Electro-optic modulator and method of manufacturing the same

Abstract

This invention relates to the field of semiconductor technology, and provides an electro-optic modulator and its manufacturing method. In one embodiment, the electro-optic modulator includes a hybrid waveguide and electrodes located on both sides of the hybrid waveguide. The manufacturing method includes: providing a first component, the first component comprising at least a silicon layer and conductive wiring structures located on both sides of the silicon layer; providing a second component, the second component comprising a nonlinear optical material layer and conductive wiring structures located on both sides of the nonlinear optical material layer; bonding the first component and the second component together, wherein the silicon layer and the nonlinear optical material layer are stacked together to form the hybrid waveguide, and the conductive wiring structures located on both sides of the silicon layer are electrically connected to the conductive wiring structures located on both sides of the nonlinear optical material layer to form the electrodes. Using the embodiments of this invention, a small-size, high-efficiency, low-power electro-optic modulator can be integrated into a silicon photonic chip.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to an electro-optic modulator and its manufacturing method. Background Technology

[0002] In the field of photonic computing, improving the energy efficiency of computation is a crucial issue. Electro-optic modulators are the core components for realizing optical computing and are highly multiplexed devices in optoelectronic chips, typically integrating thousands or even tens of thousands of them. Reducing their power consumption is one of the key challenges in improving the energy efficiency of photonic computing.

[0003] Currently, modulators commonly used in silicon photonics chips are typically based on carrier dispersion effects. Modulation methods include carrier injection (forward bias) and depletion (reverse bias). Modulator forms include micro-ring modulators or Mach-Zehnder interferometers (MZIs). Micro-ring modulators are difficult to implement with high precision due to their sensitivity to wavelength and temperature, and their overall power consumption remains high due to additional heating and feedback control circuitry. Injection-type MZIs have high modulation efficiency, which is beneficial for high-density integration, but they generate a large DC current (milliamperes) during operation, resulting in high static power consumption. Depletion-type MZIs have lower modulation efficiency, larger size, and are unsuitable for photonic computing in terms of power consumption and integration density due to the presence of terminal loads. Summary of the Invention

[0004] This invention provides an electro-optic modulator and its manufacturing method, which can integrate a small-size, high-efficiency, and low-power electro-optic modulator into a silicon photonic chip.

[0005] An embodiment of the present invention provides an electro-optic modulator, comprising:

[0006] A hybrid waveguide comprising stacked silicon layers and nonlinear optical material layers; and

[0007] The electrode includes a first electrode and a second electrode disposed on both sides of the hybrid waveguide.

[0008] The hybrid waveguide has coupling ends extending from both ends for optical coupling.

[0009] At least one of the coupling ends at both ends of the hybrid waveguide includes a gradient structure.

[0010] In some embodiments, the nonlinear optical material layer includes at least one of the following: a barium titanate layer, a lithium niobate layer, a lithium tantalate layer, and an organic polymer layer; and / or, the silicon layer includes at least one of the following: a single-crystal silicon layer and a silicon nitride layer.

[0011] In some embodiments, in the hybrid waveguide, the vertical projection of the silicon layer lies within the vertical projection range of the nonlinear optical material layer.

[0012] In some embodiments, the gradient structure includes:

[0013] A base, which is connected to the hybrid waveguide and includes stacked silicon layers and nonlinear optical material layers, optionally, the silicon layers and nonlinear optical material layers included in the base are dimensionally consistent with the silicon layers and nonlinear optical material layers included in the hybrid waveguide;

[0014] A deformable portion, which is connected to the base and includes a stacked silicon layer and a nonlinear optical material layer, wherein the nonlinear optical material layer included in the deformable portion extends from the nonlinear optical material layer included in the base and its size gradually decreases in the direction away from the base, and the silicon layer included in the deformable portion extends from the silicon layer included in the base and its size remains constant.

[0015] In other embodiments, the gradient structure includes:

[0016] The base is connected to the hybrid waveguide and comprises stacked silicon layers and nonlinear optical material layers;

[0017] The middle portion, which is connected to the base portion, includes stacked silicon layers and nonlinear optical material layers;

[0018] The deformable portion is connected to the intermediate portion and includes stacked silicon layers and nonlinear optical material layers;

[0019] In the intermediate portion, the silicon layer includes a silicon layer extending from the deformed portion and a silicon layer extending from the base portion, with the silicon layer extending from the deformed portion located above the silicon layer extending from the base portion; the nonlinear optical material layer included in the deformed portion extends from the nonlinear optical material layer included in the intermediate portion and its size gradually decreases in the direction away from the intermediate portion.

[0020] In some embodiments, the end face of the nonlinear optical material layer included in the deformable portion includes an inclined surface.

[0021] In some embodiments, when viewed from above, the inclined surface of the nonlinear optical material layer included in the deformed portion forms an angle with its included silicon layer. Optionally, the angle is less than 45°.

[0022] In some embodiments, in the intermediate portion, the thickness of the silicon layer extending from the deformed portion is greater than the thickness of the silicon layer extending from the base portion.

[0023] In some embodiments, in the intermediate portion, the width of the silicon layer extending from the deformed portion is smaller than the width of the silicon layer extending from the base portion.

[0024] In some embodiments, when viewed from above, the width of the silicon layer extending from the base in the middle portion gradually increases and then gradually decreases along the extension direction.

[0025] In some embodiments, when viewed from above, the width of the tail of the silicon layer extending from the deformed portion in the middle portion gradually decreases along the extension direction.

[0026] In some embodiments, the electro-optic modulator includes at least two of the hybrid waveguides, at least one beamsplitter, and at least one beam combiner. The output of the beamsplitter is coupled to the input side of the corresponding hybrid waveguide via a first connecting waveguide, and the input of the beam combiner is coupled to the output side of the corresponding hybrid waveguide via a second connecting waveguide.

[0027] Furthermore, embodiments of the present invention provide a method for manufacturing an electro-optic modulator, wherein the manufacturing method is adapted to manufacture the electro-optic modulator described in any of the above embodiments, the electro-optic modulator comprising a hybrid waveguide and electrodes located on both sides of the hybrid waveguide, and the manufacturing method comprising:

[0028] A first component is provided, the first component comprising at least a silicon layer and conductive wiring structures located on both sides of the silicon layer;

[0029] A second component is provided, the second component comprising a nonlinear optical material layer and conductive wiring structures located on both sides of the nonlinear optical material layer;

[0030] The first component and the second component are bonded together to form the electro-optic modulator, wherein the silicon layer and the nonlinear optical material layer are stacked together to form the hybrid waveguide, and the conductive wiring structures located on both sides of the silicon layer are electrically connected to the conductive wiring structures located on both sides of the nonlinear optical material layer to form the electrodes.

[0031] In some embodiments, the nonlinear optical material layer includes at least one of the following: a barium titanate layer, a lithium niobate layer, a lithium tantalate layer, and an organic polymer. The silicon layer includes at least one of the following: a single-crystal silicon layer and a silicon nitride layer.

[0032] In some embodiments, the hybrid waveguide comprises a first hybrid waveguide formed by stacking a single-crystal silicon layer over a barium titanate layer. Optionally, the hybrid waveguide comprises a second hybrid waveguide formed by stacking a silicon nitride layer over a lithium niobate layer.

[0033] In some embodiments, the provision of the first component includes:

[0034] A first article is formed using a front-end process, the first article comprising the silicon layer;

[0035] The side of the first product closest to the silicon layer is thinned.

[0036] For the first article subjected to the aforementioned thinning treatment, conductive wiring structures are formed on at least two sides of the region corresponding to the silicon layer to obtain the first component.

[0037] In some embodiments, the provision of the second component includes:

[0038] Forming a nonlinear optical material layer on a wafer

[0039] A second article is obtained by removing the nonlinear optical material outside the predetermined region while retaining the nonlinear optical material layer in the predetermined region, wherein the predetermined region is the region that will overlap with the silicon layer;

[0040] A silicon oxide layer is further deposited on top of the second product to obtain the third product;

[0041] For the third article, conductive wiring structures are formed on both sides of the region corresponding to the retained nonlinear optical material layer to obtain the second component.

[0042] In some embodiments, the conductive wiring structure includes a conductive structure in a hole.

[0043] In some embodiments, the manufacturing method further includes:

[0044] For the electro-optic modulator obtained by bonding the first component and the second component together, a bonding structure for bonding with other components is formed on at least one surface of the electro-optic modulator.

[0045] According to the above embodiments, the present invention employs a front-end process to fabricate a first component, which can be a photonic integrated chip. A second component, such as a barium titanate thin film or a lithium niobate thin film, is fabricated using nonlinear optical materials such as barium titanate, lithium niobate, lithium tantalate, or organic polymers. Then, a back-end process (e.g., wafer bonding, via wiring) is used to combine the barium titanate thin film or lithium niobate thin film with the photonic integrated chip. The resulting modulator is capacitive, with extremely small capacitance, making it very easy to drive, exhibiting no static power consumption and extremely low dynamic power consumption. Therefore, the present invention can integrate small-size, high-efficiency, low-power electro-optic modulator technologies—which are incompatible with traditional CMOS (Complementary Metal-Oxide-Semiconductor)—into classic silicon-based optoelectronic processes.

[0046] Various aspects, features, advantages, etc., of the embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings. These aspects, features, advantages, etc., will become clearer from the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of an electro-optic modulator according to an embodiment of the present invention.

[0048] Figure 2 This is a schematic diagram of an electro-optic modulator according to another embodiment of the present invention.

[0049] Figure 3a This is a top view showing an example of the gradient structure of the coupling end of the electro-optic modulator according to an embodiment of the present invention.

[0050] Figure 3b yes Figure 3a A cross-sectional view of the structure shown.

[0051] Figure 3c yes Figure 3a BB cross-sectional view of the structure shown.

[0052] Figure 4a This is a top view showing another example of the gradient structure of the coupling end of the electro-optic modulator according to an embodiment of the present invention.

[0053] Figure 4b yes Figure 4a The aa section view of the structure shown.

[0054] Figure 4c yes Figure 4a The bb cross-sectional view of the structure shown.

[0055] Figure 4d yes Figure 4a The cc section view of the structure shown.

[0056] Figure 5a This is a top view showing an example of a hybrid waveguide of an electro-optic modulator according to an embodiment of the present invention.

[0057] Figure 5b yes Figure 5a The image shows a longitudinal cross-section of the hybrid waveguide.

[0058] Figure 6a This is a top view showing yet another example of a hybrid waveguide of an electro-optic modulator according to an embodiment of the present invention.

[0059] Figure 6b yes Figure 6a The image shows a longitudinal cross-section of the hybrid waveguide.

[0060] Figure 7This is a cross-sectional view of a stage of a manufacturing method for an electro-optic modulator according to an exemplary embodiment of the present invention.

[0061] Figure 8 Is Figure 7 A cross-sectional view of the product at the stage following the stage shown.

[0062] Figure 9 Is Figure 8 A cross-sectional view of the product at the stage following the stage shown.

[0063] Figure 10 This is a cross-sectional view of an article produced at another stage in a method for manufacturing an electro-optic modulator according to an exemplary embodiment of the present invention.

[0064] Figure 11 This is a cross-sectional view of an article produced at another stage in a method for manufacturing an electro-optic modulator according to an exemplary embodiment of the present invention.

[0065] Figure 12 Is Figure 11 A cross-sectional view of the product at the stage following the stage shown. Detailed Implementation

[0066] To facilitate understanding of the various aspects, features, and advantages of the technical solution of this invention, the invention will be described in detail below with reference to the accompanying drawings. It should be understood that the various embodiments described below are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0067] The term "including" as used herein is an open-ended term and should therefore be interpreted as "including but not limited to". "Approximately" means that, within an acceptable range of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0068] Furthermore, the term "connection" here includes any means of connection, both direct and indirect. Therefore, if the text describes a first device connected to a second device, it means that the first device can be directly connected to the second device, or indirectly connected to the second device through other devices.

[0069] The terms "first," "second," etc., used herein are for distinguishing different devices, modules, structures, etc., and do not represent a chronological order, nor do they limit "first" and "second" to different types. Furthermore, some processes described in the specification, claims, and accompanying drawings of this application include multiple operations, steps, or procedures appearing in a specific order. These operations, steps, or procedures may be performed out of order or in parallel. Operation numbers such as S1, S2, etc., are merely for distinguishing different operations and do not themselves represent any execution order. Additionally, these processes may include more or fewer operations, and these operations may be performed sequentially or in parallel.

[0070] In an embodiment of the present invention, the electro-optic modulator includes a hybrid waveguide and a first electrode and a second electrode disposed on both sides of the hybrid waveguide. The hybrid waveguide comprises a stacked silicon layer and a nonlinear optical material layer. Couplers for optical coupling extend from both ends of the hybrid waveguide, wherein at least one of the couplers at both ends of the hybrid waveguide has a gradient structure. One of the couplers is used to introduce an optical signal (light wave) into the hybrid waveguide, and the other is used to extract an optical signal (light wave) from the hybrid waveguide. In an optional embodiment, both couplers at both ends of the hybrid waveguide have the gradient structure. In some embodiments, the nonlinear optical material layer includes at least one of the following: barium titanate (BTO), lithium niobate, lithium tantalate, or an organic polymer layer; and / or, the silicon layer includes at least one of the following: a single-crystal silicon layer (C-Si) or a silicon nitride layer.

[0071] In some embodiments, the electro-optic modulator includes at least two of the hybrid waveguides, at least one beamsplitter, and at least one beam combiner; the output of the beamsplitter is coupled to the input side of the corresponding hybrid waveguide via a first connecting waveguide, and the input of the beam combiner is coupled to the output side of the corresponding hybrid waveguide via a second connecting waveguide.

[0072] Figure 1 One implementation of an electro-optic modulator is shown. For example... Figure 1 As shown, the electro-optic modulator includes two hybrid waveguides and three electrodes (electrode 1, electrode 2, and electrode 3). The beamsplitter is a 50 / 50 beamsplitter. The two outputs of the beamsplitter are connected to the two hybrid waveguides via a first connecting waveguide (e.g., a silicon waveguide). The outputs of the two hybrid waveguides are connected to the input of the beam combiner via a second connecting waveguide (e.g., a silicon waveguide). The beam combiner is a 1×2 beam combiner, and its output can be connected to another beamsplitter or another electro-optic modulator via a connecting waveguide (e.g., a silicon waveguide) to form a modulator network. This modulator network can form a photonic neural network for big data computation such as machine learning.

[0073] Figure 2 Another implementation of the electro-optic modulator is shown. For example... Figure 2 As shown, the structure of the electro-optic modulator in this embodiment is similar to... Figure 1 The electro-optic modulators in the illustrated embodiments are basically the same, except that the beam combiner is a 2×2 beam combiner. The two outputs of the beam combiner can be connected to another beam splitter or another electro-optic modulator to form a modulator network for photonic computation processing.

[0074] exist Figure 1 and Figure 2 In the illustrated embodiment, the two hybrid waveguides share a single electrode 2. However, the invention is not limited to this; in alternative embodiments, each hybrid waveguide may have two separate electrodes, meaning that two adjacent hybrid waveguides have two separate electrodes, each used for one of the two hybrid waveguides.

[0075] exist Figure 1 and Figure 2 In the illustrated embodiment, the two ends of the hybrid waveguide are coupled to a connecting waveguide via coupling terminals, which include a graded structure. Due to the significant mode field difference between the hybrid waveguide (e.g., a BTO-Si hybrid waveguide) and the silicon waveguide, direct connection without a graded structure would result in substantial insertion loss. In this exemplary embodiment, considering the varying thicknesses of the silicon layer in the hybrid waveguide, two examples of graded structures are proposed. These two examples of graded structures are described below.

[0076]

Gradient Structure Example 1

[0077] like Figures 3a-3c As shown, the gradient structure includes a base 901 and a deformable portion 902. The base 901 includes a nonlinear optical material layer (e.g., BTO) and a silicon layer (e.g., C-Si) stacked on top of the nonlinear optical material layer. The deformable portion 902 is connected to the base 901 and also includes a stacked nonlinear optical material layer (e.g., BTO) and a silicon layer (e.g., C-Si). The nonlinear optical material layer in the deformable portion 902 extends from the nonlinear optical material layer in the base 901 and its dimensions gradually decrease in the direction away from the base 901. The silicon layer in the deformable portion 902 extends from the silicon layer in the base 901 and its dimensions remain constant. In some embodiments, the thickness of the nonlinear optical material layer is typically around several hundred nanometers, for example, approximately 200-800 nm.

[0078] In some implementations, such as Figure 3aAs shown, the end face of the nonlinear optical material layer of the deformed section includes a slope (appearing as an inclined edge when viewed from above), and the slope has a certain angle α with the silicon layer. In some embodiments, the angle α is less than 45°, and the smaller the angle α, the lower the modulator loss. In some embodiments, in the deformed section 901, the length L of the gradient structure corresponding to the inclined surface is approximately 3 to 10 μm. If the length L is too small, it will result in a large angle α, leading to high modulator loss; if the length L is too large, the size of the coupling end will increase, which is not conducive to the miniaturization of the modulator.

[0079] Figure 3b yes Figure 3a The diagram shows a cross-sectional view (AA) of the structure. At the end of the deformed portion 902 away from the base 901, the silicon layer and the nonlinear optical material layer are far apart and have no overlapping area. Figure 3c yes Figure 3a The diagram shows a BB cross-sectional view of the structure. In the base, a silicon layer and a nonlinear optical material layer are arranged vertically, with the width of the nonlinear optical material layer being greater than the width of the silicon layer. The vertical projection of the silicon layer overlaps with that of the nonlinear optical material layer.

[0080]

Gradient Structure Example 2

[0081] like Figures 4a-4d As shown, the gradient structure includes a base 1001, a deformed portion 1002, and an intermediate portion 1003 located between the base 1001 and the deformed portion 1002. The base 1001, the deformed portion 1002, and the intermediate portion 1003 are connected. The base 1001 includes a nonlinear optical material layer (e.g., BTO) and a first silicon layer (e.g., C-Si) stacked on top of the nonlinear optical material layer. The deformed portion 1002 includes a second silicon layer (e.g., C-Si) and a nonlinear optical material layer (e.g., BTO) stacked on top of the deformed portion 1002. The intermediate portion 1003 includes a nonlinear optical material layer (BTO), a first silicon layer (C-Si) extending from the base 1001, and a second silicon layer (C-Si) extending from the deformed portion 1002.

[0082] In some embodiments, the thickness of the second silicon layer is greater than the thickness of the first silicon layer, and in the intermediate portion 1003, the second silicon layer is located above the first silicon layer. Optionally, the thickness of the first silicon layer is typically about 70 to 150 nm. In other embodiments, the thickness of the second silicon layer may be the same as or less than the thickness of the first silicon layer. In some embodiments, when viewed from above, in the intermediate portion 1003, the width of the first silicon layer extending from the base 1001 gradually increases and then gradually decreases along the extension direction, and the width of the tail portion of the second silicon layer extending from the deformed portion 1002 gradually decreases along the extension direction. In optional embodiments, the width of the first silicon layer extending from the base 1001 may remain constant along the extension direction. In optional embodiments, the width of the second silicon layer extending from the deformed portion 1002 remains constant. In other embodiments, in the intermediate portion 1003, the width of the first silicon layer extending from the base 1001 is greater than the width of the second silicon layer extending from the deformed portion 1002.

[0083] The nonlinear optical material layer included in the deformed portion 1002 extends from the nonlinear optical material layer included in the intermediate portion 1001 and its size gradually decreases in the direction away from the intermediate portion. In some embodiments, such as Figure 4a As shown, the end face of the nonlinear optical material layer of the deformed portion includes a slope (appearing as an inclined edge when viewed from above), and the slope has a certain angle β with the second silicon layer (C-Si). In some embodiments, the angle β is less than 45°, and the smaller the angle β, the lower the modulator loss. In some embodiments, in Figure 4a In the example shown, the length of part 1 (corresponding to the length of the gradient structure of the inclined surface) is approximately 3 to 10 μm, and the lengths of parts 2 and 3 are 20 to 30 μm respectively. If the lengths of parts 1, 2 and 3 are too small, the transition between the nonlinear optical material layer, the first silicon layer and the second silicon layer will be too steep, resulting in high loss of the modulator. If the lengths of parts 1, 2 and 3 are too large, the size of the coupling end will increase, which is not conducive to the miniaturization of the modulator.

[0084] According to the above embodiments, the gradient structure example 1 is applicable to the case where the thickness of the silicon layer in the hybrid waveguide is the same as the thickness of the silicon waveguide in the connecting waveguide, and the gradient structure example 2 is applicable to the case where the thickness of the silicon layer in the hybrid waveguide is further reduced.

[0085] In various embodiments of this invention, the hybrid waveguide is the main region for realizing electro-optic modulation. In conventional silicon photonic modulators, the refractive index of the material is adjusted by regulating the distribution of charge carriers through applied voltage or current signals, thereby adjusting the effective refractive index of the mode field. The hybrid waveguide, however, operates based on the nonlinear optical effects of nonlinear optical materials, adjusting the refractive index of the material (while keeping the refractive index of the silicon layer constant) by adjusting the intensity of the applied electric field. For example, in a BTO-Si hybrid waveguide, based on the nonlinear optical effects of BTO material, the refractive index of the BTO material is adjusted by adjusting the intensity of the applied electric field. Therefore, the overlap between the optical mode and the BTO layer affects the modulation efficiency. The higher the overlap, the greater the influence of the BTO material on the effective refractive index, and the higher the corresponding modulation efficiency. To adjust the overlap, the thickness of the silicon layer can be adjusted, and the width of the silicon layer can be selected according to wavelength requirements. Generally, the thinner the silicon layer in the hybrid waveguide, the more the mode field is distributed in the BTO material, resulting in higher efficiency. Figure 5a and Figure 5b Example 1 of a hybrid waveguide is shown. Figure 6a and Figure 6b Example 2 of the hybrid waveguide is shown. The main difference between the two examples is the thickness of the silicon layer (C-Si).

[0086] In some embodiments, the coupling end of Example 1 of the hybrid waveguide is adapted to adopt the gradient structure of Example 1 described above, and the coupling end of Example 2 of the hybrid waveguide is adapted to adopt the gradient structure of Example 2 described above. In optional embodiments, the gradient structure of Example 1 described above can also be used in Example 2 of the hybrid waveguide, or the gradient structure of Example 2 described above can also be used in Example 1 of the hybrid waveguide.

[0087] The method for manufacturing an electro-optic modulator is described below. This method is suitable for manufacturing electro-optic modulators according to any of the above embodiments or examples. For ease of explanation, only one hybrid waveguide is illustrated in the examples.

[0088] In one embodiment of the present invention, a method for manufacturing an electro-optic modulator comprising at least a hybrid waveguide and electrodes located on both sides of the hybrid waveguide includes:

[0089] S1. A first component is provided, the first component comprising at least a silicon layer and conductive wiring structures located on both sides of the silicon layer. In some embodiments, the conductive wiring structures are located on the outer sides of the silicon layer. In some embodiments, the conductive wiring structures are adjacent to the silicon layer or located on the inner sides of the silicon layer.

[0090] S2. A second component is provided, the second component comprising a nonlinear optical material layer and conductive wiring structures located on both sides of the nonlinear optical material layer. In some embodiments, the conductive wiring structures are adjacent to the nonlinear optical material layer or located on the inner sides of both sides of the nonlinear optical material layer. In some embodiments, the conductive wiring structures are located on the outer sides of both sides of the nonlinear optical material layer.

[0091] S3. The first component and the second component are bonded together to form the electro-optic modulator, wherein the silicon layer and the nonlinear optical material layer are stacked together to form the hybrid waveguide, and the conductive wiring structures located on both sides of the silicon layer are electrically connected to the conductive wiring structures located on both sides of the nonlinear optical material layer to form the electrodes.

[0092] In some embodiments, the first component includes a photonic integrated chip (PIC) and an interlayer dielectric (ILD). In step S1, the first component can be obtained in a commercial wafer fab using the PIC's front-end of line (FEOL) process. A silicon layer and conductive wiring structures are formed in the first component, the silicon layer including at least one of a single-crystal silicon layer (C-Si) and a silicon nitride layer. In some embodiments, the first component, in addition to the silicon layer and conductive wiring structures, also includes one or more other optical devices.

[0093] In some embodiments, independent of step S1, in step S2, a nonlinear optical material layer of a certain thickness and a conductive wiring structure are deposited on an SOI (silicon-on-insulator) wafer to obtain a second component. The nonlinear optical material layer includes at least one of the following: barium titanate (BTO), lithium niobate, lithium tantalate, or an organic polymer layer. It should be understood that step S2 is independent of step S1, and the two are not dependent on each other. Step S1 can be performed first, followed by step S2, or vice versa. In optional embodiments, steps S1 and S2 can be performed in parallel to improve production efficiency.

[0094] In some embodiments, in step S3, the first component and the second component are directly bonded together via wafer bonding in the back-end of line (BEOL) process of the PIC to obtain the electro-optic modulator. Furthermore, the silicon layer and the nonlinear optical material layer are stacked together to form the hybrid waveguide. In some embodiments, a single-crystal silicon layer (C-Si) is stacked on top of a barium titanate (BTO) layer to form the hybrid waveguide. Optionally, a silicon nitride layer may be stacked on top of a lithium niobate layer to form the hybrid waveguide.

[0095] The electro-optic modulator fabricated using the above process is capacitive, with extremely small capacitance, making it very easy to drive. It has no static power consumption and extremely low dynamic power consumption. Compared to existing modulators, the electro-optic modulator has lower energy consumption and smaller size.

[0096] In an exemplary embodiment, step S1, providing the first component includes the following steps:

[0097] 1: The first product is formed using a front-end manufacturing process, such as... Figure 7 As shown, the first product can be a finished or semi-finished product of a stacked chip, comprising a single-crystal silicon layer 101. Optionally, the front-end process can be completed in a commercial wafer fab to obtain the stacked chip. In some embodiments, the first product may also include a germanium-silicon photodetector (Ge-Si PD) 102, a modulator or VOA (optical attenuator) based on carrier dispersion effect 103, and other passive devices, etc. The first product is fabricated using an SOI substrate, with the single-crystal silicon layer 101 disposed in the top silicon layer of the SOI, separated from the bottom silicon layer by a buried silicon oxide layer, and covered by a dielectric layer, which can be made of silicon oxide.

[0098] 2: The first article is subjected to a thinning process. In some embodiments, such as... Figure 8 As shown, a new substrate 106 is bonded to the upper surface of the first product, and then the original substrate 105 is removed, and part of the silicon oxide 104 below the first product is removed to thin the silicon oxide below the single crystal silicon layer 101 to a thickness of 0-50 nm. If the silicon oxide layer below the single crystal silicon layer 101 is greater than 50 nm, the distance between the single crystal silicon layer 101 and the subsequently formed nonlinear material layer is too far, and the distance between the two formed by the hybrid waveguide is too far, resulting in poor modulation effect.

[0099] 3: For the first article subjected to the aforementioned thinning treatment, conductive wiring structures serving as electrodes are formed at least on both sides of the region corresponding to the single-crystal silicon layer 101. These conductive wiring structures include a first conductive wiring structure 107 and a second conductive wiring structure 108, resulting in a first component 100, such as... Figure 9 As shown. Specifically, as Figure 9As shown, the first product after process 2 is flipped 180° so that the new substrate 106 faces downwards. Then, windows are opened at the desired locations, for example, on both sides of the single-crystal silicon layer 101, corresponding to the regions of the nonlinear optical material layer to be bonded, and metal is deposited to form a first conductive wiring structure 107 and a second conductive wiring structure 108. The surfaces are then chemically and mechanically polished. In this embodiment, the first conductive wiring structure 107 and the second conductive wiring structure 108 are conductive structures that pass through a substrate via (TSV). In optional embodiments, the first conductive wiring structure 107 and the second conductive wiring structure 108 can employ other structures suitable in the art, such as metal conductive traces or buried wires.

[0100] The first component 100 is obtained through the above three processes. In this embodiment, the first component 100 can be a photonic integrated chip, which includes a single-crystal silicon layer 101 and other optical devices. For example, the other optical devices include a germanium-silicon photodetector (Ge-Si PD) 102, a modulator or VOA (optical attenuator) 103 based on carrier dispersion effect, and a connecting waveguide (e.g., a silicon waveguide).

[0101] In an exemplary embodiment, step S2, providing the second component includes the following steps:

[0102] (i) Forming a nonlinear optical material layer, such as a barium titanate (BTO) layer, on a wafer. In some embodiments, a nonlinear optical material layer of a certain thickness is obtained on an SOI wafer by techniques such as epitaxial growth or chemical solution deposition.

[0103] (ii): Removing the nonlinear optical material layer outside the predetermined region while retaining the nonlinear optical material layer in the predetermined region yields a second product, wherein the predetermined region is the region to be overlapped with the single-crystal silicon layer 101. Specifically, the nonlinear optical material layer that does not need to be retained can be removed by dry etching.

[0104] (iii): A silicon oxide layer is further deposited on top of the second product to smooth the surface of the nonlinear optical material layer, so as to obtain the third product;

[0105] (iv): For the third article, conductive wiring structures are formed on both sides of the region corresponding to the retained nonlinear optical material layer to obtain the second component. Specifically, the conductive wiring structure is formed by opening holes and depositing metal or performing a TSV back-end process at the required locations. The conductive wiring structure can be a conductive structure that penetrates through a substrate via. Optionally, the upper surface of the second component is polished and thinned as much as possible. Specifically, the silicon oxide above the nonlinear optical material layer is thinned as much as possible to reduce the gap between the nonlinear optical material layer and the single-crystal silicon layer. Optionally, the thickness of the nonlinear optical material layer is generally around several hundred nanometers.

[0106] like Figure 10 As shown, the second component 200 obtained through the above four processes includes a nonlinear optical material layer 201, a third conductive wiring structure 207, and a fourth conductive wiring structure 208. In this embodiment, the third conductive wiring structure 207 and the fourth conductive wiring structure 208 are conductive structures that penetrate through vias in the substrate. The invention is not limited thereto; in optional embodiments, the third conductive wiring structure 207 and the fourth conductive wiring structure 208 can employ other suitable structures in the art, such as metal conductive traces or embedded wires.

[0107] In an exemplary embodiment, in step S3, during the back-end process of the PIC, the first component 100 and the second component 200 are directly bonded together using a wafer bonding process to obtain an electro-optic modulator. In some embodiments, such as Figure 11 As shown, a second component 200 is bonded to the upper surface of a first component 100, and a new substrate 106 is removed. A nonlinear optical material layer 201 is located above a single-crystal silicon layer 101 to form a hybrid waveguide. A first conductive wiring structure 107 is electrically connected to a third conductive wiring structure 207 to form a first electrode, and a second conductive wiring structure 108 is electrically connected to a fourth conductive wiring structure 208 to form a second electrode, thereby obtaining the electro-optic modulator. In the electro-optic modulator, the first and second electrodes are used to apply an electric field to the hybrid waveguide, which changes the refractive index of the hybrid waveguide, thereby modulating the optical signal passing through the hybrid waveguide. In some embodiments, when the electrical signal applied by the first and second electrodes carries data or information, the modulation carries the data or information into the optical signal. In some embodiments, the electro-optic modulator is used to construct a photonic neural network, whereby the modulation allows the information carried by the optical signal to be processed using the weight information carried by the electrical signal, for example, through convolution operations.

[0108] In some implementations, such as Figure 12As shown, for a product (i.e., an electro-optic modulator) obtained by bonding the first component and the second component together, a bonding structure 300 for bonding with other components is formed on at least one surface of the product. The bonding structure 300 may be a solder ball, a microbump, etc. In some embodiments, the microbumps on the upper surface of the electro-optic modulator are primarily used for interconnection with an electrical integrated circuit (EIC), and the microbumps on the lower surface are used for connection with the packaged substrate.

[0109] Those skilled in the art should understand that although the above embodiments mainly use BTO as an example of nonlinear optical material to illustrate the present invention, the present invention is not limited thereto. Nonlinear optical materials can also be lithium niobate, lithium tantalate, organic polymers, etc.

[0110] Those skilled in the art should understand that the above-disclosed embodiments are merely implementations of the present invention and should not be construed as limiting the scope of the patent protection claimed in this application. Equivalent variations made according to the embodiments of the present invention are still within the scope of the claims of this application.

Claims

1. An electro-optic modulator, characterized by The application relates to a hybrid waveguide and a manufacturing method thereof. The hybrid waveguide comprises a laminated silicon layer and a nonlinear optical material layer, wherein the silicon layer and the etched nonlinear optical material layer are laminated without contact to form the hybrid waveguide; and An electrode comprises a first electrode and a second electrode arranged on both sides of the hybrid waveguide; Both ends of the hybrid waveguide extend out of the coupling end for optical coupling, At least one of the coupling ends of both ends of the hybrid waveguide comprises a gradient structure; The gradient structure comprises a deformation part comprising a laminated silicon layer and a nonlinear optical material layer, and the end face of the nonlinear optical material layer of the deformation part comprises an inclined face.

2. The electro-optic modulator of claim 1, wherein, The nonlinear optical material layer comprises at least one of the following: a barium titanate layer, a lithium niobate layer, a lithium tantalate layer and an organic polymer layer; And / or, the silicon layer comprises at least one of the following: a single crystal silicon layer and a silicon nitride layer.

3. The electro-optic modulator of claim 1, wherein, In the hybrid waveguide, the vertical projection of the silicon layer is located in the vertical projection range of the nonlinear optical material layer.

4. The electro-optic modulator of claim 1, wherein, The gradient structure further comprises a base part connected with the hybrid waveguide and comprising a laminated silicon layer and a nonlinear optical material layer; The deformation part is connected with the base part, wherein the nonlinear optical material layer contained in the deformation part extends from the nonlinear optical material layer contained in the base part and gradually decreases in size in the direction away from the base part, and the silicon layer contained in the deformation part extends from the silicon layer contained in the base part and keeps constant in size.

5. The electro-optic modulator of claim 1, wherein, The gradient structure further comprises: A base part connected with the hybrid waveguide and comprising a laminated silicon layer and a nonlinear optical material layer; An intermediate part connected with the base part and comprising a laminated silicon layer and a nonlinear optical material layer; The deformation part is connected with the intermediate part, In the intermediate part, the silicon layer comprises the silicon layer extended from the deformation part and the silicon layer extended from the base part, and the silicon layer extended from the deformation part is located above the silicon layer extended from the base part, The nonlinear optical material layer contained in the deformation part extends from the nonlinear optical material layer contained in the intermediate part and gradually decreases in size in the direction away from the intermediate part.

6. The electro-optic modulator of claim 1, wherein, The inclined face of the nonlinear optical material layer contained in the deformation part has an included angle with the silicon layer contained in the deformation part when viewed from the top.

7. The electro-optic modulator of claim 6, wherein, The angle of the included angle is less than 45 degrees.

8. The electro-optic modulator of claim 5, wherein, In the intermediate part, the thickness of the silicon layer extended from the deformation part is greater than the thickness of the silicon layer extended from the base part.

9. The electro-optic modulator of claim 5, wherein, When viewed from the top, in the intermediate part, the width of the silicon layer extended from the base part gradually increases and then gradually decreases along the extension direction.

10. The electro-optic modulator of claim 5, wherein, When viewed from the top, in the intermediate part, the width of the tail of the silicon layer extended from the deformation part gradually decreases along the extension direction.

11. The electro-optic modulator of claim 1, wherein, The manufacturing method comprises: ​ ​ ​ 12. A manufacturing method of an electro-optical modulator, the manufacturing method being adapted to manufacture the electro-optical modulator according to any one of claims 1 to 11, characterized in that, ​ providing a first component comprising at least a silicon layer and electrically conductive wiring structures on both sides of the silicon layer; providing a second component comprising a layer of nonlinear optical material and electrically conductive wiring structures on both sides of the layer of nonlinear optical material; bonding the first component and the second component together to form the electro-optical modulator, wherein the silicon layer and the layer of nonlinear optical material are laminated together to form a hybrid waveguide, and the electrically conductive wiring structures on both sides of the silicon layer are electrically connected to the electrically conductive wiring structures on both sides of the layer of nonlinear optical material to form electrodes on both sides of the hybrid waveguide.

13. The manufacturing method according to claim 12, wherein The hybrid waveguide comprises a first hybrid waveguide formed by laminating a monocrystalline silicon layer on top of a barium titanate layer.

14. The manufacturing method according to claim 12, wherein The hybrid waveguide comprises a second hybrid waveguide formed by laminating a silicon nitride layer on top of a lithium niobate layer.

15. The manufacturing method according to claim 12, wherein The providing of the first component comprises: forming a first article using a front-end-of-line process, the first article comprising the silicon layer; performing a thinning process on a side of the first article close to the silicon layer; for the first article after the thinning process, forming electrically conductive wiring structures on both sides of a region corresponding to the silicon layer to obtain the first component.

16. The manufacturing method according to claim 12, wherein The providing of the second component comprises: forming a layer of nonlinear optical material on a wafer, removing the layer of nonlinear optical material except for a predetermined region to retain the layer of nonlinear optical material in the predetermined region to obtain a second article, wherein the predetermined region is a region that will overlap with the silicon layer; further depositing a layer of silicon oxide on top of the second article to obtain a third article; for the third article, forming electrically conductive wiring structures on both sides of a region corresponding to the retained layer of nonlinear optical material to obtain the second component.

17. The manufacturing method of claim 12, wherein, The electrically conductive wiring structures comprise electrically conductive structures through vias in the substrate.

18. The manufacturing method of claim 12, wherein, Further comprising: for the electro-optical modulator obtained by bonding the first component and the second component together, forming a bonding structure on at least one surface of the electro-optical modulator for bonding with a further component.

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