Heterogeneously integrated electro-optic modulator and method of making the same

Abstract

The embodiment of the application provides a kind of hetero-integrated electro-optic modulator and its preparation method, it is related to electro-optical integrated device technical field, wherein, the electro-optic modulator includes: lower cladding layer is located on the top surface of first substrate;Stacked waveguide core is located on the top surface of lower cladding layer, stacked waveguide core includes first layer waveguide core, intermediate layer and second layer waveguide core, and intermediate layer is arranged between first layer waveguide core and second layer waveguide core;Bonding medium layer covers on the top surface of stacked waveguide core;Electro-optic film layer is bonded on the top surface of bonding medium layer, and electro-optic film layer and at least one layer waveguide core in stacked waveguide core constitute composite waveguide core;Electrode is arranged above or below electro-optic film layer, and electrode is located on both sides of stacked waveguide core in horizontal projection.The scheme makes the structure, application of electro-optic modulator more flexible, also expands the application range or scene of electro-optic modulator.

Description

Technical Field

[0001] The present invention relates to the technical field of electro-optical integrated devices, and in particular to a heterogeneously integrated electro-optical modulator and a preparation method thereof. Background Art

[0002] Photonic platforms based on silicon waveguide cores or silicon nitride waveguide cores can realize a wide range of planar integrated devices and chip-level solutions using CMOS-compatible manufacturing processes. Phase modulators are one of the core components of photonic integrated circuits. Photonic platforms based on silicon or silicon nitride can usually use thermo-optical effects, stress-optical effects, etc. to achieve optical phase modulation. However, due to limitations in material properties such as thermal conduction speed and charge and discharge time, as well as device structure, these modulators are still insufficient in terms of speed, power, and modulation efficiency. An alternative is to use electro-optic modulation, but the electro-optical effects of silicon and silicon nitride are very weak, and must be combined with materials with significant electro-optical effects to achieve efficient electro-optical phase modulation. Ferroelectric materials have significant electro-optical effects, among which lithium niobate (LiNbO3) is a typical representative. It has a strong electro-optical effect (1550nm: r 33 =27pm / V), larger refractive index (1550nm: n o =2.21,n e =2.14), a wide light transmission window (400nm~5μm) and stable physical and chemical properties, making it the most competitive electro-optical material.

[0003] At present, due to the fact that electro-optical materials are generally difficult to etch, or there are large differences in thermal expansion coefficients with silicon substrates, potential contamination problems, etc., existing technologies for realizing electro-optic modulation on silicon or silicon nitride photonics platforms usually adopt a structure without etching the electro-optical material, and heterogeneously integrate the electro-optical material film with the silicon or silicon nitride waveguide core, that is, bonding the electro-optical material film on top of the single-layer waveguide core of silicon or silicon nitride to form a silicon-electro-optical film composite waveguide or a silicon nitride-electro-optical film composite waveguide.

[0004] Existing technology solutions use a single-layer waveguide core and electro-optical thin films to form a composite waveguide. However, the single-layer waveguide core's limited material and structure limit the functionality of optical chips. For example, silicon waveguide cores have a high refractive index and strong light field confinement, enabling high-density integration of photonic devices, but also relatively high losses. Stoichiometric silicon nitride waveguide cores offer very low propagation losses and a wide transparent window, but their relatively low refractive index and weak light field confinement, resulting in lower photonic device integration densities. Summary of the Invention

[0005] In view of this, an embodiment of the present invention provides a heterogeneously integrated electro-optic modulator to solve the technical problems of low structural flexibility and limited application of composite waveguide or electro-optic modulation devices in the prior art. The heterogeneously integrated electro-optic modulator includes:

[0006] a first substrate 1;

[0007] a lower cladding layer 2, the lower cladding layer 2 being located on the top surface of the first substrate 1;

[0008] a laminated waveguide core 3, the laminated waveguide core 3 being located on the top surface of the lower cladding layer 2, wherein the laminated waveguide core 3 comprises a first waveguide core 301, an intermediate layer 302, and a second waveguide core 303 that are stacked, with the intermediate layer 302 being disposed between the first waveguide core 301 and the second waveguide core 303;

[0009] a bonding dielectric layer 4, the bonding dielectric layer 4 covering the top surface of the laminated waveguide core 3;

[0010] an electro-optical thin film layer 501, one side of the electro-optical thin film layer 501 being bonded to the top surface of the bonding dielectric layer 4, wherein the electro-optical thin film layer 501 and at least one waveguide core layer in the stacked waveguide core 3 form a composite waveguide core, and any one or any combination of the following: different refractive indices of the electro-optical thin film layer 501, different refractive indices of the waveguide cores, different thicknesses of the waveguide cores, different widths of the waveguide cores, and different thicknesses of the intermediate layer 302, so that the electro-optical thin film layer 501 and the waveguide cores of different layers from top to bottom in the stacked waveguide core 3 form a composite waveguide core;

[0011] The electrode 6 is disposed above or below the electro-optical thin film layer 501 , and is located on both sides of the laminated waveguide core 3 in horizontal projection.

[0012] The present invention also provides a method for preparing a heterogeneously integrated electro-optic modulator to address the technical issues of low structural flexibility and limited application of composite waveguide or electro-optic modulation devices in the prior art. The method includes:

[0013] Sequentially preparing the first substrate 1 and the lower cladding layer 2;

[0014] The first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 are sequentially formed on the top surface of the lower cladding 2 to form the stacked waveguide core 3. Alternatively, two waveguide core layers and an intermediate material layer 3022 are formed at once on the top surface of the lower cladding 2, with the intermediate material layer 3022 located between the two waveguide core layers. The two waveguide core layers and the intermediate material layer 3022 are patterned to form the first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 to form the stacked waveguide core 3.

[0015] forming the bonding dielectric layer 4 on the top surface of the laminated waveguide core 3;

[0016] Bonding one side of the electro-optical thin film layer 501 to the top surface of the bonding dielectric layer 4;

[0017] An electrode 6 is formed above or below the electro-optical thin film layer 501 .

[0018] Compared with the prior art, the beneficial effects achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: it is proposed to provide a stacked waveguide core 3 in a heterogeneously integrated electro-optical modulator, wherein the stacked waveguide core 3 includes a first waveguide core 301, an intermediate layer 302, and a second waveguide core 303 arranged in a stacked manner, wherein the intermediate layer 302 is provided between the first waveguide core 301 and the second waveguide core 303, and a bonding dielectric layer 4 covers the top surface of the stacked waveguide core 3, so that the electro-optical thin film layer 501 bonded to the bonding dielectric layer 4 can form a composite waveguide core with at least one waveguide core layer in the stacked waveguide core 3, wherein the refractive index of the electro-optical thin film layer 501 is different, the refractive index of the waveguide core is different, the thickness of the waveguide core is different, the width of the waveguide core is different, and the like. and any one or any combination of the different thicknesses of the intermediate layer can make the electro-optical thin film layer 501 and the waveguide cores of different numbers from top to bottom in the stacked waveguide core 3 form a composite waveguide core. Since any one or any combination of the refractive index of the electro-optical thin film layer 501, the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core and the thickness of the intermediate layer can be adjusted and set according to specific needs, the structure of the electro-optical modulator has high flexibility. In addition, due to the flexible setting of the structure of the electro-optical modulator, different numbers of waveguide cores from top to bottom in the stacked waveguide core 3 can arbitrarily form a composite waveguide core with the electro-optical thin film layer 501, which makes the application of the electro-optical modulator more flexible and expands the application range or scenarios of the electro-optical modulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 This is a schematic diagram of the structure of a heterogeneous integrated electro-optic modulator provided by an embodiment of the present invention. Figure 1 ;

[0021] Figure 2 This is a schematic structural diagram of a lower cladding layer formed on a first substrate according to an embodiment of the present invention;

[0022] Figure 3This is a schematic structural diagram of a first waveguide core layer formed on a lower cladding layer provided by an embodiment of the present invention;

[0023] Figure 4 This is a schematic structural diagram of a patterned first waveguide core layer becoming a first layer of waveguide core provided by an embodiment of the present invention;

[0024] Figure 5 This is a schematic diagram of a structure in which an intermediate layer is formed to cover the first waveguide core and the lower cladding layer, provided by an embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of a structure in which a second waveguide core layer is formed on an intermediate layer, provided by an embodiment of the present invention;

[0026] Figure 7 1 is a schematic structural diagram of a second waveguide core layer formed by a patterned second waveguide core layer provided by an embodiment of the present invention;

[0027] Figure 8 1 is a schematic structural diagram of another patterned second waveguide core layer forming a second waveguide core according to an embodiment of the present invention;

[0028] Figure 9 This is a schematic diagram of a structure in which a bonding dielectric layer is formed to cover a second waveguide core and an intermediate layer, provided by an embodiment of the present invention;

[0029] Figure 10 This is a schematic diagram of a structure of bonding an electro-optical material wafer on a bonding dielectric layer provided by an embodiment of the present invention;

[0030] Figure 11 This is a schematic structural diagram of a method for removing a second substrate from an electro-optical material wafer provided by an embodiment of the present invention;

[0031] Figure 12 This is a schematic diagram of a structure in which an electrode is formed on a buried oxide layer above an electro-optical thin film layer, provided by an embodiment of the present invention;

[0032] Figure 13 This is a schematic diagram of a structure in which grooves are formed in the middle layer and the lower cladding on both sides of a laminated waveguide core, provided by an embodiment of the present invention;

[0033] Figure 14 This is a schematic diagram of a structure in which an electrode is formed in a groove according to an embodiment of the present invention;

[0034] Figure 15 This is a schematic diagram of a structure in which a bonding dielectric layer is formed to cover the second waveguide core, the intermediate layer, the electrode, and the portion of the groove not filled by the electrode, provided by an embodiment of the present invention;

[0035] Figure 161 is a schematic structural diagram of a bonded electro-optical thin film layer provided by an embodiment of the present invention;

[0036] Figure 17 This is a schematic structural diagram of a first substrate in which a lower cladding layer, a first waveguide core layer, an intermediate material layer, and a second waveguide core layer are sequentially formed.

[0037] Figure 18 1 is a schematic structural diagram of a laminated waveguide core formed by a patterned second waveguide core layer, an intermediate material layer, and a first waveguide core layer, provided by an embodiment of the present invention;

[0038] Figure 19 This is a schematic diagram of a structure for forming a bonding dielectric layer covering a laminated waveguide core and an intermediate layer provided by an embodiment of the present invention;

[0039] Figure 20 1 is a schematic structural diagram of a second waveguide core layer formed by a patterned second waveguide core layer provided by an embodiment of the present invention;

[0040] Figure 21 This is a schematic structural diagram of a patterned intermediate material layer and a first waveguide core layer forming a first waveguide core and an intermediate layer provided by an embodiment of the present invention;

[0041] Figure 22 This is a schematic diagram of a structure in which a bonding dielectric layer is formed to cover a second waveguide core, an intermediate layer, and a lower cladding layer, provided by an embodiment of the present invention;

[0042] Figure 23 This is a schematic diagram of the structure of a heterogeneous integrated electro-optic modulator provided by an embodiment of the present invention. Figure 2 ;

[0043] Figure 24 This is a flow chart of a method for preparing a heterogeneously integrated electro-optical modulator provided by an embodiment of the present invention.

[0044] Reference numerals in the figures:

[0045] 1. First substrate; 2. Lower cladding; 3. Laminated waveguide core; 4. Bonding dielectric layer; 5. Electro-optical material wafer; 6. Electrode; 7. Groove; 301. First waveguide core layer; 3011. First waveguide core layer; 302. Intermediate layer; 3021. Intermediate layer segment; 3022. Intermediate material layer; 303. Second waveguide core layer; 3031. Second waveguide core layer; 401. Dielectric layer segment; 501. Electro-optical thin film layer; 502. Buried oxide layer; 503. Second substrate. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0047] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0048] In an embodiment of the present invention, a heterogeneously integrated electro-optical modulator is provided, such as Figure 1 As shown in FIG, the heterogeneously integrated electro-optic modulator includes, from bottom to top:

[0049] a first substrate 1;

[0050] a lower cladding layer 2, the lower cladding layer 2 being located on the top surface of the first substrate 1;

[0051] a laminated waveguide core 3, the laminated waveguide core 3 being located on the top surface of the lower cladding layer 2, wherein the laminated waveguide core 3 comprises a first waveguide core 301, an intermediate layer 302, and a second waveguide core 303 that are stacked, with the intermediate layer 302 being disposed between the first waveguide core 301 and the second waveguide core 303;

[0052] a bonding dielectric layer 4, the bonding dielectric layer 4 covering the top surface of the laminated waveguide core 3;

[0053] an electro-optical thin film layer 501, one side of the electro-optical thin film layer 501 being bonded to the top surface of the bonding dielectric layer 4, wherein the electro-optical thin film layer 501 and at least one layer of the waveguide core in the stacked waveguide core 3 form a composite waveguide core, and any one or any combination of the following: different refractive indices of the electro-optical thin film layer 501, different refractive indices of the waveguide cores, different thicknesses of the waveguide cores, different widths of the waveguide cores, and different thicknesses of the intermediate layers, so that the electro-optical thin film layer 501 and the waveguide cores of different layers from top to bottom in the stacked waveguide core 3 form a composite waveguide core;

[0054] The electrode 6 is disposed above or below the electro-optical thin film layer 501 , and is located on both sides of the laminated waveguide core 3 in horizontal projection.

[0055] Depend on Figure 1As shown, in an embodiment of the present invention, a stacked waveguide core 3 is provided in a heterogeneously integrated electro-optical modulator. The stacked waveguide core 3 includes a first waveguide core 301, an intermediate layer 302, and a second waveguide core 303. The intermediate layer 302 is provided between the first waveguide core 301 and the second waveguide core 303. A bonding dielectric layer 4 covers the top surface of the stacked waveguide core 3, so that the electro-optical thin film layer 501 bonded to the bonding dielectric layer 4 can form a composite waveguide core with at least one waveguide core in the stacked waveguide core 3. Any of the different refractive indices of the electro-optical thin film layer 501, the different refractive indices of the waveguide cores, the different thicknesses of the waveguide cores, the different widths of the waveguide cores, and the different thicknesses of the intermediate layers can be used. Any one or any combination of the above can make the electro-optical thin film layer 501 and the waveguide cores of different numbers from top to bottom in the stacked waveguide core 3 form a composite waveguide core. Since any one or any combination of the refractive index of the electro-optical thin film layer 501, the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core and the thickness of the intermediate layer can be adjusted and set according to specific needs, the structure of the electro-optical modulator has high flexibility. In addition, due to the flexible setting of the structure of the electro-optical modulator, different numbers of waveguide cores from top to bottom in the stacked waveguide core 3 can arbitrarily form a composite waveguide core with the electro-optical thin film layer 501, which makes the application of the electro-optical modulator more flexible and expands the application scope or scenario of the electro-optical modulator.

[0056] In specific implementation, in order to further improve the flexibility of the structure, setting, and application of the heterogeneously integrated electro-optical modulator, it is proposed that the materials of the first waveguide core 301 and the second waveguide core 303 can be the same or different. However, the refractive index of each of the first waveguide core 301 and the second waveguide core 303 needs to be greater than the refractive index of the lower cladding 2 and the refractive index of the intermediate layer 302, respectively.

[0057] Specifically, the material of the first waveguide core 301 can be any one of stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., and the material of the second waveguide core 303 can be any one of stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc.

[0058] In a specific implementation, in order to further improve the flexibility of the structure, setting, and application of the heterogeneously integrated electro-optical modulator, it is proposed that the widths of the first layer waveguide core 301 and the second layer waveguide core 303 may be the same or different, for example, Figure 1 As shown, the widths of the first waveguide core 301 and the second waveguide core 303 are the same; in the case where the widths of the first waveguide core 301 and the second waveguide core 303 are different, as shown in FIG. Figure 7As shown, the width of the first layer waveguide core 301 may be smaller than the width of the second layer waveguide core 303, as shown in FIG. Figure 21 As shown, the width of the first waveguide core 301 may be greater than the width of the second waveguide core 303. Regardless of whether the widths of the first waveguide core 301 and the second waveguide core 303 are the same, the first waveguide core 301 and the second waveguide core 303 must overlap in horizontal projection, and the overlap may be complete or partial.

[0059] Specifically, the complete overlap means that the second layer of waveguide cores 303 are completely located within the range of the first layer of waveguide cores 301 in horizontal projection (e.g. Figure 1 As shown, at this time, the width of the first layer waveguide core 301 is equal to the width of the second layer waveguide core 303, Figure 21 As shown, at this time, the width of the first layer waveguide core 301 is greater than the width of the second layer waveguide core 303, and the second layer waveguide core 303 is located directly above the first layer waveguide core 301), or, in horizontal projection, the second layer waveguide core 303 completely covers the first layer waveguide core 301 (that is, the first layer waveguide core 301 is completely located within the range of the second layer waveguide core 303, as shown in FIG. Figure 7 As shown, at this time, the width of the first layer waveguide core 301 is smaller than the width of the second layer waveguide core 303, and the second layer waveguide core 303 is located directly above the first layer waveguide core 301).

[0060] Specifically, the partial overlap means that the second layer waveguide core 303 partially covers the first layer waveguide core 301 in horizontal projection (or the first layer waveguide core 301 is partially located within the range of the second layer waveguide core 303). Figure 8 As shown, at this time, the second layer waveguide core 303 is partially located above the first layer waveguide core 301, or in other words, the central axes of the second layer waveguide core 303 and the first layer waveguide core 301 in the vertical direction are inconsistent or do not overlap.

[0061] In a specific implementation, in order to further improve the flexibility of the structure, setting, and application of the heterogeneously integrated electro-optical modulator, it is proposed that the thicknesses of the first waveguide core 301 and the second waveguide core 303 may be the same or different.

[0062] Specifically, the thickness of the first layer of waveguide core 301 may be equal to the thickness of the second layer of waveguide core 303; Figure 7 As shown, the thickness of the first waveguide core 301 may be smaller than the thickness of the second waveguide core 303 ; or the thickness of the first waveguide core 301 may be larger than the thickness of the second waveguide core 303 .

[0063] In a specific implementation, the thickness of each of the first layer waveguide core 301 and the second layer waveguide core 303 may be in the range of 10 to 500 nm.

[0064] In specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneous integrated electro-optical modulator, it is proposed that the thickness of the intermediate layer segment 3021 located above the first waveguide core 301 in the intermediate layer 302 is in the range of 10 to 300 nm. Figure 5 As shown, the middle layer segment 3021 is only a segment of the middle layer 302. Figure 18 、 Figure 21 As shown, at this time, the middle layer section 3021 and the middle layer 302 are the same section structure.

[0065] In a specific implementation, in order to further improve the flexibility of the structure, setting, and application of the heterogeneously integrated electro-optical modulator, it is proposed that the width of the intermediate layer 302 can be the same as the width of the lower cladding layer 2, and cover the first waveguide core 301 and the lower cladding layer 2, such as Figure 5 Alternatively, the width of the intermediate layer 302 may be the same as the width of the first waveguide core 301, as shown Figure 18 、 Figure 21 shown.

[0066] In specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneously integrated electro-optic modulator, it is proposed that the intermediate layer 302 can be made of a material with a refractive index smaller than that of the first waveguide core 301, such as silicon dioxide.

[0067] In specific implementation, in order to further improve the flexibility of the structure, setting and application of the heterogeneous integrated electro-optic modulator, it is proposed that the electrode 6 can be arranged above the electro-optic thin film layer 501 (such as Figure 1 as shown) or below (as shown Figure 16 shown).

[0068] In a specific implementation, the material of the electro-optical thin film layer 501 can be any one of the electro-optical materials such as lithium niobate, lithium tantalate, and barium titanate.

[0069] In a specific implementation, the material of the first waveguide core 301 and the second waveguide core 303 is silicon nitride, and the material of the electro-optical thin film layer 501 is lithium niobate.

[0070] In a specific implementation, in order to further improve the flexibility of the structure, setting, and application of the heterogeneously integrated electro-optic modulator, any one or any combination of the refractive index of the electro-optic thin film layer 501, the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core, and the thickness of the intermediate layer 302 can be set differently to change the structural flexibility of the electro-optic modulator, so that the electro-optic thin film layer 501 and the waveguide cores of different layers from top to bottom in the stacked waveguide core 3 form a composite waveguide core. For example, the electro-optic thin film layer 501 and the second layer of waveguide core 303 form a composite waveguide core, or the electro-optic thin film layer 501 and the entire stacked waveguide core 3 form a composite waveguide core.

[0071] In specific implementation, under the premise that the second-layer waveguide core 303 can form a composite waveguide core with the electro-optical thin film layer 501, any one of the following items or any combination of items can be set to make it more likely that the first-layer waveguide core 301 in the stacked waveguide core 3 and the electro-optical thin film layer 501 form a composite waveguide core (that is, the electro-optical thin film layer 501 and the entire stacked waveguide core 3 form a composite waveguide core): the refractive index of the first-layer waveguide core 301 is increased, the width of the first-layer waveguide core 301 is increased, the thickness of the first-layer waveguide core 301 is increased, the thickness of the intermediate layer 302 is reduced, the refractive index of the second-layer waveguide core 303 is increased, the thickness of the second-layer waveguide core 303 is increased, the width of the second-layer waveguide core 303 is increased, the thickness of the bonding medium layer 4 is reduced, the refractive index of the electro-optical thin film layer 501 is reduced, and the thickness of the electro-optical thin film layer 501 is reduced.

[0072] In specific implementation, the above-mentioned preparation method of heterogeneous integrated electro-optical modulator can fully utilize CMOS compatible manufacturing process, such as Figure 24 As shown, the preparation method includes: preparing a laminated waveguide core 3, preparing or pre-preparing an electro-optic material wafer 5 having an electro-optic thin film layer 501, and bonding the electro-optic thin film layer 501 to the prepared laminated waveguide core 3 and forming an electrode 6. Examples 1 to 3 are only examples of three preferred methods for preparing the laminated waveguide core 3. In other preferred methods, the laminated waveguide core 3 can also be prepared by patterning the laminate once or multiple times. The specific method can refer to the following steps:

[0073] Step S2401: preparing the first substrate 1 and the lower cladding layer 2 in sequence;

[0074] Step S2402: sequentially forming the first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 on the top surface of the lower cladding 2 to form the stacked waveguide core 3; alternatively, forming two waveguide core layers and an intermediate material layer 3022 at once on the top surface of the lower cladding 2, with the intermediate material layer 3022 located between the two waveguide core layers, and patterning the two waveguide core layers and the intermediate material layer 3022 (either patterning the two waveguide core layers and the intermediate material layer once or patterning the two waveguide core layers and the intermediate material layer multiple times) to form the first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 to form the stacked waveguide core 3;

[0075] Step S2403: forming the bonding dielectric layer 4 on the top surface of the laminated waveguide core 3;

[0076] Step S2404: bonding one side of the electro-optic thin film layer 501 to the top surface of the bonding dielectric layer 4 (for example, by bonding one side of the electro-optic thin film layer 501 in the electro-optic material wafer 5 to the top surface of the bonding dielectric layer 4, and then removing the second substrate 503 in the electro-optic material wafer 5 to complete the bonding of the electro-optic thin film layer 501);

[0077] Step S2405 : forming an electrode 6 on or below the electro-optical thin film layer 501 .

[0078] In a specific implementation, forming the electrode 6 above or below the electro-optical thin film layer 501 includes:

[0079] When forming the electrode 6 above the electro-optic thin film layer 501, after bonding one side of the electro-optic thin film layer 501 to the top surface of the bonding dielectric layer 4, the electrode 6 is formed on the top surface of the buried oxide layer 502 above the electro-optic thin film layer 501; or

[0080] When the electrode 6 is formed below the electro-optical thin film layer 501, after the laminated waveguide core 3 is formed, grooves 7 are formed on both sides of the laminated waveguide core 3, a metal layer is deposited and patterned, and the electrode 6 is formed in the groove 7. Then, the bonding dielectric layer 4 is formed on the top surface of the laminated waveguide core 3. The bonding dielectric layer 4 covers the second waveguide core 303 of the laminated waveguide core 3, the electrode 6, and the portion of the groove 7 not filled with the electrode, and the bonding dielectric layer 4 is flattened.

[0081] In a specific implementation, Example 1: For a situation where the widths of the first waveguide core 301 and the second waveguide core 303 are different and partially overlap in horizontal projection, the method for preparing the heterogeneously integrated electro-optical modulator may include the following steps:

[0082] ① Such as Figure 2 As shown, a lower cladding layer 2 is formed on the first substrate 1; Figure 3 As shown, a first waveguide core layer 3011 is formed on the lower cladding layer 2; Figure 4 As shown, the patterned first waveguide core layer 3011 becomes the first waveguide core 301; wherein the material of the first substrate 1 can be silicon; the material of the lower cladding layer 2 can be silicon dioxide, and the thickness can be 2 to 20 μm; the material of the first waveguide core 301 can be a material with a greater refractive index than the lower cladding layer 2, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., and the thickness of the first waveguide core 301 can range from 10 to 500 nm;

[0083] ② If Figure 5 As shown, an intermediate material layer 3022 is formed to cover the first waveguide core 301 and the lower cladding layer 2, and the intermediate material layer 3022 is flattened. The intermediate material layer 3022 may be made of a material having a refractive index lower than that of the first waveguide core 301, such as silicon dioxide. In this case, the intermediate material layer 3022 is not etched and serves as the intermediate layer 302. The thickness of the intermediate layer section 3021 of the intermediate layer 302 located above the first waveguide core 301 may be in the range of 10 to 300 nm.

[0084] ③ Such as Figure 6 As shown, a second waveguide core layer 3031 is formed on the intermediate layer 302; Figure 7 As shown, the second waveguide core layer 3031 is patterned to form the second waveguide core 303. The material of the second waveguide core 303 can be a material having a greater refractive index than the lower cladding layer 2 and the intermediate layer 302, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc. The thickness of the second waveguide core 303 ranges from 10 to 500 nm. The material (refractive index, etc.), thickness, and width of the second waveguide core can be the same as or different from those of the first waveguide core 301. Since the first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 are formed in different steps, it is convenient to determine whether the widths of the first waveguide core 301 and the second waveguide core 303 are the same or different, and it is also convenient to determine whether the second waveguide core 303 is directly above the first waveguide core 301. Figure 7 For example, the widths of the first waveguide core 301 and the second waveguide core 303 are different. The width of the first waveguide core 301 is smaller than the width of the second waveguide core 303. In horizontal projection, the first waveguide core 301 is completely within the range of the second waveguide core 303 (i.e., the second waveguide core 303 is wider than the first waveguide core 301 and is located directly above the first waveguide core 301). Alternatively, Figure 8As shown, in horizontal projection, the first waveguide core 301 can also be partially located within the range of the second waveguide core 303 (that is, the second waveguide core 303 covers part of the first waveguide core 301); the first waveguide core, the middle layer, and the second waveguide core constitute a stacked waveguide core;

[0085] ④ Such as Figure 9 As shown, a bonding dielectric layer 4 is formed to cover the second waveguide core 303 and the intermediate layer 302, and the bonding dielectric layer 4 is flattened. The bonding dielectric layer 4 may be made of a material having a refractive index smaller than that of the first waveguide core 301 and the second waveguide core 303, such as a single layer or a stack of silicon dioxide, aluminum oxide, bonding adhesive, or the like. The thickness of the dielectric layer segment 401 of the bonding dielectric layer 4 located above the second waveguide core 303 may be in the range of 10 to 300 nm.

[0086] ⑤ Bonding the electro-optical thin film layer 501 on the bonding dielectric layer 4;

[0087] The electro-optical thin film layer 501 can be bonded to the bonding medium layer 4 of the first substrate 1 by bonding the electro-optical thin film layer of the wafer 5 having the electro-optical thin film layer / buried oxide layer / second substrate structure or the electro-optical thin film layer of the small pieces cut from the wafer (e.g. Figure 10 As shown), and then remove the second substrate 503 to form (as shown Figure 11 As shown); it can also be formed by a smart ion slicing process or a wafer thinning process of a bonded electro-optic material wafer; the electro-optic thin film layer 501 can be made of lithium niobate, lithium tantalate, barium titanate, etc.; the thickness of the electro-optic thin film layer 501 ranges from 100 to 500 nm;

[0088] ⑥ Such as Figure 12 As shown, electrodes 6 are formed above the buried oxide layer 502 on the electro-optical thin film layer 501. In horizontal projection, the electrodes 6 are located on both sides of the laminated waveguide core 3. The material of the electrodes 6 can be Au, Al, Cu, etc. The distance between the two electrodes 6 can be 4 to 10 μm, and the thickness of the electrodes 6 ranges from 0.5 to 2 μm.

[0089] In a specific implementation, the electrode 6 can be formed not only on the electro-optical thin film layer 501 but also below the electro-optical thin film layer 501. For example, after step ③ and before step ④ (i.e., the electrode 6 is formed after the second waveguide core 303 is formed and before the bonding medium layer 4 is formed), the electrode 6 is formed by the following process flow:

[0090] 1) After the second waveguide core 303 is formed, grooves 7 are formed in the middle layer 302 and the lower cladding layer 2 on both sides of the laminated waveguide core 3, as shown in FIG. Figure 13 As shown;

[0091] 2) Deposit a metal layer and pattern it to form an electrode 6 in the groove 7, as shown in FIG. Figure 14 As shown;

[0092] 3) forming a bonding dielectric layer 4 to cover the second waveguide core 303, the intermediate layer 302, the electrode 6 and the portion of the groove 7 not filled by the electrode, and flattening the bonding dielectric layer 4, as shown in FIG. Figure 15 As shown;

[0093] 4) If Figure 16 As shown, the electro-optical thin film layer 501 is bonded to complete the preparation of the electro-optical modulator.

[0094] In specific implementation, Example 2: For the case where the upper and lower waveguide cores of the stacked waveguide core 3 are patterned in one step, the above-mentioned electro-optical modulator is prepared by the following steps:

[0095] ① Such as Figure 17 As shown, a lower cladding layer 2, a first waveguide core layer 3011, an intermediate material layer 3022, and a second waveguide core layer 3031 are sequentially formed on a first substrate 1, that is, the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022, and the second waveguide core layer 3031 are formed at once in one step; wherein the material of the first substrate 1 can be silicon; the material of the lower cladding layer 2 can be silicon dioxide, and the thickness of the lower cladding layer 2 can be 2 to 20 μm; the material of the first waveguide core layer 3011 and the second waveguide core layer 3031 can be a material having a refractive index greater than that of the lower cladding layer 2 and the intermediate material layer 3022, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc.; the thickness of the first waveguide core layer 3011 and the second waveguide core layer 3031 ranges from 10 to 500 nm, and the materials (refractive index, etc.) and thicknesses of the two can be the same or different; the thickness of the intermediate material layer 3022 ranges from 10 to 300 nm;

[0096] ② If Figure 18 As shown, the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 are patterned to form the second waveguide core 303, the intermediate layer 302 and the first waveguide core 301; wherein the laminated waveguide core 3 is composed of the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303 from bottom to top; specifically, although the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022 and the second waveguide core layer 3031 are formed at once in one step, in the process of forming the laminated waveguide core 3, the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 can be etched at one time to form the laminated waveguide core 3 with the same width as the first waveguide core 301, the intermediate layer 302 and the second waveguide core 303, as shown in FIG. Figure 18 As shown; the second waveguide core layer 3031, the intermediate material layer 3022 and the first waveguide core layer 3011 may also be sequentially etched to form a first waveguide core 301, an intermediate layer 302 and a second waveguide core 303 with different widths of a laminated waveguide core 3;

[0097] ③ Such as Figure 19 As shown, based on Figure 18 A bonding dielectric layer 4 is formed in a structure covering the second waveguide core 303 and the lower cladding 2 of the stacked waveguide core 3, and the bonding dielectric layer 4 is flattened. The bonding dielectric layer 4 can be made of a material having a refractive index lower than that of the first waveguide core 301 and the second waveguide core 303, such as a single layer or a stack of silicon dioxide, aluminum oxide, bonding adhesive, or the like. The thickness of the dielectric layer segment 401 of the bonding dielectric layer 4 located above the second waveguide core 303 is in the range of 10 to 300 nm.

[0098] ④ Bonding the electro-optical thin film layer 501 on the bonding dielectric layer 4; forming an electrode 6 above the buried oxide layer 502 on the electro-optical thin film layer 501, thereby completing the preparation of the electro-optical modulator. Figure 1 As shown; wherein, the electro-optical thin film layer 501 can be formed by bonding one side of the electro-optical thin film layer of a wafer 5 having an electro-optical thin film layer 501 / buried oxide layer 502 / second substrate 503 structure or a small piece cut from the wafer to the bonding dielectric layer 4 of the first substrate 1, and then removing the second substrate 503 to form an electrode 6 (as shown in FIG. Figure 1 As shown); it can also be formed by a smart ion slicing process or a wafer thinning process of a bonded electro-optic material wafer; the electro-optic thin film layer 501 can be lithium niobate, lithium tantalate, barium titanate, etc.; the thickness of the electro-optic thin film layer 501 ranges from 100 to 500 nm; the material of the electrode 6 can be Au, Al, Cu, etc., the distance between the two electrodes 6 is 4 to 10 μm, and the thickness of the electrode 6 ranges from 0.5 to 2 μm;

[0099] Specifically, the electrode 6 may be located on the electro-optical thin film layer 501 (eg Figure 1 As shown), it can also be located under the electro-optical thin film layer 501, and the electrode 6 can be formed according to steps 1) to 4) of Example 1 (the electrode 6 is made after the laminated waveguide core 3 is formed and before the bonding dielectric layer 4 is formed. At this time, grooves 7 are formed on the lower cladding 2 on both sides of the laminated waveguide core 3, and the electrode 6 is formed in the groove 7. Then, the bonding dielectric layer 4 is formed to cover the second waveguide core 303 of the laminated waveguide core 3, the lower cladding 2, the electrode 6 and the part of the groove 7 that is not filled with the electrode).

[0100] In specific implementation, Example 3: For the case where the lower waveguide core of the stacked waveguide core 3 is wider than the upper waveguide core, and the upper waveguide core is completely located within the range of the lower waveguide core in horizontal projection, the above-mentioned electro-optical modulator is prepared by the following steps:

[0101] ① On the first substrate 1, the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022 and the second waveguide core layer 3031 are formed in sequence at one time. Figure 17As shown; wherein, the material of the first substrate 1 can be silicon; the material of the lower cladding layer 2 can be silicon dioxide, and the thickness of the lower cladding layer 2 is 2 to 20 μm; the material of the first waveguide core layer 3011 and the material of the second waveguide core layer 3031 can be a material having a refractive index greater than that of the lower cladding layer 2 and the intermediate material layer 3022, such as stoichiometric silicon nitride, silicon-rich silicon nitride, silicon, etc., and the thickness of the first waveguide core layer 3011 and the second waveguide core layer 3031 ranges from 10 to 500 nm, and the materials (refractive index, etc.) and thicknesses of the two can be the same or different; the thickness of the intermediate material layer 3022 is 10 to 300 nm;

[0102] ② If Figure 20 As shown, the second waveguide core layer 3031 is patterned to form a second waveguide core 303;

[0103] ③ Such as Figure 21 As shown, the intermediate material layer 3022 and the first waveguide core layer 3011 are patterned to form the first waveguide core 301 and the intermediate layer 302. Specifically, although the lower cladding layer 2, the first waveguide core layer 3011, the intermediate material layer 3022, and the second waveguide core layer 3031 are formed at once in one step, in the process of forming the laminated waveguide core 3, the second waveguide core layer 3031, the intermediate material layer 3022, and the first waveguide core layer 3011 can also be etched in sequence to form the laminated waveguide core 3 in which the first waveguide core 301, the intermediate layer 302, and the second waveguide core 303 have different widths (mainly in the case where the width of the first waveguide core 301 is greater than the width of the second waveguide core 303). Figure 21 As shown, the width of the first layer waveguide core 301 is greater than the width of the second layer waveguide core 303, and the width of the middle layer 302 is equal to the width of the first layer waveguide core 301;

[0104] ④ Such as Figure 22 As shown, based on Figure 21 A bonding dielectric layer 4 is formed in a structure covering the second waveguide core 303, the intermediate layer 302 and the lower cladding layer 2, and the bonding dielectric layer 4 is flattened. The bonding dielectric layer 4 can be made of a material having a refractive index lower than that of the first waveguide core 301 and the second waveguide core 303, such as a single layer or a stack of materials such as silicon dioxide, aluminum oxide, and bonding adhesive. The thickness of the dielectric layer segment 401 of the bonding dielectric layer 4 located above the second waveguide core 303 is in the range of 10 to 300 nm.

[0105] ⑤ If Figure 23As shown, an electro-optical thin film layer 501 is bonded to the bonding dielectric layer 4; an electrode 6 is formed above the buried oxide layer 502 on the electro-optical thin film layer 501 to complete the preparation of the above-mentioned electro-optic modulator; wherein the electro-optical thin film layer 501 can be formed by bonding one side of the electro-optical thin film layer 501 of a wafer 5 having an electro-optical thin film layer 501 / buried oxide layer 502 / second substrate 503 or a small piece of the wafer cut into the electro-optical thin film layer 501 to one side of the bonding dielectric layer 4 of the first substrate 1, and then removing the second substrate 503, and forming the electrode 6 above the buried oxide layer 502 (as shown in FIG. Figure 23 As shown); it can also be formed by a smart ion slicing process or a wafer thinning process of a bonded electro-optic material wafer; the electro-optic thin film layer 501 can be lithium niobate, lithium tantalate, barium titanate, etc.; the thickness of the electro-optic thin film layer 501 is 100 to 500 nm; the material of the electrode 6 can be Au, Al, Cu, etc., the distance between the two electrodes 6 is 4 to 10 μm, and the thickness of the electrode 6 ranges from 0.5 to 2 μm;

[0106] Specifically, the electrode 6 may be located on the electro-optical thin film layer 501 (eg Figure 23 As shown), it can also be located under the electro-optical thin film layer 501, and the electrode 6 can be formed according to steps 1) to 4) of Example 1 (the electrode 6 is made after the laminated waveguide core 3 is formed and before the bonding dielectric layer 4 is formed. At this time, grooves 7 are formed on the lower cladding 2 on both sides of the laminated waveguide core 3, and the electrode 6 is formed in the groove 7. Then, the bonding dielectric layer 4 is formed to cover the second waveguide core 303 of the laminated waveguide core 3, the intermediate layer 302, the lower cladding 2, the electrode 6 and the portion of the groove 7 that is not filled with the electrode).

[0107] The embodiments of the present invention achieve the following technical effects: the present application adopts heterogeneous integration of a stacked waveguide core and an electro-optical thin film to form a composite waveguide core or an electro-optical modulator device. Since the first waveguide core and the second waveguide core of the stacked waveguide can have different or the same materials (properties such as refractive index), width, thickness, etc., the composite waveguide or electro-optical modulator device composed of the stacked waveguide core and the electro-optical thin film can have higher flexibility and application expansion.

[0108] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A heterogeneously integrated electro-optic modulator, characterized in that: The heterogeneously integrated electro-optical modulator comprises, from bottom to top: a first substrate (1); A lower cladding layer (2), the lower cladding layer (2) being located on the top surface of the first substrate (1); A laminated waveguide core (3), the laminated waveguide core (3) being located on the top surface of the lower cladding layer (2), wherein the laminated waveguide core (3) comprises a first layer of waveguide core (301), an intermediate layer (302), and a second layer of waveguide core (303) arranged in a laminated manner, and the intermediate layer (302) is arranged between the first layer of waveguide core (301) and the second layer of waveguide core (303); a bonding dielectric layer (4), the bonding dielectric layer (4) covering the top surface of the laminated waveguide core (3); An electro-optical film layer (501), one side of the electro-optical film layer (501) is bonded to the top surface of the bonding medium layer (4), wherein the electro-optical film layer (501) and at least one layer of waveguide core in the stacked waveguide core (3) form a composite waveguide core, and any one or any combination of the refractive index of the electro-optical film layer (501), the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core, and the thickness of the intermediate layer (302) are set differently, so that any one or any combination of the refractive index of the electro-optical film layer (501), the refractive index of the waveguide core, the thickness of the waveguide core, the width of the waveguide core, and the thickness of the intermediate layer (302) are different, so that the electro-optical film layer (501) and the waveguide cores of different layers from top to bottom in the stacked waveguide core (3) form a composite waveguide core, and the electro-optical film layer (501) Together with the second layer of waveguide core (303), a composite waveguide core is formed; or, the electro-optical thin film layer (501) and the entire stacked waveguide core (3) form a composite waveguide core; An electrode (6), wherein the electrode (6) is arranged above or below the electro-optical thin film layer (501), and in horizontal projection, the electrode (6) is located on both sides of the stacked waveguide core (3).

2. The heterogeneously integrated electro-optical modulator according to claim 1, wherein: The materials of the first waveguide core (301) and the second waveguide core (303) are the same or different, and the refractive index of each of the first waveguide core (301) and the second waveguide core (303) is greater than the refractive index of the lower cladding (2) and the refractive index of the intermediate layer (302).

3. The heterogeneously integrated electro-optic modulator according to claim 1, wherein: The widths of the first layer of waveguide cores (301) and the second layer of waveguide cores (303) are the same or different, and in horizontal projection, the first layer of waveguide cores (301) and the second layer of waveguide cores (303) overlap.

4. The heterogeneously integrated electro-optic modulator according to claim 1, wherein: The thicknesses of the first layer of waveguide core (301) and the second layer of waveguide core (303) are the same or different.

5. The heterogeneously integrated electro-optic modulator according to claim 1, wherein: The thickness of each of the first layer waveguide core (301) and the second layer waveguide core (303) is in the range of 10 to 500 nm.

6. The heterogeneously integrated electro-optic modulator according to claim 1, wherein: The thickness of the intermediate layer segment (3021) in the intermediate layer (302) located above the first waveguide core (301) is in the range of 10 to 300 nm.

7. The heterogeneously integrated electro-optic modulator according to claim 1, wherein: The width of the intermediate layer is the same as the width of the lower cladding layer (2), and covers the first waveguide core (301) and the lower cladding layer (2); or the width of the intermediate layer (302) is the same as the width of the first waveguide core (301).

8. The heterogeneously integrated electro-optical modulator according to any one of claims 1 to 7, characterized in that: The material of the first waveguide core (301) and the second waveguide core (303) is silicon nitride, and the material of the electro-optical thin film layer (501) is lithium niobate.

9. A method for preparing a heterogeneously integrated electro-optical modulator according to any one of claims 1 to 8, characterized in that: include: The first substrate (1) and the lower cladding layer (2) are prepared in sequence; The first waveguide core (301), the intermediate layer (302), and the second waveguide core (303) are sequentially formed on the top surface of the lower cladding (2) to form the laminated waveguide core (3); or, two waveguide core layers and an intermediate material layer (3022) are formed at once on the top surface of the lower cladding (2), the intermediate material layer (3022) being located between the two waveguide core layers, and the two waveguide core layers and the intermediate material layer (3022) are patterned to form the first waveguide core (301), the intermediate layer (302), and the second waveguide core (303) to form the laminated waveguide core (3); forming the bonding dielectric layer (4) on the top surface of the laminated waveguide core (3); Bonding one side of the electro-optical thin film layer (501) to the top surface of the bonding medium layer (4); An electrode (6) is formed above or below the electro-optical thin film layer (501).

10. The preparation method according to claim 9, wherein An electrode (6) is formed above or below the electro-optical thin film layer (501), comprising: When forming the electrode (6) above the electro-optic thin film layer (501), after bonding one side of the electro-optic thin film layer (501) to the top surface of the bonding dielectric layer (4), the electrode (6) is formed on the top surface of the buried oxide layer (502) above the electro-optic thin film layer (501); or When forming the electrode (6) below the electro-optical thin film layer (501), after forming the laminated waveguide core (3), grooves (7) are formed on both sides of the laminated waveguide core (3), a metal layer is deposited and patterned, and an electrode (6) is formed in the groove (7), and then the bonding dielectric layer (4) is formed on the top surface of the laminated waveguide core (3), the bonding dielectric layer (4) covers the second waveguide core (303) of the laminated waveguide core (3), the electrode (6) and the portion of the groove (7) not filled by the electrode, and the bonding dielectric layer (4) is flattened.

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