveguide loss. At the same time, the large projected area of the air slot can further improve the matching degree between the microwave velocity and the optical velocity of the electrode, reduce the microwave loss of the electrode, thereby increasing the bandwidth of the modulator, and thus more effectively improving the modulation performance of the heterogeneous integrated modulator.
[0014] In one alternative implementation, the width of the air trough is greater than or equal to 0.5 μm;
[0015] The distance between the air slot and the adjacent waveguide core is greater than the distance between the air slot and the adjacent electrode.
[0016] The heterogeneous integrated modulation device provided by this invention has an air slot width greater than or equal to 0.5 μm, which can effectively reduce waveguide loss while ensuring processing accuracy. The distance between the air slot and the adjacent waveguide core is greater than the distance between the air slot and the adjacent electrode, which can optimize the optical field distribution, reduce the absorption of the optical field by the electrode, increase the microwave propagation speed, effectively improve the matching degree between the microwave speed and the optical wave speed of the electrode, and effectively reduce the microwave loss of the electrode, thereby effectively increasing the bandwidth of the modulator.
[0017] In one alternative implementation, the width of the waveguide core is 0.8 μm to 1.5 μm;
[0018] The width of the electrode is 10μm to 150μm;
[0019] The distance between the waveguide core and the adjacent electrode is 2μm to 4μm;
[0020] The width of the air trough is 0.5μm to 2μm.
[0021] The heterogeneous integrated modulation device provided by this invention, through the aforementioned specific dimensional design, features a waveguide core width of 0.8μm to 1.5μm, meeting the requirements for optical signal mode transmission while facilitating fabrication. The electrode width is 10μm to 150μm, ensuring that the characteristic impedance and microwave loss of the electrodes meet requirements. The distance between the waveguide core and adjacent electrodes is 2μm to 4μm, meeting modulation efficiency requirements. The air slot width is 0.5μm to 2μm, meeting manufacturing requirements, effectively reducing waveguide loss and electrode microwave loss, improving photoelectric speed matching, and increasing bandwidth.
[0022] In one optional embodiment, a first barrier layer and a second barrier layer are further disposed inside the cladding layer;
[0023] The first barrier layer covers the sides and bottom of each electrode;
[0024] A second barrier layer covers the upper surface of each electrode;
[0025] The width of the second barrier layer is greater than the width of the electrode.
[0026] The heterogeneous integrated modulation device provided by this invention, by setting a first barrier layer on the side and bottom of the electrode and a second barrier layer on the upper surface of the electrode, can suppress the diffusion of metal ions in the electrode and avoid contamination of the waveguide layer. At the same time, since the air slot is located between the first barrier layer and the waveguide core, and between the second barrier layer and the waveguide core, it can effectively prevent excessive absorption of the optical field by the electrode and the barrier layer, thereby reducing waveguide loss.
[0027] In one optional implementation, the first barrier layer is a Ta / TaN barrier layer;
[0028] The second barrier layer is either a Ta / TaN barrier layer or a SiN barrier layer.
[0029] In one alternative implementation, the substrate layer is made of silicon;
[0030] The waveguide core is made of silicon nitride;
[0031] The electrode material is copper;
[0032] The cladding material is silicon dioxide;
[0033] The material of the heterobonding layer is lithium niobate.
[0034] In one alternative implementation, the maximum depth of the electrode is greater than the maximum depth of the waveguide core;
[0035] The depth of the air groove is greater than or equal to the maximum depth of the electrode;
[0036] The top surface of the waveguide core is flush with the top surface of the electrode;
[0037] The projection of the electrode on the vertical plane covers the projection of the waveguide core on the vertical plane.
[0038] In one alternative implementation, the height of the waveguide core is 200 nm to 400 nm;
[0039] The height of the electrode is 0.8 μm to 1.5 μm;
[0040] The depth of the air trough is 0.5μm to 1.5μm.
[0041] The heterogeneous integrated modulation device provided by this invention, through the aforementioned specific dimensional design, achieves a waveguide core height of 200nm–400nm, meeting the requirements for optical signal transmission while facilitating fabrication. The electrode height is 0.8μm–1.5μm, ensuring that characteristic impedance, microwave transmission speed, and microwave loss meet requirements. The air slot depth is 0.5μm–1.5μm, further enhancing the waveguide loss reduction effect. Attached Figure Description
[0042] To more clearly illustrate the technical solutions in the specific embodiments or related technologies of this utility model, the drawings used in the description of the specific embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0043] Figure 1 This is a schematic diagram of the structure of a heterogeneous integrated modulation device according to an embodiment of the present invention.
[0044] Figure 2 This is a top view schematic diagram of the structure of a heterogeneous integrated modulation device according to an embodiment of the present utility model.
[0045] Figure 3 This is a schematic diagram of the structure of the second blocking layer in a heterogeneous integrated modulation device according to an embodiment of the present invention.
[0046] Figure 4 This is a schematic diagram of the structure of the second blocking layer in another heterogeneous integrated modulation device according to an embodiment of the present invention.
[0047] Figure 5 This is a graph showing the relationship between the width of the air trough and the waveguide loss in Experiment 1 according to an embodiment of this utility model.
[0048] Figure 6 This is an amplitude-frequency response curve of a heterogeneous integrated modulation device with different air slot widths in Experiment 2 of the present invention.
[0049] Figure 7 This is an amplitude-frequency response curve of a heterogeneous integrated modulation device with different air slot depths in Experiment 3 of this utility model embodiment.
[0050] Figure 8 This is a schematic flowchart of another method for fabricating a heterogeneous integrated modulation device according to an embodiment of the present invention.
[0051] Figure 9 This is a schematic diagram of another heterogeneous integrated modulation device according to an embodiment of the present invention.
[0052] Figure label:
[0053] 10. Substrate; 20. Cladding; 21. First cladding; 22. Second cladding; 23. Third cladding; 30. Heterogeneous bonding layer; 40. Waveguide core; 50. Electrode; 61. First barrier layer; 62. Second barrier layer; 70. Air groove; 80. Upper cladding; 100. Optical field. Detailed Implementation
[0054] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, not the entire structure.
[0055] With the rapid development of optoelectronic devices, improving modulator performance is crucial for meeting the demands of high-speed communication. In conventional optoelectronic devices (such as heterogeneous integrated modulators like traveling-wave electrode lithium niobate modulators), material and structural limitations result in high microwave losses in metal electrodes and poor matching between microwave and optical velocities, thus limiting the modulator's bandwidth. Furthermore, metal ions in conventional metal electrodes (such as copper electrodes) diffuse within the SiO2 cladding. Typically, a tantalum / tantalum nitride (Ta / TaN) barrier layer is deposited at the bottom of the Cu electrode, and silicon nitride (SiN) or Ta / TaN is deposited on the upper surface of the Cu electrode as a barrier layer to prevent metal ion diffusion. However, the electrodes and their surface barrier layers absorb the optical field between the waveguide core and the heterogeneous bonding layer, leading to increased waveguide losses.
[0056] In existing technologies, the copper processing employs a damascus process. After forming electrode trenches through photolithography etching, a barrier layer is deposited first, followed by copper electroplating and chemical mechanical polishing, and finally, silicon nitride is deposited as the upper barrier layer. Due to overlay misalignment, the barrier layer width is typically larger than the copper electrode width, causing the barrier layer to extend towards the waveguide, further increasing waveguide loss and exacerbating the waveguide loss problem. Therefore, optimizing the structural design to reduce loss and improve speed matching has become a pressing technical challenge.
[0057] Therefore, a solution is needed to reduce the microwave loss of metal electrodes, improve the matching degree between microwave speed and optical speed, thereby increasing the bandwidth of the modulator, while minimizing the absorption of the optical field by the electrodes and / or blocking layers, and reducing waveguide loss.
[0058] like Figure 1 As shown, this embodiment provides a heterogeneous integrated modulation device, including:
[0059] The substrate layer 10, cladding layer 20 and heterobonding layer 30 are stacked from bottom to top;
[0060] At least one waveguide core 40 is embedded inside the cladding 20 and located below the heterobonding layer 30;
[0061] Multiple electrodes 50 are embedded inside the cladding 20 and located on both sides of each waveguide core 40 in the longitudinal direction;
[0062] Multiple air slots 70, each air slot 70 is located between the waveguide core 40 and the adjacent electrode 50, and the depth of the air slot 70 is at least greater than the maximum depth of the waveguide core 40.
[0063] In specific implementation, the depth of the air groove 70 is at least greater than the maximum depth of the waveguide core 40, that is, the depth of the air groove 70 is at least greater than the depth of a portion of the electrodes 50. Specifically, the depth of the air groove 70 being at least greater than the maximum depth of the waveguide core 40 means that the plane containing the lowest point of the air groove 70 is lower than the lower surface of the waveguide core 40.
[0064] In some embodiments, the maximum depth of electrode 50 is greater than the maximum depth of waveguide core 40, meaning the lower surface of electrode 50 is lower than the lower surface of waveguide core 40. Preferably, the depth of air groove 70 is at least greater than the maximum depth of electrode 50, meaning the plane containing the lowest point of air groove 70 is lower than the lower surface of electrode 50. Optionally, a barrier layer is provided on the surface of electrode 50.
[0065] Specifically, the waveguide core 40 is located below the heterobonded layer 30, and the silicon oxide cladding between the waveguide core 40 and the heterobonded layer 30 is relatively thin, together forming an optical waveguide as the main transmission path for optical signals. During the operation of the modulation device, the optical field 100 between the waveguide core 40 and the heterobonded layer 30 is modulated by an electric field.
[0066] In related technologies, the electrodes on both sides of the waveguide core absorb the optical field to a certain extent. In this application, the air groove can isolate the waveguide core and the electrodes, that is, isolate the electrodes from the optical field.
[0067] The heterogeneous integrated modulation device provided by this invention utilizes an air groove between the waveguide core and the electrode. Firstly, due to the low refractive index of air, the air groove prevents the light field from leaking into the electrode, effectively limiting the light field and preventing absorption by the electrode, thereby reducing waveguide loss. Secondly, because of the low dielectric constant of air, the air groove improves the matching degree between the microwave velocity and the optical velocity of the electrode, thus increasing the electro-optic bandwidth. Furthermore, the low absorption coefficient of air reduces the microwave loss of the electrode, effectively increasing the modulator's bandwidth. Therefore, the heterogeneous integrated modulation device provided by this invention can reduce waveguide loss and increase the bandwidth of the heterogeneous integrated modulation device, meeting the requirements of low loss and high bandwidth in high-speed communication scenarios.
[0068] In some alternative embodiments, the depth of the air groove 70 is greater than or equal to the maximum depth of the electrode 50. This means that the plane containing the lowest point of the air groove 70 is not higher than the lower surface of the electrode 50.
[0069] Preferably, the depth of the air groove 70 is greater than the maximum depth of the electrode 50, that is, the plane where the lowest point of the air groove 70 is located is lower than the lower surface of the electrode 50. This can further improve the matching degree between the microwave speed and the optical speed of the electrode, reduce the microwave loss of the electrode, thereby increasing the electro-optic bandwidth, and at the same time further reduce the absorption of the light field by the electrode.
[0070] In practice, within the limits allowed by the device structure, the greater the depth of the air slot 70, the better, as it can effectively improve the bandwidth of the modulator.
[0071] In some alternative embodiments, the plane containing the highest point of the air groove 70 is the upper surface of the cladding 20; the heterogeneous bonding layer 30 covers the upper opening of the air groove 70.
[0072] In some alternative implementations, such as Figure 2 As shown, the projection of the waveguide core on the substrate layer overlaps with the projection of the heterobonded layer on the substrate layer; the length of the air groove is greater than the length of the overlapping part, and less than or equal to the length of the electrode.
[0073] Specifically, the length of the air trough is between the length of the overlapping portion and the length of the electrode, which can effectively isolate the electrode and the light field.
[0074] The heterogeneous integrated modulation device provided by this utility model has an air slot whose highest point is located on the upper surface of the cladding. The heterogeneous bonding layer covers the upper opening of the air slot. The length of the air slot is greater than the length of the overlapping part and less than or equal to the length of the electrode, so that the air slot can completely block the entire overlapping part, further preventing the optical field between the waveguide core and the heterogeneous bonding layer from leaking into the electrode and / or the blocking layer, avoiding the absorption of the optical field by the electrode and / or the blocking layer, thereby reducing the waveguide loss. At the same time, the large projected area of the air slot can further improve the matching degree between the microwave velocity and the optical velocity of the electrode, reduce the microwave loss of the electrode, thereby increasing the bandwidth of the modulator, and thus more effectively improving the modulation performance of the heterogeneous integrated modulator.
[0075] Specifically, the length of electrode 50 refers to the distance that electrode 50 extends along the length of waveguide core 40; the length of air slot 70 refers to the distance that air slot 70 extends along the length of waveguide core 40.
[0076] In some alternative implementations, electrode 50 is a traveling wave electrode.
[0077] In some alternative implementations, the upper surface of electrode 50 is flush with the upper surface of waveguide core 40, or the upper surface of electrode 50 is higher than the upper surface of waveguide core 40.
[0078] In some alternative implementations, the width of the air slot 70 is greater than or equal to 0.5 μm;
[0079] The distance between the air slot 70 and the adjacent waveguide core 40 is greater than the distance between the air slot 70 and the adjacent electrode 50.
[0080] Specifically, since the air slot 70 is relatively closer to the electrode 50, it can effectively reduce the absorption of the light field 100 by the electrode 50. At the same time, the distance between the air slot 70 and the adjacent waveguide core 40 is relatively large, which can more effectively limit the distribution area of the light field 100, thereby more effectively reducing waveguide loss and electrode loss, and improving microwave propagation speed, which is beneficial to increasing bandwidth.
[0081] The heterogeneous integrated modulation device provided by this invention has an air slot width greater than or equal to 0.5 μm, which can effectively reduce waveguide loss while ensuring processing accuracy. The distance between the air slot and the adjacent waveguide core is greater than the distance between the air slot and the adjacent electrode, which can optimize the optical field distribution, reduce the absorption of the optical field by the electrode, and more effectively improve the matching degree between the microwave velocity and the optical wave velocity of the electrode. It can also more effectively reduce the microwave loss of the electrode and increase the microwave propagation speed, thereby effectively increasing the bandwidth of the modulator.
[0082] Specifically, waveguide loss can be further reduced by adjusting the width of the air slot 70.
[0083] In some alternative implementations, the depth of the air groove 70 is less than the thickness of the cladding 20, meaning that the air groove 70 does not completely penetrate the cladding 20, which can improve the reliability of the device and the sealing performance of the air groove 70.
[0084] In some alternative embodiments, the width of the air groove 70 is 0.5 μm to 2.0 μm, and the depth of the air groove 70 is 0.5 μm to 1.5 μm.
[0085] Specifically, by adjusting the width and depth of the air slot 70, the microwave loss of the electrode 50 can be further reduced, thereby effectively increasing the bandwidth of the modulator and further improving the overall performance of the device.
[0086] In some alternative implementations, the width of the waveguide core 40 is 0.8 μm to 1.5 μm;
[0087] The width of electrode 50 is 10μm to 150μm;
[0088] The distance between the waveguide core 40 and the adjacent electrode 50 is 2μm to 4μm;
[0089] The width of the air trough 70 is 0.5μm to 2μm.
[0090] In specific implementation, electrode 50 can be a signal electrode or a ground electrode; the width of the signal electrode is 10μm to 40μm, and the width of the ground electrode is 100μm to 150μm.
[0091] The heterogeneous integrated modulation device provided by this invention, through the aforementioned specific dimensional design, features a waveguide core width of 0.8μm to 1.5μm, meeting the requirements for optical signal mode transmission while facilitating fabrication. The electrode width is 10μm to 150μm, ensuring that the characteristic impedance and microwave loss of the electrodes meet requirements. The distance between the waveguide core and adjacent electrodes is 2μm to 4μm, satisfying modulation efficiency requirements. The air slot width is 0.5μm to 2μm, meeting manufacturing requirements, effectively reducing waveguide and electrode microwave losses, improving photoelectric speed matching, and increasing bandwidth.
[0092] In some alternative embodiments, electrode 50 is a metal electrode 50; the material of electrode 50 includes copper.
[0093] In some alternative embodiments, the barrier layer includes a first barrier layer 61 and a second barrier layer 62.
[0094] In some optional embodiments, a first barrier layer 61 and a second barrier layer 62 are further provided inside the cladding 20;
[0095] The first barrier layer 61 covers the sides and bottom of each electrode 50;
[0096] The second barrier layer 62 covers the upper surface of each electrode 50.
[0097] Specifically, the first barrier layer 61 and the second barrier layer 62 constitute the barrier layer.
[0098] The heterogeneous integrated modulation device provided by this invention suppresses the diffusion of metal ions in the electrodes and avoids contamination of the waveguide layer by setting a first barrier layer on the side and bottom surfaces of the electrodes and a second barrier layer on the top surface of the electrodes. Simultaneously, since the air slots are located between the first barrier layer and the waveguide core, and between the second barrier layer and the waveguide core, excessive absorption of the optical field by the electrodes and barrier layers can be effectively avoided, reducing waveguide loss.
[0099] In some alternative implementations, the width of the second barrier layer 62 is greater than the width of the electrode 50.
[0100] In some alternative implementations, the distance between the air slot 70 and the adjacent waveguide core 40 is greater than the distance between the air slot 70 and the adjacent second blocking layer 62, which can effectively reduce the absorption of the optical field 100 by the second blocking layer 62 and reduce waveguide loss. Furthermore, it can more effectively improve the matching degree between the microwave velocity and the optical velocity of the electrode 50, and more effectively reduce the microwave loss of the electrode 50, thereby effectively increasing the bandwidth of the modulator.
[0101] In some alternative embodiments, the first barrier layer 61 is a Ta / TaN barrier layer;
[0102] The second barrier layer 62 is a Ta / TaN barrier layer or a SiN barrier layer.
[0103] Specifically, in some examples, such as Figure 3 As shown, the second barrier layer 62 is a Ta / TaN barrier layer; in other examples, such as Figure 4 As shown, the second barrier layer 62 is a SiN barrier layer, for example, the second barrier layer 62 can be a Si3N4 barrier layer.
[0104] In some alternative implementations, the depth of the air groove 70 is at least greater than the maximum depth of the first barrier layer 61 at the bottom of the electrode 50, so that the air groove 70 can completely block the electrode 50 and the first barrier layer 61.
[0105] In some alternative embodiments, the projection of the air groove 70 on the vertical plane at least covers the projection of the electrode 50 on the vertical plane, and covers the projections of the first blocking layer 61 and the second blocking layer 62 on the vertical plane, so that the air groove 70 can completely block the electrode 50, the first blocking layer 61 and the second blocking layer 62.
[0106] In some alternative embodiments, the heterogeneous integrated modulation device further includes an upper cladding layer 80 covering the upper surface of the heterobonding layer 30; the upper cladding layer 80 is made of silicon dioxide.
[0107] In some alternative embodiments, the cross-sectional shape of the air trough 70 is rectangular.
[0108] In some alternative embodiments, the substrate 10 is made of silicon; the waveguide core 40 is made of silicon nitride.
[0109] The electrode 50 is made of copper; the cladding 20 is made of silicon dioxide.
[0110] The material of the heterobonding layer 30 is lithium niobate.
[0111] Specifically, the waveguide core 40 is made of silicon nitride because it has low optical loss and high refractive index, which can effectively improve the transmission efficiency of optical signals. The electrode 50 is made of copper because it has excellent conductivity and low resistivity, which can effectively reduce microwave loss.
[0112] In some alternative implementations, the maximum depth of electrode 50 is greater than the maximum depth of waveguide core 40; the depth of air groove 70 is greater than or equal to the maximum depth of electrode 50.
[0113] In some alternative implementations, the top surface of the waveguide core 40 is flush with the top surface of the electrode 50;
[0114] The projection of electrode 50 on the vertical plane covers the projection of waveguide core 40 on the vertical plane.
[0115] In some alternative implementations, the height of the waveguide core 40 is 200 nm to 400 nm;
[0116] The height of electrode 50 is 0.8 μm to 1.5 μm;
[0117] The depth of the air trough 70 is 0.5μm to 1.5μm.
[0118] The heterogeneous integrated modulation device provided by this invention, through the aforementioned specific dimensional design, achieves a waveguide core height of 200nm–400nm, meeting the requirements for optical signal transmission while facilitating fabrication. The electrode height is 0.8μm–1.5μm, ensuring that characteristic impedance, microwave transmission speed, and microwave loss meet requirements. The air slot depth is 0.5μm–1.5μm, further enhancing the waveguide loss reduction effect.
[0119] To verify the relationship between the width of the air slot and the waveguide loss, Experiment 1 was conducted. Keeping other conditions constant, only the width of the air slot was controlled at 0.5 μm, 0.7 μm, 0.9 μm, 1.1 μm, and 1.9 μm, and the waveguide loss was measured accordingly. The test results are as follows: Figure 5 As shown, the wider the air slot, the lower the waveguide loss, meaning the less the electrodes and / or blocking layer absorb the light field.
[0120] To verify the relationship between the width and depth of the air slot and the modulator bandwidth, Experiments 2 and 3 were conducted, and the results are as follows: Figure 6 and Figure 7 As shown. Figure 6 and Figure 7 The figures show the amplitude-frequency response curves for Experiments 2 and 3, respectively, where the horizontal axis represents frequency and the vertical axis represents amplitude. In the figures, m1 and m2 refer to the frequencies corresponding to the points where the frequency response decreases by 3 dB, i.e., the bandwidth.
[0121] In Experiment 2, keeping other conditions constant and the depth of the air tank 1.0 μm, only the width of the air tank was controlled to be 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.3 μm, and 1.5 μm, and the amplitude-frequency response curves corresponding to each structure were measured, as shown below. Figure 6 As shown in the figure, the widths of the air slots corresponding to curves L1, L2, L3, L4, L5, L6, and L7 are 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.3 μm, and 1.5 μm, respectively, and the depth of the air slots is 1.0 μm for all of them. It can be seen that the larger the width of the air slot, the larger the bandwidth of the modulator, that is, the smaller the microwave loss of the electrode, and the higher the matching degree between the microwave velocity and the optical velocity of the electrode.
[0122] In Experiment 3, keeping other conditions constant, the width of the air tank was 1.0 μm; only the depth of the air tank was controlled to be 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.3 μm, and 1.5 μm, and the amplitude-frequency response curves corresponding to each structure were measured, as shown below. Figure 7 As shown in the figure, the depths of the air slots corresponding to curves N1, N2, N3, N4, N5, N6, and N7 are 0.5 μm, 0.7 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.3 μm, and 1.5 μm, respectively, and the width of the air slots is 1.0 μm for all of them. It can be seen that the greater the depth of the air slot, the greater the bandwidth of the modulator, that is, the smaller the microwave loss of the electrode, and the higher the matching degree between the microwave velocity and the optical velocity of the electrode.
[0123] Therefore, under the condition of satisfying the relative relationship between the air slot and other structures, increasing the width of the air slot can reduce waveguide loss and increase the bandwidth of the modulator; increasing the depth of the air slot can more effectively increase the bandwidth of the modulator.
[0124] like Figure 8 As shown, a method for fabricating the above-mentioned heterogeneous integrated modulation device includes:
[0125] Step S101: A substrate layer 10 and a cladding layer 20 are provided stacked from bottom to top; at least one waveguide core 40 and a plurality of electrodes 50 are embedded inside the cladding layer 20; the electrodes 50 are located on both sides of each waveguide core 40 in the length direction.
[0126] Step S102: Multiple air grooves 70 are formed on the upper surface of the cladding 20 by etching openings. Each air groove 70 is located between the waveguide core 40 and the electrode 50 on its side. The depth of the air groove 70 is at least greater than the maximum depth of the waveguide core 40.
[0127] Step S103: A heterogeneous bonding layer 30 is bonded to the upper surface of the cladding 20 at the corresponding position of the waveguide core 40. The heterogeneous bonding layer 30 also covers the upper opening of the air groove 70.
[0128] In some alternative implementations, the upper surface of electrode 50 is flush with the upper surface of waveguide core 40, or the upper surface of electrode 50 is higher than the upper surface of waveguide core 40.
[0129] In some alternative embodiments, the cladding 20 is further provided with a first barrier layer 61 and a second barrier layer 62; the first barrier layer 61 covers the side and bottom surfaces of each electrode 50; and the second barrier layer 62 covers the upper surface of each electrode 50.
[0130] In some alternative embodiments, the cladding 20 includes a first cladding 21, a second cladding 22, and a third cladding 23 stacked from bottom to top, such as... Figure 9 As shown. Step S101 specifically includes:
[0131] Step S101-1: Form a first cladding layer 21 on the upper surface of the substrate layer 10;
[0132] Step S101-2: An initial waveguide layer is formed on the first cladding 21, and waveguide core 40 is formed by photolithography and etching;
[0133] Step S101-3: A second cladding 22 is formed on the upper surface of the first cladding 21. The second cladding 22 covers the side and upper surface of the waveguide core 40.
[0134] Step S101-4: Groove an electrode groove is formed on the upper surface of the second cladding 22; the electrode groove penetrates the second cladding 22 and extends into part of the first cladding 20.
[0135] Step S101-5: Deposit and form a first barrier layer 61 at the bottom and sides of the electrode groove;
[0136] Step S101-6: An electrode 50 is formed in the electrode groove and polished until the upper surface of the electrode 50 is flush with the upper surface of the waveguide core 40.
[0137] Step S101-7: A second barrier layer 62 is formed on the upper surface of the electrode 50, and the width of the second barrier layer 62 is greater than the width of the electrode 50.
[0138] Step S101-8: A third cladding layer 23 is formed on the upper surface of the second cladding layer 20. The third cladding layer 23 covers the upper surface and side surface of the second barrier layer 62. The first cladding layer 21, the second cladding layer 22 and the third cladding layer 23 constitute the cladding layer 20.
[0139] In some alternative implementations, the third cladding 23 is used to bond the heterogeneous bonding layer 30 to the waveguide core 40; the plane containing the highest point of the air slot 70 is the upper surface of the third cladding 23.
[0140] The plane containing the highest point of air trough 70 is the upper surface of the third cladding layer;
[0141] The top of the air trough 70 is in contact with the heterogeneous bonding layer 30.
[0142] In the description of this specification, the terms "this embodiment," "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0143] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.
[0144] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described above, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention. The protection scope of the present invention is determined by the scope of the appended claims.
Claims
1. A heterogeneous integrated modulation device, characterized in that, include: The substrate, cladding, and heterobonding layer are stacked from bottom to top; At least one waveguide core is embedded inside the cladding and located below the heterobonded layer; Multiple electrodes are embedded inside the cladding and located on both sides of each waveguide core along its length. Multiple air slots, each air slot located between the waveguide core and the adjacent electrode, wherein the depth of the air slot is at least greater than the maximum depth of the waveguide core.
2. The heterogeneous integrated modulation device according to claim 1, characterized in that, The plane containing the highest point of the air slot is the upper surface of the cladding; the heterogeneous bonding layer covers the upper opening of the air slot.
3. The heterogeneous integrated modulation device according to claim 1, characterized in that, The projection of the waveguide core onto the substrate layer overlaps with the projection of the heterobonded layer onto the substrate layer; the length of the air groove is greater than the length of the overlapping portion and less than or equal to the length of the electrode.
4. The heterogeneous integrated modulation device according to claim 1, characterized in that, The width of the air trough is greater than or equal to 0.5 μm; The distance between the air slot and the adjacent waveguide core is greater than or equal to the distance between the air slot and the adjacent electrode.
5. The heterogeneous integrated modulation device according to claim 4, characterized in that, The width of the waveguide core is 0.8μm to 1.5μm; The width of the electrode is 10μm to 150μm; The distance between the waveguide core and the adjacent electrode is 2μm to 4μm; The width of the air trough is 0.5μm to 2μm.
6. The heterogeneous integrated modulation device according to claim 1, characterized in that, The cladding layer is further provided with a first barrier layer and a second barrier layer; The first barrier layer covers the sides and bottom of each electrode; The second barrier layer covers the upper surface of each of the electrodes; The width of the second barrier layer is greater than the width of the electrode.
7. The heterogeneous integrated modulation device according to claim 6, characterized in that, The first barrier layer is a Ta / TaN barrier layer; The second barrier layer is a Ta / TaN barrier layer or a SiN barrier layer.
8. The heterogeneous integrated modulation device according to claim 1, characterized in that, The substrate layer is made of silicon. The waveguide core is made of silicon nitride. The electrode is made of copper. The cladding material is silicon dioxide; The material of the heterobonded layer is lithium niobate.
9. The heterogeneous integrated modulation device according to claim 1, characterized in that, The maximum depth of the electrode is greater than the maximum depth of the waveguide core; The depth of the air groove is greater than or equal to the maximum depth of the electrode; The top surface of the waveguide core is flush with the top surface of the electrode; The projection of the electrode on the vertical plane overlaps the projection of the waveguide core on the vertical plane.
10. The heterogeneous integrated modulation device according to claim 9, characterized in that, The height of the waveguide core is 200nm to 400nm; The height of the electrode is 0.8 μm to 1.5 μm; The depth of the air trough is 0.5μm to 1.5μm.